全文获取类型
收费全文 | 194篇 |
免费 | 1篇 |
专业分类
化学 | 99篇 |
力学 | 5篇 |
数学 | 5篇 |
物理学 | 86篇 |
出版年
2020年 | 3篇 |
2014年 | 1篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 8篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1942年 | 2篇 |
1939年 | 3篇 |
1936年 | 2篇 |
1935年 | 1篇 |
1933年 | 2篇 |
1931年 | 1篇 |
1924年 | 2篇 |
1919年 | 1篇 |
1904年 | 1篇 |
排序方式: 共有195条查询结果,搜索用时 0 毫秒
131.
132.
133.
134.
135.
136.
Lee J. Higham Ann J. Middleton Katie Heslop Paul G. Pringle Angharad Barber A. Guy Orpen 《Journal of organometallic chemistry》2004,689(19):2963-2968
The indan derived diphosphine, cis-1,3-(diphenylphosphino)indan (anphos) is synthesised by the addition of Ph2P(BH3)Li to cis-1,3-dibromoindan followed by deprotection with diethylamine. Anphos readily forms the bicyclic chelates [RhCl(CO)(anphos)], [PtCl2(anphos)], [PtCl(Me)(anphos)] and [FeCl2(anphos)]. The crystal structures of [FeCl2(anphos)] and the monoxide complex, [RhCl(CO)(anphosO)] have been determined. Reaction of the diphosphine with [Rh(acac)(CO)2] under moderate hydroformylation conditions catalysed the formation of 1-heptanal and branched aldehydes from 1-hexene in a ratio of 1.5:1. 相似文献
137.
[reaction: see text] A new and general four-step synthesis of protected alpha-substituted and alpha,alpha-disubstituted amino acids has been developed. The key step involves intramolecular ammonium ylide generation from a copper carbenoid with concomitant [2,3] rearrangement. The aromatic template serves as a tether, protecting group, and activating group for peptide coupling. The ylide rearrangement products can be converted into protected cyclic amino acids by ring-closing metathesis. 相似文献
138.
Bogorad P. Behr J. Brash E. J Cates G. D. Cummings W. J. Gorelov A. Hasinoff M. D. Hausser O. Hicks K. Holmes R. Huang J. C. Kumar K. S. Larson B. Lorentzon W. McCracken J. Middleton H. Michaux P. Saettler E. Siegel D. Souder P. A. Swenson D. R. Tupa D. Wang X. Young A. 《Hyperfine Interactions》1996,101(1):433-437
We describe the first measurement of the spin dependence of the reaction: µ–+3He3H+µ. This spin dependence is quite sensitive to the induced pseudoscalar form factor,F
P, a piece of the weak charged nuclear current of3He about which, experimentally, relatively little is known. The data are presently being analyzed and we plan to quote a number forF
P shortly. 相似文献
139.
Methods for determining how a drug interacts with cellular membranes at the molecular level can give valuable insight into the mode of action of the drug and its absorption, distribution and metabolism profile. A procedure is described here to determine the orientation and location of the lipophilic drug trifluoperazine (TFP) intercalated into dimyristoylphosphatidylcholine (DMPC) bilayers, by using a novel combination of high-resolution solid-state nuclear magnetic resonance (SSNMR) methods to observe signals from (13)C within the drug at natural abundance. SSNMR measurements of (1)H-(13)C dipolar couplings for TFP and selective broadening of (13)C NMR peaks by paramagnetic Mn(2+) together suggest a model for the location, orientation and dynamics of the drug within lipid bilayers that offers an explanation for the lysoprotective effect of the drug at low concentrations. The experiments described are straightforward to implement and can be used for the routine analysis of drug-membrane interactions to provide useful information for drug design and structure refinement. 相似文献
140.
Errington RJ Petkar SS Middleton PS McFarlane W Clegg W Coxall RA Harrington RW 《Journal of the American Chemical Society》2007,129(40):12181-12196
The methoxo-bridged, dimeric, ZrIV-substituted Lindqvist-type polyoxometalate (POM) (nBu4N)6[{(mu-MeO)ZrW5O18}2], (TBA)61, has been synthesized by stoichiometric hydrolysis of Zr(OnPr)4, [{Zr(OiPr)3(mu-OnPr)(iPrOH)}2], or [{Zr(OiPr)4(iPrOH)}2] and [{WO(OMe)4}2] in the presence of (nBu4N)2WO4, providing access to the systematic nonaqueous chemistry of ZrW5 POMs for the first time and an efficient route to 17O-enriched samples for 17O NMR studies. 1H NMR provided no evidence for dissociation of 1 in solution, although exchange with MeOH was shown to be slow by an EXSY study. Reactions with HX at elevated temperatures gave a range of anions [{XZrW5O18}n]3n- (X = OH, 3; OPh, 4; OC6H4Me-4, 5; OC6H4(CHO)-2, 6; acac, 7; OAc, 8), where n = 2 for 3 and n = 1 for 4-8, while 1H and 17O NMR studies of hydrolysis of 1 revealed the formation of an intermediate [(mu-MeO)(mu-HO)(ZrW5O18)2]6-. Electrospray ionization mass spectrometry of 1 and 3 illustrated the robust nature of the ZrW5O18 framework, and X-ray crystal structure determinations showed that steric interactions between ligands X and the ZrW5O18 surface are important. The coordination number of Zr is restricted to six in aryloxides 4 and 5, while seven-coordination is achieved in the chelate complexes 6-8. Given the inert nature of the methoxo bridges in 1, protonation of ZrOW sites is proposed as a possible step in reactions with HX. The diphenylphosphinate ligand in [(Ph2PO2)ZrW5O18]3- was found to be labile and upon attempted recrystallization the aggregate [(mu3-HO)2(ZrW5O18)3H]7- 9 was formed, which was found to be protonated at ZrOZr and ZrOW sites. This work demonstrates the flexibility of the {ZrW5O18}2- core as a molecular platform for modeling catalysis by tungstated zirconia surfaces. 相似文献