全文获取类型
收费全文 | 171篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 17篇 |
废物处理 | 4篇 |
环保管理 | 40篇 |
综合类 | 15篇 |
基础理论 | 32篇 |
污染及防治 | 41篇 |
评价与监测 | 19篇 |
社会与环境 | 4篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 15篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有175条查询结果,搜索用时 312 毫秒
101.
The fisher (Martes pennanti) has recently recovered from historic extirpations across much of its geographic range. There are at least five explanations for the recovery of the fisher, including changes in the amount of habitat, the suitability of habitat, trapping pressure, societal attitudes toward predators, and climate. We evaluated a recovering fisher population in Ontario to test two conditions we viewed as necessary to support the hypothesis that fisher populations have increased due to an increase in the amount of forested land. First, we tested whether the amount of forested land has increased. Second, we tested whether contemporary fisher abundance (and therefore habitat quality) was related to the amount of forest. Topographic maps showed that the proportion of forested land in the study area had increased by 1.9% per decade since 1934 and 3.3% per decade since 1959, likely as a result of land conversion from agricultural uses. Overall the proportion of the study area that was forested increased from 29% to 40% during 1934 to 1995. Census data from the region indicated that there had been a decline in the amount of land area being farmed during the last 50 years. Recent livetrapping data showed that fisher abundance was positively related to the proportion of landscapes that were forested. Based on our results, we could not reject the hypothesis that an increase in the amount of forested land has contributed to the recovery of fisher populations. 相似文献
102.
Effects of uncertainty and variability on population declines and IUCN Red List classifications
下载免费PDF全文
![点击此处可从《Conservation biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pamela Rueda‐Cediel Kurt E. Anderson Tracey J. Regan Helen M. Regan 《Conservation biology》2018,32(4):916-925
The International Union for Conservation of Nature (IUCN) Red List Categories and Criteria is a quantitative framework for classifying species according to extinction risk. Population models may be used to estimate extinction risk or population declines. Uncertainty and variability arise in threat classifications through measurement and process error in empirical data and uncertainty in the models used to estimate extinction risk and population declines. Furthermore, species traits are known to affect extinction risk. We investigated the effects of measurement and process error, model type, population growth rate, and age at first reproduction on the reliability of risk classifications based on projected population declines on IUCN Red List classifications. We used an age‐structured population model to simulate true population trajectories with different growth rates, reproductive ages and levels of variation, and subjected them to measurement error. We evaluated the ability of scalar and matrix models parameterized with these simulated time series to accurately capture the IUCN Red List classification generated with true population declines. Under all levels of measurement error tested and low process error, classifications were reasonably accurate; scalar and matrix models yielded roughly the same rate of misclassifications, but the distribution of errors differed; matrix models led to greater overestimation of extinction risk than underestimations; process error tended to contribute to misclassifications to a greater extent than measurement error; and more misclassifications occurred for fast, rather than slow, life histories. These results indicate that classifications of highly threatened taxa (i.e., taxa with low growth rates) under criterion A are more likely to be reliable than for less threatened taxa when assessed with population models. Greater scrutiny needs to be placed on data used to parameterize population models for species with high growth rates, particularly when available evidence indicates a potential transition to higher risk categories. 相似文献
103.
104.
The conservation of rare plant species hinges on our ability to identify the underlying mechanisms that limit rare plant populations. Theory on rarity suggests that both predispersal seed predation and competition can be important mechanisms influencing abundance and/or distribution of rare plant populations. Yet few studies have tested these interactions, and those that have evaluated each mechanism independently. Astragalus sinuatus Piper (Whited's milkvetch) is a narrow endemic plant species restricted to eight populations within a 10-km2 area in eastern Washington. We used experimental and observational methods to test the effects of native insect predispersal seed predators and an invasive grass (Bromus tectorum L. [cheatgrass]) on seed set and population density of A. sinuatus. We quantified per capita seed production and pod predation rates across four sites and among four years. Seed predation rates were high across four sites (66-82%) and all years (65-82%). Experimental reduction of predispersal seed predators significantly increased per capita seed set of A. sinuatus (164-345%) at two experimental sites. Concurrently, two seed addition experiments demonstrated the effect of seed loss and presence of B. tectorum on seedling recruitment and establishment of A. sinuatus over four growing seasons. In the first seed addition experiment, we found no difference in recruitment and establishment between low (40) and high (120) seed addition levels. In the second addition experiment (one level of addition; 40 seeds), we found that recruitment and survivorship increased 200% in plots where B. tectorum was removed compared to plots where B. tectorum was present. Thus, seed addition had no impact in the presence of B. tectorum; conversely, in the absence of B. tectorum, seed addition was highly effective at increasing population numbers. Results suggest that, in areas where B. tectorum is present, recruitment is site limited, and it is seed limited when B. tectorum is absent. We recommend that managers reduce B. tectorum in an effort to increase population growth of A. sinuatus; in areas where B. tectorum is absent, short-term reduction of insect predators should be considered as a strategy to increase population growth of this rare species. 相似文献
105.
Alain?DejeanEmail author James?M.?Carpenter Bruno?Corbara Pamela?Wright Olivier?Roux Louis?M.?LaPierre 《Die Naturwissenschaften》2012,99(4):265-273
Here we show that trying to rob prey (cleptobiosis) from a highly specialized predatory ant species is risky. To capture prey,
Allomerus decemarticulatus workers build gallery-shaped traps on the stems of their associated myrmecophyte, Hirtella physophora. We wondered whether the frequent presence of immobilized prey on the trap attracted flying cleptoparasites. Nine social
wasp species nest in the H. physophora foliage; of the six species studied, only Angiopolybia pallens rob prey from Allomerus colonies. For those H. physophora not sheltering wasps, we noted cleptobiosis by stingless bees (Trigona), social wasps (A. pallens and five Agelaia species), assassin bugs (Reduviidae), and flies. A relationship between the size of the robbers and their rate of capture
by ambushing Allomerus workers was established for social wasps; small wasps were easily captured, while the largest never were. Reduviids, which
are slow to extract their rostrum from prey, were always captured, while Trigona and flies often escaped. The balance sheet for the ants was positive vis-à-vis the reduviids and four out of the six social
wasp species. For the latter, wasps began by cutting up parts of the prey’s abdomen and were captured (or abandoned the prey)
before the entire abdomen was retrieved so that the total weight of the captured wasps exceeded that of the prey abdomens.
For A. pallens, we show that the number of individuals captured during attempts at cleptobiosis increases with the size of the Allomerus’ prey. 相似文献
106.
107.
108.
The present study examines the impact of behavioral control on the experience of work strain under conditions of work overload. Extending experimental laboratory findings that suggest that control can lessen the impact of aversive stimuli on psychological and physiological strain responses, we hypothesized an interaction between control and workload such that the effects of high demands on strain would be less if the worker had behavioral control over the task. This hypothesis is also consistent with Karasek's job demands-job decision latitude model of work strain and health. The hypothesis was tested in a laboratory experiment in which 125 subjects worked on a mail sorting task with either a high or moderate level of workload and either a high or low level of behavioral control. Strain responses were assessed with measures of job satisfaction, anxiety, and physiological arousal. The hypothesis was only partially supported in that high control lessened the impact that work overload had on anxiety. While not fully supportive of the model, the results are seen as conservative given the constraints on the manipulation of work overload inherent in the laboratory environment. 相似文献
109.
Dalton TM 《Journal of environmental management》2004,70(4):333-349
Marine protected areas (MPAs) are one tool that can be used in the comprehensive management of human activities in areas of the ocean. Although researchers have supported using MPAs as an ecosystem management tool, scientific research on MPAs in areas other than fisheries and fisheries management is limited. This paper presents a model for designing marine protected areas that protect important components of the ecosystem while minimizing economic impacts on local communities. This model combines conservation principles derived specifically for the marine environment with economic impact assessment. This integrated model allows for consideration of both fishery and non-fishery resources and activities such as shipping and recreational boating. An illustration of the model is presented that estimates the total economic impacts on Massachusetts' coastal counties of restricting fishing and shipping at certain sites in an area in the southern Gulf of Maine. The results suggest that the economic impacts on the region would differ according to the site in which shipping and fishing were restricted. Restricting activities in certain sites may have considerable impacts on local communities. The use of the model for evaluating and comparing potential MPA sites is illustrated through an evaluation of three different policy scenarios. The scenarios demonstrate how the model could be used to achieve different goals for managing resources in the region: protecting important components of the ecosystem, minimizing economic impacts on the local region, or a combination of the two. 相似文献
110.
INTRODUCTION: Many injury prevention interventions require changes in human behavior to reduce self-risk or risk to others. Promising injury prevention interventions may be discarded if they lack power to create a significant difference in outcomes when judging their ability to "move a person from nonaction or negative action to positive action (safety)." The transtheoretical model of change (TMC) allows greater sensitivity in detecting along the change process where an intervention may be effective. The stages of change consist of precontemplation, contemplation, preparation, action, maintenance, and termination. Change is not viewed as an "all or none phenomenon." METHOD: Use of the TMC was examined using a quasiexperimental, cross-over design involving high school agriculture students enrolled in 21 schools in Kentucky (n=9), Iowa (n=7), and Mississippi (n=5). A series of physical and narrative simulations (safety training exercises) were developed with a focus on preventing amputation, spinal cord injury, hypersensitivity pneumonitis, and noise-induced hearing loss. Contemplation and action, as part of the TMC, were measured using a 10-item, Likert-type, stages of change (SOC) instrument comprised of two subscales (reliability coefficients were.88 and.81, respectively). The final sample consisted of 790 students (373 treatment and 417 control). RESULTS: There was a significant group effect for both contemplation, F(1,732)=197.4; p<.0001, and action, F(1,730)=106.1; p<.0001. A convenience sample of 29 of the participating students was selected for follow-up farm visits 1 year postparticipation. Of these students, 25 (86%) had made safety behavior changes in their farm work. IMPACT ON INDUSTRY: The use of the TMC model can provide researchers with greater precision in examining intervention effectiveness in promoting change. 相似文献