全文获取类型
收费全文 | 206341篇 |
免费 | 1756篇 |
国内免费 | 887篇 |
专业分类
化学 | 95110篇 |
晶体学 | 2840篇 |
力学 | 11664篇 |
综合类 | 5篇 |
数学 | 44192篇 |
物理学 | 55173篇 |
出版年
2018年 | 10969篇 |
2017年 | 10732篇 |
2016年 | 7341篇 |
2015年 | 1862篇 |
2014年 | 1670篇 |
2013年 | 5264篇 |
2012年 | 7259篇 |
2011年 | 14911篇 |
2010年 | 8391篇 |
2009年 | 8545篇 |
2008年 | 10596篇 |
2007年 | 12788篇 |
2006年 | 4486篇 |
2005年 | 5468篇 |
2004年 | 5170篇 |
2003年 | 5278篇 |
2002年 | 4218篇 |
2001年 | 3930篇 |
2000年 | 3071篇 |
1999年 | 2405篇 |
1998年 | 2124篇 |
1997年 | 2057篇 |
1996年 | 2080篇 |
1995年 | 1953篇 |
1994年 | 1713篇 |
1993年 | 1738篇 |
1992年 | 1903篇 |
1991年 | 1867篇 |
1990年 | 1784篇 |
1989年 | 1807篇 |
1988年 | 1804篇 |
1987年 | 1779篇 |
1986年 | 1699篇 |
1985年 | 2253篇 |
1984年 | 2354篇 |
1983年 | 1960篇 |
1982年 | 2302篇 |
1981年 | 2120篇 |
1980年 | 2164篇 |
1979年 | 2158篇 |
1978年 | 2276篇 |
1977年 | 2176篇 |
1976年 | 2172篇 |
1975年 | 2106篇 |
1974年 | 1956篇 |
1973年 | 2180篇 |
1972年 | 1331篇 |
1971年 | 1009篇 |
1968年 | 1080篇 |
1967年 | 1125篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Arthur W. Apter 《Mathematical Logic Quarterly》2006,52(5):457-463
We construct models for the level by level equivalence between strong compactness and supercompactness in which for κ the least supercompact cardinal and δ ≤ κ 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
63.
64.
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
65.
66.
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
67.
C. A. Beattie M. B. Boisen Jr. L. W. Johnson 《Journal of Optimization Theory and Applications》1991,68(1):203-203
Corrections to the last two equations of Ref. 1 are given. 相似文献
68.
P. Cifra F. E. Karasz W. J. Macknight 《Journal of Polymer Science.Polymer Physics》1991,29(11):1389-1395
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
69.
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
70.
Summary The paper discusses some developments in the coordinate partitioning method for the dynamic analysis of constrained/closed-loop multibody systems. First, the method is reformulated to a more compact form. Then, a simple and reliable projective criterion for choosing the best coordinates from the redundant ones is proposed, and some advantages are pointed out that may arise in the method by applying inverse kinematics algorithms. Finally, the problem of determination ofphysical reactions of constraints and closing conditions is discussed. A four-bar linkage mechanism serves for an illustration of some aspects of the paper.
On leave from the Department of Mechanics, Technical University of Radom, ul. Malczewskiego 29, 26-600 Radom, Poland 相似文献
Ein Projektionskriterium zur Koordinatenwahl bei Mehrkörpersystemen mit kinematischen Schleifen
Übersicht Bei der Simulation der Bewegunsgleichungen von Mehrkörpersystemen mit kinematischen Schleifen in Minimalform stellt sich die Frage nach der Wahl günstiger verallgemeinerter Koordinaten. Hierfür wird ein Projektionskriterium vorgeschlagen, welches die Trennung der systembeschreibenden redundanten Koordinaten in die verallgemeinerten und davon abhängige Koordinaten gestattet. Durch Anwendung eines Verfahrens zur Rückwärtstransformation der kinematischen Beschreibung lassen sich in diesen explizite Schließbedingungen formulieren, was sich bei der Simulation vorteilhaft auswirkt; diese kann ohne Verletzung der Schließbedingungen erfolgen. Es wird auch gezeigt, wie auch bei Verwendung verallgemeinerter Koordinatenphysikalisch interpretierbare Reaktionen ermittelt werden können. Als Anwendungsbeispiel dient ein ebenes Viergelenk.
On leave from the Department of Mechanics, Technical University of Radom, ul. Malczewskiego 29, 26-600 Radom, Poland 相似文献