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   3219篇
  免费   0篇
电工技术   1篇
化学工业   16篇
金属工艺   5篇
建筑科学   2篇
矿业工程   2篇
能源动力   2篇
轻工业   5篇
无线电   4篇
一般工业技术   6篇
冶金工业   3166篇
原子能技术   1篇
自动化技术   9篇
  2020年   2篇
  2018年   1篇
  2015年   1篇
  2013年   2篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2009年   1篇
  2008年   1篇
  2007年   1篇
  2006年   3篇
  2005年   2篇
  2004年   4篇
  2003年   4篇
  1999年   70篇
  1998年   923篇
  1997年   538篇
  1996年   393篇
  1995年   235篇
  1994年   164篇
  1993年   183篇
  1992年   20篇
  1991年   33篇
  1990年   27篇
  1989年   30篇
  1988年   24篇
  1987年   19篇
  1986年   18篇
  1985年   19篇
  1983年   5篇
  1982年   19篇
  1981年   25篇
  1980年   33篇
  1979年   3篇
  1978年   10篇
  1977年   131篇
  1976年   258篇
  1975年   9篇
  1973年   1篇
  1965年   1篇
  1964年   1篇
  1954年   1篇
排序方式: 共有3219条查询结果,搜索用时 15 毫秒
91.
92.
93.
Early pregnancy factor (EPF) has been identified as a homologue of chaperonin 10 (cpn10) with immunosuppressive and growth factor properties. As a homologue of cpn10, it belongs to the heat shock family of proteins (hsp) but, unlike other members of this family, EPF is detected extracellularly. Early pregnancy factor was first discovered in pregnancy serum by the rosette inhibition test, and the novelty of its discovery was that its presence could diagnose pregnancy within 6-24 h of a fertile mating. As well as being a monitor of the presence of a viable embryo, it is necessary for embryonic survival. In this capacity it acts as both an immunosuppressant and growth factor. Early pregnancy factor is also a product of proliferating primary and neoplastic cells and functions as an autocrine growth factor both in vivo and in vitro. It has a modifying effect on the outcome of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. Early pregnancy factor is considered to be one of the major factors involved in the modification of multiple sclerosis observed during pregnancy.  相似文献   
94.
Non-accidental head injury, be it shaking, impact(s) or a combination of the two, is characterised by subdural and/or subarachnoid haemorrhages with retinal haemorrhages, but minimal or absent external cranio-facial trauma. The classical assault scenario depicts the infant being gripped around the head, face, chest and abdomen and shaken or being gripped by a limb and swung. This gripping might be expected to leave physical evidence in the form of bruising. A study was undertaken to establish the prevalence, distribution and pathological association of external bruising in 24 cases of fatal non-accidental head injury in children. At autopsy, 17 cases had new external bruises, 15 old external bruises and 13, a combination of both. However, seven (29%) cases showed no fresh external bruising and five (21%) showed no external bruising at all. Thus, external bruising may be absent in children with fatal intracranial injury. The face was shown to be the commonest site of bruising followed by the forehead and buttocks. Limb, chest and abdominal bruising were found to be uncommon. Retinal haemorrhages were confirmed in 23 (96%) cases. It is hypothesised that bruising, when present, may be a result of abuse in the form of punches and slaps rather than due to gripping during the assault. We discuss why gripping does not necessarily result in external bruising.  相似文献   
95.
OBJECTIVE: This study evaluated the biocompatibility of a resin-modified glass-ionomer material on monkey pulps. METHOD AND MATERIALS: Standardized Class V cavities were prepared in 112 teeth distributed in six healthy adult monkeys. The resin-modified glass-ionomer cement was placed in 24 nonexposed and 36 exposed pulps according to manufacturer's instructions. ZOE was used as a control in nonexposed pulps, while calcium hydroxide was used as a control for exposed pulps. Tissues were collected at 6 to 7, 21 to 27, and 90 to 97 days. After demineralization, the teeth were serially sectioned, stained, and observed by light microscopy. RESULTS: Except for one resin-modified glass-ionomer pulp at 6 days, there were no differences between the responses of nonexposed pulps to resin-modified glass-ionomer specimens and ZOE controls. In exposed pulps, eight of 36 resin-modified glass-ionomer pulps showed various grades of inflammatory response, all associated with stained bacteria. Pulpal healing was similar in both resin-modified glass-ionomer and calcium hydroxide direct-capped exposures. Twenty-two of 26 exposed pulps restored with the resin-modified glass-ionomer cement showed dentin bridge formation at 21 and 97 days. CONCLUSION: The resin-modified glass-ionomer material exhibited acceptable biologic compatibility in exposed and nonexposed cavities.  相似文献   
96.
97.
98.
99.
Debridement of nonviable tissue is crucial to optimal wound healing, which can be impaired unless all necrotic tissue, exudate, and metabolic wastes have been removed from the wound. Debridement methods are classified as sharp, mechanical, chemical, and autolytic. This article describes methods of debridement and their outcomes.  相似文献   
100.
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