全文获取类型
收费全文 | 71篇 |
免费 | 6篇 |
国内免费 | 6篇 |
专业分类
安全科学 | 1篇 |
环保管理 | 12篇 |
综合类 | 7篇 |
基础理论 | 36篇 |
污染及防治 | 2篇 |
评价与监测 | 3篇 |
社会与环境 | 19篇 |
灾害及防治 | 3篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 8篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1993年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有83条查询结果,搜索用时 31 毫秒
61.
Typhenn A. Brichieri-Colombi Natasha A. Lloyd Jana M. McPherson Axel Moehrenschlager 《Conservation biology》2019,33(1):33-39
With the loss of biodiversity accelerating, conservation translocations such as reintroductions are becoming an increasingly common conservation tool. Conservation translocations must source individuals for release from either wild or captive-bred populations. We asked what proportion of North American conservation translocations rely on captive breeding and to what extent zoos and aquaria (hereafter zoos) fulfill captive breeding needs. We searched for mention of captive breeding and zoo involvement in all 1863 articles included in the North American Conservation Translocations database, which comprises journal articles and grey literature published before 2014 on conservation translocations in Canada, the United States, Mexico, the Caribbean, and Central America before 2014 as identified by a comprehensive literature review. Conservation translocations involved captive breeding for 162 (58%) of the 279 animal species translocated. Fifty-four zoos contributed animals for release. The 40 species of animals bred for release by zoos represented only 14% of all animal species for which conservation translocations were published and only 25% of all animal species that were bred for releases occurring in North America. Zoo contributions varied by taxon, ranging from zoo-bred animals released in 42% of amphibian conservation translocations to zero contributions for marine invertebrates. Proportional involvement of zoos in captive-breeding programs for release has increased from 1974 to 2014 (r = 0.325, p = 0.0313) as has the proportion of translocation-focused scientific papers coauthored by zoo professionals (from 0% in 1974 to 42% in 2013). Although zoos also contribute to conservation translocations through education, funding, and professional expertise, increasing the contribution of animals for release in responsible conservation translocation programs presents a future conservation need and opportunity. We especially encourage increased dialogue and planning between the zoo community, academic institutions, and governments to optimize the direct contribution zoos can make to wildlife conservation through conservation translocations. 相似文献
62.
The relationships between the phosphine content and various microbial populations,activities of different enzymes were investigated firstly.The results indicated that the phosphine content of samples from various environments was positively related to total anaerobic microorganisms,organic phosphate compound-dissolving bacteria,denitrifying bacteria,and the activities of alkaline phosphatase and dehydrogenase,with correlation coefficients (R~2) up to 0.93,0.90,0.69,0.79,and 0.82,respectively.Results also... 相似文献
63.
Estimator bias and efficiency for adaptive cluster sampling with order statistics and a stopping rule 总被引:2,自引:0,他引:2
Practical problems facing adaptive cluster sampling with order statistics (acsord) are explored using Monte Carlo simulation for three simulated fish populations and two known waterfowl populations. First, properties of an unbiased Hansen-Hurwitz (HH) estimator and a biased alternative Horvitz-Thompson (HT) estimator are evaluated. An increase in the level of population aggregation or the initial sample size increases the efficiencies of the two acsord estimators. For less aggregated fish populations, the efficiencies decrease as the order statistic parameter r (the number of units about which adaptive sampling is carried out) increases; for the highly aggregated fish and waterfowl populations, they increase with r. Acsord is almost always more efficient than simple random sampling for the highly aggregated populations. Positive bias is observed for the HT estimator, with the maximum bias usually occurring at small values of r. Secondly, a stopping rule at the Sth iteration of adaptive sampling beyond the initial sampling unit was applied to the acsord design to limit the otherwise open-ended sampling effort. The stopping rule induces relatively high positive bias to the HH estimator if the level of the population aggregation is high, the stopping level S is small, and r is large. The bias of HT is not very sensitive to the stopping rule and its bias is often reduced by the stopping rule at smaller values of r. For more aggregated populations, the stopping rule often reduces the efficiencies of the estimators compared to the non-stopping-rule scheme, but acsord still remains more efficient than simple random sampling. Despite its bias and lack of theoretical grounding, the HT estimator is usually more efficient than the HH estimator. In the stopping rule case, the HT estimator is preferable, because its bias is less sensitive to the stopping level. 相似文献
64.
Population viability analysis as a tool in wildlife conservation policy: With reference to Australia
David B. Lindenmayer Tim W. Clark Robert C. Lacy Virginia C. Thomas 《Environmental management》1993,17(6):745-758
Wildlife conservation policy for endangered species restoration follows a six-phase process. Population viability analysis
(PVA) can play a major contributing role in four of these. PVA, as discussed here, is a technique where extinction vulnerabilities
of small populations are estimated using computer simulation modeling. The benefits and limitations of using PVA in wildlife
decision and policy processes are reviewed based on our direct experience. PVA permits decision makers to set time frames
for management, estimate the required magnitude of restoration efforts, identify quantitative targets for species recovery,
and select, implement, monitor, and evaluate management strategies. PVA is of greatest value for rare species policy and management.
However, a limitation of PVA simulation models is that they are constrained by the amount of biological data available, and
such data are difficult to obtain from small populations that are at immediate risk of extinction. These problems may be overcome
with improved models and more data. Our experience shows benefits of PVA far outweigh its limitations, and applications of
the approach are most useful when integrated with decision analysis and completed within an adaptive management philosophy.
PVAs have been carried out for 14 Victorian species and less used elsewhere in Australia. Management and recovery plans are
developed from these PVAs. We recommend that PVA be used to guide research programs, develop conservation strategies, and
inform decision and policy making for both endangered and nonendangered species because it can significantly improve many
aspects of natural resource policy and management. 相似文献
65.
I. V. Tikhonova 《Russian Journal of Ecology》2007,38(5):306-310
The results of ten-year observations on fluctuations in the sex of individual trees and the sex structure of tree stands in two insular pine forests in the south of Central Siberia are presented. It is noted that the ratio of sex types of pine trees has markedly changed since 1998–1999. Significant correlations between the sex structure of stands and anomalies of the annual average air temperature have been recorded since the early 1990s. The male generative sphere of pine has changed to the greatest extent. Periodicity and delay in the change of shoot sexualization in response to changes in temperature are discussed. 相似文献
66.
JEFFREY T. FOSTER‡ ERIK J. TWEED RICHARD J. CAMP BETHANY L. WOODWORTH COREY D. ADLER TOM TELFER† 《Conservation biology》2004,18(3):716-725
Abstract: Within the last 30 years, five endemic bird species of the Alaka'i Swamp, Kaua'i, Hawai'i, have likely gone extinct. We documented population trends of the remaining avifauna in this time period to identify a common pattern in the Hawaiian Islands: decline of native species and expansion of introduced species. We conducted bird surveys over 100 km2 of the Alaka'i and Kōke'e regions of Kaua'i in March–April 2000 to estimate population size, distribution, and range limits of seven native and six introduced forest birds. We compared the results with four previous surveys conducted over the last 30 years. Five of the seven native species we studied have fared well, maintaining sizeable populations (>20,000 individuals) and unchanged or increasing numbers. The endemic 'Akikiki ( Oreomystis bairdi ), however, declined from 6296 (SE ± 1374) to 1472 (SE ± 680) individuals and exhibited range contraction from 88 to 36 km2 . The 'I'iwi ( Vestiaria coccinea ) also experienced a decline and contraction, though not as severe. Populations of several introduced forest birds are increasing, but all species, excluding the Japanese White-eye ( Zosterops japonicus ), were at low numbers (<5,500 individuals in survey area). One introduced species, the Japanese Bush-Warbler ( Cettia diphone ) recently invaded, whereas another, the Red-billed Leiothrix ( Leiothrix lutea ), has been extirpated. Two hurricanes in the past 20 years appear to have most strongly affected nectarivores and may have contributed to the decline or extinction of several other species. Overall, native bird populations on Kaua'i have exhibited species-specific responses to limiting factors. Although most native populations appear stable, the extant native avifauna is vulnerable as a result of limited distributions and the potential for widespread habitat degradation. 相似文献
67.
We investigate a community of independent logistically growing populations under a common harvesting effort which leads to the total maximum sustainable yield (TMSY). It is surprising that in the case of two populations with approximately equal carrying capacities, TMSY is reached while both populations persist, although their biotic potential may differ substantially. In general, however, TMSY with a common harvesting effort implies suboptimal fishing of some populations, overfishing of others and extinction of the rest of the populations. Since extinction of populations is a rule rather than an exception and since a community of independent populations is more robust than an ecosystem with multiple trophic levels, we call for urgent retraction of all legal documents advocating MSY in ecosystems. 相似文献
68.
Although the genetic and ecological effects of population declines in endangered species have been well studied, little is known of the social consequences. Changes in signaling behavior may result in disrupted communication and affect both reproductive and conflict‐resolution activities. The North Island Kōkako (Callaeas wilsoni) is an endangered, duetting (i.e., alternating, coordinated singing by mated pairs) songbird endemic to New Zealand temperate rain forests. Scattered populations (approximately 1500 individuals in 13 surviving and 11 translocated populations) in isolated conservation areas of different sizes have been rescued from extirpation and are currently recovering. We examined key song attributes of the Kōkako to assess whether population size or growth rate are related to song complexity, the reduction of which may compromise effective communication. We analyzed song repertoire size and phrase‐type sharing (i.e., Jaccard index of similarity), vocal performance (singing rates, song switching rates, and diversity of phrase types), and song syntactical characteristics (i.e., unpredictability in sequences of phrase types) in surviving and translocated populations (populations of approximately 19–250 territorial individuals). Population size was positively correlated with a population's song repertoire, song diversity, and switching of song phrase types and negatively correlated with shared phrase types and variation in syntactical structure of songs. Population growth rate correlated positively with pair repertoire size, population repertoire size, and singing rates during song bouts. As for solo‐singing species in fragmented landscapes, songs in the fragmented populations of Kōkako appear to be undergoing microevolution as occurs in island colonization events. Our results suggest that vocal changes in small populations could affect population establishment and growth, particularly in multiple‐source translocations. We believe measurement of vocal behavior could be used as a supplement to periodic population censuses to allow more frequent monitoring of population size. Efectos de la Conducta de Canto sobre el Tamaño Poblacional de una Ave Canora Rara 相似文献
69.
Uscher-Pines L 《Disasters》2009,33(1):1-22
This paper reviews the literature on the effects of post-disaster relocation on physical and mental heath, and develops a conceptual framework to guide future research. Forty articles were selected for full-text review and incorporation into the conceptual framework. Twenty-four articles were reviewed for results and methodology. These overwhelmingly tracked mental health outcomes. Only four (16 per cent) focused on physical health. Eight of ten showed an association between relocation and psychological morbidity. Certain outcomes (such as mortality, injury and cardiovascular disease risk factors) revealed inconsistent results, but these were rarely studied. Despite the frequency of post-disaster relocation and evidence of its effect on psychological morbidity, there is a relative paucity of studies; the few examples in the literature reveal weak study designs, inconsistent results, and inattention to physical health impacts and the challenges facing vulnerable populations. Further research guided by theory is needed to inform emergency preparedness and recovery policy. 相似文献
70.
Spinal deformities are seen in fishes. Deformities in the family Syngnathidae is rarely reported. Spine curvatures in natural population of pipefish, Syngnathus abaster are reported from the Tunis North Lake. The species is euryhaline and occurs along the Mediterranean coasts. Four hundred specimens of S. abaster were collected from January 2006 to December 2007 from the Tunis North Lake. Two specimens with skeletal abnormalities were described for the first time. X-rays radiographies revealed several vertebral deformities for each deformed specimen, especially at five curvation places of the caudal part. Several factors are believed to be the cause of spinal deformities of S. abaster in the Tunis North Lake, such as environmental disturbances, parasitism infection and nutritional factors. 相似文献