全文获取类型
收费全文 | 102470篇 |
免费 | 1650篇 |
国内免费 | 1827篇 |
专业分类
化学 | 43415篇 |
晶体学 | 998篇 |
力学 | 7228篇 |
综合类 | 11篇 |
数学 | 34877篇 |
物理学 | 19418篇 |
出版年
2023年 | 200篇 |
2022年 | 430篇 |
2021年 | 538篇 |
2020年 | 466篇 |
2019年 | 487篇 |
2018年 | 10706篇 |
2017年 | 10516篇 |
2016年 | 6905篇 |
2015年 | 1609篇 |
2014年 | 1140篇 |
2013年 | 2073篇 |
2012年 | 5645篇 |
2011年 | 12458篇 |
2010年 | 6698篇 |
2009年 | 7285篇 |
2008年 | 8077篇 |
2007年 | 10191篇 |
2006年 | 1546篇 |
2005年 | 2634篇 |
2004年 | 3019篇 |
2003年 | 3093篇 |
2002年 | 2072篇 |
2001年 | 825篇 |
2000年 | 786篇 |
1999年 | 520篇 |
1998年 | 505篇 |
1997年 | 418篇 |
1996年 | 492篇 |
1995年 | 350篇 |
1994年 | 278篇 |
1993年 | 329篇 |
1992年 | 246篇 |
1991年 | 212篇 |
1990年 | 186篇 |
1989年 | 173篇 |
1988年 | 152篇 |
1987年 | 153篇 |
1986年 | 146篇 |
1985年 | 194篇 |
1984年 | 186篇 |
1983年 | 140篇 |
1982年 | 130篇 |
1981年 | 121篇 |
1980年 | 130篇 |
1979年 | 88篇 |
1978年 | 90篇 |
1977年 | 85篇 |
1976年 | 58篇 |
1975年 | 64篇 |
1974年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Dr. Joaquim Torra Dr. Felipe Viela Dr. Diego Megías Dr. Begoña Sot Prof. Cristina Flors 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(19):e202200026
CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo. 相似文献
2.
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
3.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
4.
5.
6.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
7.
8.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
9.
10.
Dr. Antonio M. Rodríguez Dr. Pilar Prieto Prof. Antonio de la Hoz Prof. Ángel Díaz-Ortiz D. Raúl Martín Prof. José I. García 《ChemistryOpen》2015,4(3):308-317
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. 相似文献