全文获取类型
收费全文 | 60325篇 |
免费 | 4370篇 |
国内免费 | 2493篇 |
专业分类
化学 | 35057篇 |
晶体学 | 849篇 |
力学 | 3093篇 |
综合类 | 111篇 |
数学 | 6462篇 |
物理学 | 21616篇 |
出版年
2023年 | 554篇 |
2022年 | 805篇 |
2021年 | 1106篇 |
2020年 | 1306篇 |
2019年 | 1284篇 |
2018年 | 1297篇 |
2017年 | 1142篇 |
2016年 | 1847篇 |
2015年 | 1501篇 |
2014年 | 1987篇 |
2013年 | 3292篇 |
2012年 | 3778篇 |
2011年 | 4167篇 |
2010年 | 2855篇 |
2009年 | 2783篇 |
2008年 | 3114篇 |
2007年 | 2952篇 |
2006年 | 2690篇 |
2005年 | 2315篇 |
2004年 | 1937篇 |
2003年 | 1614篇 |
2002年 | 1528篇 |
2001年 | 1747篇 |
2000年 | 1382篇 |
1999年 | 1285篇 |
1998年 | 1015篇 |
1997年 | 1004篇 |
1996年 | 944篇 |
1995年 | 822篇 |
1994年 | 738篇 |
1993年 | 617篇 |
1992年 | 689篇 |
1991年 | 654篇 |
1990年 | 613篇 |
1989年 | 552篇 |
1988年 | 524篇 |
1987年 | 524篇 |
1986年 | 454篇 |
1985年 | 512篇 |
1984年 | 507篇 |
1983年 | 379篇 |
1982年 | 416篇 |
1981年 | 389篇 |
1980年 | 322篇 |
1979年 | 403篇 |
1978年 | 381篇 |
1977年 | 395篇 |
1976年 | 398篇 |
1975年 | 350篇 |
1973年 | 336篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Due to avoiding the inherent escrow of identity-based cryptography and yet not requiring certificates to guarantee the authenticity of public keys, certificateless public key cryptography has received a significant attention. Due to various applications of bilinear pairings in cryptography, numerous pairing-based encryption schemes, signature schemes, and other cryptographic primitives have been proposed. In this paper, a new certificateless signature scheme based on bilinear pairings is presented. The signing algorithm of the proposed scheme is very simple and does not require any pairing computation. Combining our signature scheme with certificateless public key cryptography yields a complete solution of certificateless public key system. As an application of the proposed signature scheme, a certificateless proxy signature scheme is also presented. We analyze both schemes from security point of view.__________Published in Lietuvos Matematikos Rinkinys, Vol. 45, No. 1, pp. 95–103, January–March, 2005. 相似文献
102.
I. A. Uspenskaya Z. S. Vakhovskaya M. M. Efremova M. L. Kovba A. L. Emelina Zh. V. Dobrokhotova Yu. V. Goryushkina L. A. Tiflova A. A. Popova A. S. Monaenkova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(4):529-534
The thermodynamic properties of the Ln2BaO4 phases (Ln = Dy, Ho, Sm) were studied by the electromotive force method with a fluoride electrolyte (890–1180 K), solution calorimetry in 1.07 N hydrochloric acid at 298.15 K, and differential scanning calorimetry (298–860 K). The experimental data were jointly processed, and the thermodynamic functions of the compounds over the temperature range 298–1200 K were calculated. 相似文献
103.
Mo2Ni3Si/NiSi metal silicide composite coatings with a fine microstructure consisting of Mo2Ni3Si primary dendrites and the interdendritic Mo2Ni3Si/NiSi eutectics were fabricated on austenitic stainless steel AISI 321 by laser cladding process. Small amplitude reciprocating sliding wear resistance of the coatings is evaluated as functions of normal load and slip amplitude and the wear mechanisms were discussed based on worn surface morphology observations. Results showed that the Mo2Ni3Si/NiSi coatings have excellent small amplitude reciprocating sliding wear resistance. 相似文献
104.
The inhomogeneous Dirichlet problems concerning divergence form elliptic equations are studied. Optimal regularity requirements on the coefficients and domains for the W1,p theory, 1 < p < ∞, are obtained. The principal coefficients are supposed to be in the John‐Nirenberg space with small BMO seminorms. The domain is a Reifenberg domain. These conditions for the W1,p theory not only weaken the requirements on the coefficients but also lead to a more general geometric condition on the domains. In fact, these domains might have fractal dimensions. © 2004 Wiley Periodicals, Inc. 相似文献
105.
The first α‐diimine nickel(I) complex having a chloro bridge is reported. The centrosymmetric dinuclear structure of {[ArN?C(Me)C(Me)?NAr]NiCl}2[Ar?2,6?C6H3(i‐Pr)2] features two chelating α‐diimine ligands and two bridged chlorine atoms, so that a distorted tetrahedral N2Cl2 coordination geometry for nickel results. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
106.
Z. Karaoglanov 《Fresenius' Journal of Analytical Chemistry》1941,121(5-6):190-209
Ohne Zusammenfassung 相似文献
107.
A. Sanusi M. Z. A. Yahya S. Navaratnam W. J. Basirun Y. Alias N. S. Mohamed A. K. Arof 《Ionics》2003,9(3-4):253-257
In this study, lead sulphide (PbS) was prepared by the chemical bath deposition technique. The sample was characterized by
X-ray diffraction (XRD), Energy Dispersive Analysis of X-rays (EDAX) and cyclic voltammetry. EDAX spectrum shows peaks attributable
to lead and sulphur. The EDAX analysis also shows that the prepared sample is stoichiometric. Cyclic voltammetry experiments
were recorded at 100 mV·s−1 and 400 mV·s−1 scan rates. Results show that the rate controlling electrochemical reaction is electron transfer. The presence of redox waves
shows that the lithium intercalation and deintercalation can occur as a result of lattice expansion in PbS. There were no
differences in the PbS XRD data before and after the cyclic voltammetry experiments indicating that the PbS structure is not
modified upon lithium ion intercalation and deintercalation in PbS. The discharge characteristics for 35 cycles of the cell
using the LiCoO2/PbS couple is presented indicating the possible development of such materials as anode in lithium ion cells. 相似文献
108.
109.
Zhang Xinliang Huang Dexiu Sun Junqiang Liu Deming 《Optical and Quantum Electronics》2004,36(7):627-634
A simple scheme for single to multi-channel wavelength conversion based on cross-gain modulation of amplified spontaneous emission (ASE) spectrum in semiconductor optical amplifier (SOA) is described. Single to 16-channel wavelength conversion at 10 Gb/s is first demonstrated without any additional probe lights, the modulation information carried by input signal could be converted into arbitrary many channels if only the demultiplexer with enough channels is exploited. Output performance and pattern effects are investigated experimentally. 相似文献
110.