全文获取类型
收费全文 | 183篇 |
免费 | 8篇 |
国内免费 | 4篇 |
专业分类
化学 | 134篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 12篇 |
物理学 | 32篇 |
出版年
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 7篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 22篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1966年 | 3篇 |
1962年 | 1篇 |
排序方式: 共有195条查询结果,搜索用时 31 毫秒
91.
Stefano C. G. Biagini Vernon C. Gibson Matthew R. Giles Edward L. Marshall Michael North 《Journal of polymer science. Part A, Polymer chemistry》2008,46(24):7985-7995
The block and random copolymerization of a series of amino acid and amino ester functionalized norbornenes by ring‐opening metathesis polymerization (ROMP) induced by the well‐defined molybdenum [Mo(?N‐2,6‐iPr? C6H3)(?CHCMe2)Ph)(OCMe3)2] or ruthenium [Ru(PCy)2Cl2(?CHPh)] based initiators is described. The monomers are derived from the amino acids glycine, alanine, and isoleucine or the methyl esters of these amino acids and either endo‐ or exo‐norborn‐5‐ene‐2,3‐dicarboxylic anhydride. Enantiomerically pure monomers afforded optically active polymers, and the mechanism and kinetics of the copolymerizations are investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7985–7995, 2008 相似文献
92.
93.
Michael North 《Angewandte Chemie (International ed. in English)》2009,48(23):4104-4105
Hidden talent : Often perceived to be too thermodynamically and kinetically inert to be a useful chemical feedstock, carbon dioxide adds to allenes under exceptionally mild reductive conditions in the presence of a palladium pincer complex to give β,γ‐unsaturated carboxylic acids (see scheme). This transformation is discussed in the context of the requirements for CO2 fixation. DMF=N,N‐dimethylformamide, Tf=trifluoromethanesulfonyl.
94.
The mechanism by which four Lewis bases, triethylamine, tetrabutylammonium thiocyanate, tetrabutylammonium azide and tetrabutylammonium cyanide, catalyse the addition of trimethylsilyl cyanide to aldehydes is studied by a combination of kinetic and spectroscopic methods. The reactions can exhibit first or second order kinetics corresponding to three different reaction mechanisms. Spectroscopic evidence for the formation of hypervalent silicon species is obtained for reaction between all of the tetrabutylammonium salts and trimethylsilyl cyanide. The reactions are accelerated by the presence of water in the reaction mixture, an effect which is due to a change in the reaction mechanism from Lewis to Br?nsted base catalysis. Tetrabutylammonium thiocyanate is shown to be an excellent catalyst for the synthesis of cyanohydrin trimethylsilyl ethers on a preparative scale. 相似文献
95.
Success in isoelectric trapping separations critically depends on the knowledge of the accurate operational pH value of the buffering membranes used. Currently, due to a lack of easy, rapid, accurate methods that can be used for the post-synthesis determination of the operational pH value of a buffering membrane, only nominal pH values calculated from the amounts of the reagents used in the synthesis of the membranes and their acid-base dissociation constants are available. To rectify this problem, UV-absorbing and fluorescent carrier ampholyte mixtures were prepared by alkylating pentaethylenehexamine with a chromophore and a fluorophore, followed by Michael addition of acrylic acid and itaconic acid to the resulting oligoamine. Carrier ampholyte mixtures, with evenly distributed absorbance values across the 3相似文献
96.
97.
Michael J. North 《Computational & Mathematical Organization Theory》2001,7(4):331-337
Complex Adaptive Systems (CAS) can be applied to investigate large-scale socio-cognitive-technical systems. Viewing such systems from a multi-agent social and organizational perspective allows innovative computational policy analysis. Argonne National Laboratory (ANL) has taken such a perspective to produce an integrated model of the electric power and natural gas markets. This model focuses on the organizational interdependencies between these markets. These organizational interdependencies are being strained by fundamental market transformations. 相似文献
98.
Anton Deitmar School of Mathematical Sciences University of Exeter Laver Building North Park Road Exeter EX QE Devon UK 《数学物理学报(B辑英文版)》2001,(1)
0 IntroductionThe group of norm-1 ideles A1 over a global field lt acts by 1111lltip1ication on t11e additivegroup of adeIes A. Let G = A1 be A be tl1eir semidirect product. Let r be its arithnletic sub-group kx oc k. For the case k = Q Dorian Goldfeld gavc ill [2] a Schwartz kernel on r\G whosegeometrical trace equals the prime 11un1ber side of the explicit fOr1llulas of A. Weil. A spectralillterpretatiou in the seuse of the Selberg trace formula is cal1ed for. In order that a geolllet… 相似文献
99.
100.
SU XinMing ZHANG JunHui WANG Jing BI YanQiang QIE DianFu XIANG ZhiHai XUE MingDe 《中国科学:物理学 力学 天文学(英文版)》2015,(4):63-71
Thermally induced vibration(TIV)is a typical failure of large-scale space structures.This paper reports a laboratory experiment that aims to investigate this unusual structural behavior of complex engineering structures.With the help of a Fourier finite element program,the fixing of a space boom section is well designed so that the TIV can be successfully observed.Although the observed torsional vibration mode is different from the bending vibration mode predicted by the classic theory based on a simple beam model,it can be successfully explained by the general thermal structural interaction theory.This demonstrates the validity of the theoretical model and the necessity of using finite element program to analyze complex engineering structures. 相似文献