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   557篇
  免费   2篇
电工技术   3篇
综合类   1篇
化学工业   20篇
金属工艺   2篇
机械仪表   1篇
建筑科学   1篇
轻工业   9篇
无线电   17篇
一般工业技术   26篇
冶金工业   468篇
原子能技术   3篇
自动化技术   8篇
  2022年   2篇
  2021年   4篇
  2019年   1篇
  2017年   4篇
  2016年   1篇
  2015年   2篇
  2013年   3篇
  2012年   4篇
  2011年   4篇
  2010年   5篇
  2009年   3篇
  2008年   5篇
  2007年   9篇
  2005年   3篇
  2004年   6篇
  2003年   3篇
  2002年   2篇
  2001年   1篇
  2000年   5篇
  1999年   19篇
  1998年   129篇
  1997年   84篇
  1996年   51篇
  1995年   30篇
  1994年   24篇
  1993年   27篇
  1992年   6篇
  1991年   11篇
  1990年   5篇
  1989年   8篇
  1988年   13篇
  1987年   6篇
  1986年   5篇
  1985年   9篇
  1983年   2篇
  1982年   2篇
  1981年   6篇
  1980年   8篇
  1979年   2篇
  1978年   3篇
  1977年   10篇
  1976年   26篇
  1975年   2篇
  1974年   1篇
  1967年   2篇
  1963年   1篇
排序方式: 共有559条查询结果,搜索用时 0 毫秒
101.
102.
An indirect enzyme-linked immunosorbent assay (ELISA) using natural disaccharide octyl bovine serum albumin (ND-O-BSA) as antigen was used in testing leprosy patients, contacts and a normal population in Cebu, The Philippines, from 1985 to 1989. A total of 1413 persons were studied. The results suggested that ELISA reactivity and the bacterial index (BI) correlate in a general way. In multibacillary (MB) leprosy, positivity ranges from 54.2% to 92.3% among patients with a BI of < 2+ to > 4+ on the Ridley scale, with an overall average of 84.5%. Paucibacillary (PB) leprosy patients have a low degree of reactivity, with only 15.0% ELISA positive. The test is more efficient in detecting MB than PB leprosy. The contacts of MB leprosy showed 6.5% positivity; contacts of PB leprosy, 7.0% positivity. The normal population showed 1.7% positive ELISA or 17 per thousand population, which is very much less than that of the household contacts. However, because the normal population is a much larger population than the household contact population in a community, more new leprosy cases would emanate from it. Leprosy workers are concerned about the transmission of the disease to household contacts. However, for the reason stated above, we should be more concerned with the silent spread of the disease to the normal population in the community.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
103.
Estramustine is an estradiol-based agent that has been shown to accumulate in human glioma cells, resulting in a concentration-dependent alteration in cell size and shape within minutes and an inhibition of proliferation over 3 to 6 days. We evaluated human glioblastoma cultures with [3H]thymidine incorporation assays to determine estramustine's early effects on deoxyribonucleic acid synthesis in these tumors. Because estramustine shares a common structural motif with other antimicrotubule drugs, we synthesized four A-ring conjugates of estrone that contained a carbamate moiety but lacked nitrogen mustard. These analogs were examined by [3H]thymidine incorporation and compared with vinblastine. Greater than 70% inhibition of [3H]thymidine incorporation occurred within 1 hour of treatment with estramustine at 10(-5) mol/L, which increased to 80% inhibition at 4 hours. Ethyl carbamate JE208 was nearly as effective as estramustine in inhibiting deoxyribonucleic acid synthesis, and both were more effective than vinblastine. The inhibitory effects of estramustine and estrone analogs were reversible; vinblastine was not reversible. Although estramustine and JE208 induced similar antiproliferative and morphological changes in glioblastoma cells that persisted for at least 4 days, there was a modest recovery of morphology and thymidine incorporation with JE208 after prolonged treatment. The common findings with estramustine and JE208 suggest that these agents may have a similar mechanism of action and form the basis for the investigation of new agents that may rapidly and reversibly inhibit glioblastoma.  相似文献   
104.
105.
106.
We have identified the human papillomavirus (HPV) DNA replication initiation protein E1 as a tight-binding substrate of cyclin E/cyclin-dependent kinase (Cdk) complexes by using expression cloning. E1, a DNA helicase, collaborates with the HPV E2 protein in ori-dependent replication. E1 formed complexes with cyclin E in insect and mammalian cells, independent of Cdks and E2. Additional cyclins, including A-, B-, and F-type (but not D-type), interacted with the E1/E2 complex, and A- and E-type cyclin kinases were capable of phosphorylating E1 and E2 in vitro. Association with cyclins and efficient phosphorylation of E1 required the presence of a cyclin interaction motif (the RXL motif). E1 lacking the RXL motif displayed defects in E2-dependent HPV ori replication in vivo. Consistent with a role for Cdk-mediated phosphorylation in E1 function, an E1 protein lacking all four candidate Cdk phosphorylation sites still associated with E2 and cyclin E but was impaired in HPV replication in vitro and in vivo. Our data reveal a link between cyclin/Cdk function and activation of HPV DNA replication through targeting of Cdk complexes to the E1 replication-initiation protein and suggest a functional role for E1 phosphorylation by Cdks. The use of cyclin-binding RXL motifs is now emerging as a major mechanism by which cyclins are targeted to key substrates.  相似文献   
107.
Twelve neurologically normal infants (age 2.9+/-0.9 months) with peptic esophagitis (grade 2) who did not respond to cimetidine (in addition to positioning, cisapride, and Gaviscon) were treated with omeprazole, 0.5 mg/kg once a day, for 6 weeks. The effectiveness of omeprazole was evaluated in all infants by clinical assessment and endoscopy before and after treatment and by 24-hour gastric pH monitoring during treatment in seven infants. Omeprazole therapy led to a marked decrease in symptoms, endoscopic and histologic signs of esophagitis, and intragastric acidity.  相似文献   
108.
The study was concerned with immune response in the workers engaged in rubber manufacture which is a cancer hazard. A group of healthy donors were in control. The study group was divided into those free from carcinogen-protein adducts (CPA) and those who revealed them and, therefore, are considered at high risk for cancer. CPAs containing benzidine, 2-naphtylamine or 3-oxyanthranyl acid were assayed in blood serum. B- and T-immunity inhibition was shown to be present in both study sub-groups. A significant difference in immune response indices was established between the CPA-free and CPA-containing groups of the rubber workers. The latter group had relatively higher levels of IgA, IgM and globulins of immunocomplexes, and revealed inhibition of formation of antibody-forming cells to ovine erythrocytes following injection of CPA-containing blood serum into mice as well as relatively higher suppression of T-cell immunity in the workers at high risk.  相似文献   
109.
110.
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