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   3400篇
  免费   4篇
  国内免费   1篇
电工技术   3篇
化学工业   28篇
金属工艺   5篇
机械仪表   2篇
建筑科学   13篇
能源动力   2篇
轻工业   10篇
水利工程   1篇
石油天然气   2篇
无线电   17篇
一般工业技术   32篇
冶金工业   3273篇
自动化技术   17篇
  2021年   1篇
  2017年   3篇
  2016年   1篇
  2015年   5篇
  2014年   3篇
  2013年   3篇
  2012年   4篇
  2011年   7篇
  2010年   10篇
  2009年   6篇
  2008年   4篇
  2007年   4篇
  2006年   3篇
  2005年   7篇
  2004年   4篇
  2003年   12篇
  2002年   6篇
  2001年   1篇
  2000年   8篇
  1999年   112篇
  1998年   1095篇
  1997年   604篇
  1996年   418篇
  1995年   214篇
  1994年   163篇
  1993年   203篇
  1992年   15篇
  1991年   40篇
  1990年   45篇
  1989年   39篇
  1988年   35篇
  1987年   30篇
  1986年   19篇
  1985年   21篇
  1983年   3篇
  1982年   10篇
  1981年   8篇
  1980年   27篇
  1979年   2篇
  1978年   4篇
  1977年   68篇
  1976年   126篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1966年   1篇
  1956年   1篇
  1954年   1篇
排序方式: 共有3405条查询结果,搜索用时 15 毫秒
941.
942.
943.
In the early part of the century, when adrenaline first became widely available, it was used in an uncontrolled manner and cases of ischaemic necrosis led to it falling into disfavour for hand surgery. Local anaesthesia with adrenaline is currently widely used for palmar and dorsal hand surgery but there remains a very deeply ingrained resistance to its use for digital anaesthesia. It is widely thought that it will cause irreversible digital artery vasospasm. This prospective study reports the effect of 2% lignocaine with 1:80,000 adrenaline digital blocks on various parameters of digital arterial blood flow in 100 consecutive patients. Our findings show that adrenaline only temporarily reduced digital blood flow. Perfusion of the digits persisted in every case.  相似文献   
944.
Monoclonal antibodies (mAbs) were used to identify and characterise epitopes of type 1 (SEF21) fimbriae of Salmonella enteritidis. The distribution of the epitopes among salmonellas and other enterobacteria was investigated, as well as the influence of growth media and temperatures on their expression. At least four different epitope clusters were identified on SEF21 fimbriae of S. enteritidis. Two of these clusters were associated with fimbrial haemagglutinins that were either common to all salmonellae tested, or restricted only to S. enteritidis and S. dublin. The four epitope clusters were identified on type 1 fimbriae of most Salmonella serotypes, as well as non-haemagglutinating type 2 fimbriae of S. pullorum and S. gallinarum, and on many other enterobacterial species. The expression of the epitopes was affected by growth conditions.  相似文献   
945.
Oleosins are amphipathic proteins associated with oil bodies in seeds. We purified the major 16,500 peanut oleosin by preparative SDS-PAGE. Autoradiography after SDS-PAGE separation of the iodinated oleosin revealed covalently bound oligomers with Mr of 21,000, 33,000, 44,000 and 51,000. The strong capacity of these oligomers to form aggregates and to be incorporated into large-sized detergent micelles was demonstrated by gel permeation and isoelectric focusing. A 50% ethanol concentration was necessary to elute the 16,500 oleosin from octyl groups in hydrophobic interaction chromatography showing its natural tendency to interact with lipid acyl chains. This oligomerization behavior in aqueous solution is an indirect reflection of the interactions that occur in the oil body.  相似文献   
946.
The use of dental appliances in the treatment of patients with snoring and obstructive sleep apnoea is an important treatment modality for those patients not severe enough for continuous positive airway pressure (CPAP) or who cannot tolerate this form of treatment. A mandibular advancement splint has been specifically designed to eliminate snoring and obstructive sleep apnoea. The appliance's design parameters included ease of insertion, comfort, and maximum effectiveness. Customised appliances have been designed for dentate, semi-dentate, and edentulous patients. To date, over 100 appliances have been used with a symptomatic improvement in snoring and well-being in over 80 percent of patients. Dental appliances for the treatment of snoring and obstructive sleep apnoea are simple, cost effective, and reversible.  相似文献   
947.
948.
Iodine-131-metaiodobenzylguanidine (MIBG) is used in the treatment of carcinoid tumors. Temporary palliation with complete subjective symptomatic response has been reported in these patients. This treatment is usually well tolerated and side-effects are generally limited to nausea, mild hepatic toxicity with spontaneous recovery and temporary myelosuppression. Our case report shows that repeated treatment with [131I]MIBG in a patient with extensive carcinoid liver metastasis may cause severe hepatic toxicity leading to death. Factors such as concomitant use of 5-fluorouracil and the progressive nature of the disease may have contributed to this event.  相似文献   
949.
950.
Opioid receptors are regulated within minutes after activation by G protein-coupled receptor kinase-mediated phosphorylation and dynamin-dependent endocytosis. We addressed the question of whether phosphorylation is required for opioid receptor endocytosis by examining a functional, truncated mutant delta opioid receptor (DOR344T), which is missing phosphorylation sites located in the carboxyl-terminal cytoplasmic domain. DOR344T receptors expressed in Chinese hamster ovary cells remained predominantly in the plasma membrane, even in the presence of saturating concentrations of agonist, consistent with previous studies demonstrating strongly inhibited endocytosis of truncated receptors in this cell type. In marked contrast, DOR344T receptors expressed at similar levels in human embryonal kidney (HEK) 293 cells exhibited rapid, ligand-induced internalization either in the presence of peptide (DADLE) or alkaloid (etorphine) agonist. Quantitative assays using ELISA and flow cytometric techniques indicated that DOR344T receptors were endocytosed in HEK293 cells with similarly rapid kinetics as full-length DOR (t1/2 < 10 min), and both full-length DOR and DOR344T mutant receptors were endocytosed by a dynamin-dependent mechanism involving clathrin-coated pits. Nevertheless, DOR344T receptors failed to undergo any detectable constitutive or agonist-induced phosphorylation in the same cells in which dynamin-dependent endocytosis was observed. These findings establish the first example of a G protein-coupled receptor that does not require phosphorylation to undergo dynamin-dependent endocytosis, and they suggest that significant cell type-specific differences exist in the biochemical requirements for ligand-induced concentration of opioid receptors in clathrin-coated pits.  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