全文获取类型
收费全文 | 6500篇 |
免费 | 256篇 |
国内免费 | 46篇 |
专业分类
化学 | 4796篇 |
晶体学 | 24篇 |
力学 | 207篇 |
数学 | 897篇 |
物理学 | 878篇 |
出版年
2023年 | 62篇 |
2022年 | 77篇 |
2021年 | 126篇 |
2020年 | 118篇 |
2019年 | 148篇 |
2018年 | 91篇 |
2017年 | 82篇 |
2016年 | 197篇 |
2015年 | 165篇 |
2014年 | 205篇 |
2013年 | 370篇 |
2012年 | 465篇 |
2011年 | 500篇 |
2010年 | 271篇 |
2009年 | 239篇 |
2008年 | 425篇 |
2007年 | 435篇 |
2006年 | 391篇 |
2005年 | 362篇 |
2004年 | 339篇 |
2003年 | 301篇 |
2002年 | 253篇 |
2001年 | 88篇 |
2000年 | 81篇 |
1999年 | 65篇 |
1998年 | 57篇 |
1997年 | 62篇 |
1996年 | 75篇 |
1995年 | 49篇 |
1994年 | 37篇 |
1993年 | 27篇 |
1992年 | 32篇 |
1991年 | 34篇 |
1990年 | 36篇 |
1989年 | 27篇 |
1988年 | 18篇 |
1986年 | 21篇 |
1985年 | 28篇 |
1984年 | 40篇 |
1983年 | 29篇 |
1982年 | 39篇 |
1981年 | 25篇 |
1980年 | 40篇 |
1979年 | 24篇 |
1978年 | 30篇 |
1977年 | 37篇 |
1976年 | 29篇 |
1975年 | 31篇 |
1974年 | 22篇 |
1973年 | 21篇 |
排序方式: 共有6802条查询结果,搜索用时 46 毫秒
241.
242.
243.
Catalytic Enantioselective CH Functionalization of Alcohols by Redox‐Triggered Carbonyl Addition: Borrowing Hydrogen,Returning Carbon
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
John M. Ketcham Inji Shin T. Patrick Montgomery Prof. Michael J. Krische 《Angewandte Chemie (International ed. in English)》2014,53(35):9142-9150
The use of alcohols and unsaturated reactants for the redox‐triggered generation of nucleophile–electrophile pairs represents a broad, new approach to carbonyl addition chemistry. Discrete redox manipulations that are often required for the generation of carbonyl electrophiles and premetalated carbon‐centered nucleophiles are thus avoided. Based on this concept, a broad, new family of enantioselective C? C coupling reactions that are catalyzed by iridium or ruthenium complexes have been developed, which are summarized in this Minireview. 相似文献
244.
Patrick Ballard 《Journal of Elasticity》2013,110(1):33-61
The existence and uniqueness of an equilibrium solution to frictional contact problems involving a class of moving rigid obstacles is studied. At low friction coefficient values, the steady sliding frictional contact problem is uniquely solvable, thanks to the Lions-Stampacchia theorem on variational inequalities associated with a nonsymmetric coercive bilinear form. It is proved that the coerciveness of the bilinear form can be lost at some positive critical value of the friction coefficient, depending only on the geometry and the elastic properties of the body. An example presented here, shows that infinitely many solutions can be obtained when the friction coefficient is larger than the critical value. This result is paving the road towards a theory of jamming in terms of bifurcation in variational inequality. The particular case where the elastic body is an isotropic half-space is studied. The corresponding value of the critical friction coefficient is proved to be infinite in this case. In the particular case of the frictionless situation, our analysis incidentally unifies the approaches developed by Lions-Stampacchia (variational inequalities) and Hertz (harmonic analysis on the half-space) to contact problems in linear elasticity. 相似文献
245.
Dr. Patrick Feicht Dr. Johannes Biskupek Dr. Tatiana E. Gorelik Julian Renner Dr. Christian E. Halbig Maria Maranska Florian Puchtler Prof. Dr. Ute Kaiser Prof. Dr. Siegfried Eigler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(38):8955-8959
Synthesis and studies of graphite oxide started more than 150 years ago and turned into a boom by the measurements of the outstanding physical properties of graphene. A series of preparation protocols emanated trying to optimize the synthesis of graphene oxide in order to obtain a less defective material, as source for graphene. However, over-oxidation of the carbon framework hampered establishing structure-property relationships. Here, the fact that two different synthetic methods for graphene oxide preparation lead to very similar types of graphene oxide with a preserved graphene lattice is demonstrated. Either sodium chlorate in nitric acid (similar to Brodie's method) or potassium permanganate in sulfuric acid (similar to Hummers’ method) treatment are possible; however, reaction conditions must be controlled. With a preserved carbon lattice analytical differences between the samples relate to the altered on-plane functionality. Consequently, terming preparation protocols “according to Brodie's/Hummers’ method” is not sufficient. 相似文献
246.
Two-Photon-Induced CO-Releasing Molecules as Molecular Logic Systems in Solution,Polymers, and Cells
Dr. Vadde Ramu Dr. Gandra Upendar Reddy Dr. Jingjing Liu Patrick Hoffmann Dr. Rudrakant Sollapur Dr. Ralf Wyrwa Dr. Stephan Kupfer Prof. Dr. Christian Spielmann Dr. Sylvestre Bonnet Prof. Dr. Ute Neugebauer Dr. Alexander Schiller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8453-8458
Phototherapeutic applications of carbon monoxide (CO)-releasing molecules are limited because they require harmful UV and blue light for activation. We describe two-photon excitation with NIR light (800 nm)-induced CO-release from two MnI tricarbonyl complexes bearing 1,8-naphthalimide units ( 1 , 2 ). Complex 2 behaves as a logic OR gate in solution, nonwovens, and in HeLa cells. CO release, indicated by fluorescence enhancement, was detected in solution, nonwoven, and HeLa cells by single- (405 nm) and two-photon (800 nm) excitation. The photophysical properties of 1 and 2 have been measured and supported by DFT and TDDFT quantum chemical calculations. Both photoCORMs are stable in the dark in solution and noncytotoxic, leading to promising applications as phototherapeutics with NIR light. 相似文献
247.
248.
249.