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   7518篇
  免费   238篇
  国内免费   24篇
化学   4993篇
晶体学   112篇
力学   176篇
数学   1041篇
物理学   1458篇
  2021年   71篇
  2020年   113篇
  2019年   90篇
  2018年   58篇
  2017年   54篇
  2016年   184篇
  2015年   165篇
  2014年   164篇
  2013年   299篇
  2012年   288篇
  2011年   372篇
  2010年   238篇
  2009年   224篇
  2008年   317篇
  2007年   318篇
  2006年   312篇
  2005年   284篇
  2004年   293篇
  2003年   235篇
  2002年   225篇
  2001年   147篇
  2000年   148篇
  1999年   119篇
  1998年   114篇
  1997年   111篇
  1996年   130篇
  1995年   112篇
  1994年   110篇
  1993年   110篇
  1992年   101篇
  1991年   85篇
  1990年   73篇
  1989年   118篇
  1988年   112篇
  1987年   118篇
  1986年   90篇
  1985年   83篇
  1984年   81篇
  1983年   89篇
  1982年   91篇
  1981年   107篇
  1980年   90篇
  1979年   93篇
  1978年   86篇
  1977年   81篇
  1976年   66篇
  1975年   59篇
  1974年   52篇
  1973年   62篇
  1970年   44篇
排序方式: 共有7780条查询结果,搜索用时 46 毫秒
991.
The outer automorphism group of a nest algebra is canonically isomorphic to the (spatial) automorphism group of the nest itself. The outer automorphism group of the associated quasitriangular algebra is canonically isomorphic to a group of “approximate” automorphisms of the nest. A simple proof that every derivation of a quasitriangular algebra is inner is obtained as a corollary.  相似文献   
992.
993.
994.
995.
996.
Summary The new selective and sensitive redox chemiluminescence detector (RCD), originally developed for gas chromatography, has been successfully interfaced with a capillary column supercritical fluid chromatograph. Interfacing the SFC-RCD was accomplished simply through utilization of the redox reaction chamber presently used for both capillary and packed column GC. The feasibility of this new separation-detection scheme was demonstrated with SFC chromatograms of antioxidant isomers and some compounds of biological relevance. Mobile phase compatibility and signal quenching are also discussed.
Chromatographie mit überkritischen fluiden phasen unter Verwendung der Redox-Chemiluminescenz-Detektion
  相似文献   
997.
A conjecture concerning vacuum correlations in axiomatic quantum field theory is proved. It is shown that this result can be applied both in the context of EPR-type experiments and Bell-type experiments.  相似文献   
998.
Measurements on complex materials are often hampered by the difficulties arising from the prerequisites to control sample uniformity. A new single- and multi-reflection ATR-accessory has been designed for the rapid analysis of many samples under extremely similar experimental conditions. This is performed by passing the ATR-unit, a horizontally mounted ZnSe-prism, by the IR-beam. It includes a gas-tight sample region. Thus, toxic material and even pathogenic bacteria may be measured under controlled conditions.  相似文献   
999.
The work function of regularly stepped tungsten single crystal planes has been investigated as function of terrace width and step orientation. The terraces were always formed by (110) planes. One set of samples exhibited step edges running parallel to the [001] direction but different terrace widths. Another set with almost equal terrace width showed step edges of different directions with correspondingly different edge structures. The work function measurements were performed using thermionic emission in the temperature range 2000–2800 K. The work function decreases linearly with step density for a given step orientation. Different step orientations give rise to slightly different work function reductions. The results are interpreted by attributing additional dipole moments to edge atoms. Different edge structures lead to different dipole moments. These findings are consistent with Smoluchowski's “smoothing effect” of the electron charge distribution caused by the structural arrangement of surface atoms. The temperature coefficient of the work function also depends strongly on step density and step orientation.  相似文献   
1000.
The change of the cohesive energy and the optical absorption spectra of small singly sized Hg clusters is discussed. The cohesive energy allows one to determine the different regimes of chemical bonding. The optical spectra show an abrupt transition to a collective, plasmon-like absorption as a function of increasing cluster size. The position of the one plasmon peak is: 1) independent of the charge state, 2) nearly independent of cluster size, and 3) agrees with that of the classical Mie plasmon calculated from the experimental dielectric constants. The width of the plasmon peaks is discussed. A strong influence of electronic correlations on the cluster size dependence of the oscillator strength is observed.  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