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   3284篇
  免费   3篇
电工技术   1篇
化学工业   34篇
金属工艺   4篇
机械仪表   1篇
建筑科学   4篇
矿业工程   2篇
能源动力   4篇
轻工业   14篇
无线电   16篇
一般工业技术   12篇
冶金工业   3178篇
原子能技术   2篇
自动化技术   15篇
  2023年   1篇
  2020年   2篇
  2018年   2篇
  2016年   2篇
  2015年   1篇
  2013年   4篇
  2012年   1篇
  2011年   6篇
  2010年   3篇
  2009年   3篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   5篇
  2004年   9篇
  2003年   7篇
  2002年   1篇
  2000年   1篇
  1999年   70篇
  1998年   928篇
  1997年   543篇
  1996年   392篇
  1995年   236篇
  1994年   163篇
  1993年   183篇
  1992年   20篇
  1991年   36篇
  1990年   28篇
  1989年   29篇
  1988年   24篇
  1987年   20篇
  1986年   18篇
  1985年   20篇
  1984年   1篇
  1983年   6篇
  1982年   20篇
  1981年   26篇
  1980年   35篇
  1979年   5篇
  1978年   10篇
  1977年   132篇
  1976年   259篇
  1975年   9篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1965年   1篇
  1964年   1篇
  1954年   1篇
排序方式: 共有3287条查询结果,搜索用时 203 毫秒
991.
Serum sialyl tranferase activity (STA) and protein bound carbohydrate were measured in hypercalcemic patients with surgically documented hyperparathyroidism (n = 15) or with cancer without skeletal metastases (n = 10). Precipitable protein-bound sialic acid and hexosamine, but not neutral hexoses or fucose were significantly (P less than 0.025) increased 40% and 21% respectively, in the perchlorate treated sera of cancer patients. Measurements of some specific serum glycoproteins by radial immunodiffusion assay were also different (P less than 0.05). Mean seromucoid protein was almost twice as great in the group with cancer (P less than 0.005), but four of these values overlapped those from the patients with hyperparathyroidism. The mean STA was 21.1 (range, 9.0-46.8) activity units in the patients with the cancer and 9.2 (range 1.0-17.8) in the patients with hyperparathyroidism (P less than 0.005). Six of the patients with cancer had values above the upper limit of the group with hyperparathyroidism. A discriminant function generated from these data correctly classified all the patients with hyperparathyroidism and 70% of those with cancer. Measurements of seromucoid and STA deserve further consideration as a way to discriminate some cases of hypercalcemia.  相似文献   
992.
More women of reproductive age are being sterilized. Some of these women regret the decision and subsequently request a reversal of sterilization, whereas others do not. This study was undertaken to develop a profile of easily definable traits of 159 women who requested a reversal of sterilization and compare it with that of 160 women who apparently were satisfied with sterilization. Statistically significant differences were found. Remarriage was the most common cause for regret among women in the group which requested reversal of sterilization. Women in this group married younger, completed their family earlier, and were sterilized at a younger age. These women had significantly fewer live children and had undergone more therapeutic abortions (p less than 0.005).  相似文献   
993.
994.
In the paper, the authors gave an analysis of some aspects of the metabolism in 90 patients, treated surgically for extrahepatic bile tract diseases (in 43 of them obstructive jaundice being noted), and the results of 34 experiments on white rats are summarized. Based on the conducted studies on acid-base balance, electrolyte metabolism and oxidative phosphorylation in hepatic mitochondria in the experiment under various kinds of anesthesia, some recommendations are given for including sodium oxybutyrate in anesthesia, the latter possessing a positive metabolic effect in patients with obstructive jaundice.  相似文献   
995.
996.
Nd:YAG laser was used to disrupt Descemet's membrane in rabbits in order to provoke the hypothetical release of angiogenic activity without a significant traumatic inflammation. Corneal vascularization was elicited only with simultaneous administration of heparin, which alone was unable to initiate the growth of new blood vessels. It is probable that basic fibroblast growth factor (bFGF) was released from its depot in Descemet's membrane and its critical concentration was saved by heparin. The importance of Descemet's membrane is highlighted by the fact that a similar lesion of midstroma could not induce angiogenesis even if aided by heparin. However, some other mechanisms cannot be ruled out, as bFGF acts in paracrine and amacrine mode only.  相似文献   
997.
BACKGROUND: Melanomas arising from the mucous membranes lining the respiratory, digestive, and genitourinary tracts are rare. Women are more commonly affected than are men, mainly because there is no male counterpart for vulvovaginal lesions. The mainstay of therapy is surgery, with little current use of adjuvant modalities in primary therapy. These lesions usually are advanced at initial presentation; consequently, the prognosis is poor, with 5-year survivals well below 50% in most series. METHODS: One hundred and nineteen patients with primary mucosal melanoma were reviewed. They represented 1.1% of the 10,393 melanoma patients seen at Duke University between 1970 and 1995. All data were obtained from the patients' clinic charts and computerized databases. RESULTS: There were 43 tumors arising from the head and neck region, 46 from the urogenital tract, and 30 from the anorectum. A female predominance was observed, with a female-to-male ratio of 2.7:1. All but five of the patients underwent resection with curative intent. Regional or distant metastases, or both, were encountered in 36 patients at the time of presentation. In patients with head and neck and urogenital tumors, local recurrences accounted for most of the treatment failures, whereas systemic recurrences were more common with tumors arising in the anorectum. The age and gender of the patient, anatomic site of origin of the tumor, clinical stage at initial presentation, and ulceration of the primary all clearly affected prognosis. Overall, the probabilities of being alive 1, 5, and 10 years after diagnosis were 80%, 29%, and 15%, respectively. CONCLUSIONS: Widely accepted classification systems are needed so that results from separate institutions can be compared adequately. Multi-institutional trials could help in delineating standardized therapeutic protocols and in establishing the potential roles of emerging modalities in the treatment of this subtype of melanoma.  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