全文获取类型
收费全文 | 18776篇 |
免费 | 3717篇 |
国内免费 | 5480篇 |
专业分类
化学 | 15025篇 |
晶体学 | 588篇 |
力学 | 1259篇 |
综合类 | 617篇 |
数学 | 2406篇 |
物理学 | 8078篇 |
出版年
2024年 | 27篇 |
2023年 | 201篇 |
2022年 | 508篇 |
2021年 | 523篇 |
2020年 | 616篇 |
2019年 | 652篇 |
2018年 | 559篇 |
2017年 | 679篇 |
2016年 | 827篇 |
2015年 | 940篇 |
2014年 | 1181篇 |
2013年 | 1445篇 |
2012年 | 1530篇 |
2011年 | 1752篇 |
2010年 | 1484篇 |
2009年 | 1605篇 |
2008年 | 1859篇 |
2007年 | 1582篇 |
2006年 | 1484篇 |
2005年 | 1257篇 |
2004年 | 1046篇 |
2003年 | 805篇 |
2002年 | 987篇 |
2001年 | 862篇 |
2000年 | 897篇 |
1999年 | 482篇 |
1998年 | 278篇 |
1997年 | 193篇 |
1996年 | 215篇 |
1995年 | 190篇 |
1994年 | 183篇 |
1993年 | 195篇 |
1992年 | 157篇 |
1991年 | 102篇 |
1990年 | 114篇 |
1989年 | 95篇 |
1988年 | 94篇 |
1987年 | 74篇 |
1986年 | 46篇 |
1985年 | 36篇 |
1984年 | 37篇 |
1983年 | 45篇 |
1982年 | 13篇 |
1981年 | 26篇 |
1980年 | 19篇 |
1979年 | 24篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1974年 | 8篇 |
1971年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 183 毫秒
111.
A Novel Analytical Approach for Multi-Layer Diaphragm-Based Optical Microelectromechanical-System Pressure Sensors
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An optical microelectromechanical-system (MEMS) pressure sensor based on multi-layer circular diaphragm is described and analysed by using the proposed novel analytical approach and the traditional transfer matrix method. The analytical expressions of the deflection of multi-layer diaphragm and absolute optical reflectance are derived respectively. The influence of residual stress on the deflection of diaphragm is also analysed. Simulation results given by the finite element method are consistent with the ones which are analysed by using the analytical approach. The analytical approach will be helpful to design and fabricate the optical MEMS pressure sensors with multi-layer diaphragm based on Fabry-Perot interferometry. 相似文献
112.
113.
Wei-nan E Ping-bing Ming 《应用数学学报(英文版)》2007,23(4):529-550
We study continuum and atomistic models for the elastodynamics of crystalline solids at zerotemperature.We establish sharp criterion for the regime of validity of the nonlinear elastic wave equationsderived from the well-known Cauchy-Born rule. 相似文献
114.
我国低温等离子体研究进展(Ⅰ) 总被引:7,自引:0,他引:7
低温等离子体物理与技术的研究在国内受到了越来越多的重视.在等离子体中发现的一些有趣的物理现象,如磁场重联、尘埃等离子体等,使人们对等离子体物理的研究掀起了新的热潮.在应用方面,几乎所有理工类实验室都有涉及低温等离子体技术的实验装置,这使得在我国低温等离子体应用方面的研究非常普及,包括微电子工业中的等离子体工艺,各种坚硬、耐腐蚀、耐摩擦材料的制备,纳米材料的制备,聚合物以及生物材料的表面改性,等等.随着低温等离子体技术的发展,低温等离子体的诊断技术也随之发展起来.文章简要地介绍了近几年来低温等离子体研究在我国的发展,介绍了一些有关低温等离子体的热点研究课题. 相似文献
115.
116.
Hong Ming ZHANG Xian Hong WANG Xiao Jiang ZHAO Ji LI Fo Song WANG 《中国化学快报》2006,17(4):437-440
A novel method for the preparation of oligothiophene molecular wires is described via a bi-directional solid-phase synthesis. Using an alternating sequence of bromination and Stille coupling reactions, oligomers were obtained up to the heptamer in excellent yield and purity. 相似文献
117.
HL-2Aƫ�����ṹ���켰�ȸ��ɷ��� 总被引:1,自引:1,他引:0
根据HL-2A装置改造的初步方案,选择优化的偏滤器位形所决定的参数,设计出可采取的偏滤器结构及水冷方式。外靶板和拱顶板上采用双剪切连接件和环向水路具有极向水流的冷却方式。通过ANSYS编码对靶板的热负荷进行分析,结果表明这样的冷却方式在降低流速要求的条件下可以提高靶板表面承载能力。 相似文献
118.
强混合样本下回归加权估计的一致渐近正态性 总被引:5,自引:0,他引:5
在强混合样本下,讨论固定设计回归模型的加权函数估计的一致渐近正态性,给出一致渐近正态性的收敛速度,这个速度接近n-1/6. 相似文献
119.
A series of complexes formed between halogen-containing molecules and ammonia have been investigated by means of the atoms in molecules (AIM) approach to gain a deeper insight into halogen bonding. The existence of the halogen bond critical points (XBCP) and the values of the electron density (Pb) and Laplacian of electron density (V2pb) at the XBCP reveal the closed-shell interactions in these complexes. Integrated atomic properties such as charge, energy, polarization moment, volume of the halogen bond donor atoms, and the corresponding changes (△) upon complexation have been calculated. The present calculations have demonstrated that the halogen bond represents different AIM properties as compared to the well-documented hydrogen bond. Both the electron density and the Laplacian of electron density at the XBCP have been shown to correlate well with the interaction energy, which indicates that the topological parameters at the XBCP can be treated as a good measure of the halogen bond strength In addition, an excellent linear relationship between the interatomic distance d(X…N) and the logarithm of Pb has been established. 相似文献
120.
We report viscometric data collected in a Couette rheometry on dilute, single‐solvent polystyrene (PS)/dioctyl phthalate (DOP) solutions over a variety of polymer molecular weights (5.5 × 105 ≤ Mw ≤ 3.0 × 106 Da) and system temperatures (288 K ≤ T ≤ 318 K). In view of the essential viscometric features, the current data may be classified into three categories: The first concerns all the investigated solutions at low shear rates, where the solution properties are found to agree excellently with the Zimm model predictions. The second includes all sample solutions, except for high‐molecular‐weight PS samples (Mw ≥ 2.0 × 106 Da), where excellent time–temperature superposition is observed for the steady‐state polymer viscosity at constant polymer molecular weights. No similar superposition applies at a constant temperature but varied polymer molecular weights, however. The third appears to be characteristic of dilute high‐molecular‐weight polymer solutions, for which the effects of temperature on the viscosity curve are further complicated at high shear rates. The implications concerning the relative importance of hydrodynamic interactions, segmental interactions, and chain extensibility with increasing polymer molecular weight, system temperature, and shear rate are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 787–794, 2006 相似文献