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101.
在结合参考1990年以来三明全市名木古树调查、各自然保护区植被调查的基础上,对1999年至2001年全市各县区珍稀野生植物资源调查资料进行市级汇总,得出52个目的物种资源调查结果,并通过分析评价其资源现状,提出结论与建议。 相似文献
102.
103.
贮木场选址模型的研究 总被引:1,自引:0,他引:1
建立了一个贮木场选址的数学模型,这个模型将动态经济评价方法,运输网络和贮木场选址有机地结合起来。 相似文献
104.
105.
Gammon DW 《Pest management science》2007,63(7):625-627
West Nile virus is becoming increasingly prevalent in the USA, causing fever, encephalitis, meningitis and many fatalities. Spread of the disease is reduced by controlling the mosquito vectors by a variety of means, including the use of pyrethroid insecticides, which are currently under scrutiny for potential carcinogenic effects in humans. Pyrethrins and resmethrin, a pyrethroid, have been shown to cause tumours in rat and mouse models respectively. However, the tumours appear to be caused by liver enzyme induction and hypertrophy rather than genotoxicity, and the results are therefore unlikely to be applicable to humans. Nonetheless, for resmethrin, the US Environmental Protection Agency (EPA) has concluded that there is a likely risk of carcinogenicity in humans, requiring the manufacturers to provide more detailed data to prove that it can be used safely in vector control. Reproductive toxicity of resmethrin in the rat is also discussed. 相似文献
106.
Jane C.F. Chang Paul Ciaccio Patricia Schroeder Lindsay Wright Russell Westwood Anna-Lena Berg 《Journal of toxicologic pathology》2014,27(1):31-42
AZD3783, a cationic amphiphilic drug and a potent inhibitor of the 5-hydroxytryptamine
(5-HT1B) receptor, was explored as a potential treatment for depression. To
support clinical trials, repeat dose toxicity studies in rats and dogs were conducted.
Here we report toxicity findings in dogs after dosing from 1 to 3 months. In the 1-month
study, there were minimal neuronal vacuolation in the brain, a marked increase in liver
enzymes accompanied by hepatocellular degeneration/necrosis and phospholipidosis (PLD),
and PLD/cholecystitis in the gallbladder of animals dosed at 47 mg/kg/day. In the 3-month
study, neurotoxicity resulted in euthanasia of one animal dosed at 30 mg/kg/day after 86
days. Extensive pathologic changes were seen in all animals in retina epithelium
(inclusion bodies), brain (neuronal vacuolation, degeneration, or necrosis and nerve fiber
degeneration), spinal ganglia (vacuolation, degeneration, or necrosis), as well as sciatic
and optic nerves (degeneration). Pigment-laden macrophages were observed in the lung,
kidney, liver, gallbladder, bone marrow, gastrointestinal tract, and lymphoid tissues.
Also seen were vitrel and retinal hemorrhage in the eyes. A brain concentration and
pathology study showed that the concentration of AZD3783 in the brain was approximately 4
times higher than in the plasma after 4 weeks of dosing, however, they were similar in all
regions examined, and did not correlate with areas with pathologic findings. Our findings
with AZD3783 in dogs have not been reported previously with other CNS compounds that
effect through serotonergic pharmacology. 相似文献
107.
舟山渔场人工鱼礁投放海域生态环境前期评估 总被引:18,自引:0,他引:18
根据2002年6-7月在舟山渔场朱家尖外侧开展人工鱼礁投放海域本底调查所获的海洋生物和海洋水文环境资料及以往有关文献中对该海域的调查资料,对朱家尖外侧拟投人工鱼礁海域的海水理化因子和海洋生物种类组成、数量分布和群落结构特征作了较详细的分析研究,以评估该海域是否适于投放人工鱼礁.结果得知:该海域底质为粉砂质粘土,浮游生物种类和数量及底栖生物种类和数量较多,水深为14~19m,温、盐度季节变化明显、透明度较高、水色相对较清,水质绝大多数指标符合国家一、二类水质标准,海域适合沿岸岛礁性鱼类如石斑鱼、褐菖、鲈鱼等的栖息生长,历史上渔业资源丰富,也无工厂废水排放,不会对海洋生态环境产生重大污染,因此,可以为良好的投放人工礁之场所. 相似文献
108.
Darpa Saurav Jyethi P.S. Khillare Sayantan Sarkar 《Urban Forestry & Urban Greening》2014,13(4):854-860
This study reports, for the first time, the profiles and source analysis of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) associated with PM10 (particulate matter with aerodynamic diameter ≤10 μm) at a protected and ecologically sensitive area – the Yamuna Biodiversity Park – located in the megacity Delhi, India. Weekly PM10 sampling was carried out at this location for 1 year (2009–2010) and the annual mean PM10 level was found to be ~9 times the World Health Organization limit. Seasonal variation of PAHs (range 37.2–74.0 ng m?3) was significant with winter values being 72% and 68% higher than summer and monsoon respectively. Principal component analysis coupled with multiple linear regression identified diesel, natural gas and lubricating oil combustion (49.5%), wood combustion (25.4%), gasoline (15.5%) and coal combustion (9.6%) sources for the observed PAHs. Heavy traffic on the national highway and arterial roads and domestic emissions from suburban households in the vicinity of the park appeared to have significantly affected its air quality. A substantial portion (~55%) of the aerosol PAH load was comprised of carcinogenic species, which yielded a considerably high lifetime inhalation cancer risk estimate (8.7E?04). If considered as a conservative lower-bound estimate, this risk translates into ~211 excess cancer cases for lifetime inhalation exposure to the observed PAH concentrations in Delhi. 相似文献
109.
Habitat destruction is one of the main threats to environmental integrity. Assessing the consequences of human impacts is crucial both to predict and prevent structural and functional changes of habitats. However, to date almost all studies on marine threats, from regional to global scales, have been entirely qualitative and generally based on little more than expert opinion. We have developed a meta-analytical approach to quantify overall effects of various stressors on different Mediterranean habitat types and to compare the relative importance of different impacts across a range of habitats. We first qualitatively reviewed and synthesized 366 experiments (either manipulative or correlative) collected in the literature. After a selection procedure, we finally quantitatively meta-analyzed 158 experiments. We showed that fisheries (destructive or not), species invasion, aquaculture, sedimentation increase, water degradation and urbanization have negative effects on Mediterranean habitats and associated species assemblages. We also explored the overlap between the impacts identified as important in the Mediterranean and those identified by experts as being important globally, highlighting the inadequacies of relying on expert opinion alone. Finally, we drew attention to the critical lack of empirical knowledge about marine systems in many areas of the Mediterranean, which impedes the implementation of effective conservation measures. Our study is the first to synthesize experimental analyses on human-driven impacts on marine habitats across such a broad geographic scale. 相似文献
110.
基于共生理论构建托管农户与托管服务组织两主体共生演化Lokta-Volterra动态模型,探讨不同共生系数下两主体共生演化的均衡结果,并在此基础上利用数值仿真模拟两主体共生演化模式。研究表明:托管农户与托管服务组织在不同共生环境下会形成寄生共生、偏利共生和互惠共生三种共生模式,且三种模式具有动态演化的特征;托管农户与托管服务组织共生演化的均衡结果取决于二者间的共生系数;托管农户与托管服务组织在互惠共生模式下才能达到最优的发展状态。最后,基于模型结果提出相应的政策建议。 相似文献