全文获取类型
收费全文 | 1770篇 |
免费 | 88篇 |
国内免费 | 3篇 |
专业分类
化学 | 1397篇 |
晶体学 | 11篇 |
力学 | 12篇 |
数学 | 143篇 |
物理学 | 298篇 |
出版年
2023年 | 25篇 |
2022年 | 67篇 |
2021年 | 107篇 |
2020年 | 67篇 |
2019年 | 56篇 |
2018年 | 63篇 |
2017年 | 38篇 |
2016年 | 109篇 |
2015年 | 58篇 |
2014年 | 85篇 |
2013年 | 117篇 |
2012年 | 120篇 |
2011年 | 137篇 |
2010年 | 83篇 |
2009年 | 69篇 |
2008年 | 114篇 |
2007年 | 87篇 |
2006年 | 84篇 |
2005年 | 79篇 |
2004年 | 66篇 |
2003年 | 43篇 |
2002年 | 29篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 17篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1961年 | 1篇 |
1960年 | 2篇 |
排序方式: 共有1861条查询结果,搜索用时 171 毫秒
991.
Syrota Natalia А. Kemskiy Sergiy V. Bol’but Andriy V. Vovk Mikhailo V. 《Chemistry of Heterocyclic Compounds》2019,55(11):1092-1097
Chemistry of Heterocyclic Compounds - The corresponding ethyl 5-carbonylglycinates were synthesized by condensation of 4-(Boc-amino)-1,2,3-triazole-5-carboxylic acids with ethyl glycinate... 相似文献
992.
Elena M. Gmez-Sez Natalia Moratalla-Lpez Cndida Lorenzo Herminia Vergara Gonzalo L. Alonso 《Molecules (Basel, Switzerland)》2021,26(7)
At present, the development of new agri-food products, including flavored meat products presented in ready-to-eat vacuum packs, is encouraged. The addition of ingredients used as flavoring agents creates the need to be able to determine the volatile compounds responsible for their characteristic aroma. The aim of this study is to propose, develop, and validate a new method that uses headspace-stir bar sorptive extraction-gas chromatography/mass spectrometry (HS-SBSE-GC/MS) to determine the saffron aroma in cured ham flavored with this spice. Results showed that safranal was the main volatile compound that could be identified and quantified in cured ham flavored with saffron. This analytical method was adequate in terms of linearity, selectivity, sensitivity, and accuracy. To our knowledge, this is the first time that an HS-SBSE-GC/MS method for determining the saffron aroma of flavored cured ham has been developed and validated, and it is of interest to agri-food industries. 相似文献
993.
994.
Tatyana N. Lomova Maria E. Klyueva Elena Yu. Tyulyaeva Natalia G. Bichan Svetlana V. Zaitseva Sergey A. Zdanovich 《Mendeleev Communications》2012,22(5):281-283
The H-associate as a new protonated form of metalloporphyrins in strong acid media has been obtained and a qualitative reaction for its determination has been found; the properties and structure of a protonated form have been analyzed by spectral methods and quantum-chemical calculations. 相似文献
995.
996.
Maxim Bykov Stella Chariton Elena Bykova Saiana Khandarkhaeva Timofey Fedotenko Alena V. Ponomareva Johan Tidholm Ferenc Tasndi Igor A. Abrikosov Pavel Sedmak Vitali Prakapenka Michael Hanfland Hanns‐Peter Liermann Mohammad Mahmood Alexander F. Goncharov Natalia Dubrovinskaia Leonid Dubrovinsky 《Angewandte Chemie (International ed. in English)》2020,59(26):10666-10666
997.
Ammar N. Natsheh J. Gordon Kettleborough Natalia B. Janson 《Chaos, solitons, and fractals》2009,40(5):2500-2508
This paper presents a delayed feedback control scheme for eliminating chaotic behaviour in a peak current-mode controlled DC–DC boost converter operating in the continuous current conduction mode. Experimental results and FORTRAN simulations show the effectiveness and robustness of the scheme. 相似文献
998.
A new zwitterionic compound, aaptanone, having a rare oxygenated 1,6-naphthyridine core, has been isolated from the Vietnamese marine sponge Aaptos aaptos, along with the known metabolites, aaptamine, isoaaptamine, and their hydrochloride salts. The structure of aaptanone was determined as 8-methoxy-1-methyl-5,6-dioxo-5,6-dihydro-4H-benzo[de]-1,6-naphthyridine-1-ium-9-olate from spectroscopic data, X-ray analysis, and by spectroscopic analysis of an N-methyl derivative. 相似文献
999.
1000.
We characterize the finite dimensional asymmetric normed spaces which are right bounded and the relation of this property with the natural compactness properties of the unit ball, such as compactness and strong compactness. In contrast with some results found in the existing literature, we show that not all right bounded asymmetric norms have compact closed balls. We also prove that there are finite dimensional asymmetric normed spaces that satisfy that the closed unit ball is compact, but not strongly compact, closing in this way an open question on the topology of finite dimensional asymmetric normed spaces. In the positive direction, we will prove that a finite dimensional asymmetric normed space is strongly locally compact if and only if it is right bounded. 相似文献