全文获取类型
收费全文 | 2377篇 |
免费 | 1篇 |
专业分类
化学工业 | 36篇 |
机械仪表 | 3篇 |
建筑科学 | 2篇 |
轻工业 | 13篇 |
石油天然气 | 1篇 |
无线电 | 4篇 |
一般工业技术 | 13篇 |
冶金工业 | 2296篇 |
自动化技术 | 10篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 57篇 |
1998年 | 706篇 |
1997年 | 394篇 |
1996年 | 270篇 |
1995年 | 139篇 |
1994年 | 132篇 |
1993年 | 122篇 |
1992年 | 17篇 |
1991年 | 27篇 |
1990年 | 25篇 |
1989年 | 41篇 |
1988年 | 37篇 |
1987年 | 24篇 |
1986年 | 27篇 |
1985年 | 29篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 1篇 |
1978年 | 6篇 |
1977年 | 67篇 |
1976年 | 143篇 |
1975年 | 6篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有2378条查询结果,搜索用时 0 毫秒
1.
2.
3.
KL Gatford TP Fletcher IJ Clarke PC Owens KJ Quinn PE Walton PA Grant BJ Hosking AR Egan EN Ponnampalam 《Canadian Metallurgical Quarterly》1996,74(6):1314-1325
The effects of sex and age on patterns of circulating somatotropin (ST) concentration and plasma IGF-I, IGF-II, insulin, and IGF binding protein-3 (IGFBP-3) were studied in ram, wether, and ewe lambs (n = 7 or 8) sampled at mean ages of 81 (I1) and 158 d (I2). Between 81 and 158 d of age, rams grew more rapidly than wethers (P < .01), and wethers grew more rapidly than ewes (P < .01). The sex differences in growth were reflected in empty body weight at slaughter: rams > wethers > ewes (P < .05). Mean plasma ST concentrations, ST pulse amplitude, and integrated plasma ST concentrations were greater (P < .05) in rams than in ewes at I1 and I2. Characteristics of the ST plasma profile in wethers were generally intermediate between those of rams and ewes. The interpulse interval was greater in ewes than in wethers at I2. The IGF-I and IGFBP-3 concentrations were greater in rams than in ewes at both sampling times. Plasma IGF-II was greater in ewes than in rams at I2. Mean plasma ST was approximately two thirds less at I2 than at I1 regardless of sex. Mean plasma ST and IGF-I at both ages were positively correlated with growth. Mean plasma ST at I2 was negatively correlated with fatness at slaughter. Sex and age significantly affected patterns of circulating ST and concentrations of IGF-I and IGFBP-3 in prepubertal growing lambs, under conditions for which growth rates and composition were also sexually dimorphic. 相似文献
4.
KS Min AR Khan MK Kwon YJ Jung Z Yun Y Kiso 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(8):909-915
The performance of a laboratory‐scale anaerobic acidogenic fermenter fed with a mixture of blended kitchen food‐waste and primary sludge from a sewage treatment plant was investigated for the production of volatile fatty acids (VFA). The operating variables for acidogenic fermentation were kitchen food‐waste content (10 and 25 wt %), hydraulic retention time (HRT: 1, 3 and 5 days), temperature (ambient: 18 ± 2 °C, and mesophilic: 35 ± 2 °C) and pH (varied from 5.2 to 6.7). The experimental results indicated that effluent VFA concentrations and VFA production rates were higher at ambient temperature than at mesophilic conditions. The net amount of VFA with 10 wt % food‐waste increased up to 920 mg dm?3 with an increase of HRT, but contrasting results (a decrease of 2610 mg dm?3) were found due to the conversion of VFA into biogas in the case of 25 wt % food‐waste, which increased significantly at HRT of 3–5 days. In terms of biogas composition (CO2 and CH4), the organic matter was converted into CO2 through the oxidative pathway by facultative species at low temperature while mesophilic temperature and optimum pH (6.3–7.8) played a pivotal role in increasing rate of conversion of VFA into biogas by methanogenesis. Rates of VFA production and their conversion are dependent on the food‐waste content in the mixture. Yet, the higher concentration of food‐waste (25% compared with 10%) did not produce VFA proportionally due to the increased rate of conversion of VFA into gaseous products. The maximum VFA production rate (0.318 g VFAproduced g?1 VSfed day?1) was achieved in the 10 wt % food‐waste at ambient temperature and at a 5‐day HRT. Copyright © 2005 Society of Chemical Industry 相似文献
5.
AR Hart B Jestico C Antill M Taylor JF Mayberry 《Canadian Metallurgical Quarterly》1996,110(4):247-249
We studied 100 healthy children looking for lactose malabsortion. We performed in all of them the lactose breath test. We found a 10% with lactose malabsortion. There was no correlation between lactose breath test and fecal reducing substances. 相似文献
6.
This article presents data from a population-based, random-digit dialing telephone survey of 1228 employed adults in Washington State, conducted 1989 through 1990. Eighty-one percent of men and 91% of women reported work-site smoking restrictions. Employees in work sites with no-smoking policies were less likely to be current smokers; men in work sites with policies restricting smoking smoked fewer cigarettes on both workdays and nonworkdays. Forty-eight percent of male and 53% of female smokers reported reduced smoking as a result of work-site policy. Work-site smoking policies, intended to protect against smoke exposure, may also reduce employee smoking. 相似文献
7.
8.
9.
10.