全文获取类型
收费全文 | 600篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
化学 | 449篇 |
晶体学 | 12篇 |
力学 | 7篇 |
数学 | 26篇 |
物理学 | 122篇 |
出版年
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 8篇 |
2013年 | 28篇 |
2012年 | 35篇 |
2011年 | 29篇 |
2010年 | 17篇 |
2009年 | 22篇 |
2008年 | 39篇 |
2007年 | 35篇 |
2006年 | 28篇 |
2005年 | 22篇 |
2004年 | 28篇 |
2003年 | 30篇 |
2002年 | 27篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 3篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 31 毫秒
1.
Makoto Sakata Takafumi Itsubo Yutakata Moritomo Yasuo Ohishi 《Journal of Physics and Chemistry of Solids》2004,65(12):1973-1976
The experimental and analytical method of the high-pressure powder experiment at BL10XU, SPring-8, is described. There is no doubt that BL10XU must be one of the most appropriate beam lines for high pressure X-ray diffraction experiment taking advantage of third generation synchrotron source. As an example of the advanced charge density study under high pressure, the structural change of Cs2Au2Br6 by applying pressure is studied by Rietveld/MEM analysis. It reveals that the structural change of Cs2Au2Br6 by applying pressure occurs basically at electron level, such as valence state change and chemical bonding, which may be called the electronic phase transition. 相似文献
2.
We investigate low-temperature behaviors of a system with chirality-pair interaction on a one-dimensional lattice. In the course of the investigation, we evaluate asymptotic forms of the characteristic values of the integral equation satisfied by the Mathieu functions. It turns out that the low-temperature behavior of correlation length of the chirality-pair correlation function is different from the one for the Ising model of spin ±1 but akin to the one for the Ising model of infinite spin. 相似文献
3.
4.
5.
Oishi S Kamano T Niida A Odagaki Y Hamanaka N Yamamoto M Ajito K Tamamura H Otaka A Fujii N 《The Journal of organic chemistry》2002,67(17):6162-6173
Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres corresponding to dipeptides having one N-methylamino acid, and application to bioactive peptides, are described. In a key reaction introducing the chiral alpha-alkyl group of the isosteres, organocopper-mediated alkylation of syn-beta-methylated gamma-mesyloxy-alpha,beta-enoate 26a afforded E- and Z-isomers of anti-S(N)2' products in a solvent-dependent manner. The resulting two isosteres, D-Phe-psi[(E)-CH=CMe]-L-Val 27a and D-Phe-psi[(Z)-CH=CMe]-L-Val 28b, which corresponded to trans- and cis-conformers of D-Phe-L-MeVal, respectively, were utilized in a structure-activity relationship study on cyclic RGD peptides 1 and 2, in company with a psi[(E)-CH=CH]-type alkene dipeptide isostere, D-Phe-psi[(E)-CH=CH]-L-Val. The cyclic isostere-containing pseudopeptides 3, 4, and 40 were synthesized and biological activity against integrin alpha(V)beta(3) and alpha(IIb)beta(3) receptors were also evaluated. 相似文献
6.
T. Ohishi S. Maekawa T. Ishikawa D. Kamoto 《Journal of Sol-Gel Science and Technology》1997,8(1-3):511-515
A new technique for preparing anti-reflection/anti-static thin films for CRTs at low temperature has been developed. Double-layered
films of SiO2/SnO2 were formed on a CRT panel surface by the sol-gel method using photoirradiation. The new method makes it possible to reduce
heat treatment temperature (°C) by almost 50% and treatment time to approximately 33% of the conventional levels. 相似文献
7.
8.
Yoshihiko Nishimori Katsuhiko Kanaizuka Dr. Masaki Murata Dr. Hiroshi Nishihara Prof. 《化学:亚洲杂志》2007,2(3):367-376
Films of linear and branched oligomer wires of Fe(tpy)2 (tpy=2,2′:6′,2′′‐terpyridine) were constructed on a gold‐electrode surface by the interfacial stepwise coordination method, in which a surface‐anchoring ligand, (tpy? C6H4N?NC6H4? S)2 ( 1 ), two bridging ligands, 1,4‐(tpy)2C6H4 ( 3 ) and 1,3,5‐(C?C? tpy)3C6H3 ( 4 ), and metal ions were used. The quantitative complexation of the ligands and FeII ions was monitored by electrochemical measurements in up to eight complexation cycles for linear oligomers of 3 and in up to four cycles for branched oligomers of 4 . STM observation of branched oligomers at low surface coverage showed an even distribution of nanodots of uniform size and shape, which suggests the quantitative formation of dendritic structures. The electron‐transport mechanism and kinetics for the redox reaction of the films of linear and branched oligomer wires were analyzed by potential‐step chronoamperometry (PSCA). The unique current‐versus‐time behavior observed under all conditions indicates that electron conduction occurs not by diffusional motion but by successive electron hopping between neighboring redox sites within a molecular wire. Redox conduction in a single molecular wire in a redox‐polymer film has not been reported previously. The analysis provided the rate constant for electron transfer between the electrode and the nearest redox‐complex moiety, k1 (s?1), as well as that for intrawire electron transfer between neighboring redox‐complex moieties, k2 (cm2 mol?1 s?1). The strong effect of the electrolyte concentration on both k1 and k2 indicates that the counterion motion limits the electron‐hopping rate at lower electrolyte concentrations. Analysis of the dependence of k1 and k2 on the potential gave intrinsic kinetic parameters without overpotential effects: k10=110 s?1, k20=2.6×1012 cm2 mol?1 s?1 for [n Fe 3 ], and k10=100 s?1, k20=4.1×1011 cm2 mol?1 s?1 for [n Fe 4 ] (n=number of complexation cycles). 相似文献
9.
Yamamoto Y Ishii J Nishiyama H Itoh K 《Journal of the American Chemical Society》2004,126(12):3712-3713
The Ru(II)-catalyzed [2+2+2] cyclotrimerization of alkynylboronates, propargyl alcohol, and terminal alkynes proceeded chemo- and regioselectively to give rise to arylboronates, which were subjected to Suzuki-Miyaura cross-coupling with aryliodides to afford highly substituted biaryls in 53-76% yields. 相似文献
10.
Eight 1,2-diarylethylenediamines in the meso- or DL-form produce fluorescence when heated with reducing carbohydrates in an alkaline medium. Of the diamines, meso-1,2-bis(4-methoxyphenyl)ethylenediamine is the most favourable reagent for reducing carbohydrates, including 2- deoxy sugars, amino sugars and sialic acids. The reagent permits the fluorimetric determination of reducing carbohydrates at concentrations as low as 0.2–0.9 nmol ml?1. 相似文献