全文获取类型
收费全文 | 1106篇 |
免费 | 8篇 |
专业分类
安全科学 | 20篇 |
废物处理 | 1篇 |
环保管理 | 111篇 |
综合类 | 797篇 |
基础理论 | 88篇 |
环境理论 | 1篇 |
污染及防治 | 56篇 |
评价与监测 | 24篇 |
社会与环境 | 11篇 |
灾害及防治 | 5篇 |
出版年
2021年 | 4篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 46篇 |
2012年 | 4篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 19篇 |
2002年 | 11篇 |
2000年 | 4篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1995年 | 56篇 |
1994年 | 53篇 |
1993年 | 40篇 |
1992年 | 33篇 |
1991年 | 27篇 |
1990年 | 33篇 |
1989年 | 26篇 |
1988年 | 36篇 |
1987年 | 32篇 |
1986年 | 22篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1979年 | 6篇 |
1976年 | 6篇 |
1975年 | 10篇 |
1974年 | 4篇 |
1973年 | 10篇 |
1971年 | 5篇 |
1961年 | 3篇 |
1919年 | 47篇 |
1918年 | 44篇 |
1917年 | 36篇 |
1916年 | 53篇 |
1915年 | 37篇 |
1914年 | 71篇 |
1913年 | 106篇 |
排序方式: 共有1114条查询结果,搜索用时 15 毫秒
581.
582.
Privatdozent Dr. Ernst G. Pringsheim 《Die Naturwissenschaften》1913,1(21):495-497
583.
584.
585.
586.
587.
An improved method is described for the study of heterotrophic utilization of dissolved organic substances by marine microorganisms. The method is based on the use of 3H-labelled organic substrates of very high specific activity, rather than the conventionally used 14C-labelled substrates. Direct measurement of the rate of tracer uptake at near ambient concentration can thus be made instead of extrapolation using the Michaelis-Menten equation. The method also permits comparison between the rates of tracer uptake in sub-samples exposed to different physico-chemical conditions (temperature, light, pollutants, etc.) without the necessity of determining the ambient substrate concentration. The method was applied to the determination of D-glucose uptake by nearshore and pelagic natural microbial populations, and was found to be sensitive and convenient. 相似文献
588.
Bruce E. Lyon Robert D. Montgomerie Linda D. Hamilton 《Behavioral ecology and sociobiology》1987,20(5):377-382
Summary We experimentally removed males from a random sample of 14 snow bunting (Plectrophenax nivalis) pairs to determine the influence of male parental care on reproductive success. Widowed females increased their rate of food delivery to nestlings by increasing their feeding visit rate but not their load size. However, Widows were only able to achieve 73% of the food delivery rate of Control pairs and, as a result, they raised fewer offspring of lower quality (i.e. lower mass at fledging). Total brood mass raised by Widows was only 55% of that of Control pairs. Thus, in the year of our experiment, male parental care in the nestling period almost doubled the reproductive success realized from a brood. Our experiment, however, was done in a year of poor food availability and data from the previous year, when food supply was higher, indicate that males may not always be so important. Since nestling food supply appears to be unpredictable at the time of pair formation, we suggest that monogamy is a bet-hedging strategy in case of poor food availability. As a consequence the importance of male parental care in some years may explain why snow buntings are almost always monogamous. 相似文献
589.
Summary Increasingly stringent environmental lesislation and a growing consciousness of environmental issues within the community are spurring companies into adopting environmental improvement programmes. Enhanced environmental management not only ensures compliance with legislation but has other benefits, including reduced energy and waste disposal costs, improved public image, acess to green markets and lower insurance premiums. BS7750 and the Eco-Management and Audit Scheme now offer businesses the opportunity to establish a systematic and accredited environmental management system which will serve as a yardstick of environmental quality. 相似文献
590.