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   1189篇
  免费   3篇
电工技术   1篇
化学工业   16篇
金属工艺   1篇
机械仪表   3篇
建筑科学   1篇
轻工业   3篇
水利工程   1篇
一般工业技术   11篇
冶金工业   1143篇
原子能技术   7篇
自动化技术   5篇
  2019年   2篇
  2017年   2篇
  2016年   1篇
  2014年   3篇
  2013年   1篇
  2012年   1篇
  2011年   3篇
  2008年   1篇
  2007年   1篇
  2006年   1篇
  2005年   2篇
  2004年   3篇
  2003年   3篇
  2001年   5篇
  2000年   1篇
  1999年   32篇
  1998年   350篇
  1997年   200篇
  1996年   135篇
  1995年   53篇
  1994年   67篇
  1993年   69篇
  1992年   9篇
  1991年   22篇
  1990年   9篇
  1989年   21篇
  1988年   26篇
  1987年   12篇
  1986年   24篇
  1985年   15篇
  1983年   5篇
  1982年   2篇
  1981年   7篇
  1980年   10篇
  1979年   2篇
  1978年   2篇
  1977年   29篇
  1976年   52篇
  1975年   3篇
  1974年   1篇
  1971年   1篇
  1968年   1篇
  1967年   1篇
  1955年   1篇
  1954年   1篇
排序方式: 共有1192条查询结果,搜索用时 15 毫秒
1.
2.
3.
JN Nasedkin 《Canadian Metallurgical Quarterly》1998,19(7):671-4, 676, 678 passim; quiz 684
The directed shrinkage approach was developed to create sealed tooth-restoration interfaces in posterior composite restorations. Creative application of this technique can result in foundations that are suitable for a variety of applications, including salvaging broken-down teeth and supporting free-hand restorations. The sealed interface reduces microleakage and postoperative tooth sensitivity. The components required for this technique are readily available and are usually part of the practice's armamentarium.  相似文献   
4.
There is growing evidence that face recognition is "special" but less certainty concerning the way in which it is special. The authors review and compare previous proposals and their own more recent hypothesis, that faces are recognized "holistically" (i.e., using relatively less part decomposition than other types of objects). This hypothesis, which can account for a variety of data from experiments on face memory, was tested with 4 new experiments on face perception. A selective attention paradigm and a masking paradigm were used to compare the perception of faces with the perception of inverted faces, words, and houses. Evidence was found of relatively less part-based shape representation for faces. The literatures on machine vision and single unit recording in monkey temporal cortex are also reviewed for converging evidence on face representation. The neuropsychological literature is reviewed for-evidence on the question of whether face representation differs in degree or kind from the representation of other types of objects.  相似文献   
5.
BACKGROUND: Clinical manifestations and course of sickle-cell anemia are variable. Knowledge about the factors, possibly geographic, that influence prognosis are still scanty. POPULATION AND METHODS: Data of hospitalization and management of children with sickle-cell disease were studied during two years (1992-1993) in the Pediatric Unit of Libreville Hospital. They concerned 205 admissions of 171 children and 131 outpatients. RESULTS: The main causes of hospitalization were: acute anemia (36 cases before the age of 5 years); painful crisis whose frequency increased with age (23% before 5 years, 35% between 5 and 10, 42% after 10 years); infections, essentially pulmonary occurring early, and bone infections at any age. Eight children died (because a complication of their disease). Among the 131 outpatients, half were detected because pyrexia, anemia and/or more often "hand-foot syndrome". More than 60% had hepatomegaly, one third still had splenomegaly after five years of age and more than one third was icteric. More than half children older than ten years had growth disorders. Mean hemoglobin level was 7 g/dL. 21 of the 83 tested children for HBsAg were positive and only one out of 79 was positive for HIV. CONCLUSIONS: Clinical manifestations and course of sickle-cell anemia in our patients are similar to those reported in Congolese children. Genetic and environmental factors may be responsible for differences with children from other, in particular French, cohorts.  相似文献   
6.
Disc disease is benign and not life threatening. Its long-term prognosis is uncertain, and spontaneous recoveries are common. The decision to perform surgery thus carries with it a heavy responsibility to provide safe treatment. "Good safe surgical technique" is essential, but it is much more than a well-rehearsed routine procedure. From preoperative evaluation to surgery to postoperative care, the surgeon must look ahead to problems that might arise. Where anticipated risks cannot be avoided, they should be minimized, and when adverse events occur, active recognition will lead to early and accurate management.  相似文献   
7.
8.
9.
10.
In stalk parenchyma tissue of WF9 X 38-11 single corn (Zea mays L.), there was a per cell increase in RNA synthesis and a slight increase in total RNA as cells became older. In cob parenchyma tissue of WF9 X 38-11 single cross corn, both total RNA content and RNA synthesis per cell decreased with the age of cells. In first developed leaf tissue of FR43 X FR14A single cross corn, RNA synthesis increased steadily but only slightly over its life span. The pattern of RNA synthesis and destruction in senescing leaf tissue of seedlings and two sources of parenchyma tissue of maturing plants appeared to differ.  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