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   5541篇
  免费   606篇
  国内免费   1230篇
化学   4203篇
晶体学   25篇
力学   206篇
综合类   20篇
数学   1488篇
物理学   1435篇
  2024年   2篇
  2023年   224篇
  2022年   227篇
  2021年   227篇
  2020年   279篇
  2019年   193篇
  2018年   222篇
  2017年   241篇
  2016年   253篇
  2015年   280篇
  2014年   384篇
  2013年   458篇
  2012年   564篇
  2011年   538篇
  2010年   405篇
  2009年   412篇
  2008年   354篇
  2007年   352篇
  2006年   323篇
  2005年   232篇
  2004年   173篇
  2003年   135篇
  2002年   126篇
  2001年   145篇
  2000年   99篇
  1999年   94篇
  1998年   49篇
  1997年   52篇
  1996年   39篇
  1995年   38篇
  1994年   38篇
  1993年   28篇
  1992年   38篇
  1991年   39篇
  1990年   18篇
  1989年   20篇
  1988年   13篇
  1987年   13篇
  1986年   22篇
  1985年   17篇
  1984年   5篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1979年   2篇
排序方式: 共有7377条查询结果,搜索用时 78 毫秒
1.
Xu  Yifan  Zhang  Hehe  Ding  Tangjing  Tian  Ruiqi  Sun  Dongmei  Wang  Ming-Sheng  Zhou  Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume...  相似文献   
2.
Science China Mathematics - In this paper, we obtain a necessary and sufficient condition for a U(n)-invariant complex Finsler metric F on domains in ?n to be strongly convex, which also...  相似文献   
3.
We use the machinery of categorified Jones-Wenzl projectors to construct a categorification of a type A Reshetikhin-Turaev invariant of oriented framed tangles where each strand is labelled by an arbitrary finite-dimensional representation. As a special case, we obtain a categorification of the coloured Jones polynomial of links.  相似文献   
4.
5.
6.
From Abies nukiangensis, two novel 13,14-seco-abietane diterpenes, nukiangendines A (1) and B (2) were isolated. Their relative structures were determined by extensive NMR and HRMS spectroscopic analysis. The absolute configuration of 1 was established by ECD calculations. Compound 1 showed significant anti-hepatitis C virus (HCV) effects.  相似文献   
7.
The N–N bond is present in many important organic compounds, such as hydrazines, pyrazoles, azos, etc. Many methods based on transition metal catalyzed N–N coupling or functionalization of hydrazine have been reported for the synthesis of N–N containing organic compounds. In recent years, electrochemical dehydrogenative N–H/N–H coupling has become a powerful tool for the construction of N–N bearing organic compounds. The electrochemical methods employ electrons as traceless redox reagents instead of chemicals and produce hydrogen as the only byproduct. In this review, we summarize the recent advances in the electrochemical dehydrogenative N–H/N–H coupling reactions with focus on the mechanistic insights and synthetic applications of these transformations.  相似文献   
8.
9.
10.
In this paper we establish the characterization of the weighted BMO via two weight commutators in the settings of the Neumann Laplacian ΔN+ on the upper half space R+n and the reflection Neumann Laplacian ΔN on Rn with respect to the weights associated to ΔN+ and ΔN respectively. This in turn yields a weak factorization for the corresponding weighted Hardy spaces, where in particular, the weighted class associated to ΔN is strictly larger than the Muckenhoupt weighted class and contains non-doubling weights. In our study, we also make contributions to the classical Muckenhoupt–Wheeden weighted Hardy space (BMO space respectively) by showing that it can be characterized via the area function (Carleson measure respectively) involving the semigroup generated by the Laplacian on Rn and that the duality of these weighted Hardy and BMO spaces holds for Muckenhoupt Ap weights with p(1,2] while the previously known related results cover only p(1,n+1n]. We also point out that this two weight commutator theorem might not be true in the setting of general operators L, and in particular we show that it is not true when L is the Dirichlet Laplacian ΔD+ on R+n.  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