全文获取类型
收费全文 | 387篇 |
免费 | 18篇 |
国内免费 | 5篇 |
专业分类
化学 | 301篇 |
晶体学 | 3篇 |
力学 | 17篇 |
数学 | 28篇 |
物理学 | 61篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 22篇 |
2012年 | 22篇 |
2011年 | 16篇 |
2010年 | 13篇 |
2009年 | 16篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 30篇 |
2005年 | 38篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有410条查询结果,搜索用时 15 毫秒
1.
2.
K. Uno M. Makita S. Ooi Y. Iwakura 《Journal of polymer science. Part A, Polymer chemistry》1968,6(2):257-267
Copolymerization of methacrylic esters derived from glycidyl methacrylate and nucleophiles with styrene was carried out. The monomer reactivity ratios of these methacrylic esters were varied with the alkoxy groups of the esters and the solvent used. 相似文献
3.
A unique asymmetric skeletal rearrangement of symmetrically alpha,alpha-disubstituted alpha-amino aldehydes has been accomplished for the first time using a chiral organoaluminum Lewis acid 1. For instance, treatment of (S)-2,2'-bis(trifluoromethanesulfonylamino)-1,1'-binaphthyl with Me3Al (1.0 equiv) in toluene at room temperature for 15 min and at 110 degrees C for an additional 15 min produced (S)-1, and a subsequent reaction with alpha -amino aldehyde 2a (R = CH2Ph) at -78 degrees C for 4 h and at -40 degrees C for 12 h resulted in the smooth rearrangement to the zwitterionic iminium intermediate A, which furnished the alpha-hydroxy ketone 3a (R = CH2Ph) in 93% isolated yield with 95% ee (S) after acidic hydrolysis. This result, together with other representative examples, clearly demonstrates the effectiveness of the present method for the hitherto difficult asymmetric synthesis of acyloins. Furthermore, we found that the treatment of the in situ generated A with DIBAH afforded the corresponding anti amino alcohol exclusively without loss of enantiomeric excess. Our approach casts light on the previously unexplored yet potential utility of alpha-amino aldehydes as synthetic building blocks and also provides a new entry to optically active alpha-hydroxy ketones and 1,2-amino alcohols. 相似文献
4.
Ooi Y Hobara D Yamamoto M Kakiuchi T 《Langmuir : the ACS journal of surfaces and colloids》2005,21(24):11185-11189
In formation of binary self-assembled monolayers (SAMs) composed of 2-aminoethanethiol (AET) and 2-mercaptoethane sulfonic acid (MES) by adsorption from an ethanol solution on Au(111), the adsorption shows nearly ideal nonideality in that the surface ratio of MES to AET in the SAM is unity and does not depend on the mixing ratio of MES to AET in the bathing ethanol solution used for preparing SAMs, chi(soln)MES, over the wide range of chi(soln)MES between 0.01 and 0.95. X-ray photoelectron spectroscopy confirms that at least 80% of AET molecules adsorbed are protonated in this range of chi(soln)MES, indicating that the electrostatic interaction between positively charged AET and negatively charged MES is responsible to the observed nonideality. Correspondingly, there appears only one cathodic peak in a linear-sweep voltammogram of the reductive desorption of the SAM, having a narrow full width at half-maximum of about 20 mV. This suggests the presence of strong lateral attractive interaction between the adsorbed thiolates. 相似文献
5.
The intercalation of 4-phenylazoaniline (PAA) in supercritical carbon dioxide (SC-CO(2)) into montmorillonite (TMA-Mnt) pillared with tetramethylammonium ions at 313 K and 15 MPa was investigated. The adsorption rate and equilibrium PAA uptake were compared with those in n-hexane, CCl(4) and benzene solutions at 313 K. The XRD and N(2) adsorption/desorption analyses showed that TMA-Mnt after adsorption of PAA in SC-CO(2) had the same pore structure as after adsorption of PAA in normal solvents. SC-CO(2) was found to be a good medium for PAA adsorption owing to its having a relatively high adsorption rate and the highest adsorptivity at the same PAA concentration. The properties of PAA adsorption on TMA-Mnt could be well elucidated by the difference in solubility parameters between liquid and solid phases. 相似文献
6.
Czechoslovak Mathematical Journal - We characterize the Choquet integrals associated to Bessel capacities in terms of the preduals of the Sobolev multiplier spaces. We make use of the boundedness... 相似文献
7.
In this paper, we give a construction of partial difference sets in p
2 x p
2 x ... x p
2using some finite local rings.Dedicated to Hanfried Lenz on the occasion of his 80th birthdayThe work of this paper was done when the authors visited the University of Hong Kong. 相似文献
8.
This paper presents a mathematical model to describe a two-fluid electroosmotic pumping technique, in which an electrically non-conducting fluid is delivered by the interfacial viscous force of a conducting fluid; the latter is driven by electroosmosis. The electrical potential in the conducting fluid and the analytical solution of the steady two-fluid electroosmotic stratified flow in a rectangular microchannel was presented by assuming a planar interface between the two immiscible fluids. The effects of viscosity ratio, hold-up, concentration, and interfacial zeta potential are analyzed to show the potential feasibility of this technique. 相似文献
9.
Ramesh Chitrakar Hirofumi KanohYoshitaka Miyai Kenta Ooi 《Journal of solid state chemistry》2002,163(1):1-4
Microwave irradiation of a suspension of γ-MnOOH in a 4 mol dm−3 LiOH solution brought about a rapid formation of semicrystalline orthorhombic LiMnO2 (o-LiMnO2) within 30 min at 120°C. Cubic Li1.6Mn1.6O4 was obtained by heating o-LiMnO2 at 400°C; lithium could be topotactically extracted from Li1.6Mn1.6O4 with acid to form cubic H1.6Mn1.6O4. 相似文献
10.