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   271篇
  免费   1篇
电工技术   5篇
化学工业   8篇
金属工艺   2篇
机械仪表   2篇
建筑科学   33篇
矿业工程   1篇
轻工业   10篇
水利工程   2篇
石油天然气   2篇
无线电   2篇
一般工业技术   21篇
冶金工业   181篇
自动化技术   3篇
  2024年   2篇
  2022年   1篇
  2018年   1篇
  2017年   1篇
  2015年   2篇
  2014年   2篇
  2013年   14篇
  2012年   1篇
  2011年   3篇
  2010年   5篇
  2009年   10篇
  2008年   10篇
  2007年   7篇
  2006年   4篇
  2005年   1篇
  2004年   5篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  1999年   4篇
  1998年   63篇
  1997年   28篇
  1996年   25篇
  1995年   17篇
  1994年   13篇
  1993年   8篇
  1992年   3篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1977年   7篇
  1976年   8篇
  1972年   1篇
  1970年   1篇
排序方式: 共有272条查询结果,搜索用时 62 毫秒
81.
82.
The release of certain cytokines, e.g. tumour necrosis factor (TNF)-alpha, in the amniotic fluid has been suggested to be a cause of preterm birth. The predisposition to excessive liberation of cytokines from peripheral leukocytes has been shown to depend partly on the individual's HLA-DR genotype. The HLA-DR1 and -DR3 alleles have previously been reported as being associated with a TNF-alpha high responder status and have also been associated with unexplained recurrent spontaneous abortions. In the present study, HLA-DR typing was performed in 10 women who had experienced recurrent very early preterm births resulting in perinatal death, or late spontaneous abortions under a clinical picture resembling that traditionally attributed to cervical incompetence. All patients had had at least one mid-trimester miscarriage in spite of the insertion of a cervical cerclage. Nine out of 10 (90%) patients had the HLA-DR phenotypes DR1 and/or DR3 compared with 37% in the background population (P < 0.005). The results suggest that HLA-DR-associated immunological factors might play a part in recurrent late spontaneous abortions and extremely preterm births under a cervical incompetence-like picture, at least in the subset of cases not treatable by cervical cerclage.  相似文献   
83.
The activity of 63 neurones of the dorsal hippocampus field CA1 was studied in unrestrained rabbits in different behaviour and in the course of repetitive afferent stimulation. It has been found that changes in the mean frequency of spontaneous activity of most neurones (90%) correlate with the kind of the animal's behaviour. Replacement of calm alertness by an active state is primarily attended with enhanced mean frequency of firing. Two types of response dynamics to a repetitive stimulation were revealed: 1) successive decrease of reaction and 2) gradual augmentation and subsequent drop. As stimulation went on most of the neurones revealed a change in the nature of responses: diffuse phasic and tonic reactions were replaced by structured responses of a specific type. The data obtained are regarded as proof of the hippocampus involvement in the organization of integrated orienting behaviour.  相似文献   
84.
Diffuse myocarditis with alteation and proliferation was described in adult BALB/c mice infected with Coxsacke A13 virus. A marked tendency to sclerotic processes 30 to 60 days after the infection was noted; this can underly the reduction of the functional activity of the myocardium and lead to the development of cardiomyopathy.  相似文献   
85.
Controversially, Neil Spiller risks the fallout and confronts the trend for multidisciplinary architectural collaborations head-on. He explains why he believes corporate team management can only lead to the mundane and the mediocre, denying individuality, creativity and vision. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
86.
87.
Life cycle assessment is a technical management tool that can help quantify the environmental impacts associated with products or processes. For example, it relates the energy and materials used or during the manufacture, distribution, operation and disposal of a product to their impact on the environment as fossil reserve depletion, ozone depletion, landfill volume, etc. This paper focuses on the practicalities of conducting a life cycle assessment on a semiconductor communications laser  相似文献   
88.
89.
The antioxidant properties of the carotenoid lycopene were compared in three different model oxidative systems. In egg yolk liposomes, in the presence of 2.5 mM FeSO4 and 200 mM ascorbate, lycopene, alpha-tocopherol, and beta-carotene inhibited the accumulation of lipid peroxidation products reacting with 2-thiobarbituric acid (TBARS) in a dose-dependent mode, with the concentration of half-inhibition being 80, 30 and 130 mM, respectively. In the liposomes subjected to illumination with a He-Ne laser (632.8 nm) at a dose of 10.5 J/cm2, in the presence of 32.5 micrograms/ml hematoporphyrin derivatives (Fotogem, NIOPIC, Russia) TBARS accumulated, and this effect was inhibited by lycopene, alpha-tocopherol, and dihydroquercetin with approximately equal efficiencies (the half-inhibition concentrations were 10(-5) mM). In both systems studied, sodium azide at a concentration of 10 mM inhibited the TBARS accumulation by no more than 20%. Apparently, the inhibitory action of not only alpha-tocopherol, but also beta-carotene and lycopene was the result of their antiradical action, rather than quenching of the singlet oxygen in an aqueous medium. The introduction of lycopene, as well as beta-carotene in liposomes subjected to Fe(2+)-induced lipid peroxidation decreased the chemiluminescence (CL) intensity at the stage of CL slow flash, with no essential influence on the lag period. These data suggest that the effect of lycopene on lipid peroxidation was the result of its interaction with free radicals rather than chelating ferrous ions. The antiradical activity of lycopene was also confirmed by the method of luminol photochemiluminescence (PCL). Lycopene increased the PCL lag period (L) and decreased the PCL amplitude (A), which implies its antiradical and SOD-like activity in this system.  相似文献   
90.
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