全文获取类型
收费全文 | 744篇 |
免费 | 26篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 130篇 |
金属工艺 | 3篇 |
机械仪表 | 24篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 10篇 |
轻工业 | 49篇 |
水利工程 | 16篇 |
石油天然气 | 3篇 |
无线电 | 49篇 |
一般工业技术 | 106篇 |
冶金工业 | 289篇 |
自动化技术 | 53篇 |
出版年
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 19篇 |
2011年 | 26篇 |
2010年 | 27篇 |
2009年 | 10篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 20篇 |
2005年 | 27篇 |
2004年 | 12篇 |
2003年 | 19篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 19篇 |
1998年 | 83篇 |
1997年 | 50篇 |
1996年 | 39篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 8篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1981年 | 4篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有770条查询结果,搜索用时 15 毫秒
41.
The PLUGE method is described, and its advantages are given. Five sets of reference conditions for setting up picture monitors are presented. Further, it is shown that the required PLUGE black level is dependent upon the value of base luminance. 相似文献
42.
"This study was designed to test the hypothesis that Rokeach's Dogmatism Scale [1960], structurally identical to the F scale, is similarily vulnerable to acquiescent response bias." Administration of acquiescent response scales, the F Scale, and the Dogmatism scale to a population of adult neurotics revealed a high intercorrelation, which supports the hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
44.
45.
The pressure dependencies of the conductivities of nickel and cobalt monoxides have been investigated in the range 10–2 to 7.5 × 102 atmospheres at temperatures in the region of 1000° C. Conductivity saturation occurs in CoO due to the formation of Co3O4, and the experimental data correlates well with a model for the separation of the higher phase. NiO exhibits no saturation effect in the pressure range investigated and the p1/5 dependence of the conductivity at 950° C with this oxide above 0.1 atm is interpreted in terms of the formation of singly ionised vacancies. 相似文献
46.
Acetone powders prepared fromVernonia anthelmintica seed catalyzed the release of 6.4 to 9.6 μ-moles of free fatty acids per milligram of protein when blended with olive oil
and phosphate buffer and shaken for 20 min at 43 C. A 20 fold purification was achieved by differential centrifugation of
an ammonium hydroxide extract of the acetone powder. Results from Sephadex G-200 chromatography and polyacrylamide gel electrophoresis
suggested that the lipase activity was associated with a molecule of molecular weight greater than 200,000. Free fatty acids,
1,2- and 1,3-diglycerides, monoglycerides and glycerol were found in the digestion products. With most substrates the 1,2-to
1,3-diglyceride ratio was approximately 2∶1 and monoglycerides tended to accumulate. Analysis of the digestion products from
synthetic triglycerides of known structure indicated that both primary and secondary ester positions of the triglyceride molecule
were hydrolyzed and that considerable isomerization of 1,2-diglyceride to 1,3-diglyceride occurred. The monoglyceride was
consistently lower than the 1,2-diglyceride and in the majority of cases also lower than the 1,3-diglyceride in the fatty
acid originally present in the 2 position of the triglyceride. No fatty acid preference was observed.
Scientific contribution No. 316.
Presented in part at the AOCS Meeting, Philadelphia, October 1966. 相似文献
47.
The oscillatory motion and stability of a liquid jet are examined in the context of a theory which accounts for local variations of interfacial tension induced by expansion and contraction of an interface containing adsorbed molecules. The presence of a soluble surfactant alters the oscillation frequency as well as growth and decay rates via damping in a boundary layer. It is found that the frequency alteration is a substantial effect when considered in the context of measurements made with oscillating jets, i.e. the dynamic surface tension. When viscous effects are large the presence of surfactant may introduce oscillatory character in place of the aperiodic temporal behavior of pure liquids. 相似文献
48.
49.
50.
A systematic review of the neurologic literature identified 433 cases of pathologically proven multiple system atrophy over a 100-year period. Earlier case reports included patients younger in age with more frequent cerebellar involvement. Mean age of onset was 54.2 years (range 31 to 78) and survival was 6.2 years (range 0.5 to 24). Survival analysis showed a secular trend from a median duration of 4.9 years for publications between 1887 and 1970 to 6.8 years between 1991 and 1994. Older age of onset was associated with shorter survival; the hazard ratio for patients with onset after 60 years was 1.8 (95% CI 1.4 to 2.3) compared with patients between 31 and 49 years. Cerebellar features were associated with marginally increased survival (6.1 years versus 5.4 years; p = 0.04). There were no difference in survival according to gender, parkinsonian, or pyramidal features or whether the patient was classified as striatonigral degeneration or olivopontocerebellar atrophy type. These results demonstrate the poor prognosis for patients with multiple system atrophy but may be biased toward the worst cases. Future research needs to recruit more representative samples. 相似文献