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111.
Juan Moreno Santiago Merino Jaime Potti Ana de León Rosa Rodríguez 《Behavioral ecology and sociobiology》1999,46(4):244-251
We manipulated parental work load without changing brood size in a population of pied flycatchers Ficedula hypoleuca by removing two primaries (7 and 9) from each wing of females, thus reducing wing area and increasing flight costs. At other
nests, we offered supplementary food in the form of live mealworms (10–20 g daily from hatching) to reduce brood demand and
thus parental foraging costs. Other nests were left as controls. The daily energy expenditure of females feeding 12-day-old
nestlings was measured with doubly labelled water D2
18O. Females in both treatments expended the same amount of energy, fed at the same rate and had similar body masses to birds
in the control group. No effect of treatment on male mass and feeding effort was detected. More nestlings, however, died in
nests of handicapped females. Nestlings of handicapped females had significantly lower body mass and haematocrit values than
nestlings in food-supplemented nests, with nestlings in control nests occupying an intermediate position. The effects of both
treatments on nestling mass, haematocrit values and mortality rates were only noticeable in nests infested with mites. Maternal
energy expenditure is apparently constrained and offspring pay the costs imposed by reduced provisioning rate or increased
demand caused by ectoparasites, while receiving benefits when food supply improves. The presumption that avian reproductive
costs derive from changes in a flexible energy output may not be met in many cases.
Received: 24 October 1998 / Received in revised form: 15 March 1999 / Accepted: 26 April 1999 相似文献
112.
Behavioural research on domestic pigs has included parent–offspring conflict, sibling competition, and the use of signals
which influence resource allocation. In this paper, we review key sow–piglet behavioural studies and discuss their relevance
to resource allocation theory. Sibling competition begins in the uterus and continues after birth, as piglets compete directly
for access to the sow’s teats. This competition is made more severe by a unique dentition, which newborn piglets use to lacerate
the faces of siblings during teat disputes. Competition often leads to the death of some littermates, especially those of
low birth weight. Piglets also compete indirectly for milk, apparently by stimulating milk production at the teats that they
habitually use at the expense of milk production by other teats. The complex nursing behavior of the sow appears designed
to prevent the more vigorous piglets from monopolizing the milk. Sows give vocal signals which both attract piglets to suckle
and synchronize their behavior during nursing episodes. Piglets give loud vocal signals when separated from the sow; calls
which vary in intensity and appear to be honest signals of need. Udder massage by piglets may also serve as an honest signal
of need. Parent–offspring conflict has been demonstrated experimentally in pigs. Specifically, when given the opportunity
to control contact with their piglets, sows nurse less frequently, provide less milk, and lose less weight during lactation
than sows that cannot control their level of contact. Because of this interesting natural history and because they are so
amenable to experimentation, domestic pigs provide a rich system for testing ideas drawn from resource allocation theory.
This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson
and Fritz Trillmich). 相似文献
113.
Paolo Galeotti Diego Rubolini Fabio Pupin Roberto Sacchi Mauro Fasola 《Behavioral ecology and sociobiology》2008,62(11):1739-1745
Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting
in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior
to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped
after autotomy, could have great consequences for male sexual behaviour. We studied copulatory behaviour and sperm expenditure
of males paired to a mated female in Austropotamobius italicus, a freshwater crayfish species where both male and female mate multiply and where last-mating males are able to actively
remove previously deposited sperm. We aimed at assessing whether male sperm removal and expenditure varied according to sperm
allocated by first-mating males, and according to copulation behaviour and phenotypic traits (carapace length, chelae length
and relative chelae asymmetry) of second-mating males. Second-mating males did not adjust their ejaculate size in relation
to first-mating male ejaculate, nor to the first-mating male’s sperm removed. Moreover, the amount of sperm removed by second-mating
males increased with increasing first-mating males ejaculate size, and first-mating male sperm remaining after removal did
not correlate with the original first-mating male ejaculate size. Interestingly, the amount of sperm removed by second-mating
males decreased with increasing relative chelae asymmetry, while increasing with male body size. However, second-mating (but
not first-mating) asymmetric-clawed males produced larger ejaculates than symmetric-clawed ones. Importantly, the proportion
of second-mating male sperm remaining after the two matings did not vary with relative chelae asymmetry nor with body size
of second-mating males. Thus, small, asymmetric-clawed crayfish males appear to adopt sperm allocation tactics that allow
them to fully compensate for their inferior sperm removal ability. 相似文献
114.
在水环境保护长期受到高度重视的背景下,开展流域生态补偿试点是我国保护流域水环境的重要手段。目前我国多为政府主导型流域生态补偿,补偿资金全部来源于财政资金,提高财政支出效率可以让有限的财政资金发挥其最大效用。为明确流域生态补偿试点中的财政支出效率,本文以我国首个跨省界流域生态补偿试点——新安江流域生态补偿试点为案例对象,构建流域生态补偿财政支出效率评价模型,并建立评价指标体系。通过选取试点在2012—2017年的生态补偿财政支出进行效率测算与效率评价,结果显示,财政支出纯技术效率6年均值处在0.9以上的高水平,总体表现较好,但仍有改进空间;规模效率值较低是造成财政支出效率表现不佳的主要原因,生态补偿财政资金的配置规模急需完善。建议提高财政资金的管理水平,有针对性地实施生态补偿项目,建立流域和区域相结合的流域治理体系。 相似文献
115.
It has been argued that female mammals should terminate expensive forms of infant care earlier as habitat quality declines.
More recently it has been shown that among a variety of mammalian species, early termination of care is also associated with
highly favourable conditions. In this paper we present data on maternal investment decisions among baboons (Papio cynocephalus ursinus) inhabiting the Drakensberg Mountains of South Africa, and compare these with data from East African baboon studies. Mothers
in the mountain habitat face a set of environmental conditions where the problem of resource allocation to offspring is expected
to be particularly acute. We begin by using the model of Altmann (1980) of maternal time budgets to demonstrate that mountain
baboon mothers experience greater perturbations to their activity budgets while suckling than do mothers in other populations.
They also provide consistently greater levels of care to their infants and do so in the absence of any form of overt conflict
over access to the nipple. Although this investment results in a relative lengthening of the interbirth interval (IBI), it
is accompanied by relatively higher infant survival. We argue that factors that influence the maternal strategy adopted by
mountain baboons include slow infant growth rates and a lack of predation in the habitat which influences probability of offspring
survival beyond the immediate postnatal period. We suggest that both “care-dependent” sources of mortality (e.g. female reproductive
condition, the amount of milk transferred to offspring) as well as “care independent” sources of mortality (e.g. predation,
infectious disease) should be considered in studies of parental investment.
Received: 26 May 1997 / Accepted after revision: 9 August 1997 相似文献
116.
Christy A. Morrissey Stephen J. Ormerod 《Environmental pollution (Barking, Essex : 1987)》2010,158(2):447-7502
We combined stable isotope tracers of blood plasma, blood cells and egg contents with faecal analysis during pre-breeding and egg laying phases in two dipper species Cinclus cinclus and Cinclus mexicanus to determine the occurrence of dietary shifts during egg production and to assess consequences for egg contaminant loads. In both species, changes in δ13C (C. cinclus) or δ15N (C. mexicanus) in female plasma relative to red blood cells indicated a dietary shift during laying that was not observed in males. Eurasian dippers increased prey consumption as breeding approached, shifting from primarily trichopteran insect larvae to ephemeropterans and plecopterans. In American dippers, egg-laying females switched to feeding at a higher trophic level by consuming more fish. Eggs derived from higher trophic level diets contained more mercury (American dipper), polychlorinated biphenyls and some organochlorines, especially DDT metabolites. The results demonstrate how dietary changes during egg laying accompany the demands for egg production with consequences for contaminant deposition in avian eggs. 相似文献
117.
Cleber Broietti Leonardo Flach Suliani Rover João Antônio Salvador de Souza 《国际发展与全球生态学杂志》2018,25(7):630-641
Environmental expenditure can be classified as an indicator to measure the efforts of public agents with the environment. Cities and countries seek to understand the determinants of environmental spending over time. This research aims to analyze the variables that influence the environmental spending of Brazilian municipalities between the years 2012 and 2016. Thus, this research helps fill the gap on lack of longitudinal research that involves local contexts in relation to public municipal expenditures on the environment. The research method consists of the panel data model. Data were collected on the environmental expenditures of the municipalities and other variables of 4269 Brazilian municipalities, the collection generated 21,329 observations. The results showed that the municipalities of the state of Amapá had better relative expenditure averages, it was also observed that the municipalities in the Northeast region show the worst results. The municipality of Itamaracá, located in the state of Pernambuco, presented the best percentage of the country, 9.47% of the environmental expenditure in relation to total expenditure. Regarding the results of panel data, the variables revenue, population, density, GDP, and HDI presented significance in all models; the models estimated by fixed effects ensure the consistency of the parameters. 相似文献
118.
在分析科技投入体系的构成及环保科技投入的衡量指标基础上,研究政府和企业分别在环保产业科技投入体制中的机制;结论显示:必须强调企业科技投入的主体作用,并发挥其纽带作用;政府直接支持的科技投入具有杠杆作用,能够支持、引导和鼓励环保企业的研发投入。 相似文献
119.
O. Anne E. Rasa 《Behavioral ecology and sociobiology》1998,43(2):105-113
Parastizopus armaticeps is a nocturnal subsocial detritivorous desert tenebrionid that produces very few offspring per brood. The two environmental
factors that constrain reproduction, rapid sand desiccation rate and food scarcity, are countered by biparental effort. Males
dig and extend breeding burrows, maintaining their moisture level; females forage on the surface at night for high-quality
detritus, the larval food. This was shown to be a scarce and unpredictable resource for which there is high competition. When
food was supplemented in a field experiment, offspring number and survivorship doubled and burrow failure due to desiccation
dropped from approximately half, the typical failure rate for unsupplemented burrows, to zero. Food supplementation did not,
however, increase larval foodstore size and there was no difference in the size of the offspring produced. Supplemented females
reallocated their time, foraging less and digging more with the male. This change in maternal behaviour patterns resulted
in deeper burrows which remained moist longer, thus extending the larval production period. Female foraging efficiency, particularly
food retrieval speed, determined how much time females could allocate to digging, consequently increasing the reproductive
success of the pair. Burrow depth and sand moisture level at the burrow base were the major correlates of reproductive success,
but the scarcity and unpredictability of high-quality food on the surface and the competition for this resource influenced
the number of offspring indirectly through their effect on female behaviour.
Received: 29 November 1996 / Accepted after revision: 7 December 1997 相似文献
120.
Allan T. Bombard M.D. Sachiko Nakagawa Carolyn D. Runowicz Brian L. Cohen Magdy S. Mikhail Harold M. Nitowsky 《黑龙江环境通报》1994,14(12):1155-1157
We present two cases of abdominal pregnancy identified in our maternal serum screening programme—an additional, as yet unreported benefit of AFP+ (multiple analyte) maternal serum oncofetal antigen screening in pregnancy. 相似文献