全文获取类型
收费全文 | 834篇 |
免费 | 42篇 |
国内免费 | 4篇 |
专业分类
化学 | 707篇 |
晶体学 | 5篇 |
力学 | 7篇 |
数学 | 108篇 |
物理学 | 53篇 |
出版年
2023年 | 10篇 |
2022年 | 17篇 |
2021年 | 21篇 |
2020年 | 19篇 |
2019年 | 24篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 23篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 56篇 |
2012年 | 55篇 |
2011年 | 75篇 |
2010年 | 38篇 |
2009年 | 29篇 |
2008年 | 47篇 |
2007年 | 54篇 |
2006年 | 51篇 |
2005年 | 39篇 |
2004年 | 46篇 |
2003年 | 29篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1944年 | 2篇 |
1940年 | 2篇 |
1937年 | 2篇 |
1926年 | 3篇 |
排序方式: 共有880条查询结果,搜索用时 31 毫秒
111.
For optimization problems with multifunction objective and constraints, duality theorems are proved for analogs of the Wolfe and Mond–Weir dual problems, assuming that the multifunctions satisfy a generalization of the invex property for functions. Several characterizations of generalized invexity are obtained. 相似文献
112.
113.
Dagmar Medková Emma Skopin Werner Varnhorn 《Mathematical Methods in the Applied Sciences》2013,36(16):2237-2242
We study the Robin problem for the scalar Oseen equation in an open n‐dimensional set with compact Ljapunov boundary. We prescribe two types of Robin boundary conditions, and prove the unique solvability of these problems as well as a representation formula for the solution in form of a scalar Oseen single layer potential. Moreover, we prove the maximum principle for the solution to the Robin problem of the scalar Oseen equation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
114.
Alexander J. Boddy Dominic P. Affron Christopher J. Cordier Emma L. Rivers Alan C. Spivey James A. Bull 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1472-1476
Methods that provide rapid access to new heterocyclic structures in biologically relevant chemical space provide important opportunities in drug discovery. Here, a strategy is described for the preparation of 2,2‐disubstituted azetidines, pyrrolidines, piperidines, and azepanes bearing ester and diverse aryl substituents. A one‐pot rhodium catalyzed N–H insertion and cyclization sequence uses diazo compounds to stitch together linear 1,m‐haloamines (m=2–5) to rapidly assemble 4 ‐, 5 ‐, 6 ‐, and 7 ‐membered saturated nitrogen heterocycles in excellent yields. Over fifty examples are demonstrated, including examples with diazo compounds derived from biologically active compounds. The products can be functionalized to afford α,α‐disubstituted amino acids and applied to fragment synthesis. 相似文献
115.
Notbohm J. Napiwocki B. N. de Lange W. J. Stempien A. Saraswathibhatla A. Craven R. J. Salick M. R. Ralphe J. C. Crone W. C. 《Experimental Mechanics》2020,60(4):571-571
Experimental Mechanics - The authors would like to correct the sentence “The mass ratio……” in the subsection on Engineered Substrate System in MATERIALS AND METHODS, to read: 相似文献
116.
Use of atmospheric pressure solids analysis probe time‐of‐flight mass spectrometry to screen for plasticisers in gaskets used in contact with foods
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
117.
Jenny Halleröd Chrisitan Ekberg Ivan Kajan Emma Aneheim 《Journal of solution chemistry》2018,47(6):1021-1036
The two organic ligands 6,6′-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[1,2,4]triazin-3-yl)[2,2′]bipyridine (CyMe\(_{4}\)-BTBP) and tri-butyl phosphate (TBP) have previously been investigated in different diluents for use within recycling of used nuclear fuel through solvent extraction. The thermodynamic parameters, \(K_{\mathrm{S}}\), \(\Delta C_{p}\), \(\Delta H^{0}\) and \(\Delta S^{0}\), of the CyMe\(_{4}\)-BTBP solubility in three diluents (cyclohexanone, octanol and phenyl trifluoromethyl sulfone) mixed with TBP have been studied at 288, 298 and 308 K, both as pristine solutions and pre-equilibrated with 4 mol\(\cdot \)L\(^{-1}\) nitric acid. In addition, the amount of acid in the organic phase and density change after pre-equilibration have been measured. The solubility of CyMe\(_{4}\)-BTBP increases with an increased temperature in all systems, especially after acid pre-equilibration. This increased CyMe\(_{4}\)-BTBP solubility after pre-equilibration could be explained by acid dissolution into the solvent. Comparing the \(\Delta H^{0}\) and \(\Delta S^{0}\) calculated using \(\Delta C_{p}\) with the same parameters derived from a linear fit indicates temperature independence of all three thermodynamic systems. The change in enthalpy is positive in all solutions. 相似文献
118.
Jixin Qiao Petra Lagerkvist Ilia Rodushkin Susanna Salminen-Paatero Per Roos Syverin Lierhagen Karl Andreas Jensen Emma Engstrom Yann Lahaye Lindis Skipperud 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):565-580
Inductively coupled plasma mass spectrometry (ICP-MS) techniques are widely used for determination of long-lived radionuclides and their isotopic ratios in the nuclear fields. Uranium (U) and Plutonium (Pu) isotopes have been determined by many researchers with ICP-MS due to its relatively high sensitivity and short measurement time. In this work, an inter-laboratory comparison exercise among the Nordic countries was performed, focusing on the measurement of U and Pu isotopes in certified reference materials by ICP-MS. The performance and characters of different ICP-MS instruments are evaluated and discussed in this paper. 相似文献
119.
Rondahl Stina Holmgren Pointurier Fabien Ahlinder Linnea Ramebäck Henrik Marie Olivier Ravat Brice Delaunay François Young Emma Blagojevic Ned Hester James R. Thorogood Gordon Nelwamondo Aubrey N. Ntsoane Tshepo P. Roberts Sarah K. Holliday Kiel S. 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):395-408
Journal of Radioanalytical and Nuclear Chemistry - This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear... 相似文献
120.
Total Synthesis of Tambromycin by Combining Chemocatalytic and Biocatalytic C−H Functionalization
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Xiao Zhang Emma King‐Smith Prof. Dr. Hans Renata 《Angewandte Chemie (International ed. in English)》2018,57(18):5037-5041
A combination of genomic and metabolomic approaches recently resulted in the identification of a nonribosomal tetrapeptide tambromycin, which possesses promising antiproliferative activity and several unusual structural features, including a densely substituted indole, a methyloxazoline ring, and an unusual pyrrolidine‐containing amino acid called tambroline. In this work, we identify a concise synthetic route to access tambromycin, which relies on the strategic use of biocatalytic and chemocatalytic C?H functionalization methods to prepare two key precursors to the natural product in an efficient and scalable manner. The success of our study highlights the benefits of applying the principles of biocatalytic retrosynthesis as well as C?H functionalization logic to the synthesis of complex molecular scaffolds. 相似文献