首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   135507篇
  免费   1574篇
  国内免费   545篇
化学   75861篇
晶体学   2137篇
力学   5164篇
综合类   5篇
数学   13554篇
物理学   40905篇
  2016年   1467篇
  2015年   1176篇
  2014年   1573篇
  2013年   5242篇
  2012年   3963篇
  2011年   5164篇
  2010年   3117篇
  2009年   2839篇
  2008年   4619篇
  2007年   4673篇
  2006年   4765篇
  2005年   4708篇
  2004年   4099篇
  2003年   3666篇
  2002年   3551篇
  2001年   3711篇
  2000年   2806篇
  1999年   2306篇
  1998年   2021篇
  1997年   2019篇
  1996年   1974篇
  1995年   1874篇
  1994年   1651篇
  1993年   1637篇
  1992年   1834篇
  1991年   1821篇
  1990年   1731篇
  1989年   1741篇
  1988年   1740篇
  1987年   1733篇
  1986年   1633篇
  1985年   2221篇
  1984年   2344篇
  1983年   1948篇
  1982年   2271篇
  1981年   2106篇
  1980年   2146篇
  1979年   2115篇
  1978年   2233篇
  1977年   2128篇
  1976年   2147篇
  1975年   2092篇
  1974年   1923篇
  1973年   2130篇
  1972年   1299篇
  1971年   984篇
  1970年   919篇
  1969年   927篇
  1968年   1054篇
  1967年   1104篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
We construct models for the level by level equivalence between strong compactness and supercompactness in which for κ the least supercompact cardinal and δκ any cardinal which is either a strong cardinal or a measurable limit of strong cardinals, 2δ > δ + and δ is < 2δ supercompact. In these models, the structure of the class of supercompact cardinals can be arbitrary, and the size of the power set of κ can essentially be made as large as desired. This extends and generalizes [5, Theorem 2] and [4, Theorem 4]. We also sketch how our techniques can be used to establish a weak indestructibility result. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
52.
53.
54.
This paper presents the development and laboratory evaluation of a PM10/2.5/1.0 trichotomous sampling inlet that consists of two main parts: a previously designed PM10 size‐selective inlet part and a PM2.5/1.0 two‐stage virtual impactor, which was newly fabricated and attached serially to the PM10 size selective inlet part. Particles are collected in three locations through the trichotomous sampling inlet to provide for not only particle concentration measurements of PM10, PM2.5 and PM1.0, but also those of PM2.5–10 and PM1.0–2.5.  相似文献   
55.
56.
57.
A system for display of magnetic resonance (MR) spectroscopic imaging (SI) data is described which provides for efficient review and analysis of the multidimensional spectroscopic and spatial data format of this technique. Features include the rapid display of spectra from selected image voxels, formation of spectroscopic images, spectral and image data processing operations, methods for correlating spectroscopic image data with high resolution 1H MR images, and hardcopy facilities. Examples are shown for 31P and 1H spectroscopic imaging studies obtained in human and rat brain.  相似文献   
58.
Corrections to the last two equations of Ref. 1 are given.  相似文献   
59.
Local ordering in miscible binary polymer blends with strong attractive interactions between the two types of chains was investigated by computer simulation of allowable conformations on an incompressible cubic lattice. A tendency toward maximum ordering (in which chains pack in alternate parallel rows) is shown by the calculation of pair correlations and in “snapshots” of the mixtures. A specific directional interaction is not necessarily required for ordering. A comparison of these results with those recently obtained using mean-field theory is presented. The heat capacity of mixing was also calculated and found to be positive, with a value close to that reported experimentally.  相似文献   
60.
We engage a study of nonmodal linear logic which takes times ⊗ and the linear conditional ⊸ to be the basic connectives instead of times and linear negation () as in Girard's approach. This difference enables us to obtain a very large subsystem of linear logic (called positive linear logic) without an involutionary negation (if the law of double negation is removed from linear logic in Girard's formulation, the resulting subsystem is extremely limited). Our approach enables us to obtain several natural models for various subsystems of linear logic, including a generic model for the so-called minimal linear logic. In particular, it is seen that these models arise spontaneously in the transition from set theory to multiset theory. We also construct a model of full (nonmodal) linear logic that is generic relative to any model of positive linear logic. However, the problem of constructing a generic model for positive linear logic remains open. Bibliography: 2 titles. Published inZapiski Nauchnykh Seminarov POMI, Vol. 220, 1995, pp. 23–35. Original  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号