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   710篇
  免费   4篇
电工技术   2篇
综合类   2篇
化学工业   30篇
金属工艺   1篇
机械仪表   8篇
建筑科学   15篇
矿业工程   1篇
能源动力   5篇
轻工业   17篇
水利工程   1篇
石油天然气   2篇
无线电   14篇
一般工业技术   58篇
冶金工业   548篇
原子能技术   2篇
自动化技术   8篇
  2020年   4篇
  2019年   4篇
  2017年   7篇
  2016年   2篇
  2014年   4篇
  2013年   7篇
  2012年   8篇
  2011年   14篇
  2009年   6篇
  2008年   11篇
  2007年   7篇
  2006年   8篇
  2005年   4篇
  2004年   3篇
  2003年   4篇
  2002年   4篇
  2001年   6篇
  2000年   1篇
  1999年   25篇
  1998年   162篇
  1997年   92篇
  1996年   73篇
  1995年   37篇
  1994年   32篇
  1993年   30篇
  1992年   6篇
  1991年   5篇
  1990年   5篇
  1989年   3篇
  1988年   7篇
  1987年   9篇
  1986年   5篇
  1985年   11篇
  1984年   1篇
  1983年   2篇
  1982年   3篇
  1981年   7篇
  1980年   6篇
  1978年   5篇
  1977年   16篇
  1976年   46篇
  1975年   5篇
  1973年   2篇
  1971年   2篇
  1967年   1篇
  1966年   1篇
  1965年   1篇
  1960年   1篇
  1957年   1篇
  1956年   4篇
排序方式: 共有714条查询结果,搜索用时 11 毫秒
11.
12.
13.
In mid-summer 1997, just as the United States National Cancer Institute was acknowledging that the nuclear bomb tests at the Nevada Test Site may ultimately cause up to 75,000 cases of thyroid cancer in people who were living in the USA in the 1950s and 1960s, the Australian authorities were mooting the possibility that the Maralinga test sites in South Australia should become a tourist attraction. Some Aboriginal tribal leaders welcomed this proposed use when the 20 million Pounds 'clean-up' being paid for by the United Kingdom government as some compensation for using the area for its weapons tests in the 1950s and 1960s is completed. This paper surveys the attempts to clean up the site of UK nuclear weapons tests in the 1950s, not least by attempting to vitrify vast tracts of desert.  相似文献   
14.
15.
H.J.M. Hanley 《低温学》1976,16(11):643-651
A corresponding states procedure to predict the viscosity and thermal conductivity coefficients of a pure fluid or mixture is discussed. We show the transport properties of a fluid or mixture can be calculated to within experimental error given only corresponding values for a reference fluid and equation of state data. With methane, as the reference fluid, we consider nitrogen, ethane, propane, butane, carbon dioxide, and mixtures of these fluids. LNG is also included. It is shown that the conventional corresponding states approach is not sufficient to predict correctly the transport properties. The effect of internal degrees of freedom on the thermal conductivity coefficient and the enhancement in the critical region for this coefficient is discussed briefly.  相似文献   
16.
17.
One hundred and fifty lungs from the cases below 15 years of age with various congenital heart diseases and 80 controls were used for histometrical and histological studies. Cases with congenital heart disease were divided into two groups of the increased and the decreased pulmonary blood flow. In the former group, the thickness of the pulmonary arterial media was the same as that of controls in the neonatal period, and through the wall thickness gradually decreased in a pattern seen in controls, the thickness was constantly larger than that of controls. In some cases, the media increased gradually within 6 months after birth. Pneumonia and massive pulmonary hemorrhage were seen in a higher incidence in autopsy cases. Pneumonia in younger infants was histologically characteristic and possibly more correlated to their death. In the latter group, most of the cases were with the thinner medias of the pulmonary arteries. Massive pulmonary hemorrhage was not common in the latter group.  相似文献   
18.
19.
The ST-16 antigenic specificity of the HLA-B locus is defined as a B39 variant of Mexican-Americans. Nucleotide sequencing of cDNA shows the ST-16 allele (B*3905) differs from B*39011 by a single substitution that substitutes tyrosine for aspartic acid at position 74 of the mature class I heavy chain. The complete coding region sequence for the common caucasoid allele encoding the B38 antigen has been determined. This B*3801 allele differs from B*3802 at two nucleotide substitutions within the Bw4 sequence motif. B*3801 and B*3802 may have been derived independently from B*39011 by conversion events with B alleles donating distinctive Bw4 motifs. A novel allele B*39022 derived from a Colombian Indian differs from the B*39021 allele of Japanese origin at two widely separated silent substitutions. Comparison of sequences for the known B16 alleles suggest that B*39021 and B*39022 were independently derived by recombination from B*39013 and B*39011 respectively.  相似文献   
20.
Circulating fatty acids (FA) derived largely from dairy consumption have most commonly been measured in total human serum or phospholipid (PL) fractions, and have been used as validated biomarkers of dairy intake in a growing number of epidemiological studies. Nevertheless, measurement and characterization of a wider spectrum of FA biomarkers of dairy across the four major serum lipid fractions is lacking. This study aimed to (1) quantify FA biomarkers of dairy in PL, triacylglycerol (TAG), cholesteryl ester (CE), and unesterified fatty acid (FFA) serum lipid fractions; and (2) identify potential demographic and metabolic factors that may modify the proportions of these FA across serum fractions. Baseline data from 444 adults in the PROMISE cohort were analyzed. FA biomarkers, 15:0, t16:1n-7, 18:2-c9,t11, and t18:1n-7 were quantified from serum. Dairy intake was estimated using the validated Canadian Diet History Questionnaire. Our results show that t18:1n-7 was the most abundant FA biomarker in all fractions except CE, where 18:2-c9,t11 was the most abundant. Positive correlations within fractions, and across FA in the PL, CE, and FFA fractions were found, however, TAG FA were negatively correlated with the other fractions. PL and CE FA were positively associated with dairy intake, and negatively associated with markers of dysmetabolism while, in contrast, these markers were predictors of higher TAG dairy FA. This study is the first to demonstrate distinct proportions of dairy FA in different serum lipid fractions. PL and CE FA marked dairy intake in this cohort, while TAG FA appeared to be markers of dysmetabolism.  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