全文获取类型
收费全文 | 169896篇 |
免费 | 4787篇 |
国内免费 | 2766篇 |
专业分类
化学 | 94566篇 |
晶体学 | 2225篇 |
力学 | 7930篇 |
综合类 | 166篇 |
数学 | 17085篇 |
物理学 | 55477篇 |
出版年
2022年 | 1402篇 |
2021年 | 1620篇 |
2020年 | 1853篇 |
2019年 | 1819篇 |
2018年 | 2055篇 |
2017年 | 1966篇 |
2016年 | 3278篇 |
2015年 | 2358篇 |
2014年 | 3419篇 |
2013年 | 7511篇 |
2012年 | 6505篇 |
2011年 | 7867篇 |
2010年 | 5350篇 |
2009年 | 5296篇 |
2008年 | 6854篇 |
2007年 | 6773篇 |
2006年 | 6433篇 |
2005年 | 5845篇 |
2004年 | 5074篇 |
2003年 | 4413篇 |
2002年 | 4440篇 |
2001年 | 4789篇 |
2000年 | 3698篇 |
1999年 | 3014篇 |
1998年 | 2550篇 |
1997年 | 2475篇 |
1996年 | 2312篇 |
1995年 | 2180篇 |
1994年 | 2156篇 |
1993年 | 1922篇 |
1992年 | 2178篇 |
1991年 | 2272篇 |
1990年 | 2047篇 |
1989年 | 2027篇 |
1988年 | 1963篇 |
1987年 | 1820篇 |
1986年 | 1752篇 |
1985年 | 2235篇 |
1984年 | 2353篇 |
1983年 | 1921篇 |
1982年 | 2090篇 |
1981年 | 1982篇 |
1980年 | 1895篇 |
1979年 | 2031篇 |
1978年 | 2197篇 |
1977年 | 2067篇 |
1976年 | 2112篇 |
1975年 | 2019篇 |
1974年 | 2072篇 |
1973年 | 2060篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Laurens Kooijman Dr. Matthias Schuster Christian Baumann Simon Jurt Dr. Frank Löhr Dr. Boris Fürtig Prof. Dr. Peter Güntert Prof. Dr. Oliver Zerbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21151-21158
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR. 相似文献
23.
Dr. Yong-Sheng Wei Dr. Liming Sun Miao Wang Dr. Jinhua Hong Dr. Lianli Zou Hongwen Liu Dr. Yu Wang Dr. Mei Zhang Dr. Zheng Liu Prof. Yinwei Li Prof. Satoshi Horike Prof. Kazu Suenaga Prof. Qiang Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16147-16156
Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal–organic framework encapsulating a trinuclear FeIII2FeII complex (denoted as Fe3) within the channels, a well-defined nitrogen-doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII/CoII) via synthesizing isostructural trinuclear-complex precursors (Fe2Zn/Fe2Co), namely the “heteroatom modulator approach”, is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal–nitrogen moiety, clearly identified by direct transmission electron microscopy and X-ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal–metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities. 相似文献
24.
ABSTRACTThe Coupled-Cluster (CC) theory is one of the most successful high precision methods used to solve the stationary Schrödinger equation. In this article, we address the mathematical foundation of this theory with focus on the advances made in the past decade. Rather than solely relying on spectral gap assumptions (non-degeneracy of the ground state), we highlight the importance of coercivity assumptions – Gårding type inequalities – for the local uniqueness of the CC solution. Based on local strong monotonicity, different sufficient conditions for a local unique solution are suggested. One of the criteria assumes the relative smallness of the total cluster amplitudes (after possibly removing the single amplitudes) compared to the Gårding constants. In the extended CC theory the Lagrange multipliers are wave function parameters and, by means of the bivariational principle, we here derive a connection between the exact cluster amplitudes and the Lagrange multipliers. This relation might prove useful when determining the quality of a CC solution. Furthermore, the use of an Aubin–Nitsche duality type method in different CC approaches is discussed and contrasted with the bivariational principle. 相似文献
25.
Kazakova E. F. Dmitrieva N. E. Zvereva N. L. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):341-344
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the... 相似文献
26.
27.
28.
29.
Qin Yin Shou-Guo Wang Xiao-Wei Liang De-Wei Gao Jun Zheng Shu-Li You 《Chemical science》2015,6(7):4179-4183
An organocatalytic asymmetric chlorinative dearomatization of naphthols was realized for the first time, providing chiral naphthalenones with a Cl-containing all-substituted stereocenter in excellent yields and enantioselectivity (up to 97% yield and 96% ee). The reaction features mild reaction conditions, good tolerance of diverse functional groups and simple reaction operation. 相似文献
30.