全文获取类型
收费全文 | 5609篇 |
免费 | 853篇 |
国内免费 | 506篇 |
专业分类
化学 | 2291篇 |
晶体学 | 102篇 |
力学 | 1042篇 |
综合类 | 140篇 |
数学 | 875篇 |
物理学 | 2518篇 |
出版年
2024年 | 8篇 |
2023年 | 60篇 |
2022年 | 133篇 |
2021年 | 140篇 |
2020年 | 203篇 |
2019年 | 156篇 |
2018年 | 146篇 |
2017年 | 181篇 |
2016年 | 249篇 |
2015年 | 201篇 |
2014年 | 232篇 |
2013年 | 453篇 |
2012年 | 252篇 |
2011年 | 258篇 |
2010年 | 205篇 |
2009年 | 274篇 |
2008年 | 312篇 |
2007年 | 348篇 |
2006年 | 302篇 |
2005年 | 263篇 |
2004年 | 305篇 |
2003年 | 240篇 |
2002年 | 275篇 |
2001年 | 253篇 |
2000年 | 227篇 |
1999年 | 191篇 |
1998年 | 188篇 |
1997年 | 132篇 |
1996年 | 138篇 |
1995年 | 114篇 |
1994年 | 78篇 |
1993年 | 62篇 |
1992年 | 57篇 |
1991年 | 52篇 |
1990年 | 44篇 |
1989年 | 37篇 |
1988年 | 35篇 |
1987年 | 21篇 |
1986年 | 30篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 6篇 |
1982年 | 21篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1976年 | 4篇 |
1971年 | 4篇 |
1967年 | 2篇 |
1957年 | 4篇 |
排序方式: 共有6968条查询结果,搜索用时 10 毫秒
61.
通过非球面的零位补偿法,完成了对矩形大口径离轴非球面镜的检测。先用光学设计软件Zemax从理论上分析了在检测中会出现的现象,并结合计算机辅助装调技术,确定在检测过程中相对敏感的自由度,然后控制这些量,使补偿器和非球面的相对关系与理论设计相吻合,在Zygo相位干涉仪上测得最终结果。在λ=632.8nm时,中心圆口径与两个边缘圆口径面形误差RMS分别为0.022λ,0.037λ,0.032λ。检测结果,达到预期目的。 相似文献
62.
For each infinite cardinal κ, we give examples of 2κ many non‐isomorphic vertex‐transitive graphs of order κ that are pairwise isomorphic to induced subgraphs of each other. We consider examples of graphs with these properties that are also universal, in the sense that they embed all graphs with smaller orders as induced subgraphs. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 99–106, 2003 相似文献
63.
Robyn Pierce Kaye Stacey 《International Journal of Computers for Mathematical Learning》2004,9(1):59-93
This article suggests a framework to organise a cluster of variables that are associated with students' effective use of computer algebra systems (CAS) in mathematics learning. Based on a review of the literature and from the authors' own teaching experience, the framework identifies the main characteristics of students' interactions with CAS technology and how these may be used to monitor students' developing use of CAS; from this, the framework may be used to plan teaching in order to gain greater benefit from the availability of CAS. Four case studies describing students' development over a semester are reported. These demonstrate a variety of combinations of technical competencies and personal attributes. They indicate the importance of both the technical and personal aspects but suggest that negative attitudes rather than technical difficulties can limit the effective use of CAS. Finally practical suggestions are given for teaching strategies which may promote effective use of CAS.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
64.
Periodica Mathematica Hungarica - 相似文献
65.
66.
Charging of the surface of an oxide caused by the adsorption of hydrogen ions and ions of inert 1:1 electrolyte was investigated by using grand canonical Monte Carlo simulation technique. In particular, adsorption isotherms of protons as well as of ions of the electrolyte together with the resulting charge density of the surface were obtained for different system parameters. Also, the effect of the surface energetic heterogeneity and the concentration of the background electrolyte on the isotherms and the charge density curves was examined. Furthermore, lateral interactions in the mixed adsorbed phase were taken into account in the modeling of the system behavior. The obtained results, in general, suggest that the three factors mentioned above may have substantial influence on the charging mechanism at the liquid/oxide interface. 相似文献
67.
A method of simulated annealing in optimization of a computer generated holo-gram(CGH)is presented.The characteristics of energy in annealing curve are analyzed.Thecooling schedule such as giving an initial temperature,the temperature function,the numberof interactions and stopping criterion are discussed.As an example,an optimization of phaserelief kinoform,a CGH with multiple phase levels,is implemented. 相似文献
68.
杨力平 《应用数学学报(英文版)》1994,10(3):233-251
FREEBOUNDARYPROBLEMARISINGFROMEVAPORATIONFROMPOROUSMEDIUMYANGLIPING(杨力平)(DepartmentofAppliedMathematics,TsinghuaUniversity,Be... 相似文献
69.
In this paper, a model of translation gateway is proposed. The communications between IPv4 network and IPv6 network are realized by using the Microsoft intermediate driver technology in environment of Windows 2000. 相似文献
70.
We couple a morphological study of an immiscible binary AB mixture with a micromechanical simulation to determine how the spatial distribution of the A and B domains and the interfacial region (interphase) affects the mechanical behavior of the blend. The morphological studies are conducted through a three-dimensional Cahn-Hilliard (CH) simulation. Through the CH calculations, we obtain the size and structure of the domains for different blend compositions. The output of the CH model serves as the input to the Lattice Spring Model (LSM), which consists of a three-dimensional network of springs. In particular, the location of the different phases is mapped onto the LSM lattice and the appropriate force constants are assigned to the LSM sites. A stress is applied to the LSM lattice and we calculate the elastic response of the material. We find that the local stress and strain fields are highly dependent on the morphology of the system. By integrating the morphological and mechanical models, we can isolate how modifications in the composition of the mixture affect the macroscopic behavior. Thus, we can establish how choices made in the components affect the ultimate performance of the material. 相似文献