全文获取类型
收费全文 | 1985篇 |
免费 | 6篇 |
专业分类
化学 | 991篇 |
晶体学 | 27篇 |
力学 | 86篇 |
综合类 | 1篇 |
数学 | 176篇 |
物理学 | 710篇 |
出版年
2021年 | 19篇 |
2020年 | 33篇 |
2019年 | 31篇 |
2018年 | 60篇 |
2017年 | 58篇 |
2016年 | 67篇 |
2015年 | 23篇 |
2014年 | 60篇 |
2013年 | 74篇 |
2012年 | 57篇 |
2011年 | 75篇 |
2010年 | 63篇 |
2009年 | 64篇 |
2008年 | 62篇 |
2007年 | 70篇 |
2006年 | 56篇 |
2005年 | 34篇 |
2004年 | 40篇 |
2003年 | 51篇 |
2002年 | 45篇 |
2001年 | 37篇 |
2000年 | 41篇 |
1999年 | 26篇 |
1998年 | 25篇 |
1997年 | 22篇 |
1994年 | 17篇 |
1990年 | 16篇 |
1989年 | 20篇 |
1988年 | 23篇 |
1986年 | 19篇 |
1985年 | 28篇 |
1984年 | 33篇 |
1983年 | 16篇 |
1981年 | 30篇 |
1980年 | 29篇 |
1979年 | 25篇 |
1978年 | 30篇 |
1977年 | 36篇 |
1976年 | 24篇 |
1975年 | 23篇 |
1972年 | 22篇 |
1971年 | 19篇 |
1970年 | 23篇 |
1969年 | 15篇 |
1968年 | 33篇 |
1967年 | 22篇 |
1965年 | 25篇 |
1964年 | 20篇 |
1960年 | 21篇 |
1959年 | 16篇 |
排序方式: 共有1991条查询结果,搜索用时 62 毫秒
1.
2.
Template synthesis of a nickel(II) chelate with an (N'N'S'S)-donor ligand, 4'6-dimethyl-2'8-di-thio-3'7-diaza-5-oxanonanedithioamide-1'9, with a metal ion:ligand ratio of 1:1 is realized in getalin-immobilized nickel(II) hexacyanoferrate(II) matrices contacting with aqueous solutions containing dithiox-amide, acetaldehyde (pH > 10), where the latter two compounds play the role of ligand synthons. On directcontact of dithioxamide and acetaldehyde in the solution in the absence of Ni(II), the above (N,N,S,S)-donorligand does not form, and no nickel(II) chelates with this ligand can be obtained by reactions of known nickel(II) dithiooxamide complexes with acetaldehyde. 相似文献
3.
Hyperfine Interactions - Rotational J=1→J=0 transitions in muonic molecule, (3Heμd) J ++, in [(3Heμd)++,2e]–D and [(3Heμd)++,e]+–D collisions are considered. The... 相似文献
4.
5.
Water-soluble polymers of acrylamide and acrylic acid that contain fullerene (more than 90% C60) have been prepared by the low-temperature radiation-induced living polymerization. In the absorption spectra of these polymers, a monotonically decaying absorption typical of the covalently bound fullerene or its associates is observed in the range 240–700 nm. The radiation initiation of the process allows preparation of high-purity polymers useful for designing medicinal preparations. 相似文献
6.
I. N. Medvedev G. A. Mikhailov 《Computational Mathematics and Mathematical Physics》2006,46(8):1442-1458
The efficiency of the “value” and “partial value” modeling related to the construction of a modeling distribution for an auxiliary random variable by multiplying the initial density by a value function is investigated. The value function usually corresponds to a solution of the adjoint equation. Conditions under which the value modeling of the initial distribution reduces the variance compared to the direct simulation are obtained. It is proved that the variance of the weighted estimate is bounded in the case of the partial value modeling. This proposition provides a basis for a method for determining whether or not the variance of the weighted estimate is bounded. This method uses the majorizing adjoint equation. Using a practically important problem in transport theory as an example, the asymptotic optimization of the distribution of the mean free path is presented. The application of the proposed method of the investigation of the variance boundedness for the analysis of the classical exponential transformation method of simulating the mean free path of a particle in the one-dimensional and the spherical variants is discussed. 相似文献
7.
We construct weighted modifications of statistical modeling of an ensemble of interacting particles which is connected with approximate solution of a nonlinear Boltzmann equation. 相似文献
8.
S. V. Lindeman Yu. T. Struchkov I. A. Khotina V. N. Mikhailov A. L. Rusanov 《Russian Chemical Bulletin》1994,43(11):1873-1879
The crystal structure of 1,3,5-tris[4-(phenylethynyl)phenyl]benzene (1) has been investigated. Compound1 represents a model of the repeating unit of the most typical polyphenylene, which contains 1,3,5-trisubstituted benzene rings (chain centers) and acetylenic groups (complex-forming and cross-linking centers) in the main chain. The acetylene groups of neighboring molecules have a tendency to close mutual arrangement, which is favorable for their topochemical interaction. However, the relative conformational rigidity of molecules1 restricts not only the possibility of the optimal adjustment of the reactive sites of neighboring molecules to one another, but also hampers the close packing of molecules in the crystal, which contains channels filled by the solvent molecules (chloroform).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1986–1992, November, 1994.The work was carried out with the financial support of the International Science Foundation and the American Crystallographic Association. 相似文献
9.
10.
I. I. Milman E. V. Moiseykin S. V. Nikiforov S. G. Mikhailov V. I. Solomonov 《Radiation measurements》2004,38(4-6):443
The spectra of pulsed cathodoluminescence (PCL) and thermoluminescence (TL) in TLD-500 detectors, which were exposed to a strong beam from a pulsed electron accelerator, have been studied. Additional bands in the PCL spectrum and new peaks in the TL curves, which are due to impurity ions, have been revealed. Luminescence bands of F- and F+-centers cannot be used in the dosimetry of strong electron beams using TLD-500 detectors because of the saturation of dose dependence and the decrease in the TL yield. It is shown that high doses from these beams can be measured by recording TL in the luminescence band of impurity titanium ions. 相似文献