全文获取类型
收费全文 | 322432篇 |
免费 | 1201篇 |
国内免费 | 642篇 |
专业分类
化学 | 132304篇 |
晶体学 | 4187篇 |
力学 | 20918篇 |
综合类 | 7篇 |
数学 | 69973篇 |
物理学 | 96886篇 |
出版年
2019年 | 2292篇 |
2018年 | 18800篇 |
2017年 | 19278篇 |
2016年 | 12319篇 |
2015年 | 3202篇 |
2014年 | 3954篇 |
2013年 | 7424篇 |
2012年 | 11976篇 |
2011年 | 25036篇 |
2010年 | 15736篇 |
2009年 | 16449篇 |
2008年 | 20350篇 |
2007年 | 25042篇 |
2006年 | 5982篇 |
2005年 | 11377篇 |
2004年 | 8725篇 |
2003年 | 8986篇 |
2002年 | 6650篇 |
2001年 | 5350篇 |
2000年 | 4257篇 |
1999年 | 2995篇 |
1998年 | 2817篇 |
1997年 | 2605篇 |
1996年 | 2567篇 |
1995年 | 2244篇 |
1994年 | 2155篇 |
1993年 | 2195篇 |
1992年 | 2184篇 |
1991年 | 2501篇 |
1990年 | 2423篇 |
1989年 | 2513篇 |
1988年 | 2405篇 |
1987年 | 2429篇 |
1986年 | 2251篇 |
1985年 | 2788篇 |
1984年 | 2811篇 |
1983年 | 2451篇 |
1982年 | 2498篇 |
1981年 | 2398篇 |
1980年 | 2208篇 |
1979年 | 2535篇 |
1978年 | 2694篇 |
1977年 | 2689篇 |
1976年 | 2809篇 |
1975年 | 2602篇 |
1974年 | 2525篇 |
1973年 | 2741篇 |
1972年 | 2207篇 |
1971年 | 2007篇 |
1970年 | 1887篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Radiophysics and Quantum Electronics - We consider whether it is possible in principle to retrieve the key parameters of the mixed layer in the upper ocean (its thickness, bulk eddy viscosity and... 相似文献
132.
Siberian Mathematical Journal - Under study are the right-symmetric algebras over a field $ F $ which possess a “unital” matrix subalgebra $... 相似文献
133.
134.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
135.
N. I. Golovina G. N. Nechiporenko G. G. Nemtsev G. P. Dolganova V. P. Roshchupkin D. B. Lempert G. B. Manelis 《Russian Journal of Applied Chemistry》2007,80(1):24-30
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined. 相似文献
136.
In this work the results of the statistical topometric analysis of fracture surfaces of soda-lime-silica glass with and without ionic exchange treatment are reported. In this case, the mechanism of substitution is K+-Na+. atomic force microscopy (AFM) was employed to record the topometric data from the fracture surface. The roughness exponent (ζ) and the correlation length (ξ) were calculated by the variable bandwidth method. The analysis for both glasses (subjected and non-subjected to ionic exchange) for ζ shows a value ∼0.8, this value agrees well with that reported in the literature for rapid crack propagation in a variety of materials. The correlation length shows different values for each condition. These results, along with those of microhardness indentations suggest that the self-affine correlation length is influenced by the complex interactions of the stress field of microcracks with that resulting from the collective behavior of the point defects introduced by the strengthening mechanism of ionic exchange. 相似文献
137.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(12):2163-2164
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic. 相似文献
138.
G. Panina 《Central European Journal of Mathematics》2003,1(2):157-168
All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible
with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples
of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual
polytope. 相似文献
139.
140.
Experimental data on the effect of thallium and sodium impurities on the lattice heat conductivity of PbTe at room temperature
are reported. Because the lattice of lead chalcogenides is strongly polarized near charged impurities, the effect of impurities
on the lattice heat conductivity depends substantially on their charge state. This property of the material has been used
to determine the charge state of the thallium impurity in PbTe. The results obtained argue for a model of quasi-local thallium-impurity
states which assumes low electron-correlation energy at an impurity center.
Fiz. Tverd. Tela (St. Petersburg) 40, 1206–1208 (July 1998) 相似文献