首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1284篇
  免费   2篇
  国内免费   1篇
电工技术   2篇
化学工业   44篇
金属工艺   44篇
机械仪表   38篇
能源动力   3篇
轻工业   4篇
水利工程   3篇
石油天然气   15篇
无线电   16篇
一般工业技术   154篇
冶金工业   897篇
原子能技术   41篇
自动化技术   26篇
  2022年   5篇
  2021年   7篇
  2019年   8篇
  2018年   23篇
  2017年   18篇
  2016年   16篇
  2015年   6篇
  2014年   5篇
  2013年   24篇
  2012年   8篇
  2011年   15篇
  2010年   22篇
  2009年   16篇
  2008年   17篇
  2007年   9篇
  2006年   8篇
  2005年   9篇
  2004年   7篇
  2003年   5篇
  2002年   5篇
  2001年   4篇
  2000年   6篇
  1999年   27篇
  1998年   241篇
  1997年   150篇
  1996年   112篇
  1995年   56篇
  1994年   41篇
  1993年   47篇
  1992年   13篇
  1991年   17篇
  1990年   16篇
  1989年   18篇
  1988年   19篇
  1987年   10篇
  1986年   16篇
  1985年   24篇
  1984年   5篇
  1983年   7篇
  1982年   13篇
  1981年   12篇
  1980年   9篇
  1979年   4篇
  1978年   7篇
  1977年   29篇
  1976年   95篇
  1975年   4篇
  1972年   5篇
  1971年   6篇
  1970年   9篇
排序方式: 共有1287条查询结果,搜索用时 15 毫秒
51.
The processes of heating a body in a high-enthalpy spatial flow with allowance for body rotation around its longitudinal axis and ablation of the thermal protection material are studied by means of mathematical simulation. The obtained solution of the problem in conjugate formulation allowed us to take into account the effect of nonisothermic characteristics of the shell on the heat and mass transfer in the boundary layer.  相似文献   
52.
The formation and motion of gas bubbles in the melt substantially affect the heat exchange and kinetics of chemical transformations when performing the fire refining of copper in the ladle furnace. The variation in the bubble velocity, as well as of the volume and surface of the moving gas bubble over the melt height, is considered in the presented mathematical model.  相似文献   
53.
In the AgCl microcrystals with adsorbed methylene blue dye molecules, sensitized anti-Stokes luminescence centers formed as a result of a photostimulated low-temperature (77 K) process are observed. The emission is recorded on excitation of the samples by radiation with the flux density 1014?1015 photon cm?2 s?1 in the spectral range 620–750 nm corresponding to optical absorption in the adsorbed dye molecules and adsorbed Ag1, Ag2, and Ag3 clusters. It is shown that the anti-Stokes luminescence centers formed by photo-stimulation present (adsorbed dye molecule)—(silver subnanocluster) hybrid nanostructures, in which the bonding between the components is weak but sufficient to provide the possibility for two-photon interband transitions that occur due to transfer of the electron’s excitation energy from the dye molecule to the silver cluster with subsequent photoionization of the cluster.  相似文献   
54.
55.
The special features of electron beam welding of pressed strips of the V-1963-strength aluminium alloy of the Al–Zn–Mg–Cu system with a thickness of 40 mm are investigated. The results of tests of the welded joints in static tensile loading, bending, and impact toughness of the weld metal are presented. It is shown that the strength of the welded joints equals 0.7–0.8 of the strength of the parent material. The results of investigations of the macro- and microstructure of the welded joints are generalized and it is shown that the welded joints are characterized by the formation of an equiaxed fine-grained structure with the grain size of 5–10 μm.  相似文献   
56.
An algorithm for filtering acoustic-emission signals and a technique for measuring the velocity of sound during searches for leaks in pipelines of heat networks are considered. The results of experimental studies are presented.  相似文献   
57.
58.
Refractory hypotension with end-organ hypoperfusion is an ominous feature of inflammatory shock. In the past fifteen years, nitric oxide (a diffusible, short-lived product of arginine metabolism) has been found to be an important regulatory molecule in several areas of metabolism, including vascular tone control. Vascular endothelial cells constitutively produce low levels of nitric oxide that regulate blood pressure by mediating adjacent smooth-muscle relaxation. In an inflammatory shock state, cytokines, like interleukin-1 and tumor necrosis factor-alpha, induce a separate, high-output form of the enzyme that synthesizes nitric oxide in both endothelial and smooth-muscle cells. The ensuing high rates of nitric oxide formation result in extensive smooth-muscle relaxation, pressor refractory vasodilation, and--ultimately--shock. The concept of the pathogenesis of inflammatory shock explains many limitations of current therapies and may foster the development of new interventions to mitigate the effects of nitric oxide overproduction in this syndrome.  相似文献   
59.
BACKGROUND: The purpose was to study activation markers of the eosinophil granulocytes in seasonal allergic rhinitis, and the impact of topical steroid therapy thereupon. METHODS: Sixty-three rhinitis patients with monoallergy to grass were examined before and at peak pollen season. Blood eosinophil count, eosinophil cationic protein (ECP), and eosinophil peroxidase (EPO) in serum and nasal lavage fluid were measured. During the season, patients were randomized to treatment with intranasal fluticasone propionate 0.1 mg o.d. (n=26), 0.2 mg o.d. (n=25), or placebo (n=12). Six healthy persons served as controls. RESULTS: During the season, all parameters, except nasal lavage ECP, increased in the placebo group (P<0.001-P<0.05). Significant differences were seen between the steroid groups and the placebo group for all parameters (P<0.001-P<0.05). Higher eosinophil count (P<0.05), serum EPO (P<0.02), and nasal lavage EPO (P<0.05) were found in patients before season than in controls. The following winter, 44 patients returned for repeated measurement. Lower levels of nasal lavage EPO were observed for patients than levels at the beginning of the season (P<0.0001). CONCLUSIONS: Intranasal fluticasone propionate reduced inflammation of the nasal mucosa, demonstrated locally by nasal lavage ECP and EPO, and systemically by blood eosinophils, serum ECP, and serum EPO. EPO seemed more sensitive than ECP as indicator of allergic inflammation. EPO demonstrated some perennial eosinophil activity in hay fever patients, increasing locally during spring.  相似文献   
60.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号