全文获取类型
收费全文 | 2119篇 |
免费 | 101篇 |
国内免费 | 15篇 |
专业分类
化学 | 1659篇 |
晶体学 | 36篇 |
力学 | 48篇 |
数学 | 117篇 |
物理学 | 375篇 |
出版年
2024年 | 15篇 |
2023年 | 20篇 |
2022年 | 130篇 |
2021年 | 112篇 |
2020年 | 69篇 |
2019年 | 79篇 |
2018年 | 97篇 |
2017年 | 73篇 |
2016年 | 102篇 |
2015年 | 68篇 |
2014年 | 75篇 |
2013年 | 158篇 |
2012年 | 174篇 |
2011年 | 158篇 |
2010年 | 102篇 |
2009年 | 89篇 |
2008年 | 112篇 |
2007年 | 91篇 |
2006年 | 73篇 |
2005年 | 55篇 |
2004年 | 48篇 |
2003年 | 32篇 |
2002年 | 58篇 |
2001年 | 34篇 |
2000年 | 39篇 |
1999年 | 12篇 |
1998年 | 18篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1974年 | 2篇 |
1937年 | 2篇 |
排序方式: 共有2235条查询结果,搜索用时 15 毫秒
1.
2.
LetP(z) be a polynomial of degreen which does not vanish in |z|<1. In this paper, we estimate the maximum and minimum moduli of thekth polar derivative ofP(z) on |z|=1 and thereby obtain compact generalizations of some known results, which among other results, yields interesting refinements of Erdos-Lax theorem and a theorem of Ankeny and Rivlin. 相似文献
3.
A mathematical model of laser beam treatment of double layer alloys (Ni/Fe, Al/Fe and Cr/Fe systems) describing the effect of laser beam on different physical and geometrical parameters of coated layer system has been adapted. The numerical solutions of the non-homogeneous heat-transport differential equation could estimate the temperature of the treated region.The suggested model allows investigation of the temperature distribution as a function of treated surface and laser parameters. The physical parameters of the treated materials were taken as functions of temperature due to the change in the temperature of the treated double layer materials. 相似文献
4.
In this paper we establish a sharp result concerning integral mean estimates for self-reciprocal polynomials. 相似文献
5.
The object of the present paper is to study quasi-conformally flat weakly Ricci symmetric manifolds.
相似文献
6.
Ashfaque H. Bokhari Abdul R. Kashif Asghar Qadir 《General Relativity and Gravitation》2003,35(6):1059-1076
Curvature collineations are symmetry directions for the Riemann tensor, as isometries are for the metric tensor and Ricci collineations are for the Ricci tensor. Complete listings of many metrics possessing some minimal symmetry have been given for a number of symmetry groups for the latter two symmetries. It is shown that a claimed complete listing of cylindrically symmetric static metrics by their curvature collineations [1] was actually incomplete and is completed here. It turns out that in this complete list, unlike the previous claim, there are curvature collineations that are distinct from the set of isometries and of Ricci collineations. The physical interpretation of some of the metrics obtained is given. 相似文献
7.
Dipak Ghosh Madhumita Lahiri Argha Deb Susobhan Das Krishnadas Purkait Biswanath Biswas Jayanta Roy Choudhury Rini Chatterjee Abdul Kayum Jafry 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):243-249
The scaled factorial moments and the multifractal moments have been investigated in differentη-intervals to study the dynamical fluctuation of pions produced in 200 AGeV32S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process. 相似文献
8.
Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells. 相似文献
9.
Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o287-o288
In the title compound, C18H13BrClNO3, the heterocyclic ring of the indole is distorted from planarity towards an envelope conformation. The orientations of the indole, oxetane, chloro and bromophenyl substituents are conditioned by the sp3 states of the spiro‐junction and the Cl‐attached C atoms. 相似文献
10.
Abdul Majid Jim Tunney Steve Argue Mike Post 《Journal of Sol-Gel Science and Technology》2004,32(1-3):323-326
We have investigated the synthesis of perovskite-type SrFeOx (2.5 x 3.0) using three preparative methods: sol-gel, mechanochemical processing and solid state reactions at high temperature of the corresponding oxides. The sample obtained after calcination of the gel from sol-gel method, contained the least amount of strontium carbonate impurity. The amount of strontium carbonate impurity decreased with the increase in calcination temperature. Perovskites obtained have been characterized by X-ray diffraction (XRD) and nitrogen adsorption isotherms. Samples obtained from three methods have been compared with respect to calcination temperature, crystallite size and specific surface area.Issued as NRCC No. 46479. 相似文献