全文获取类型
收费全文 | 355篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
化学 | 154篇 |
晶体学 | 3篇 |
力学 | 12篇 |
数学 | 128篇 |
物理学 | 60篇 |
出版年
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 23篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 3篇 |
2007年 | 11篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 8篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1970年 | 3篇 |
1966年 | 5篇 |
1965年 | 3篇 |
1963年 | 5篇 |
1956年 | 3篇 |
1955年 | 3篇 |
1954年 | 2篇 |
1942年 | 8篇 |
1941年 | 5篇 |
1940年 | 4篇 |
1939年 | 2篇 |
排序方式: 共有357条查询结果,搜索用时 15 毫秒
351.
Let K be an algebraic number field. We discuss the problem of counting the number of integral ideals below a given norm and obtain effective error estimates. The approach is elementary and follows a classical line of argument of Dedekind and Weber. The novelty here is that explicit error estimates can be obtained by fine tuning this classical argument without too much difficulty. The error estimate is sufficiently strong to give the analytic continuation of the Dedekind zeta function to the left of the line R(s)=1 as well as explicit bounds for the residue of the zeta function at s=1. 相似文献
352.
M.S.N. Murty K.V. RameshG. Prabhakar P. Venkateswarlu 《Experimental Thermal and Fluid Science》2011,35(2):338-346
Three-phase fluidized beds are found to have wide applications in process industries. The present investigation essentially comprises of the studies on gas holdup, liquid holdup and bed porosity in three-phase fluidized beds with coaxially placed disc promoter. Holdup data were obtained from bed expansion and pressure drop measurements. Analysis of the data was done to elucidate the effects of dynamic and geometric parameters on gas holdup, liquid holdup and bed porosity. Data were correlated and useful equations were obtained from empirical modeling. 相似文献
353.
I.N. PrakashB. Babu Ch. Venkata ReddyP. Narayana Murty Y.P. ReddyP. Sambasiva Rao R.V.S.S.N. Ravikumar 《Physica B: Condensed Matter》2011,406(17):3295-3298
EPR and optical absorption studies on Fe3+ and Mn2+ doped strontium tetraborate (SrB4O7) glasses are carried out at room temperature. The EPR spectrum of the Fe3+ doped glass consists of signals with g-values 9.04, 4.22 and 2.04, whereas the EPR spectrum of Mn2+ doped glass exhibits a characteristic hyperfine sextet around g=2.0. The spectroscopic analyses of the obtained results confirmed distorted octahedral site symmetry for the Fe3+ and Mn2+ impurity ions. Crystal field and Racah parameters evaluated from optical absorption spectra are: Dq=790, B=700 and C=3000 cm−1 for Fe3+doped glass and Dq=880, B=700 and C=2975 cm−1 for Mn2+ doped glass. 相似文献
354.
Helane?MS?Costa Augusto?CV?Freitas Júnior Ian?PG?Amaral Izaura?Y?Hirata Patrícia?MG?Paiva Luiz?B?CarvalhoJr Vitor?Oliveira Ranilson?S?BezerraEmail author 《Chemistry Central journal》2013,7(1):166
Background
Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.Results
A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-α-benzoyl-DL-arginine-p-nitroanilide (BApNA) as substrate. In addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50°C, respectively. After incubation at 50°C for 30 min the enzyme lost only 20% of its activity. K m , kcat, and k cat /K m values using BApNA as substrate were 0.689 mM, 6.9 s-1, and 10 s-1 mM-1, respectively. High inhibition of trypsin activity was observed after incubation with Cd2+, Al3+, Zn2+, Cu2+, Pb2+, and Hg2+ at 1 mM, revealing high sensitivity of the enzyme to metal ions.Conclusions
Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.355.
356.
Das B Majhi A Banerjee J Chowdhury N Holla H Harakishore K Murty US 《Chemical & pharmaceutical bulletin》2006,54(3):403-405
2-Benzoxepines have efficiently been synthesized from Morita-Baylis-Hillman adducts, alkyl 3-aryl-3-hydroxy-2-methylenepropanoates by treatment with HCHO catalyzed by silica supported perchloric acid (HClO4.SiO2) or Amberlyst-15 in CH2Cl2 under reflux for a short period of time (1.5-2.5 h). The catalyst can be recovered and recycled. The antibacterial properties of the new 2-benzoxepines were studied but no activity was found. 相似文献