全文获取类型
收费全文 | 627篇 |
免费 | 6篇 |
专业分类
安全科学 | 29篇 |
废物处理 | 5篇 |
环保管理 | 177篇 |
综合类 | 89篇 |
基础理论 | 246篇 |
环境理论 | 5篇 |
污染及防治 | 26篇 |
评价与监测 | 13篇 |
社会与环境 | 23篇 |
灾害及防治 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 2篇 |
2019年 | 17篇 |
2018年 | 14篇 |
2017年 | 18篇 |
2016年 | 32篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 31篇 |
2012年 | 6篇 |
2011年 | 23篇 |
2010年 | 18篇 |
2009年 | 64篇 |
2008年 | 55篇 |
2007年 | 51篇 |
2006年 | 46篇 |
2005年 | 22篇 |
2004年 | 24篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 20篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有633条查询结果,搜索用时 927 毫秒
101.
Timothy A. Linksvayer 《Behavioral ecology and sociobiology》2008,62(5):647-657
Conflicts of interest among genetically heterogeneous nestmates in social insect colonies have been emphasized as driving
colony resource allocation. However, potential intracolonial conflicts may not actually be realized so that resource allocation
could be shaped primarily by among-colony selection that maximizes colony productivity. To elucidate the causal basis of patterns
of resource allocation, I experimentally manipulated three fundamental aspects of colony social structure (relatedness among
workers, relatedness among larvae, and queen presence) in the ant Temnothorax curvispinosus and measured effects on colony resource allocation to new workers, gynes, and males. The experimental manipulations had widespread
effects on patterns of colony resource allocation, but there was little evidence for realized conflicts over the sex ratio
and caste ratio. Decreasing nestmate relatedness caused decreased colony productivity, suggesting that more closely related
nestmates have more favorably interacting phenotypes. Together, these results suggest that resource allocation in T. curvispinosus may be shaped more by among-colony selection than intracolonial conflict, leading to queen–worker–brood coadaptation. 相似文献
102.
Because American national forests are managed for all citizens, it is important that researchers explore the differences and
similarities between citizens living both near and far from publicly managed land. We surveyed residents living at various
distances from nationally managed land to collect resident perceptions of different forest fire-management techniques, to
determine public preferences for these techniques, and to examine the motivations behind these preferences. Participants both
close to and far away from national forests tended to favor a multipronged approach to fire management by preferring the use
of a combination of two or more fire-management techniques. There were no significant differences by proximity in participants’
self-rated emotions, types of fire-management techniques preferred, or the reasons and rationales for their preferred fire-management
technique(s), indicating that the proximity variable may not be as significant as previously thought. 相似文献
103.
We conducted case studies of three successful examples of collaborative, community-based natural resource conservation and development. Our purpose was to: (1) identify the functions served by interactions within the social networks of involved stakeholders; (2) describe key structural properties of these social networks; and (3) determine how these structural properties varied when the networks were serving different functions. The case studies relied on semi-structured, in-depth interviews of 8 to 11 key stakeholders at each site who had played a significant role in the collaborative projects. Interview questions focused on the roles played by key stakeholders and the functions of interactions between them. Interactions allowed the exchange of ideas, provided access to funding, and enabled some stakeholders to influence others. The exchange of ideas involved the largest number of stakeholders, the highest percentage of local stakeholders, and the highest density of interactions. Our findings demonstrated the value of tailoring strategies for involving stakeholders to meet different needs during a collaborative, community-based natural resource management project. Widespread involvement of local stakeholders may be most appropriate when ideas for a project are being developed. During efforts to exert influence to secure project approvals or funding, however, involving specific individuals with political connections or influence on possible sources of funds may be critical. Our findings are consistent with past work that has postulated that social networks may require specific characteristics to meet different needs in community-based environmental management. 相似文献
104.
Fluctuations of bird abundances in the Midwest region of the United States have been attributed to such factors as landscape change, habitat fragmentation, depredation, and supplemental feeding. However, no attempt has been made to estimate the collective role of landowner activities that may influence birds across a landscape. To investigate how landowners might influence birds when the majority (> 90%) of land is privately owned, we surveyed all 1694 private domestic landowners living on three breeding bird survey routes (120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan from October through December 2000. Our survey was designed to investigate (1) the proportion of landowners involved in bird feeding, providing bird houses, planting or maintaining vegetation for birds, gardening, landscaping, applying fertilizer, and applying pesticides or herbicides; (2) whether differences existed between urban, suburban, and rural landowner activities; and (3) whether landowners that carried out a given activity were sociodemographically different from those who did not. Of the 968 respondents (58.5% response rate), 912 (94%) carried out at least one of the activities on their land and the average landowner carried out 3.7 activities. A total of 65.6% fed birds, 45.7% provided bird houses, 54.6% planted or maintained vegetation for birds, 72.7% gardened, 72.3% landscaped, 49.3% applied fertilizer, and 25.2% applied pesticides or herbicides. Significant differences existed between the landscapes, with rural landowners having more bird houses and applying pesticides or herbicides in greater frequency. Similarly, urban landowners had a greater density of bird feeders and houses, but planted or maintained vegetation in the lowest frequency. Participation in activities varied by demographic factors, such as age, gender, and occupation. Scaling each activity to all landowners, including nonrespondents, across all landscapes indicates that between 14% and 82% of landowners may be engaged in a particular activity, with application of pesticides or herbicides having the least potential involvement (13.9%–55.4%) and gardening having the greatest potential involvement (40.1%–81.6%). Taken collectively, our results indicate that landowners are both intentionally and unintentionally engaged in a wide range of activities that are likely to influence bird populations. 相似文献
105.
106.
Jan Komdeur 《Behavioral ecology and sociobiology》1994,34(3):175-186
Prebreeding Seychelles warblers (Acrocephalus sechellensis) frequently act as helpers on their natal territory, aiding in territory defence, predator mobbing, nestbuilding, incubation (only females) and feeding dependent young of their parents. In some cases helpers could attain breeding status (e.g. by joint-nesting) in their natal group and become co-breeders. Comparisons of group size and reproductive success on a given quality territory suggest that the presence of alloparents (helpers and cobreeders) significantly affects the reproductive success of their parents. The influence of alloparents on reproductive success was examined by removing alloparents from breeding units and comparing the success of natural-sized and artificially reduced groups. Removal experiments, controlled for territory quality, group size and breeder age, showed that the presence of one alloparent significantly improved the reproductive success of its parents. Analysis strongly suggests that this was entirely due to helping behaviour (i.e. providing care to offspring of their parents), thereby improving the helper's inclusive fitness benefits from staying at home. However, these experiments showed also that the presence of two or more alloparents in medium-quality territories significantly decreased reproductive success, compared with groups with one alloparent. Several lines of evidence suggest that this may have been due to the joint-nesting and reproductive competition that could occur in breeding groups, or simply to resource depression when a large number of previous offspring remained on their natal territory. 相似文献
107.
Liselotte Sundström 《Behavioral ecology and sociobiology》1993,33(5):345-354
Summary The genetic population structure and the sociogenetic organization of the red wood ant Formica truncorum were compared in two populations with monogynous colonies and two populations with polygynous colonies. The genetic population structure was analysed by measuring allele frequency differences among local subsets of the main study populations. The analysis of sociogenetic organisation included estimates of nestmate queen and nestmate worker relatedness, effective number of queens, effective number of matings per queen, relatedness among male mates of nestmate queens and relatedness between queens and their male mates. The monogynous populations showed no differentiation between subpopulations, whereas there were significant allele frequency differences among the subpopulations in the polygynous population. Workers, queens and males showed the same genetical population structure. The relatedness among nestmate workers and among nestmate queens was identical in the polygynous societies. In three of the four populations there was a significant heterozygote excess among queens. The queens were related to their male mates in the polygynous population analysed, but not in the monogynous ones. The data suggest limited dispersal and partial intranidal mating in the populations with polygynous colonies and outbreeding in the populations having monogynous colonies. Polyandry was common in both population types; about 50% of the females had mated at least twice. The males contributed unequally to the progeny, one male fathering on average 75% of the offspring with double mating and 45–80% with three or more matings.
Correspondence to: L. Sundström 相似文献
108.
Carin Magnhagen 《Behavioral ecology and sociobiology》2007,61(4):525-531
The connection between risk-taking behaviour and exploratory behaviour in young-of-the-year perch (Perca fluviatilis) was studied in aquarium experiments to see whether individual behaviour patterns could be identified in this species and
also to investigate how individual behaviour is influenced by their social environment. Risk-taking was defined as the time
spent foraging in an open area vs hiding in the vegetation in the presence of a piscivore. Explorative behaviour was measured
as latency to enter a passage leading to an unknown area. Groups of four fish were used for the observations, and both behaviours
measured were positively correlated with the mean scores of these behaviours in the other group members. Risk-taking and explorative
behaviours were correlated only when data was adjusted for the behaviour of the other group members. Individuals that spent
more time in the open than their companions also tended to be faster than the others to enter the passage to the unknown area
and vice versa. The results indicate that there are consistent individual differences in boldness in perch, but also that
behaviour could be modified according to the behaviour of group members. 相似文献
109.
T.?FredstedEmail author C.?Pertoldi J.?M.?Olesen M.?Eberle P.?M.?Kappeler 《Behavioral ecology and sociobiology》2004,56(4):393-403
The objective of our study was to investigate the spatial distribution and genetic structure of a solitary primate at the microgeographical scale of adjacent local populations. We obtained spatial data and tissue samples for mtDNA analysis from 205 gray mouse lemurs (Microcebus murinus) captured along transects and within 3 grid systems within a 12.3 km2 area in Kirindy Forest, western Madagascar. Our capture data revealed that, even though the forest was continuous, gray mouse lemurs were not evenly distributed, and that daily and maximum dispersal distances were significantly greater in males. The frequency distribution of 22 mtDNA D-loop haplotypes was highly skewed. Nine haplotypes were unique to males, indicating male-mediated gene flow from surrounding areas. The geographic distribution of haplotypes revealed that males were also more dispersed than females. Females with the same haplotype showed a tendency towards spatial aggregation, and the correlation between genetic and geographic distances was higher in females. In several areas of the forest, however, spatially clustered females were not of the same haplotype, and females were not always found in clusters. Hence, in contrast to suggestions from previous studies, matrilineal clustering is not the only way females are socially organized. In addition, our study revealed heterogeneity and patterns in population structure that were not evident at smaller spatial scales, some of which may be relevant for designing conservation strategies.Communicated by C. Nunn 相似文献
110.
Marta C. Soares Sónia C. Cardoso Isabelle M. Côté 《Behavioral ecology and sociobiology》2007,61(7):1015-1022
Predation risk is amongst the most pervasive selective pressures influencing behaviour and animals have been repeatedly shown
to trade-off foraging success for safety. We examined the nature of this trade-off in cleaning symbioses amongst Caribbean
coral reef fishes. We predicted that cleaning gobies (Elacatinus evelynae and Elacatinus prochilos) should prefer fish clients that pose a low risk of predation (e.g. herbivores) over clients that may have more ectoparasites
but pose a higher risk (e.g. piscivores). Our field observations revealed that cleaners did clean preferentially client species
with more parasites but predatory and non-predatory clients had similar ectoparasite loads. Despite the lack of a foraging
advantage for inspecting predators, cleaners did not avoid risky clients. On the contrary, a larger proportion of visiting
predators than non-predators was inspected, gobies initiated more interactions with predatory clients, and predators were
attended to immediately upon arrival at cleaning stations. This preferential treatment of dangerous clients may allow the
rapid identification of cleaners as non-prey item or may be due to the effect of predators on the rest of the cleaners’ clientele,
which avoided cleaning stations whilst predators were present. Dealing with potentially risky clients may allow gobies to
regain access to their main food source: non-predatory clients. 相似文献