全文获取类型
收费全文 | 835篇 |
免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 17篇 |
金属工艺 | 6篇 |
机械仪表 | 3篇 |
建筑科学 | 6篇 |
能源动力 | 2篇 |
轻工业 | 18篇 |
水利工程 | 1篇 |
无线电 | 13篇 |
一般工业技术 | 16篇 |
冶金工业 | 741篇 |
原子能技术 | 3篇 |
自动化技术 | 10篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2000年 | 4篇 |
1999年 | 17篇 |
1998年 | 210篇 |
1997年 | 125篇 |
1996年 | 79篇 |
1995年 | 49篇 |
1994年 | 53篇 |
1993年 | 40篇 |
1992年 | 7篇 |
1991年 | 16篇 |
1990年 | 10篇 |
1989年 | 22篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 19篇 |
1976年 | 38篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有837条查询结果,搜索用时 15 毫秒
51.
M Wartmann N Cella P Hofer B Groner X Liu L Hennighausen NE Hynes 《Canadian Metallurgical Quarterly》1996,271(50):31863-31868
52.
A mixture of D- and L-leucine N-Carboxyanhydride (NCA) having an enantiomeric composition of 65.6% L- and 34.4% D-isomer (i.e. 31.2% enantiomeric excess (e.e)) was polymerized to the extent of 52% with sodium methoxide initiator to yield a polyleucine product the enantiomeric composition of which was 72.7% L- and 27.3% D-leucine (45.4% e.e.). This polymer was in turn partially hydrolyzed by acid, whereupon the unhydrolyzed polyleucine residue was found to have an enantiomeric composition of 77.5% L- and 22.5% D-leucine (55.0% e.e.). Thus the e.e. increase in the partial polymerization step (14.2%) and the partial hydrolysis step (9.6%) combined to total 23.8% for the overall polymerization-hydrolysis sequence. On the basis of these model experiments it is proposed that repetitive partial polymerization hydrolysis reactions, driven by environmental dry-wet cycles, might have been operative on the primitive Earth to engender the abiotic evolution of optically enriched polypeptides. 相似文献
53.
54.
55.
56.
57.
58.
59.
JA Crozier VG Allen NE Jack JP Fontenot MA Cochran 《Canadian Metallurgical Quarterly》1997,75(6):1651-1658
Alfalfa (Medicago sativa L.), low-endophyte (< 5%) tall fescue (Festuca arundinacea Schreb.), and caucasian bluestem (Bothriochloa caucasica [Trin.] C.E. Hubbard) were fed as chopped hay to six Arabian geldings (BW 441 kg; SE 2) in intake and digestibility experiments to determine nutritional value for horses at maintenance. Each experimental design was a replicated Latin square. Alfalfa was higher in DM and CP digestibility, IVDMD, apparent absorption of Ca, K, and S, and voluntary intake than the grasses (P < .05). Caucasian bluestem was higher in Zn but was lower in CP, TNC, Mg, P, K, S, and Cu concentrations than tall fescue. Crude protein digestibility and apparent absorption of Mg, K, and S were higher (P < .05) for tall fescue than for caucasian bluestem. Geldings fed alfalfa for ad libitum intake had higher serum concentrations of vitamin A, blood urea nitrogen, P, S, and Cu than geldings fed grass hays. Serum Zn was higher (P < .05), whole blood Se tended to be higher (P < .06), and BUN was lower (P < .05) in geldings fed caucasian bluestem than in those fed tall fescue. All forages met requirements for CP, Ca, Mg, K, and Fe when fed for ad libitum intake but were deficient in Cu for horses at maintenance. Caucasian bluestem was borderline in CP and was deficient in P but was the only forage that met the Zn requirement for the horses. Based on these results, caucasian bluestem could be a useful hay for horses but may require supplementation of CP and P. 相似文献
60.
NE Mishchuk 《Canadian Metallurgical Quarterly》1997,(5):71-74
Diastolic function was studied of left ventricle by pulse Doppler echocardiography in 42 patients with type I diabetes mellitus (DM) and 46 essentially healthy individuals. In DM patients diastolic function was manifested by rise in peak velocity of atrial filling, decrease in ratio of peak velocity of early filling to that of late one, increase in left ventricular end-diastolic pressure. The findings available suggest the atrial phase has an important part in the structure of diastole in DM patients because of a combined influence of tachycardia and increased rigidity of left ventricular myocardium. Values for early filling in the patients did not differ from those in controls. A conclusion is drawn to the effect that in DM patients tachycardia and hypercatecholaminemia may partly mask disturbances in relaxation. 相似文献