全文获取类型
收费全文 | 107篇 |
免费 | 0篇 |
国内免费 | 9篇 |
专业分类
化学 | 18篇 |
力学 | 5篇 |
数学 | 15篇 |
物理学 | 78篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 8篇 |
2014年 | 34篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 10篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1963年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有116条查询结果,搜索用时 15 毫秒
21.
The effect of laser beam size in a zig-zag collimator on transverse cooling of a krypton atomic beam
The effect of size of a cooling laser beam in a zig-zag atomic beam collimator on transverse cooling of a krypton atomic beam is investigated. The simulation results show that discreteness in the interaction between the cooling laser beam and atomic beam, arising due to finite size and incidence angle of the cooling laser beam, significantly reduces the value of transverse velocity capture range of the collimator. The experimental observations show the trend similar to that obtained from simulations. Our study can be particularly useful where a small zig-zag collimator is required. 相似文献
22.
The feasibility study for searching neutrinoless double beta decay in 124Sn using cryogenic bolometer has been initiated. For this purpose, a custom-built cryogen-free dilution refrigerator, having a large cooling power of 1.4 mW at 120 mK, has been installed at TIFR, India. This paper describes the design, installation and performance of a cryogen-free dilution refrigerator (CFDR-1200). The performance of CFDR-1200 has been analysed using Takano’s model developed for conventional (wet) dilution refrigerators. 相似文献
23.
24.
25.
A simple and fast three-component diastereoselective synthesis of biologically important spiro scaffold 4 wascarried out in reasonable purity starting from readily available 1H-indole-2,3-dione 1,ethyl cyanoacetate 2 and4-hydroxycoumarin 3 under microwave in high yield(88%-92%)and short time. 相似文献
26.
27.
28.
The pyrolysis of eucalyptus wood was carried out in a batch reactor to optimize the yield of bio-oil.Effect of various parameters like feed(particle) size,temperature,presence of catalyst and heating rate on the yield of bio-oil was investigated.The optimum conditions for high yield of bio-oil are for the particle size 2 mm~5 mm(average l/d=12.84/2.03 mm) at 450 ℃ in high heating rate.The reaction kinetics and the quality of bio-oil produced are independent of the presence of different catalysts like mordenite,kaoline clay,fly ash and silica alumina.The physical properties like odour,colour,PH,viscosity,heating value were determined.The FT-IR analysis of bio-oil indicates the presence of different functional groups such as monomeric alcohol,phenol,ketones,aldehydes,carboxylic acid,amines,and nitro compounds.The composition of the bio-oil at different conditions was analyzed using GC-MS and found that the components are temperature dependent but independent of catalysts used. 相似文献
29.
The problem of the creeping flow through a spherical droplet with a nonhomogenous porous layer in a spherical container has been studied analytically. Darcy’s model for the flow inside the porous annular region and the Stokes equation for the flow inside the spherical cavity and container are used to analyze the flow. The drag force is exerted on the porous spherical particles enclosing a cavity, and the hydrodynamic permeability of the spherical droplet with a non-homogeneous porous layer is ca... 相似文献
30.
NANDINI CHATTERJEE SINGH 《Pramana》2011,77(5):811-816
Sounds in the natural environment form an important class of biologically relevant non-stationary signals. We propose a dynamic
spectral measure to characterize the spectral dynamics of such non-stationary sound signals and classify them based on rate
of change of spectral dynamics. We categorize sounds with slowly varying spectral dynamics as simple and those with rapidly
changing spectral dynamics as complex. We propose rate of spectral dynamics as a possible scheme to categorize sounds in the
environment. 相似文献