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   3205篇
  免费   7篇
  国内免费   1篇
电工技术   4篇
综合类   1篇
化学工业   183篇
金属工艺   6篇
机械仪表   14篇
建筑科学   17篇
矿业工程   2篇
能源动力   5篇
轻工业   28篇
水利工程   2篇
石油天然气   1篇
武器工业   1篇
无线电   47篇
一般工业技术   69篇
冶金工业   2773篇
原子能技术   6篇
自动化技术   54篇
  2017年   6篇
  2014年   8篇
  2013年   8篇
  2011年   9篇
  2010年   13篇
  2009年   14篇
  2008年   17篇
  2007年   9篇
  2006年   11篇
  2005年   16篇
  2004年   22篇
  2003年   13篇
  2002年   17篇
  2001年   9篇
  2000年   10篇
  1999年   93篇
  1998年   839篇
  1997年   489篇
  1996年   305篇
  1995年   167篇
  1994年   148篇
  1993年   164篇
  1992年   33篇
  1991年   39篇
  1990年   35篇
  1989年   45篇
  1988年   44篇
  1987年   37篇
  1986年   29篇
  1985年   36篇
  1984年   7篇
  1983年   9篇
  1982年   21篇
  1981年   16篇
  1980年   22篇
  1979年   17篇
  1978年   10篇
  1977年   64篇
  1976年   192篇
  1973年   11篇
  1972年   6篇
  1971年   9篇
  1969年   6篇
  1968年   6篇
  1966年   7篇
  1965年   14篇
  1963年   8篇
  1962年   9篇
  1961年   9篇
  1958年   7篇
排序方式: 共有3213条查询结果,搜索用时 15 毫秒
991.
Total replacement of the elbow joint has been performed on 86 elbows at the Mayo Clinic, all but 15 in patients with rheumatoid arthritis. The Mayo design, which replaces both radiohumeral and humeroulnar joints, was used in 41 elbows, almost all in rheumatoid patients, with 71% good results. The Coonrad hinge with polyethylene bushings was used in 34 elbows; it was successful in 64% of rheumatoid patients, but failed in 46% of posttraumatic patients with bone loss. Previous designs have failed because of humeral loosening. Total elbow replacement is a technique still to be perfected in medical centers before general release.  相似文献   
992.
As a rule, in equaliser training algorithms complexity increases with efficiency. Unfortunately, complex recursive algorithms do not suit high-bandwidth systems. This letter describes a nonrecursive technique for the derivation of the weight vector in an optimally variable length transversal equaliser.  相似文献   
993.
Topical application of povidone iodine on the umbilical cord and normal intact skin of newborn infants resulted in significantly elevated plasma iodine levels. High iodine levels were also found in two neonates who had povidone iodine applied to denuded skin. No significant alteration in thyroid function was seen. The possible toxic manifestations of high plasma iodine levels are discussed.  相似文献   
994.
Previously (Liu et al, Cancer Res., 56: 3371-3379, 1996), we isolated a novel serine protease-like gene--Normal Epithelial Cell Specific-1 (NES1)--that is expressed in normal mammary epithelial cells but is down-regulated in most breast cancer cell lines. Here, we demonstrate that stable expression of NES1 in the NES1-negative MDA-MB-231 breast cancer cell line suppressed the oncogenicity as revealed by inhibition of the anchorage-independent growth and tumor formation in nude mice. Fluorescence in situ hybridization localized the NES1 gene to chromosome 19q13.3, a region that contains genes for related proteases (including the prostate-specific antigen) and is rearranged in human cancers. Similar to breast cancer cell lines, prostate cancer cell lines also lacked NES1 mRNA and protein expression. Together, these results strongly suggest a tumor-suppressor role for NES1 in breast and prostate cancer.  相似文献   
995.
Production of vegetable, animal and marine oils containing more than about 40% unsaturated fatty acids totaled 15,000 million pounds in 1968, almost on the scale of petrochemical production. The greater share (64%) of this nonfossil oil production was directed toward food uses, the remainder toward industrial and animal feed uses. The variety of chemical reactions carried out on these unsaturated fatty acid products include hydrogenation, interesterification, dimerization, sulfation, formation of nitrogen compounds, epoxidation, alkaline cleavage and oxidative ozonolysis. Some of these reactions have been developed at Utilization Research and Development Divisions of the Agricultural Research Service, U.S. Department of Agriculture. Research is continuing in developing new reactions for potential industrial application. An example is reductive ozonolysis of unsaturated fatty esters to produce monofunctional aldehydes and bifunctional aldehyde esters. Presented at the ISF-AOCS World Congress, Chicago, September 1970. No. Market. Nutr. Res. Div., ARS, USDA.  相似文献   
996.
A new pyrimidine nucleoside, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil, previously has been shown to be active against the herpes group of viruses in vitro and in vivo. It is also active against mouse and human leukemic cells in culture and against mouse leukemias L1210, P388, and P815 in vivo. In contrast to other 1-beta-D-arabinofuranosylcytosine (ara-C) derivatives, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil, when given either i.p. or p.o., is highly active against lines of leukemias P815 and L1210 made resistant to ara-C. Against P815/ara-C and L1210/araC, it is more effective than is 5-azacytidine, a drug which has shown definite effectiveness in patients with acute leukemia whose disease has become resistant to ara-C. For these reasons, 2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil would seem to merit clinical trial in patients with acute nonlymphocytic leukemia whose disease has become resistant to ara-C.  相似文献   
997.
998.
999.
The YopM virulence protein of Yersinia pestis has been described as binding human alpha-thrombin and inhibiting thrombin-induced platelet aggregation in vitro. However, recent studies have shown that a YopM-CyaA fusion protein could be targeted vectorially into eukaryotic cells through the Yersinia type III secretion system. In this study, our objective was to characterize YopM's fate in more detail. We followed YopM in the culture medium and inside infected HeLa cells. We confirmed that the native YopM is targeted into HeLa cells, where it is insensitive to exogenous trypsin. The bacteria must be surface located to target YopM, and YopB and YopD are necessary, whereas the LcrE protein (called also YopN) makes this process more efficient. Immunofluorescence localization revealed that YopM, in contrast to YopE, is not only targeted to the cytoplasm but also trafficks to the cell's nucleus by means of a vesicle-associated pathway that is strongly inhibited by brefeldin A, perturbed by monensin or bafilomycin A1 and dependent upon microtubules (decreased by colchicine and nocodazole). These findings revealed a novel interaction of Yersinia pestis with its eukaryotic host.  相似文献   
1000.
Familial CRST syndrome with sicca complex   总被引:2,自引:0,他引:2  
As a result of critical review of information on lipid composition of foods, representative values have been derived for the lipid and fatty acid contents of lamb and veal. Comprehensive tabulations of fatty acids in 100-gm. portions of raw and cooked retail cuts are given. The mean fatty acid profiles of the lean and adipose tissues which were used for computing the fatty acid values in the food tables are presented. The lean tissue lipid of lamb contains a significant amount of caprylic, arachidic, and arachidonic acids which are not present in the adipose tissue. A comparison of beef and veal shows that veal lipid is a richer source of polyunsaturated fatty acids. The new values presented here for fatty acids in lamb and veal should provide nutritionists and dietitians better means for evaluating diets.  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