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   323篇
  免费   3篇
电工技术   2篇
化学工业   32篇
金属工艺   9篇
机械仪表   1篇
建筑科学   19篇
矿业工程   1篇
能源动力   8篇
轻工业   17篇
无线电   30篇
一般工业技术   31篇
冶金工业   149篇
自动化技术   27篇
  2022年   2篇
  2021年   2篇
  2018年   4篇
  2016年   7篇
  2015年   2篇
  2014年   2篇
  2013年   10篇
  2012年   2篇
  2011年   10篇
  2010年   4篇
  2009年   7篇
  2008年   11篇
  2007年   8篇
  2006年   11篇
  2005年   9篇
  2004年   6篇
  2003年   8篇
  2002年   5篇
  2001年   5篇
  2000年   7篇
  1999年   8篇
  1998年   40篇
  1997年   20篇
  1996年   13篇
  1995年   13篇
  1994年   18篇
  1993年   10篇
  1992年   4篇
  1990年   4篇
  1989年   5篇
  1988年   4篇
  1987年   4篇
  1986年   2篇
  1985年   7篇
  1984年   2篇
  1983年   4篇
  1982年   3篇
  1981年   7篇
  1980年   3篇
  1979年   3篇
  1978年   4篇
  1977年   2篇
  1976年   7篇
  1973年   2篇
  1969年   3篇
  1967年   1篇
  1966年   1篇
  1963年   1篇
  1957年   1篇
  1956年   2篇
排序方式: 共有326条查询结果,搜索用时 0 毫秒
31.
Fuel poverty is perhaps the strongest adverse social impact resulting from the inefficient consumption of energy in the domestic sector. Despite considerable research examining the plight of those affected, there has been very little empirical work examining the relationship between fuel poverty and thermal comfort and the extent of indoor cold strain resulting from inadequately heated housing. Furthermore, the effects of fuel poverty on household occupancy have not been addressed formerly. This paper employs a new national household survey of Ireland—a country with a level of fuel poverty similar to Britain—to examine these key issues. Both self-reported and objective measures of thermal comfort are utilised, and the study pays particular attention to the age profile of those affected by thermal discomfort. The results show, inter alia, that two-thirds of fuel-poor householders demonstrate cold strain, and over half of elderly households endure inadequate ambient household temperatures during winter.  相似文献   
32.
Injection moulding of polymers is a well‐established technique for the production of increasingly complex articles, and residual molecular orientation is a matter of considerable interest. A single matrix of commercial atactic polystyrene was systematically blended with deuterated polystyrene chains of five different weight fractions and the orientation investigated using small angle neutron scattering (SANS), optical birefringence and thermal shrinkage. The strengths and limitations of the experimental techniques used to measure residual orientation are explored and highlighted the unique contribution of SANS to observe ensemble averaged molecular orientation using deuterated polymers. The residual molecular orientation was found to vary with the molecular weight of the deuterated chains with an increase with increasing molecular weight. The observed correlations lead to a better understanding of the processing parameters that influence the degree of residual orientation on the molecular scale. Such information is valuable in the selection of the polymer matrix, mould design, and processing conditions. POLYM. ENG. SCI., 58:1332–1341, 2018. © 2017 Society of Plastics Engineers  相似文献   
33.
Two months after colic surgery, subcutaneous masses were found on the ventral and lateral portions of the thorax of a 3-year-old Hanoverian-cross filly. Six months later, the filly was admitted for evaluation of severe lameness. Arthrocentesis of the tarsocrural joint yielded clotted sanguineous material; however, unusual multinucleated giant cells were seen. Radiography of the right tarsus revealed soft tissue opacity and degenerative joint disease. The filly was euthanatized to prevent further suffering. At necropsy, multiple soft-tissue masses were located throughout the fascial planes of the tarsi and in the subcutis of the ventral and lateral portions of the thorax. Neoplasms consisted primarily of a large number of mature well-differentiated T lymphocytes. On the basis of these findings, the diagnosis was cutaneous lymphoma with unusual involvement of periarticular tissues. Severe degenerative joint disease in the right tarsus did not appear to be associated with the tumors.  相似文献   
34.
Abstract  The paper presents the main findings of the London-based study, carried out as part of the ESRC project Groupwork with Computers. During this study, we attempted to identify the background and process factors which influence the success of groupwork with computers. The research used a multi-site case study design in six schools and involved eight groups of six mixed-sex, mixed-ability pupils (aged 9–12) undertaking three mathematics tasks, two using LOGO and one a database. Our main findings suggest that group settings are only successful in terms of both group outcome and learning, if the group structures their activity in particular and identifiable ways. These organisational styles and patterns of interaction themselves are conditional on interpersonal and social characteristics of the group and class.  相似文献   
35.
BRCA genes--bookmaking, fortunetelling, and medical care   总被引:1,自引:0,他引:1  
  相似文献   
36.
An iron-mediated oxidative stress caused by an increase of the intracellular pool of low molecular weight complex of iron (LMWC) can be observed with iron overloading or ethanol metabolism. The aim of this study was to determine whether nitric oxide (NO) behaved as a pro-oxidant or an antioxidant in such an iron-mediated oxidative stress in rat hepatocytes. The cells were set up in primary cultures and incubated with lipopolysaccharide (LPS) and gamma-interferon (IFN) for 18 hours to induce NO synthase and to trigger NO production. Then 20 micromol/L iron or 50 mmol/L ethanol were added. Oxidative stress was evaluated by measuring lipoperoxidation using two markers: malondialdehyde (MDA) and conjugated dienes. Simultaneously, NO production was followed by the quantitation of nitrites in the culture medium, dinitrosyl iron complexes (DNICs) and mononitrosyl iron complexes (MNICs) in intact hepatocytes. DNIC and MNIC, evaluated by electron paramagnetic resonance (EPR), corresponded to NO bound to iron-containing molecules and to free NO, respectively. In cultures preincubated with LPS and IFN before iron or ethanol addition, a net decrease of lipid peroxidation induced by either NO, iron, or ethanol was noted. Moreover, an elevation of iron-bound NO and a decrease of free NO were observed in these cultures compared with the cultures incubated with only LPS and IFN. These data support the idea that there is a relationship between the changes of NO pool and the inhibition of oxidative stress. In addition, using N(G)-monomethyl-L-arginine (L-NMMA), a NO synthase inhibitor, NO was shown to be involved in the inhibition of oxidative stress induced by iron or ethanol. Addition of the chelator of LMWC iron, deferiprone, was followed by the inhibition of the increase of iron-bound NO and the reincrease of lipid peroxidation extent, which was as high as in cultures incubated only with LPS and IFN. Thus LMWC iron appeared to be involved also in the inhibition of oxidative stress induced by NO. All the results favor the conclusion that NO acts as an antioxidant in iron-mediated oxidative stress in rat hepatocytes. NO reacted with LMWC iron to form inactive iron complexes unable to induce oxidative stress in rat hepatocytes. Thus NO played a critical role in protecting the liver from oxidative stress.  相似文献   
37.
Methods for calculating the heat balance of a furnace during the oxygen blow and for estimating the concurrent change in chromium analysis have been developed. The carbon content at the end of the blow can be estimated by means of these relationships when the initial composition and temperature of the bath, the amount of oxygen injected, and the duration of the oxidizing period are known. The relationships are used to evaluate the effects of oxygen input rate, chromium content, and temperature of the bath before the blow on metallic oxidation, oxygen usage, and temperature at the end of the blow.  相似文献   
38.
39.
40.
Abstract— The response of magnesia-partially-stabilized zirconia to cyclic loading was investigated using a purpose-built loading stage, designed to operate in the vacuum chamber of a scanning electron microscope. Crack tip/microstructural interactions, along with fatigue crack growth rates were studied and recorded photographically and via a video cassette recorder. For the experimental conditions examined, crack bridging, deflection and closure are discussed as possible mechanisms of fatigue crack growth resistance.  相似文献   
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