全文获取类型
收费全文 | 214篇 |
免费 | 5篇 |
专业分类
化学 | 177篇 |
晶体学 | 1篇 |
数学 | 9篇 |
物理学 | 32篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2016年 | 4篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1965年 | 4篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有219条查询结果,搜索用时 109 毫秒
211.
N. Takamura K. Taguchi T. Gunji Y. Abe 《Journal of Sol-Gel Science and Technology》1999,16(3):227-234
The sol-gel reactions of methyl- and vinyltrimethoxysilane under controlled conditions provided the corresponding polysilsesquioxanes and flexible thin films on further condensation of the precursors. Silicon oxycarbides containing a large amount of free carbon 58 mol% and 90 mol% were obtained in high yields 90 wt% on pyrolyzing the precursors of polymethyl-and polyvinylsilsesquioxane at 1400°C under N2 atmosphere, respectively. Moreover, pyrolytic polycondensation of polyvinylsilsesquioxane was found to give the silicon oxycarbide ceramic films without deformations and cracks. The composition and properties of films were investigated. 相似文献
212.
A Ti-TPyP reagent, i.e. an acidic aqueous solution of oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) complex, TiO(tpyp), was previously developed as a highly sensitive and specific reagent for determining hydrogen peroxide. In the present work, the reaction specificity of the TiO(tpyp) complex to hydrogen peroxide was clarified based on ab initio calculations. The results provide a well-grounded argument for determining hydrogen peroxide using the Ti-TPyP reagent experimentally. 相似文献
213.
Hiroyoshi Takamura Junki Ando Takeshi Murata Daisuke Uemura 《Tetrahedron letters》2008,49(31):4626-4629
The stereoselective synthesis of the C79-C96 fragment of symbiodinolide is described in which the spiroacetalization and Kotsuki coupling are the key steps. 相似文献
214.
Kiyoko Furuya 《Israel Journal of Mathematics》1989,68(1):89-101
The Cauchy problemdu/dt =Au(t),u(0) =u
0∈D(A) has analytic solutions whenA has first and second Gateaux derivatives along the solution curve in a certain weak sense. HereA is a maximal monotone operator in a complex Hilbert space. 相似文献
215.
H. Kojima Y. Fukuzawa T. Manabe S. Takamura T. Okada N. Ohno 《Czechoslovak Journal of Physics》2003,53(10):895-902
We achieved a potential well more than fifty times deeper than the plasma electron temperature, down to -0.3 kV with the electrode biasing, by the cross-field radial arcing current of up to 150 A which flows between the small electron-emitting electrode (LaB6) inserted to the plasma center and the stainless-steel wall of vacuum chamber. The empirical scaling of the radial resistance of plasma R
r on the radial arcing current I
b and the toroidal magnetic field B
T is found to be R
r I
b
-1.2
B
T
1.0. Structural dynamics of negative potential well formation is observed: the potential dip propagates from the plasma core to the periphery. The ion saturation current also increases, starting from the inner region. The fluctuation frequency in I
sat changes abruptly from 200 kHz to 30 kHz in a time of around 0.25 ms after negative biasing. 相似文献
216.
As a type of interaction of acetylcholine and cholinergic and anticholinergic drugs with a charged surface, their adsorption onto a gold electrode has been examined by measuring the specular reflectivity and differential capacity of the electrode-solution interface.Based on the adsorption potential profiles, the drugs have been divided into three groups: (I) carbamylcholine and methacholine; (II) tetraethylammonium ion and hexamethonium; (III) nicotine, atropine, scopolamine and pilocarpine. Group I includes cholinergic drugs. Group II and III include antichilinergic drugs whose adsorptivity is stronger than that of acetylcholine. The results of the adsorption of acetylcholine and drugs onto a charged electrode surface should provide information about the competitive inhibitory effects on the attachement of acetylcholine to receptor sites. 相似文献
217.
Tokihiro Tanaka Yuto Murai Takayuki Kishi Hiroyoshi Takamura Isao Kadota 《Tetrahedron letters》2018,59(8):763-766
A convergent total synthesis of (?)-dactylolide is described. Constructing the 2,6-disubstituted exo-methylene THP moiety was achieved by the intramolecular allylation of α-acetoxy ether. The cyclization precursor was prepared from two segments, an alcohol and carboxylic acid derivatives, by esterification followed by reductive acetylation. 相似文献
218.
Ono M Takamura C Sugita F Masuoka C Yoshimitsu H Ikeda T Nohara T 《Chemical & pharmaceutical bulletin》2007,55(4):551-556
Two new steroid glycosides, named trikamsterosides A and B, and a new sesquiterpenoid glycoside named trikamsesuquiside A were isolated from the underground parts of Trillium kamtschaticum PALL. along with 18 known compounds comprising 12 steroids, one sesquiterpenoid glycoside, one phenylpropanoid, one flavonoid glycoside, and three phenylpropanoid sucrose esters. Their chemical structures were determined on the basis of spectroscopic data and chemical evidence. Among them, one phenylpropanoid sucrose ester showed almost the same radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl as that of alpha-tocopherol. 相似文献
219.
Kashiwada A Tsuboi M Takamura N Brandenburg E Matsuda K Koksch B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(22):6179-6186
A weakly acidic pH-responsive polypeptide is believed to have the potential for an endosome escape function in a polypeptide-triggered delivery system. For constructing a membrane fusion device with pH-responsiveness, we have designed novel polypeptides that are capable of forming an α2 coiled coil structure. Circular dichroism spectroscopy reveals that a polypeptide, AP-LZ(EH5), with a Glu and His salt-bridge pair at a staggered position in the hydrophobic core forms a stable coiled coil structure only at endosomal pH values (pH 5.0 to 5.5). On the basis of their endosomal-pH responsiveness, a boronic acid/polypeptide conjugate (BA-H5-St) was also designed as a pilot molecule to construct a pH-responsive, one-way membrane fusion system with a sugarlike compound (phosphatidylinositol: PI)-containing liposome as a target. Membrane fusion behavior was characterized by lipid-mixing, inner-leaflet lipid-mixing, and contents-mixing assays. These studies reveal that membrane fusion is clearly observed when the pH of the experimental system is changed from 7.4 (physiological condition) to 5.0 (endosomal condition). 相似文献