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   1391篇
  免费   1篇
  国内免费   2篇
化学工业   3篇
金属工艺   1篇
轻工业   3篇
一般工业技术   3篇
冶金工业   1383篇
自动化技术   1篇
  2016年   1篇
  2013年   4篇
  2007年   1篇
  2006年   1篇
  2003年   3篇
  2000年   1篇
  1999年   31篇
  1998年   478篇
  1997年   264篇
  1996年   153篇
  1995年   93篇
  1994年   61篇
  1993年   88篇
  1992年   17篇
  1991年   8篇
  1990年   8篇
  1989年   10篇
  1988年   5篇
  1987年   13篇
  1986年   8篇
  1985年   3篇
  1983年   6篇
  1982年   7篇
  1981年   2篇
  1980年   13篇
  1979年   2篇
  1978年   3篇
  1977年   38篇
  1976年   70篇
  1975年   1篇
  1955年   1篇
排序方式: 共有1394条查询结果,搜索用时 15 毫秒
61.
The aim of the study was to identify factors of decisive importance for women's motivation to perform breast self-examination (BSE), which could form the basis of an intervention programme. Interviews were conducted in 1994 with 48 women focusing on four different areas: 1) why the women examined did not examine their breasts, 2) the influence of their upbringing, 3) information or education previously received about the method of examination, and 4) other types of self-care. The findings were summarized under the following categories: feelings, experiences, and lifestyle. Anxiety/fear of discovering a lump and faith/trust in one's own ability to perform the examination were dominating factors influencing the practice or non-practice of BSE. However, there was a general need for knowledge, theoretical as well as practical, among the women studied. They also needed help to identify a strategy to enable them to remember to perform the examination. In order to make BSE a habit, education about BSE ought to be provided to girls at school. The important role of nurses in teaching women to examine their breasts themselves and in reminding them to perform the examination was emphasized.  相似文献   
62.
The A3 adenosine receptor is one of the four adenosine receptors which have thus far been identified. Cloning of the A3 receptor from animal species such as rat, sheep and human has shown that there are interspecies differences in its peripheral distribution, and binding affinity for various adenosine receptor ligands. The adenosine derivative, 4-aminobenzyl-5'-N-methylcarboxamidoadenosine (AB-MECA), is a potent A3 receptor agonist which is used as a reference drug. In this report we have characterized the binding of selected adenosine receptor agonists and antagonists to HEK 293 cells transfected with the human A3 adenosine receptor using [125I]AB-MECA as radioligand. HE-NECA and NECA were the most potent compounds showing Ki values in the low nanomolar range, while the recently discovered non-xanthine A2A receptor antagonists ZM 241385, SCH 58261 and SCH 63390 showed affinity values in the micromolar range. These data further indicate the need to examine the affinity of new adenosine receptor ligands directly in human A3 receptors.  相似文献   
63.
64.
Two new withanolides (steroidal lactones) named coagulin F [27-hydroxy-14,20-epoxy-1-oxo-(22R)-witha-3,5,24-trienolide] (1) and coagulin G [17beta,27-dihydroxy-14,20-epoxy-1-oxo-(22R)-witha-2,5, 24-trienolide] (2) were isolated from the whole plant of Withania coagulans, and their structures were deduced by spectral analysis.  相似文献   
65.
Intracerebral infection of mice aged 2-3 days with hepatitis C virus (HCV) from chronically infected suckling mouse brain cultures and porcine embryo cells resulted in the death of animals after 12-14 days. Repeated passages of HCV in animals decreased the incubation period to just 3-4 days. Blood serum of surviving mice collected during the 4th week postinfection contained antiHCV antibodies detected by enzyme immunoassay and hemagglutination inhibition test. The results are proof of creation of a new in vivo model of experimental HCV infection.  相似文献   
66.
Cryoprecipitates, in addition to containing factor VIII, contain about one third of the fibrinogen in the plasma from which they were derived. This fibrinogen is functional, as established by successfully preparing two congenital hypofibrinogenemics for major surgery by infusing cryoprecipitates. Cryoprecipitates and platelet concentrates are also used for patients with low levels caused by disseminated intravascular coagulation (DIC). We feel that these patients benefit not only from the factor VIII in the cryoprecipitates, but from the fibrinogen, which adds its support to the fibrinogen in platelet infusions, plasma, and whole blood. Such support makes it possible to heparinize such patients more heavily than would be safe without such preparation. The authors report three patients with severe and life-endangering DIC who were heavily heparinized, and supported with cryoprecipitates, as well as other blood fractions. Response to this therapy was excellent.  相似文献   
67.
68.
69.
Human von Willebrand factor (vWF) is synthesized as an extra large polymer; then, it is converted to lower molecular weight plasma multimers, originally composed of intact 225-kDa subunits, by a metalloproteinase. Proteolysis generates two fragments of 140-and 176-kDa, which originate from cleavage of peptide bond Tyr842-Met843 and which represent vWF residues 1-842 and 843-2050, respectively; a very small amount of 189-kDa fragment can also be found in normal plasma. We describe here a two-dimensional (2-D) method to analyze plasma vWF structure.  相似文献   
70.
BACKGROUND: Patients with non-ulcer dyspepsia (NUD) responding to treatment with H2-receptor antagonists have no clinically useful characteristics. This trial compares the gastro-oesophageal reflux pattern as measured by 24-h oesophageal pH monitoring in patients responding to ranitidine with that of non-responders. METHODS: Thirty-one patients with NUD were randomized to 6 weeks' double-blind alternating treatment with 150 mg ranitidine twice daily or placebo and classified as responders or non-responders. RESULTS: Pathologic gastro-oesophageal reflux was seen in 3 of the 13 responders and 4 of the 18 no-responders (NS). The responders had frequent short reflux episodes (< 1 min in duration). When 4 patients with > or = 5 reflux episodes longer than 5 min were excluded, the number of short reflux episodes (median) in responders and non-responders was 32 and 14, respectively. The difference is statistically significant (p = 0.025). There were no other differences between the groups. CONCLUSIONS: In this study patients with NUD responding to ranitidine were characterized by frequent short reflux episodes in the absence of numerous long reflux episodes.  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