全文获取类型
收费全文 | 18704篇 |
免费 | 3254篇 |
国内免费 | 2211篇 |
专业分类
化学 | 13576篇 |
晶体学 | 280篇 |
力学 | 1110篇 |
综合类 | 147篇 |
数学 | 1994篇 |
物理学 | 7062篇 |
出版年
2024年 | 53篇 |
2023年 | 406篇 |
2022年 | 521篇 |
2021年 | 656篇 |
2020年 | 728篇 |
2019年 | 785篇 |
2018年 | 643篇 |
2017年 | 596篇 |
2016年 | 895篇 |
2015年 | 880篇 |
2014年 | 1101篇 |
2013年 | 1484篇 |
2012年 | 1759篇 |
2011年 | 1904篇 |
2010年 | 1278篇 |
2009年 | 1218篇 |
2008年 | 1241篇 |
2007年 | 1204篇 |
2006年 | 999篇 |
2005年 | 852篇 |
2004年 | 703篇 |
2003年 | 544篇 |
2002年 | 491篇 |
2001年 | 418篇 |
2000年 | 409篇 |
1999年 | 320篇 |
1998年 | 276篇 |
1997年 | 220篇 |
1996年 | 240篇 |
1995年 | 199篇 |
1994年 | 182篇 |
1993年 | 157篇 |
1992年 | 154篇 |
1991年 | 115篇 |
1990年 | 107篇 |
1989年 | 92篇 |
1988年 | 54篇 |
1987年 | 47篇 |
1986年 | 48篇 |
1985年 | 50篇 |
1984年 | 30篇 |
1983年 | 22篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
962.
963.
Pengfei Xu Dr. Liang Gao Prof. Dr. Chunhua Cai Prof. Dr. Jiaping Lin Dr. Liquan Wang Prof. Dr. Xiaohui Tian 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(34):14387-14391
Toroids and helices are fundamental geometrical structures in nature. Polymers can self-assemble into various nanostructures, including both toroids and helices; however, nanostructures combining toroidal and helical morphologies (that is, helical toroids) are rarely observed. A binary system is reported containing polypeptide homopolymer and its block copolymer, which can hierarchically self-assemble into uniform helical nanotoroids in solution. The formation of the helical toroids is a successive two-step process. First, the homopolymers aggregate into fibrils and convolve into toroids, thereby resembling the toroidal condensation of deoxyribonucleic acid (DNA) chains. Second, the block copolymers self-assemble on the homopolymer toroids and result in helical surface patterns. Additionally, the chirality of the surface helical patterns can be varied by the chirality of the polypeptide block copolymers. 相似文献
964.
Yu-Rong Chen Dr. Annavareddi Naresh Dr. Suh-Yuen Liang Dr. Chun-Hung Lin Dr. Rong-Jie Chein Dr. Hsiao-Ching Lin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13639-13643
The 1,3-enyne moiety is commonly found in cyclohexanoid natural products produced by endophytic and plant pathogenic fungi. Asperpentyn ( 1 ) is a 1,3-enyne-containing cyclohexanoid terpenoid isolated from Aspergillus and Pestalotiopsis. The genetic basis and biochemical mechanism of 1,3-enyne biosynthesis in 1 , and other natural products containing this motif, has remained enigmatic despite their potential ecological roles. Identified here is the biosynthetic gene cluster and characterization of two crucial enzymes in the biosynthesis of 1 . A P450 monooxygenase that has a dual function, to first catalyze dehydrogenation of the prenyl chain to generate a cis-diene intermediate and then serve as an acetylenase to yield an alkyne moiety, and thus the 1,3-enyne, was discovered. A UbiA prenyltransferase was also characterized and it is unusual in that it favors transferring a five-carbon prenyl chain, rather than a polyprenyl chain, to a p-hydroxybenzoic acid acceptor. 相似文献
965.
Rational Design of Cyclometalated Iridium(III) Complexes for Three-Photon Phosphorescence Bioimaging
Dr. Chengzhi Jin Fengyin Liang Dr. Jinquan Wang Dr. Lili Wang Dr. Jiangping Liu Xinxing Liao Dr. Thomas W. Rees Bo Yuan Prof. Dr. Hui Wang Prof. Dr. Yong Shen Prof. Dr. Zhong Pei Prof. Dr. Liangnian Ji Prof. Dr. Hui Chao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16121-16125
Compared to 2PE (two-photon excitation) microscopy, 3PE microscopy has superior spatial resolution, deeper tissue penetration, and less defocused interference. The design of suitable agents with a large Stokes shift, good three-photon absorption (3PA), subcellular targeting, and fluorescence lifetime imaging (FLIM) properties, is challenging. Now, two IrIII complexes (3PAIr1 and 3PAIr2) were developed as efficient three-photon phosphorescence (3PP) agents. Calculations reveal that the introduction of a new group to the molecular scaffold confers a quadruple promotion in three-photon transition probability. Confocal and lifetime imaging of mitochondria using IrIII complexes as 3PP agents is shown. The complexes exhibit low working concentration (50 nm ), fast uptake (5 min), and low threshold for three-photon excitation power (0.5 mW at 980 nm). The impressive tissue penetration depth (ca. 450 μm) allowed the 3D imaging and reconstruction of brain vasculature from a living specimen. 相似文献
966.
Guoyu Zhang Song Zhou Dr. Liang Fu Dr. Pinhong Chen Prof. Yibiao Li Prof. Dr. Jianping Zou Prof. Dr. Guosheng Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20619-20624
The first copper-catalyzed asymmetric cyanation and etherification reactions of enamides have been established, where a carbon-centered radical adjacent to a nitrogen atom (CRAN) is enantioselectively trapped by a chiral copper(II) species. Moreover, the asymmetric cyanation of vinyl esters was disclosed as well. These reactions feature very mild reaction conditions and high functional group tolerance, and give a series of chiral α-cyano amides, α-cyano esters and α-hemiaminals in good yields with excellent enantioselectivity. The chiral α-cyano amides can be easily converted into enantioenriched 1,2-diamines and amino acids. 相似文献
967.
Yi-Fan Wang Yiyu Liang Yan-Fang Wu Jian Yang Xu Zhang Dr. Dandan Cai Dr. Xu Peng Dr. Mohamedally Kurmoo Prof. Dr. Ming-Hua Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13334-13339
The in situ tracking of the pyrolysis of a binary molecular cluster [Zn7(μ3-CH3O)6(L)6][ZnLCl2]2 is presented with one brucite disk and two mononuclear fragments (L=mmimp: 2-methoxy-6-((methylimino)-methyl)phenolate) to porous carbon using TG-MS from 30 to 900 °C. Following up the spilled gas product during the decomposed reaction of zinc cluster along the temperature rising, and in conjunction with XRD, SEM, BET and other materials characterization, where three key steps were observed: 1) cleavage of the bulky external ligand; 2) reduction of ZnO and 3) volatilization of Zn. The real-time-dependent phase-sequential evolution of the remaining products and the processing of pore forming template transformation are proposed simultaneously. The porous carbon structure featuring a uniform nano-sized pore distribution synthesized at 900 °C with the highest surface area of 1644 m2 g−1 and pore volume of 0.926 cm3 g−1 exhibits the best known capacitance of 662 F g−1 at 0.5 A g−1. 相似文献
968.
Qunfeng Fu Dr. Hongyu Li Dongban Duan Changlun Wang Siyong Shen Prof. Dr. Huimin Ma Prof. Dr. Zhibo Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21730-21736
Radiation-induced cleavage for controlled release in vivo is yet to be established. We demonstrate the use of 3,5-dihydroxybenzyl carbamate (DHBC) as a masking group that is selectively and efficiently removed by external radiation in vitro and in vivo. DHBC reacts mainly with hydroxyl radicals produced by radiation to afford hydroxylation at para/ortho positions, followed by 1,4- or 1,6-elimination to rescue the functionality of the client molecule. The reaction is rapid and can liberate functional molecules under physiological conditions. This controlled-release platform is compatible with living systems, as demonstrated by the release of a rhodol fluorophore derivative in cells and tumor xenografts. The combined benefits of the robust caging group, the good release yield, and the independence of penetration depth make DHBC derivatives attractive chemical caging moieties for use in chemical biology and prodrug activation. 相似文献
969.
Yajie Liu Zelin Duan Jing Fang Fan Zhang Prof. Junyu Xiao Prof. Wen-Bin Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16256-16261
Herein, we report the biosynthesis of protein heterocatenanes using a programmed sequence of multiple post-translational processing events including intramolecular chain entanglement, in situ backbone cleavage, and spontaneous cyclization. The approach is general, autonomous, and can obviate the need for any additional enzymes. The catenane topology was convincingly proven using a combination of SDS-PAGE, LC-MS, size exclusion chromatography, controlled proteolytic digestion, and protein crystallography. The X-ray crystal structure clearly shows two mechanically interlocked protein rings with intact folded domains. It opens new avenues in the nascent field of protein-topology engineering. 相似文献
970.
Dr. Qingwei Zhou Prof. Jialong Duan Prof. Xiya Yang Dr. Yanyan Duan Prof. Qunwei Tang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22181-22185
Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr3 perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS2/CsPbBr3 van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond-free surface to act as a lubricant between ETL and CsPbBr3 perovskite. Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days. 相似文献