全文获取类型
收费全文 | 3025篇 |
免费 | 2篇 |
专业分类
综合类 | 3篇 |
化学工业 | 9篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
轻工业 | 1篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 1篇 |
一般工业技术 | 6篇 |
冶金工业 | 2994篇 |
自动化技术 | 7篇 |
出版年
2024年 | 1篇 |
2021年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 4篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 88篇 |
1998年 | 885篇 |
1997年 | 492篇 |
1996年 | 314篇 |
1995年 | 169篇 |
1994年 | 148篇 |
1993年 | 171篇 |
1992年 | 25篇 |
1991年 | 36篇 |
1990年 | 38篇 |
1989年 | 45篇 |
1988年 | 53篇 |
1987年 | 54篇 |
1986年 | 36篇 |
1985年 | 33篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 20篇 |
1980年 | 38篇 |
1979年 | 6篇 |
1978年 | 12篇 |
1977年 | 93篇 |
1976年 | 215篇 |
1975年 | 6篇 |
1955年 | 1篇 |
排序方式: 共有3027条查询结果,搜索用时 0 毫秒
61.
62.
63.
HJ Aubin C Laureaux F Zerah S Tilikete F Vernier B Vallat D Barrucand 《Canadian Metallurgical Quarterly》1998,44(7):638-643
BACKGROUND: Recent reports suggest that gamma-glutamyl transferase (GGT) decreases with coffee intake. The aim of this study was to examine the joint influence of alcohol, tobacco, cotinine, coffee, and caffeine on biological markers of heavy drinking in an alcoholic population. METHODS: Subjects were 160 alcohol-dependent inpatients. Biological assessments, performed at admission, were plasma levels of GGT, apolipoprotein AI, aspartate aminotransferase, and mean corpuscular volume (MCV), and urine cotinine and caffeine indexes. Years of alcohol abuse and of smoking, alcohol and coffee intake, and smoking rate were estimated in a semistructured interview, and Fagerstr?m Tolerance Questionnaire was completed by inpatients. RESULTS: Coffee intake, but not caffeine, correlated negatively with biological markers of heavy drinking, after controlling for alcohol and tobacco intake. Years of smoking correlated positively to MCV, after controlling for alcohol and coffee intake. CONCLUSIONS: Concerning the effect of coffee, the most likely hypothesis is that noncaffeine coffee fractions have a protective effect on liver cells. Concerning the effect of smoking, one can propose that the increase of MCV with smoking could be a consequence of carbon monoxide inhalation, leading to hypoxemia, or of folate deficiency. 相似文献
64.
65.
66.
67.
68.
We report the results of a comprehensive search of Drosophila melanogaster DNA sequences in GenBank for di-, tri-, and tetranucleotide repeats of more than four repeat units, and a DNA library screen for dinucleotide repeats. Dinucleotide repeats are more abundant (66%) than tri- (30%) or tetranucleotide (4%) repeats. We estimate that 1917 dinucleotide repeats with 10 or more repeat units are present in the euchromatic D. melanogaster genome and, on average, they occur once every 60 kb. Relative to many other animals, dinucleotide repeats in D. melanogaster are short. Tri- and tetranucleotide repeats have even fewer repeat units on average than dinucleotide repeats. Our WorldWide Web site (http://www.bio.cornell.edu/genetics/aquadro/+ ++aquadro.html) posts the complete list of 1298 microsatellites (> or = five repeat units) identified from the GenBank search. We also summarize assay conditions for 70 D. melanogaster microsatellites characterized in previous studies and an additional 56 newly characterized markers. 相似文献
69.
JM Koelman HJ Noteborn de Goey LP BJ Verhaar JT Walraven 《Canadian Metallurgical Quarterly》1985,32(11):7195-7198
70.