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   78篇
  免费   2篇
安全科学   1篇
环保管理   10篇
综合类   4篇
基础理论   36篇
污染及防治   28篇
灾害及防治   1篇
  2015年   2篇
  2014年   2篇
  2013年   27篇
  2012年   1篇
  2011年   1篇
  2007年   1篇
  2006年   4篇
  2005年   5篇
  2004年   3篇
  2003年   3篇
  2002年   1篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
  1995年   3篇
  1992年   1篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1988年   2篇
  1986年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1970年   1篇
排序方式: 共有80条查询结果,搜索用时 46 毫秒
51.
Cheese, Tourists, and Red Pandas in the Nepal Himalayas   总被引:3,自引:0,他引:3  
  相似文献   
52.
53.
We assessed relationships between the extent to which farmers reported exposure to relevant information and their attitudes towards, knowledge about, and degree of adoption of riparian management strategies. We also examined associations between knowledge of, or receipt of, financial assistance for riparian fencing/planting and intentions for and extent of adoption of this strategy. A mail survey of 718 pastoral farmers in Otago and Southland in New Zealand [294 surveys returned (41%)] yielded 279 usable questionnaires. Indices were developed to reflect range and frequency of information use and range of practices adopted. Attitudes were measured using Likert-type responses to 11 statements, and knowledge as a score on a ten-question true/false test. Positive relationships between information and the three main response variables (attitude, knowledge, and adoption) were weak but significant and systematic. These associations remained significant when important demographic and farm characteristics were taken into account. Informed farmers were more likely to report intentions to carry out riparian fencing or planting within the next year. Farmers who were aware that funding was available were also more likely to state this intention, independent of information level. The reported extent to which waterways had been fenced to exclude stock was related to receipt of funding, but not to information level. Financial factors were the most influential barrier preventing adoption of permanent fencing. Our research shows a positive correlation between the receipt of information and funding and the adoption of specific riparian management measures.  相似文献   
54.
The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions, can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands.  相似文献   
55.
A 27-year-old gravida 4, para 3 was found to have anhydramnios at 14 weeks' gestation following a size/date discrepancy noted at her routine prenatal visit. A detailed ultrasound revealed multiple fetal anomalies including congenital heart defect, chest hypoplasia, and bilateral dysplastic kidneys. Karyotype revealed trisomy 16 in 15/15 cells from a tissue specimen obtained from the fetal cord insertion site following elective pregnancy termination.  相似文献   
56.
57.
The ECHA Biocide Monitor, a dipstick procedure originally designed to test the effectiveness of in situ biocides, was evaluated as a possible environmental toxicity assessment procedure. The dipstick procedure was applied to 94 sediment extracts which were also tested by three well documented toxicant screening procedures; Microtox, Daphnia magna and Spirillum volutans. In these samples the Daphnia magna test proved to be the most sensitive indication of toxicant activity (63 of 94) with the ECHA Biocide Monitor easily being the second most sensitive procedure with 27 of 94 sediments indicating the presence of toxic substances. Results of the investigation are detailed.  相似文献   
58.
Abstract:  The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km2/year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist-netting program in 1– to 100-ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the condition of second growth immediately surrounding fragments was often as important as fragment size or local forest cover in explaining variation in abundance. Some fragments surrounded by 100 m of open pasture showed reductions in insectivorous bird abundance of over 95%, even in landscapes dominated by continuous forest and old second growth. These extreme reductions may be typical throughout Amazonia in small (≤10 ha), isolated fragments of rainforest. Abundance for some guilds returned to preisolation levels in 10- and 100-ha fragments connected to continuous forest by 20-year-old second growth. Our results show that the consequences of Amazonian forest loss cannot be accurately described without explicit consideration of vegetation dynamics in matrix habitat. Any dichotomous classification of the landscape into "forest" and "nonforest" misses essential information about the matrix.  相似文献   
59.
A Mesofilter Conservation Strategy to Complement Fine and Coarse Filters   总被引:5,自引:1,他引:5  
Abstract:  Setting aside entire ecosystems in reserves is an efficient way to maintain biodiversity because large numbers of species are protected, but ecosystem conservation constitutes a coarse filter that does not address some species. A complementary, fine-filter approach is also required to provide tailored management for some species (e.g., those subject to direct exploitation). Mesofilter conservation is another complementary approach that focuses on conserving critical elements of ecosystems that are important to many species, especially those likely to be overlooked by fine-filter approaches, such as invertebrates, fungi, and nonvascular plants. Critical elements include structures such as logs, snags, pools, springs, streams, reefs, and hedgerows, and processes such as fires and floods. Mesofilter conservation is particularly appropriate for seminatural ecosystems that are managed for both biodiversity and commodity production (e.g., forests managed for timber, grasslands managed for livestock forage, and aquatic ecosystems managed for fisheries) and is relevant to managing some agricultural and urban environments for biodiversity.  相似文献   
60.
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