全文获取类型
收费全文 | 672篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 310篇 |
晶体学 | 2篇 |
力学 | 19篇 |
数学 | 123篇 |
物理学 | 228篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 19篇 |
2016年 | 30篇 |
2015年 | 18篇 |
2014年 | 20篇 |
2013年 | 30篇 |
2012年 | 36篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 20篇 |
2008年 | 26篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 17篇 |
2002年 | 22篇 |
2001年 | 17篇 |
2000年 | 20篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1992年 | 7篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1958年 | 3篇 |
排序方式: 共有682条查询结果,搜索用时 531 毫秒
11.
Published data on the molar absorption coefficients and integral intensities A
0 of vibrations in physically and chemically adsorbed molecules are reviewed. Analysis of published data shows that bonds characterized by high values of the dipole momentum derivative with respect to the normal coordinate change during adsorption toward decreasing this derivative, whereas bonds characterized by a low value of the derivative change toward increasing the derivative. Thus, adsorption results in a decrease in the difference in values of the dipole momentum derivative with respect to the normal coordinate of different bonds compared with the same bonds in the individual molecules. In addition, the interval of changing the molar absorption coefficients for the surface complexes are at least two orders of magnitude lower than that for the same bonds in the molecules in the gas phase. A series for the degree of easiness in detecting complexes on the catalyst surface (the series of decreasing the molar absorption coefficient) is proposed. 相似文献
12.
13.
O. V. Krylov 《Kinetics and Catalysis》2002,43(2):284-289
This paper presents an overview of the plenary lectures and some of the oral and poster presentations at the 4th International Congress on Oxidation Catalysis in Potsdam (Germany). The main topics were the partial oxidation of alkanes and the oxidation of olefins by H2O2. Considerable attention is given to the use of modern physical methods in the mechanistic studies of oxidation catalysis and in the studies of catalyst structures. 相似文献
14.
Mass spectra of 2-aryl-4,6-dioxo-1,3-thiazines were studied and the general fragmentation paths of these compounds determined. Based on mass spectra of compounds with fixed structures, 2-aryl-5,5-dialkyl-4,6-dioxo-1,3-thiazines, 4-alkoxy- and 4-acyloxy-2-aryl-6-oxo-1,3-thiazines, the decomposition paths of the dicarbonyl and hydroxycarbonyl forms were determined. It was concluded on the basis of the obtained data that 2-aryl-4,6-dioxo-1,3-thiazines exist in the gas phase predominantly in the hydroxycarbonyl form.For Communication 63, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1412, October, 1987. 相似文献
15.
I. V. Rogachevskii M. L. MacKey B. F. Shchegolev B. V. Krylov 《Russian Journal of General Chemistry》2002,72(3):472-479
The molecular geometries of a series of steroid hormones including cortisol, 9-fluorocortisol, 6-fluorocortisol, and 9-chlorocortisol were optimized by 3-21G and 6-31G* ab initio calculations. The results of calculations on both levels are well consistent with each other and with the experiment. The conformational changes and electron density redistribution occurring in going from cortisol to its 6- and 9-halo derivatives were discussed. A conclusion was made that the O and F atoms can participate in hydrogen bonding with the corresponding structural groups of glucocorticoid receptors. 相似文献
16.
Capillary electrophoresis (CE) is an important tool of chemical cytometry. Whole-cell analysis using CE starts with cell injection into the capillary by either siphoning or electroosmosis. However, strong adherence of the cell to the support surface can prevent efficient cell injection and lead to irreproducible analysis. Here we evaluated several surfaces as potential cell supports for HT29 cells (human colon adenocarcinoma). These cells strongly adhered to the surface of untreated glass or polystyrene. Hydrophobic coating with dimethyldichlorosilane (DMS) or Sigmacote did not significantly reduce cell adhesion. In contrast, cell adhesion was reduced significantly when the surface was modified with hydrophilic polymers (hydrogels) such as poly(2-hydrohyethyl methacrylate) (PHEMA) and polyvinyl alcohol (PVA). In addition to their pronounced antiadhesive properties, PHEMA and PVA coatings were the most biocompatible (had highest survival of cells in contact with surface). Hydrogel-coated polystyrene plates were tested as a commercial alternative to hydrogel-coated glass slides. The cell adhesive properties of such plates were similar to those of PHEMA and PVA. However, the biocompatibility of the plates was lower than that of the other surfaces tested. Moreover, in contrast to PHEMA- and PVA-coated glass slides, the plates were sensitive to UV light and therefore should not be used when fluorescent image microscopy with UV excitation precedes CE. The analyses of the data obtained showed that PHEMA- and PVA-coated glass slides were the most suitable cell supports for cell injection into the capillary. 相似文献
17.
Munsch TE Slipchenko LV Krylov AI Wenthold PG 《The Journal of organic chemistry》2004,69(17):5735-5741
The electronic structure of dehydro-m-xylylene anion (DMX-) has been investigated by using chemical reactivity studies and electronic structure calculations. DMX- has been generated in the gas phase via the sequential reaction of trimethyl-3,5-bis(trimethylsilylmethyl)phenylsilane with F- and two molecules of F2. Reactivity and thermochemical properties of the ion indicate a phenyl-like anion (1a), consistent with theoretical predictions. Density functional calculations predict a nonplanar triplet anion, with an allenic singlet anion slightly higher in energy. The driving force for the out-of-plane distortion is more efficient charge delocalization that is achieved at lower symmetry. 相似文献
18.
S. Al-Fared F. Zantuti Yu. S. Krylov 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(2):381-391
The use of complexons: nitrilotriacetic (NTA) and diethylenetriaminepentaacetic (DTPA) acids have been studied in extraction systems with main classes of neutral organo phosphorus extractants: phosphates (tributyl phosphate-TBP), phosphonate (diisooctylmethyl phosphonate-DiOMP) and phosphine oxides (triisoamylphosphineoxide-TiAPO) to separate lanthanides of the Ce subgroup. Optimal conditions to use complexon have been determined (extractant and salting agent concentrations). The effect of the type of extractant on the lanthanide distribution coefficients' dependence on pH of equilibrium water solution have been studied in the presence of NTA and DTPA. Unextractable cation displacers have been used to regulate distribution coefficients. The values of lanthanide separation coefficients of Ce group have been determined in extraction systems with neutral phosphorus-containing extraction agents — complexon — salting agent compared with Nd macroconcentrations and for lanthanide microconcentrations in the presence of cation displacer. These systems have been shown to be suitable for lanthanide separation of the cerium group. 相似文献
19.
20.
Yu. A. Simonov M. S. Fonar' E. V. Ganin A. A. Dvorkin G. G. Musienko E. N. Krylov T. I. Malinovskii 《Journal of Structural Chemistry》1992,33(2):278-283
Applied Physics Institute, Moldovian Academy of Sciences. Technical Physics Institute, Ukrainian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 138–144, March–April, 1992. 相似文献