全文获取类型
收费全文 | 785篇 |
免费 | 18篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 41篇 |
废物处理 | 9篇 |
环保管理 | 197篇 |
综合类 | 132篇 |
基础理论 | 275篇 |
环境理论 | 5篇 |
污染及防治 | 52篇 |
评价与监测 | 39篇 |
社会与环境 | 47篇 |
灾害及防治 | 26篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 24篇 |
2020年 | 6篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 22篇 |
2016年 | 39篇 |
2015年 | 23篇 |
2014年 | 26篇 |
2013年 | 38篇 |
2012年 | 21篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 71篇 |
2008年 | 63篇 |
2007年 | 58篇 |
2006年 | 50篇 |
2005年 | 40篇 |
2004年 | 33篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 23篇 |
1999年 | 17篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有823条查询结果,搜索用时 62 毫秒
151.
沙尘暴是一种气象灾害,也是严重的生态环境问题.它对自然环境和经济社会的危害已越来越引起人类的重视.随着环境遥感的发展,运用遥感技术对沙尘暴进行监测是最有效的方法之一.文章通过对中国沙尘暴遥感监测研究的现状的概述以及对当前遥感应用的技术水平的分析,展望了未来遥感监测沙尘暴的发展趋势. 相似文献
152.
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
153.
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
154.
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
155.
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
156.
On the sustainability of common property resources 总被引:2,自引:0,他引:2
Nuria Oss-Eraso Montserrat Viladrich-Grau 《Journal of Environmental Economics and Management》2007,53(3):393-410
We provide a model where a common property resource is managed by two types of agents, cooperators and non-cooperators, who adjust their extraction strategies in response to persistent differential payoffs. In our model, the social approval of cooperators works as a reward mechanism which, as we show, favors both the pervasiveness of cooperative behavior and the sustainable management of natural resources. Specifically, we show that in the presence of such a reward mechanism a stable equilibrium can be reached with both strategies being practiced simultaneously and a decentralized and sustainable management of common property resources is possible. 相似文献
157.
?ystein?HolandEmail author Robert?B.?Weladji Hallvard?Gj?stein Jouko?Kumpula Martin?E.?Smith Mauri?Nieminen Knut?H.?R?ed 《Behavioral ecology and sociobiology》2004,57(1):69-76
In polygynous mammals, high-quality females may increase their fitness by providing superior care to their offspring. Based on the agonistic interactions of female reindeer in an experimental herd during two consecutive years (1997 and 1998), we tested whether maternal social rank influenced: (1) winter body-mass change of females, (2) preparturition reproductive effort (measured as fecundity, the birth mass and the birth date of their calves), (3) preweaning maternal effort (measured as calves preweaning mortality, early preweaning and late preweaning growth rate and September body mass of calves), and (4) postweaning maternal effort (measured as calves body-mass change during their first winter). In the models, we included September females body mass as a covariate to separate the effects of maternal rank and body mass. We also tested whether the effect of social rank on maternal efforts was dependent on offspring sex. High-ranked females gained body mass whereas low-ranked females lost weight during the winter. Fecundity was higher and date of birth was earlier in high-ranked females than in subordinates, whereas no effect of females rank on birth mass of calves was found. Early preweaning growth rate and September body mass of calves increased with increasing females social rank, whereas late preweaning daily growth rate of calves was not influenced by females rank. Calves preweaning mortality was only influenced by year, which also explained most of the variance in the winter body-mass change of calves. The effects of females rank on the reproductive-efforts parameters studied were not specific to offspring sex. These findings suggest that females rank influences reproductive effort during the preparturition, as well as the preweaning, period, the effect being sex independent.Communicated by R. Gibson 相似文献
158.
Cédric Alaux Malvina Boutot Pierre Jaisson Abraham Hefetz 《Behavioral ecology and sociobiology》2007,62(2):213-222
Worker sterility in the bumblebee Bombus terrestris is conditional and is linked to the social development of the colony. Workers refrain from reproducing or overtly challenging
the queen until gyne production has initiated, at the so-called competition point (CP). It is not known whether this behavior
is hard-wired or workers show reproductive plasticity. It also remains unclear whether worker reproductive decision is under
queen and/or worker control. In this study, we tested worker reproductive plasticity in an attempt to assess whether and under
which conditions worker sterility/fertility are reversible. We introduced egg-laying workers into colonies with different
social structures for 1 week then monitored their reproductive status. We revealed a remarkable reproductive plasticity in
the introduced workers that was social-condition-dependent. In the presence of a pre-CP queen, the introduced workers reverted
to sterility, whereas in the presence of a post-CP queen, such workers remained egg-layer. Reversion to sterility does not
occur when direct contact with the queen is prevented, as the introduced workers remained egg-layer in the queenright colonies
with a confined queen. Egg-laying workers that were introduced into queenless colonies mostly maintained their fertility regardless
of colony social phase. This shows that worker transition from cooperative to selfish behavior is reversible depending on
the social context. 相似文献
159.
Sociality in some birds, mammals, and social insects was suggested to have evolved through the lengthening and extension of
parental care behaviors to nondirect descendents. In these systems, group members care for young cooperatively and, thus,
increase the reproductive success of the breeders and fitness of the young. Parental care behaviors, such as regurgitation
feeding and matriphagy (consumption of the mother), occur in several subsocial and social spiders. However, it is not known
whether females in a colony cooperate in caring for the young of other females and whether such cooperative care improves
reproductive success. To answer this question, we created experimental colonies of the social spider Stegodyphus dumicola (Araneae, Eresidae), allowing only one female in a group to produce young, simulating reproductive skew occurring in nests
in nature. In this paper, we show for the first time that females of S. dumicola cooperate in providing regurgitated food for young of other females and are even eaten by those young. Young raised by a
group of females were larger and had greater survival than young raised only by their mother. Thus, fitness benefits from
raising broods cooperatively may have favored the evolution of sociality in spiders. 相似文献
160.
Brooke L. Sargeant Aaron J. Wirsing Michael R. Heithaus Janet Mann 《Behavioral ecology and sociobiology》2007,61(5):679-688
Because behavioral variation within and among populations may result from ecological, social, genetic and phenotypic differences,
identifying the mechanism(s) responsible is challenging. Observational studies typically examine social learning by excluding
ecological and genetic factors, but this approach is insufficient for many complex behaviors associated with substantial environmental
variation. Indian Ocean bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia show individual differences in foraging tactics, including possible tool use with marine
sponges and social learning may be responsible for this diversity. However, the contributions of ecological factors to the
development of these foraging tactics were not previously investigated. Here, we determined the relationship between ecological
variables and foraging tactics and assessed whether differences in habitat use could explain individual differences in foraging
tactics. We monitored 14 survey zones to identify how foraging tactics were spatially distributed and matched behavioral data
to the ecological variables within each zone. Three of four foraging tactics were significantly correlated with ecological
characteristics such as seagrass biomass, water depth, presence of marine sponges and season. Further, individual differences
in habitat use were associated with some tactics. However, several tactics overlapped spatially and previous findings suggest
demographic and social factors also contribute to the individual variation in this population. This study illustrates the
importance of environmental heterogeneity in shaping foraging diversity and shows that investigating social learning by ruling
out alternative mechanisms may often be too simplistic, highlighting the need for methods incorporating the relative contributions
of multiple factors. 相似文献