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   2849篇
  免费   11篇
  国内免费   1篇
电工技术   3篇
化学工业   50篇
金属工艺   2篇
机械仪表   8篇
建筑科学   17篇
能源动力   5篇
轻工业   64篇
水利工程   1篇
石油天然气   1篇
无线电   32篇
一般工业技术   42篇
冶金工业   2601篇
原子能技术   2篇
自动化技术   33篇
  2017年   6篇
  2015年   5篇
  2013年   17篇
  2012年   7篇
  2011年   7篇
  2010年   15篇
  2009年   8篇
  2008年   7篇
  2007年   10篇
  2006年   8篇
  2005年   12篇
  2004年   10篇
  2003年   14篇
  2002年   8篇
  2001年   6篇
  2000年   7篇
  1999年   75篇
  1998年   780篇
  1997年   422篇
  1996年   301篇
  1995年   175篇
  1994年   126篇
  1993年   169篇
  1992年   22篇
  1991年   23篇
  1990年   35篇
  1989年   36篇
  1988年   32篇
  1987年   16篇
  1986年   29篇
  1985年   21篇
  1984年   7篇
  1983年   5篇
  1982年   17篇
  1981年   20篇
  1980年   29篇
  1979年   7篇
  1978年   12篇
  1977年   84篇
  1976年   212篇
  1975年   4篇
  1974年   4篇
  1973年   4篇
  1972年   7篇
  1970年   3篇
  1969年   3篇
  1968年   3篇
  1966年   3篇
  1965年   4篇
  1964年   3篇
排序方式: 共有2861条查询结果,搜索用时 15 毫秒
991.
Recent reports indicate that combined anterior cruciate ligament/medial collateral ligament (ACL/MCL) knee injuries are usually associated with a lateral meniscus tear. In our center, snow skiing is the athletic activity most frequently associated with this double-ligament injury complex. A sports-specific analysis was undertaken to evaluate the hypothesis that the snow skiing ligament injury is different from similar injuries caused by other athletic activities. Of a total of 64 acute arthroscopically confirmed tears of both the MCL and ACL, 23 were caused by snow skiing and 41 by nonskiing activities. There were fewer lateral meniscus tears in skiers (43%) when compared with the nonskiers (88%). Skiers also had fewer medial meniscus tears (13%) than did nonskiers (37%). No medial meniscus tears occurred in the absence of a lateral meniscus tear. Although 78% of the skiers were women, only 12% of the nonskiers were women. Skiers were older (average age 35 years) than the nonskiers (average age 28 years). The right knee was injured almost twice as frequently as the left. These data suggest that the double (ACL/MCL) ligament injury in skiers might be distinctly different from that in nonskiers.  相似文献   
992.
During the past decade, considerable evidence has accrued regarding the immunologic uniqueness of human milk and of the important role that the immune system in human milk plays in protecting not only the mature, healthy newborn, but also the premature infant who is more prone to infections and the damage caused by inflammatory processes. However, there is a great deal more to learn about the prophylactic and therapeutic uses of human milk in low birth weight infants, including (1) the status of many of the host defense factors in preterm milk, (2) how to preserve the protective agents in human milk during processing and storage, (3) the dose and duration of treatment with human preterm or mature milk that will be needed to protect against a particular disorder, (4) whether non-maternal milk is as efficacious as maternal milk for these infants, and (5) in view of the concern of potential graft versus host reactions, whether it is desirable or contraindicated to maintain the leukocytes in human milk used to feed premature infants. These questions are not easily answered, but will be worthy considerations by neonatologists, clinical immunologists, epidemiologists, and others who are concerned with providing optimal nutritional/immunologic support for the premature infant.  相似文献   
993.
994.
995.
The article presents results of clinical trial of finlepsine-retard. Objectivized parameters characterizing the time course of psychopathologic symptoms were studied in certain concentrations of finlepsine and beta-endrofin in blood serum. Atypical maniac states do not easily respond to therapies but finlepsine-retard gives the modern psychopharmacotherapy a new horizon.  相似文献   
996.
We measured the apparent contrast and spatial frequency of a parafoveal Gabor signal located at the center of an array of Gabor signals as a function of both element density and the direction of contrast and spatial frequency of the surrounding elements. The target Gabor appeared lower in contrast and higher in spatial frequency when the elements were in close proximity, regardless of the direction of contrast and spatial frequency of the surrounding elements. Overall, the evidence suggests that the appearance of a parafoveal target is strongly affected by its visual context. These findings provide additional support for the existence of spatial interactions among neurons implicated in textural processing.  相似文献   
997.
In a previous study we showed that the levels of the intermediate filament proteins, cytokeratins 8, 18, and 19, in the nuclear matrix-intermediate filament (NM-IF) fraction from the hormone-dependent and estrogen receptor (ER)-positive human breast cancer cell line T-47D5 were regulated by estrogens. In contrast, estrogens did not regulate the cytokeratins in the NM-IF fraction of the hormone-independent and ER-positive cell line, T5-PRF. In this study, human breast cancer cells were treated with cis-diamminedichloroplatinum to cross-link protein to nuclear DNA in situ, and proteins bound to DNA were isolated. We show that cytokeratins 8, 18, and 19 of T-47D5 and T5-PRF were associated with nuclear DNA in situ. The levels of the cytokeratins 8, 18, and 19 bound to nuclear DNA or associated with the cytoskeleton of T-47D5 human breast cancer cells decreased when estrogens were depleted or the pure antiestrogen ICI 164,384 was added. In contrast, the cytokeratin levels associated with nuclear DNA or cytoskeleton were not significantly affected by estrogen withdrawal or antiestrogen administration in T5-PRF cells. These observations suggest that estrogen regulates the organization of nuclear DNA by rearrangement of the cytokeratin filament network in hormone-dependent, ER-positive human breast cancer cells and that this regulation is lost in hormone-independent, ER-positive breast cancer cells.  相似文献   
998.
999.
1000.
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