全文获取类型
收费全文 | 583篇 |
免费 | 33篇 |
国内免费 | 9篇 |
专业分类
化学 | 348篇 |
晶体学 | 5篇 |
力学 | 14篇 |
综合类 | 5篇 |
数学 | 83篇 |
物理学 | 170篇 |
出版年
2022年 | 9篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 17篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 53篇 |
2012年 | 34篇 |
2011年 | 27篇 |
2010年 | 18篇 |
2009年 | 32篇 |
2008年 | 32篇 |
2007年 | 25篇 |
2006年 | 12篇 |
2005年 | 16篇 |
2004年 | 25篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1971年 | 6篇 |
1923年 | 14篇 |
1905年 | 2篇 |
排序方式: 共有625条查询结果,搜索用时 15 毫秒
1.
D. Andrae U. Häußermann M. Dolg H. Stoll H. Preuß 《Theoretical chemistry accounts》1990,77(2):123-141
Summary Nonrelativistic and quasirelativisticab initio pseudopotentials substituting the Mup>(Z–28)+up>-core orbitals of the second row transition elements and the Mup>(Z–60)+up>-core orbitals of the third row transition elements, respectively, and optimized (8s7p6d)/[6s5p3d]-GTO valence basis sets for use in molecular calculations have been generated. Additionally, corresponding spin-orbit operators have also been derived. Atomic excitation and ionization energies from numerical HF as well as from SCF pseudopotential calculations using the derived basis sets differ in most cases by less than 0.1 eV from corresponding numerical all-electron results. Spin-orbit splittings for lowlying states are in reasonable agreement with corresponding all-electron Dirac-Fock (DF) results. 相似文献
2.
Yu. A. Simonov N. V. Gérbéléu P. N. Bourosh V. B. Arion A. D. Garnovskii A. N. Sobolev V. A. Alekseenko 《Journal of Structural Chemistry》1990,31(2):365-369
Institute for Applied Physics, Academy of Sciences of the Moldavian SSR. Institute of Chemistry, Academy of Sciences of the Moldavian SSR. Nat. Research Institute for Physics and Organic Chemistry, Rostov State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 2, pp. 199–202, 1990. 相似文献
3.
N. V. Gérbéléu V. B. Arion Yu. A. Simonov V. E. Zavodnik K. I. Turté S. S. Stavrov A. A. Pasynskii O. G. Ellert D. I. Grédinaru M. S. Byrke 《Theoretical and Experimental Chemistry》1991,27(3):327-332
Sodium acetylacetonate reacts with S-metliylisothiosemicarbazidium nitrate and Fe(NOub>3ub>)ub>3ub> · 9Hub>2ub>O in ethanol to make [Fe(HL)NO]NOub>3ub>, in which Hub>3ub>L is bis(S-methyl-isothiosemicarbazone)-2,4-puntandione. The [Fe(HL)NO]up>+up> cation has a square pyramidal structure with the HLup>2-up> arranged around the central ion in the basal plane and the nitrogen atom of the NO group in the apical position, with the iron atom diverging from the plane of the base of the pyramid by 0.477 Å. The FeN0 moiety has a linear structure (u/xxlarge8736.gif" alt="ang" align="BASELINE" BORDER="0">FeNO = l72.7°). XRD, IR, and Mössbauer spectroscopy have been combined with calculations on the electronic structure to demonstrate that the Fe-NO bond is covalent.Chemical Institute, Academy of Sciences of Moldavian SSR. Applied Physics Institute, Academy of Sciences of the Moldavian SSR. Kishinev. Institute of Crystallography, Academy of Sciences of the USSR. Kurnakov Institute for General and Inorganic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No, 3, pp. 376–381, May–June, 1991. Original article submitted February 18, 1991. 相似文献
4.
5.
M. A. Aramendia V. Boráu C. Jimenez J. M. Marinas 《Reaction Kinetics and Catalysis Letters》1981,18(3-4):335-339
The synthesis and physicochemical properties of new metallic systems obtained by supporting Pd on colloidal AlPOub>4ub>, AlPOub>4ub>–SiOub>2ub> and AlPOub>4ub>--Alub>2ub>Oub>3ub> to be used as reduction catalysts are reported. The catalytic activity of the above systems in the transfer reduction of nitrobenzene using cyclohexene as hydrogen donor has been measured.
uote>ucy" align="BASELINE" BORDER="0"> , ucy" align="MIDDLE" BORDER="0"> Pd AlPOub>4ub>, AlPOub>4ub>SiOub>2ub> AlPOub>4ub>-Alub>2ub>Oub>3ub> ucy" align="MIDDLE" BORDER="0"> . , ucy" align="MIDDLE" BORDER="0"> . uote> 相似文献
6.
Oren?Regev Jean-Fran?ois?Gohy Bas?G.?G.?Lohmeijer Sunil?K.?Varshney Dominique?H.?W.?Hubert Peter?M.?Frederik Ulrich?S.?SchubertEmail author 《Colloid and polymer science》2004,282(4):407-411
Metallo-supramolecular diblock copolymers consisting of a polystyrene (PS) block connected to a poly(ethylene oxide) (PEO) block by a bis(terpyridine)ruthenium complex (PSub>20ub>-[Ru]-PEOub>
y
ub>) were used to prepare aqueous micelles. The length of the PS block was kept constant, while two PEOs of different molecular weight were used. The resulting hydrated micelles and aggregates were characterized by a combination of cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering measurements. The results were compared to those obtained for a covalent counterpart (PSub>22ub>-b-PEOub>70ub>). Cryogenic transmission electron microscopy allowed visualization of the PS core of the micelles. Moreover, the aggregates result from clustering of individual micelles. 相似文献
7.
N. V. Gérbéléu K. M. Indrichan V. B. Arion 《Theoretical and Experimental Chemistry》1991,27(2):187-192
The mass spectra of the coordination compounds of nickel(II) with the bis-S-substituted thiosemicarbazones of 2,4-pentanedione (Rub>2ub>Hub>2ub>L) with the general formula [NiRub>2ub>HL]X and of 3-oxo-2,4-pentanedione (Hub>2ub>Rub>2ub>LO) with the general formula NiRub>2ub>LO were studied. A distinguishing feature of the mass spectra of [NiRub>2ub>HL]X is the absence of molecular ion peaks. The initial point of fragmentation is the [M - HX] ions. The strongest lines in spectra of NiRub>2ub>LO are those due to the elimination of R and R-H. At the first stage the fragmentation of all the investigated compounds takes place mainly through only one of the thiosemicarbazide residues. At the second stage the 2,4-pentanedione (3-oxo-2,4-pentanedione) residue is eliminated, after which the remaining thiosemicarbazide part dissociates. A significant part of the fragmentation paths was confirmed by the peaks of the metastable ions and also by the mass spectra of the deuterated analogs.Institute of Chemistry, Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 2, 205–211, March–April, 1991. Original article submitted August 19, 1986. 相似文献
8.
Michael Chariss Andrea Zickgraf Heike Stenger Elmar Bru Cristelle Desmarquet Martin Drger Silke Gerstmann Dainis Dakternieks James Hook 《Polyhedron》1998,17(25-26)
44 members of thecompound series Phub>4−nub>MRub>nub> (M=Si, Ge, Sn, Pb; R=o-, m-, p-Tol; n=0–4) were synthesized (15 newcompounds). The crystal structures of Phub>3ub>Sn (o-Tol) and PhSn (o-Tol)ub>3ub> were determined and compared to 16 known structures. Subject to the distanced (M–C), an interplay between through-space π–π repulsion and π–σ attraction leads to either elongated or compressed tetrahedral geometry. up>29up> Si-, up>119up> Sn- and up>207up> Pb-NMR chemical shifts were determined in solution and in the solid state. up>73up> Ge chemical shifts were measured only in solution. Anupfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a π–σcharge transfer which is constrained by torsion of the aromatic groups. 相似文献
9.
The effects of cubic potentials on discrete breathers in a mixed Klein-Gordon /Fermi-Pasta-Ulam chain 下载免费PDF全文
Nonlinearity has a crucial impact on the symmetry properties of dynamical
systems. This paper studies a one-dimensional mixed Klein--Gordon/Fermi--Pasta--Ulam diatomic
chain using the expanded rotating plane-wave approximation and numerical
calculations to determine the effect of cubic potentials on the symmetry
properties of discrete breathers in this system. The results will be very
useful to researchers in the field of numerical calculations on
discrete breathers. 相似文献
10.
Martin Danko Matej Mičušík Mária Omastová Juraj Bujdák Dušan Chorvát Jr. 《Chemical Papers》2014,68(11):1621-1622