全文获取类型
收费全文 | 35976篇 |
免费 | 4953篇 |
国内免费 | 3487篇 |
专业分类
化学 | 19364篇 |
晶体学 | 722篇 |
力学 | 3348篇 |
综合类 | 201篇 |
数学 | 3554篇 |
物理学 | 17227篇 |
出版年
2024年 | 99篇 |
2023年 | 373篇 |
2022年 | 1006篇 |
2021年 | 1079篇 |
2020年 | 1287篇 |
2019年 | 1195篇 |
2018年 | 1074篇 |
2017年 | 1291篇 |
2016年 | 1715篇 |
2015年 | 1473篇 |
2014年 | 1925篇 |
2013年 | 3395篇 |
2012年 | 2247篇 |
2011年 | 2527篇 |
2010年 | 2020篇 |
2009年 | 2420篇 |
2008年 | 2310篇 |
2007年 | 2411篇 |
2006年 | 2057篇 |
2005年 | 1664篇 |
2004年 | 1442篇 |
2003年 | 1297篇 |
2002年 | 1398篇 |
2001年 | 948篇 |
2000年 | 870篇 |
1999年 | 782篇 |
1998年 | 707篇 |
1997年 | 504篇 |
1996年 | 422篇 |
1995年 | 359篇 |
1994年 | 365篇 |
1993年 | 247篇 |
1992年 | 237篇 |
1991年 | 163篇 |
1990年 | 127篇 |
1989年 | 115篇 |
1988年 | 121篇 |
1987年 | 110篇 |
1986年 | 91篇 |
1985年 | 92篇 |
1984年 | 79篇 |
1983年 | 44篇 |
1982年 | 70篇 |
1981年 | 44篇 |
1980年 | 23篇 |
1979年 | 43篇 |
1978年 | 31篇 |
1977年 | 24篇 |
1976年 | 24篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Dr. Yolimar Gil Dr. Alejandro Castro-Alvarez Dr. Pablo Fuentealba Prof. Evgenia Spodine Dr. Daniel Aravena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202200336
Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands. A natural approach for axial-equatorial control is the employment of macrocycles acting in a belt conformation, providing the equatorial coordination environment, and leaving room for axial ligands. In this review, we present a survey of SMMs based on the macrocycle belt motif. Literature systems are divided in three families (crown ether, Schiff-base and metallacrown) and their general properties in terms of structural stability and SMM performance are briefly discussed. 相似文献
3.
This paper infers from a generalized Picone identity the uniqueness of the stable positive solution for a class of semilinear equations of superlinear indefinite type, as well as the uniqueness and global attractivity of the coexistence state in two generalized diffusive prototypes of the symbiotic and competing species models of Lotka–Volterra. The optimality of these uniqueness theorems reveals the tremendous strength of the Picone identity. 相似文献
4.
5.
Tapasi Chand Laxmikanta Khamari Deepak Chopra Saptarshi Mukherjee Manmohan Kapur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202200723
A one-step Rh-catalyzed site-selective ortho-C−H alkynylation of perylene as well as naphthalene mono- and diimides is reported. A single step regioselective access to ortho-C−H alkynylated derivatives of these ryleneimides not only increases the step economy of the ortho-functionalization on these dyes but also provides a quick access route towards highly functionalized dyes that have potential optoelectronic applications. Increased solubility of tetra(triisopropylsilyl)acetylenyl PDIs in organic solvents greatly enhances their utility for further derivatization. 相似文献
6.
7.
8.
9.
10.
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