全文获取类型
收费全文 | 480612篇 |
免费 | 10437篇 |
国内免费 | 4426篇 |
专业分类
化学 | 268909篇 |
晶体学 | 7047篇 |
力学 | 20736篇 |
综合类 | 228篇 |
数学 | 54897篇 |
物理学 | 143658篇 |
出版年
2020年 | 3890篇 |
2019年 | 3835篇 |
2018年 | 3870篇 |
2017年 | 3700篇 |
2016年 | 6920篇 |
2015年 | 5700篇 |
2014年 | 7664篇 |
2013年 | 21810篇 |
2012年 | 16611篇 |
2011年 | 20249篇 |
2010年 | 13003篇 |
2009年 | 12807篇 |
2008年 | 18137篇 |
2007年 | 18277篇 |
2006年 | 17453篇 |
2005年 | 15878篇 |
2004年 | 14179篇 |
2003年 | 12503篇 |
2002年 | 12254篇 |
2001年 | 14250篇 |
2000年 | 11053篇 |
1999年 | 9085篇 |
1998年 | 7279篇 |
1997年 | 7151篇 |
1996年 | 7160篇 |
1995年 | 6560篇 |
1994年 | 6233篇 |
1993年 | 5884篇 |
1992年 | 6681篇 |
1991年 | 6387篇 |
1990年 | 6076篇 |
1989年 | 5927篇 |
1988年 | 6076篇 |
1987年 | 5804篇 |
1986年 | 5520篇 |
1985年 | 7754篇 |
1984年 | 7830篇 |
1983年 | 6429篇 |
1982年 | 6868篇 |
1981年 | 6850篇 |
1980年 | 6491篇 |
1979年 | 6753篇 |
1978年 | 6931篇 |
1977年 | 6818篇 |
1976年 | 6709篇 |
1975年 | 6488篇 |
1974年 | 6290篇 |
1973年 | 6470篇 |
1972年 | 3916篇 |
1968年 | 3369篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Haixing Guan Qianwen Zhang Prof. Dr. Patrick J. Walsh Prof. Dr. Jianyou Mao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(13):5210-5215
A unique nickel/organic photoredox co-catalyzed asymmetric reductive cross-coupling between α-chloro esters and aryl iodides is developed. This cross-electrophile coupling reaction employs an organic reductant (Hantzsch ester), whereas most reductive cross-coupling reactions use stoichiometric metals. A diverse array of valuable α-aryl esters is formed under these conditions with high enantioselectivities (up to 94 %) and good yields (up to 88 %). α-Aryl esters represent an important family of nonsteroidal anti-inflammatory drugs. This novel synergistic strategy expands the scope of Ni-catalyzed reductive asymmetric cross-coupling reactions. 相似文献
32.
Rongrong Li Hongjie Peng Qingping Wu Xuejun Zhou Jiang He Hangjia Shen Minghui Yang Chilin Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):12227-12236
Herein, we propose the construction of a sandwich-structured host filled with continuous 2D catalysis–conduction interfaces. This MoN-C-MoN trilayer architecture causes the strong conformal adsorption of S/Li2Sx and its high-efficiency conversion on the two-sided nitride polar surfaces, which are supplied with high-flux electron transfer from the buried carbon interlayer. The 3D self-assembly of these 2D sandwich structures further reinforces the interconnection of conductive and catalytic networks. The maximized exposure of adsorptive/catalytic planes endows the MoN-C@S electrode with excellent cycling stability and high rate performance even under high S loading and low host surface area. The high conductivity of this trilayer texture does not compromise the capacity retention after the S content is increased. Such a job-synergistic mode between catalytic and conductive functions guarantees the homogeneous deposition of S/Li2Sx, and avoids thick and devitalized accumulation (electrode passivation) even after high-rate and long-term cycling. 相似文献
33.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
34.
35.
36.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle... 相似文献
37.
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
38.
39.
40.