全文获取类型
收费全文 | 710篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
化学 | 466篇 |
晶体学 | 6篇 |
力学 | 10篇 |
数学 | 65篇 |
物理学 | 200篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 22篇 |
2014年 | 22篇 |
2013年 | 35篇 |
2012年 | 36篇 |
2011年 | 42篇 |
2010年 | 28篇 |
2009年 | 43篇 |
2008年 | 53篇 |
2007年 | 42篇 |
2006年 | 49篇 |
2005年 | 38篇 |
2004年 | 29篇 |
2003年 | 27篇 |
2002年 | 20篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有747条查询结果,搜索用时 0 毫秒
131.
While most other glasses exhibit non-exponential structural relaxation characteristics even when the change of fictive temperature is small, a high purity silica glass exhibited exponential structural relaxation. This was demonstrated by showing that the non-exponential exponent or β value of the KWW function of the high purity silica glass approaches unity when the change of the fictive temperature approaches zero both from higher and lower temperature sides of the heat-treatment temperature. The non-exponentiality of the structural relaxation of this glass when fictive temperature change is finite is due to the change of relaxation time during the structural relaxation. 相似文献
132.
D.C. Suministrado M. Koike T. Konaka S. Yuzawa I. Kuroishi 《Journal of Terramechanics》1990,27(4):307-320
Using mathematical models, approximate trajectories of soil furrow subslices were determined and the forces occurring on the moldboard surface were calculated. The various components of the normal force along the trajectory line of the middle section of the furrow slice were analysed in relation to the velocity of plowing operation and the curvature of the path. The soil reaction forces encountered by the share portion of the plow were also determined by a model which used the method of trial wedges to determine the angle of the failure surface with the horizontal. The sum of the calculated forces was compared with that obtained by actual plowing experiments performed in the laboratory. 相似文献
133.
134.
We have developed efficient electrocatalysts for methanol oxidation using new synthetic method facilitating deposition of Pt–Ru very thin nanoplatelets on carbon nanoparticles The method involves oxidation of carbon support, adsorption of Pb2+, its reduction and galvanic displacement of Pb0 by Pt and/or Ru. The Pt mass activity of this catalyst is about 10 times higher than that of the commercial Pt–Ru/C. The catalyst with the 1:1 Pt/Ru ratio displayed the highest methanol oxidation activity per surface Pt atom. Our results demonstrate the new synthetic method that yields the catalyst with potential for solving the problem of high Pt loading in direct methanol fuel cell anodes. 相似文献
135.
136.
137.
In order to create a mathematical model of a soil-cutting blade, it is necessary to understand thoroughly the behavior of a soil slice and its interaction with the blade surface. The triaxial force transducer was developed to serve as one of the various tools to verify the proposed mathematical model. The prototype model transducer was fabricated, calibrated and tested with a soil slice on a flat cutting blade. The calibration results have indicated high sensitivity and the capability of simultaneous measurement in three directions. As a technological refinement, the detecting part of this triaxial force transducer was tapered to solve the problem of soil clogging in the opening clearance. Furthermore, the effects of the clearance configurations between the bore on the soil-cutting blade and the detecting part which is embedded in this bore were investigated to determine the most desirable configuration. The comparative results indicated that by tapering both the detecting part and the bore, the tangential stress measurement gained the highest value, and provided the most satisfactory condition for three-dimensional stress management. 相似文献
138.
Looking-glass synergistic pharmacological chaperones: DGJ and L-DGJ from the enantiomers of tagatose
Jenkinson SF Fleet GW Nash RJ Koike Y Adachi I Yoshihara A Morimoto K Izumori K Kato A 《Organic letters》2011,13(15):4064-4067
The enantiomers of tagatose are converted to L-DGJ [a noncompetitive inhibitor of human lysosome α-galactosidase A (α-Gal A), K(i) 38.5 μM] and DGJ [a competitive inhibitor of α-Gal A, K(i) 15.1 nM] in 66% yield. L-DGJ and DGJ provide the first examples of pharmacological chaperones that (a) are enantiomeric iminosugars and (b) have synergistic activity with implications for the treatment of lysosomal storage disorders and other protein deficiencies. 相似文献
139.
Morita K Sankaran NB Huang W Seino T Sato Y Nishizawa S Teramae N 《Chemical communications (Cambridge, England)》2006,(22):2376-2378
An abasic site-containing DNA combined with lumiflavin allows amperometric determination of single nucleotide polymorphism through hydrogen bond-mediated nucleobase recognition in water by using abasic sites as a molecular recognition field. 相似文献
140.
H. Ohkita K. Ishibashi D. Tsurumoto A. Tagaya Y. Koike 《Applied Physics A: Materials Science & Processing》2005,81(3):617-620
We report on a method to compensate the photoelastic birefringence of a polymer. In this method, a rod-like molecule that has a polarizability anisotropy was chosen and doped in a polymer. We demonstrated this method by compensating the negative photoelastic birefringence of poly(methylmethacrylate) at a wavelength of 633 nm. Homogeneous doping with 2.2 wt. % of trans-stilbene almost eliminated the photoelastic birefringence of the polymer. The photoelastic coefficient of the synthesized zero-photoelastic birefringence polymer was 0.057×10-12 Pa-1. We found that the photoelastic birefringence of poly(methylmethacrylate) was compensated by the motion of trans-stilbene in the polymer by the analysis of the infrared absorption spectrum. PACS 42.70.-a; 42.70.Jk; 78.30.Jw 相似文献