全文获取类型
收费全文 | 1806篇 |
免费 | 48篇 |
国内免费 | 7篇 |
专业分类
化学 | 1379篇 |
晶体学 | 23篇 |
力学 | 16篇 |
数学 | 88篇 |
物理学 | 355篇 |
出版年
2023年 | 5篇 |
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 30篇 |
2019年 | 36篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 31篇 |
2015年 | 34篇 |
2014年 | 39篇 |
2013年 | 112篇 |
2012年 | 80篇 |
2011年 | 104篇 |
2010年 | 43篇 |
2009年 | 64篇 |
2008年 | 105篇 |
2007年 | 100篇 |
2006年 | 94篇 |
2005年 | 109篇 |
2004年 | 112篇 |
2003年 | 105篇 |
2002年 | 85篇 |
2001年 | 59篇 |
2000年 | 45篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 26篇 |
1996年 | 28篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 23篇 |
1992年 | 17篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 11篇 |
排序方式: 共有1861条查询结果,搜索用时 0 毫秒
1.
Hirokazu Nishimura 《International Journal of Theoretical Physics》1995,34(2):211-228
The notion of a manual, introduced and investigated in detail by Foulis, Randall, and their followers, has turned out to be further reaching than its originators had envisaged. Its omnipresence is comparable with the notion of a sheaf, whose significance is well recognized by every pure and applied mathematician. The principal concern of this paper is to give an appropriate vehicle, as general as possible, by which the theory of manuals can be developed. The vehicle is called an orthogonal category, which is akin to the notion of a category with coproducts. Orthogonal categories provide also a new perspective on the notion of a sheaf over a complete Boolean algebra, deepening our comprehension of Boolean mathematics and paving the way to quantum mathematics. 相似文献
2.
3.
4.
5.
Hiroshi Sakamoto 《Journal of Discrete Algorithms》2005,3(2-4):416-430
A linear-time approximation algorithm for the grammar-based compression is presented. This is an optimization problem to minimize the size of a context-free grammar deriving a given string. For each string of length n, the algorithm guarantees approximation ratio without suffix tree construction. 相似文献
6.
Kazuhiro Kurata Masataka Shibata Shigeru Sakamoto 《Applied Mathematics and Optimization》2004,50(3):259-278
Let $\Omega$ be a bounded domain in ${\bf R^n}$ with Lipschitz
boundary,
$\lambda >0,$ and $1\le p \le (n+2)/(n-2)$ if $n\ge 3$ and $1\le p< +\infty$
if $n=1,2$. Let $D$ be a measurable subset of $\Omega$ which belongs
to the class
$
{\cal C}_{\beta}=\{D\subset \Omega \quad | \quad |D|=\beta\}
$
for the prescribed $\beta\in (0, |\Omega|).$
For any $D\in{\cal C}_{\beta}$, it is well known that
there exists a unique
global minimizer $u\in H^1_0(\Omega)$, which we denote by
$u_D$, of the functional
\[\quad
J_{\Omega,D}(v)=\frac12\int_{\Omega}|\nabla v|^2\,
dx+\frac{\lambda}{p+1}\int_{\Omega}|v|^{p+1}\, dx
-\int_{\Omega}\chi_Dv\,dx
\]
on $H^1_0(\Omega)$.
We consider the optimization problem
$
E_{\beta,\Omega}=\inf_{D\in {\cal C}_{\beta}} J_D(u_D)
$
and say that
a subset $D^*\in {\cal C}_{\beta}$ which attains
$E_{\beta,\Omega}$
is an optimal configuration to this problem.
In this paper we show the existence, uniqueness
and non-uniqueness, and
symmetry-preserving and symmetry-breaking phenomena of the
optimal configuration $D^*$ to this
optimization problem in various settings. 相似文献
7.
8.
Hirokazu Tezuka 《Zeitschrift fur Physik C Particles and Fields》1995,65(1):101-104
It is shown that the Dirac equation with attractive monomial vector potential cannot confine a particle. General polynomial type vector potential cannot confine a particle, either. This condition is not changed by a scalar potential smaller than the vector one. 相似文献
9.
Oishi S Kamano T Niida A Odagaki Y Hamanaka N Yamamoto M Ajito K Tamamura H Otaka A Fujii N 《The Journal of organic chemistry》2002,67(17):6162-6173
Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres corresponding to dipeptides having one N-methylamino acid, and application to bioactive peptides, are described. In a key reaction introducing the chiral alpha-alkyl group of the isosteres, organocopper-mediated alkylation of syn-beta-methylated gamma-mesyloxy-alpha,beta-enoate 26a afforded E- and Z-isomers of anti-S(N)2' products in a solvent-dependent manner. The resulting two isosteres, D-Phe-psi[(E)-CH=CMe]-L-Val 27a and D-Phe-psi[(Z)-CH=CMe]-L-Val 28b, which corresponded to trans- and cis-conformers of D-Phe-L-MeVal, respectively, were utilized in a structure-activity relationship study on cyclic RGD peptides 1 and 2, in company with a psi[(E)-CH=CH]-type alkene dipeptide isostere, D-Phe-psi[(E)-CH=CH]-L-Val. The cyclic isostere-containing pseudopeptides 3, 4, and 40 were synthesized and biological activity against integrin alpha(V)beta(3) and alpha(IIb)beta(3) receptors were also evaluated. 相似文献
10.
T Tatee K Narita S Kurashige S Ito H Miyazaki H Yamanaka M Mizugaki T Sakamoto H Fukuda 《Chemical & pharmaceutical bulletin》1986,34(4):1643-1655