全文获取类型
收费全文 | 29631篇 |
免费 | 325篇 |
国内免费 | 224篇 |
专业分类
安全科学 | 834篇 |
废物处理 | 1064篇 |
环保管理 | 4054篇 |
综合类 | 4695篇 |
基础理论 | 8561篇 |
环境理论 | 22篇 |
污染及防治 | 7765篇 |
评价与监测 | 1743篇 |
社会与环境 | 1251篇 |
灾害及防治 | 191篇 |
出版年
2022年 | 180篇 |
2021年 | 180篇 |
2019年 | 215篇 |
2018年 | 387篇 |
2017年 | 380篇 |
2016年 | 560篇 |
2015年 | 491篇 |
2014年 | 680篇 |
2013年 | 2149篇 |
2012年 | 847篇 |
2011年 | 1264篇 |
2010年 | 1037篇 |
2009年 | 1040篇 |
2008年 | 1257篇 |
2007年 | 1339篇 |
2006年 | 1190篇 |
2005年 | 1010篇 |
2004年 | 1011篇 |
2003年 | 944篇 |
2002年 | 948篇 |
2001年 | 1243篇 |
2000年 | 861篇 |
1999年 | 552篇 |
1998年 | 427篇 |
1997年 | 436篇 |
1996年 | 444篇 |
1995年 | 482篇 |
1994年 | 440篇 |
1993年 | 395篇 |
1992年 | 414篇 |
1991年 | 373篇 |
1990年 | 377篇 |
1989年 | 411篇 |
1988年 | 347篇 |
1987年 | 300篇 |
1986年 | 276篇 |
1985年 | 306篇 |
1984年 | 286篇 |
1983年 | 322篇 |
1982年 | 322篇 |
1981年 | 272篇 |
1980年 | 243篇 |
1979年 | 269篇 |
1978年 | 229篇 |
1977年 | 195篇 |
1976年 | 201篇 |
1975年 | 192篇 |
1974年 | 173篇 |
1973年 | 171篇 |
1972年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
651.
The population dynamics of Mytilicola intestinalis Steuer in mussels (Mytilus edulis L.) from the River Lynher, Cornwall, England, have been studied over 3 years. By transplanting uninfested mussels from the River Erme, South Devon, into the Lynher mussel bed, the study was extended to the growth and development of new infestations under natural conditions. Female Mytilicola intestinalis are shown to breed twice, and two generations of parasites coexist for most of the year, with recruitment taking place in summer and autumn. One generation contributes its first brood to the autumn recruits before overwintering and contributing its second brood to the following summer's recruits. The other generation overwinters as juvenile and immature stages to contribute its two broods successively to the summer and autumn recruits. Environmental temperatures are believed to control the rates of development at all stages rather than acting as triggers in the onset or cessation of breeding at specific times. There is no evidence to support the contention that heavily infested mussels are killed, and parasite mortality is shown to be density-independent. 相似文献
652.
Phase relations between a circadian rhythm and its zeitgeber within the range of entrainment 总被引:1,自引:0,他引:1
The regular day-night changes in tissues, physiologic functions, and behavior of organisms are based on endogenous rhythmic processes which under constant conditions continue with periods slightly deviating from 24h. These ‘arcadian’ rhythms have properties of self-sustained oscillators. Under natural conditions, circadian rhythms are synchronized (entrained) to 24 h by periodic factors in the environment, the so-called ‘Zeitgebers’. In the laboratory, circadian rhythms can also be entrained to periods other than 24 h within certain limits. Data on the phase relationship between the circadian rhythm and an entraining light-dark cycle for vertebrates, insects, plants, and unicellular organisms are reviewed. 相似文献
653.
Duffy JC 《Disasters》1978,2(2-3):159-162
654.
655.
656.
657.
J.M.R. Hutchinson 《Environment international》1980,3(5):363-364
The development of traceability in low-level radioactivity measurements is discussed. The role that the development of large quantities of natural matrix standards can play is also discussed. 相似文献
658.
David J. Schaeffer Konanur G. Janardan Harold W. Kerster 《Environment international》1980,4(2):157-162
The “filter model” has been developed to explain the biologic effects of radiation and chemicals. We have examined nearly 300 sets of dose response data, of which 50 are presented here. Responses (induced by radiation and chemicals) which have been examined include in vitro survival studies on animal and plant tissues, induction of cellular aberrations and time to tumor or death. Similar data from in vivo studies has also been examined. All of the data appear to fit the model R = a lnD + b(lnD)2 + c, where R is the response, a and b are parameters fitted by regression to a particular set of data, and c is the response at zero (or lowest) dose. By writing this model in exponential form, it can be seen that the response R results from multistage filtering (by net amounts a and b) of the initial dose, D. The threshold is obtained from this model as the point, , at which the second derivative becomes zero. This is given by when a and b are oppositelt signed. 相似文献
659.
660.
John H Mutti J.David Richardson 《Journal of Environmental Economics and Management》1977,4(2):135-152
This paper demonstrates empirically the gain from adopting more general equilibrium approaches in projecting the effects on domestic output and international trade of environmental controls. The suggested models include a partial equilibrium case where all industries are treated independently, an intermediate case incorporating effects in supplying industries, and general equilibrium formulations based on alternative macroeconomic conditions. U. S. data is used to evaluate these models. Under both pollutor pays and subsidy financing schemes, moving from the simplest case to the intermediate model results in quite different industry projections. Including macroeconomic factors appears particularly important in the classical setting. 相似文献