全文获取类型
收费全文 | 592113篇 |
免费 | 31215篇 |
国内免费 | 21314篇 |
专业分类
化学 | 328643篇 |
晶体学 | 9070篇 |
力学 | 27680篇 |
综合类 | 412篇 |
数学 | 70488篇 |
物理学 | 208349篇 |
出版年
2021年 | 4947篇 |
2020年 | 5698篇 |
2019年 | 6524篇 |
2018年 | 7876篇 |
2017年 | 8489篇 |
2016年 | 11999篇 |
2015年 | 8919篇 |
2014年 | 11981篇 |
2013年 | 28118篇 |
2012年 | 22376篇 |
2011年 | 27926篇 |
2010年 | 23342篇 |
2009年 | 23170篇 |
2008年 | 24158篇 |
2007年 | 23512篇 |
2006年 | 21926篇 |
2005年 | 20389篇 |
2004年 | 19881篇 |
2003年 | 17071篇 |
2002年 | 16764篇 |
2001年 | 18693篇 |
2000年 | 14112篇 |
1999年 | 11725篇 |
1998年 | 9756篇 |
1997年 | 9320篇 |
1996年 | 9394篇 |
1995年 | 8937篇 |
1994年 | 8826篇 |
1993年 | 8763篇 |
1992年 | 9081篇 |
1991年 | 8818篇 |
1990年 | 8233篇 |
1989年 | 8230篇 |
1988年 | 8144篇 |
1987年 | 7498篇 |
1986年 | 7180篇 |
1985年 | 8828篇 |
1984年 | 9108篇 |
1983年 | 7086篇 |
1982年 | 7735篇 |
1981年 | 7488篇 |
1980年 | 7133篇 |
1979年 | 7369篇 |
1978年 | 7608篇 |
1977年 | 7471篇 |
1976年 | 7702篇 |
1975年 | 6666篇 |
1974年 | 6570篇 |
1973年 | 6892篇 |
1972年 | 4885篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
992.
Magnetic Properties of the Cobaltates Na6CoS4, Na6CoSe4, and K6CoS4 The alkali metal cobalt chalcogenides Na6CoS4, Na6CoSe4, and K6CoS4 crystallize in the space group P63mc with Z = 4. The structure is characterized by isolated [CoX4]-tetrahedra. The magnetic susceptibilities show Curie-Weiss behaviour. The deviations at low temperatures are caused by antiferromagnetic interactions. The magnetic moments are discussed with regard to ligand-field parameters. 相似文献
993.
Lizeng Wang Chengsong Ma Xiaoli Zhang Yibing Ren Yong Yu 《Fresenius' Journal of Analytical Chemistry》1995,351(7):689-691
The electrochemical behavior of the copper-tyrosine complex has been studied by linear-sweep adsorption voltammetry. In 0.02 mol/L Na2HPO4 buffer solution (pH=9.6), the complex can be adsorped on a hanging mercury drop electrode and reduced at a peak potential of about –0.42 V (vs. SCE). The secondary derivative peak height is linear proportional to the concentration of tyrosine in the range 1.0×10–7–5.0×10–5 mol/L. The detection limit is 5×10–8 mol/L.Project supported by the Provincial Science Foundation of Shandong Province 相似文献
994.
Modified Stern-Volmer equation is obeyed by bovine serum albumin (BSA)-iodide system showing selective quenching of tryptophanyl
fluorescence of BSA. The fraction of accessible protein fluorescence is 0.56 and the effective Stern-Volmer constant is 290
M-1 at pH 7.4 in 0.005 M phosphate buffer at 25°C. Collisional quenching is operative both in the BSA -I−1 system and the model system, tryptophan-I−1. It is supported by the observed relationship between the ratio of quenching rate constants (k
q
) and diffusion coefficients and alsok
q
with bulk viscosity. 相似文献
995.
Armenise I. Capitelli M. Colonna G. Koudriavtsev N. Smetanin V. 《Plasma Chemistry and Plasma Processing》1995,15(3):501-528
Plasma Chemistry and Plasma Processing - Nonequilibrium nitrogen dissociation-recombination kinetics in the boundary layer and on the surface of a solid body during hypersonic flow. the subsequent... 相似文献
996.
We study the conjugate boundary-value problem with boundary conditions whose orders can be as large as the order of the differential equation or larger. We construct the Green's function of the problem over the entire space when the separating surface is a hyperplane, and we describe its properties. Bibliography: 6 titles.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 30, 1989, pp. 20–24. 相似文献
997.
998.
Barium ferrite particulates prepared by a salt-melt method 总被引:1,自引:0,他引:1
Tsung-Shune Chin S.L. Hsu M.C. Deng 《Journal of magnetism and magnetic materials》1993,120(1-3):64-68
Barium ferrite particulates have been prepared by coprecipitation and calcination in a flux of NaCl-KCl. It was found that a flux containing more than 30 wt% KCl tends to seriously deteriorate the magnetic properties of resultant perticulates. The flux with 10 wt% KCl or less showed promising results. A Ba(CoZr)0.75Fe10.5O19 particulate showed the best properties, i.e., a saturation magnetization of 68.5, a squareness ratio of 0.49, and a coercivity of 1280 Oe, when calcined in NaCl at 900°C for 4 h. 相似文献
999.
The microwave subsidiary absorption threshold in tangentially magnetized yttrium-iron-garnet (YIG) films was measured as a function of the static magnetic field, film thickness and decrease in the 0.3–3 μm range is observed. The effect is explained quantitatively by using modified Damon-Eshbach dispersion relations which take into account exchange interactions.
The effect of temperature on hcrit, the smallest threshold field amplitude, in the 250<T< 450 K temperature range can be expressed by an empirical relationship hcrit Ms(T)-1.6 where Ms is the saturation magnetization. This hcrit vs Ms relationship is similar to that obtained for the magnetization dependence of parallel pump thresholds in Li-Ti ferrite compounds. 相似文献
1000.
We discuss the possible new electroweak interactions which may be generated by the Higgs sector at the scale of theZ mass. For this purpose, we give a set ofSU(2)×U(1) gauge invariant operators constructed in terms ofW, Z, γ and Higgs fields which in the unitary gauge describe all possible γWW andZWW anomalous couplings. The dimension of these operators varies from 6 to 12. This fact allows us to consider various scenaria for the manifestations of the New Physics. We conclude that the underlying dynamics induced by the Higgs sector can be tested through a model-independent amplitude analysis of gauge boson pair production at LEP2 and future colliders. 相似文献