全文获取类型
收费全文 | 3328篇 |
免费 | 60篇 |
国内免费 | 28篇 |
专业分类
化学 | 1572篇 |
晶体学 | 33篇 |
力学 | 107篇 |
数学 | 568篇 |
物理学 | 1136篇 |
出版年
2022年 | 21篇 |
2021年 | 78篇 |
2020年 | 56篇 |
2019年 | 75篇 |
2018年 | 92篇 |
2017年 | 89篇 |
2016年 | 110篇 |
2015年 | 78篇 |
2014年 | 111篇 |
2013年 | 150篇 |
2012年 | 191篇 |
2011年 | 185篇 |
2010年 | 146篇 |
2009年 | 142篇 |
2008年 | 204篇 |
2007年 | 193篇 |
2006年 | 167篇 |
2005年 | 158篇 |
2004年 | 174篇 |
2003年 | 102篇 |
2002年 | 110篇 |
2001年 | 84篇 |
2000年 | 60篇 |
1999年 | 51篇 |
1998年 | 50篇 |
1997年 | 29篇 |
1996年 | 35篇 |
1995年 | 36篇 |
1994年 | 35篇 |
1993年 | 24篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1976年 | 15篇 |
1975年 | 15篇 |
1974年 | 14篇 |
1973年 | 12篇 |
1972年 | 14篇 |
1971年 | 16篇 |
1970年 | 10篇 |
1969年 | 13篇 |
排序方式: 共有3416条查询结果,搜索用时 265 毫秒
21.
Processes of electronic excitation energy transfer (EEET) in H2O+D2O solutions within reversed micelles with different degrees of hydration were studied. It is ascertained that the structure of solutions forms a cluster distribution of interacting molecules having a fractal dimensionality. As a result, in regions with a locally high concentration of the dye molecules, an increase in the EEET efficiency is observed. Solubilization by reversed micelles leads to destruction of the cluster structure of the water system, with the dependence of the EEET efficiency on the degree of hydration being nonmonotonic. As the degree of hydration increases, the inhomogeneities of the structure inherent in bulk water are restored. 相似文献
22.
Results of investigations into the physical properties of a number of new nonlinear crystals are presented. The parameters of frequency converters manufactured on their basis are compared, and second-harmonic generation of CO2 lasers first excited by frequency conversion in LiInSe2, AgGa1– x
InxSe2, AgxGaxGexS2(1 + x), and Hg1–x
CdxGa2S4 crystals is investigated. The superiority of HgGa2S4, Hg1–x
CdxGa2S4, and AgGa1–x
InxSe2 over the well-known crystals has been demonstrated for frequency conversion both within the middle-IR range and from the visible range to the middle-IR range. Advantages of LiInSe2 and AgGa1–x
InxSe2 crystals are demonstrated for the direct frequency conversion of femtosecond laser radiation to the middle-IR range compared to the cascade frequency conversion and direct frequency conversion in LiInS2 crystals. 相似文献
23.
Hyperfine structure of a hydrogen-like atom due to orbit-orbit,spin-orbit,and spin-spin interactions
A nonrelativistic model of a hydrogen-like atom is considered. This model is used to calculate corrections to the energy spectrum of the atom. The analysis is based on a Hamiltonian that includes the intratomic fields generated by the electron and the nucleus. 相似文献
24.
E. Sh. Finkel'shtein N. V. Ushakov N. A. Pritula E. A. Andreev N. A. Platé 《Russian Chemical Bulletin》1992,41(1):185-187
The thermally initiated and platinum-catalyzed polymerization of 1-silacyclobutanes with substitutents containing a trimethylsilyl group was carried out. Soluble, high-molecular-weight, heterochain siltrimethylene polymers were obtained, containing trimethylsilyl groups removed from the main chain by various bridges.A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 117912 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 223–225, January, 1992. 相似文献
25.
Yuri Borovskikh 《Acta Appl Math》1994,35(3):213-298
U-statistics in Banach spaces are considered and thoroughly investigated. The martingale structure, estimates of moments, the law of large numbers, the central limit theorem, the invariance principle, estimates of the rate of convergence, and large deviations are established 相似文献
26.
The proposed model of laser plasma emission spectrum formation enables us to determine the absolute value of the laser pulse
to plasma emitted radiation conversion factor, profile of the emission spectrum, and frequency distribution of the intensity
and energy in the emitted spectra. This is of interest for laser plasma diagnostics and provides a means for direct calculation
of the number of excited nuclei in dependent on the parameters of laser pulse.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
27.
28.
Yuri L. Mikhlin Alexander S. Romanchenko Alexander A. Shagaev 《Applied Surface Science》2006,252(16):5645-5658
Natural n-type PbS single crystals have been studied using AFM, STM and STS after long-term oxidation in air at ambient temperatures and extensive etching in aqueous acid solutions, in contrast to previous work devoted to initial corrosion of fresh surfaces. The exposure of PbS to atmosphere at high relative humidity for several days yields widespread loose oxidation products; the process is much slower at low humidity. Surface morphologies diverge after the treatment in 1 M perchloric and hydrochloric acid solutions at room temperature and become widely different at elevated temperatures, displaying commonly etch pits up to several micrometers in size and depth along with rather uniformly distributed 20-100 nm protrusions of PbS phase. The changes both in topography and semiconducting properties of PbS found by tunneling spectroscopy have been explained in terms of the non-uniform distribution of donor- and acceptor-type defects D+/D− in the metal depleted surface layer, which are generated by chemical reactions and, in turn, determine the rates of the PbS corrosion. In particular, the D− centers exhibit a self-catalyzing effect on the non-oxidative local dissolution of PbS in HCl media, resulting in the deep etch pits. 相似文献
29.
Yuri Bilu 《Monatshefte für Mathematik》2002,137(1):1-3
We correct an inaccuracy in the papers of Le, Mignotte, and Bugeaud on the generalized Ramanujan-Nagell equation.
Received June 23, 2001 相似文献
30.