首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   191篇
  免费   0篇
数理化   191篇
  2022年   2篇
  2020年   10篇
  2019年   4篇
  2018年   7篇
  2017年   10篇
  2016年   7篇
  2015年   5篇
  2014年   5篇
  2013年   4篇
  2012年   5篇
  2011年   11篇
  2010年   6篇
  2009年   8篇
  2008年   5篇
  2007年   6篇
  2006年   8篇
  2005年   6篇
  2004年   1篇
  2003年   5篇
  2002年   8篇
  2001年   3篇
  2000年   5篇
  1999年   5篇
  1998年   5篇
  1997年   2篇
  1996年   3篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1990年   2篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1985年   3篇
  1984年   6篇
  1983年   4篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1975年   1篇
  1974年   1篇
  1973年   3篇
  1970年   1篇
  1966年   2篇
  1963年   1篇
  1960年   1篇
  1958年   1篇
  1954年   1篇
排序方式: 共有191条查询结果,搜索用时 15 毫秒
1.
A two-dimensional self consistent model of the Beam-Plasma-Discharge (BPD) has been developed to calculate the discharge ignition of a bandlike electron beam in a discharge chamber. The discharge was considered in Argon with an initial concentration of 1014 cm?3. The model allows calculation of the time evolution of perpendicular profiles of electron density, temperature and the potential.  相似文献   
2.
The reaction of dimethylsulfonium methylide with the carbonyl function of 2-arylidene-cyclohexanones obtained from 2-methylcyclohexanone affords the corresponding spirooxiranes. The application of this reaction to 2,2-dimethyl-6-(5-methylfurfurylidene)cyclohexanone and 2,2-dimethyl-6-(5-chlorofurfurylidene)cyclohexanone leads to substituted 4,4-dimethyl-1-furyl-1,-3,4,5,6,7-hexahydroisobenzofurans.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1439–1443, August, 1994.  相似文献   
3.
4.
Ring opening in 2-alkyl-4,5-dihydrooxazoles by the action of azoles gave intermediate N-(2-azolylethyl)alkanamides, whose hydrolysis afforded N-(2-aminoethyl)azoles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1781–1784, October, 2006.  相似文献   
5.
Glycine-nitrate combustion method was used to obtain nanopowders of orthorhombic and hexagonal yttrium orthoferrite with particles sizes in the ranges from 30 to 53 nm and from 6 to 14 nm, respectively. It is shown that the structure and size of the particles are determined by the process temperature, which depends on the relative amounts of glycine and nitrates in the initial mixture. It is shown that yttrium orthoferrite nanopowders with a certain crystal structure and particle size can be obtained by varying the glycine/nitrate ratio. The nanopowders and materials on their basis can be used as photocatalysts.  相似文献   
6.
7.
Russian Journal of Physical Chemistry A - The results are presented from quantum-chemical modeling of the chemisorption of atomic hydrogen and fluorine on the surface of a hexagonal boron nitride...  相似文献   
8.
In this communication the evaluation of eleven new metallocomplex alanine synthons bearing C2-symmetric benzyl groups with electron-donating and electron-withdrawing substituents is described. α-Methylated glycine synthons (alanine complexes) were evaluated alongside alanine synthons in order to obtain a deeper understanding of the relationship between their structures and stereochemistry of monoalkylated products and to choose several candidates for their further tests for stereospecific preparation of 6-[18F]FDOPA. Glycine-derived analogues of the complexes 3–5 are the best candidates for the development of a 6-[18F]FDOPA preparation procedure. In the model epimerisation reaction they demonstrated the best performance, much better compared to the previously described compound 2. Complexes 3, 5 and 8 are the best in asymmetric preparation of β-13C monolabelled α-aminoisobutyric acid. They have to be tested in the preparation of α-methyl amino acids like 6-[18F]-α-methylDOPA and 2-[18F]-α-methyltyrosine.  相似文献   
9.
A series of 1,3-disubstituted 4-benzylideneamino-5-thioxohexahydroimidazo[4,5-d]imidazol-2(1H)-ones (thioglycolurils) was synthesized via the reaction of 5,7-disubstituted 3-thioxoperhydroimidazo[4,5-e]-1,2,4-triazin-6-ones with hydroxy-, alkoxy-, and fluorocontaining benzaldehyde derivatives. An alkylation of the obtained thioglycolurils with methyl iodide or 4-bromobenzyl bromide provided the corresponding 6-benzylideneamino-5-alkylsulfanyl-3,3a,6,6a-tetrahydroimidazo[4,5-d]imidazol-2(1H)-ones. The fungicidal activity of some synthesized compounds against pathogens causing diseases of agricultural crops was studied.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号