全文获取类型
收费全文 | 9786篇 |
免费 | 924篇 |
国内免费 | 726篇 |
专业分类
化学 | 7059篇 |
晶体学 | 155篇 |
力学 | 275篇 |
综合类 | 65篇 |
数学 | 1468篇 |
物理学 | 2414篇 |
出版年
2023年 | 101篇 |
2022年 | 161篇 |
2021年 | 215篇 |
2020年 | 267篇 |
2019年 | 234篇 |
2018年 | 213篇 |
2017年 | 220篇 |
2016年 | 328篇 |
2015年 | 324篇 |
2014年 | 350篇 |
2013年 | 527篇 |
2012年 | 683篇 |
2011年 | 692篇 |
2010年 | 512篇 |
2009年 | 514篇 |
2008年 | 618篇 |
2007年 | 506篇 |
2006年 | 500篇 |
2005年 | 426篇 |
2004年 | 366篇 |
2003年 | 319篇 |
2002年 | 347篇 |
2001年 | 241篇 |
2000年 | 184篇 |
1999年 | 163篇 |
1998年 | 122篇 |
1997年 | 114篇 |
1996年 | 130篇 |
1995年 | 106篇 |
1994年 | 113篇 |
1993年 | 95篇 |
1992年 | 91篇 |
1991年 | 99篇 |
1990年 | 81篇 |
1989年 | 66篇 |
1988年 | 68篇 |
1987年 | 63篇 |
1986年 | 77篇 |
1985年 | 93篇 |
1984年 | 104篇 |
1983年 | 61篇 |
1982年 | 81篇 |
1981年 | 90篇 |
1980年 | 76篇 |
1979年 | 67篇 |
1978年 | 78篇 |
1977年 | 51篇 |
1976年 | 69篇 |
1975年 | 55篇 |
1973年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Epithelial cell layers on soft elastic substrates or pillar arrays are commonly used as model systems for investigating the role of force in tissue growth, maintenance, and repair. Here we show analytically that the experimentally observed localization of traction forces to the periphery of the cell layers does not necessarily imply increased local cell activity, but follows naturally from the elastic problem of a finite-sized contractile layer coupled to an elastic foundation. For homogeneous contractility, the force localization is determined by one dimensionless parameter interpolating between linear and exponential force profiles for the extreme cases of very soft and very stiff substrates, respectively. If contractility is sufficiently increased at the periphery, outward directed displacements can occur at intermediate positions. We also show that anisotropic extracellular stiffness can lead to force localization in the stiffer direction, as observed experimentally. 相似文献
172.
173.
174.
175.
A. Lunk P. Bachem P. Scheible L. Ulrich 《Applied Physics A: Materials Science & Processing》2001,72(5):557-564
The development of in situ diagnostics of the most important species and reactions in the plasma and/or on the surface during
thin-film growth is one of the current topics in plasma-enhanced vapor deposition. In situ thin film diagnostic methods which
could be used in plasma processing are restricted due to the presence of electrons and ions. The advantages and disadvantages
of different applicable methods will be discussed. The spectroscopic in situ control of boron nitride film growth is presented
as an example of surface modification in low-temperature, low-pressure plasma processing. The growth of cubic and hexagonal
boron nitride is observed by polarized infrared reflection spectroscopy in absorption and ellipsometric configurations as
well as by single-wavelength ellipsometry in the visible spectral range. Modeling of the experimental results gives detailed
information on growth conditions and internal stress of the films.
Received: 8 August 2000 / Accepted: 12 December 2000 / Published online: 3 April 2001 相似文献
176.
GUO Han-Ying LI Yu-Qi WU Ke 《理论物理通讯》2001,(7)
We present the symplectic algorithm in the Lagrangian formalism for the Hamiltonian systems by virtue of the noncommutative differential calculus with respect to the discrete time and the Euler-Lagrange cohomological concepts. We also show that the trapezoidal integrator is symplectic in certain sense.`` 相似文献
177.
Coleman自同构群的投射极限 总被引:2,自引:0,他引:2
在这篇注记中,利用群的投射极限性质给出了有限可解群的Coleman自同构群的一个具体构造.作为应用,证明了二面体群的Coleman外自同构群或者是1或者是一个初等阿贝尔2-群. 相似文献
178.
Summary In a recent paper [11], two of the authors investigated a fast reduction method for solving difference equations which approximate certain boundary value problems for Poisson's equation. In this second paper, we prove the numerical stability of the reduction method, and also report on further developments of the method. For the general case, the provided bounds for the numerical errors behave roughly like the condition numberO(n
2) of the linear system; for more realistic model problems estimates of order less thanO(n) are obtained (n
–1=h=mesh width). The number of operations required for the reduction method isO(n
2
), for the usual five-point difference formula, as well as for the common nine-point formula with discretization error of orderh
4. 相似文献
179.
Let k be a commutative ring, GG finite affine algebraic k-groups, and HH the dual Hopfalgebras of the affine algebras of G resp. G. The main results of this paper are: (I) If k is semilocal (e.g. k a field) there is an H-linear, HH-colinear, unitary, augmented isomorphism HHH H, where HH is the coalgebra belonging to G/G. (II) If the k-submodule of the fixelements of (HH)* is isomorphic to k (e.g. k principal or semilocal), then HH is a Frobeniusextension of the second kind. 相似文献
180.
Ulrich Christian 《Mathematische Annalen》1959,138(5):363-397
Ohne Zusammenfassung 相似文献