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   2176篇
  免费   0篇
  国内免费   1篇
电工技术   4篇
化学工业   8篇
机械仪表   2篇
建筑科学   6篇
能源动力   4篇
轻工业   15篇
水利工程   1篇
无线电   6篇
一般工业技术   18篇
冶金工业   2096篇
原子能技术   1篇
自动化技术   16篇
  2022年   1篇
  2021年   2篇
  2020年   1篇
  2019年   4篇
  2015年   1篇
  2014年   2篇
  2013年   8篇
  2012年   2篇
  2011年   6篇
  2010年   5篇
  2009年   2篇
  2008年   5篇
  2007年   5篇
  2006年   5篇
  2005年   1篇
  2004年   2篇
  2003年   5篇
  2002年   5篇
  2001年   2篇
  2000年   1篇
  1999年   76篇
  1998年   694篇
  1997年   398篇
  1996年   246篇
  1995年   139篇
  1994年   112篇
  1993年   127篇
  1992年   17篇
  1991年   21篇
  1990年   15篇
  1989年   23篇
  1988年   24篇
  1987年   19篇
  1986年   11篇
  1985年   13篇
  1983年   3篇
  1982年   12篇
  1981年   8篇
  1980年   13篇
  1978年   4篇
  1977年   41篇
  1976年   91篇
  1975年   2篇
  1973年   1篇
  1971年   1篇
  1955年   1篇
排序方式: 共有2177条查询结果,搜索用时 343 毫秒
981.
OBJECTIVE: This study examined occupational therapists' use of the occupational form of goal setting as therapy and its impact on clients. METHOD: The study method was qualitative, using participant observation and interviewing as the main source of data. RESULTS: The findings illustrated that therapists work both to give substance to the occupational form and to create the context of an implied narrative that imbues it with particular meanings. Simultaneously, clients' experience of meaning is influenced by a personal volitional narrative. When the two narratives do not coincide, therapists' efforts to maintain the occupational form intensify as they encourage clients toward attitudes and performances that do not resonate with the clients' experience of reality. CONCLUSION: The findings underscore the importance of recognizing that occupational forms are embedded in social processes and perspectives that inevitably come into play when occupational forms are used as therapy.  相似文献   
982.
Human dermal fibroblast and human epidermal keratinocyte survival was examined under various conditions in organ culture. Using cell recovery from organ-cultured tissue as the criterion, it was observed that no keratinocytes and few fibroblasts survived incubation for 10-12 days in serum-free basal medium containing a low level (0.15 mM) of extracellular Ca2+. Increasing the extracellular Ca2+ concentration to 1.4 mM or treating the tissue with 3 microM retinoic acid (RA) under low Ca2+ conditions resulted in increased keratinocyte and fibroblast survival; the two treatments together were more effective than either treatment alone. The same treatments preserved fibroblast survival when pieces of isolated dermal tissue were incubated in organ culture and also supported fibroblast survival in monolayer culture. These findings indicate that recovery of keratinocytes and fibroblasts from skin after maintenance in organ culture provides a simple but definitive measure of the viability of the major cellular elements present in the tissue. These findings suggest that RA treatment enhances survival of both fibroblasts and keratinocytes and that these effects of RA can be seen at physiological Ca2+ concentrations as well as at suboptimal levels of extracellular Ca2+. Finally, these results indicate that the dermis is a direct target of RA.  相似文献   
983.
984.
985.
986.
987.
Ten patients who suffered iatrogenic injury to a vertebral artery during anterior cervical decompression were reviewed to assess the mechanisms of injury, their operative management, and the subsequent outcome. All had been undergoing a partial vertebral body resection for spondylitic radiculopathy or myelopathy (4), tumour (2), ossification of the posterior longitudinal ligament (1), nonunion of a fracture (2), or osteomyelitis (1). The use of an air drill had been responsible for most injuries. The final control of haemorrhage had been by tamponade (3), direct exposure and electrocoagulation (1), transosseous suture (2), open suture (1), or open placement of a haemostatic clip (3). Five patients had postoperative neurological deficits, but most of them resolved. We found direct arterial exposure and control to be safe, quick and reliable. Careful use of the air drill, particularly in pathologically weakened bone, as in infection or tumour, is essential. Arterial injury is best avoided by a thorough knowledge of the anatomical relationships of the artery, the spinal canal, and the vertebral body.  相似文献   
988.
989.
Pseudomonas syringae subsp. savastanoi causes tumors on olive and oleander by producing the plant growth regulators indoleacetic acid (IAA) and cytokinins following infection of the plant. The contribution of IAA production to the ability of P. syringae subsp. savastanoi to grow and survive in oleander leaf tissue was studied. Bacterial strains differing only with respect to IAA production were characterized. Growth and survival of wild-type and two mutant strains of P. syringae subsp. savastanoi in oleander leaf tissue were monitored by weekly colony counts and IAA plate assays. Growth rate of the three strains in culture and in planta did not differ significantly. However, the wild-type strain reached a higher population density and maintained its maximum density at least 9 weeks longer than either mutant population. An insertion mutant containing the IAA plasmid (pIAA), but incapable of IAA production, did not maintain a higher population density than a strain cured of the IAA plasmid. The pIAA-cured strain maintained a higher population density when coinoculated with an IAA-producing strain than when inoculated alone. These results suggest that IAA production may contribute to the fitness of P. syringae subsp. savastanoi in oleander tissue and that the iaa operon alone may be responsible for the competitive advantage of cells harboring pIAA.  相似文献   
990.
Thirteen methods for computing binomial confidence intervals are compared based on their coverage properties, widths and errors relative to exact limits. The use of the standard textbook method, x/n +/- 1.96 square root of [(x/n)(1-x/n)/n], or its continuity corrected version, is strongly discouraged. A commonly cited rule of thumb stating that alternatives to exact methods may be used when the estimated proportion p is such that np and n(1(-)p) both exceed 5 does not ensure adequate accuracy. Score limits are easily calculated from closed form solutions to quadratic equations and can be used at all times. Based on coverage functions, the continuity corrected score method is recommended over exact methods. Its conservative nature should be kept in mind, as should the wider fluctuation of actual coverage that accompanies omission of the continuity correction.  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