全文获取类型
收费全文 | 765篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
化学 | 402篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 61篇 |
物理学 | 306篇 |
出版年
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 22篇 |
2011年 | 37篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 38篇 |
2007年 | 19篇 |
2006年 | 26篇 |
2005年 | 29篇 |
2004年 | 23篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 22篇 |
2000年 | 20篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 18篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 31篇 |
1992年 | 27篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 21篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 6篇 |
1977年 | 19篇 |
1976年 | 16篇 |
1975年 | 12篇 |
1974年 | 7篇 |
1973年 | 13篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1969年 | 7篇 |
1968年 | 4篇 |
排序方式: 共有775条查询结果,搜索用时 7 毫秒
71.
Tracy E. Scott Amin Khalili Brandon Newton Robert Warren Daniel P. Browe Joseph W. Freeman 《先进技术聚合物》2019,30(10):2604-2612
Hydrogels have been used for many applications in tissue engineering and regenerative medicine due to their versatile material properties and similarities to the native extracellular matrix. Poly (ethylene glycol) diacrylate (PEGDA) is an ionic electroactive polymer (EAP), a material that responds to an electric field with a change in size or shape while in an ionic solution, that may be used in the development of hydrogels. In this study, we have investigated a positively charged EAP that can bend without the need of external ions. PEGDA was modified with the positively charged molecule 2‐(methacryloyloxy)ethyl‐trimethylammonium chloride (MAETAC) to provide its own positive ions. This hydrogel was then characterized and optimized for bending and cellular biocompatibility with C2C12 mouse myoblast cells. Studies show that the polymer responds to an electric field and supports C2C12 viability. 相似文献
72.
73.
74.
75.
76.
77.
R.M. Freeman F. Haas M.-P. Nicoli A. Morsad Z. Basrak 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):239-244
It has been noticed that a distinct resemblance exists at large angles among angular distributions measured for reaction
channels at the energies of some resonance-like structures in the 12C+12C and 14C+16O systems. It is pointed out that such forms are typical of a diffraction pattern of a broad band of coherent partial waves.
Received: 5 October 1998 / Revised version: 8 December 1998 相似文献
78.
New algorithms for parallel one-dimensional globally adaptive quadrature are developed. The algorithms are implemented on
a Kendall Square Research KSR-1 parallel computer and numerical results are presented. The most successful algorithm gives
significant speedups on a range of hard problems, including ones with singular integrands.
Both authors acknowledge the support of the EEC Esprit Basic Research Action Programme, Project 6634 (APPARC).
The second author acknowledges the support of the NATO Collaborative Research Grant 920037. 相似文献
79.
Helmut Sengstschmid Heinz Sterk Ray Freeman 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,131(2):315-326
An automated scheme is described which locates the centers of cross peaks in two-dimensional correlation spectra, even under conditions of severe overlap. Double-quantum-filtered correlation (DQ-COSY) spectra have been investigated, but the method is also applicable to TOCSY and NOESY spectra. The search criterion is the intrinsic symmetry (or antisymmetry) of cross-peak multiplets. An initial global search provides the preliminary information to build up a two-dimensional “chemical shift grid.” All genuine cross peaks must be centered at intersections of this grid, a fact that reduces the extent of the subsequent search program enormously. The program recognizes cross peaks by examining the symmetry of signals in a test zone centered at a grid intersection. This “symmetry filter” employs a “lowest value algorithm” to discriminate against overlapping responses from adjacent multiplets. A progressive multiplet subtraction scheme provides further suppression of overlap effects. The processed two-dimensional correlation spectrum represents cross peaks as points at the chemical shift coordinates, with some indication of their relative intensities. Alternatively, the information is presented in the form of a correlation table. The authenticity of a given cross peak is judged by a set of “confidence criteria” expressed as numerical parameters. Experimental results are presented for the 400-MHz double-quantum-filtered COSY spectrum of 4-androsten-3,17-dione, a case where there is severe overlap. 相似文献
80.
We prove that the variance of the error function in the shifted circle problem, as a function of the shift, is a continuous function which has a sharp local maximum with infinite derivatives at every rational point on a plane. 相似文献