全文获取类型
收费全文 | 14193篇 |
免费 | 541篇 |
国内免费 | 84篇 |
专业分类
化学 | 10054篇 |
晶体学 | 131篇 |
力学 | 476篇 |
综合类 | 2篇 |
数学 | 1804篇 |
物理学 | 2351篇 |
出版年
2023年 | 81篇 |
2022年 | 106篇 |
2021年 | 140篇 |
2020年 | 221篇 |
2019年 | 224篇 |
2018年 | 257篇 |
2017年 | 197篇 |
2016年 | 433篇 |
2015年 | 344篇 |
2014年 | 368篇 |
2013年 | 833篇 |
2012年 | 897篇 |
2011年 | 1086篇 |
2010年 | 551篇 |
2009年 | 469篇 |
2008年 | 930篇 |
2007年 | 992篇 |
2006年 | 928篇 |
2005年 | 883篇 |
2004年 | 742篇 |
2003年 | 644篇 |
2002年 | 538篇 |
2001年 | 227篇 |
2000年 | 162篇 |
1999年 | 158篇 |
1998年 | 138篇 |
1997年 | 111篇 |
1996年 | 162篇 |
1995年 | 123篇 |
1994年 | 118篇 |
1993年 | 112篇 |
1992年 | 95篇 |
1991年 | 85篇 |
1990年 | 72篇 |
1989年 | 70篇 |
1988年 | 52篇 |
1987年 | 57篇 |
1986年 | 45篇 |
1985年 | 110篇 |
1984年 | 101篇 |
1983年 | 71篇 |
1982年 | 100篇 |
1981年 | 91篇 |
1980年 | 91篇 |
1979年 | 84篇 |
1978年 | 80篇 |
1977年 | 71篇 |
1976年 | 82篇 |
1975年 | 63篇 |
1974年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Alam MS Katayama N Kim IJ Li WC Lou XC Sun CR Bortoletto D Goldberg M Horwitz N Mestayer MD Moneti GC Sharma V Shipsey IP Skwarnicki T Csorna SE Letson T Brock IC Ferguson T Artuso M Bebek C Berkelman K Blucher E Byrd J Cassel DG Cheu E Coffman DM Crawford G DeSalvo R DeWire JW Drell PS Ehrlich R Galik RS Gittelman B Gray SW Halling AM Hartill DL Heltsley BK Kandaswamy J Kowalewski R Kreinick DL Kubota Y Lewis JD Mistry NB Mueller J Namjoshi R Nandi S Nordberg E O'Grady C Peterson D Pisharody M 《Physical review D: Particles and fields》1989,40(11):3790
82.
Carbon Nanotubes in Analytical Sciences 总被引:1,自引:0,他引:1
Arben Merkoçi 《Mikrochimica acta》2006,152(3-4):157-174
83.
In order to better understand the early continental evolution of the Anshan area, one ofthe typical Precambrian distribution areas of the North China Craton, the geochronology and REEcomposition of the zircons from the meta-argillo-arenaceous rock occurred as enclave in 3.1 GaLishan trondhjemite are studied by using SHRIMP ll ion microprobe. It is indicated that the Pa-leoarchaean is a very important continental formation period in the Anshan area and 3.2 Ga can beregarded as the boundary between the Paleoarchaean and Mesoarchaean. 相似文献
84.
Sabbe MK Saeys M Reyniers MF Marin GB Van Speybroeck V Waroquier M 《The journal of physical chemistry. A》2005,109(33):7466-7480
A complete and consistent set of 95 Benson group additive values (GAV) for the standard enthalpy of formation of hydrocarbons and hydrocarbon radicals at 298 K and 1 bar is derived from an extensive and accurate database of 233 ab initio standard enthalpies of formation, calculated at the CBS-QB3 level of theory. The accuracy of the database was further improved by adding newly determined bond additive corrections (BAC) to the CBS-QB3 enthalpies. The mean absolute deviation (MAD) for a training set of 51 hydrocarbons is better than 2 kJ mol(-1). GAVs for 16 hydrocarbon groups, i.e., C(C(d))(3)(C), C-(C(d))(4), C-(C(t))(C(d))(C)(2), C-(C(t))(C(d))(2)(C), C-(C(t))(C(d))(3), C-(C(t))(2)(C)(2), C-(C(t))(2)(C(d))(C), C-(C(t))(2)(C(d))(2), C-(C(t))(3)(C), C-(C(t))(3)(C(d)), C-(C(t))(4), C-(C(b))(C(d))(C)(H), C-(C(b))(C(t))(H)(2), C-(C(b))(C(t))(C)(H), C-(C(b))(C(t))(C)(2), C(d)-(C(b))(C(t)), for 25 hydrocarbon radical groups, and several ring strain corrections (RSC) are determined for the first time. The new parameters significantly extend the applicability of Benson's group additivity method. The extensive database allowed an evaluation of previously proposed methods to account for non-next-nearest neighbor interactions (NNI). Here, a novel consistent scheme is proposed to account for NNIs in radicals. In addition, hydrogen bond increments (HBI) are determined for the calculation of radical standard enthalpies of formation. In particular for resonance stabilized radicals, the HBI method provides an improvement over Benson's group additivity method. 相似文献
85.
Kelley BD Booth J Tannatt M Wub QL Ladner R Yuc J Potter D Ley A 《Journal of chromatography. A》2004,1038(1-2):121-130
Polypeptides for use in affinity chromatography of factor VIII were identified using phage display technology. Phage libraries were designed to express polypeptide fusions containing five to seven residues flanked by two cysteines that form a disulfide bond. Individual bacteriophage were selected for the ability of these polypeptides to bind factor VIII, and then release the protein under mild elution conditions. Strong consensus sequences were observed that appear to be necessary for this reversible interaction. Chemically synthesized ligands identified by this screening were immobilized onto a chromatographic support and used for affinity purification of factor VIII from a complex feedstream. A chromatographic step was developed that provided a 10000-fold reduction in host cell proteins and DNA, while providing exceptional product recovery. 相似文献
86.
87.
Eric Cancès Renaud Keriven François Lodier Andreas Savin 《Theoretical chemistry accounts》2004,111(2-6):373-380
Efficient formulas for computing the probabilities of finding exactly electrons in an arbitrarily chosen volume 3 for Hartree–Fock wavefunctions are presented. These formulas allow the use of shape optimization techniques, such as level set methods, for optimizing with respect to various criteria involving such probabilities. The criterion defined as the difference between the Hartree–Fock and the independent-particle model probabilities of finding electrons in stresses the quantum effects due to the Pauli principle. We have implemented a 2D level set method for optimizing this criterion in order to study spatial separation of electron pairs in linear molecules. The method is described and the illustrative example of the BH molecule is reported.Contribution to the Jacopo Tomasi Honorary Issue 相似文献
88.
Applied Biochemistry and Biotechnology - Methods of achieving high-yield fermentation ofd-xylose to ethanol in shake flasks were investigated using the microaerophilic yeastPichia stipitis NRRL... 相似文献
89.
A highly flexible method for direct and quantitative determination of surface Br?nsted acidity of solids in terms of number, type and strength of the acid sites based on quantitative H/D exchange kinetics between the acid solid and gaseous D2O has been developed and applied to materials covering the whole range of acidity. 相似文献
90.
Brian D. Hudson Ashley R. George Martyn G. Ford David J. Livingstone 《Journal of computer-aided molecular design》1992,6(2):191-201
Summary Molecular dynamics simulations have been performed on a number of conformationally flexible pyrethroid insecticides. The results indicate that molecular dynamics is a suitable tool for conformational searching of small molecules given suitable simulation parameters. The structures derived from the simulations are compared with the static conformation used in a previous study. Various physicochemical parameters have been calculated for a set of conformations selected from the simulations using multivariate analysis. The averaged values of the parameters over the selected set (and the factors derived from them) are compared with the single conformation values used in the previous study. 相似文献