首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   196890篇
  免费   2558篇
  国内免费   1259篇
化学   89382篇
晶体学   3101篇
力学   7278篇
综合类   85篇
数学   19741篇
物理学   56362篇
无线电   24758篇
  2021年   1455篇
  2020年   1661篇
  2019年   1791篇
  2018年   2255篇
  2017年   2335篇
  2016年   3520篇
  2015年   2148篇
  2014年   3535篇
  2013年   8379篇
  2012年   6322篇
  2011年   7510篇
  2010年   5720篇
  2009年   5945篇
  2008年   7646篇
  2007年   7687篇
  2006年   7308篇
  2005年   6696篇
  2004年   6230篇
  2003年   5619篇
  2002年   5482篇
  2001年   6224篇
  2000年   4853篇
  1999年   3879篇
  1998年   3304篇
  1997年   3146篇
  1996年   2990篇
  1995年   2825篇
  1994年   2728篇
  1993年   2669篇
  1992年   2949篇
  1991年   2884篇
  1990年   2769篇
  1989年   2642篇
  1988年   2609篇
  1987年   2369篇
  1986年   2219篇
  1985年   2873篇
  1984年   2925篇
  1983年   2583篇
  1982年   2671篇
  1981年   2474篇
  1980年   2454篇
  1979年   2562篇
  1978年   2594篇
  1977年   2523篇
  1976年   2594篇
  1975年   2478篇
  1974年   2441篇
  1973年   2634篇
  1972年   1711篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
12.
Journal of Mathematical Chemistry - The analytical solutions of an asymmetric double well potential $$V(x)=a\, x^2-b\, x^3+c\, x^4$$ are found to be a triconfluent Heun function $$H_{T}(\alpha ,...  相似文献   
13.
Journal of Applied and Industrial Mathematics - We study the problem of optimal location of the ambulance fleet at the base stations. The objective is to minimize the average waiting time for...  相似文献   
14.
A liquid dewetting method for the determination of the viscoelastic properties of ultrathin polymer films has been extended to study thickness effects on the properties of ultrathin polycarbonate (PC) films. PC films with film thicknesses ranging from 4 to 299 nm were placed on glycerol at temperatures from below the macroscopic glass transition temperature (Tg) to above it with the dewetting responses being monitored. It is found that the isothermal creep results for films of the same thickness, but dewetted at different temperatures can be superposed into one master curve, which is consistent with the fact of PC being a thermorheologically simple material. Furthermore, the results show that the Tg of PC thin films is thickness dependent, but the dependence is weaker than the results for freely standing films and similar to literature data for PC films supported on rigid substrates. It was also found that the rubbery plateau region for the PC films stiffens dramatically, but still less than what has been observed for freely standing polycarbonate films. The rubbery stiffening is discussed in terms of a recently reported model that relates macroscopic segmental dynamics with the stiffening. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1559–1566  相似文献   
15.
The design of new solid-state proton-conducting materials is a great challenge for chemistry and materials science. Herein, a new anionic porphyrinylphosphonate-based MOF ( IPCE-1Ni ), which involves dimethylammonium (DMA) cations for charge compensation, is reported. As a result of its unique structure, IPCE-1Ni exhibits one of the highest value of the proton conductivity among reported proton-conducting MOF materials based on porphyrins (1.55×10−3 S cm−1 at 75 °C and 80 % relative humidity).  相似文献   
16.
Multidimensional Systems and Signal Processing - The paper is devoted to the development of the octonion Fourier transform (OFT) theory initiated in 2011 in articles by Hahn and Snopek. It is also...  相似文献   
17.
18.
19.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  相似文献   
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号