全文获取类型
收费全文 | 120篇 |
免费 | 1篇 |
专业分类
化学 | 101篇 |
物理学 | 20篇 |
出版年
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 6篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 8篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有121条查询结果,搜索用时 31 毫秒
1.
Iwao Ojima Shin-Ichi Inaba Tetsuo Kogure Makoto Matsumoto Hideyuki Matsumoto Hamao Watanabe Yoichiro Nagai 《Journal of organometallic chemistry》1973,55(1):C4-C6
[RhCl(PPh3)3] is a very effective catalyst for the cleavage of Si-Si bonds by alcohols. 相似文献
2.
Poly(N-isopropylacrylamide) (PNIPAM) has a low critical solution temperature (LCST) at 32°C in water and the hydrophilicity changes through the LCST. The microspheres whose surface was composed of PNIPAM exhibited phase transition behavior around 32°C. Therefore, the interactions between PNIPAM micropheres and granulocytes depended on the temperature. That is, the oxygen consumption and active oxygen production by cells in contact with PNIPAM-containing microspheres and adhesion of the microspheres to the cell surface were more enhanced above the LCST of PNIPAM than below it, whereas no significant temperature dependence of cell–microspheres interaction was observed in nonthermosensitive microsphere systems. It was suggested that the function of cells could be controlled with temperature using the temperature-sensitive microspheres. 相似文献
3.
Asymmetric hydrogenation of dehydrodipeptides, α-acylaminocinnamoyl-(S)-amino esters, catalyzed by rhodium complexes with chiral diphosphines gave either (R)-N-acylphenylalanyl-(S)-amino esters or (S)-N-acylphenylalanyl-(S)-amino esters with high diastereomeric purity up to 98–99% on using proper chiral ligands. 相似文献
4.
N-Acyl-α-amino acids are synthesized by the amidocarbonylation of allylic alcohols catalyzed by homogeneous binary systems which consist of cobalt carbonyl and rhodium (or iron or palladium) complexes. 相似文献
5.
Geney R Sun L Pera P Bernacki RJ Xia S Horwitz SB Simmerling CL Ojima I 《Chemistry & biology》2005,12(3):339-348
A new computational docking protocol has been developed and used in combination with conformational information inferred from REDOR-NMR experiments on microtubule bound 2-(p-fluorobenzoyl)paclitaxel to delineate a unique tubulin binding structure of paclitaxel. A conformationally constrained macrocyclic taxoid bearing a linker between the C-14 and C-3'N positions has been designed and synthesized to enforce this "REDOR-taxol" conformation. The novel taxoid SB-T-2053 inhibits the growth of MCF-7 and LCC-6 human breast cancer cells (wild-type and drug resistant) on the same order of magnitude as paclitaxel. Moreover, SB-T-2053 induces in vitro tubulin polymerization at least as well as paclitaxel, which directly validates our drug design process. These results open a new avenue for drug design of next generation taxoids and other microtubule-stabilizing agents based on the refined structural information of drug-tubulin complexes, in accordance with typical enzyme-inhibitor medicinal chemistry precepts. 相似文献
6.
The hydrosilylation of α,β-unsaturated nitriles and esters such as acrylonitrile, crotononitrile, cinnamonitrile, ethyl and methyl acrylate, ethyl and methyl crotonate and ethyl and methyl methacrylate using tris(triphenylphosphine)chlororhodium as a catalyst is described. The hydrosilylation of α,β-unsaturated nitriles provided α-adduct exclusively in high yield except in the case of trichlorosilane which afforded β-adduct with acrylonitrile. On the other hand, the hydrosilylation of α,β-unsaturated esters gave rather complex results. The selectivity of the reactions was dramatically affected by the substituent of the ester group and that on the β-carbon. Thus, the hydrosilylation of ethyl acrylate with triethylsilane afforded a β-adduct, but, that of ethyl crotonate using the same hydrosilane gave a 1,4-adduct exclusively. Possible mechanisms for these reactions are discussed. 相似文献
7.
[reaction: see text] Highly efficient syntheses of azabicyclo[4.4.0]alkane amino acids were achieved by Rh-catalyzed cyclohydrocarbonylation of dipeptides bearing a terminal olefin moiety and a heteroatom nucleophile. 相似文献
8.
Minoru Umeda Hiroyuki Ojima Mohamed Mohamedi Isamu Uchida 《Journal of Polymer Science.Polymer Physics》2002,40(11):1103-1109
Methanol vapor‐induced membranous changes in a cast‐coated Nafion thin film were studied through current–voltage (I–V) characteristics with an interdigitated microarray (IDA) electrode and atomic force microscopy (AFM). The obtained I–V curves showed that the as‐prepared Nafion film was stable under humidified nitrogen gas; however, the I–V profile dramatically changed with exposure to methanol vapor. Next, the morphology of the film was compared before and after methanol exposure with AFM images. On the basis of our observations, we found that the as‐prepared film had an irregularly complicated microstructure, whereas the structure became homogeneous in appearance after 30 min of exposure to methanol gas. The alternating‐current conductivity data, showing almost the same magnitude before and after exposure, strongly suggested that the I–V profile shift was based on a change in an electrode reaction mechanism induced by a change in the junction at the Nafion/IDA electrode interface. Furthermore, the methanol vapor‐pre‐exposed Nafion was stable for further exposure to methanol vapor, water vapor, or both. With the stabilized film used in combination with the IDA electrode, a reversible change in the magnitude of the current was observed when the methanol/water vapor ratio was varied. This indicated that the electrode reaction had good reproducibility after the treatment. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1103–1109, 2002 相似文献
9.
1-Vinyltetrahydroisoquinolines serve as versatile intermediates for the synthesis of a variety of naturally occurring isoquinoline alkaloids. 1-Vinyl-6,8-dimethoxytetrahydroisoquinoline 4 and 1-vinyl-5,6,7-trimethoxytetrahydroisoquinoline 6 with >90% ee by means of Pd-catalyzed intramolecular asymmetric allylic amination reactions, using MPN and BOP ligands, developed in our laboratory. The fine-tuning capability of the MPN and BOP ligands has played a significant role in the optimization of enantioselectivity. Interesting substituent effect as well as solvent effect on the product selectivity and enantioselectivity was observed. Plausible mechanisms are proposed, which can accommodate various findings, including the critical importance of the activation of the trifluoroamide moiety through its coordination to the Lewis acidic Pd2+ metal center. 相似文献
10.
Formal enantioselective total synthesis of schulzeines A-C was accomplished, featuring highly efficient Pd-catalyzed asymmetric allylic amination using novel diphosphonite ligands (BOPs) to provide 1-vinyltetrahydroisoquinoline key intermediates, as well as Ru-catalyzed ring-closing metathesis reaction to construct the key tricyclic cores in enantiopure form with correct absolute configurations. 相似文献