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   604614篇
  免费   8654篇
  国内免费   2474篇
化学   328181篇
晶体学   8786篇
力学   26016篇
综合类   72篇
数学   73691篇
物理学   178996篇
  2021年   5000篇
  2020年   5697篇
  2019年   6112篇
  2018年   7948篇
  2017年   7824篇
  2016年   12015篇
  2015年   7748篇
  2014年   11548篇
  2013年   27731篇
  2012年   22215篇
  2011年   26976篇
  2010年   18811篇
  2009年   18455篇
  2008年   24805篇
  2007年   24686篇
  2006年   22929篇
  2005年   20620篇
  2004年   18753篇
  2003年   16430篇
  2002年   16127篇
  2001年   17816篇
  2000年   13574篇
  1999年   10482篇
  1998年   8766篇
  1997年   8493篇
  1996年   8369篇
  1995年   7391篇
  1994年   7386篇
  1993年   7200篇
  1992年   7926篇
  1991年   7935篇
  1990年   7578篇
  1989年   7333篇
  1988年   7237篇
  1987年   7106篇
  1986年   6823篇
  1985年   8996篇
  1984年   9106篇
  1983年   7400篇
  1982年   7619篇
  1981年   7409篇
  1980年   6854篇
  1979年   7391篇
  1978年   7711篇
  1977年   7637篇
  1976年   7573篇
  1975年   7025篇
  1974年   7100篇
  1973年   7091篇
  1972年   5190篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
51.
Svetlakova  A. V.  Mendez  M. Sanchez  Tuchin  E. S.  Khodan  A. N.  Traore  M.  Azouani  R.  Kanaev  A.  Tuchin  V. V. 《Optics and Spectroscopy》2021,129(8):846-850
Optics and Spectroscopy - We study the photocatalytic activity of nanocomposites based on θ-phase alumina (Al2O3) with different TiO2 concentrations for heterogeneous photocatalysis and...  相似文献   
52.
Russian Chemical Bulletin - The N-methylation of primary carboxamides is based on two consecutive reactions. The silylation of the corresponding carboxamides with chloro(chloromethyl)dimethylsilane...  相似文献   
53.
Crystallography Reports - Electron backscattered diffraction (EBSD) has been used to analyze structures of natural minerals and artificial compounds for almost three decades. In recent years, it is...  相似文献   
54.
Optical and Quantum Electronics - Classification of hyperspectral image (HSI) is widely used for the study of remotely sensed images. Convolutional Neural Networks (CNNs) are one of the most...  相似文献   
55.
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   
56.
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   
57.
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   
58.
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   
59.
Crystallography Reports - The orientation of grains and the special boundaries formed by them in multicrystalline silicon has been studied by electron backscattered diffraction. It is found that...  相似文献   
60.
Theoretical and Mathematical Physics - The fractional derivative method is used to take wave dispersion into account in the wave equation when describing the propagation of gravitational soliton...  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