全文获取类型
收费全文 | 223572篇 |
免费 | 1739篇 |
国内免费 | 678篇 |
专业分类
化学 | 122883篇 |
晶体学 | 3344篇 |
力学 | 8596篇 |
综合类 | 6篇 |
数学 | 24659篇 |
物理学 | 66501篇 |
出版年
2020年 | 2057篇 |
2019年 | 2347篇 |
2018年 | 3260篇 |
2017年 | 3178篇 |
2016年 | 4423篇 |
2015年 | 2489篇 |
2014年 | 3972篇 |
2013年 | 9621篇 |
2012年 | 7267篇 |
2011年 | 8916篇 |
2010年 | 6325篇 |
2009年 | 6117篇 |
2008年 | 8512篇 |
2007年 | 8615篇 |
2006年 | 8052篇 |
2005年 | 7318篇 |
2004年 | 6481篇 |
2003年 | 5941篇 |
2002年 | 5755篇 |
2001年 | 6083篇 |
2000年 | 4836篇 |
1999年 | 3553篇 |
1998年 | 3084篇 |
1997年 | 3123篇 |
1996年 | 2959篇 |
1995年 | 2414篇 |
1994年 | 2541篇 |
1993年 | 2574篇 |
1992年 | 2691篇 |
1991年 | 2771篇 |
1990年 | 2661篇 |
1989年 | 2636篇 |
1988年 | 2547篇 |
1987年 | 2514篇 |
1986年 | 2427篇 |
1985年 | 3174篇 |
1984年 | 3317篇 |
1983年 | 2630篇 |
1982年 | 2951篇 |
1981年 | 2807篇 |
1980年 | 2606篇 |
1979年 | 2814篇 |
1978年 | 2939篇 |
1977年 | 2950篇 |
1976年 | 2921篇 |
1975年 | 2773篇 |
1974年 | 2755篇 |
1973年 | 2930篇 |
1972年 | 1921篇 |
1967年 | 1858篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
251.
252.
E. V. Suchilkina 《Journal of Mathematical Sciences》2007,147(1):6510-6516
At the end of the twentieth century, in mathematical physics, the Knizhnik-Zamolodchikov equations for the root systems A
n
and their generalizations for the root systems of types B
n
, C
n
, and D were constructed. For the root system of type G
2, the vector version of the Knizhnik-Zamolodchikov equations was obtained by M. P. Zamakhovskii and V. P. Leksin. However,
the tensor version of these equations has remained unstudied. In this paper, the Knizhnik-Zamolodchikov equations associated
with the root system of type G
2 are considered.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 38, Suzdal
Conference-2004, Part 3, 2006. 相似文献
253.
254.
A nonlinear pulse systems with a time-variant continuous linear part is considered. A method for synthesizing an output-feedback robust stabilizing control is suggested. 相似文献
255.
Microstructure and oxygen stoichiometry of YBaCuO films manufactured by laser ablation are investigated. Dependence of the specific electrical resistivity and superconducting
parameters of films on microstructure and oxygen stoichiometry is demonstrated. Conditions of deposition are determined, under
which films with minimum microstructure defects and good conducting properties are formed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 41–45, February, 2007. 相似文献
256.
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
257.
This paper reports a successful achievement of laser-induced biological cell fusion using an excimer laser excited dye laser. To our knowledge, we examined for the first time the dependence of fusion rate on laser pulse energy, number of laser pulses, and laser wavelength. Maximum fusion rate of approximately 50% was obtained by this laser fusion technology. 相似文献
258.
Investigation of anode and cathode jets influence on electric arc properties with current up to 500 kA 总被引:1,自引:0,他引:1
Rutberg P.G. Bogomaz A.A. Budin A.V. Kolikov V.A. Pinchuk M.E. Pozubenkov A.A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(2):201-206
A number of phenomena connected with the formation of electrode jets in discharges in hydrogen at a current of 10/sup 5/-10/sup 6/ A, a current growth rate of 10/sup 10/ A/s, an initial pressure 0.1-4.0 MPa, and a discharge gap length of 5-40 mm were studied. After the secondary breakdown, the jets are observed through a discharge semitransparent channel, widening with velocity (4-7) /spl middot/ 10/sup 2/ m/s. Shockwave formation was detected at the interaction of jets with the surrounding gas and the opposite electrode. Plasma vapor pressure of metal near the end of the tungsten cathode 70 /spl mu/s after initiation of a discharge was 180 MPa. Thus, magnitude of brightness temperature was 59 /spl middot/ 10/sup 3/ K, with an average charge of ions-m~=3.1, and a concentration of metal vapors n=5.3/spl middot/10/sup 19/ cm/sup -3/. While those at the end of the anode 90 /spl mu/s after initiation of discharge: m~=2.6, n=7.4/spl middot/10/sup 19/ cm/sup -3/. Probable reasons of high-voltage drops near the electrodes (the summarized magnitude of which is /spl sim/1 kV) are discussed on the basis of experimental data. For the first time, the shadow method registered symmetric ejection of material from the all-cathode surface the maximum discharge current was observed. 相似文献
259.
A column generation (CG) approach for the solution of timetabling problems is presented. This methodology could be used for various instances of the timetabling problem, although in this paper the solution of the high-school situation in Greece is presented. The results obtained show clearly that the CG approach that has been extremely successful in recent years in the solution of airline crew scheduling problems could also be very efficient and robust for the solution of timetabling problems. Several large timetabling problems corresponding to real problems have been successfully solved, with the solutions obtained feasible and of very high quality in accordance with the problem definition. In addition, none of the solutions contained any idle hour for any of the teachers, which was one of the main goals of this optimization effort. 相似文献
260.
A. Yu. Kolesov E. F. Mishchenko N. Kh. Rozov 《Proceedings of the Steklov Institute of Mathematics》2007,259(1):101-127
We carry out a detailed analysis of the existence, asymptotics, and stability problems for periodic solutions that bifurcate
from the zero equilibrium state in systems with large delay. The account is based on a specific meaningful example given by
a certain scalar nonlinear second-order differential-difference equation that is a mathematical model of a single-circuit
RCL oscillator with delay in a feedback loop. 相似文献