全文获取类型
收费全文 | 485篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 27篇 |
化学工业 | 161篇 |
金属工艺 | 10篇 |
机械仪表 | 7篇 |
建筑科学 | 9篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 27篇 |
石油天然气 | 1篇 |
无线电 | 26篇 |
一般工业技术 | 116篇 |
冶金工业 | 63篇 |
原子能技术 | 15篇 |
自动化技术 | 17篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2019年 | 6篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 34篇 |
2012年 | 24篇 |
2011年 | 29篇 |
2010年 | 21篇 |
2009年 | 21篇 |
2008年 | 13篇 |
2007年 | 17篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 17篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 26篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有496条查询结果,搜索用时 515 毫秒
51.
ABSTRACT Superheated steam drying of sintered spheres of glass beads with different diameters is investigated to reveal the effects of the gravitational force on drying rates. In a previous study, the drying rate curves of small samples with coarse glass beads in which the frictional resistance to flow of water and the effect of the gravitational force are negligible, were predicted by an evaporation zone model.In the present investigation, the drying rate curves of sintered spheres of glass beads with diameters ranging from 1.53×10-2m to 4.99×lO-2m are experimentally and theoretically obtained, and also the capillary pressure curves are measured by use of Haines' apparatus. The drying rate curves of large samples in which the effect of the gravitational force can not be negligible, are compared with those for small samples and the difference among these curves is discussed in terms of the moisture distributions which are estimated from the evaporation zone model with the observed capillary pressure curves. 相似文献
52.
53.
54.
Sintered spheres(made of glass beads) were simply produced with a definite diameter, with a precision of ±0·5 mm in diameter, for a wide range of sintered angles (0-27°). The experimental values of the porosity of the sintered spheres were consistent with the calculated results for the coordination number N ≠ 8. The residual equilibrium saturation, as one of the basic physical properties of sintered glass beads was investigated experimentally and theoretically, resulting in the presence of a distribution in the angle of pendular ring. 相似文献
55.
Akio Katsuki Hiromichi Onikura Takao Sajima Satoshi Machida Kazuhiro Oda 《Precision Engineering》1994,16(4):296-301
A laser-guided BTA tool has been developed to prevent axial hole deviations. Four kinds of experiments were conducted to examine the performance of this tool in detail and to determine its practical application using a duralumin (A2017-T4) workpiece with a prebored 108-mm diameter hole. The first experiment was performed to examine the conditions of the hole deviation in the case of normal deep-hole boring. The second was to examine whether the tool corrects for the stated hole deviation. The third was to examine whether the tool can go straight through to the target without shifting toward a thin wall (t = 0.7 mm) on one side of the workpiece. The fourth was to examine whether the tool can be guided toward the target without affecting a prebored hole, which was inclined to radial direction at 100 μm for a hole length of 100 mm. The experiments were performed with a rotating tool-stationary workpiece system. Rotational speed was 270 rpm and feed ws 0.125 mm/rev. Tool diameter was 110 mm. The results show that the tool can be guided to go straight through toward the target despite the disturbances. 相似文献
56.
Summary Copolymerization of ethylene with -olefins, i.e. propylene, butene-1, 4-methyl-pentene-1(4-MP-1), was carried out by a MgCl2 supported TiCl4 catalyst in combination with Et3Al at a temperature as high as 170 °C at which the polymerization system was homogeneous. This catalytic system showed very a high activity and produced copolymers having a density of 0.91–0.94 g/ml. Of these three kinds of comonomers, propylene showed the highest reactivity and caused most frequently the termination of a polymer growing by chain transfer reaction and produced copolymers having the broadest MWD. 相似文献
57.
The concentration distribution of an antioxidant 2,6-di-tert-butyl-p-cresol (BHT) in the polypropylene (PP) after heating the film containing BHT for a long period of time in succession was studied with use of the rolled film method. The film of 0.003 cm in thickness containing uniformly 710 mg kg?1 of BHT was wound tightly around a glass tube. At the beginning, BHT was distributed uniformly in all layers, and after a given time of the heat treatment at 70–100°C, a remarkable alteration of the concentration distribution of BHT in PP took place. The relations between BHT concentration and the distance from the surface were shown by parabolic curves after heating. The BHT concentration was always kept at almost zero concentration at the surface layer of the rolled film. Assuming that the diffusion obeys Fick's law, the diffusion coefficients at 70, 80, 90, and 100°C were estimated to be 1.05, 4.17, 8.69, and 24.7 × 10?9 cm2 s?1, respectively. The activation energy was calculated as 105 kJ mol?1. 相似文献
58.
Hidenori Yahiro Tatsuya ohuchi Koichi Eguchi Hiromichi Arai 《Journal of Materials Science》1988,23(3):1036-1041
The ionic conduction of oxygen in the ceria-alkaline earth oxide system was investigated as a function of temperature, partial pressure of oxygen and oxide composition, together with its crystal structure, density, and microstructure. Undoped ceria and its solid solution with alkaline earth oxides have a cubic fluorite structure. The ionic conductivity of ceria is greatly enhanced by additions of calcia and strontia, even when they are added in excess of the solubility limit. The conductivities of ceria-calcia and ceria-strontia were much higher than those of calcia-and yttria-stabilized zirconia. Up to the limit of calcia and strontia, the ionic transference number was nearly unity in the temperature range between 600 and 900°C. With an increase in calcia and strontia content, the ionic conductivity was little affected by the presence of a second phase of CaO and SrCeO3. 相似文献
59.
Summary Propylene polymerization was performed with a highly active MgCl supported TiCl4 in conjunction with Et3Al and ethyl benzoate (EB). The obtained polypropylene sample was separated into four fractions by successive extraction with pentane, heptane and trichloroethylene (trichlene). Yield, Mn, Tm and microtacticity of each fraction were determined, and the effects of the concentration of EB on these items of results were investigated. It has been found that EB enhances yield, Mn and stereospecificity of trichlene insoluble (the most stereospecific) fraction, and in contrast, it decreases rapidly yields of other three fractions without changing the character of the polymers. From these findings, the functions of EB to the active centers were discussed. 相似文献
60.
M Kimura T Masuda N Hiwatashi T Toyota H Nagura 《Canadian Metallurgical Quarterly》1994,44(8):624-634
The distribution abnormality of vasoactive intestinal polypeptide-containing nerves (VIP-nerves) and substance P-containing nerves (SP-nerves) was immunohistochemically investigated in the colonic mucosa with inflammatory bowel disease (IBD) in relation to colonic glands and blood vessels in the lamina propria. In active ulcerative colitis (UC), VIP- and SP-nerves decreased in severe inflammatory lesions. VIP-nerves were almost absent particularly around crypt abscesses. Even in resolving and quiescent UC, VIP-nerves still decreased, depending on the decrease of glands and blood vessels. On the other hand, both nerves increased in some hypervascular lesions. In the uninvolved mucosa of UC, they did not change their distribution. In Crohn's disease, the distribution abnormality of both nerves resembled that of UC. These results suggest that the changes in VIP- and SP-nerve distributions in the mucosa with IBD are subsequent to mucosal inflammation and damage. However, these peptides are known to be immunoregulators, and their distribution abnormalities may induce the disorder of immunoregulation in the IBD mucosa and cause the mucosal damage and/or chronicity. 相似文献