全文获取类型
收费全文 | 734篇 |
免费 | 29篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 177篇 |
金属工艺 | 14篇 |
机械仪表 | 17篇 |
建筑科学 | 21篇 |
矿业工程 | 2篇 |
能源动力 | 96篇 |
轻工业 | 51篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 93篇 |
一般工业技术 | 124篇 |
冶金工业 | 46篇 |
原子能技术 | 7篇 |
自动化技术 | 92篇 |
出版年
2024年 | 1篇 |
2023年 | 25篇 |
2022年 | 45篇 |
2021年 | 64篇 |
2020年 | 34篇 |
2019年 | 51篇 |
2018年 | 35篇 |
2017年 | 20篇 |
2016年 | 34篇 |
2015年 | 25篇 |
2014年 | 35篇 |
2013年 | 61篇 |
2012年 | 49篇 |
2011年 | 40篇 |
2010年 | 33篇 |
2009年 | 26篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 17篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有765条查询结果,搜索用时 0 毫秒
71.
Abstract: The stability of microencapsulated fish oil prepared with 2 production processes, spray granulation (SG) and SG followed by film coating (SG-FC) using a fluid bed equipment, was investigated. In the 1st process, 3 types of fish oil used were based on the ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (10/50, 33/22, and 18/12). Each type was emulsified with soluble soybean polysaccharide (SSPS) and maltodextrin to produce 25% oil powders. In the 2nd process, 15% film coating of hydroxypropyl betacyclodextrin (HPBCD) was applied to the granules from the 1st process. The powder stability against oxidation was examined by measurement of peroxide values (PV) and headspace propanal after storage at room temperature and at 3 to 4 °C for 6 wk. Uncoated powder containing the lowest concentration of PUFA (18/12) was found to be stable during storage at room temperature with maximum PV of 3.98 ± 0.001 meq/kg oil. The PV increased sharply for uncoated powder with higher concentration of omega-3 (in 33/22 and 10/50 fish oils) after 3 wk storage. The PVs were in agreement with the concentration of propanal, and these 2 parameters remained constant for most of the uncoated powders stored at low temperature. Unexpectedly, the outcomes showed that the coated powders had lower stability than uncoated powders as indicated by higher initial PVs; more hydroperoxides were detected as well as increasing propanal concentration. The investigation suggests that the film-coating by HPBCD ineffectively protected fish oil as the coating process might have induced further oxidation; however, SG is a good method for producing fish oil powder and to protect it from oxidation because of the “onion skin” structure of granules produced in this process. 相似文献
72.
73.
M. Ashraf A. Naeem Khan Qasair Ali J. Mirza A. Goyal A.M. Anwar 《Construction and Building Materials》2009,23(6):2207-2213
The research was aimed to evaluate the physico-chemical, morphological and thermal analysis of combined pozzolanic activities of minerals additives. Fly ash and ground granulated blast furnace slag were added, separately and collectively, as mineral replacement in ordinary Portland cement. Tests carried out on specimens cured at different ages were: compressive strength, ultrasonic pulse velocity, X-ray diffraction (XRD) analysis, scanning electron microscopic (SEM) studies, differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA), etc. The results indicated that the compressive strength and ultrasonic pulse velocity development rate of concrete specimens were significantly influenced by the addition of mineral additives. SEM data showed that the fly ash particles were more embedded and surrounded by slag. XRD analysis and DTA/TGA investigation have revealed different reaction kinetics of paste. The peak intensity of calcium hydroxide was significantly retarded by the addition of fly ash and slag, especially in combination, attributed to the dilution effect and calcium hydroxide consumption by pozzolanic reaction. 相似文献
74.
Background
Obesity in Canadian children increased three-fold in twenty years. Children living in low-income neighborhoods exercise less and are more overweight than those living in more affluent neighborhoods after accounting for family socio-economic status. Strategies to prevent obesity in children have focused on personal habits, ignoring neighborhood characteristics. It is essential to evaluate diet and physical activity patterns in relation to socio-economic conditions to understand the determinants of obesity. The objective of this pilot study was to compare diet, physical activity, and the built environment in two Hamilton area elementary schools serving socio-economically different communities. 相似文献75.
SM Laidlaw MA Anwar W Thomas P Green K Shaw MA Skinner 《Canadian Metallurgical Quarterly》1998,72(8):6742-6751
The genome of fowlpox virus (FWPV), type species of the Avipoxviridae, is considerably rearranged compared with that of vaccinia virus (the prototypic poxvirus and type species of the Orthopoxviridae) and is 30% larger. It is likely that the genome of FWPV contains genes in addition to those found in vaccinia virus, probably involved with its replication and survival in the chicken. A 7,470-bp segment of the FWPV genome has five open reading frames (ORFs), two of which encode ankyrin repeat proteins, many examples of which have been found in poxviruses. The remaining ORFs encode homologs of cellular genes not reported in any other virus. ORF-2 encodes a homolog of the yeast Sec17p and mammalian SNAP proteins, crucial to vesicular transport in the exocytic pathway. ORF-3 encodes a homolog of an orphan human protein, R31240_2, encoded on 19p13.2. ORF-3 is also homologous to three proteins (YLS2, YMV6, and C07B5.5) from the free-living nematode Caenorhabditis elegans and to a 43-kDa antigen from the parasitic nematode Trichinella spiralis. ORF-5 encodes a homolog of the mammalian plasma cell antigen PC-1, a type II glycoprotein with exophosphodiesterase activity. The ORFs are present in the virulent precursor, HP1, of the sequenced attenuated virus (FP9) and are conserved in other strains of FWPV. They were shown, by deletion mutagenesis, to be nonessential to virus replication in tissue culture. RNA encoding the viral homolog of PC-1 is expressed strongly early and late in infection, but RNAs encoding the homologs of SNAP and R31240_2 are expressed weakly and late. 相似文献
76.
77.
A study of the effects of changes in composition, film thickness, substrate deposition temperature and annealing on the optical properties of MoO3-In2O3 is presented. The results are found to be compatible with the reduction in the value of optical energy gap of these materials as the molar fraction of In2O3 in the MoO3 thin film increases. This decrease of optical gap may be attributed to the incorporation of In(III) ions in an MoO3 lattice. The decrease in optical band gap with increasing thickness may be interpreted in terms of the incorporation of oxygen vacancies which are also believed to be the source of conduction electrons in the MoO3-In2O3 complex. The decrease of band gap with increasing substrate temperature may be attributed to the enhanced ordering of the samples and the decrease of band gap with annealing may be attributed to a reduction in the concentration of lattice imperfections. 相似文献
78.
79.
Mahesh Kumar G. Janardhana Reddy G. Ravi Kiran M. A. Mohammed Aslam O. Anwar Beg 《亚洲传热研究》2019,48(3):1067-1092
Entropy generation is an important aspect of modern thermal polymer processing optimization. Many polymers exhibit strongly non‐Newtonian effects and dissipation effects in thermal processing. Motivated by these aspects in this study, a numerical analysis of the entropy generation with viscous dissipation effect in an unsteady flow of viscoelastic fluid from a vertical cylinder is presented. The Reiner‐Rivlin physical model of grade 2 (second‐grade fluid) is used, which can envisage normal stress variations in polymeric flow‐fields. Viscosity variation is included. The obtained governing equations are resolved using implicit finite difference method of Crank‐Nicolson type with well imposed initial and boundary conditions. Key control parameters are the second‐grade viscoelastic fluid parameter (), viscosity variation parameter (), and viscous dissipation parameter (). Also, group parameter (), Grashof number (Gr), and Prandtl number (Pr) are examined. Numerical solutions are presented for steady‐state flow variables, temperature, time histories of friction, wall heat transfer rate, entropy, and Bejan curves for distinct values of control parameters. The results specify that entropy generation decreases with augmenting values of , , and Gr. The converse trend is noticed with increasing Pr and . Furthermore, the computations reveal that entropy and Bejan lines only occur close to the hot cylinder wall. 相似文献