全文获取类型
收费全文 | 12440篇 |
免费 | 1471篇 |
国内免费 | 2080篇 |
专业分类
化学 | 9898篇 |
晶体学 | 115篇 |
力学 | 295篇 |
综合类 | 73篇 |
数学 | 50篇 |
物理学 | 1936篇 |
综合类 | 3624篇 |
出版年
2024年 | 55篇 |
2023年 | 167篇 |
2022年 | 427篇 |
2021年 | 548篇 |
2020年 | 754篇 |
2019年 | 569篇 |
2018年 | 411篇 |
2017年 | 428篇 |
2016年 | 504篇 |
2015年 | 529篇 |
2014年 | 631篇 |
2013年 | 906篇 |
2012年 | 808篇 |
2011年 | 646篇 |
2010年 | 486篇 |
2009年 | 602篇 |
2008年 | 589篇 |
2007年 | 680篇 |
2006年 | 689篇 |
2005年 | 641篇 |
2004年 | 645篇 |
2003年 | 543篇 |
2002年 | 540篇 |
2001年 | 383篇 |
2000年 | 376篇 |
1999年 | 281篇 |
1998年 | 251篇 |
1997年 | 251篇 |
1996年 | 223篇 |
1995年 | 243篇 |
1994年 | 211篇 |
1993年 | 184篇 |
1992年 | 156篇 |
1991年 | 110篇 |
1990年 | 94篇 |
1989年 | 85篇 |
1988年 | 88篇 |
1987年 | 73篇 |
1986年 | 36篇 |
1985年 | 26篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 8篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
Immobilized sulfhydryl groups were prepared by partial thiolation of NH2-glass beads. The microenvironment of the immobilized SH groups was varied by different chemical modifications of neighboring
NH2 groups. Introduction of a strong charge in the surroundings of immobilized sulfhydryls results in their dramatic stabilization
against autooxidation. This effect is due to the salting of O2 from the surface microlayer of the thiolated beads. 相似文献
202.
A. V. Sinitsky M. B. Darhovskii A. L. Tchougreff I. A. Misurkin 《International journal of quantum chemistry》2002,88(4):370-379
In the present work the semiempirical effective crystal field (ECF) method previously designed for electronic structure calculations of transition metal complexes and utilizing non‐Hartree–Fock trial wave function and parameterized for complexes of doubly charged Cr2+, V2+, Mn2+, Fe2+, Co2+, and Ni2+ cations is extended to complexes of triply charged cations of 3d‐elements. With the parameters adjusted the ECF method is applied to calculations of ground states and low‐energy spectra of the d‐shells of fluoro‐, chloro‐, aqua‐, amino‐, and cyano‐complexes of the triply charged cations. Obtained total spin and symmetry of the ground states match the experimentally observed ones. Satisfactory agreement between the calculated and experimental d‐shell electronic transition energies is achieved as well. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
203.
本文对一类重要的ⅥB族金属叁键化合物R_2M_2(CO)_4(R为环戊二烯基及类环戊二烯基)近年来的研究成果进行了综述,综述重点是这类化合物的官能团M≡M参键的化学活性,全文包括R_2M_2(CO)_4的合成及结构,M≡M叁键与亲核试剂、与碳-碳重键,与氧或与金属羰基物等试剂的反应及其应用。 相似文献
204.
205.
206.
207.
Dynamical Behaviour of Linear Molecular Anions in the Hydrogensulfides of Sodium, Potassium and Rubidium: Differential Scanning Calorimetry, X-ray and Neutron Diffraction Hydrogensulfides of the alkali metals M ? Na, K, Rb were prepared in autoclaves by the reaction of the corresponding metals with H2S and D2S, respectively, in the temperature range from 50°C to 150°C. Differential scanning calorimetry, X-ray and neutron diffraction methods reveal that both, the HS?-and DS?-compounds occur in three crystalline modifications with HT ? high-, MT ? medium- and LT ? low-temperature form: The temperatures and enthalpies for the changes of modifications of the H- and D-compounds are given and the atomic arrangements revealed mainly by neutron diffraction data are discussed, in relation to, for example, size of cations. 相似文献
208.
A solution of metallic ytterbium in liquid ammonia reacts readily with various carbonyl complexes of metals to form the corresponding
lanthanide carbonylmetallates. The reaction of an excess of Yb in liquid NH3 with [CpFe(CO)2]2 gave (THF)4Yb[Fe(CO)2Cp]2 in 42% yield. It was suggested that the resulting complex contains two equivalent Yb−Fe bonds.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1883–1885, October, 1997. 相似文献
209.
The crystal habit of fcc metal particles formed on an amorphous carbon film electrode in solution at different electrode
potentials is discussed. The fcc metal particles have different crystallographic habits depending on applied electrode potential;
that is, icosahedral and/or decahedral particles are formed at lower potentials, and fcc single-crystalline or polycrystalline
particles at higher potentials. It was found that decahedra and icosahedra of Cu-Au alloy particles are formed in the potential
region of underpotential deposition (UPD) of Cu at which only fcc Au single-crystalline particles and Au polycrystalline particles
appear. This is attributed to the charge transfer from the UPD Cu ions to the Au overlayer of Cu-Au alloy particles. The formation
of decahedral and icosahedral Cu-Au alloy particles depends on the composition of the Cu-Au alloy. On the basis of these results
it was deduced that the contraction of the surface lattice of the growing particles is responsible for the formation of icosahedral
and decahedral particles.
Received: 25 February 1997 / Accepted: 21 April 1997 相似文献
210.
YAN Zi-Feng 《天然气化学杂志》1996,5(3):261-271
Introduction0ncofthcintriguingpr0blcmsinhctcrogcncouscatal}'sisisthcactit'ationanddircctconversionofmcthancintoliquidfucIanduscful.h..i..l,lllMcthancactivationisvcry'difficultbccauscn1cthancisathcrmod}'namicalI}'stablccompoundt`ithanoblcgas-likcconfigurati0nThcvcry'strongtctrahcdralC-Hbonds(435kJ/mol)offcrnofiJnctionalgroups,magncticm0mcnts'orpolardistortionstofacilitatcchcmicalattackThismakcsmcthanelcssrcactivcthanncarl}'allitsconvcrsionproducts.Rccentl}'oxidativccouplinghasbecnconsidcrcda… 相似文献