全文获取类型
收费全文 | 3049篇 |
免费 | 162篇 |
国内免费 | 13篇 |
专业分类
化学 | 2250篇 |
晶体学 | 11篇 |
力学 | 143篇 |
数学 | 388篇 |
物理学 | 432篇 |
出版年
2023年 | 31篇 |
2022年 | 59篇 |
2021年 | 59篇 |
2020年 | 67篇 |
2019年 | 67篇 |
2018年 | 43篇 |
2017年 | 41篇 |
2016年 | 95篇 |
2015年 | 86篇 |
2014年 | 105篇 |
2013年 | 156篇 |
2012年 | 222篇 |
2011年 | 267篇 |
2010年 | 132篇 |
2009年 | 147篇 |
2008年 | 225篇 |
2007年 | 206篇 |
2006年 | 216篇 |
2005年 | 206篇 |
2004年 | 183篇 |
2003年 | 143篇 |
2002年 | 126篇 |
2001年 | 53篇 |
2000年 | 33篇 |
1999年 | 22篇 |
1998年 | 23篇 |
1997年 | 23篇 |
1996年 | 26篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 4篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 8篇 |
1971年 | 5篇 |
1970年 | 5篇 |
排序方式: 共有3224条查询结果,搜索用时 15 毫秒
991.
Cline Taglang Luis Miguel Martínez‐Prieto Iker delRosal Laurent Maron Romuald Poteau Karine Philippot Bruno Chaudret Serge Perato Anaïs SamLone Cline Puente Christophe Dugave Bernard Rousseau Grgory Pieters 《Angewandte Chemie (International ed. in English)》2015,54(36):10474-10477
The activation of C H bonds has revolutionized modern synthetic chemistry. However, no general strategy for enantiospecific C H activation has been developed to date. We herein report an enantiospecific C H activation reaction followed by deuterium incorporation at stereogenic centers. Mechanistic studies suggest that the selectivity for the α‐position of the directing heteroatom results from a four‐membered dimetallacycle as the key intermediate. This work paves the way to novel molecular chemistry on nanoparticles. 相似文献
992.
Synthesis of Unprecedented Sulfonylated Phosphono‐exo‐Glycals Designed as Inhibitors of the Three Mycobacterial Galactofuranose Processing Enzymes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Christophe J.‐M. Frédéric Dr. Abdellatif Tikad Jian Fu Dr. Weidong Pan Ruixiang B. Zheng Dr. Akihiko Koizumi Dr. Xiaochao Xue Prof. Todd L. Lowary Prof. Stéphane P. Vincent 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15913-15920
This study reports a new methodology to synthesize exo‐glycals bearing both a sulfone and a phosphonate. This synthetic strategy provides a way to generate exo‐glycals displaying two electron‐withdrawing groups and was applied to eight different carbohydrates from the furanose and pyranose series. The Z/E configurations of these tetrasubstituted enol ethers could be ascertained using NMR spectroscopic techniques. Deprotection of an exo‐glycal followed by an UMP (uridine monophosphate) coupling generated two new UDP (uridine diphosphate)‐galactofuranose analogues. These two Z/E isomers were evaluated as inhibitors of UGM, GlfT1, and GlfT2, the three mycobacterial galactofuranose processing enzymes. Molecule 46‐(E) is the first characterized inhibitor of GlfT1 reported to date and was also found to efficiently inhibit UGM in a reversible manner. Interestingly, GlfT2 showed a better affinity for the (Z) isomer. The three enzymes studied in the present work are not only interesting because, mechanistically, they are still the topic of intense investigations, but also because they constitute very important targets for the development of novel antimycobacterial agents. 相似文献
993.
Mathurin Grogna Rudi Cloots André Luxen Christine Jérôme Catherine Passirani Nolwenn Lautram Jean‐F. Desreux Christophe Detrembleur 《Journal of polymer science. Part A, Polymer chemistry》2011,49(17):3700-3708
New hydrosoluble magnetic resonance imaging (MRI) macrocontrast agents are synthesized by reversible addition fragmentation chain transfer (RAFT) copolymerization of poly(ethylene oxide) methyl ether acrylate (PEOMA) with an acrylamide bearing a ligand for gadolinium, followed by the complexation of Gd3+. This convenient and simple grafting through approach leads to macrocontrast agents with a high relaxivity at high frequency that is imparted by the restricted tumbling of the Gd3+ complex caused by its attachment to the polymer backbone. Importantly a very low protein adsorption is also evidenced by the hemolytic CH50 test. It is the result of the poly(ethylene oxide) (PEO) brush that efficiently hides the gadolinium complex and renders it stealth to the proteins of the immune system. Improved contrast and long blood circulating properties are thus expected for these macrocontrast agents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
994.
Evaluation of a combined glycomics and glycoproteomics approach for studying the major glycoproteins present in biofluids: Application to cerebrospinal fluid
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
995.
Maxime Charman Frédéric Léonardi Sébastien Dominguez Cédric Bissuel Christophe Derail 《Journal of Polymer Science.Polymer Physics》2011,49(22):1597-1604
The dispersion of multiwalled carbon nanotubes (CNTs) in an ethylene propylene rubber matrix was investigated using an internal mixer. Poly(ethylene‐co‐polyvinyl acetate) (EVA) statistic copolymer was used as a dispersing agent. The effects of the concentration of the dispersing agent and the matrix viscosity on the quality of the dispersion of 1 wt % of CNTs were studied by using microscopy and rheology in the melt state. It was demonstrated that the dispersion is governed principally by the viscosity of the matrix. As expected, better dispersion was observed when the matrix exhibited a lower viscosity. The influence of the filler content on the rheological and electrical properties is presented. A Cross model with a yield stress is proposed to describe the rheological behavior of these materials, which exhibit a viscoelastic solid behavior from 1 wt % CNT content. Electrical measurement data indicate that the electrical percolation threshold was 2.9 wt %. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1597–1604, 2011 相似文献
996.
Comprehensive Two-dimensional Gas Chromatography for Analysis of the Volatile Compounds and Fishy Odor Off-flavors from Heated Rapeseed Oil 总被引:1,自引:0,他引:1
997.
998.
Roland Coratger Bastien Calmettes Youness Benjalal Xavier Bouju Christophe Coudret 《Surface science》2012,606(3-4):444-449
The electronic and structural properties of large molecules composed of a central hexa-phenylbenzene core surrounded by six adamantyl groups (Ad6HPB) adsorbed on Ag(111) have been investigated using low temperature scanning tunneling microscopy (STM), adsorption and image calculations. On large 2D domains, the molecular organization displays two lattices. In one of them, molecules are slightly nested as a result of their relative flexibility during packing. These compounds also exhibit contrast variations in terms of used bias voltage in the self-assembled domains as well as in single molecule observations. This is attributed to the peculiar electronic properties of Ad6HPB and to the role of peripheral groups. 相似文献
999.
1000.