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   78138篇
  免费   2370篇
  国内免费   493篇
化学   48029篇
晶体学   496篇
力学   1449篇
综合类   35篇
数学   13640篇
物理学   17352篇
  2023年   454篇
  2021年   1017篇
  2020年   1105篇
  2019年   1139篇
  2018年   1374篇
  2017年   1274篇
  2016年   2414篇
  2015年   2082篇
  2014年   2221篇
  2013年   4736篇
  2012年   4415篇
  2011年   4582篇
  2010年   3131篇
  2009年   2805篇
  2008年   4058篇
  2007年   3857篇
  2006年   3451篇
  2005年   3337篇
  2004年   2930篇
  2003年   2554篇
  2002年   2319篇
  2001年   1772篇
  2000年   1663篇
  1999年   1139篇
  1998年   876篇
  1997年   826篇
  1996年   1002篇
  1995年   849篇
  1994年   907篇
  1993年   816篇
  1992年   811篇
  1991年   736篇
  1990年   785篇
  1989年   626篇
  1988年   598篇
  1987年   593篇
  1986年   551篇
  1985年   784篇
  1984年   783篇
  1983年   596篇
  1982年   611篇
  1981年   581篇
  1980年   533篇
  1979年   494篇
  1978年   461篇
  1977年   523篇
  1976年   499篇
  1975年   419篇
  1974年   420篇
  1973年   437篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Applications of Mathematics - Proper traffic simulation of electric vehicles, which draw energy from overhead wires, requires adequate modeling of traction infrastructure. Such vehicles include...  相似文献   
2.
Set-Valued and Variational Analysis - In a Hilbert framework ℌ, we study the convergence properties of a Newton-like inertial dynamical system governed by a general maximally monotone...  相似文献   
3.
4.
Archiv der Mathematik - In this note, we introduce a criterion to detect vanishing of essential algebras of a Green biset functor by means of morphisms. We introduce the inflation morphism and...  相似文献   
5.
Set-Valued and Variational Analysis - The production correspondence associated with a technology maps every input vector into the set of output vectors that may be obtained by means of those...  相似文献   
6.
Journal of Radioanalytical and Nuclear Chemistry - The mass fractions of V, Cr, Co, Ni, Cu, Zn, As, Br, Mo, Cd, W, Hg, and Pb in soil of the Czech dump-side were measured by instrumental neutron...  相似文献   
7.
Pentafluorosulfanyl (SF5)-containing compounds and corresponding analogs are a highly valuable class of fluorine-containing building blocks owing to their unique properties. The reason for that is the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S−F, and C−SF5 bond formation as well as the use of SF5-containing building blocks embody a “stairway-to-heaven” loophole in the synthesis of otherwise-inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015.  相似文献   
8.
This review summarizes recent progress in understanding the oxygen reduction and evolution reactions at the lanthanum strontium manganite electrode of a high-temperature solid oxide cell. Information provided here is put into the perspective of the defect chemistry of lanthanum strontium manganite and its impact on the electrode reaction mechanisms itself. After summarizing recent views on the oxygen reduction reaction mechanism, the focus turns to the oxygen evolution reaction, which is significantly less treated in the literature. A combination of the information in the literature on both reactions was the basis for modified reaction mechanism of the oxygen evolution reaction to be proposed under consideration of recent experimental observations and theoretical findings.  相似文献   
9.
Controlling redox activity of judiciously appended redox units on a photo-sensitive molecular core is an effective strategy for visible light energy harvesting and storage. The first example of a photosensitizer - electron donor coordination compound in which the photoinduced electron transfer step is used for light to electrical energy conversion and storage is reported. A photo-responsive Ru-diimine module conjugated with redox-active catechol groups in [Ru(II)(phenanthroline-5,6-diolate)3]4− photosensitizer can mediate photoinduced catechol to dione oxidation in the presence of a sacrificial electron acceptor or at the surface of an electrode. Under potentiostatic condition, visible light triggered current density enhancement confirmed the light harvesting ability of this photosensitizer. Upon implementation in galvanostatic charge-discharge of a Li battery configuration, the storage capacity was found to be increased by 100 %, under 470 nm illumination with output power of 4.0 mW/cm−2. This proof-of-concept molecular system marks an important milestone towards a new generation of molecular photo-rechargeable materials.  相似文献   
10.
Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,...  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