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   831篇
  免费   19篇
电工技术   2篇
综合类   1篇
化学工业   73篇
金属工艺   7篇
机械仪表   6篇
建筑科学   16篇
矿业工程   1篇
能源动力   9篇
轻工业   19篇
水利工程   2篇
石油天然气   2篇
无线电   36篇
一般工业技术   53篇
冶金工业   587篇
原子能技术   2篇
自动化技术   34篇
  2023年   4篇
  2022年   10篇
  2021年   15篇
  2020年   6篇
  2019年   6篇
  2018年   9篇
  2017年   8篇
  2016年   16篇
  2015年   3篇
  2014年   8篇
  2013年   17篇
  2012年   15篇
  2011年   20篇
  2010年   11篇
  2009年   14篇
  2008年   19篇
  2007年   10篇
  2006年   9篇
  2005年   6篇
  2004年   3篇
  2003年   4篇
  2002年   3篇
  2001年   3篇
  1999年   26篇
  1998年   165篇
  1997年   100篇
  1996年   73篇
  1995年   63篇
  1994年   33篇
  1993年   36篇
  1992年   8篇
  1991年   7篇
  1990年   5篇
  1989年   10篇
  1988年   13篇
  1987年   7篇
  1986年   6篇
  1985年   10篇
  1984年   1篇
  1982年   2篇
  1981年   2篇
  1980年   8篇
  1979年   2篇
  1978年   3篇
  1977年   15篇
  1976年   31篇
  1975年   1篇
  1973年   1篇
  1963年   1篇
  1955年   1篇
排序方式: 共有850条查询结果,搜索用时 15 毫秒
41.
To create a programming environment for contract dispute resolution, we propose an extension of assumption-based argumentation into modular assumption-based argumentation in which different modules of argumentation representing different knowledge bases for reasoning about beliefs and facts and for representation and reasoning with the legal doctrines could be built and assembled together. A distinct novel feature of modular argumentation in compare with other modular logic-based systems like Prolog is that it allows references to different semantics in the same module at the same time, a feature critically important for application of argumentation in legal domains like contract dispute resolution where the outcomes of court cases often depend on whether credulous or skeptical modes of reasoning were applied by the contract parties. We apply the new framework to model the doctrines of contract breach and mutual mistake.  相似文献   
42.
通过古希腊三种柱式的现存实例以及形象生动的少女柱、神庙等建筑遗迹,简要介绍古代希腊雅典和特尔菲两地在石材建筑造型上的取得的辉煌成就。  相似文献   
43.
Oestradiol regulates reproductive physiology and cardiovascular health in women. In the endometrium of ovariectomized ewes, previous work demonstrated that a single dose of oestradiol (50 microg) up-regulates oestrogen receptor-alpha (ER) and progesterone receptor (PR) gene expression within 24 h. Here we compared responses to different doses of oestradiol and different dosing regimens in two diverse tissues: endometrium and liver. ER, c-fos, cyclophilin and glyceraldehyde phosphate dehydrogenase (GAPDH) mRNA concentrations were analyzed on replicate RNA slot blots in both tissues, while PR and apolipoprotein AI (apo AI) mRNA concentrations were only analyzed in endometrium or liver, respectively. Along with ER mRNA, oestradiol strongly up-regulated GAPDH and cyclophilin mRNA concentrations in endometrium. In liver, however, oestradiol down-regulated them, along with apo AI mRNA. Responses to different doses and dose regimens, including repeated 50 microg doses, were similar to those evoked by a single 50 microg dose of oestradiol. Thus, oestradiol appears to have all-or-none effects which include up-regulation of ER, cyclophilin and GAPDH gene expression in endometrium and down-regulation of ER, apo AI, cyclophilin and GAPDH gene expression in liver. These results illustrate the sharp contrast between two mammalian tissues in their responses to physiological levels of oestradiol.  相似文献   
44.
45.
46.
The methylation of phosphatidylethanolamine is an auxiliary pathway for phosphatidylcholine biosynthesis in liver. Two forms of the enzyme, phosphatidylethanolamine N-methyltransferase, which catalyses this reaction, are located on the endoplasmic reticulum and mitochondria-associated membranes. Both forms are encoded by a single murine gene, Pempt, located on chromosome 11. The expression of the gene begins at birth. An inverse relationship exists between the rate of liver growth and the expression of phosphatidylethanolamine N-methyltransferase. However, disruption of the Pempt gene does not alter liver growth in mice or cause any other obvious phenotype.  相似文献   
47.
Tetanus has become an uncommon disease in developed countries. Tetanus is caused by exotoxins from the bacteria Clostridium tetani. This microbe, which is obligate anaerobe, is present in soil, and animal and human faeces. The condition usually appears after contamination of wounds. However, reports have been published of tetanus occurring after both acute and selective gastrointestinal surgery. We present a case of severe postoperative tetanus in a 57 year-old woman who underwent bowel resection after strangulation of the ileum. The patient was treated on an intensive care unit and was artificially ventilated for 64 days. Seven months later she had fully recovered. Clinical presentation, diagnosis, treatment, and complications are discussed in the report. The diagnosis of tetanus is made by clinical observation. Nowadays, lack of suspicion of this condition may cause delay in administering proper treatment. Women and older men are often inadequately immunized. Doctors should therefore examine the immunization status of these groups of patients regularly.  相似文献   
48.
One characteristic of glycoproteins is that they are separated by two-dimensional electrophoresis (2-D PAGE) into typical 'trains' of protein spots which separate on the basis of different isoelectric point (pI) and/or molecular mass. The pattern of these trains often varies in development and disease. While the isoforms differ both in the number of sites of glycosylation and the types of carbohydrate attached to the protein, classical methods of glycan analysis are insensitive at the levels typically separated by 2-D PAGE. Developments in mass spectrometry technologies have enabled the characterization of most of the oligosaccharide attributes to be determined on picomole amounts of protein. These techniques are beginning to allow the glycoform heterogeneity on 2-D separated glycoproteins to be analyzed.  相似文献   
49.
The elastic properties of carotid arteries of spontaneously hypertensive rats (SHR) and normotensive controls (Wistar-Kyoto rats [WKY]) were examined in vivo, in situ, and in vitro. The changes of internal diameter were measured with a high-resolution A-mode echo-tracking device simultaneously with the intra-arterial pressure at the carotid. The internal diameter at mean arterial blood pressure (MBP) was substantially smaller in vitro than in vivo in SHR (-33.8%) and WKY (-48.3%). The arterial distensibility was lower in vitro in all arteries compared with in vivo conditions (SHR, -30.1%; WKY, -60.4%; at MBP) despite a reduced incremental elastic modulus in vitro (SHR, -56.9%; WKY, -45.1%; at MBP). However, the in vitro and in vivo measurements show consistent elastic behavior of the carotid arteries between both strains of rats. Carotid arteries from WKY were also examined in situ. Although no significant reduction in internal diameter could be observed in situ, distensibility was dramatically decreased (-87% at MBP). These results emphasize the importance of considering the original vascular geometry when determining elastic properties of arteries. We conclude that experimental conditions are likely to be a critical determinant for the assessment of the mechanical properties of conduit vessels.  相似文献   
50.
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