全文获取类型
收费全文 | 21891篇 |
免费 | 482篇 |
国内免费 | 522篇 |
专业分类
化学 | 4382篇 |
晶体学 | 944篇 |
力学 | 396篇 |
综合类 | 58篇 |
数学 | 13161篇 |
物理学 | 3954篇 |
出版年
2023年 | 69篇 |
2022年 | 211篇 |
2021年 | 174篇 |
2020年 | 176篇 |
2019年 | 435篇 |
2018年 | 447篇 |
2017年 | 302篇 |
2016年 | 347篇 |
2015年 | 343篇 |
2014年 | 664篇 |
2013年 | 1506篇 |
2012年 | 556篇 |
2011年 | 1702篇 |
2010年 | 1510篇 |
2009年 | 1410篇 |
2008年 | 1509篇 |
2007年 | 1514篇 |
2006年 | 1150篇 |
2005年 | 980篇 |
2004年 | 852篇 |
2003年 | 657篇 |
2002年 | 683篇 |
2001年 | 443篇 |
2000年 | 433篇 |
1999年 | 391篇 |
1998年 | 405篇 |
1997年 | 307篇 |
1996年 | 383篇 |
1995年 | 365篇 |
1994年 | 354篇 |
1993年 | 269篇 |
1992年 | 272篇 |
1991年 | 196篇 |
1990年 | 187篇 |
1989年 | 176篇 |
1988年 | 109篇 |
1987年 | 134篇 |
1986年 | 90篇 |
1985年 | 164篇 |
1984年 | 117篇 |
1983年 | 70篇 |
1982年 | 96篇 |
1981年 | 123篇 |
1980年 | 109篇 |
1979年 | 67篇 |
1978年 | 112篇 |
1977年 | 94篇 |
1976年 | 90篇 |
1975年 | 40篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
We study the Besov regularity of conformal mappings for domains with rough boundary based on the well-posedness for the Dirichlet problem with Besov data. Also, sharp invertibility results for the classical layer potential operators on Sobolev-Besov spaces on the boundary of curvilinear polygons are obtained. 相似文献
132.
A recent conjecture of Myerson and Sander concerns divisibility properties of certain multinomial coefficients. We obtain results in this direction by further pursuing a line of attack developed earlier by the first author. 相似文献
133.
Our aim in this article is to prove the existence and the uniqueness of a global solution to a nonisothermal Ginzburg-Landau (Allen-Cahn) system. This system is obtained by considering, in addition to the fundamental laws of thermodynamics, a balance law for internal microforces proposed by M. Gurtin. 相似文献
134.
Antal Járai 《Aequationes Mathematicae》2003,65(3):236-266
Summary. We prove that - under certain conditions - measurable solutions $f$ of the functional equation $f(x)=h(x,y,f(g_{1}(x,y)),\ldots,f(g_{n}(x,y))),\quad(x,y)\in D \subset \mathbb{R}^{s} \times \mathbb{R}^{l}$ are continuous, even if $1\le l\le s$. As a tool we introduce new classes of functions which - roughly speaking - interpolate between continuous and Lebesgue measurable functions. Connection between these classes are also investigated. 相似文献
135.
R. Ochoa-Land?&#x;n M. Flores-Acosta R. Ram?&#x;rez-Bon H. Arizpe-Chávez F.F. Castillón-Barraza 《Journal of Physics and Chemistry of Solids》2003,64(11):2245-2251
CdS clusters were synthesized in A type zeolite by reaction in alkaline aqueous solution at temperatures from 30 to 70 °C. The optical properties of the samples were studied by diffuse reflectance and photoluminescence spectroscopy. Their crystalline structure and morphology were studied by X-ray diffraction and by transmission and scanning electron microscopy. We found that at lower temperatures the CdS clusters are encapsulated in the zeolite cages. We compared the properties of these clusters with those encapsulated in the cages of zeolites X and Y, prepared by similar methods. CdS clusters smaller than the CdS exciton diameter are also formed outside the cages in the zeolite matrix. The size of these clusters increases with temperature producing a red-shift of the absorption edge in the optical absorption spectra. 相似文献
136.
Chung-Cherng Lin 《Journal of Physics and Chemistry of Solids》2004,65(5):913-921
The phase transition of a synthetic clinoenstatite in a diamond-anvil cell has been studied by using Raman spectroscopy at various pressures and room temperature. The phenomena observed in clinoenstatite have been compared with that observed in orthoenstatite. It is found that the pressure-induced phase transitions in the two enstatites are reversible, but with different transition pressures and transition behavior. An analysis of Raman spectra has revealed that the two enstatites have different high-pressure polymorphs. This result suggests that the space group of the high-pressure polymorph of orthoenstatite is not of C2/c, and that orthoenstatite and orthoferrosilite have different transition routes at room temperature and high pressure. The compressional behavior of the high-PC2/c enstatite is also discussed according to the pressure dependences of Raman frequencies. 相似文献
137.
David F. Anderson 《Journal of Pure and Applied Algebra》2003,180(3):221-241
For a commutative ring R with set of zero-divisors Z(R), the zero-divisor graph of R is Γ(R)=Z(R)−{0}, with distinct vertices x and y adjacent if and only if xy=0. In this paper, we show that Γ(T(R)) and Γ(R) are isomorphic as graphs, where T(R) is the total quotient ring of R, and that Γ(R) is uniquely complemented if and only if either T(R) is von Neumann regular or Γ(R) is a star graph. We also investigate which cardinal numbers can arise as orders of equivalence classes (related to annihilator conditions) in a von Neumann regular ring. 相似文献
138.
The aim of this note is to generalize and apply results on matrix continued fractions representing the solution of discrete matrix Riccati equations. Assuming uniform bounds for the norm of the matrix coefficients of the continued fraction, the minimal and maximal solutions of the corresponding algebraic Riccati equation can be accurately enclosed. 相似文献
139.
Harm Derksen 《Advances in Mathematics》2004,185(2):207-214
Suppose that G is a linearly reductive group. Good degree bounds for generators of invariant rings were given in (Proc. Amer. Math. Soc. 129 (4) (2001) 955). Here we study minimal free resolutions of invariant rings. For finite linearly reductive groups G it was recently shown in (Adv. Math. 156 (1) (2000) 23, Electron Res. Announc. Amer. Math. Soc. 7 (2001) 5, Adv. Math. 172 (2002) 151) that rings of invariants are generated in degree at most the group order |G|. In characteristic 0 this degree bound is a classical result by Emmy Noether (see Math. Ann. 77 (1916) 89). Given an invariant ring of a finite linearly reductive group G, we prove that the ideal of relations of a minimal set of generators is generated in degree at most ?2|G|. 相似文献
140.
A ring is said to be a left essential extension of a reduced ring (domain) if it contains a left ideal which is a reduced ring (domain) and intersects nontrivially every nonzero twosided ideal of the ring. We prove that every ring which is a left essential extension of a reduced ring is a subdirect sum of rings which are essential extensions of domains, but the converse implication does not hold. We give some applications of this result and discuss several related questions.Received: 6 January 2003 相似文献