全文获取类型
收费全文 | 109篇 |
免费 | 0篇 |
专业分类
化学 | 94篇 |
力学 | 3篇 |
物理学 | 12篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1987年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 278 毫秒
1.
A rapid and sensitive optical rotation (OR) measurement system using laser light has been developed to meet the demands of flash-photolysis experiments. The optimal OR resolution of the apparatus is 0.3mdeg with 10 μs time constant with single shot. The OR resolution could be easily improved less than 0.1 mdeg with accumulation of data by a kinetic processor. Applications are briefly described for the study of transient conformational change of photochemical intermediates of octopus rhodopsin following a blue light flash. 相似文献
2.
Noboru Matsumura Motoyuki Kusamiya Hiroo Inoue Masanori Yasui Fujiko Iwasaki 《Journal of heterocyclic chemistry》1995,32(4):1269-1275
1,3-Bis(p-substituted-phenylthiocarbamoyl)-2-imidazolidinethiones 3a-f reacted with bromine to give trithiadiazapentalene derivatives 5a-f , bearing the exocyclic C-N double bonds, in moderate yields. The molecular structure of 5b was elucidated by the X-ray crystallographic analysis. The treatment of 5b-f with hydrochloric acid gave the ring-opening products, 1,3-bis(p-substituted-phenylthiocarbamoyl)-2-imidazo-lidinones 9b-f , accompanied by the production of elemental sulfur. Reduction of 5b , 5d , and 5e with sodium borohydride gave the ring-opening compounds, 1,3-bis(p-substituted-phenylthiocarbamoyl)-2-imidazolidines 13b , 13d , and 13e respectively. 相似文献
3.
Yoshio Okamoto Motoyuki Toki Heimei Yuki 《Journal of polymer science. Part A, Polymer chemistry》1979,17(11):3705-3712
S-Methyl thiomethacrylate (methyl thiolmethacrylate, MTMA) was polymerized with a variety of anionic initiators such as n-BuLi, octylpotassium, PhMgBr, and Et2AlNPh2 in toluene and THF. Stereoregularity of the polymer (PMTMA) was determined from the 1H-NMR spectrum of poly(methyl methacrylate), which had been derived from PMTMA, because the α-methyl resonance in the 1H-NMR spectrum of PMTMA was not satisfactorily solved owing to the overlap of pentad signals. The 13C-NMR spectrum of PMTMA also showed the splitting due to pentad sequences. Stereoregularity of PMTMA was always low compared with that of poly(methyl methacrylate), which was prepared under the same reaction conditions. MTMA was much more reactive than methyl methacrylate and methacrylonitrile in the copolymerization with n-BuLi in toluene and in THF at ?78°C. The lower stereoregulation of the polymerization of MTMA and the higher reactivity of MTMA were mainly ascribed to the higher resonance effect of MTMA. 相似文献
4.
Motoyuki Toki 《Journal of Sol-Gel Science and Technology》1994,2(1-3):97-101
This paper describes the attempt to prepare a new group of monodispersed silica-polymer hybrid particles, which consists of silica and amide polymer: poly(vinylpyrrolidone) (PVP) and poly(2-ethyloxazoline) (POXZ). Preparation method is based on the growth of hybrid seeds by the addition of TEOS-polymer solution.Monodispersed PVP-silica hybrid particles of 1.24 µm in diameter were prepared by growing the hybrid seeds of 0.54 µm by the addition of TEOS-PVP solution with ammonia catalyst. In the case of POXZ-silica particles, addition of TEOS-POXZ solution to the solution containing 0.54 µm seeds resulted in monodispersed POXZ-silica hybrid particles and four times repetition of the addition for particle growth gave the hybrid particles of the diameter of 1.6 µm.Improvement of mechanical properties of hybrid particles was observed when the particles were heated at 100 200°C. 相似文献
5.
Tadahiro Kato Motoyuki Tanaka Shin‐suke Takagi Keita Nakanishi Masahiro Hoshikawa 《Helvetica chimica acta》2004,87(1):197-214
The synthesis of kempa‐6,8‐dien‐3β‐ol ( 4a ), as a synthetic leading model of the natural product 4b , was carried out starting from intermediate 12 , the synthetic route of which has been developed previously (Scheme 1). The conversion of 12 to the model compound 4a involved the elaboration of three structure modifications by three processes, Tasks A, B, and C (see Scheme 2). Task A was achieved by epoxy‐ring opening of 41 with Me3SiCl (Scheme 9), and Task B being performed by oxidation at the 13‐position, followed by hydrogenation, and then epimerization (Schemes 4 and 5). The removal of the 2‐OH group from 12 (Task C) was achieved via 30b according to Scheme 6, whereby 30b was formed exclusively from 30a / 31a 1 : 1 (Scheme 7). In addition, some useful reactions from the synthetic viewpoint were developed during the course of the present experiments. 相似文献
6.
A simple protocol that uses [OsIII(OH)(H2O)(L ‐N4Me2)](PF6)2 ( 1 ; L ‐N4Me2=N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)pyridinophane) as a catalyst and H2O2 as a terminal oxidant for efficient cis‐1,2‐dihydroxylation of alkenes is presented. Unfunctionalized (or aliphatic) alkenes and alkenes/styrenes containing electron‐withdrawing groups are selectively oxidized to the corresponding vicinal diols in good to excellent yields (46–99 %). In the catalytic reactions, the stoichiometry of alkene:H2O2 is 1:1, and thus the oxidant efficiency is very high. For the dihydroxylation of cyclohexene, the catalytic amount of 1 can be reduced to 0.01 mol % to achieve a very high turnover number of 5500. The active oxidant is identified as the OsV(O)(OH) species ( 2 ), which is formed via the hydroperoxide adduct, an OsIII(OOH) species. The active oxidant 2 is successfully isolated and crystallographically characterized. 相似文献
7.
8.
Hiroshi Ohguro Norihiko Yoshida Hideo Shindou John W. Crabb Krzysztof Palczewski Motoyuki Tsuda 《Photochemistry and photobiology》1998,68(6):824-828
Abstract— Light-dependent phosphorylation of rhodopsin (Rho) is a first step in the desensitization of the signaling state of the receptor during vertebrate and invertebrate visual transduction. We found that only 358 Ser of the photoac-tivated octopus Rho (oRho*) was phosphorylated by octopus rhodopsin kinase (oRK). Tryptic truncation of the C-terminal PPQGY repeats of oRho that follow the phosphorylation region did not influence spectral or G-protein activation properties of oRho but abolished phos phorylation. Despite significant structural differences between oRK and mammalian RK, these results provide i further evidence of the importance of singly phosphorylated species of Rho* in the generation of arrestin binding sites. 相似文献
9.
Kato S Matsumoto T Ishi-i T Thiemann T Shigeiwa M Gorohmaru H Maeda S Yamashita Y Mataka S 《Chemical communications (Cambridge, England)》2004,(20):2342-2343
Novel donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) type 2,1,3-benzothiadiazole fluorescent dyes connected to the N,N-diarylamino terminus via various type pi-conjugate spacers exhibits large two-photon absorption cross-sections and high fluorescent quantum yields in orange-red color. 相似文献
10.
Generation of carbocations by the "cation pool" method followed by reaction with dimethyl sulfoxide (DMSO) gave the corresponding alkoxysulfonium ions. Alkoxysulfonium ions could also be generated by in situ DMSO trapping of electrochemically generated carbocations. The resulting alkoxysulfonium ions were transformed into carbonyl compounds by treatment with triethylamine. The present integrated electrochemical-chemical oxidation can be applied to the oxidation of diarylmethanes to diaryl ketones, toluenes to benzaldehydes, and aryl-substituted alkenes to 1,2-diketones. Moreover, the oxidation of unsaturated compounds bearing a nucleophilic group in an appropriate position gives cyclized carbonyl compounds. 相似文献