全文获取类型
收费全文 | 1920篇 |
免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 29篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 6篇 |
轻工业 | 37篇 |
水利工程 | 2篇 |
无线电 | 8篇 |
一般工业技术 | 24篇 |
冶金工业 | 1792篇 |
自动化技术 | 8篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 49篇 |
1998年 | 604篇 |
1997年 | 328篇 |
1996年 | 209篇 |
1995年 | 128篇 |
1994年 | 80篇 |
1993年 | 102篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 9篇 |
1985年 | 20篇 |
1983年 | 3篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1977年 | 51篇 |
1976年 | 92篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1922条查询结果,搜索用时 171 毫秒
121.
SP Alsemgeest GA van ''t Klooster AS van Miert CK Hulskamp-Koch E Gruys 《Canadian Metallurgical Quarterly》1996,53(1-2):179-184
OBJECTIVE: To determine placental transfer of ketanserin and to assess the effect of serotonin-2 receptor blockade by ketanserin on serotonin- and phenylephrine-induced vasoconstriction. STUDY DESIGN: Five chronically instrumented pregnant ewes at 120 days gestation were injected with 20 mg ketanserin i.v., and fetal and maternal arterial samples were obtained at predetermined intervals to assess placental transfer. Maternal and fetal responses of blood flows and pressures were determined after injected of serotonin (20 micrograms/kg) or phenylephrine (10 micrograms/kg) before and after ketanserin (0.75 mg/kg). RESULTS: In the ewe, ketanserin is transferred across the placenta and reaches measurable levels in the fetal lamb. Ketanserin blocks the maternal and fetal serotonin-induced rise in arterial pressure, but not the serotonin-induced reduction in uterine blood flow. CONCLUSION: In the pregnant ewe, the serotonin-induced rise in maternal and fetal blood pressure is effectively antagonized by ketanserin, whereas the serotonin-induced reduction in uterine blood flow is not. 相似文献
122.
SP Goldman 《Canadian Metallurgical Quarterly》1995,52(5):3718-3729
123.
124.
125.
126.
The folic acid antagonists, methotrexate and aminopterin, are known to be teratogenic in humans. The critical period for their teratogenecity is suspected to be between 6 to 8 weeks post-conception. Fetal exposure from 10 to 32 weeks weeks post-conception to methotrexate alone or in combination with other anti-cancer drugs has not resulted in obvious teratogenic effects. Methotrexate is often used to treat cancers but is occasionally used as an abortifacient. The long-term outcome of the fetal aminopterin syndrome has been published in only four adults. We report on a 28-year-old man with fetal methotrexate syndrome and two children with mild manifestations of the syndrome. One child was inadvertently exposed to methotrexate from 7 1/2 through 30 weeks post-conception because his mother was receiving it for treatment of breast cancer. The other was exposed from 11 weeks and 5 days through 25 weeks in an attempt to induce abortion. The 28-year-old man has craniofacial and digital anomalies, growth retardation but normal intelligence as noted in the previously reported cases. These cases remind us of the teratogenicity of methotrexate and should serve as a warning that if methotrexate is used as an abortifaciant and an abortion does not ensue, there is a teratogenic risk. 相似文献
127.
MB Wang N Kuber MM Kerner SP Lee GF Juilliard E Abemayor 《Canadian Metallurgical Quarterly》1998,27(5):263-269
A diffusion cell with an artificial membrane and the single-pass perfused rabbit ear were used to evaluate the percutaneous absorption of clonazepam from various 2-hydroxyethyl acetate (HEA) patches. The influence on drug permeation of the various type of enhancers (isopropylmyristate, lauryl alcohol, propylene glycol and water) in the patches was tested. A comparison between the two types of systems of percutaneous absorption of clonazepam has been done. The results showed that HEA patches produce controlled uniform drug release, modulated by the addition of enhancers. 相似文献
128.
129.
The liver S9 head space vial equilibration technique is an in vitro alternative that holds promises for a satisfactory in vivo extrapolation of liver metabolism of volatile organic chemicals. The aim of this study was to investigate the suitability of this methodology for the extrapolation of in vitro metabolic data from rodent to man by allometry with the two highly metabolized organic solvents toluene and n-hexane as model substances. The calculated hepatic clearance of toluene in man from rodent liver S9 in this study was equal to the reported total body clearance of toluene in man, suggesting insignificant extrahepatic clearance of toluene in humans. The calculated hepatic clearance of n-hexane was less than the reported values of total body clearance of n-hexane in man, indicating an about 80% extrahepatic clearance of n-hexane in humans. Both results are in line with our present knowledge of the metabolism of the two organic solvents in man. Allometric scaling from rodent liver S9 head space incubations to in vivo metabolism of toluene and n-hexane in man thus seems promising and could be a method of choice for scaling of organic solvent metabolism in general. 相似文献
130.
Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States 总被引:3,自引:0,他引:3
RC Lawrence CG Helmick FC Arnett RA Deyo DT Felson EH Giannini SP Heyse R Hirsch MC Hochberg GG Hunder MH Liang SR Pillemer VD Steen F Wolfe 《Canadian Metallurgical Quarterly》1998,41(5):778-799
OBJECTIVE: To provide a single source for the best available estimates of the national prevalence of arthritis in general and of selected musculoskeletal disorders (osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, the spondylarthropathies, systemic lupus erythematosus, scleroderma, polymyalgia rheumatica/giant cell arteritis, gout, fibromyalgia, and low back pain). METHODS: The National Arthritis Data Workgroup reviewed data from available surveys, such as the National Health and Nutrition Examination Survey series. For overall national estimates, we used surveys based on representative samples. Because data based on national population samples are unavailable for most specific musculoskeletal conditions, we derived data from various smaller survey samples from defined populations. Prevalence estimates from these surveys were linked to 1990 US Bureau of the Census population data to calculate national estimates. We also estimated the expected frequency of arthritis in the year 2020. RESULTS: Current national estimates are provided, with important caveats regarding their interpretation, for self-reported arthritis and selected conditions. An estimated 15% (40 million) of Americans had some form of arthritis in 1995. By the year 2020, an estimated 18.2% (59.4 million) will be affected. CONCLUSION: Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population. 相似文献