全文获取类型
收费全文 | 12000篇 |
免费 | 1458篇 |
国内免费 | 962篇 |
专业分类
化学 | 3316篇 |
晶体学 | 117篇 |
力学 | 626篇 |
综合类 | 297篇 |
数学 | 2723篇 |
物理学 | 7341篇 |
出版年
2024年 | 17篇 |
2023年 | 72篇 |
2022年 | 343篇 |
2021年 | 342篇 |
2020年 | 267篇 |
2019年 | 287篇 |
2018年 | 320篇 |
2017年 | 451篇 |
2016年 | 498篇 |
2015年 | 463篇 |
2014年 | 765篇 |
2013年 | 1081篇 |
2012年 | 692篇 |
2011年 | 756篇 |
2010年 | 618篇 |
2009年 | 759篇 |
2008年 | 789篇 |
2007年 | 805篇 |
2006年 | 685篇 |
2005年 | 557篇 |
2004年 | 509篇 |
2003年 | 467篇 |
2002年 | 441篇 |
2001年 | 316篇 |
2000年 | 271篇 |
1999年 | 268篇 |
1998年 | 237篇 |
1997年 | 238篇 |
1996年 | 177篇 |
1995年 | 152篇 |
1994年 | 122篇 |
1993年 | 98篇 |
1992年 | 89篇 |
1991年 | 65篇 |
1990年 | 53篇 |
1989年 | 53篇 |
1988年 | 97篇 |
1987年 | 44篇 |
1986年 | 26篇 |
1985年 | 28篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 21篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1972年 | 2篇 |
1959年 | 6篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Based on scalar diffraction theory, 8-phase-level 256×256 elements diffractive microlens array with element dimension of 50×33 μm2 have been fabricated on the back-side of PtSi(3~5 μm) infrared CCD. The measurement results indicated that the ratio of the signal-to-noise of the infrared CCD with microlens was increased by a factor of 2.8. 相似文献
42.
43.
A new microtensile tester for the study of MEMS materials with the aid of atomic force microscopy 总被引:4,自引:0,他引:4
An apparatus has been designed and implemented to measure the elastic tensile properties (Young's modulus and tensile strength)
of surface micromachined polysilicon specimens. The tensile specimens are “dog-bone” shaped ending in a large “paddle” for
convenient electrostatic or, in the improved apparatus, ultraviolet (UV) light curable adhesive gripping deposited with electrostatically
controlled manipulation. The typical test section of the specimens is 400 μm long with 2 μm×50 μm cross section. The new device
supports a nanomechanics method developed in our laboratory to acquire surface topologies of deforming specimens by means
of Atomic Force Microscopy (AFM) to determine (fields of) strains via Digital Image Correlation (DIC). With this tool, high
strength or non-linearly behaving materials can be tested under different environmental conditions by measuring the strains
directly on the surface of the film with nanometer resolution. 相似文献
44.
On a nonlinear multigrid algorithm with primal relaxation for the image total variation minimisation
Digital image restoration has drawn much attention in the recent years and a lot of research has been done on effective variational partial differential equation models and their theoretical studies. However there remains an urgent need to develop fast and robust iterative solvers, as the underlying problem sizes are large. This paper proposes a fast multigrid method using primal relaxations. The basic primal relaxation is known to get stuck at a ‘local’ non-stationary minimum of the solution, which is usually believed to be ‘non-smooth’. Our idea is to utilize coarse level corrections, overcoming the deadlock of a basic primal relaxation scheme. A further refinement is to allow non-regular coarse levels to correct the solution, which helps to improve the multilevel method. Numerical experiments on both 1D and 2D images are presented. 相似文献
45.
本文介绍非线性方程转化直线性方程和多元线性回归法来分析近代物理实验中塞曼效应分裂干涉圆环多处选点测量的处理过程。 相似文献
46.
47.
Hidefumi Ohsugi 《Journal of Combinatorial Theory, Series A》2006,113(4):718-725
Athanasiadis [Ehrhart polynomials, simplicial polytopes, magic squares and a conjecture of Stanley, J. Reine Angew. Math., to appear.] studies an effective technique to show that Gorenstein sequences coming from compressed polytopes are unimodal. In the present paper we will use such the technique to find a rich class of Gorenstein toric rings with unimodal h-vectors arising from finite graphs. 相似文献
48.
用区域分解算法结合蒙特卡罗法求坦克温度场和红外辐射出射度 总被引:3,自引:0,他引:3
本文将区域分解算法和蒙特卡罗法相结合,求坦克温度场和红外辐射出射度.采用蒙特卡罗法计算辐射传递系数,可以考虑界面的复杂辐射特性,如:镜反射、各向异性发射、各向异性反射等;可直接考虑界面的复杂几何特性,如:相互遮挡、太阳入射方向上的投影面积等.引入辐射传递系数,分离了计算的难点,使得在时间域(计算步骤)上能把整个问题分解为若干个子问题并行处理、在空间域(计算区域)上将坦克分解为若干个子区域,缩小计算规模,并可使用多个处理器并行计算;同时减轻了蒙特卡罗法编程的难度,缩短了计算时间. 相似文献
49.
§ 1 IntroductionA triple system of order v and indexλ,denoted by TS(v,λ) ,is a collection of3- ele-mentsubsets Aof a v- set X,so thatevery 2 - subsetof X appears in preciselyλ subsets of A.L etλ≥ 2 and (X,A) be a TS(v,λ) .If Acan be partitioned into t(≥ 2 ) parts A1,A2 ,...,Atsuch that each (X,Ai) is a TS(v,λi) for 1≤ i≤ t,then (X,A) is called de-composable.Otherwise it is indecomposable.If t=λ,λi=1for 1≤ i≤ t,the TS(v,λ) (X,A) is called completely decomposable.It … 相似文献
50.