全文获取类型
收费全文 | 295295篇 |
免费 | 3272篇 |
国内免费 | 1688篇 |
专业分类
化学 | 145395篇 |
晶体学 | 3971篇 |
力学 | 15435篇 |
综合类 | 61篇 |
数学 | 55389篇 |
物理学 | 80004篇 |
出版年
2020年 | 1751篇 |
2019年 | 1887篇 |
2018年 | 12619篇 |
2017年 | 12527篇 |
2016年 | 9533篇 |
2015年 | 3223篇 |
2014年 | 3801篇 |
2013年 | 9138篇 |
2012年 | 11258篇 |
2011年 | 19479篇 |
2010年 | 12045篇 |
2009年 | 12266篇 |
2008年 | 15088篇 |
2007年 | 17276篇 |
2006年 | 8553篇 |
2005年 | 8921篇 |
2004年 | 8316篇 |
2003年 | 7946篇 |
2002年 | 6936篇 |
2001年 | 6921篇 |
2000年 | 5329篇 |
1999年 | 3799篇 |
1998年 | 3211篇 |
1997年 | 3135篇 |
1996年 | 3203篇 |
1995年 | 2733篇 |
1994年 | 2791篇 |
1993年 | 2673篇 |
1992年 | 2879篇 |
1991年 | 2955篇 |
1990年 | 2751篇 |
1989年 | 2670篇 |
1988年 | 2615篇 |
1987年 | 2552篇 |
1986年 | 2575篇 |
1985年 | 3345篇 |
1984年 | 3401篇 |
1983年 | 2838篇 |
1982年 | 3088篇 |
1981年 | 2849篇 |
1980年 | 2650篇 |
1979年 | 2831篇 |
1978年 | 3031篇 |
1977年 | 3051篇 |
1976年 | 3075篇 |
1975年 | 2809篇 |
1974年 | 2918篇 |
1973年 | 2980篇 |
1972年 | 2334篇 |
1971年 | 1853篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
951.
952.
953.
954.
G. M. Maksimova A. L. Chuvilin E. M. Moroz V. A. Likholobov K. I. Matveev 《Kinetics and Catalysis》2004,45(6):870-878
Conditions for the preparation of stable aqueous monometallic and bimetallic colloidal solutions (sols) of noble metals (Ru, Rh, Pd, Pt, Ir, Ag, and Au) in the presence of polyoxometalates containing W, Mo, V, and Nb were found. The stability of sols against coagulation at room temperature was studied. The metal/C samples prepared by metal adsorption from sols were studied by powder X-ray diffraction analysis and transmission electron microscopy. The following factors of importance for the preparation of a stable sol are discussed: (1) the formation of a sol of a metal polyhydroxo complex stabilized by a polyoxometalate (preliminary stage) and (2) the formation of polyoxometalate-metal clusters in the course of reduction of polyhydroxo complexes.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 921–929.Original Russian Text Copyright © 2004 by Maksimova, Chuvilin, Moroz, Likholobov, Matveev. 相似文献
955.
956.
E. A. Bogdanov A. A. Kudryavtsev L. D. Tsendin R. R. Arslanbekov V. I. Kolobov V. V. Kudryavtsev 《Technical Physics》2003,48(9):1151-1158
Comprehensive self-consistent simulations of the positive column plasma of a dc oxygen discharge are performed with the help
of commercial CFDRC software (), which enables one to carry out computations in an arbitrary 3D geometry using fluid equations for heavy components and
a kinetic equation for electrons. The main scaling laws for the spatial distributions of charged particles are determined.
These scaling laws are found to be quite different in the parameter ranges that are dominated by different physical processes.
At low pressures, both the electrons and negative ions in the inner discharge region obey a Boltzmann distribution; as a result,
a flat profile of the electron density and a parabolic profile of the ion density are established there. In the ion balance,
transport processes prevail, so that ion heating in an electric field dramatically affects the spatial distribution of the
charged particles. At elevated pressures, the volume processes prevail in the balance of negative ions and the profiles of
the charged particle densities in the inner region turn out to be similar to each other. 相似文献
957.
Problem-structuring techniques are an integral aspect of ‘Soft-OR’. SSM, SAST, Strategic Choice, and JOURNEY Making, all depend for their success on a group developing a shared view of a problem through some form of explicit modelling. The negotiated problem structure becomes the basis for problem resolution. Implicit to this process is an assumption that members of the group share and build their knowledge about the problem domain. This paper explores the extent to which this assumption is reasonable. The research is based on detailed records from the use of JOURNEY Making, where it has used special purpose Group Support software to aid the group problem structuring. This software continuously tracks the contributions of each member of the group and thus the extent to which they appear to be ‘connecting’ and augmenting their own knowledge with that of other members of the group. Software records of problem resolution in real organisational settings are used to explore the sharing of knowledge among senior managers. These explorations suggest a typology of knowledge sharing. The implications of this typology for problem structuring and an agenda for future research are considered. 相似文献
958.
§ 1 IntroductionInthispaperwediscusstheglobalclassicalsolutionofamultidimensionalquasistationaryproblem .Theproblemcomesfromthediscussionofagrowthmodelofselfmaintainingprotocell(see [1— 3])inmultidimensionalcase .Theprotocellcanbevisualizedashavingaporousst… 相似文献
959.
Toshiyuki Sugawa 《Monatshefte für Mathematik》2003,139(1):61-68
The inner radius of univalence of a domain D with Poincaré density ρ
D
is the possible largest number σ such that the condition ∥ S
f
∥
D
= sup
w∈ D
ρ
D
(w)
−2∥ S
f
(z) ∥ ≤ σ implies univalence of f for a nonconstant meromorphic function f on D, where S
f
is the Schwarzian derivative of f. In this note, we give a lower bound of the inner radius of univalence for strongly starlike domains of order α in terms
of the order α.
The author was partially supported by the Ministry of Education, Grant-in-Aid for Encouragement of Young Scientists, 11740088.
A part of this work was carried out during his visit to the University of Helsinki under the exchange programme of scientists
between the Academy of Finland and the JSPS.
Received November 26, 2001; in revised form September 24, 2002
Published online May 9, 2003 相似文献
960.