全文获取类型
收费全文 | 747篇 |
免费 | 119篇 |
国内免费 | 82篇 |
专业分类
化学 | 168篇 |
晶体学 | 16篇 |
力学 | 85篇 |
综合类 | 9篇 |
数学 | 401篇 |
物理学 | 269篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 11篇 |
2020年 | 21篇 |
2019年 | 26篇 |
2018年 | 23篇 |
2017年 | 30篇 |
2016年 | 18篇 |
2015年 | 23篇 |
2014年 | 40篇 |
2013年 | 70篇 |
2012年 | 39篇 |
2011年 | 37篇 |
2010年 | 49篇 |
2009年 | 46篇 |
2008年 | 44篇 |
2007年 | 52篇 |
2006年 | 57篇 |
2005年 | 51篇 |
2004年 | 45篇 |
2003年 | 33篇 |
2002年 | 35篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 15篇 |
1998年 | 13篇 |
1997年 | 18篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有948条查询结果,搜索用时 0 毫秒
111.
Rafael Herná ndez Marí a J. Vá zquez-Gallo 《Transactions of the American Mathematical Society》2001,353(1):95-115
We determine the degree of some strata of singular cubic surfaces in the projective space . These strata are subvarieties of the parametrizing all cubic surfaces in . It is known what their dimension is and that they are irreducible. In 1986, D. F. Coray and I. Vainsencher computed the degree of the 4 strata consisting on cubic surfaces with a double line. To work out the case of isolated singularities we relate the problem with (stationary) multiple-point theory.
112.
In an earlier paper (see Proc. London Math. Soc. (3) 84 (2002)257288) we showed that an irreducible integral binarycubic form f(x, y) attains infinitely many prime values, providingthat it has no fixed prime divisor. We now extend this resultby showing that f(m, n) still attains infinitely many primevalues if m and n are restricted by arbitrary congruence conditions,providing that there is still no fixed prime divisor. Two immediate consequences for the solvability of diagonal cubicDiophantine equations are given. 2000 Mathematics Subject Classification11N32 (primary), 11N36, 11R44 (secondary). 相似文献
113.
Antonio Ros 《Journal of the American Mathematical Society》2004,17(2):373-388
Given a cubic space group (viewed as a finite group of isometries of the torus ), we obtain sharp isoperimetric inequalities for -invariant regions. These inequalities depend on the minimum number of points in an orbit of and on the largest Euler characteristic among nonspherical -symmetric surfaces minimizing the area under volume constraint (we also give explicit estimates of this second invariant for the various crystallographic cubic groups ). As an example, we prove that any surface dividing into two equal volumes with the same (orientation-preserving) symmetries as the A. Schoen minimal Gyroid has area at least (the conjectured minimizing surface in this case is the Gyroid itself whose area is ).
114.
115.
It is well known that a prime link diagram corresponds to a signed plane graph without cut vertices (Kauffman, 1989). In this paper, we present a new relation between prime links and cubic 3-polytopes. Let be the set of links such that each has a diagram whose corresponding signed plane graph is the graph of a cubic 3-polytope. We show that all nontrivial prime links, except -torus links and -pretzel links, can be obtained from by using some operation of untwining. Furthermore, we define the generalized cubic 3-polytope chains and then show that any nontrivial link can be obtained from by some untwining operations, where is the set of links corresponding to generalized cubic 3-polytope chains. These results are used to simplify the computation of the Kauffman brackets of links so that the computing can be done in a unified way for many infinite families of links.
116.
In this paper, we present a numerical method for solving a class of nonlinear, singularly perturbed two-point boundary-value problems with a boundary layer on the left end of the underlying interval. The original second-order problem is reduced to an asymptotically equivalent first-order problem and is solved by a numerical method using a fourth-order cubic spline in the inner region. The method has been analyzed for convergence and is shown to yield anO(h
4) approximation to the solution. Some test examples have been solved to demonstrate the efficiency of the method.The authors thank the referee for his helpful comments. 相似文献
117.
118.
A numerical method based on cubic splines with nonuniform grid is given for singularly-perturbed nonlinear two-point boundary-value problems. The original nonlinear equation is linearized using quasilinearization. Difference schemes are derived for the linear case using a variable-mesh cubic spline and are used to solve each linear equation obtained via quasilinearization. Second-order uniform convergence is achieved. Numerical examples are given in support of the theoretical results. 相似文献
119.
一类三次kolmogorov系统的极限环 总被引:1,自引:0,他引:1
本研究一类三次kolmogorov系统解的定性行为,给出了系统解的有界性与极限环存在性的充分条件。 相似文献
120.
For the planar Z
2-equivariant cubic systems having two elementary focuses, the characterization of a bi-center problem and shortened expressions
of the first six Liapunov constants are completely discussed. The necessary and sufficient conditions for the existence of
the bi-center are obtained. All possible first integrals are given. Under small Z
2-equivariant cubic perturbations, the conclusion that there exist at most 12 small-amplitude limit cycles with the scheme
〈6 ∐ 6〉 is proved. 相似文献