全文获取类型
收费全文 | 1376篇 |
免费 | 25篇 |
国内免费 | 39篇 |
专业分类
化学 | 778篇 |
晶体学 | 16篇 |
力学 | 155篇 |
综合类 | 6篇 |
数学 | 278篇 |
物理学 | 207篇 |
出版年
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 38篇 |
2014年 | 25篇 |
2013年 | 71篇 |
2012年 | 59篇 |
2011年 | 81篇 |
2010年 | 80篇 |
2009年 | 99篇 |
2008年 | 78篇 |
2007年 | 93篇 |
2006年 | 70篇 |
2005年 | 43篇 |
2004年 | 51篇 |
2003年 | 42篇 |
2002年 | 83篇 |
2001年 | 41篇 |
2000年 | 45篇 |
1999年 | 31篇 |
1998年 | 38篇 |
1997年 | 34篇 |
1996年 | 27篇 |
1995年 | 36篇 |
1994年 | 26篇 |
1993年 | 22篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1440条查询结果,搜索用时 15 毫秒
71.
《Physics and Chemistry of Liquids》2012,50(4):419-423
Bubble temperatures at 94.7?kPa, for the binary mixtures formed by methylethylketone (MEK) with cyclo-hexanone, tetrahydrofuran, ortho- and meta-xylenes, bromobenzene, chlorobenzene, epichlorohydrin, nitrobenzene, and iso- and tert-butanols have been measured by means of a Swietoslawski-type ebulliometer. The data could be represented well by the Wilson model. 相似文献
72.
73.
The Ruddlesden–Popper phases of the Ca–Ti–O system, Can+1TinO3n+1, are investigated by means of atomistic simulations employing empirical pair potentials. The stability of the phases is examined in terms of various reaction schemes: the formation from the binary oxides, the addition of the perovskite oxide to a given phase, and the reaction between perovskite and rock-salt oxides. The energies of these reactions are compared with results previously obtained for the Ruddlesden–Popper phases of the Sr–Ti–O system. The importance of the disproportionation reaction of the various R–P phases in both Ca and Sr systems is also emphasized. The results obtained are in good agreement with experimental observations regarding both systems. 相似文献
74.
Thorsten Will Michael C. Hutter Johann Jauch Volkhard Helms 《Journal of computational chemistry》2013,34(28):2485-2492
Besides all their conformational degrees of freedom, drug‐like molecules and natural products often also undergo tautomeric interconversions. Compared to the huge efforts made in experimental investigation of tautomerism, open and free algorithmic solutions for prototropic tautomer generation are surprisingly rare. The few freely available software packages limit their output to a subset of the possible configurational space by sometimes unwanted prior assumptions and complete neglection of ring‐chain tautomerism. Here, we describe an adjustable fully automatic tautomer enumeration approach, which is freely available and also incorporates the detection of ring‐chain variants. The algorithm is implemented in the MolTPC framework and accessible on SourceForge. © 2013 Wiley Periodicals, Inc. 相似文献
75.
Stig E. Friberg 《Journal of Dispersion Science and Technology》2013,34(2):207-212
The evaporation paths in a system of three single‐compound phases in equilibrium were calculated using a phase diagram approach assuming the evaporation rate proportional to the compound's vapor pressure and molecular weight. The variation with time of the weight of the individual phases was linear, while the weight fraction was not. The approach allowed a simple calculation of the fraction of remaining compounds after one of them was exhausted during the evaporation and a convenient graphical illustration of the importance of the relative vapor pressures. 相似文献
76.
Abeer Al-Bawab Ayat Bozeya Stig E. Friberg Patricis A. Aiken 《Journal of Dispersion Science and Technology》2013,34(5):606-610
The phase diagram of fragrance oil, geranyl acetate, water, and a surfactant, Laureth 4, was used to calculate the surfactant association structures present in emulsions with constant O/W ratio for increased fractions of surfactant. The liquid crystal appeared in the emulsion at a critical value of the surfactant fraction and additional surfactant caused an approximately linear increase of it, while the fraction of the aqueous phase experienced a corresponding reduction. The result of the calculations was confirmed by optical microscopy observation with the samples between crossed polarizers. The calculations revealed the formation of vesicles from the liquid crystal to result in a drastic reduction of the “free” aqueous phase, due to the amount of the aqueous liquid forming the core of the vesicle. 相似文献
77.
Prof. Giuseppe Alibrandi Dr. Valeria Amendola Dr. Greta Bergamaschi Dr. Riccardo Dollenz Prof. Luigi Fabbrizzi Prof. Maurizio Licchelli Dr. Carmelo Lo Vecchio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3729-3734
The combined activity of the 1.1.1‐cryptand and of a dicopper(II) bistren cryptate complex including chloride makes the Cl? ion be continuously and slowly delivered to the solution, without any external intervention. The 1.1.1‐cryptand slowly releases OH? ions, according to a defined kinetics, and each OH? ion displaces a Cl? ion from the cryptate. Chloride displacement induces a sharp colour change from bright yellow to aquamarine and can be conveniently monitored spectrophotometrically, even in diluted solutions. The 1.1.1‐cryptand is the motor of a molecular dispenser (the dicopper(II) cryptate) delivering chloride ion automatically, from the inside of the solution. 相似文献
78.
Characteristic properties of elastomers can be tailored by embedding them with filler particles. Along with enhancing the overall properties of the composite, filler particles also induce some inelastic effects. In this paper, a finite element computational model is used to study the effect of microstructure morphology in filled elastomers, on its macroscopic large deformation behavior. A multiphase material model that accounts for the hypothesis of shift in glass transition temperature in the vicinity of the filler particle is developed to simulate the interphase between the fillers and the matrix. It also accounts for the breakdown and re-aggregation of filler networks under cyclic loading. Examples at the microstructural level, demonstrating the dynamics of the interphase using the developed multiphase model have been successfully simulated. The obtained results are in good qualitative agreement with the Mullins effect. Therefore, computational experiments using this methodology enable the prediction of the experimentally observed softening behavior in filled elastomers based on its microstructure evolution. 相似文献
79.
Sven Ole Jaeschke Prof. Thisbe K. Lindhorst Prof. Alexander Auer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(56):e202201544
The conformational properties of monosaccharides constitute fundamental features of oligosaccharides. While the energy landscape of monosaccharides can be altered by a specific biochemical environment or by chemical modifications, the analysis of resulting dynamic conformational equilibria is not feasible by experimental means alone. In this work, a series of β-d -xylopyranosides is used to outline how a combination of experimental NMR parameters and computed molecular properties can be used to determine conformers and quantify the composition of conformational equilibria. We demonstrate that identifying the most stable conformers using energy calculations is challenging and computing of NMR shieldings is typically not sensitive enough. On the other hand, computed spin-spin coupling constants for the xyloside ring can be used to unambiguously assign experimental NMR data of dynamic conformational equilibria and quantify the ratio of different conformers in the mixture. As a proof of principle, this procedure allowed to analyze a hitherto unknown dynamic equilibrium of a diamino-xyloside as a precursor of a molecular switch. 相似文献
80.
We compare extensive experimental results for the
gravity-driven steady drainage of oil-in-water emulsions with two
theoretical predictions, both based on the assumption of Poiseuille flow.
The first is from standard foam drainage theory,
applicable at low aqueous volume fractions, for which a
correction is derived to account for the effects
of the confinement of the emulsion. The second arises
from considering the permeability of a model porous
medium consisting of solid sphere packings, applicable
at higher aqueous volume fractions. We find quantitative
agreement between experiment and the foam drainage theory at low
aqueous volume fractions. At higher aqueous volume
fractions, the reduced flow rate calculated from the
permeability theory approaches the master curve
of the experimental data. Our experimental data
demonstrates the analogy between the problem of electrical flow and liquid
flow through foams and emulsions. 相似文献