全文获取类型
收费全文 | 139篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 76篇 |
晶体学 | 3篇 |
力学 | 2篇 |
数学 | 40篇 |
物理学 | 19篇 |
出版年
2020年 | 3篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有140条查询结果,搜索用时 218 毫秒
31.
Yang Xi Beckwith Andrew W. Miller John H. Wood Lowell T. 《Central European Journal of Physics》2004,2(4):636-644
The charges in live cells interact with or produce electric fields, which results in enormous dielectric responses, flexoelectricity,
and related phenomena. Here we report on a contraction of Schizosaccharomyces pombe (fission yeast) cells induced by magnetic fields, as observed using a phase-sensitive projection imaging technique. Unlike electric fields, magnetic fields only act
on moving charges. The observed behavior is therefore quite remarkable, and may result from a contractile Lorentz force acting
on diamagnetic screening currents. This would indicate extremely high intracellular charge mobilities. Besides, we observed
a large electro-optic response from fission yeast cells. 相似文献
32.
A statistical procedure is described to help decide whether or not to reject a data point which deviates markedly from a straight-line regression. A Beer's law plot is used to illustrate the procedure. 相似文献
33.
James W. Pavlik Jennifer A. Lowell Vuthichai Ervithayasuporn 《Journal of heterocyclic chemistry》2005,42(7):1253-1255
Reaction of 4,4,4‐trifluoro‐1‐phenyl‐1,3‐butanedione with hydroxylamine led to the formation of 5‐hydroxy‐3‐phenyl‐5‐(trifluoromethyl)‐4,5‐dihydroisoxazole which was dehydrated to 3‐phenyl‐5‐(trifluoro‐methyl)isoxazole. This isomer can also be synthesized by reaction of 4‐chloro‐4‐phenyl‐1,1,1‐trifluoro‐3‐buten‐2‐one with sodium azide. The regioisomer, 5‐phenyl‐3‐(trifluoromethyl)isoxazole was synthesized by reaction of 1,1,1‐trifluoro‐4‐phenylbut‐3‐yn‐2‐one with hydroxylamine and by the reaction of 3‐chloro‐1‐phenyl‐4,4,4‐trifluorobut‐2‐en‐1‐one with sodium azide. Both isomers were characterized by mass and NMR spectroscopy. 相似文献
34.
Zhou S Xu C Wang J Golas P Batteas J Kreeger L 《Langmuir : the ACS journal of surfaces and colloids》2004,20(20):8482-8489
Novel cationic hydroxyethyl cellulose (HEC) polymers with different molecular weights (1.1 x 10(5) to 1.7 x 10(6) g/mol) and ethylene oxide (EO) side chain lengths (1.5-2.9 EO units) were mixed with sodium dodecyl sulfate (SDS) in aqueous solutions. The phase diagrams of cationic HEC-SDS complexes were determined in the dilute polymer concentration regime (< 0.5 wt %) with gradual addition of SDS molecules. The viscosity and structures of the complexes during the phase evolution were studied using rheometry and dynamic light scattering. The gradual addition of SDS first induced interchain associations with the bound SDS aggregates serving as cross-linkers to form an open network structure, producing a very broad size distribution and high viscosities of the complex solutions, and then condensed the network and induced a structure reorganization, resulting in globular aggregates with narrow size distributions. The growth of these globular aggregates in size eventually led to macroscopic sedimentation near charge neutralization. Further addition of SDS randomly broke the sedimentary aggregates into small particles and SDS micelles with low solution viscosities. The effects of molecular weight and EO side chain length of polymers on the phase boundary, viscosity, and structure of cationic HEC-SDS complexes were discussed. 相似文献
35.
36.
Kim SH Perera R Hager LP Dawson JH Hoffman BM 《Journal of the American Chemical Society》2006,128(17):5598-5599
The classical heme-monooxygenase active intermediate, compound I (Cpd-I), incorporates a heme which is oxidized by two equivalents above the resting ferric state, one equivalent associated with a ferryl center, [Fe=O]2+ (FeS = 1), and the other with an active-site radical (RS = 1/2). Theoretical calculations on models of a Cpd-I with a thiolato axial ligand have presented divergent views about its electronic structure. In one picture, the radical is on the porphyrin; in the other, it is on the sulfur. In this report, ENDOR spectroscopy answers the question, does Cpd-I of the enzyme chloroperoxidase contain a porphyrin pi-cation radical or an iron-bound cysteinyl radical: the radical is predominantly on the porphyrin, with spin density on sulfur having an upper bound, rhoS = rhoSmax approximately 0.23. We further suggest that the same answer applies to Cpd-I of cytochromes P450. 相似文献
37.
[structure: see text] Rate constants for two-electron oxidation reactions of Compound I from chloroperoxidase (CPO) with a variety of substrates were measured by stopped-flow kinetic techniques. The thiolate ligand of CPO Compound I activates the iron-oxo species with the result that oxidation reactions are 2 to 3 orders of magnitude faster than oxidations by model iron(IV)-oxo porphyrin radical cations containing weaker binding counterions. 相似文献
38.
We study aspects of the algebraic structure shared by a certain family of recursively generated arrays related to the operation of Nim-addition. We first observe that each individual array represents a countably infinite, commutative loop (in the sense of quasigroups). We then prove that each loop in the family is monogenic (generated by a single element in a non-associative fashion), and use this to determine all loop homomorphisms between members of the family. 相似文献
39.
The Maron theory of nonelectrolyte solutions has been used to analyze the thermodynamic behavior of the system benzene-ethylene dichloride. Excellent agreement with experiment has been obtained for all the thermodynamic properties involved. The analysis also shows that the interaction parameter for this system is small and positive, but it varies sharply with both concentration and temperature. As a result the system is nonideal and complex in behavior, despite the fact that vapor pressure data would tend to suggest near ideality. 相似文献
40.
Dragomir Z. Dokovic Lowell G. Sweet 《Proceedings of the American Mathematical Society》1999,127(11):3169-3174
A (non-associative) algebra , over a field , is called homogeneous if its automorphism group permutes transitively the one dimensional subspaces of . Suppose is a nontrivial finite dimensional homogeneous algebra over an infinite field. Then we prove that for all in , and so for all .