全文获取类型
收费全文 | 122980篇 |
免费 | 6466篇 |
国内免费 | 5562篇 |
专业分类
化学 | 43773篇 |
晶体学 | 1092篇 |
力学 | 8490篇 |
综合类 | 305篇 |
数学 | 34839篇 |
物理学 | 25718篇 |
综合类 | 20791篇 |
出版年
2024年 | 173篇 |
2023年 | 781篇 |
2022年 | 1353篇 |
2021年 | 1450篇 |
2020年 | 1457篇 |
2019年 | 1228篇 |
2018年 | 11566篇 |
2017年 | 11436篇 |
2016年 | 7713篇 |
2015年 | 2643篇 |
2014年 | 2479篇 |
2013年 | 2981篇 |
2012年 | 6944篇 |
2011年 | 14091篇 |
2010年 | 8465篇 |
2009年 | 8595篇 |
2008年 | 9488篇 |
2007年 | 11508篇 |
2006年 | 2494篇 |
2005年 | 3331篇 |
2004年 | 3250篇 |
2003年 | 3488篇 |
2002年 | 2669篇 |
2001年 | 1681篇 |
2000年 | 1498篇 |
1999年 | 1516篇 |
1998年 | 1247篇 |
1997年 | 1174篇 |
1996年 | 1174篇 |
1995年 | 908篇 |
1994年 | 873篇 |
1993年 | 730篇 |
1992年 | 672篇 |
1991年 | 569篇 |
1990年 | 520篇 |
1989年 | 443篇 |
1988年 | 408篇 |
1987年 | 287篇 |
1986年 | 221篇 |
1985年 | 155篇 |
1984年 | 93篇 |
1983年 | 89篇 |
1982年 | 64篇 |
1981年 | 65篇 |
1980年 | 58篇 |
1979年 | 49篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
本论文选用Apple-Ⅱ作主机,开发了一套外设接口扩展箱和相应的应用软件,用于实现在钢厂中对六台单轧机的热轧钢板长度在线检测和现场显示,同时对钢板的长度按照合格、超长、超短进行分类统计,打印生产报表。此外还提供随时修改钢板长度(标尺)设定值和随机查询各台轧机产质量状况的功能。在接口扩展箱中,采用了包括光电耦合在内的若干抗干扰措施,保证系统能在钢厂恶劣环境中正常运行。本系统已在工厂轧机上试用成功。 相似文献
53.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
54.
Gaston Casanova 《Advances in Applied Clifford Algebras》2004,14(2):249-252
We define analytic functions within Clifford Algebras CL, and study their trigonometric properties. We write the addition formulas when their arguments, A and B in CL, commute, this generalizes ordinary trigonometry. We examine in particular the case A2 = 1.
相似文献
55.
M. Lashkarizadeh Bami 《Semigroup Forum》2004,69(2):219-229
In the present paper it is shown that if S1 and S2 are two
Clifford topological semigroups satisfying certain conditions
and T is an isometric isomorphism of LUC(S1*) onto LUC(S2*), then T
maps S1 topologically isomorphically onto S2. Furthermore, T
maps M
l
n(S1) (M(S1), respectively) isometrically
isomorphically onto M
l
n(S2) (M(S2), respectively). Indeed,
we have obtained a generalization of a well-known result of
Ghahramani, Lau and Losert for locally compact groups to a more
general setting of Clifford topological semigroups. 相似文献
56.
ZHU Yabin ZHOU Yueliang LIU Zhen WANG Shufang CHEN Zhenghao U Huibin YANG Guozhen XlAO Ling Ren Hongtao JIAO Yulei Zheng Minghui 《中国科学G辑(英文版)》2004,47(2):165-172
The irreversibility field (Hirr) of Y-based superconductor is much higher than that of Bi-based superconductor. Y-based superconductor is capable of maintaining stable electrical currents in high magnetic field and electric field, so it is a better suited mate-rial for electric-current applications. Commonly, the Y-based tapes comprise a YBCO thick film deposited on a flexible substrate, typically with an intermediate buffer layer, and an overcoat of noble metal. In this process, the interm… 相似文献
57.
Hong-Xing Zheng Dao-Yin Yu 《International Journal of Infrared and Millimeter Waves》2005,26(9):1343-1353
In this paper, a very useful numerical technique has been developed for analyzing the transient characteristics of a planar-spiral inductor on-chip. A locally conformal technique and an alternating-direction implicit scheme are applied to the finite-difference time-domain method. A formulation for solving three dimensional Maxwell’s equations is proposed. Using the proposed method, various parameters of the planar-spiral inductors have been analyzed and an equivalent circuit, which includes frequency-independent circuit elements, has been introduced. Highly computational efficiency is implemented. Numerical results show excellent agreement with the measured data over a wide frequency range. 相似文献
58.
Andrew Barton 《The Journal of the Operational Research Society》1987,38(10):965-974
This paper describes some work carried out in the Scientific Research and Development Branch (SRDB) of the Home Office, intended to contribute to an overall aim of building up internal expertise in the field of expert systems. This was done by carrying out a number of pilot and demonstrator projects, two of which are described in some detail. The plan, which proved successful, was to build as far as possible on the relevant skills already possessed by an OR group in the branch. The lessons learned from these are summarized in the hope that they will be of use to other groups who wish to become involved in this important area. 相似文献
59.
60.
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