全文获取类型
收费全文 | 482575篇 |
免费 | 2531篇 |
国内免费 | 618篇 |
专业分类
化学 | 198929篇 |
晶体学 | 6453篇 |
力学 | 27461篇 |
综合类 | 9篇 |
数学 | 73867篇 |
物理学 | 144685篇 |
无线电 | 34320篇 |
出版年
2021年 | 4168篇 |
2020年 | 4631篇 |
2019年 | 5629篇 |
2018年 | 13404篇 |
2017年 | 13765篇 |
2016年 | 12897篇 |
2015年 | 5013篇 |
2014年 | 9118篇 |
2013年 | 16827篇 |
2012年 | 16399篇 |
2011年 | 24073篇 |
2010年 | 17989篇 |
2009年 | 18621篇 |
2008年 | 22545篇 |
2007年 | 25011篇 |
2006年 | 14348篇 |
2005年 | 15788篇 |
2004年 | 13783篇 |
2003年 | 13526篇 |
2002年 | 12488篇 |
2001年 | 11637篇 |
2000年 | 9480篇 |
1999年 | 7213篇 |
1998年 | 6637篇 |
1997年 | 6395篇 |
1996年 | 5803篇 |
1995年 | 5173篇 |
1994年 | 5238篇 |
1993年 | 5159篇 |
1992年 | 5139篇 |
1991年 | 5604篇 |
1990年 | 5623篇 |
1989年 | 5626篇 |
1988年 | 5236篇 |
1987年 | 5153篇 |
1986年 | 4814篇 |
1985年 | 5704篇 |
1984年 | 5900篇 |
1983年 | 5011篇 |
1982年 | 5208篇 |
1981年 | 4872篇 |
1980年 | 4510篇 |
1979年 | 5145篇 |
1978年 | 5336篇 |
1977年 | 5424篇 |
1976年 | 5614篇 |
1975年 | 5208篇 |
1974年 | 5015篇 |
1973年 | 5306篇 |
1972年 | 4405篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
71.
Kaplunov I. A. Kolesnikov A. I. Kropotov G. I. Rogalin V. E. 《Optics and Spectroscopy》2019,126(3):191-194
Optics and Spectroscopy - The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the... 相似文献
72.
Dr. Liat Avram Dr. Václav Havel Ronit Shusterman-Krush Dr. Mark A. Iron Dr. Moritz Zaiss Prof. Vladimír Šindelář Dr. Amnon Bar-Shir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1687-1690
The accumulated knowledge regarding molecular architectures is based on established, reliable, and accessible analytical tools that provide robust structural and functional information on assemblies. However, both the dynamicity and low population of noncovalently interacting moieties within studied molecular systems limit the efficiency and accuracy of traditional methods. Herein, the use of a saturation transfer-based NMR approach to study the dynamic binding characteristics of an anion to a series of synthetic receptors derived from bambusuril macrocycles is demonstrated. The exchange rates of BF4− are mediated by the side chains on the receptor (100 s−1<kex<5000 s−1), which play a critical role in receptor-anion binding dynamics. The signal amplification obtained with this approach allows for the identification of different types of intermolecular interactions between the receptor and the anion, something that could not have been detected by techniques hitherto used to study molecular assemblies. These findings, which are supported by a computational molecular dynamic study, demonstrate the uniqueness and added value of this NMR method. 相似文献
73.
74.
75.
J. Conrad J. Cohen-Tanugi L. E. Strigari 《Journal of Experimental and Theoretical Physics》2015,121(6):1104-1135
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments. 相似文献
76.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
77.
Kondakov N. N. Mel´nikova T. M. Chekryzhova T. V. Mel´nikova M. V. Zinin A. I. Torgov V. I. Chizhov A. O. Kononov L. O. 《Russian Chemical Bulletin》2015,64(5):1142-1148
Russian Chemical Bulletin - Terminal disaccharide fragment of phenolic glycolipid from Mycobacterium leprae (PGL-I) was synthesized as a glycoside with 4-(2-aminoethoxy)phenyl aglycon. The obtained... 相似文献
78.
79.
80.