全文获取类型
收费全文 | 272篇 |
免费 | 9篇 |
国内免费 | 46篇 |
专业分类
化学 | 308篇 |
晶体学 | 7篇 |
综合类 | 1篇 |
物理学 | 11篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 18篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 13篇 |
2002年 | 85篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有327条查询结果,搜索用时 296 毫秒
31.
Oliwia M. Szklarczyk Eirini Arvaniti Wilfred F. van Gunsteren 《Journal of computational chemistry》2015,36(17):1311-1321
Force field parameters for polarizable coarse‐grained (CG) supra‐atomic models of liquid cyclohexane are proposed. Two different bead sizes were investigated, one representing two fine‐grained (FG) CH2r united atoms of the cyclohexane ring, and one representing three FG CH2r united atoms. Electronic polarizability is represented by a massless charge‐on‐spring particle connected to each CG bead. The model parameters were calibrated against the experimental density and heat of vaporization of liquid cyclohexane, and the free energy of cyclohexane hydration. Both models show good agreement with thermodynamic properties of cyclohexane, yet overestimate the self‐diffusion. The dielectric properties of the polarizable models agree very well with experiment. © 2015 Wiley Periodicals, Inc. 相似文献
32.
P(AA-MA)copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis.These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation.The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail.For the random copolymers,the permeate flux decreased rapidly with the increasing of molecular weight.The separation factor was also influenced by the molecular weight,which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight.Contrarily,the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/(m~2h)to 50 wt%benzene/cyclohexane mixture. 相似文献
33.
Vasina T. V. Masloboishchikova O. V. Khelkovskaya-Sergeeva E. G. Kustov L. M. Zeuthen P. 《Russian Chemical Bulletin》2002,51(2):255-258
The activity of monometallic Rh and Pt catalysts and bimetallic Pt—Rh catalysts on oxide supports in cyclohexane ring opening to form n-hexane was studied. The Rh-containing catalysts are highly active and selective in this reaction. Cyclohexane dehydrogenation predominates in the case of the Pt catalysts. The use of the bimetallic alumina-supported Pt—Rh catalysts allows one to minimize the contribution of cyclohexane cracking and to enhance the selectivity for n-hexane with the yield of the latter slightly depending on the metal ratio in the bimetallic system under the experimental conditions. 相似文献
34.
Vapor liquid equilibrium (VLE) is successfully predicted from excess enthalpy HE data for binary ether + n-alkane or cyclohexane mixtures. Parameters for the continuous linear association model (CLAM) and for the UNIQUAC Model for the excess Gibbs energy GE were determined from HE data measured at a low temperature (ambient temperature). These parameters are used to predict VLE data at low and high temperatures. The dependence of the accuracy of predictions on the set of HE data chosen to evaluate the parameters and on the model for GE are discussed. 相似文献
35.
Chun JIN Yin Juan JIA Bin Bin FAN Jing Hong MA Rui Feng LI 《中国化学快报》2006,17(3):419-422
In the last decade, encapsulation of transition metal complexes in zeolites and related materials has been paid much attention, because this type of materials could serve as functional mimic enzymes, possessing both homogeneous-catalysis and heterogeneous… 相似文献
36.
Herein, we demonstrate that the chain-initiating dissociation of cyclohexyl hydroperoxide, CyOOH, is substantially accelerated by H-bond acceptors (e.g. Teflon), which assist O-O bond breaking by stabilising the leaving *OH radical. This is a completely new approach to boost the chain-propagating radical concentration. Indeed, up to now, literature has remained focussed on transition metal catalysis. In addition to this initiation effect, we demonstrate how inert perfluorinated compounds are also able to steer the selectivity at the molecular level, by promoting the conversion of the intermediate cyclohexyl hydroperoxide to the most desired end-product, cyclohexanone. This effect is explained by an enhanced, H-bond-assisted, hydroperoxide propagation. This hitherto overlooked hydroperoxide propagation was recently presented by us as the dominant cyclohexanone and cyclohexanol source. We herein thus confirm our previously reported autoxidation scheme, and illustrate its usefulness as a solid basis for designing new catalytic systems. 相似文献
37.
Spinel systems with the composition of Cu1−xZnxCr2O4 [x = 0 CCr, x = 0.25 CZCr-1, x = 0.5 CZCr-2, x = 0.75 CZCr-3 and x = 1 ZCr] were prepared by homogeneous co-precipitation
method and were characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. Elemental analysis was done by EDX, and surface
area measurements by the BET method. The redox behavior of these catalysts in cyclohexane oxidation at 243 K using TBHP as
oxidant was examined. Cyclohexanone was the major product over all catalysts with some cyclohexanol. 69.2% selectivity to
cyclohexanol and cyclohexanone at 23% conversion of cyclohexane was realized over zinc chromite spinels in 10 h. 相似文献
38.
G. Pratap S. A. Mustafa J. P. Heller 《Journal of polymer science. Part A, Polymer chemistry》1993,31(9):2387-2391
39.
An improved treatment of the lattice model proposed in 1956 is presented for a system of hard rods, with axial ratio x, dispersed in a diluent. Interparticle forces, apart from repulsions on contact, are deliberately ignored within the scope of the present paper. The equilibrium distribution of orientations of the rodlike particles in a phase with nematic order is derived and explicitly taken into account. Thermodynamic properties in the asymptotic limit of high degree of order reduce approximately. to those obtained previously. Calculations carried out for equilibrium between anistropic (nematic) and isotropic phases yield ν′x/νx = 1.4653 for the ratio of volume fractions in the respective phases in the limit x → ∞. The product xνx, expressing the combined covolume of solute species in the isotropic phase at coexistence is 7.89 in the same limit. The calculated critical value of the axial ratio for coexistence of the two phases in the neat liquid is xcrit, = 6.417. Results are compared with those of other theories. Those that rely on the virial expansion are subject to errors implicit in treating the solvent as a continuum. 相似文献
40.