全文获取类型
收费全文 | 36788篇 |
免费 | 3468篇 |
国内免费 | 2348篇 |
专业分类
化学 | 5868篇 |
晶体学 | 98篇 |
力学 | 5802篇 |
综合类 | 670篇 |
数学 | 21077篇 |
物理学 | 9089篇 |
出版年
2024年 | 61篇 |
2023年 | 335篇 |
2022年 | 520篇 |
2021年 | 674篇 |
2020年 | 936篇 |
2019年 | 887篇 |
2018年 | 900篇 |
2017年 | 1004篇 |
2016年 | 1092篇 |
2015年 | 908篇 |
2014年 | 1437篇 |
2013年 | 3036篇 |
2012年 | 1582篇 |
2011年 | 2058篇 |
2010年 | 1798篇 |
2009年 | 2338篇 |
2008年 | 2312篇 |
2007年 | 2213篇 |
2006年 | 2167篇 |
2005年 | 1673篇 |
2004年 | 1486篇 |
2003年 | 1507篇 |
2002年 | 1384篇 |
2001年 | 1188篇 |
2000年 | 1121篇 |
1999年 | 1036篇 |
1998年 | 868篇 |
1997年 | 793篇 |
1996年 | 665篇 |
1995年 | 502篇 |
1994年 | 451篇 |
1993年 | 391篇 |
1992年 | 372篇 |
1991年 | 276篇 |
1990年 | 251篇 |
1989年 | 194篇 |
1988年 | 188篇 |
1987年 | 164篇 |
1986年 | 100篇 |
1985年 | 213篇 |
1984年 | 252篇 |
1983年 | 128篇 |
1982年 | 213篇 |
1981年 | 187篇 |
1980年 | 133篇 |
1979年 | 157篇 |
1978年 | 141篇 |
1977年 | 92篇 |
1976年 | 65篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
52.
Cai Xiaochun 《Annals of Differential Equations》2006,22(1):1-6
In this paper, we apply a critical point theorem and obtain the condition for the existence of three solutions to two-point boundary value problem of a second order nonlinear difference equation. 相似文献
53.
Papert's (1978) appeal to reconsider the power and possibilities of the aesthetic in mathematics learning is often ignored in mathematics education research. This paper begins with the premise, put forth by Dewey (1934), that the aesthetic structures many dimensions of inquiry and experience. In the same way that using particular paintings, musical compositions, or even everyday experiences has been instrumental to attempts by philosophers to understand the aesthetic dimensions of meaning and experience in artistic domains, I propose that analysing a particular encounter with mathematics may help reveal the nature and role of the often nebulous responses of elegance, beauty, and `fit' to which mathematicians lay claim in their mathematical activity. To achieve this, I draw on and adapt the defining features of the aesthetic character of experience set forth by the aesthetician Beardsley (1982). This, in turn, sheds light on the role thataesthetics can play in mathematical inquiry and experience, and provides initial categories and conjectures that can be used to investigate the potential roles of aesthetics in mathematics learning contexts.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
54.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
55.
56.
57.
本文利用聚集型状态方程,克拉贝龙方程以及临界条件推出聚集活性参量方程.分析结果表明,医药的药理活性是可以用聚集活性参量予以定量表征.本文给出了某些医药的主要的药物成分,如氧化亚氮 乙醚、氯仿和水杨酸甲酯等嘛醉剂),一氧化氮(硝酸甘油)、乙醇胺(医药活性剂)和多巴胺(神经递质)的生物活性数据.实践经验表明,这些化学品分别在生命体的心血管系统、神经系统和免疫系统中起着重要的药理功能作用.这表明,本文研究的内容在医药学研究领域有其重要意义. 相似文献
58.
Johannes Elschner Rainer Hinder Gunther Schmidt 《Advances in Computational Mathematics》2002,16(2-3):139-156
This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R
2 coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis. 相似文献
59.
关于惠斯登电桥测电阻倍率与检流计灵敏度关系的研究 总被引:1,自引:0,他引:1
在相同的设备条件下,电桥临近平衡时灵敏度最高的最佳倍率是:组成倍率的两个电阻的数量级与待测电阻数量级相等,且比值为1的倍率。 相似文献
60.
Summary Considered here are model equations for weakly nonlinear and dispersive long waves, which feature general forms of dispersion and pure power nonlinearity. Two variants of such equations are introduced, one of Korteweg-de Vries type and one of regularized long-wave type. It is proven that solutions of the pure initial-value problem for these two types of model equations are the same, to within the order of accuracy attributable to either, on the long time scale during which nonlinear and dispersive effects may accumulate to make an order-one relative difference to the wave profiles.This research was supported in part by the National Science Foundation. A considerable portion of the project was completed while the first author was resident at the Institute for Mathematics and Its Applications, University of Minnesota. 相似文献