全文获取类型
收费全文 | 177篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 133篇 |
力学 | 5篇 |
数学 | 8篇 |
物理学 | 39篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 7篇 |
2009年 | 1篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有185条查询结果,搜索用时 265 毫秒
101.
Eudesmane type α-methylene-γ-lactones, reynosin (1), santamarine (2), epoxysantamarine (3) and 1β-hydroxyarbusculin A (4) have been synthesized from α-santonin. 相似文献
102.
103.
104.
105.
This paper proposes a practical measurement system for bidirectional reflectance distribution functions (BRDFs) of a three-dimensional
(3D) object with a linear light source. Using the linear light source, the proposed system can reduce the number of image
acquisitions which are necessary for an estimation of the spatially-varying BRDFs of the object. Furthermore, the size of
the proposed system is much smaller than a conventional system which uses a parallel light. In this proposed system, the light
field of the linear light source is previously measured to determine direction and radiance of incident rays to each point
of the object, because the direction and radiance are not constant at each point. Using the proposed system, the BRDF of a
point of flat objects was experimentally measured, and results showed validation of the estimation accuracy of the proposed
system. Measurement efficiency of the proposed system was also evaluated by comparing reflectance model parameters estimated
by the conventional and proposed systems. For the estimation, the reflectance function of a 3D object was measured by both
systems. The estimation accuracy of the proposed method was also evaluated by comparing among a real image and rendered 3D
objects of the conventional and proposed methods. 相似文献
106.
S. Tsushima S. Hirai K. Kitamura M. Yamashita S. Takase 《Applied magnetic resonance》2007,32(1-2):233-241
Magnetic resonance imaging (MRI) is applied to clarify a dominating factor on variation of fuel cell performance with two
types of polymer electrolyte membranes, a hydrocarbon membrane and a perfluorinated membrane. MRI results revealed that the
hydrocarbon membrane showed a water content higher than that of the perfluorinated membrane, responsible for a better fuel
cell performance due to decrease of resistance loss of the fuel cell.
Authors' address: Shohji Tsushima, Research Center for Carbon Recycling and Energy, Tokyo Institute of Technology, 2-12-1,
Ohokayama, Meguro-ku, Tokyo 152-8552, Japan 相似文献
107.
108.
The title quinarenone 2 has been prepared and proved that the three-membered ring possesses a larger diatropicity than diphenylcyclopropenone and the seven-membered ring exists in a cycloheptatriene (not norcaradiene) tautomer having a contribution of a homobenzene structure. The rotational barrier about the intercyclic bond of 2 is 13.3 Kcal/mol. 相似文献
109.
We experimentally investigate the performance of a commercial tapered amplifier diode operating in a pulsed-current mode with a peak current that is significantly higher than the specified maximum continuous current. For a tapered amplifier rated at 500 mW of continuous power, we demonstrate 2.6 W of peak optical output power with 15 mW of injection light for 200 micros, 7 A current pulses. Different failure mechanisms for the tapered amplifier, including thermal and optical damage, are identified under these conditions. 相似文献
110.
Ruthenium(II) complexes bearing a redox-active tridentate ligand 4′-(2,5-dimethoxyphenyl)-2,2′:6′,2′′-terpyridine (tpyOMe), analogous to terpyridine, and 2,2′-bipyridine (bpy) were synthesized by the sequential replacement of Cl by CH3CN and CO on the complex. The new ruthenium complexes were characterized by various methods including IR and NMR. The molecular structures of [Ru(tpyOMe)(bpy)(CH3CN)]2+ and two kinds of [Ru(tpyOMe)(bpy)(CO)]2+ were determined by X-ray crystallography. The incorporation of monodentate ligands (Cl, CH3CN and CO) regulated the energy levels of the MLCT transitions and the metal-centered redox potentials of the complexes. The kinetic data observed in this study indicates that the ligand replacement reaction of [Ru(tpyOMe)(bpy)Cl]+ to [Ru(tpyOMe)(bpy)(CH3CN)]2+ proceeds by a solvent-assisted dissociation process. 相似文献