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   48625篇
  免费   11822篇
  国内免费   3205篇
化学   50361篇
晶体学   543篇
力学   1302篇
综合类   131篇
数学   3424篇
物理学   7891篇
  2024年   47篇
  2023年   320篇
  2022年   559篇
  2021年   668篇
  2020年   1751篇
  2019年   3112篇
  2018年   1452篇
  2017年   1108篇
  2016年   3925篇
  2015年   4097篇
  2014年   4173篇
  2013年   5053篇
  2012年   4205篇
  2011年   3592篇
  2010年   3775篇
  2009年   3724篇
  2008年   3241篇
  2007年   2630篇
  2006年   2142篇
  2005年   2217篇
  2004年   1908篇
  2003年   1674篇
  2002年   2346篇
  2001年   1680篇
  2000年   1583篇
  1999年   599篇
  1998年   252篇
  1997年   208篇
  1996年   215篇
  1995年   162篇
  1994年   181篇
  1993年   150篇
  1992年   141篇
  1991年   111篇
  1990年   99篇
  1989年   92篇
  1988年   58篇
  1987年   55篇
  1986年   50篇
  1985年   61篇
  1984年   46篇
  1983年   26篇
  1982年   13篇
  1981年   21篇
  1979年   18篇
  1978年   20篇
  1977年   9篇
  1976年   9篇
  1975年   13篇
  1973年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Fan  K.  Lu  R. S.  Liang  K. K.  Hou  Z. C. 《High Energy Chemistry》2022,56(4):264-269
High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was...  相似文献   
2.
International Journal of Theoretical Physics - In this work, we give an analytical derivation of the reduced density matrix between two qubits in a cavity field, which is described by the quantum...  相似文献   
3.
4.
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst.  相似文献   
5.
6.
In this paper, let (Mn,g,dμ) be n-dimensional noncompact metric measure space which satisfies Poincaré inequality with some Ricci curvature condition. We obtain a Liouville theorem for positive weak solutions to weighted p-Lichnerowicz equation
p,fv+cvσ=0,
where c0,m>n1,1<p<m?1+(m?1)(m+3)2,σp?1 are real constants.  相似文献   
7.
The development of high‐surface‐area carbon electrodes with a defined pore size distribution and the incorporation of pseudo‐active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano‐onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission‐ and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g?1 for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g?1 for the CNOs/Ppy bilayer (electrochemical deposition).  相似文献   
8.
A two‐step synthesis of structurally diverse pyrrole‐containing bicyclic systems is reported. ortho‐Nitro‐haloarenes coupled with vinylic N‐methyliminodiacetic acid (MIDA) boronates generate ortho‐vinyl‐nitroarenes, which undergo a “metal‐free” nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex “drug‐like” molecules. Interestingly, an ortho‐nitro‐allylarene derivative furnished a cyclic β‐aminophosphonate motif.  相似文献   
9.
10.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  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