全文获取类型
收费全文 | 11403篇 |
免费 | 149篇 |
国内免费 | 1022篇 |
专业分类
化学 | 2797篇 |
晶体学 | 2篇 |
力学 | 389篇 |
综合类 | 203篇 |
数学 | 1054篇 |
物理学 | 2095篇 |
综合类 | 6034篇 |
出版年
2023年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2017年 | 58篇 |
2016年 | 69篇 |
2015年 | 100篇 |
2014年 | 28篇 |
2013年 | 69篇 |
2012年 | 84篇 |
2011年 | 1445篇 |
2010年 | 601篇 |
2009年 | 853篇 |
2008年 | 219篇 |
2007年 | 241篇 |
2006年 | 202篇 |
2005年 | 498篇 |
2004年 | 2042篇 |
2003年 | 1205篇 |
2002年 | 775篇 |
2001年 | 580篇 |
2000年 | 311篇 |
1999年 | 443篇 |
1998年 | 433篇 |
1997年 | 408篇 |
1996年 | 136篇 |
1995年 | 147篇 |
1994年 | 122篇 |
1993年 | 374篇 |
1992年 | 260篇 |
1991年 | 228篇 |
1990年 | 192篇 |
1989年 | 167篇 |
1988年 | 133篇 |
1987年 | 26篇 |
1986年 | 78篇 |
1985年 | 11篇 |
1984年 | 26篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
HAN Tao LU XiaoChun WANG Xue RAO YongNan ZOU DeCai YANG JianFei & WU YangYang National Time Service Center Xi'an China Key Laboratory of Precision Navigation Timing Technology Chinese Academy of Sciences Graduate University of the Chinese Academy of Sciences Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(6)
With the development of Global Navigation Satellite System (GNSS),the idea of GNSS interoperability is born and has become the focus of study in the field of satellite navigation.The popularity for GNSS to augment the interoperability with the existing ones necessitates the study of the assessment algorithm of this idea.In this paper,an assessment algorithm for interoperability comprehensive benefits based on the differential equation dynamical system is discussed.There are two important aspects in GNSS tha... 相似文献
62.
LI Ming DAI ChangJian & XIE Jun Key Laboratory of Display Materials Photoelectric Devices Ministry of Education Tianjin China School of Science Tianjin University of Technology Tianjin 《中国科学:物理学 力学 天文学(英文版)》2011,(6)
The odd-parity high-lying states of the Sm atom are investigated systematically by a three-color resonant excitation scheme with two different excitation paths.The two intermediate states,4f 6 6s7s 7 F 0 and 4f 6 6s7s 7 F 1 are employed for paths I and II,respectively.Fifty-seven bound states are detected with paths I and II in the energy range between 44188 and 45515 cm 1,while 64 autoionizing states are found in the energy range from 45528 to 45761 cm 1.Not only the level energies of all observed states,b... 相似文献
63.
ZENG ChunHua WANG Hua & HU JianHang Faculty of Science Kunming University of Science Technology Kunming China Province Engineering Research Center of Industrial Energy Conservation New Technology 《中国科学:物理学 力学 天文学(英文版)》2011,(8)
In this paper, we investigate the escape of Brownian particles and stochastic resonance (SR) with low-temperatures quantum fluctuations by using the quantum Smoluchowski equations at low-temperature. Two specific examples have been considered: one is the example of bistable system, and the other is the example of metastable system. The explicit expressions of the mean-first passage time (MFPT) and signal-to-noise ratio (SNR) for both specific examples are obtained, respectively. Based on the numerical compu... 相似文献
64.
LI GuangShun ZHOU XiaoHong ZHANG ShuangQuan ZHANG YuHu & MENG Jie Institute of Modern Physics Chinese Academy of Sciences Lanzhou China Graduate University of Chinese Academy of Sciences Beijing School of Physics SK Laboratory of Nuclear Physics & Technology Peking University Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(Z1)
Theoretical calculations have been performed for the ν9/2+[624](i13/2) and ν7/2-[503](f7/2) bands of 185Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is pro posed to be dominated by the ν9/2+[624](i13/2) component, while the negative-parity band shows strong mixing of ν7/2-[5... 相似文献
65.
JIA HongSheng JIA XiaoPeng XU Yue WAN LianRu JIE KaiKai & MA HongAn State Key Laboratory of Superhard Materials Jilin University Changchun China Test Science Experiment Center Changchun 《中国科学:物理学 力学 天文学(英文版)》2011,(1)
Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3-20 μm by the Ni 70 Mn 25 Co 5 alloy infiltration technique at high temperature and high pressure (HPHT).The surface residual stress of polycrystalline diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD).Measurements of the stress levels of PCDs show that the residual compressive stresses range from 0.12 to 0.22 GPa,which increase with th... 相似文献
66.
本文推导得到了一个新的等参数奇异单元,它仍然是四边形四分之一节点奇异元。数值实验表明,它要比常用的四边形四分之一节点奇异元精度更好,使用这种单元可以使断裂问题的有限元计算效果更好。在计算过程中还利用到改进等参变换。 相似文献
67.
蔡泽伟 《宁波大学学报(理工版)》1989,(2)
本文以伪随机二进制信号(PRBS)操舵,用同时测量轨迹与航向角的方法,计算得到漂角β,从而辨识了白箱模型(2.1),获得了操纵运动的水动力导数。并与PMM试验结果进行了比较,证实了本文方法的有效性。 相似文献
68.
69.
Path protections have become increasingly important for current mesh optical networks because fast restorations in generalized multiprotocol label switching(GMPLS) networks are uncertain.However,setting up additional disjoint paths to protect connections leads to more path setup blocking and signaling collisions.We analyze signaling collisions,path blocking and blocking probability,as well as calculate node-to-node blocking probabilities.A signaling-based path-segment protection(PSP) is proposed,which integrates segment protections and path protections as well as enhances the performance of path protections and ring protections.The setup of PSP connections causes less blocking probability than the setup of path protection connections in the simulations. 相似文献
70.
用溶胶-凝胶(so-lgel)法制备了多铁Bi1-xLaxMnO3(BLMO,0.1≤x≤0.4)系列样品.样品的结构表征(X-射线衍射,扫描电子显微镜)及差热-热重(TG-DTA)分析测量显示,形成稳定的BLMO钙钛矿相的烧结温度位于900~950℃.La掺杂对BLMO样品(950℃烧结)的结构和磁性能的影响也被仔细研究.结果显示,随着La掺杂减少,样品中BLMO钙钛矿相减弱,铁磁转变温度(TC)由53K降至41K,而饱和磁化强度经历了先降低再升高的变化.这可归因于La含量较少的样品中Bi空位浓度的增加诱导了Mn-O-Mn键角的减小和局域Mn4+离子的增多,使得Mn3+和Mn4+离子的铁磁超交换增强和Mn3+离子的dz2轨道有序受到局域破坏. 相似文献