全文获取类型
收费全文 | 54828篇 |
免费 | 1627篇 |
国内免费 | 202篇 |
专业分类
化学 | 31077篇 |
晶体学 | 366篇 |
力学 | 1373篇 |
综合类 | 6篇 |
数学 | 9050篇 |
物理学 | 14785篇 |
出版年
2021年 | 380篇 |
2020年 | 577篇 |
2019年 | 491篇 |
2018年 | 581篇 |
2017年 | 558篇 |
2016年 | 1262篇 |
2015年 | 983篇 |
2014年 | 1159篇 |
2013年 | 2420篇 |
2012年 | 2105篇 |
2011年 | 2302篇 |
2010年 | 1592篇 |
2009年 | 1427篇 |
2008年 | 2183篇 |
2007年 | 2055篇 |
2006年 | 2037篇 |
2005年 | 1847篇 |
2004年 | 1612篇 |
2003年 | 1414篇 |
2002年 | 1315篇 |
2001年 | 1163篇 |
2000年 | 976篇 |
1999年 | 759篇 |
1998年 | 694篇 |
1997年 | 702篇 |
1996年 | 816篇 |
1995年 | 738篇 |
1994年 | 754篇 |
1993年 | 775篇 |
1992年 | 809篇 |
1991年 | 646篇 |
1990年 | 643篇 |
1989年 | 603篇 |
1988年 | 594篇 |
1987年 | 604篇 |
1986年 | 551篇 |
1985年 | 853篇 |
1984年 | 808篇 |
1983年 | 612篇 |
1982年 | 695篇 |
1981年 | 664篇 |
1980年 | 698篇 |
1979年 | 673篇 |
1978年 | 691篇 |
1977年 | 708篇 |
1976年 | 628篇 |
1975年 | 593篇 |
1974年 | 547篇 |
1973年 | 522篇 |
1962年 | 337篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
121.
We extend the previously found accelerated Kerr-Schild metrics for Einstein-Maxwell-null dust and Einstein-Born-Infeld-null dust equations to the cases including the cosmological constant. This way we obtain the generalization of the charged de Sitter metrics in static space-times. We also give a generalization of the zero acceleration limit of our previous Einstein-Maxwell and Einstein-Born-Infeld solutions. 相似文献
122.
The Kα to Lα and Kβ to Lβ intensity ratios of seven elements have been measured following photoionization at 59.5 keV by using a Si (Li) detector
(FWHM=155 eV at 5.96 keV). The intensity ratios were determined by measuring K and L x-rays emitted from a standard target of a given element. The theoretical values of the Kα to Lα and Kβ to Lβ intensity ratios were calculated using theoretically tabulated values of shell/subshell photoionization cross sections,
fluorescence yields, Coster-Kronig transition probabilities, and radiative decay rates for ηKLi≠ and ηKLi=0. The measured values are in good agreement with theoretical results.
From Optika i Spektroskopiya, Vol. 97, No. 2, 2004, pp. 186–189.
Original English Text Copyright ? 2004 by A. Kü?ük?nder, S?ğüt, E. Kü?ük?nder, Büyükkasap.
This article was submitted by the authors in English. 相似文献
123.
124.
Günter F. Steinke 《Journal of Geometry》2007,87(1-2):160-178
125.
The growth mechanism of the peritectic η phase involving the peritectic reaction and peritectic transformation in Cu-70%Sn alloy was investigated under directional
solidification. The results show that a major growth mechanism in thickening of the peritectic η-layer is not the peritectic reaction but the peritectic transformation. The transformation temperature and isothermal time
play crucial roles in determining the volume fraction and the thickness of the peritectic η phase. With the increase of the temperature and isothermal time, the volume fraction of the peritectic η phase increases. The regressed data show that the relationship between the thickness of η phase (Δx) and the transformation temperature (T) meets the following equation In Δx=6.5−1673 1 / T. Additionally, there exists a relationship between the thickness of the η phase (Δx) and the isothermal time (t) at the 9 mm solidification distance below the peritectic reaction interface, Δx=0.72t
1/2, which is consistent with the theoretical model.
Supported by the National Science Foundation of China (Grant No. 50395102) 相似文献
126.
Alvaro P. Raposo Hans J. Weber David E. Alvarez-Castillo Mariana Kirchbach 《Central European Journal of Physics》2007,5(3):253-284
We briefly review the five possible real polynomial solutions of hypergeometric differential equations. Three of them are
the well known classical orthogonal polynomials, but the other two are different with respect to their orthogonality properties.
We then focus on the family of polynomials which exhibits a finite orthogonality. This family, to be referred to as the Romanovski
polynomials, is required in exact solutions of several physics problems ranging from quantum mechanics and quark physics to
random matrix theory. It appears timely to draw attention to it by the present study. Our survey also includes several new
observations on the orthogonality properties of the Romanovski polynomials and new developments from their Rodrigues formula. 相似文献
127.
K. -J. Berg A. Berger H. Hofmeister 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):309-311
Small spherical silver particles in a surface layer of commercial flat glass were produced by means of sodium-silver ion exchange. In each volume element of the layer there is a Gaussian distribution of the particle diameters. The mean diameter increases with penetration depth. Within one individual sample it can vary from 4.5 nm immediately at the glass surface up to more than 50 nm at the end of the layer. Due to a special preparation technique the results were gained by microspectrophotometric measurements as well as by investigations carried out with the transmission electron microscope and the electron-probe microanalyzer on one and the same sample always as function of the penetration depth. 相似文献
128.
Hamid Olia Erich Russi Hans Thomann 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1992,43(3):581-583
Summary An atomizer had been designed that could create an aerosol of a liquid with high viscosity. The amount of additional driving gas that had to be used was very low. In a cooperation with the University Hospital in Zurich the atomizer was miniaturized and used for treating six patients. 相似文献
129.
130.
Idealization of a decomposition theorem 总被引:1,自引:1,他引:0
In 1986, Tong [13] proved that a function f : (X,τ)→(Y,φ) is continuous if and only if it is α-continuous and A-continuous. We extend this decomposition of continuity in terms of ideals. First, we introduce the notions of regular-I-closed sets, A
I-sets and A
I -continuous functions in ideal topological spaces and investigate their properties. Then, we show that a function f : (X,τ,I)→(Y, φ) is continuous if and only if it is α-I-continuous and A
I-continuous.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献