全文获取类型
收费全文 | 78910篇 |
免费 | 372篇 |
国内免费 | 380篇 |
专业分类
化学 | 24467篇 |
晶体学 | 802篇 |
力学 | 6782篇 |
数学 | 32157篇 |
物理学 | 15454篇 |
出版年
2021年 | 37篇 |
2020年 | 35篇 |
2019年 | 39篇 |
2018年 | 10460篇 |
2017年 | 10276篇 |
2016年 | 6103篇 |
2015年 | 871篇 |
2014年 | 341篇 |
2013年 | 379篇 |
2012年 | 3836篇 |
2011年 | 10555篇 |
2010年 | 5689篇 |
2009年 | 6090篇 |
2008年 | 6616篇 |
2007年 | 8787篇 |
2006年 | 235篇 |
2005年 | 1325篇 |
2004年 | 1534篇 |
2003年 | 1980篇 |
2002年 | 1022篇 |
2001年 | 252篇 |
2000年 | 305篇 |
1999年 | 168篇 |
1998年 | 198篇 |
1997年 | 156篇 |
1996年 | 220篇 |
1995年 | 131篇 |
1994年 | 86篇 |
1993年 | 111篇 |
1992年 | 62篇 |
1991年 | 73篇 |
1990年 | 54篇 |
1989年 | 67篇 |
1988年 | 69篇 |
1987年 | 64篇 |
1986年 | 69篇 |
1985年 | 61篇 |
1984年 | 54篇 |
1983年 | 41篇 |
1982年 | 46篇 |
1981年 | 52篇 |
1980年 | 56篇 |
1979年 | 53篇 |
1978年 | 40篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
1907年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 875 毫秒
331.
In this paper we establish a sharp result concerning integral mean estimates for self-reciprocal polynomials. 相似文献
332.
333.
334.
335.
Olaf Steinbach 《Numerische Mathematik》2002,90(4):775-786
Summary. In this paper we investigate a stability estimate needed in hybrid finite and boundary element methods, especially in hybrid
coupled domain decomposition methods including mortar finite elements. This stability estimate is equivalent to the stability
of a generalized projection in certain Sobolev spaces. Using piecewise linear trial spaces and appropriate piecewise constant test spaces,
the stability of the generalized projection is proved assuming some mesh conditions locally.
Received April 11, 2000 / Revised version received February 15, 2001 / Published online July 25, 2001 相似文献
336.
337.
A well-known problem of prediction in linear regression models is to find a confidence interval for the random value of the dependent variable when the values of the independent variables are given. Such a situation may arise in economic quality control models when the independent variables are costly inputs and the dependent variable is some measure of quality or production. In such a circumstance, an important control objective may be to find values for the inputs that will maximize the lower limit of the prediction confidence interval for a fixed budget, or alternatively, to minimize the cost of the inputs for a fixed lower limit of the confidence interval. In this paper, we shall show that global optima can be found using known algorithms. The special case of simple linear regression is discussed and an illustrative example is provided. 相似文献
338.
In an integrated circuit (IC) packaging plant, the ink-marking machine has a significantly higher throughput than the other processing machines. When periodic demand surges result in backlog orders or in lost customers, there is a need to increase system throughput. To resolve this problem, the purchase of a new machine often results in excess capacity in addition to added operation and acquisition costs. Therefore, the productivity improvement effort has priority over the machine purchase decision. This paper seeks to optimize both throughput and cycle time performance for IC ink-marking machines. While throughput increase is the primary objective, there is an acceptable cycle time limit for a feasible solution. It is a multi-objective problem. The proposed solution methodology constructed a simulation metamodel for the ink-marking operation by using a fractional factorial experimental design and regression analysis. It is then solved by a hybrid response surface method and lexicographical goal programming approach. Solution results illustrated a successful application. 相似文献
339.
Julie Clutterbuck Oliver C. Schnürer Felix Schulze 《Calculus of Variations and Partial Differential Equations》2007,29(3):281-293
We prove stability of rotationally symmetric translating solutions to mean curvature flow. For initial data that converge
spatially at infinity to such a soliton, we obtain convergence for large times to that soliton without imposing any decay
rates.
The authors are members of SFB 647/B3 “Raum – Zeit – Materie: Singularity Structure, Long-time Behaviour and Dynamics of Solutions
of Non-linear Evolution Equations”. 相似文献
340.
In the core of the seminal Graph Minor Theory of Robertson and Seymour lies a powerful theorem capturing the ``rough' structure
of graphs excluding a fixed minor. This result was used to prove Wagner's Conjecture that finite graphs are well-quasi-ordered
under the graph minor relation. Recently, a number of beautiful results that use this structural result have appeared. Some
of these along with some other recent advances on graph minors are surveyed.
Research partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research, Grant number
16740044, by Sumitomo Foundation, by C & C Foundation and by Inoue Research Award for Young Scientists
Supported in part by the Research Grant P1–0297 and by the CRC program
On leave from: IMFM & FMF, Department of Mathematics, University of Ljubljana, Ljubljana, Slovenia 相似文献