全文获取类型
收费全文 | 4017篇 |
免费 | 412篇 |
国内免费 | 387篇 |
专业分类
化学 | 616篇 |
晶体学 | 7篇 |
力学 | 225篇 |
综合类 | 62篇 |
数学 | 2715篇 |
物理学 | 1191篇 |
出版年
2024年 | 3篇 |
2023年 | 38篇 |
2022年 | 68篇 |
2021年 | 83篇 |
2020年 | 108篇 |
2019年 | 95篇 |
2018年 | 106篇 |
2017年 | 111篇 |
2016年 | 132篇 |
2015年 | 101篇 |
2014年 | 195篇 |
2013年 | 331篇 |
2012年 | 188篇 |
2011年 | 229篇 |
2010年 | 213篇 |
2009年 | 232篇 |
2008年 | 321篇 |
2007年 | 265篇 |
2006年 | 240篇 |
2005年 | 217篇 |
2004年 | 189篇 |
2003年 | 183篇 |
2002年 | 198篇 |
2001年 | 137篇 |
2000年 | 119篇 |
1999年 | 126篇 |
1998年 | 112篇 |
1997年 | 89篇 |
1996年 | 75篇 |
1995年 | 56篇 |
1994年 | 43篇 |
1993年 | 26篇 |
1992年 | 24篇 |
1991年 | 12篇 |
1990年 | 26篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1936年 | 2篇 |
排序方式: 共有4816条查询结果,搜索用时 31 毫秒
91.
92.
Andrew Fiore 《Numerical Functional Analysis & Optimization》2013,34(6):679-690
Our goal is to demonstrate the utility of the calculus of moving surfaces (CMS) in boundary variation problems. We discuss the relative advantages of the CMS compared to the alternative approach of interior variations. We illustrate the technique by calculating the two leading terms of a power series for the Laplace eigenvalues on an ellipse with semi-axes 1 + a and 1 + b, where a and b are small. We compare the CMS estimates with those obtained by the conventional finite element method with Richardson extrapolation. The comparison confirms the cubic rate of convergence for the CMS estimates. 相似文献
93.
Yuan Chen Lulu Fu Baobao Sun Cheng Qian Dr. Srikala Pangannaya Hong Zhu Prof. Jing Ma Prof. Juli Jiang Dr. Zhigang Ni Prof. Ruibing Wang Prof. Xiancai Lu Prof. Leyong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):5890-5896
Chiral α-amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α-amino acids has mainly focused on the determination of l /d enantiomers. Herein, selection of planar chiral conformations between water-soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α-side chain or ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α-side chain and ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α-carbon of a chiral α-amino acid molecule. 相似文献
94.
95.
96.
Scattering neutrons are one of the key factors that may affect the images of fast neutron radiog- raphy. In this paper, a mathematical model for scattered neutrons is developed on a cylinder sample, and an empirical formula for scattered neutrons is obtained. According to the results given by Monte Carlo methods, the parameters in the empirical formula are obtained with curve fitting, which confirms the logicality of the empirical formula. The curve-fitted parameters of common materials such as <'6>LiD are given. 相似文献
97.
《复变函数与椭圆型方程》2012,57(15):1163-1164
Let X be a smooth and connected Riemann surface of genus g 0 and f: X P1, h: X P1 non-constant meromorphic functions on X. Fix an integer n 4 and assume the existence of n distinct points a1, , an P1 such that [image omitted] (set-theoretically) for every i. Here we prove that either f = h or [image omitted]. 相似文献
98.
99.
《Optimization》2012,61(8):1009-1028
Bilevel convex models are studied after being cast into a parametric programming form. This form has a lexicographic inner-outer structure where the optimal value of the outer model is optimized on the set of optimal solutions of the inner model. Optimal solutions are characterized using a Lagrangian saddle-point approach and a marginal value formula is given for the outer model. These are used to formulate a general method for finding an optimal solution by input optimization. 相似文献
100.