全文获取类型
收费全文 | 86篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 4篇 |
环保管理 | 3篇 |
综合类 | 22篇 |
基础理论 | 44篇 |
污染及防治 | 12篇 |
评价与监测 | 2篇 |
社会与环境 | 2篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 11篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 875 毫秒
71.
Male costs and benefits associated with male display size in field populations of an Australian lekking Drosophila species were examined. Results suggested that male mating success increased with display size, since matings appeared to
be more common in large displays, and since the probability of males encountering a female increased as displays contained
more males. Female encounter probabilities did not increase once about 20 males or more were present on a display. Male size
and fighting costs tended to increase with display size. The distribution of males among displays did not follow the ideal
free distribution in the sense that each male did not have equal mating opportunity per unit time. Deviation from an ideal
free distribution may have been due to female preference for mating in aggregations rather than with solitary males, since
in a field experiment females were more willing for mating in an aggregation of five males than with solitary males.
Received: 22 May 1997 / Accepted after revision: 1 November 1997 相似文献
72.
In long-lived seabirds with low annual reproductive output, the renesting decision after breeding failure is critical, and
the parents have to weigh benefits of replacement clutches against possible future reproductive costs. In this study, we investigated
factors influencing renesting decisions in common terns (Sterna hirundo) and compared aspects of breeding biology and body mass between two breeding attempts by the same pairs in each of 4 years
of heavy losses due to predation. Renesting birds were characterized by early laying dates and by a high age. Among early
breeders, high egg mass reduced the probability of renesting. A long relaying interval coincided with low mass of replacement
eggs in one year, and short intervals with high egg mass in another. Further, egg mass decreased and relaying intervals increased
the later the predation events occurred. Evidence of high levels of parental care of replacement clutches came from body mass
data: female mass increase prior to egg laying was higher in the second attempt than in the first, whereas male mass was lower
during the second courtship period than during the first. Male mass also affected relaying intervals and mass of replacement
eggs. We conclude that common terns expend high levels of parental care of replacement clutches. Intrinsic factors related
to individual quality (age, body condition) seemed most important for renesting decisions and for the degree of parental care,
but foraging conditions seemed to have modifying effects.
Received: 13 August 1999 / Received in revised form: 5 February 2000 / Accepted: 13 March 2000 相似文献
73.
Bird DJ Rotchell JM Hesp SA Newton LC Hall NG Potter IC 《Environmental pollution (Barking, Essex : 1987)》2008,151(3):641-651
We explored how hepatic [metal]s in Anguilla anguilla at a contaminated estuarine site are influenced by body size, age and season, and the extent that [Cu], [Cd] and [Zn]s are reflected in [metallothionein (MT)]s. Although each [metal] and [MT] increased significantly with length, weight and age, those biotic variables explained <10% of the variation in each [metal] and only 11-16% for [MT]. Seasonal changes in [Cu] and [Cd] were paralleled by [MT]. The variation in [MT] explained by Cu (42%) was greater than by Zn (16%) and Cd (13%), and seasonally lay between 43 and 69% for those metals collectively. Thus, hepatic [MT] in eels is closely correlated with hepatic [heavy metal]s. However, the great variability among [MT]s for eels of similar sizes and ages, which reflects marked variability in hepatic [heavy metal]s, means that this variable reflects imprecisely the contamination level at a particular site. 相似文献
74.
Merja Otronen 《Behavioral ecology and sociobiology》1994,35(1):33-38
Male fertilisation success in relation to male size and the mating situation (ordinary pair formation with a single, nonvirgin female vs. take overs) was examined in the fly Dryomyza anilis. In ordinary matings, large males achieved higher fertilisation success than small ones when they were the second to mate with the female. Take overs differ from ordinary pair formation in that the second male experiences intensified sperm competition. This is because in take overs the female is not able to discharge any of the sperm inseminated by the first male as she usually does before a new mating. Compared with ordinary matings, take overs reduced the fertilisation success of the second male by 8–10%, whereas that of the first male was 7–14% higher in take overs. Even though the intruder was always larger than the paired male his superior fertilisation success did not compensate for the effect of the sperm already present in the female. In D. anilis, males can increase their fertilisation success by tapping the female's external genitalia with their claspers or having several copulation bouts per mating. Thus, in a take over, the intruder could respond to the intensified sperm competition by performing more tapping sequences per copulation bout or more copulation bouts per mating. In matings observed in the wild, males performed more tapping sequences after a take over than after pair formation with a single female, although the difference was not significant. The results show that there are differences in fertilisation success between males of different size. In addition, different mating situations can result in considerable variation in the fertilisation success of an individual male. Higher fertilisation success for the first male after a take over may be significant, in particular, for the reproductive success of small males, which frequently lose their females to large males. 相似文献
75.
Adjustment of parental effort in the puffin; the roles of adult body condition and chick size 总被引:6,自引:0,他引:6
K. E. Erikstad M. Asheim P. Fauchald L. Dahlhaug Torkild Tveraa P. Dahlhaug 《Behavioral ecology and sociobiology》1997,40(2):95-100
We examined the adjustment of parental effort of puffins by switching 20-day-old chicks randomly between parents of known
body condition. Among unmanipulated birds mass gain (5–20 days) and mass of 20-day-old chicks was positively correlated with
the body condition of parents at day 6. During the first 5 days after chick switching 28% (n = 55) of the parents deserted their foster chick. Parents which deserted their foster chick originally had a chick of their
own that was smaller than that of those which did not desert their foster chick. Whether parents deserted their foster chick
was also negatively related to the size of the foster chick. The mass of the foster chick was more important than the size
of the parents' own chick in determining the desertion rate of chicks. The mass gain of the foster chick during the first
5 days after switching was positively related to the body condition of foster parents and also positively related to the mass
of the foster parents' own chick, but negatively related to the size of the foster chick. The results suggest that puffins
adjust their parental effort according to both their own body condition and the size of the chick. The latter may indicate
the chick's prospect of survival and recruitment to the population.
Received: 20 January 1996 / Accepted after revision: 27 October 1996 相似文献
76.
Filippo Galimberti Simona Sanvito Chiara Braschi Luigi Boitani 《Behavioral ecology and sociobiology》2007,62(2):159-171
Reproductive effort is a key parameter of life history because it measures the resources allocated to reproduction at the
expense of growth and maintenance. Male reproductive effort always had a minor role with respect to female effort both in
the development of theories and in field research. Elephant seals are an ideal subject for reproductive effort studies because
they fast during the breeding season, splitting the phase of energy acquisition from the phase of energy use for breeding.
In this paper, we present results on male reproductive effort (weight loss estimated by photogrammetry) in southern elephant
seals (Mirounga leonina), the most dimorphic and polygynous of all mammal species. We show that total reproductive effort increases with age, with
no sign of late decrease or senescence. Male reproductive effort in this species depends mostly on behavioral factors, i.e.,
the success in competition with other males, and the intensity of interaction with females. A large effort results in large
gains in both mating success and fertilizations. The large reproductive success that a few males are able to achieve come
at a big cost in terms of energy expenditure, but this cost does not seem to affect the likelihood of survival to the following
breeding season. 相似文献
77.
Reproduction in birds requires the input of time and energy during discrete breeding phases leading to investment trade-offs
between laying date, clutch size, body mass, and incubation constancy. We investigated costs during incubation by experimentally
enlarging 25 clutches of white-tailed ptarmigan Lagopus leucurus. The experiment was conducted in 2 years, one with harsh weather that forced a natural delay in reproduction. When forced
to delay egg-laying, females began incubation with poorer body condition and foraged more during incubation. Rates of mass
loss during incubation were not affected by clutch enlargement, and did not differ between harsh and benign years; however,
females that were heavier at the start of incubation lost more mass than lighter females. Clutch-enlarged females had reduced
nest attendance compared to control birds in both years and incubation periods increased by up to 2 days relative to controls.
In the harsh year, there was a trend for clutch-enlarged females to have lower nest success, but there was no effect on overwinter
survival. Different behavioral responses by females in the 2 years showed that incubation costs may depend on other factors
such as female quality, food supply, or weather conditions. Incubation is a dynamic period during which birds may adjust energy
balances by varying body condition and food intake.
Received: 28 March 2000 / Received in revised form: 18 August 2000 / Accepted: 2 July 2000 相似文献
78.
Seven polybrominated diphenyl ethers (PBDEs) congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154 and BDE-183) and six indicator polychlorinated biphenyls (PCBs) congeners (CB-28, CB-52, CB-101, CB-138, CB-153 and CB-180) were measured in 24 pooled human milk samples comprised of 1237 individual samples from 12 provinces in China. The samples were taken to estimate the background body burden of general population and assess nursing infant exposure via human milk in China. The median concentrations of ∑7PBDEs and ∑6PCBs were 1.49 and 10.50 ng g−1 lipid weight (lw), respectively. BDE-28, BDE-47 and BDE-153 were predominant PBDE congeners accounting for nearly 70% of ∑7PBDEs. As for indicator PCBs, CB-153 was the most abundant congener, followed by CB-138. In our study, there was no significantly statistical relationship between concentrations of PBDEs in milk samples and maternal age as well as dietary habits. ∑7PBDEs did not correlate to ∑6PCBs in Chinese mothers’ milk. The human exposure to indicator PCBs in China was found to be significantly determined by maternal age, dietary habits and geographical factors. It is suggested that Chinese general population is probably exposed to PBDEs with multiple sources and pathways. The estimated daily intakes (EDI) of BDE-47, BDE-99 and BDE-153 for the Chinese nursing infant were much lower than corresponding threshold reference values suggested by USEPA. 相似文献
79.
de Boer WF Cao L Barter M Wang X Sun M van Oeveren H de Leeuw J Barzen J Prins HH 《Ambio》2011,40(1):68-77
We compared the European and eastern Chinese waterbird assemblages and checked whether the effects of human disturbance could
be detected in the assemblages’ composition. For the different Chinese provinces, we expected to find a negative effect of
economic development on the mean bird species mass and on the proportion of bentivorous, piscivorous and insectivorous bird
species. We also expected to find relatively fewer large species in the Chinese assemblage. Species rank–abundance curves
were relatively similar, but China had significantly more species with smaller body masses. The China assemblage was characterized
by relatively higher abundance of heavy-bodied species, contrary to our expectations. Mean bird body mass decreased in China
with increasing disturbance and increasing gross domestic product (GDP). For coastal provinces in China the percentage of
bentivorous, piscivorous and insectivorous bird species declined with increasing GDP, maybe through the increased use of pesticides
or fertilizer. 相似文献
80.