全文获取类型
收费全文 | 155篇 |
免费 | 3篇 |
学科分类
数理化 | 158篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 11篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1967年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有158条查询结果,搜索用时 843 毫秒
81.
Hydrothermal synthesis has afforded [Co3(oba)3(bpmp)2]n [oba = oxybis(benzoate), bpmp = bis(4-pyridylmethyl)piperazine], a chiral coordination polymer possessing an aesthetic self-catenated three-dimensional structure with an unprecedented 8-connected uninodal 4(4)5(17)6(7) topology. The network is formed by the junction of {Co3O2} clusters into three different homochiral interlocked helical motifs, linked by one type of "infinite" chain pattern. Antiferromagnetic exchange is observed within the {Co3O2} clusters. 相似文献
82.
Li X Burrell CE Staples RJ Borhan B 《Journal of the American Chemical Society》2012,134(22):9026-9029
The absolute configurations of 1,n-glycols (n = 2-12, 16) bearing two chiral centers were rapidly determined via exciton-coupled circular dichroism (ECCD) using a tris(pentafluorophenyl)porphyrin (TPFP porphyrin) tweezer system in a nonempirical fashion devoid of chemical derivatization. A unique "side-on" approach of the porphyrin tweezer relative to the diol guest molecule is suggested as the mode of complexation. 相似文献
83.
Penfold J Staples E Tucker I Carroll P Clayton I Cowan JS Lawton G Amin S Ferrante A Ruddock N 《The journal of physical chemistry. B》2006,110(2):1073-1082
We have used small angle neutron scattering, SANS, to investigate the elongational flow induced ordering in surfactant micelles and mesophases. Spatially resolved SANS measurements have been used to determine the distribution of orientational ordering over the flow velocity pattern in an elongational flow cell, and comparison with the effects of shear flow are made. Two different surfactant systems have been studied, the charged wormlike mixed micelles of hexaethylene monododecyl ether, C16E6/hexadecyl trimethylammonium bromide, C16TAB (3% C16E(6)/5 mol% C16TAB), and the Lalpha lamellar phase of C16E6 (50.6 wt% C16E6 at 55 degrees C), and a substantially different response is observed. The orientational distribution of the Lalpha lamellar phase of C16E6 reflects the flow velocity pattern distribution within the cell, whereas for the wormlike mixed micelles of C16E6/C16TAB this is not the case, and this is associated with the shear thinning behavior of that system. 相似文献
84.
Transonic trailing-edge flow 总被引:1,自引:0,他引:1
Bodonyi RJ; Kluwick A 《The Quarterly Journal of Mechanics and Applied Mathematics》1998,51(2):297-310
85.
86.
Tasker SZ Brandsen BM Ryu KA Snapper GS Staples RJ DeKock RL Anderson CE 《Organic letters》2011,13(23):6224-6227
A new method for the synthesis of β-iodo N-alkenyl 2-pyridones from substituted 2-propargyloxypyridines has been discovered . These compounds present a unique complement of orthogonal functionality and structural characteristics that are unavailable via other routes. The ready access to these compounds renders them an important entry point for the preparation of more complex N-alkyl pyridone-containing targets. 相似文献
87.
Hadi Gholami Aman Kulshrestha Olivia K. Favor Richard J. Staples Babak Borhan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10216-10219
The synthesis of (?)‐salinosporamide A, a proteasome inhibitor, is described. The synthesis highlights the assembly of a densely decorated pyrrolidinone core via an aza‐Payne/hydroamination sequence. Central to the success of the synthesis is a late‐stage C?H insertion reaction to functionalize a sterically encumbered secondary carbon. The latter functionalization leads to an enabling transformation where most of the prototypical strategies failed. 相似文献
88.
89.
Tapper AE Long JR Staples RJ Stavropoulos P 《Angewandte Chemie (International ed. in English)》2000,39(13):2343-2346
90.
The occurrence of a heteroatom X (C, N, or O) in the MoFe7S9X core of the iron-molybdenum cofactor of nitrogenase has encouraged synthetic attempts to prepare high-nuclearity M-Fe-S-X clusters containing such atoms. We have previously shown that reaction of the edge-bridged double cubane [(Tp)2Mo2Fe6S8(PEt3)4] (1) with nucleophiles HQ- affords the clusters [(Tp)2Mo2Fe6S8Q(QH)2](3-) (Q = S, Se) in which HQ- is a terminal ligand and Q(2-) is a mu2-bridging atom in the core. Reactions with OH- used as such or oxygen nucleophiles generated in acetonitrile from (Bu3Sn)2O or Me3SnOH and fluoride were examined. Reaction of 1 with Et4NOH in acetonitrile/water generates [(Tp)2Mo2Fe6S9(OH)2]3- (3), isolated as [(Tp)2Mo2Fe6S9(OH)(OC(=NH)Me)(H2O)](3-) and shown to have the [Mo2Fe6(mu2-S)2(mu3-S)6(mu6-S)] core topology very similar to the P(N) cluster of nitrogenase. The reaction system 1/Et4NOH in acetonitrile/methanol yields the P(N)-type cluster [(Tp)2Mo2Fe6S9(OMe)2(H2O)](3-) (5). The system 1/Me3SnOH/F- affords the oxo-bridged double P(N)-type cluster {[(Tp)2Mo2Fe6S9(mu2-O)]2}5- (7), convertible to the oxidized cluster {[(Tp)2Mo2Fe6S9(mu2-O)]2}4- (6), which is prepared independently from [(Tp)2Mo2Fe6S9F2(H2O)](3-)/(Bu3Sn)2O. In the preparations of 3-5 and 7, hydroxide liberates sulfide from 1 leading to the formation of P(N)-type clusters. Unlike reactions with HQ-, no oxygen atoms are integrated into the core structures of the products. However, the half-dimer composition [Mo2Fe6S9O] relates to the MoFe7S9 constitution of the putative native cluster with X = O. (Tp = hydrotris(pyrazolyl) borate(1-)). 相似文献