全文获取类型
收费全文 | 809篇 |
免费 | 19篇 |
国内免费 | 95篇 |
专业分类
化学 | 593篇 |
晶体学 | 15篇 |
力学 | 66篇 |
数学 | 12篇 |
物理学 | 237篇 |
出版年
2023年 | 9篇 |
2022年 | 16篇 |
2021年 | 7篇 |
2020年 | 18篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 25篇 |
2015年 | 40篇 |
2014年 | 19篇 |
2013年 | 30篇 |
2012年 | 39篇 |
2011年 | 47篇 |
2010年 | 37篇 |
2009年 | 68篇 |
2008年 | 53篇 |
2007年 | 58篇 |
2006年 | 52篇 |
2005年 | 43篇 |
2004年 | 45篇 |
2003年 | 28篇 |
2002年 | 27篇 |
2001年 | 25篇 |
2000年 | 30篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有923条查询结果,搜索用时 171 毫秒
101.
Calculation of the thermodynamic properties of biomolecules at high temperatures and pressures is fundamental to understanding the energetics of metabolism in hydrothermal systems. Perhaps the most direct interaction between hyperthermophilic microbes and their aquatic and mineralogic habitat involves conversion of environmentally available redox potential into biochemically useful energy. Although chemical thermodynamics can be used to quantify this process, little is known about the thermodynamic properties of the biomolecules involved, especially at high temperatures. However, recent advances in theoretical biogeochemistry make it possible to calculate these properties using the limited experimental data available in the literature, together with group additivity and correlation algorithms, reference model compounds and reactions, and the revised-HKF equations of state. This approach permits calculation of the standard molal thermodynamic properties and equations of state parameters for magnesium-complexed adenosine nucleotides, nicotinamide adenine dinucleotides (NADs), and nicotinamide adenine dinucleotide phosphates (NADPs) as a function of pressure and temperature. The thermodynamic properties and revised-HKF equations of state parameters generated in the present study can be used to carry out comprehensive mass transfer and Gibbs energy calculations to quantify the energetics of microbial energy production in hydrothermal systems. 相似文献
102.
James O. Jensen Pallassana N. Krishnan Luke A. Burke 《Journal of Molecular Structure》1996,370(2-3):245-252
Twenty-two structures with the empirical formula H3CNO are presented. These structures are examined since they have the same formula as the H2O…HCN complex. The H2O…HCN potential energy surface is of interest to chemists studying the water catalyzed polymerization of HCN. Structures, thermodynamics, and vibrational spectra are examined. 相似文献
103.
WANG Jingping LI Zhixia ZHANG Gencheng FEI Zhenghao TANG Shuhe Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources Environmental Protection Yancheng China The department of Yancheng Teachers College Yancheng China 《Chinese Journal of Reactive Polymers》2006,(2)
1. INTRODUCTION Chlorophenolic compounds are very toxic, and many are known or suspected human carcinogens. They have been widely used for many industrial purposes. The removals of chlorophenols are of high industrial and environmental interest [1~2]. The adsorption resin is another adsorbent widely employed for isolation and purification of organic substances, treatment of wastewaters, solid phase extraction, and so on. A variety of materials has been developed and tested, such as Amber… 相似文献
104.
Caroline Antion 《Surface science》2007,601(10):2232-2244
Energetics and chemistry of liquid surfaces and liquid/liquid interfaces of binary A-B alloys are calculated using a subregular solution model. In this model, two macroscopic energetic parameters are used to produce an asymmetric miscibility gap. They are related to two microscopic parameters which describe the interaction energy between two atoms as a function of the composition of the first coordination shell of each atom. The impact of the asymmetry of the A-B interactions on the surface and interfacial energies and adsorption are analyzed by comparing the results obtained with this subregular model to those calculated for a regular solution. The role of the asymmetry on the prewetting and wetting transitions are also discussed. Calculations performed in the Co-Cu system are in good agreement with experimental data of surface energy. 相似文献
105.
José M. Goenaga Ana Gayol Raquel G. Concha Miguel Iglesias José M. Resa 《Monatshefte für Chemie / Chemical Monthly》2007,138(5):403-436
Summary. Speeds of sound, densities, and refractive indices of the binary mixtures containing ethanol+(2-methyl-1-propanol, 2-methyl-1-butanol,
1-pentanol, or 3-methyl-1-butanol) were measured at 288.15 ≤ T/K ≤ 323.15 and atmospheric condition in the whole compositional range. The effect of temperature was analyzed by several
chemical terms. 相似文献
106.
Adela Kotočová 《Monatshefte für Chemie / Chemical Monthly》1992,123(8-9):709-711
Summary The half-wave potentials of the redox system [Co(en)3]3+/[Co(en)3]2+ have been influenced by the tetraalkylamonium cation of the supporting electrolyte used. This was explained with the specific interactions (solvation) of the tetraalkylamonium ion with the nonaqueous solvent.
Einfluß von Tetraalkylammoniumionen auf die Struktur nichtwäßriger Lösungsmittel (Kurze Mitt.)
Zusammenfassung Das Halbwellenpotential des Redoxsystems [Co(en)3]3+/[Co(en)3]2+ wird von Tetraalkylammonium-Ionen des Stützelektrolyten beeinflußt. Dies wird durch die spezifischen Wechselwirkungen (Solvatation) der Ionen mit dem nichtwäßrigen Lösungsmittel erklärt.相似文献
107.
Mahmoud Rajabian Charles Dubois Miroslav Grmela Pierre J. Carreau 《Rheologica Acta》2008,47(7):701-717
Rheological properties of suspensions of fibers in polymeric fluids are influenced by fiber–polymer interactions. In this
paper, we investigate this influence from both experimental and modeling standpoints. In the experimental part of this investigation,
we have changed the fiber–polymer interactions by treating the surface of the fibers. The resulting effects are observed using
scanning electron microscopy and dynamic mechanical analysis techniques and quantified from the measurements of the viscosity
in the start-up of shear flows and dynamic tests in the linear viscoelastic range region. The results are interpreted with
the help of a mesoscopic rheological model developed for suspensions of fibers in viscoelastic fluids. 相似文献
108.
J. Prost J.-B. Manneville R. Bruinsma 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):465-480
Membranes in thermal equilibrium are well known to exhibit Brownian motion type shape fluctuations. Membranes containing active
force centers -- such as chemically active membrane proteins -- suffer additional non-equilibrium shape fluctuations due to
the activity of these force centers. We demonstrate, using scaling arguments, that non-equilibrium shape fluctuations are
in general greatly amplified by the presence of a nearby wall or membrane due to the absence of a fluctuation-dissipation
theorem. For adhesive membranes, this fluctuation magnification effect may facilitate the establishment of bonding. For non-adhesive
membranes, fluctuation magnification produces a long-range repulsive pressure which can exceed the well known Helfrich repulsion
due to purely thermal fluctuations.
Received: 1 September 1997 / Accepted: 3 December 1997 相似文献
109.
Summary Relationships derived from the thermodynamic formulation of TLC with a binary mobile phase are discussed. The adsorption equilibrium
constant is determined from the linear form of a basic equation considering the adsorption process. This linear relationship
is examined with help of TLC data obtained by using six different chromatographic systems. The adsorption equilibrium constant
obtained from the TLC data is compared to the equilibrium constant determined from adsorption measurements.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
110.
Densities of water—glycol (mono- di-, tri- and tetraethyleneglycol) mixtures have been measured over the entire composition range at 298. 15 K. Mixtures involving monoethyleneglycol (MEG) have also been studied at different temperatures from 308.15 to 288.15 K. Deviations, VE, from ideal volumes of mixing have been calculated: negative values are observed for all systems. They increase with the number of ether functions present in the organic molecule; a slight dependence of VE towards temperature has been shown in the water—MEG mixtures. Partial molal volumes have also been calculated for both components of each system; they exhibit an extremum in the water-rich region. 相似文献