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   8978篇
  免费   284篇
  国内免费   11篇
化学   4383篇
晶体学   85篇
力学   229篇
数学   2156篇
物理学   2420篇
  2021年   107篇
  2020年   126篇
  2019年   119篇
  2018年   187篇
  2017年   172篇
  2016年   362篇
  2015年   320篇
  2014年   355篇
  2013年   655篇
  2012年   455篇
  2011年   550篇
  2010年   348篇
  2009年   296篇
  2008年   308篇
  2007年   281篇
  2006年   202篇
  2005年   142篇
  2004年   167篇
  2003年   166篇
  2002年   141篇
  2001年   126篇
  2000年   144篇
  1999年   122篇
  1998年   115篇
  1997年   107篇
  1996年   102篇
  1995年   85篇
  1994年   90篇
  1993年   87篇
  1992年   87篇
  1991年   77篇
  1990年   89篇
  1989年   76篇
  1988年   80篇
  1987年   72篇
  1986年   68篇
  1985年   97篇
  1984年   106篇
  1983年   72篇
  1982年   92篇
  1981年   97篇
  1980年   82篇
  1979年   99篇
  1978年   90篇
  1977年   80篇
  1976年   100篇
  1975年   95篇
  1974年   91篇
  1973年   72篇
  1968年   74篇
排序方式: 共有9273条查询结果,搜索用时 68 毫秒
1.
Reactivity studies of the GeII→B complex L(Cl)Ge⋅BH3 ( 1 ; L=2-Et2NCH2-4,6-tBu2-C6H2) were performed to determine the effect on the GeII→B donation. N-coordinated compounds L(OtBu)Ge⋅BH3 ( 2 ) and [LGe⋅BH3]2 ( 3 ) were prepared. The possible tuning of the GeII→B interaction was proved experimentally, yielding compounds 1-PPh2-8-(LGe)-C10H6 ( 4 ) and L(Cl)Ge⋅GaCl3 ( 5 ) without a GeII→B interaction. In 5 , an unprecedented GeII→Ga coordination was revealed. The experimental results were complemented by a theoretical study focusing on the bonding in 1 − 5 . The different strength of the GeII→E (E=B, Ga) donation was evaluated by using energy decomposition analysis. The basicity of different L(X)Ge groups through proton affinity is also assessed.  相似文献   
2.
Central European Journal of Operations Research - Digital competences are among the most important competences in modern society, with the education system playing a key role in the acquisition of...  相似文献   
3.
4.
5.
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam...  相似文献   
6.
The nonlinear frequency response analysis (NFRA) can be seen as an extension of electrochemical impedance spectroscopy. NFRA gives a full and detailed representation of the system response and can establish a connection between model parameters and the experimentally observed phenomena. In this article, different theoretical NFRA approaches and the most recent application examples are discussed. A simple electrochemical example is used to showcase the benefits and disadvantages of analyzing the system response by using different approaches. In addition, it was shown how to extract experimental harmonic values and analyze them.  相似文献   
7.
8.
Summary The baseline separation of 23 dansylated amino acids (including 3 didansylated species) is reported. Lowering of the analysis temperature and fine control of the surfactant concentration were essential in obtaining this result. Calibration graphs with good linearity were obtained.  相似文献   
9.
10.
This paper attempts to develop a theory of sufficiency in the setting of non-commutative algebras parallel to the ideas in classical mathematical statistics. Sufficiency of a coarse-graining means that all information is extracted about the mutual relation of a given family of states. In the paper sufficient coarse-grainings are characterized in several equivalent ways and the non-commutative analogue of the factorization theorem is obtained. As an application we discuss exponential families. Our factorization theorem also implies two further important results, previously known only in finite Hilbert space dimension, but proved here in generality: the Koashi-Imoto theorem on maps leaving a family of states invariant, and the characterization of the general form of states in the equality case of strong subadditivity. Supported by the EU Research Training Network Quantum Probability with Applications to Physics, Information Theory and Biology and Center of Excellence SAS Physics of Information I/2/2005. Supported by the Hungarian grant OTKA T032662  相似文献   
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