全文获取类型
收费全文 | 1851篇 |
免费 | 0篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 44篇 |
建筑科学 | 2篇 |
轻工业 | 8篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 1785篇 |
自动化技术 | 4篇 |
出版年
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2006年 | 1篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 53篇 |
1998年 | 548篇 |
1997年 | 345篇 |
1996年 | 217篇 |
1995年 | 94篇 |
1994年 | 98篇 |
1993年 | 117篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 1篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 2篇 |
1978年 | 10篇 |
1977年 | 33篇 |
1976年 | 86篇 |
1975年 | 3篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有1851条查询结果,搜索用时 906 毫秒
31.
32.
A filtration technique was employed to trap 14CO2 continuously for liquid scintillation counting. Devices for delivering scintillator and ethanolamine solutions were combined symmetrically with two fritted-glass aspirators for alternating operation. The collector was regulated by a fraction collector timer. Trial and animal tests indicated that the described method was efficient, reliable, and more convenient for frequent collection over long periods than alternative methods. The automatic collector was used for metabolic studies of [1-14C] arachidonic acid in rats kept in metabolic cages and the results were processed by multicompartmental analysis. 相似文献
33.
A high frequency of viral hepatitis has been reported after treatment with the human factor IX concentrate 'Konyne'. Clinical trials with 'Konyne' and a similar factor IX concentrate, called 'Preconativ', was started in Sweden 1969. During the first 2 years, 26 patients were treated with either one or both preparations. Nine patients developed viral hepatitis within 6 months after treatment. 'Preconativ' alone was introduced on the Swedish market in 1971. During the period 1971-1974, another 26 hemophiliacs were treated but only two cases of hepatitis have occurred. Selection of donors and screening for hepatitis B surface antigen in donor blood used for the manufacturing of 'Preconativ', might be contributing factors to this low hepatitis incidence. 相似文献
34.
35.
36.
37.
38.
39.
EY Adashi JA Rock D Guzick AC Wentz GS Jones HW Jones 《Canadian Metallurgical Quarterly》1981,36(3):320-325
Fertility following bilateral ovarian wedge resection (BOWR) was evaluated in a retrospective cohort study of 90 consecutive cases of the polycystic ovary syndrome. Post-BOWR follow-up was available for varying time spans of up to 10 years. BOWR resulted in the resumption of menstrual cyclicity in 91.1% (82/90) of the cases. However, within this ovulatory group, 26 patients were characterized by oligo-ovulation and a significantly reduced conception rate (29.2%), as compared with that of 56 normo-ovulatory counterparts (60.3%). Although the crude overall conception rate for this series was 47.8%, the overall cumulative probability of conception at the end of follow-up as determined by life table analysis was 73%. The likelihood of conception at any given point in time was estimated by a monthly fecundability rate of 1.34%. Our findings also indicate that the probability of post-BOWR conception was unaffected by age, race, ward status, or duration of infertility. In contrast, persistent post-BOWR oligo- or anovulation and the presence of concurrent tuboperitoneal disease were reaffirmed as the most important determinants of the likelihood of post-BOWR conception. A minimum incidence of 7.8% was documented for acquired post-BOWR pelvic disease. 相似文献
40.