全文获取类型
收费全文 | 70859篇 |
免费 | 16133篇 |
国内免费 | 299篇 |
专业分类
化学 | 73406篇 |
晶体学 | 241篇 |
力学 | 1842篇 |
数学 | 6505篇 |
物理学 | 5297篇 |
出版年
2024年 | 433篇 |
2023年 | 4342篇 |
2022年 | 1643篇 |
2021年 | 2749篇 |
2020年 | 5040篇 |
2019年 | 2617篇 |
2018年 | 2663篇 |
2017年 | 944篇 |
2016年 | 6167篇 |
2015年 | 6033篇 |
2014年 | 5528篇 |
2013年 | 6579篇 |
2012年 | 4785篇 |
2011年 | 3250篇 |
2010年 | 4324篇 |
2009年 | 4116篇 |
2008年 | 2933篇 |
2007年 | 2643篇 |
2006年 | 2073篇 |
2005年 | 1903篇 |
2004年 | 1620篇 |
2003年 | 1416篇 |
2002年 | 1294篇 |
2001年 | 425篇 |
2000年 | 402篇 |
1999年 | 371篇 |
1998年 | 346篇 |
1997年 | 397篇 |
1996年 | 529篇 |
1995年 | 450篇 |
1994年 | 364篇 |
1993年 | 452篇 |
1992年 | 331篇 |
1991年 | 292篇 |
1988年 | 307篇 |
1987年 | 258篇 |
1985年 | 393篇 |
1984年 | 396篇 |
1983年 | 306篇 |
1982年 | 384篇 |
1981年 | 407篇 |
1980年 | 401篇 |
1979年 | 375篇 |
1978年 | 352篇 |
1977年 | 389篇 |
1976年 | 387篇 |
1975年 | 393篇 |
1974年 | 404篇 |
1973年 | 317篇 |
1970年 | 254篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
Xudong Li Yuansong Wei Yuchen Wu Prof. Dr. Lichen Yin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22733-22742
The success of intracellular protein therapy demands efficient delivery and selective protein activity in diseased cells. Therefore, a cascaded nanozymogen consisting of a hypoxia-activatable pro-protein, a hypoxia-inducing protein, and a hypoxia-strengthened intracellular protein delivery nanovehicle was developed. RPAB, an enzymatically inactive pro-protein of RNase, reversibly caged with hypoxia-cleavable azobenzene, was delivered with glucose oxidase (GOx) using hypoxia-responsive nanocomplexes (NCs) consisting of azobenzene-cross-linked oligoethylenimine (AOEI) and hyaluronic acid (HA). Upon NC-mediated delivery into cancer cells, GOx catalyzed glucose decomposition and aggravated tumoral hypoxia, which drove the recovery of RPAB back to the hydrolytically active RNase and expedited the degradation of AOEI to release more protein cargoes. Thus, the catalytic reaction of the nanozymogen was self-accelerated and self-cycled, ultimately leading to a cooperative anti-cancer effect between GOx-mediated starvation therapy and RNase-mediated pro-apoptotic therapy. 相似文献
922.
923.
924.
Dr. Yuan Liu Dr. Jin-Cheng Liu Teng-Hao Li Zeng-Hui Duan Dr. Tian-Yu Zhang Ming Yan Dr. Wan-Lu Li Prof. Dr. Hai Xiao Prof. Dr. Yang-Gang Wang Prof. Dr. Chun-Ran Chang Prof. Dr. Jun Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18745-18749
The direct, nonoxidative conversion of methane on a silica-confined single-atom iron catalyst is a landmark discovery in catalysis, but the proposed gas-phase reaction mechanism is still open to discussion. Here, we report a surface reaction mechanism by computational modeling and simulations. The activation of methane occurs at the single iron site, whereas the dissociated methyl disfavors desorption into gas phase under the reactive conditions. In contrast, the dissociated methyl prefers transferring to adjacent carbon sites of the active center (Fe1©SiC2), followed by C−C coupling and hydrogen transfer to produce the main product (ethylene) via a key −CH−CH2 intermediate. We find a quasi Mars–van Krevelen (quasi-MvK) surface reaction mechanism involving extracting and refilling the surface carbon atoms for the nonoxidative conversion of methane on Fe1©SiO2 and this surface process is identified to be more plausible than the alternative gas-phase reaction mechanism. 相似文献
925.
Dr. Wan-Shan Li Dr. Ren-Jie Yan Yi Yu Prof. Zhi Shi Dr. Attila Mándi Dr. Li Shen Prof. Tibor Kurtán Prof. Jun Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):13128-13136
Marine dinoflagellates produce remarkable organic molecules, particularly those with polyoxygenated long-carbon-chain backbones, namely super-carbon-chain compounds (SCCCs), characterized by the presence of numerous stereogenic carbon centers on acyclic polyol carbon chains. Even today, it is a challenge to determine the absolute configurations of these compounds. In this work, the planar structures and absolute configurations of two highly flexible SCCCs, featuring either a C69- or C71-linear carbon backbone, gibbosols A and B, respectively, each containing thirty-seven stereogenic carbon centers, were unambiguously established by a combined chemical, spectroscopic, and computational approach. The discovery of gibbosols A and B with two hydrophilic acyclic polyol chains represents an unprecedented class of SCCCs. A reasonable convergent strategy for the biosynthesis of these SCCCs was proposed. 相似文献
926.
Elaine Tsui Anthony J. Metrano Yuto Tsuchiya Prof. Robert R. Knowles 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):11943-11947
We report a catalytic, light-driven method for the intramolecular hydroetherification of unactivated alkenols to furnish cyclic ether products. These reactions occur under visible-light irradiation in the presence of an IrIII-based photoredox catalyst, a Brønsted base catalyst, and a hydrogen-atom transfer (HAT) co-catalyst. Reactive alkoxy radicals are proposed as key intermediates, generated by direct homolytic activation of alcohol O−H bonds through a proton-coupled electron-transfer mechanism. This method exhibits a broad substrate scope and high functional-group tolerance, and it accommodates a diverse range of alkene substitution patterns. Results demonstrating the extension of this catalytic system to carboetherification reactions are also presented. 相似文献
927.
Sebastian Spicher Prof. Stefan Grimme 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15795-15803
Modern chemistry seems to be unlimited in molecular size and elemental composition. Metal-organic frameworks or biological macromolecules involve complex architectures and a large variety of elements. Yet, a general and broadly applicable theoretical method to describe the structures and interactions of molecules beyond the 1000-atom size regime semi-quantitatively is not self-evident. For this purpose, a generic force field named GFN-FF is presented, which is completely newly developed to enable fast structure optimizations and molecular-dynamics simulations for basically any chemical structure consisting of elements up to radon. The freely available computer program requires only starting coordinates and elemental composition as input from which, fully automatically, all potential-energy terms are constructed. GFN-FF outperforms other force fields in terms of generality and accuracy, approaching the performance of much more elaborate quantum-mechanical methods in many cases. 相似文献
928.
929.
De-Hui Guan Xiao-Xue Wang Ma-Lin Li Fei Li Li-Jun Zheng Prof. Xiao-Lei Huang Prof. Ji-Jing Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19686-19692
A photoinduced flexible Li-CO2 battery with well-designed, hierarchical porous, and free-standing In2S3@CNT/SS (ICS) as a bifunctional photoelectrode to accelerate both the CO2 reduction and evolution reactions (CDRR and CDER) is presented. The photoinduced Li-CO2 battery achieved a record-high discharge voltage of 3.14 V, surpassing the thermodynamic limit of 2.80 V, and an ultra-low charge voltage of 3.20 V, achieving a round trip efficiency of 98.1 %, which is the highest value ever reported (<80 %) so far. These excellent properties can be ascribed to the hierarchical porous and free-standing structure of ICS, as well as the key role of photogenerated electrons and holes during discharging and charging processes. A mechanism is proposed for pre-activating CO2 by reducing In3+ to In+ under light illumination. The mechanism of the bifunctional light-assisted process provides insight into photoinduced Li-CO2 batteries and contributes to resolving the major setbacks of the system. 相似文献
930.