全文获取类型
收费全文 | 235篇 |
免费 | 0篇 |
专业分类
化学 | 120篇 |
晶体学 | 68篇 |
力学 | 2篇 |
数学 | 15篇 |
物理学 | 30篇 |
出版年
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 17篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 15篇 |
2007年 | 8篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有235条查询结果,搜索用时 15 毫秒
31.
32.
The activation of the catalytic persulphate oxidation of sulphanilic acid when the catalyst, silver(I), is suitably complexed, is discussed. 2,2'-Bipyridyl is proposed as activator as it accelerates the rate-determining step of the process-the oxidation of silver(I) to silver(II). The mechanism of activation is investigated and discussed in detail. On the basis of these investigations a catalytic method has been developed for the determination of silver(I), with a sensitivity of 4 x 10(-4)mug ml and +/-7.6% relative error. 相似文献
33.
Yordanov ND Dimitrova A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(4):826-829
EPR study on the ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II), Cu(Et2dsc)2, and bis(octyldithiocarbonato)copper(II), Cu(octxant)2, in CH2Cl2, CHCl3, CCl4, C6H6 and C6H5.CH3 is reported for the first time. Mixing of equimolar amounts of the parents (chromophores CuSe4 and CuS4, respectively) in C6H6, C6H5.CH3 and CH2Cl2 makes EPR signals of both parents superimposed by the spectrum of a mixed-chelate Cu(xant)(dsc) complex (chromophore CuS2Se2). A new additional EPR spectrum appears in CHCl3 or CCl4 due to a five-coordinate mixed-ligand complex with the chromophore Cu(S3Se)S as follows by comparing the g-values of parents and mixed-ligand complexes. The appearance of this complex could be explained having in mind donor-acceptor properties of complexes, solvents and the resultant reaction of Cu(octxant)2 with the ester of diselenocarbamic acid yielded in Cu(Et2dsc)2 destruction by CCl4 or CHCl3. 相似文献
34.
We search for traveling-wave solutions of the class of PDEswhere Ap(Q),Br(Q),Cs(Q),Du(Q) and F(Q) are polynomials of Q. The basis of the investigation is a modification of the method of simplest equation. The equations of Bernoulli, Riccati and the extended tanh-function equation are used as simplest equations. The obtained general results are illustrated by obtaining exact solutions of versions of the generalized Kuramoto-Sivashinsky equation, reaction-diffusion equation with density-dependent diffusion, and the reaction-telegraph equation. 相似文献
35.
Crystals of a new rare-earth chain diborate TmH[B2O5], space group C2/c, are obtained under hydrothermal conditions. The structure is determined without preliminary knowledge of the chemical formula. It is close to that of the GdH[B2O5] diborate studied earlier, but has a different orientation of the monoclinicity axis. In both structures the arrangement of atoms follows the pattern of the orthorhombic pseudosupergroup Cmca, which is most distinctly violated by the displacements of the rare-earth atoms. Their common anionic chain radical consists of diborate groups, namely, BO3 triangles and BO4 tetrahedra, 2[1T + 1Δ]. It is shown that the existence of two varieties that are based on the hypothetical orthorhombic prototype is determined by the pseudosymmetry and the difference between the ionic radii of the elements located at the middle and the end of the rare-earth series. The twinning and poor quality of the crystals are related to the effect of the m pseudoplane of the supergroup and cleavage. The structures of natural megaborates that contain diborate chains in complex boron-oxygen radicals are discussed. 相似文献
36.
O. A. Gurbanova A. G. Ivanova E. L. Belokoneva O. V. Dimitrova N. N. Mochenova 《Crystallography Reports》2008,53(1):47-52
New iodates, namely, In(IO3)3 (space group R \(\bar 3\)) and Sm(IO3)3 (space group P21/a), are synthesized under hydrothermal conditions. The original crystal structure of the In(IO3)3 compound is determined without prior knowledge of the chemical formula. The Sm(IO3)3 compound is isostructural to the Gd(IO3)3 compound. The [IO4]3- tetrahedra with three short I-O bonds have an umbrella coordination, which is characteristic of pentavalent iodine, and form anionic radicals, such as a ring radical in the In(IO3)3 iodate, a triple helix in the isoformula compound Fe(IO3)3, a complex chain in the Sm(IO3)3 iodate, and a linear triortho group in the Sm(IO3)3·H2O compound. All radicals contain triortho groups. The structural differences are determined by different ionic radii and shapes of the coordination polyhedra of the cations (indium and iron octahedra and an eight-vertex samarium polyhedron). 相似文献
37.
The crystal structure of a new synthetic aluminophosphate {[Rb1.94(H2O,OH)3.84](H2O)0.1}{Al4(OH)4[PO4]3} synthesized under mild hydrothermal conditions (T = 280°C, P = 100 atm) in the Rb2O-Al2O3-P2O5-H2O system is determined using X-ray diffraction (Stoe IPDS diffractometer, λMoK
α, graphite monochromator, 2θmax = 64.33°, R = 0.032 for 312 reflections). The main crystal data are as follows: a = 7.4931(6) ?, space group P
3m, Z = 1, and ρcalcd = 2.76 g/cm3. It is shown that the synthesized compound belongs to the pharmacosiderite structure type with a characteristic mixed open
microporous framework composed of octahedra and tetrahedra. A comparative crystal chemical analysis of related phases is performed,
and the chemical compositions of promising absorbents, i.e., hypothetical compounds potentially possible in the structure
type under consideration, are proposed. It is established that pharmacosiderite and rhodizite are homeotypic to each other.
Original Russian Text ? O.V. Yakubovich, W. Massa, O.V. Dimitrova, 2008, published in Kristallografiya, 2008, Vol. 53, No.
3, pp. 442–449. 相似文献
38.
N. D. Gavrilova O. V. Dimitrova A. M. Lotonov N. N. Mochenova V. K. Novik 《Moscow University Physics Bulletin》2008,63(2):127-131
The dispersion of permittivity and conductivity of crystals containing aqua complexes of different types (γ-HBO2, Ca2B6O11 · H2O, La[B5O8]OH)2 · 1.5H2O, and TRB6O9(OH)3(TR-Tb, Tu)) is studied for the first time. The compounds were synthesized under hydrothermal conditions at T = 270–280°C and P = 70–100 atm. Depending on the contained aqua complex, the compounds display different temperature and frequency behavior of the electric properties. The measurements are carried out in the frequency range from 10?2 to 106 Hz and in the temperature range from ?20 to 140°C. 相似文献
39.
40.
Krzysztof Bartkowski Maria Dimitrova Prof. Piotr J. Chmielewski Prof. Dage Sundholm Dr. Miłosz Pawlicki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15477-15482
Understanding of the aromatic properties and magnetically induced current densities of highly conjugated chromophores is important when designing molecules with strongly delocalized electronic structure. Linear extension of the triphyrin(2.1.1) skeleton with an annelated benzo[b]heterocycle fragment modifies the aromatic character by extending the electron delocalization pathway. Two-electron reduction leads to an antiaromatic triphyrin(2.1.1) ring and an aromatic benzo[b]heterocycle subunit. Current-density calculations provide detailed information about the observed pathways and their strengths. 相似文献