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   371638篇
  免费   5323篇
  国内免费   1678篇
化学   205576篇
晶体学   5125篇
力学   14915篇
综合类   64篇
数学   42283篇
物理学   110676篇
  2020年   3156篇
  2019年   3212篇
  2018年   4185篇
  2017年   4227篇
  2016年   6563篇
  2015年   4457篇
  2014年   6299篇
  2013年   15703篇
  2012年   12833篇
  2011年   15735篇
  2010年   10879篇
  2009年   10622篇
  2008年   14951篇
  2007年   14853篇
  2006年   14041篇
  2005年   12793篇
  2004年   11285篇
  2003年   10124篇
  2002年   9950篇
  2001年   11720篇
  2000年   8851篇
  1999年   6597篇
  1998年   5082篇
  1997年   5140篇
  1996年   5121篇
  1995年   4590篇
  1994年   4653篇
  1993年   4468篇
  1992年   5091篇
  1991年   5107篇
  1990年   4813篇
  1989年   4668篇
  1988年   4590篇
  1987年   4556篇
  1986年   4337篇
  1985年   5721篇
  1984年   5740篇
  1983年   4775篇
  1982年   4991篇
  1981年   4573篇
  1980年   4360篇
  1979年   4739篇
  1978年   5053篇
  1977年   5078篇
  1976年   4990篇
  1975年   4595篇
  1974年   4695篇
  1973年   4773篇
  1972年   3451篇
  1971年   2767篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Journal of Analytical Chemistry - Silver nanoparticles modified with Eu3+ ions increase the intensity of the fluorescence signal by a factor of 125 in an analytical system containing doxycycline as...  相似文献   
22.
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...  相似文献   
23.
Journal of Radioanalytical and Nuclear Chemistry - In this paper a study for the selection of an NPE (nonylphenol ethoxylates)—free cocktail is discussed in order to be used for our routine...  相似文献   
24.
Radiophysics and Quantum Electronics - A well-known simplified model of turbulent convection from local sources of buoyancy and/or momentum acting for a short time has been developed and...  相似文献   
25.
Astrelin  V. T. 《Russian Physics Journal》2021,63(10):1728-1734
Russian Physics Journal - A solution for the one-dimensional Poisson problem for a layer on the surface of a plasma ion emitter is obtained. The case of plasma with a directed ion velocity greater...  相似文献   
26.
Fomenko  T. N. 《Mathematical Notes》2021,110(3-4):583-591
Mathematical Notes - The notion of a $$\lambda$$ -generalized-search multivalued functional on an $$f$$ -quasimetric space is introduced. An existence theorem for zeros of such functionals is...  相似文献   
27.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the...  相似文献   
28.
Chen  R. J.  Chen  W.  Kong  F. L. 《Analysis Mathematica》2022,48(1):19-28

Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.

  相似文献   
29.
Physics of the Solid State - The external factors which influence the ferromagnetic resonance (FMR) line width in bilayer (ferromagnet/antiferromagnet) exchange-biased systems are studied. The...  相似文献   
30.
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.  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