首页 | 本学科首页   官方微博 | 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   37篇
  免费   0篇
化学   27篇
晶体学   1篇
物理学   9篇
  2021年   1篇
  2018年   1篇
  2017年   1篇
  2013年   1篇
  2011年   2篇
  2010年   2篇
  2009年   2篇
  2008年   2篇
  2007年   2篇
  2006年   3篇
  2005年   3篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  1998年   1篇
  1994年   1篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1976年   2篇
  1968年   1篇
排序方式: 共有37条查询结果,搜索用时 15 毫秒
1.
Chemistry of Heterocyclic Compounds - A series of functionalized 4,5,6,7-tetrahydroindol-4-one derivatives containing a residue derived from β-dicarbonyl compound at position 3 were prepared...  相似文献   
2.
3.
A new molecular semiconductor, (Doet)2ReO4(Doet is (1,4-dioxanediyl-2,3-dithio)ethylenedithiotetrathiafulvalene), is synthesized and examined by X-ray diffraction analysis. The crystal structure of (Doet)2ReO4is formed by [Doet]+1/2layers with isle [ReO4]anions located between them. The Doet radical cations from the adjacent layers are linked by intermolecular hydrogen interactions of the O···H type.  相似文献   
4.
5.
The -(BETS)2C(CN)3 radical cation salt was prepared by electrocrystallization, and its crystal structure was determined by single crystal X-ray diffraction. The electronic structure of -(BETS)2C(CN)3 was studied by means of the extended Hückel tight binding method. The electrical conductivity of this salt as a function of temperature shows a metallic behaviour down to 1.3 K. Shubnikov-de Haas oscillations reveal both the classical and magnetic breakdown orbits on the Fermi surface typical of the -type organic conductors. In addition, a low frequency oscillation (250 T) which is not predicted by the band structure calculations has been found in the oscillation spectrum. Received: 11 March 1998 / Revised: 9 June 1998 / Accepted: 11 June 1998  相似文献   
6.
The stable metal β″-(DOEO)2HSeO4 · H2O I) based on a new donor compound, 3,4-(1,4-dioxanediyl-2,3-dithio)-3′,4′-ethylenedioxo-2,5,2′,5′-tetrathiafulvalene] (DOEO), is synthesized and structurally characterized for the first time. The synthesis is performed by the electrocrystallization technique (direct current density j = 2 × 10?6 A/cm2). The crystals are triclinic, and the unit cell parameters are as follows: a = 5.495(1) Å, b = 9.715(2) Å, c = 16.878(3) Å, α = 83.52(3)°, β = 82.54(3)°, γ = 73.51(3)°, Z = 1, and space group \(P\bar 1\). The salt has a layered structure. The DOEO1/2+ radical cation layers are aligned parallel to the ab planes. The HSeO 4 ? · H2O solvated anions are located in channels along the a axis and are disordered over two positions near the center of symmetry (1/2 0 0) with a probability of 50%. The conductivity of the salt is equal to 300–400 Ω?1 cm?1 at room temperature and increases upon cooling to the boiling point of liquid helium (4.2 K) by a factor of 100–200 depending on the sample.  相似文献   
7.
In the present paper, the feasibility of constructing a model of elementary and particles based on the Poincaré model of the electron [1] is examined with allowance for schemes of particle decay. The muon and pion in stopped states are considered as spherical resonators for virtual neutrino quanta excited inside an elastic lepton shell; the number of these quanta is determined by the scheme of the corresponding particle decay. In the model, the muon differs from the electron by two additional quanta of the neutrino field. The e, , and masses are calculated with the help of a single parameter. The ratio of and e masses is about (6c/e 2)2/3, and the ratio of ° and e masses is (3/2)2/3. The calculated e, , and ° masses are in the 0.547:105.71:134.963 ratios, which is in good agreement with the available experimental data. The calculated electromagnetic radius of the charged pion (±) = 0.5f is close to that calculated from the experimental data. The neutrino mass e is found to be m( e ) 0.02 eV.  相似文献   
8.
New radical cation salts (BEDT-TTF)2[3,3′-Co(1,2-C2B9H11)2] (1), (BEDT-TTF)2[8-I-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] (2), (BMDT-TTF)[3,3′-Co(1,2-C2B9H11)2] (3) and (TMTSF)2[3,3′-Fe(1,2-C2B9H11)2] (4) were synthesized and their crystal structures and electrical conductivities were determined. Compound 4 is isostructural to the earlier reported Co analogue. All the radical cation salts synthesized are semiconductors.  相似文献   
9.
Crystals of a new radical-cation salt (DOEO)4[HgBr4] · TCE (I) (DOEO = (1,4-dioxanediyl-2,3-dithio)ethylenedioxotetrathiafulvalene, TCE = 1,1,2-trichloroethane) were synthesized by electrocrystallization method at constant current (i=5×10?6 A/cm2). Crystal structure was studied at room (293 K) and low (30 K) temperatures and was found to consist of the radical-cation layers alternating along the z-axis with tetrahedral HgBr 4 2? anions and TCE molecules. The anion is disordered over three positions at room and over two positions at low temperatures with occupancy factors 87, 11, 2 and 98, 2%, respectively. The poorly occupied positions of the anion are overlapped with positions of the TCE molecule disordered over two equally occupied positions. The DOEO ethylene groups disordered at 293 K were found ordered at 30 K. The conductivity of I exhibits the following peculiarity: in a temperature interval of 120–140 K, the temperature dependence of resistivity has a pronounced maximum.  相似文献   
10.
New molecular conductors on the base of 8,8′-diiodo cobalt bis(dicarbollide) anion (TTF)[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (1), (BMDT-TTF)4[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (2) and (BEDT-TTF)2[8,8′-I2-3,3′-Co(1,2-C2B9H10)2] (3) were synthesized and their crystal structures and electrical conductivities were determined. All the radical cation salts prepared were found to be semiconductors. Some regularities in the crystal structures of the TTF-based radical cation salts with bis(dicarbollide) complexes of transition metals are discussed.  相似文献   
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