全文获取类型
收费全文 | 67804篇 |
免费 | 12422篇 |
国内免费 | 15163篇 |
专业分类
化学 | 26667篇 |
晶体学 | 1688篇 |
力学 | 3102篇 |
综合类 | 1551篇 |
数学 | 6457篇 |
物理学 | 19552篇 |
无线电 | 36372篇 |
出版年
2024年 | 381篇 |
2023年 | 1075篇 |
2022年 | 2645篇 |
2021年 | 2570篇 |
2020年 | 2202篇 |
2019年 | 2082篇 |
2018年 | 2110篇 |
2017年 | 2945篇 |
2016年 | 2258篇 |
2015年 | 3434篇 |
2014年 | 4149篇 |
2013年 | 5142篇 |
2012年 | 5444篇 |
2011年 | 5802篇 |
2010年 | 5722篇 |
2009年 | 5932篇 |
2008年 | 6324篇 |
2007年 | 5904篇 |
2006年 | 5688篇 |
2005年 | 4665篇 |
2004年 | 3665篇 |
2003年 | 2464篇 |
2002年 | 2455篇 |
2001年 | 2395篇 |
2000年 | 2470篇 |
1999年 | 1196篇 |
1998年 | 557篇 |
1997年 | 412篇 |
1996年 | 405篇 |
1995年 | 317篇 |
1994年 | 317篇 |
1993年 | 338篇 |
1992年 | 262篇 |
1991年 | 223篇 |
1990年 | 193篇 |
1989年 | 184篇 |
1988年 | 183篇 |
1987年 | 163篇 |
1986年 | 118篇 |
1985年 | 81篇 |
1984年 | 99篇 |
1983年 | 86篇 |
1982年 | 55篇 |
1981年 | 49篇 |
1980年 | 47篇 |
1979年 | 45篇 |
1978年 | 18篇 |
1971年 | 11篇 |
1965年 | 24篇 |
1959年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Ming Zhao WANG Guan Liang CAI Ling XIA Jun Jian YAO Hong Yan CHEN Zhao Xing MENG Bo Li LIUDepartment of Chemistry Beijing Normal University Beijing Chemical Defense Institute PLA Beijing 《中国化学快报》2004,15(4):495-497
The crystal structures of two potential tumor imaging agents and therapeutic agents -copper(Ⅱ) complexes with salicylidene-tyrosinato Schiff base and nitrogen-donor chelating Lewis base, [Cu(sal-tyr)(bipy)] 1 and [Cu(sal-tyr)(phen)]2CH3OH 2 are presented. Our work is helpful to get deep understanding of novel 64Cu tumor imaging agents and therapeutic agents. 相似文献
72.
73.
LI Zi-jian LIU Ning LIU Zhi-qiang LIU Shu-ying HAN Qi-de ZHANG You-yi . Institute of Vascular Medicine Peking University Third Hospital Key Laboratory of Molecular Cardiovascular Sciences Ministry of Education Beijing P. R. China . Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun P. R. China 《高等学校化学研究》2006,22(3):319-323
Introduction Adrenoceptors(ARs),membersofthesuperfami lyofG proteincoupledreceptors,arethemostimpor tantreceptorsinvolvedincardiacregulation[1].ARsin cardiacmuscleincludebothαARsandβARssub types,whileinmostmammalianheart,βARsarethe predominantsubtypes.… 相似文献
74.
Cobalt antidot arrays with different thicknesses are fabricated by rf magnetron sputtering onto porous alumina substrates. Scanning electron microscopy and grazing incidence x-ray diffraction are employed to characterize the morphology and crystal structure of the antidot array, respectively. The temperature dependence of magnetic properties shows that in the temperature range 5K--300K, coercivity and squareness increase firstly, reach their maximum values, then decrease. The anomalous temperature dependences of coercivity and squareness are discussed by considering the pinning effect of the antidot and the magnetocrystalline anisotropy. 相似文献
75.
主要介绍了丝绸之路上多元文化的典型代表——艾德莱斯绸.文章重点介绍了艾德莱斯绸的历史和传说,扎经染色工艺,各类艾德莱斯绸的特点及典型的艾德莱斯绸图案. 相似文献
76.
本文给出了Banach空间广义分解定理的一个初等证明,并利用它来证明两个对称不等式.这是首次在Banach空间获得这样的不等式. 相似文献
77.
The complete and incomplete aggregation-annihilation processes are investigated with the method of generating function, and the scale exponents are obtained exactly. We find that the scale exponents of incomplete aggregation-annihilation process are different from the previous exponents obtained by different methods. The time dependence of the total number of clusters and the total mass of clusters are analytically obtained. 相似文献
78.
79.
LIU Shu-ping JIA Yue-hu 《半导体光子学与技术》2006,12(1):21-24
According to Maxwell's theory, the optical transmission characteristics in GeSi/Si superlattice nanocrystalline layer have been analyzed and calculated. The calculated result shows that when the total thickness L is 340 nm, the single mode lightwave can be transmitted only at periodic number M≥15.5. In addition, at the direction of transmission, when the transmission distance is larger than 500 μm, the lightwave intensity is decreased greatly. Based on the above parameters, the design and manufacture of GeSi/Si superlattice nanocrystalline photodetector are carried out. 相似文献
80.
Organic electroluminescent thin film using Znq2(Znq2) as the emitting layer material with structure of glass/ITO/Znq2/Al(cell) was fabricated.The V-I curve ,V-B curve and electroluminescent spectra of the cell were measured.Meanwhile the fluorescent spectra, excited spectra and absorption spectra of Znq2 with power and film states were also measured. 相似文献