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   155402篇
  免费   1633篇
  国内免费   439篇
化学   85677篇
晶体学   2468篇
力学   6337篇
综合类   3篇
数学   15205篇
物理学   47784篇
  2021年   1116篇
  2020年   1273篇
  2019年   1325篇
  2018年   1708篇
  2017年   1751篇
  2016年   2670篇
  2015年   1686篇
  2014年   2495篇
  2013年   6534篇
  2012年   5187篇
  2011年   6377篇
  2010年   4431篇
  2009年   4428篇
  2008年   6178篇
  2007年   5916篇
  2006年   5793篇
  2005年   5341篇
  2004年   4768篇
  2003年   4423篇
  2002年   4323篇
  2001年   5682篇
  2000年   4092篇
  1999年   3170篇
  1998年   2199篇
  1997年   2310篇
  1996年   2208篇
  1995年   1992篇
  1994年   2012篇
  1993年   1829篇
  1992年   2319篇
  1991年   2393篇
  1990年   2233篇
  1989年   2178篇
  1988年   2164篇
  1987年   2177篇
  1986年   1979篇
  1985年   2521篇
  1984年   2531篇
  1983年   2029篇
  1982年   2045篇
  1981年   1899篇
  1980年   1877篇
  1979年   2146篇
  1978年   2226篇
  1977年   2171篇
  1976年   2089篇
  1975年   1959篇
  1974年   1943篇
  1973年   1976篇
  1972年   1295篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
21.
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   
22.
23.
Profiling engineered data with robust mining methods continues attracting attention in knowledge engineering systems. The purpose of this article is to propose a simple technique that deals with non-linear multi-factorial multi-characteristic screening suitable for knowledge discovery studies. The method is designed to proactively seek and quantify significant information content in engineered mini-datasets. This is achieved by deploying replicated fractional-factorial sampling schemes. Compiled multi-response data are converted to a single master-response effectuated by a series of distribution-free transformations and multi-compressed data fusions. The resulting amalgamated master response is deciphered by non-linear multi-factorial stealth stochastics intended for saturated schemes. The stealth properties of our method target processing datasets which might be overwhelmed by a lack of knowledge about the nature of reference distributions at play. Stealth features are triggered to overcome restrictions regarding the data normality conformance, the effect sparsity assumption and the inherent collapse of the ‘unexplainable error’ connotation in saturated arrays. The technique is showcased by profiling four ordinary controlling factors that influence webpage content performance by collecting data from a commercial browser monitoring service on a large scale web host. The examined effects are: (1) the number of Cascading Style Sheets files, (2) the number of JavaScript files, (3) the number of Image files, and (4) the Domain Name System Aliasing. The webpage performance level was screened against three popular characteristics: (1) the time to first visual, (2) the total loading time, and (3) the customer satisfaction. Our robust multi-response data mining technique is elucidated for a ten-replicate run study dictated by an L9(34) orthogonal array scheme where any uncontrolled noise embedded contribution has not been necessarily excluded.  相似文献   
24.
25.
Russian Chemical Bulletin - Quantum chemical calculations and a comparative analysis of Raman spectra of 3,4,5-triphenyl-1-propyl-1,2-diphosphole (1),...  相似文献   
26.
27.
Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups...  相似文献   
28.
29.
30.
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