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   135篇
  免费   0篇
电工技术   1篇
综合类   1篇
化学工业   3篇
金属工艺   1篇
矿业工程   1篇
轻工业   3篇
石油天然气   1篇
一般工业技术   4篇
冶金工业   119篇
自动化技术   1篇
  2017年   1篇
  2014年   1篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2007年   1篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  1999年   5篇
  1998年   33篇
  1997年   23篇
  1996年   12篇
  1995年   3篇
  1994年   9篇
  1993年   6篇
  1991年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1982年   3篇
  1981年   1篇
  1977年   4篇
  1976年   18篇
  1965年   1篇
排序方式: 共有135条查询结果,搜索用时 984 毫秒
41.
The seroprevalence of herpes simplex virus type 2 (HSV-2) infections among reproductive-aged women in the United States in prevalent. This article discusses HSV and how it effects the pregnant women and neonates. Management of the disease is reviewed, and recommendations for management of HSV during pregnancy are given.  相似文献   
42.
Numerical computer calculations for the thermal evolution of gas trapped by defects in extended subsurface layers of solids or coatings under a linear tampering schedule have been carried out. The dependence of the shape and location of thermal evolution transients upon the extension (width) of the initially trapped gas distribution has been found in comparison with the case of an initial planar concentration of trapped gas some lattice units below the surface. A comparative study has been performed concerning the effect of the thermal release mechanism (for ‘tandem’ and pure diffuisve mechanism) upon the thermal evolution transients having a given initial extended distribution and specific ratios of the migration energy to detrapping energy.  相似文献   
43.
Endothelin (ET)-1, alpha-melanocyte stimulating hormone (alpha-melanotropin; alpha-MSH), and basic fibroblast growth factor (bFGF) are keratinocyte-derived factors that interact synergistically to stimulate human melanocyte proliferation. ET-1 has a dose-dependent mitogenic effect on human melanocytes and a biphasic effect on melanogenesis: a stimulatory effect at subnanomolar concentrations, and an inhibitory effect at concentrations equal to or higher than 1 nM. Human melanocytes express ET B receptors. Brief treatment of melanocytes with ET-1 caused up-regulation of alpha-MSH receptor mRNA but did not alter ET B receptor mRNA level. ET-1 modulates the response of human melanocytes to UV rays (UVRs). Treatment of melanocytes with 10 nM ET-1 immediately after exposure to UVRs enabled them to overcome the G1 growth arrest. However, ET-1 did not inhibit p53 accumulation or p21(Waf-1/SDI-1/Cip-1) overexpression, nor did it reverse the hypophosphorylated state of pRb or the reduction in Bcl2 level in irradiated melanocytes. These results substantiate the role of ET-1 as a paracrine regulator that modulates the response of human melanocytes to UVRs.  相似文献   
44.
Most patients with carcinoma of the esophagus have advanced disease at presentation. Since cure is usually not possible, the goal of treatment is the palliation of dysphagia. Palliative modalities include bougies, balloons, stents, tumor probe, laser, surgery, chemotherapy, and radiation. In recent years, combined chemotherapy and radiation has shown promising results. However, the relief of dysphagia is slow and frequently incomplete. We compared the effectiveness of dilatation alone versus dilatation plus Nd-YAG laser therapy for the relief of dysphagia while assessing the role of chemotherapy and radiation as an adjunct to surgery. Fifteen patients with squamous cell carcinoma of esophagus who were deemed fit for intensive chemotherapy and radiation were randomized to receive either dilatation alone (N = 7) or dilatation plus laser (N = 8); the end-point for initial success was the passage of a 45 French Savary dilator, and the relief of dysphagia. At entry, 13 of these 15 patients were judged potentially resectable. However, after chemotherapy and radiation, only 3 of 13 (20%) patients could be offered surgery; the remainder were considered too poor a surgical risk. Follow-up was for 30 months, or until death. Further dilatations were performed as needed for relief of dysphagia. No difference was observed between the laser plus dilatation and the dilatation alone group with respect to the degree of dysphagia, weight record, quality of life index (Karnofsky score), or mortality rate. Our results indicate that in patients undergoing chemotherapy and radiation for esophageal carcinoma, dilatation alone provides adequate palliation of dysphagia, and in these patients, chemotherapy and radiation is a poor adjunct to surgical treatment.  相似文献   
45.
46.
Secretion of trypsin, chymotrypsin, lipase and amylase was measured in male rats under urethane anaesthesia using a method of continuous perfusion of the duodenum. Prolonged infusion of cholecystokinin-pancreozymin (CCK-PZ) over a period lasting 200-360 min was administered either alone or together with a submaximal dose of secretin (1 unit/100 g - 10 min). Infusion of CCK-PZ was carried out using maximal doses (1--1.5 unit/100 g - 10 min) with and without secretin. Supramaximal doses of CCK-PZ (2 and 4 units/100 g - 10 min) were used only in combination with secretin. In all experiments secretion of enzymes showed a triphasic pattern including an initial peak followed by a plateau secretion after 10--20 min (phase 1), a decreasing second phase and finally base-line secretion (phase 3), thus demonstrating exhaustion of enzyme output from the gland with time. With increasing and supramaximal dose of CCK-PZ the cumulative output of enzymes from start to baseline secretion decreased progressively. Under the same conditions the levels of peak and plateau secretion were lower, the duration of plateau secretion was longer and the decreasing phase of secretion was shortened. These features indicate inhibition of secretion with increasing supramaximal doses of CCK-PZ infusion. Whereas the proteolytic enzymes and lipase reacted in a parallel way always amylase secretion was sustained on a higher level, implicating an alternative pathway for secretion.  相似文献   
47.
48.
49.
A spectral-correlation analysis of electrical activity of the rabbit cerebral cortex was made with the use of Dnieper computer, after electrical stimulation (100-250 c/s) of the midbrain reticular formation, the thalamic nonspecific formations (midline nuclei) and different nuclei of the posterior part of the hypothalamic area (ventromedial and posterior hypothalamic nuclei and the lateral field). The background spectrograms were characterized by a high variability; their frequencies ranged from 0,5 to 12 c/s. Under the influence of the electrical stimulation of the indicated formations, a well-pronounced, dominating peak appeared in the spectrograms of the cortical EEG, in the band from 4 to 7 c/s, and the similarity of biopotentials in this rhythm increased. The experimental data show that enhancement of spatial synchronization of the cortical biopotentials under conditions of electrical stimulation of the indicated subcortical formations is based on increased rhythmic oscillations within the theta-band and on a greater coherence in this range.  相似文献   
50.
Diabetes mellitus is associated with typical patterns of long term vascular complications which vary with the organ involved. The microvascular kidney disease (Olgemoller and Schleicher, 1993) is characterized by thickening of the capillary basement membranes and increased deposition of extracellular matrix components (ECM), while loss of microvessels with subsequent neovascularisation is predominant in the eye and peripheral nerves. On the other hand macrovascular disease is characterized by accelerated atherosclerosis. These complications are dependent on long term hyperglycemia. Specific biochemical pathways linking hyperglycaemia to microvascular changes were proposed: the polyol pathway (Greene et al., 1987), non-enzymatic glycation of proteins (Brownlee et al., 1988), glucose autooxidation and oxidative stress (Hunt et al., 1990), hyperglycemic pseudohypoxia (Williamson et al., 1993) enhanced activation of protein kinase C by de novo-synthesis of diacyl glycerol (Lee et al., 1989; DeRubertis and Craven 1994) and others. These pathways are not mutually exclusive (Larkins and Dunlop, 1992; Pfeiffer and Schatz, 1992). They may be linked to alterations in the synthesis of growth factors particularly since atherosclerosis and angioneogenesis are associated with increased proliferation of endothelial and smooth muscle cells. Increased synthesis of ECM components is stimulated by growth factors like transforming growth factor beta (TGF beta) (Derynck et al., 1984) and insulin-like growth factor I (IGF-I) (Moran et al., 1991). This review will summarize some of the recent evidence for an involvement of growth factors in diabetic vascular complications and will attempt to assign their emergence in the sequence of events leading to vascular complications.  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