全文获取类型
收费全文 | 356816篇 |
免费 | 7106篇 |
国内免费 | 4934篇 |
专业分类
化学 | 172910篇 |
晶体学 | 5304篇 |
力学 | 20798篇 |
综合类 | 325篇 |
数学 | 50822篇 |
物理学 | 118697篇 |
出版年
2021年 | 4636篇 |
2020年 | 5141篇 |
2019年 | 5924篇 |
2018年 | 7912篇 |
2017年 | 7952篇 |
2016年 | 10042篇 |
2015年 | 5378篇 |
2014年 | 9265篇 |
2013年 | 15454篇 |
2012年 | 13759篇 |
2011年 | 15497篇 |
2010年 | 12763篇 |
2009年 | 12869篇 |
2008年 | 14346篇 |
2007年 | 13871篇 |
2006年 | 12519篇 |
2005年 | 10808篇 |
2004年 | 10264篇 |
2003年 | 9415篇 |
2002年 | 9741篇 |
2001年 | 9216篇 |
2000年 | 7293篇 |
1999年 | 5602篇 |
1998年 | 5283篇 |
1997年 | 4962篇 |
1996年 | 4568篇 |
1995年 | 4005篇 |
1994年 | 4099篇 |
1993年 | 4085篇 |
1992年 | 4002篇 |
1991年 | 4404篇 |
1990年 | 4387篇 |
1989年 | 4315篇 |
1988年 | 4032篇 |
1987年 | 4082篇 |
1986年 | 3747篇 |
1985年 | 4309篇 |
1984年 | 4515篇 |
1983年 | 3892篇 |
1982年 | 4058篇 |
1981年 | 3700篇 |
1980年 | 3456篇 |
1979年 | 3997篇 |
1978年 | 4075篇 |
1977年 | 4204篇 |
1976年 | 4362篇 |
1975年 | 4059篇 |
1974年 | 3963篇 |
1973年 | 4085篇 |
1972年 | 3544篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
In the present paper, Daubechies' wavelets and the computation of their scaling coefficients are briefly reviewed. Then a new method of computation is proposed. This method is based on the work [7] concerning a new orthonormality condition and relations among scaling moments, respectively. For filter lengths up to 16, the arising system can be explicitly solved with algebraic methods like Gröbner bases. Its simple structure allows one to find quickly all possible solutions. 相似文献
993.
Z. Kassai V. Koprda K. Bauerová M. Harangozó P. Bendová A. Bujnová A. Kassai 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(3):669-672
The composition and the permeation properties of the skin are dependent on age. In the animal models for permation studies, age affects the mechanical as well as the permeation properties significantly. The time dependence of permeation of 147Pm3+ from aqueous solution was established by the animal skin model and the age dependence of promethium permeation through the skin was examined. The aim was to find the optimum rat skin age model for radionuclide permeation studies and to assess the relative importance of the main permeation pathways: transepidermal and transfollicular permeation. The skin from 5-day-old rats (5DR) was found to represent the optimum animal model to study transepidermal permeation of ions. The skin from 9-day-old rats (9DR) was selected to study transfollicular permeation of ions. Comparison of the permeated amounts of promethium through the skin without hairs (3 DR to 6 DR) and with hairs (7DR to 12DR) showed that the additional permation mode via follicles significantly contributed to the permeation rate and extent. 相似文献
994.
L.G. Casado I. García T. Csendes V.G. Ruíz 《Journal of Optimization Theory and Applications》2003,118(1):27-43
Based on the investigation carried out in Ref. 1, this paper incorporates new studies about the properties of inclusion functions on subintervals while a branch-and-bound algorithm is solving global optimization problems. It is found that the relative place of the global minimum value within the inclusion function value of the objective function at the current interval indicates mostly whether the given interval is close to a minimizer point. This information is used in a heuristic interval rejection rule that can save a considerable amount of computation. Illustrative examples are discussed and an extended numerical study shows the advantages of the new approach. 相似文献
995.
996.
I. V. Bodnar 《Technical Physics》2003,48(5):587-591
The thermal expansion coefficients and the thermal conductivity of Bridgman-grown crystals of CuGa1−x
InxTe2 solid solutions are investigated. It is found that the thermal expansion coefficient varies with x linearly, while the thermal conductivity is minimal when x=0.5. The Debye temperature and the rms dynamic atomic displacements are calculated from experimental data. It is shown that
the Debye temperature decreases and the rms displacements in the crystal lattice sharply increase as the In content in the
solid solutions grows. 相似文献
997.
998.
A Stability Estimate for a Solution to a Three-Dimensional Inverse Problem for the Maxwell Equations
We consider the problem of determining dielectric permittivity and conductivity in the Maxwell equations. As additional information we prescribe the traces of the tangential components of the electromagnetic field on the lateral surface of a cylindric domain. We establish a stability estimate for a solution to the inverse problem and a uniqueness theorem. 相似文献
999.
V. V. Struzhanov V. V. Bashurov 《Journal of Applied Mechanics and Technical Physics》2003,44(4):549-556
Some iterative methods for calculating self-balanced stresses under shrinkage of a ball inclusion enclosed in a spherical matrix of a physically nonlinear damageable material. The stability of this system was studied using methods of catastrophe theory. It has been established that the beginning of divergence of the proposed iterative processes coincides with the moment of transition of the system to an unstable position of equilibrium. 相似文献
1000.
The Sobolev functional class on a finite disjoint union of segments is described in terms of the rate of polynomial approximation. Bibliography: 9 titles. 相似文献