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1.
夏秋蚕病是北方蚕桑生产上存在的主要问题,对蚕桑的危害不断扩大。为此,笔者根据多年调查研究,试验摸索出了北方蚕区夏秋蚕病的防范对策。 相似文献
2.
北京在历史上曾发生多次重大水灾,给人民生命财产、城市建设及社会安定带来了巨大影响。形成水灾的主要因素是永定河决口泛溢和区域雨涝。现从大量的历史文献中列举几个实例,来看水灾的严重程度及其影响后果。 相似文献
3.
Qiang Li Tian Li Hongtao Chen Erwei Xiang Wenjuan Ruan 《Corporate Social Responsibility and Environmental Management》2019,26(1):248-256
This study examines whether executives justify their excess compensation through environmental information disclosure using a sample of listed companies in China's heavily polluting industries from 2010 to 2014. We find that executives' excess compensation is positively related to the quality of environmental information disclosure. The above relationship is significant in cases with strong demand for compensation justification (i.e., state‐owned enterprises and firms where an internal compensation gap is salient), indicating that executives manipulate environmental information disclosure about their companies according to their purposes. We also find that media pressure weakens the above relationship. A further test affirms a differential influence of media pressure in settings that involve public or private ownership, development of markets, and low or high product market competition. This study reveals a self‐serving motive of executives for environmental information disclosure. The findings of this study have practical implications for regulators, shareholders, and managers. 相似文献
4.
Settlement decisions in blue tits: difference in the use of social information according to age and individual success 总被引:1,自引:0,他引:1
Dispersers are expected to assess breeding habitat quality before settlement. Although cues reflecting habitat quality are
well studied, social cues have not been as well evaluated. In this paper, we studied breeding habitat selection during 3 years
in a natural population of blue tits, Cyanistes caeruleus, breeding in nest-boxes. Our aim was to investigate if this species used conspecific density and/or reproductive success
of con- and heterospecifics (i.e., social cues) in settlement decisions. The patterns observed were consistent with the idea
that juveniles, when dispersing from their natal patches, did not react to any of the cues that we tested. In contrast, breeders
that dispersed seemed to respond to both conspecific mean patch reproductive success (PRS) and breeding density of the settlement
patch in the year of dispersal, their response differing according to their own reproductive success. Indeed, failed breeders
moved to areas with high PRS and low density relative to source patches, while successful breeders behaved the opposite. The
comparison between juveniles and adults might be modulated by the limited time available to juveniles to gather information
on PRS and density at the end of the dispersing year. Adults lacking these time constraints, however, seemed to rely on these
conspecific cues although limited by their own quality. Additionally, breeders were more likely to be immigrants in patches
with relatively low breeding success and density the previous year, suggesting that settlement is influenced by multiple cues,
which may reveal information on different aspects of habitat and be available at different moments. Collectively, our results
support the importance of social cues for blue tits’ settlement. 相似文献
5.
简要统计了2016年7-8月国内发生的各种环境事件147起,包括沙尘天气2起,污染事件24起,地震41起,山体滑坡和泥石流32起,旱灾3起以及其他自然灾害45起. 相似文献
6.
7.
Yujie Pan Yalan Li Hongxia Peng Yiping Yang Min Zeng Yang Xie Yao Lu Hong Yuan 《Frontiers of Environmental Science & Engineering》2023,17(5):56
8.
Evolution from a solitary way of life to sociality involves changes in the modalities of within-population aggression. This
paper is concerned with environmental causes of variation in aggression within the complex of mole-rat species Spalax ehrenbergi. We focus on physiological constraints associated with aggressive behaviour, i.e. those resulting from emotional arousal
and thus stress. Aggression, social stress sensitivity and urine osmolarity were studied in males of two chromosomal species
of Spalax ehrenbergi, 2n = 52 (occurring in cool humid areas) and 2n = 60 (occurring in warm arid zones). Males with 2n = 52 reached a higher level of within-population aggression during a 3-round tournament (an average, 488 ± 140 acts) than
males with 2n = 60 (163 ± 54 acts). The species with 2n = 52 displayed a higher corticosterone response after a social encounter (in average, 5.15 ± 0.54 μg/100 ml) than that with
2n = 60 (3.0 ± 0.3 μg/100 ml) whereas resting levels of this hormone were low and not different between the two species. Urine
osmolarity was significantly higher in males with 2n = 60 (331.9 ± 18.6 mmol/kg) than males with 2n = 52 (267.3 ± 10.9 mmol/kg). Considering the overall general trend urine osmolarity tended to be negatively related to the
level of aggression, while corticosterone levels tended to vary positively with aggressiveness (Fig. 3). Our results allow
further discussion of the hypothesis that high levels of aggression could be selected against in arid habitats due to their
physiological correlates (decrease in water economy, increased corticosterone leading to potential energy mobilisation and
loss). We propose that behavioural ecophysiology could have contributed to the radiation of the S. ehrenbergi superspecies into increasingly arid environments, and may favour evolution toward social tolerance.
Received: 10 June 1995/Accepted after revision: 25 October 1995 相似文献
9.
Several factors thought to be important for the evolution of cooperative breeding in vertebrates have received little attention
in facultatively social insects. One of these, the “habitat saturation hypothesis” of Selander (1964), predicts that colony
sizes will be greater in breeding units where dispersal opportunities are limited, suggesting that group living is a secondary
option to independent reproduction. The Australian allodapine bee Exoneura bicolor exhibits a number of traits that occur in cooperatively breeding bird species, including long life-span, repeated opportunities
for reproduction, and vulnerability to brood predation and parasitism. We experimentally examined the effect of a potentially
limiting environmental factor, nesting substrate availability, as an agent influencing sociality in E. bicolor. We manipulated nesting substrate availability in two separate locations during a time when foundress dispersal is common.
No significant difference was found between colony sizes in cases where dispersal options were abundant and cases where dispersal
options were limited. An increase in opportunities for dispersal did not lead to higher rates of independent nesting, suggesting
that cooperative nesting is a preferred strategy regardless of distance-related costs of dispersal. Reproductivity per female
and brood survival were examined as factors selecting for group living. Low survival of brood in single-female nests has the
potential to select for cooperative nesting in this bee.
Received: 29 September 1995/Accepted after revision: 24 June 1996 相似文献
10.
Yu Qingkang 《Disasters》1982,6(3):202-206
This paper describes the necessity and the possibilities for mitigating the effects of natural disasters as exemplified by the Chinese experiences in Tangshan and Sichuan etc. With the dynamic viewpoint as a guiding concept the paper advocates the “prevention first” policy as well as planning strategies for human settlements in disaster-prone areas. It covers emergency and reconstruction planning as well as recommendations for prevention and mitigation planning. The paper also reviews the Chinese experience. 相似文献