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   91304篇
  免费   5130篇
  国内免费   3691篇
化学   55361篇
晶体学   890篇
力学   3455篇
综合类   247篇
数学   18203篇
物理学   21969篇
  2023年   621篇
  2022年   1120篇
  2021年   1287篇
  2020年   1546篇
  2019年   1541篇
  2018年   2371篇
  2017年   2564篇
  2016年   2761篇
  2015年   2523篇
  2014年   2834篇
  2013年   4258篇
  2012年   7480篇
  2011年   7174篇
  2010年   4823篇
  2009年   4391篇
  2008年   4707篇
  2007年   4401篇
  2006年   4239篇
  2005年   7606篇
  2004年   6567篇
  2003年   4507篇
  2002年   2668篇
  2001年   1498篇
  2000年   1174篇
  1999年   1152篇
  1998年   1003篇
  1997年   923篇
  1996年   958篇
  1995年   739篇
  1994年   775篇
  1993年   697篇
  1992年   794篇
  1991年   707篇
  1990年   607篇
  1989年   507篇
  1988年   475篇
  1987年   405篇
  1986年   363篇
  1985年   567篇
  1984年   459篇
  1983年   370篇
  1982年   429篇
  1981年   345篇
  1980年   350篇
  1979年   323篇
  1978年   290篇
  1977年   264篇
  1976年   323篇
  1975年   255篇
  1974年   238篇
排序方式: 共有10000条查询结果,搜索用时 28 毫秒
1.
Lin  Yu  Wu  Yeyu  Tan  Xuecai  Wu  Jiawen  Huang  Kejing  Mi  Yan  Ou  Panpan  Wei  Fucun 《Journal of Solid State Electrochemistry》2022,26(4):959-971
Journal of Solid State Electrochemistry - An ultrasensitive “signal-off–on” electrochemiluminescence (ECL) biosensor is constructed based on f1-TiO2/g-C3N4/PDA for thrombin...  相似文献   
2.
Mathematical Programming - We provide a control-theoretic perspective on optimal tensor algorithms for minimizing a convex function in a finite-dimensional Euclidean space. Given a function...  相似文献   
3.
The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances. Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties.  相似文献   
4.
5.
6.
Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device.  相似文献   
7.
Secondary structures tend to be recognizable because they have repeating structural motifs, but mimicry of these does not have to follow such well-defined patterns. Bioinformatics studies to match side-chain orientations of a novel hydantoin triazole chemotype ( 1 ) to protein-protein interfaces revealed it tends to align well across parallel and antiparallel sheets, like rungs on a ladder. One set of these overlays was observed for the protein-protein interaction uPA⋅uPAR. Consequently, chemotype 1 was made with appropriate side-chains to mimic uPA at this interface. Biophysical assays indicate these compounds did in fact bind uPAR, and elicit cellular responses that affected invasion, migration, and wound healing.  相似文献   
8.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure.  相似文献   
9.
10.
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