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全部话题 - 话题: attenuator
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t****l
发帖数: 236
1
发信人: minstrol (中世纪的吟游歌手), 信区: USTCDevelopment
标 题: 祝贺科大生物系发表一篇PNAS
发信站: 瀚海星云 (2005年11月18日23:05:18 星期五), 站内信件 WWWPOST
免疫学方面的论文,科大是唯一的作者单位。
2003年,PNAS的影响因子是10.272,属于一区论文。
Toll-like receptor 3 ligand attenuates LPS-induced liver injury by
down-regulation of toll-like receptor 4 expression on macrophages
Wei Jiang *, Rui Sun *, Haiming Wei *, and Zhigang Tian *
*Hefei National Laboratory for Physical Sciences at Microscale and School of
Life Sciences, University of Science and Technology of China,
q**w
发帖数: 782
2
http://www.technologyreview.com/view/509106/best-of-2012-chines
Best of 2012: Chinese Physicists Smash Distance Record For Teleportation
The ability to teleport photons through 100 kilometres of free space opens
the way for satellite-based quantum communications, say researchers
Teleportation is the extraordinary ability to transfer objects from one
location to another without travelling through the intervening space.
The idea is not that the physical object is teleported but the information
th... 阅读全帖
P*********r
发帖数: 242
3
欢迎访问本人微博:http://www.weibo.com/u/2488313871
http://blog.sina.com.cn/s/blog_9450a80f0101fdyx.html
政府的公权力能有多逆天(续)?“拨乱反正”的美利坚合纵国控诉洛佩兹(United
States v. Lopez)
The powers delegated by the proposed Constitution to the federal government
are few and defined. Those which are to remain in the State governments are
numerous and indefinite.
--James Madison
宪法中赋予联邦政府的权力是有限的和严格定义的;而保留给州政府的权力则很多,甚
至是无限的。
--詹姆斯。麦迪逊
在我发表了第一篇Wickard v. Filburn之后我也看到了很多网友的回复,我比较重视别
人对我的不同看法,我看有网友质疑我拿一个美国1940的法律案例和今天的中国相比有
何意义。这是个很... 阅读全帖
A***l
发帖数: 302
4
来自主题: XMU版 - WHY SYNTHETIC PEPTIDE VACCINE?
Since Edward Jenner developed the first vaccine to prevent smallpox
infections, vaccination has gradually become one of the most effective
medical interventions against many bacterial and viral diseases.
Traditionally the vaccines were live strains derived from virulent
cultures isolated from cases of natural infection. For example, attenuated
vaccines, killed vaccines and toxoid vaccines (detoxified toxins) have
been successfully applied to a variety of diseases including cholera,
plague, dysen
m*****a
发帖数: 999
5
在其他方面,比如文学、美术、音乐、哲学、军事理论等等,中国古代都有登峰造极的
一面,但为什么唯独科学家很少很少。
有人认为这是东西方文化的差异,我觉得根本不是,差异是说同一种东西,在东方发展
成这样、在西方发展成那样,比如说东方有东方的文学艺术,西方有西方的文学艺术,
虽然不同,但都是文学艺术。但是西方后来慢慢发展出了物理化学生物医学等等学科,
中国的这些学科在哪里。
就我的认知水平,我觉得古代那些技术、发明,基本都是engineering层面,没上升到
science层面。指南针很早就发明了,但是好像没有继续深入研究地球的磁场什么的,
没有延伸到电磁学。造纸术很早就有了,怎么没有继续深入到植物内部的构造、植物学
、动物学、生物学等等。火药很早就有了,怎么没有深入去研究化学。
然后就是很可气的中医,一两千年之前是望闻问切,现在还是望闻问切,什么工具都没
发明。以前凭经验吃草药可以治点小毛病,现在在癌症之类的大病面前中医还是束手无
策。西医从最初的解剖学能看到人体器官开始,现在已经dive down到molecular level
了。比如说西医按照自己的理论不断研究下去,发现了stem... 阅读全帖
m*****a
发帖数: 999
6
儒家文化遵从古法,也不能说完全不好,只是不能完全遵从、生搬硬套。反正对于古法
,应该是取其精华弃其糟粕。我觉得就是不能非黑即白,不能全部遵从,也不能全部放
弃。
健康/非健康、良性肿瘤/恶性肿瘤,都有定义啊。肿瘤的原因是DNA mutation,
mutation的原因是外界刺激,这些都是现在已经研究出来的成果,至于什么样的外界刺
激会导致什么样的肿瘤,那都在研究的过程当中。我觉得总有一天会有结果的。要不然
,也不会现在有些癌症已经有疫苗了,比如cervical cancer
你的说道玄学的特点我都认真读了,我觉得就是这样,太玄乎了,不容易被大家理解,
所以传承下来很难。如果你自己就没有理解透彻,然后你教给我,肯定不能教给我全部
的内容,这样一代一代传下去,每代都有attenuation,那传到现在早就面目全非了。
。。我觉得这就可以解释,为什么西医发展很迅速,中医相对停滞不前。
m*****n
发帖数: 3575
7
"你的说道玄学的特点我都认真读了,我觉得就是这样,太玄乎了,不容易被大家理解,
所以传承下来很难。如果你自己就没有理解透彻,然后你教给我,肯定不能教给我全部
的内容,这样一代一代传下去,每代都有attenuation,那传到现在早就面目全非了。"
很对. 其实中医学术的发展很像原地打转.
到了清末的著名名医张锡纯,还在重复神农本草的实验.
a***y
发帖数: 19743
8
来自主题: Apple版 - Apple fires back at Nokia
Apple admits the spot is iPhone 4's weak spot, which Apple highlighted with
circle in the press conference.
I personally think it is a design flaw because of its placement.
However Apple should point out every phone has its own weak spot, which some
companies are shamefully denying. It is unfortunate Apple has to do this,
since it is getting some unfair attention which make iPhone 4 the seemingly
only phone that suffer from signal attenuation.
In a way, the media's focus on this issue forced Ap
g****n
发帖数: 3370
9
来自主题: Hardware版 - DSL上网超级疑难请求建议
这个问题已经让我纠结了两个月了,实在无计可施了。请教一下各位看看有什么建议没
有。
先谢过了!
我用的DSL上网,dry-loop, modem工作在bridge状态,router负责PPPoE及其他。
用了几年好好的,但从两个月前开始,出现断线情况。症状是,突然没有征兆
的PPPoE断开,但modem的DSL灯还亮着,看它的状态依然是sync的,看log也看不出
有什么不正常。但看router的log,断线时出现这样的信息:
LCP appears to be disconnected
Sending PADI
Resending...
All WAN down. Reconnecting ...
也就是说router发出PADI但接收不到PADO。这种情况多发生在正在BT下载时,比如
今天,已经连线2天多了,我从5点开始下载,结果在10点发生状况。
解决的办法只有一条:重启modem。重启后马上连上。
已经换掉router和modem,新的问题依然存在。所以基本可以排除router/modem问题。
关于线路,在发生问题前后线路没动过,而且modem状态显示SNR margin和衰... 阅读全帖
n******h
发帖数: 2544
10
来自主题: Hardware版 - 求教电脑风扇减速线
This may not work. Since the motherboard will check the fan status. Once I
unplug the fan's power, it won't start.
Is there any attenuator can work in this case?
m**o
发帖数: 13
11
来自主题: Biology版 - Re: Help: exposed to P32
P32 has a little bit high emission of beta particles. Beta particles are
completely attenuated by small thicknesses of common materials.Therefore, they
do not pose an external source of radiation dose. Even a high energy beta
particle from a P-32 decay event can only penetrate about 8 millimeters of
tissue. Our radiation-sensitive organs are typically at least 12 to 25
millimeters below the skin surface. However, a beta emitter can cause
radiation dose if ingested. So don't worry too much.
And u
i***a
发帖数: 105
12
3.13日听了卢山教授(U of Mass. Medical School)关于基因免疫的讲座,将内容在
此整理一下。
据说这个方面的研究他处于领先水平。
一 传统的免疫包括:
1.live attenuated vaccines 即靠减活来获得免疫,安全性差
2.innactivated vaccines 灭活,免疫效果差
3.subunit vaccines, 即用病毒的亚结构做。但是,现在为止只有乙肝方面获得了
成功
。因为找到合适的亚结构其实很难
4.polysaccharide and conjugated vaccines 大意是使用糖做标记
二 recent progress(进入分子生物时代,自然出现了gene-based method)
1. DNA vaccine,直接用naked DNA打入人体作为vaccine
2. Vector mediated 主要是virus vectors
3. prime+boost 大概就是组合的方法,包括 DNA+viral Vector和DNA+protein的方
法。
其中后者是卢教授工作的重心。
k********l
发帖数: 7
13
来自主题: Biology版 - paper help--Lung Cancer
文章名 :
Human umbilical cord matrix-derived stem cells expressing interferon-beta
gene significantly attenuate bronchioloalveolar carcinoma xenografts in SCID
mice.
期刊名 :
Lung Cancer. 2010 Feb 4
全文链接 :
http://linkinghub.elsevier.com/retrieve/pii/S0169-5002(10)00005-X
http://www.lungcancerjournal.info/article/S0169-5002(10)00005-X/fulltext
h*******[email protected]
b******n
发帖数: 82
14
来自主题: Biology版 - 晓东的Cell文章
http://www.cell.com/abstract/S0092-8674%2810%2901180-3
The ER UDPase ENTPD5 Promotes Protein N-Glycosylation, the Warburg Effect,
and Proliferation in the PTEN Pathway
Min Fang, Zhirong Shen, Song Huang, Liping Zhao, She Chen, Tak W. Mak,
Xiaodong Wang
* Highlights
* The ER UDPase ENTPD5 is upregulated by AKT in PTEN mutant cells
* ENTPD5 hydrolyzes UDP to UMP to promote protein N-glycosylation
* ENTPD5, along with CMPK1 and AK-1, hydrolyze ATP to AMP, increasing
aerobic glycolys... 阅读全帖
o**d
发帖数: 3080
15
pubmed: Gong Zhang, Zoya Ignatova
1.Polyglutamine expansion alters the dynamics and molecular architecture of
aggregates in dentatorubropallidoluysian atrophy.
Hinz J, Lehnhardt L, Zakrzewski S, Zhang G, Ignatova Z.
J Biol Chem. 2012 Jan 13;287(3):2068-78. Epub 2011 Dec 1.
PMID:
22134925
[PubMed - in process]
2.Length-dependent translation of messenger RNA by ribosomes.
Valleriani A, Zhang G, Nagar A, Ignatova Z, Lipowsky R.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Apr;83(4 Pt 1):04... 阅读全帖
l**********1
发帖数: 5204
16
Johns Hopkins too 连tenure都过不了
不是看已有领域的挖掘 还要看新领域的digged out data and results.
please refer:
for example:
Lee Martin, Ph.D.
Professor of Pathology, Neuroscience
//pathology.jhu.edu/department/divisions/neuropathology/faculty-staff.cfm
his group recent paper:
线粒体上的控制 NO 的通道控制着细胞老化和自然死亡的过程
"The mitochondrial permeability transition pore regulates nitric oxide-
mediated apoptosis of neurons induced by target deprivation.” (2011)
J Neurosci. 31: 359-370.
PubMed link:
//www.ncbi.nlm.nih.gov/pubmed/2... 阅读全帖
p********e
发帖数: 609
17
来自主题: Biology版 - 做Autophagy的请进
Went through it quickly so don't quote on my comments.
The title is certainly overstated. There are many cavities in this work, to
name a few:
1) CCI -> mTOR inhibition >> autophagy: may or may not related with
autophagy.
2) CCI suppresses necrosis?: not well-defined.
3) Is downregulation of RIP3 a cause or consequence of attenuated cell death
? Not answered.
4) How does CCI regulate the RIP1/RIP3 levels?
... Plus, the quality of the data is not that great.
Just my 2 cents.
m**********3
发帖数: 706
18
今天查文献,关键词搜索" survival,retinal neurons". 有一篇文章让我很迷惑。仔
细一看名字和地址,莫非是气功大师的杰作。求鉴定。如果真是,那严大师应该是所有
这些大师,教主里头科研素质最高的了。放在国内都可以PHD毕业了。甚至秒杀大部分
博导.
Int J Neurosci. 2002 Oct;112(10):1209-27.
XY99-5038 promotes long-term survival of cultured retinal neurons.
Yan X, Fong YT, Wolf D, Shen H, Zaharia M, Wang J, Wolf G, Li F, Lee GD, Cao
W.
Source
Institute of Chongqing Traditional Chinese Medicine, Chongqing, Sichuang, P.
R. of China.
Abstract
We have previously reported that XY99-5038, a preparation from a spec... 阅读全帖
L*********y
发帖数: 322
19
来自主题: Biology版 - 投什么杂志?

You might want to do more function-structural analysis of this transporter
to back up your data.
For example, within this transporter, can you identify the key amino acid
residues or protein domains that affect the compound binding? Second,
can you synthesize a fluorophore or radiation conjugated version of this
new compound you discovered? If yes, you should be able to test its
interaction with your transporter by IP.
Third, Can you do some in vivo experiments to support you in vitro findings... 阅读全帖
q******g
发帖数: 3858
20
来自主题: Biology版 - 投什么杂志?
For example, within this transporter, can you identify the key amino acid
residues or protein domains that affect the compound binding?
We will examine the amino acid uptake in oocytes expressing mutant with
compound.
Second, can you synthesize a fluorophore or radiation conjugated version of
this new compound you discovered? If yes, you should be able to test its
interaction with your transporter by IP.
This is a revesible inhibitor for transporter. I am afraid that compound
will not bind to t... 阅读全帖
C**S
发帖数: 522
21
“--- the paper appeared online in the International Journal of
Biochemistry & Cell Biology. The print version followed in September ---”
“--- two first authors share the honor ---”.
“---four authors had been added, and two dropped---”;
根据上面的几个依据,
1: 印刷版在9月出来。根据该杂志出版的速度,9月印刷的是9月刊或10月刊,10月刊
全都是review,只能是9月刊。
2: 两个并列一作。既然是买的,两个人的应该不在一个单位。
3:加了四个作者。至少6个作者吧。
基本判断是这篇文章了:
http://www.sciencedirect.com/science/article/pii/S1357272513002
Survivin up-regulates the expression of breast cancer resistance ... 阅读全帖
b******j
发帖数: 361
22
【 以下文字转载自 Immigration 讨论区 】
发信人: baggiosj (baggio), 信区: Immigration
标 题: 请帮忙下载几篇文章, 在线等
发信站: BBS 未名空间站 (Tue Jan 7 23:13:07 2014, 美东)
1. FGF, TGFβ and Wnt crosstalk: embryonic to in vitro cartilage development
from mesenchymal stem cells, journal of tissue engineering and regenerative
medicine.
DOI: 10.1002/term.1744
2. Enhancing human nucleus pulposus cells for biological treatment
approaches of degenerative intervertebral disc diseases: a systematic review
,journal of tissue engineering and r... 阅读全帖
y****i
发帖数: 455
23
Nat Rev Nephrol. 2014 Feb 18. doi: 10.1038/nrneph.2014.21. [Epub ahead of
print]
Genetics: Epigenetic reversal attenuates renal fibrosis.
Holmes D.
PMID: 24535424 [PubMed - as supplied by publisher]
email: y****[email protected]
r*******e
发帖数: 123
24
来自主题: Biology版 - 文章求助
Magnes Res. 2014 Feb 1;27(1):16-24. doi: 10.1684/mrh.2014.0358.
Magnesium nitrate attenuates blood pressure rise in SHR rats.
PMID: 24827813
请发给我的e-mail:
s*********[email protected]
谢谢!
b**********s
发帖数: 460
25
来自主题: Biology版 - 肘子还没发表评论?
Apicoplast是疟原虫所特有的,对其生存是必须的。这个研究是通过the apicoplast-
minus strains,使疟原虫毒性大大减弱,并可能激发人体免疫系统反应,从而为开发
首个抗疟疾疫苗提供了依据。“the apicoplast-minus strains dependent on IPP
for continued growth are a unique and ideal candidate for an attenuated
blood-stage vaccine”。
明白没有,领域中人?疫苗的药物靶点还真的不一定是抗原本身,不是吗?至于
Apicoplast能不能成为疫苗的直接靶点,相信感兴趣的人肯定有。当然抗疟疾疫苗的靶
点还有其它的,也会发现更多。这中现象很难理解吗?
s******a
发帖数: 134
26
来自主题: Biology版 - Postdoc Position in Immunology
The Avram Laboratory at University of Florida is seeking a postdoc or a
visiting Ph.D. student researcher. Our laboratory focuses on transcriptional
control of effector lymphocytes in autoimmunity. Our recent work has been
published in many high-impact journals, such as Immunity, J Clin Invest, and
J Exp Med. We are seeking candidates who are self-motivated and career-
oriented to join an exciting highly interactive research team. Interested
candidates are encouraged to contact Dr. Avram by e-m... 阅读全帖

发帖数: 1
27
来自主题: Biology版 - 北京理工QING HONG的文章探讨
最近查询文章,发现跟帕金森病相关的LRRK2研究一个有趣现象,其中有一篇是现任北
理工的庆宏教授发表的LRRK2能够直接结合a-Synuclein并且磷酸化Serine-129位点。
但是后续大量的综述讨论的时候提到他这篇文章时说this is the only one paper
show LRRK2 can phosphorylate S129-synuclein。我看他发表的这篇BBRC已经被引用
快超100次了,如果文章的结论有问题,那岂不是严重阻碍了关于LRRK2-G2019S的研究
?大伙有兴趣的可以来共同探讨,或者找庆教授讨论。电子邮件:[email protected]/* */
个人简历
教育背景:
1993.9-1996.7:博士,广州中山医科大学,神经生物学
工作经历:
2006.2- 至今:北京理工大学生命科学与技术学院,教授
2001.9 – 2006.2:英属哥伦比亚大学精神病学系,脑研究中心,研究员
2000.7 – 2001.8:加拿大萨斯喀彻温大学,神经精神病学系,博士后
1997.7- 2000.6:美国埃默里大学医学院,放射肿瘤系与细胞... 阅读全帖
d**p
发帖数: 149
28
The idea is not original.
When I was interviewed with a New York start up Codagenix , I read several
their publications.
http://www.codagenix.com/technology/
The first important publication is on Science on 2008:
Coleman JR, Papamichail D, Skiena S, Futcher B, Wimmer E, Mueller S. Virus
attenuation by genome-scale changes in codon pair bias. Science 2008. 320(
5884):1784-1787. PMID: 18583614
p*******o
发帖数: 166
29
来自主题: ChemEng版 - paper help plz
Andrew A. Kline, Michael E. Mullins, Bahne C. Cornilsen (1991)
Sol-Gel Kinetics Followed by Cylindrical Attenuated Total Reflectance Infrar
ed Spectroscopy
Journal of the American Ceramic Society 74 (10), 2559–2563.
Link: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1151-2916.1991.tb06
799.x?cookieSet=1&journalCode=jace
Email: p*******[email protected]
Thank you very much!
A******y
发帖数: 2041
30
Tell me about it...I have nightmare about publishing...found a novel
selective inhibitor and only inhibits one out of 11 isoenzymes (I did IC50s
on all of 11 isozyes on all compounds), the reviewers still think it is not
specific because its IC50 is at ~1 microM. I even over-expressed the
proposed target and shown the over-expression attenuates the toxicity of the
compound...still under review :( over a month.
d********y
发帖数: 176
31
好像以前也在这里也回答过你的光谱学问题。
透射光 should refer to the forward-traveling laser excitation. so it is not
Rayleigh scattering.
if you only worry about 透射光, then a 90 degree or a back scattering (which
most modern commercial instruments use) doesn't have this problem because
by definition 透射光 doesn't go to the detector.
but if you worry about Rayleigh, regardless what geometry is used (back
scattering, forward scattering, 90
degree), the Rayleigh scattering is usually many many times stronger than
the Raman ... 阅读全帖
d**********t
发帖数: 82
32
楼上正解

not
which
attenuates
y****i
发帖数: 1504
33
借帖子请教一个问题,diamond在1900-2400的红外吸收是什么原理?无论什么光学支,
不应该有任何偶极矩的变化啊?

not
which
attenuates
f*****n
发帖数: 1324
34
来自主题: Chemistry版 - 文献求助,包子答谢
https://www.osapublishing.org/viewmedia.cfm?uri=LACSEA-2012-LT6B.1&seq=0
S. Pengel, B. Schönberger, S. Nayak, and A. Erbe, "Attenuated Total
Reflection Mid-IR-spectroscopy for Electrochemical Applications using a QCL,
" in Lasers, Sources, and Related Photonic Devices, OSA Technical Digest (CD
) (Optical Society of America, 2012), paper LT6B.1.
l*****r
发帖数: 990
35
来自主题: CivilEngineering版 - [原创] 对于Ground Motion的一些简介
相应号召,来个原创
本次地震由龙门山逆冲断层引起的, 此断层长350公里, 走向(strike)由西南-东北,断
层向西北方向倾斜(dip angle). 震中(epicenter)由北川开始, 断层向东北方向开裂.
逆冲断层由于能量释放不完全,会余震不断,继续释放能量,直到达到新的平衡。从美
国地震局的资料看,几千次余震,都发生在此断层线上.
虽然地震无法预测,但地震发生大小及可能性是可以用概率方法确定的。结构的抗震设
计要求,就是根据在某断层发生某级地震,可能引起地表多大的加速度来确定的。这种
确定,往往要对断层模型进行大量的研究,并且制定成设计规范。
在假定某断层发生某级地震的前提下,确定地表运动的预测模型 (ground motion
attenuation relations)非常重要。当前科技下,这种模型大多是基于地震记录的统计
模型。某个建筑,在某次地震下所受到的加速度,是与断层的类型, 震级, 距离, 和当
地的场地情况有关的。一般来说,震级越大,距离越近,加速度越大。场地的作用也非
常明显:岩石地基上的地震波,含有大量的高频波;而传到土基上的地震波,含有大量
的低频震
s***n
发帖数: 821
36
来自主题: CivilEngineering版 - [原创] 对于Ground Motion的一些简介
“地表运动的预测模型 (ground motion attenuation relations)”
最好不要使用 “预测模型”这个字眼。。。主要因为这根本不是预测。翻译成衰减模
型比较好一些。
统计学的方法我也做过一些。在加州比较有用。本质上是一种经验式的方法。不太能够
揭示问题的物理和力学本质。

裂.
f**u
发帖数: 559
37
The point is how do you calculate the snr? because it is tricky. it is signal
and noise.
uaually ppl forcus on the int1 noise which comes from two sides: switch noise
and opamp noise.
switch noise is kt/c, so big cap helps.
opamp noise you can run hspice and later refer all them back to your input
side.
also noise and distortion are two different issues. good settling help
distortion. big dc gain at int1 help its distortion, also help to attenuate
int2, int3 etc noise and distortion (that is the
s******e
发帖数: 2181
38
来自主题: EE版 - ultra low frequency amplifier
Thank you upstairs!
Can I increase the input capacitor to 22 uF so that the impedience for low
frequency attenuates? The original input capacitor was 1 uF.
s******e
发帖数: 2181
39
来自主题: EE版 - ultra low frequency amplifier
Thank you upstairs!
Can I increase the input capacitor to 22 uF so that the impedience for low
frequency attenuates? The original input capacitor was 1 uF.
s******e
发帖数: 2181
40
来自主题: EE版 - ultra low frequency amplifier
Thank you upstairs!
Can I increase the input capacitor to 22 uF so that the impedience for low
frequency attenuates? The original input capacitor was 1 uF.
f*****0
发帖数: 489
41
来自主题: EE版 - 超高速整流电路求助
it is hard to find an opamp good for 10mhz, :).
the high voltage isn't an issue: you can use two resistors to attenuate it
down to a reasonable level. let's say 50vp.
then use a 1n4148 (with a resitor in serial) half wave rectification into a
small mica, ceramic or polyester capacitor (anything bigger than 1n will do)
. you will not be able to find a big ceramic or mica capacitor but since you
are running at 10mhz, you don't need a big capacitor to filter out the half
waves.
the whole thing shou
w*******e
发帖数: 16
42
来自主题: EE版 - 一道通信原理的题目。
noise power at receiver = 1e-5 watts = 10log10(1e-5) = -50dB
minimum signal power required at receiver = -50+14=-36dB
transmit power = 1.5 watts = 10log10(1.5) = 1.76dB
signal attenuation by cable is 0.7L dB
therefore, 1.76 + 13 - 0.7L = -36, L = 72.5(km)
F*********n
发帖数: 52
43
请问,如果射频放大器的增益(gain)还可以,大概15dB,但是输入匹配(input
matching)比较差,大概是-3dB,其对系统的影响是什么?
说说偶的理解,如果输入匹配差的话,相当部分的射频能量会反射回输入的路径,从而
增强了干扰,以及降低稳定性。
但是如果放大器的前端是一个输出匹配很好的可变衰减器(attenuator),是不是反射的
能量会大部分被吸收,从而减低了对系统的影响?
b*******2
发帖数: 2121
44
恩,这几个我都在linear website request sample了. 在等待shipping 中.
可是感觉还是有点达不到我需要的要求.希望会work吧..
我需要bandwidth 非常非常的narrow.
我最开始找的是LTC1164-8, 50dB Attenuation at ±4% of Center Frequency. 这是
我最想要的. 可是linear 网站上没有卖的了,其他网站也没看到,好像不生产了.
不知道还有没有其他推荐?
多谢

blocks?
band
z*****n
发帖数: 7639
45
yes, passing through some foliage gives attenuations.
How much it is depends on the thickness of
leaves and trees.
n******h
发帖数: 2544
46
来自主题: EE版 - 防辐射服解析
"所以这个铜网还得接地,走到哪得拖根尾巴。"
Wiki skin-effect. High-frequency energy will attenuate very fast in
conductor. Ghz signal can't penetrate 10um metal.
g******u
发帖数: 3060
47
来自主题: EE版 - 防辐射服解析
it will attenuate, but the radiation is a continuous effect not a one time
shot.
s*****g
发帖数: 66
48
应该是吧,这里的gain就是attenuation了
x***y
发帖数: 830
49

10G,基本上很难出方波,harmonic attenuation太厉害。
Z**n
发帖数: 95
50
电子工程与科学集数学,物理,化学,生物, 机械, 材料之大成。 论坛里的码工码农
们应当算在其中的“蓝领”大军这一支里而已,很庞大也很重要,由比尔-盖慈Steve
Jobs们领军。
实际上,家喻户晓的“白领”师匠也很多。这里所列的几位,其辉煌业绩应当是远远超
越了只是在Nature, Physics review上发多少篇文章。
1. 愛因斯坦 (Albert Einstein), 因研究光电效应之成果獲1921年諾貝爾物理學獎
光电效应: 电磁波入射到物体表面导致其电导率变化的现象,或电磁波辐射入射到物
体表面导致其内部产生电动势的现象. 1887年,德國物理學者海因里希•赫茲發
現,照射紫外線於金屬電極可以幫助產生電火花。1905年,阿爾伯特•愛因斯坦
發表論文對於光電效應實驗數據給出解釋,他主張這是光能量負載於離散量子包的結果
。這突破性理論是量子力學建成的重要因素。由於「他對理論物理學的成就,特別是光
電效應定律的發現」,愛因斯坦獲頒1921年諾貝爾物理學獎。
早年,愛因斯坦並未依照其父親的意願讀電機工程學,而是依他家一好友的建議於1895
年申請了瑞... 阅读全帖
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