首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   239篇
  免费   7篇
  国内免费   9篇
安全科学   5篇
废物处理   1篇
环保管理   101篇
综合类   61篇
基础理论   51篇
污染及防治   10篇
评价与监测   18篇
社会与环境   7篇
灾害及防治   1篇
  2024年   1篇
  2022年   4篇
  2021年   8篇
  2020年   1篇
  2019年   3篇
  2018年   4篇
  2017年   4篇
  2016年   5篇
  2015年   6篇
  2014年   11篇
  2013年   9篇
  2012年   10篇
  2011年   17篇
  2010年   15篇
  2009年   24篇
  2008年   19篇
  2007年   21篇
  2006年   12篇
  2005年   3篇
  2004年   7篇
  2003年   5篇
  2002年   2篇
  2001年   3篇
  2000年   5篇
  1999年   4篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1994年   1篇
  1992年   4篇
  1991年   4篇
  1989年   1篇
  1988年   1篇
  1987年   6篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1982年   2篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1978年   2篇
排序方式: 共有255条查询结果,搜索用时 856 毫秒
221.
通过分析现代物流对生态工业园建设带来的环境影响,论述了在可持续发展原则下的绿色物流战略;并以苏州新加坡工业园为例,探讨了绿色物流的发展模式,以及这种模式对生态工业园建设的意义。  相似文献   
222.
曹妃甸工业区水资源承载能力研究   总被引:1,自引:0,他引:1  
根据曹妃甸地区地表水和地下水资源异常紧缺、降水量不足、主要依靠跨区域调水的特点,综合考虑环境、人口、社会、经济等各方面要素,选取水资源子系统、生态环境子系统和社会经济发展子系统,并运用区域水资源规划管理理论,采用多目标规划技术建立了水资源承载力的多目标评价模型;结合按照各种发展模式设定的A,B,C,D四种情景,采用隶属度的方法分析计算了曹妃甸工业区2010,2020,2030年在A,B,C,D四种不同发展情景下的水资源承载力,得出A,B发展模式下曹妃甸工业区水资源准不可承载,C,D发展模式下可承载的模型预测结果;并针对评价结果,结合工业区实际情况,提出曹妃甸工业区提高水资源承载力的对策.  相似文献   
223.
Abstract:  The presence of indigenous people in tropical parks has fueled a debate over whether people in parks are conservation allies or direct threats to biodiversity. A well-known example is the Matsigenka (or Machiguenga) population residing in Manu National Park in Peruvian Amazonia. Because the exploitation of wild meat (or bushmeat), especially large vertebrates, represents the most significant internal threat to biodiversity in Manu, we analyzed 1 year of participatory monitoring of game offtake in two Matsigenka native communities within Manu Park (102,397 consumer days and 2,089 prey items). We used the Robinson and Redford (1991) index to identify five prey species hunted at or above maximum sustainable yield within the ∼150-km2 core hunting zones of the two communities: woolly monkey (Lagothrix lagotricha), spider monkey (Ateles chamek), white-lipped peccary (Tayassu pecari), Razor-billed Currasow (Mitu tuberosa), and Spix's Guan (Penelope jacquacu). There was little or no evidence that any of these five species has become depleted, other than locally, despite a near doubling of the human population since 1988. Hunter–prey profiles have not changed since 1988, and there has been little change in per capita consumption rates or mean prey weights. The current offtake by the Matsigenka appears to be sustainable, apparently due to source–sink dynamics. Source–sink dynamics imply that even with continued human population growth within a settlement, offtake for each hunted species will eventually reach an asymptote. Thus, stabilizing the Matsigenka population around existing settlements should be a primary policy goal for Manu Park.  相似文献   
224.
本文以生态旅游环境承载力理论为基础,初步构建了云南香格里拉普达措国家公园生态旅游环境承载力指标体系。通过实地考察和相关资料的查阅分析,对景区各分量承载力进行测算,得出景区生态旅游环境承载力的限制因子为资源空间承载力,景区的旅游环境承载力利用现状为全年弱载,而旅游旺季属于超载。针对计算和分析结果,提出了比较具体的调控措施,使景区的可持续发展具有建设意义。  相似文献   
225.
A modification of the Shechter-Lucas Wilderness Use Simulation Model (WUSM) for peak season boating on the Colorado River through Grand Canyon National Park, USA, is evaluated as a tool for making management decisions. A new microcomputer program to select trip itineraries for inclusion in the WUSM that was developed as part of this study is presented. This program simplifies user input and expands the WUSM's usefulness as a tool for management decisions by randomizing itinerary schedules based on probabilities developed from actual use of sites by canyon visitors. Model usefulness is demonstrated by simulating various management changes and comparing use levels of attraction sites and campgrounds as well as numbers of encounters between parties. The WUSM is being used as part of an ongoing study, to reflect the impact of fluctuating flow regimes through the turbines at Glen Canyon Dam on river trips.  相似文献   
226.
Vegetation and soil recovery in wilderness campsites closed to visitor use   总被引:3,自引:0,他引:3  
Recreational use of wilderness results in impacts to vegetation and soil in trails and campsites. Traditionally, campsite impact studies have compared campsites receiving various levels of use with unused control areas. Field studies in Sequoia National Park, California, indicate that the degree of impact to vegetation and soils also varies within campsites. The central areas of campsites, where trampling is concentrated, show lower plant species diversity, differences in relative species cover, more highly compacted soils, and lower soil nutrient concentrations than do peripheral, moderately trampled, and untrampled areas within the same campsite. Three years after closure to visitor use, the central areas show less increase in mean foliar plant cover, and soils remain more highly compacted than in previously moderately trampled areas of the same sites. Changes in relative species cover over time are used to assess both resiliency to trampling and species composition recovery within campsites closed to visitor use.  相似文献   
227.
The effect of past distributions of animal populations now extinct in an area from unknown causes is considered relative to their status as exotic or native in national parks. The example is the bison (Bisonbison) on the Copper and Chitina river drainages in Alaska in the USA which was introduced prior to establishment of Wrangell-St. Elias National Park and Preserve. The fossil record suggests that bison were present as recently as 500 years ago in Alaska. The policy of the US National Park Service to maintain natural ecosystems and restrict or eliminate exotic species raises the issue of whether this species should be treated as exotic or native.  相似文献   
228.
This paper describes the development and implementation ofPREPLAN, A Pristine Environment Planning Language and Simulator, for two conservation areas in Australia, Kosciusko National Park (New South Wales) and Tutanning Nature Reserve (Western Australia).PREPLAN was derived from the North American gradient modeling systems and theForest Planning Language and Simulator (FORPLAN), but includes unique characteristics not previously available.PREPLAN includes an integrated resource management data base, modules for predicting site-specific vegetation, fuels, animals, fire behavior, and fire effects, and an English language instruction set.PREPLAN was developed specifically to provide available information and understanding of ecosystems to managers in a readily accessible and usable form, and to provide the motivation to conduct additional required research projects. An evaluation of the system's advantages and limitations is presented, and the way the utilization of such systems is improving natural area decision making throughout Australia is discussed.  相似文献   
229.
Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon(DOC) concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia(DOC: 2.6–15.4 mg/L). Filtered(0.2 μm) and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations(p = 0.04) of photoreducible divalent mercury(Hg(II)RED)(mean of 754 ± 253 pg/L) than filtered samples(mean of 482 ± 206 pg/L);however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered(R~2= 0.43; p = 0.08) and unfiltered(R~2= 0.02; p = 0.71) samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg(Ⅱ)_(RED) in unfiltered(R2= 0.53; p = 0.04), but not in filtered samples(R~2= 0.04;p = 0.60). These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg(Ⅱ)_(RED) in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.  相似文献   
230.
森林旅游是生态旅游的重要形式之一,开展森林旅游已成为一种新的消费时尚,也是当今世界旅游的热点.介绍了神山国家森林公园优越的自然条件、丰富的森林旅游资源和人文旅游资源,分析了目前建设森林公园存在的问题,提出了发展森林旅游的建议.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号