全文获取类型
收费全文 | 41801篇 |
免费 | 538篇 |
国内免费 | 569篇 |
专业分类
安全科学 | 1342篇 |
废物处理 | 1582篇 |
环保管理 | 5919篇 |
综合类 | 6887篇 |
基础理论 | 11647篇 |
环境理论 | 27篇 |
污染及防治 | 10782篇 |
评价与监测 | 2424篇 |
社会与环境 | 1997篇 |
灾害及防治 | 301篇 |
出版年
2022年 | 318篇 |
2021年 | 319篇 |
2020年 | 312篇 |
2019年 | 323篇 |
2018年 | 596篇 |
2017年 | 592篇 |
2016年 | 868篇 |
2015年 | 750篇 |
2014年 | 997篇 |
2013年 | 3142篇 |
2012年 | 1301篇 |
2011年 | 1858篇 |
2010年 | 1507篇 |
2009年 | 1592篇 |
2008年 | 1821篇 |
2007年 | 1944篇 |
2006年 | 1690篇 |
2005年 | 1416篇 |
2004年 | 1423篇 |
2003年 | 1307篇 |
2002年 | 1298篇 |
2001年 | 1635篇 |
2000年 | 1183篇 |
1999年 | 755篇 |
1998年 | 578篇 |
1997年 | 588篇 |
1996年 | 594篇 |
1995年 | 658篇 |
1994年 | 580篇 |
1993年 | 532篇 |
1992年 | 532篇 |
1991年 | 503篇 |
1990年 | 505篇 |
1989年 | 522篇 |
1988年 | 455篇 |
1987年 | 391篇 |
1986年 | 382篇 |
1985年 | 408篇 |
1984年 | 428篇 |
1983年 | 426篇 |
1982年 | 448篇 |
1981年 | 386篇 |
1980年 | 340篇 |
1979年 | 374篇 |
1978年 | 294篇 |
1977年 | 265篇 |
1976年 | 251篇 |
1975年 | 253篇 |
1974年 | 242篇 |
1972年 | 266篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
Community response to hazard information 总被引:1,自引:0,他引:1
McKay JM 《Disasters》1984,8(2):118-123
The impact of flood hazard information on public acceptance of a selected flood mitigation strategy was assessed by an analysis of the content of newspaper reports of community reaction and letters to the editor. The impact of personal delivery of a flood hazard map on individual perception of risk and attitude to such information was assessed using personal interviews. The results indicated that media coverage of the flood hazard information reduced public criticism of the works. This result must be partially attributable to the dramatic style of media coverage and the fact that the media only emphasized the positive value of the works. The interview demonstrated that personal delivery of the information raised perception of risk, improved comprehension of flood risk, had no impact on acceptability of risk but discouraged some respondents from seeking such information in the future. Factors to explain the last negative change were identified to be the format of the map sheet and low salience of flood hazard. On the basis of all results, methods to improve community response to hazard information are provided. 相似文献
862.
863.
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
864.
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
865.
Duffy JC 《Disasters》1978,2(2-3):159-162
866.
867.
868.
The significant processes controlling the fate of particulates are convection an dispersion on one hand, and sedimentation on the other hand. Due to inteparticulated reactions, larger aggregates can be formed from smaller units thus changing the sedimentation characteristics. These phenomena are summarized in a mathematical model whereby hydrodynamic effects as well as the control mechanisms of the dissolved phase are included. A relationship was derived on the basis of energy considerations leading to the formulation of a critical sedimentation velocity of the suspensa, which determines the transport capacity of the flowing system. The sedimentation term is calculated from the above discussed transport capacity, hydro-dynamic parameters and suspending media properties. Aggregation effects are taken into account as an increase of sedimentation velocities of the particles. The equations are solved in a particular computational routine such that the horizontal distribution of suspended solids in a natural system can be describe as function of the above discussed phenomena. The model was tested with in situ-measurements. It was found that the observed processes are described satisfactorily by this model. 相似文献
869.
870.
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