全文获取类型
收费全文 | 24506篇 |
免费 | 3770篇 |
国内免费 | 2641篇 |
专业分类
化学 | 17015篇 |
晶体学 | 303篇 |
力学 | 1452篇 |
综合类 | 239篇 |
数学 | 2672篇 |
物理学 | 9236篇 |
出版年
2024年 | 78篇 |
2023年 | 504篇 |
2022年 | 819篇 |
2021年 | 878篇 |
2020年 | 984篇 |
2019年 | 905篇 |
2018年 | 755篇 |
2017年 | 734篇 |
2016年 | 1105篇 |
2015年 | 1044篇 |
2014年 | 1301篇 |
2013年 | 1678篇 |
2012年 | 2083篇 |
2011年 | 2086篇 |
2010年 | 1434篇 |
2009年 | 1387篇 |
2008年 | 1543篇 |
2007年 | 1427篇 |
2006年 | 1357篇 |
2005年 | 1101篇 |
2004年 | 885篇 |
2003年 | 724篇 |
2002年 | 628篇 |
2001年 | 526篇 |
2000年 | 522篇 |
1999年 | 590篇 |
1998年 | 487篇 |
1997年 | 428篇 |
1996年 | 436篇 |
1995年 | 387篇 |
1994年 | 358篇 |
1993年 | 326篇 |
1992年 | 271篇 |
1991年 | 233篇 |
1990年 | 235篇 |
1989年 | 160篇 |
1988年 | 119篇 |
1987年 | 84篇 |
1986年 | 97篇 |
1985年 | 65篇 |
1984年 | 37篇 |
1983年 | 39篇 |
1982年 | 37篇 |
1981年 | 21篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1976年 | 1篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Meifang Zhu 《Applied Physics A: Materials Science & Processing》1991,52(5):285-288
A theoretical analysis of thermostimulated conductivity spectra TSC(T) has been applied to determine the density of gap states g(E) in a-Si: H and a-Si: H/a-SiN
x
: H multilayer structures. The results for g(E) are consistent with the results deduced from Fritzsche's analytical approach as well as other methods. A comparison has been made between the two different analytical approaches for TSC(T). We discuss the relationship between the energy of maximum thermostimulated current emission E
m and quasi-Fermi level E
q. We demonstrate that E
q could be a better parameter than E
m in the general theoretical treatment of thermostimulated conductivity. 相似文献
142.
143.
Fulton R Jensen T Johnson DR Kagan H Kass R Morrow F Whitmore J Wilson P Bortoletto D Chen W Dominick J McIlwain RL Miller DH Ng CR Schaffner SF Shibata EI Shipsey IP Yao W Battle M Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Sharma V Skwarnicki T Thulasidas M Zhu G Csorna SE Letson T Alexander J Artuso M Bebek C Berkelman K Browder T Cassel DG Cheu E Coffman DM Crawford G DeWire JW 《Physical review D: Particles and fields》1991,43(3):651-663
144.
145.
Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Skwarnicki T Stone S Thusalidas M Yao W Zhu G Barnes AV Bartelt J 《Physical review D: Particles and fields》1991,44(3):593-600
146.
This paper is a continuation of the research carried out in [1]–[2], where the robustness analysis for stochastic approximation algorithms is given for two cases: 1. The regression function and the Liapunov function are not zero at the sought-forx
0; 2. lim sup
n
a131n
i=1
n
i+1 is not zero, where {
i
} are the measurement errors and {a
n} are the weighting coefficients in the algorithm. Allowing these deviations from zero to occur simultaneously but to remain small, this paper shows that the estimation error is still small even for a class of measurement errors more general than that considered in [2].This project is supported by the National Natural Science Foundation of China. 相似文献
147.
J. Zhu 《Mathematical Methods of Operations Research》1992,36(4):359-377
We present a primal-dual path following interior algorithm for a class of linearly constrained convex programming problems with non-negative decision variables. We introduce the definition of a Scaled Lipschitz Condition and show that if the objective function satisfies the Scaled Lipschitz Condition then, at each iteration, our algorithm reduces the duality gap by at least a factor of (1–/n), where is positive and depends on the curvature of the objective function, by means of solving a system of linear equations which requires no more than O(n3) arithmetic operations. The class of functions having the Scaled Lipschitz Condition includes linear, convex quadratic and entropy functions. 相似文献
148.
149.
150.
C, N, O, F, Cl, and Br red and infrared laser emission was investigated using hollow cathode discharges in gas mixtures of helium and molecules containing the corresponding atoms. A total of 33 laser lines with wavelengths from 0.7 to 2.0m was observed. Three laser lines of atomic C, five laser lines of atomic N, two laser lines of atomic Cl and five laser lines of atomic Br were observed for the first time. Dissociation charge transfer and dissociative excitation transfer are suggested as being responsible for populating the upper laser levels. 相似文献