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991.
关于害虫生态防治若干概念的讨论   总被引:19,自引:0,他引:19  
讨论有关害虫生态防治策略的若干基本概念,包括产生背景,含义,与综合防治等的关系以及实施等。综合防治遇到的一些问题使得人们寻找新的策略,而生态学,计算机,信息科学及分子生物学的知识与技术的普及则催产了生态防治策略。该策略的要义是强调系统观点和经济生态学原则,运用任何适宜的措施调控害虫种群,不断改善农业生态系统功能,实现环境安全,经济高效,生态协调,持续发展的目标,生态防治的定义与综合防治十分接近,实践中难以区分。生态防治策略及措施具有不同的发展阶段,且随国家和地区的条件不同而变化。与综合防治一样,生态防治的实施需要适宜的社会组织,包含社会组织的统一防治2将有助于生态防治的实施。  相似文献   
992.
土壤-作物污染物迁移分配与食物安全的评价模型及其应用   总被引:35,自引:4,他引:31  
人类对潜在有毒污染物的接触及其健康风险是当今环境科学与医学共同关心的热点问题,而污染土壤中毒污染物在土壤-植物系统迁移与转化是其中的关键基础问题,本文基于对现有资料的分析,提出计算污染物的环境控制标准的数学模型-污染生态模型和环境化学模型,模型计算结果表明,未污染条件下的土壤-植物间元素分配参数不符合污染土壤环境中的土壤-食用作物-人类间污染物分配的特点。因此,制定土壤环境控制标准必须考虑实施土壤的环境化学特点,本文建立的模型有其对污染物的土壤环境控制标准的计算结果,期望于对我国加强污染生态研究和食物安全评价有一定的参考意义。  相似文献   
993.
177例双瓣替换术的心肌保护和辅助循环的探讨   总被引:1,自引:0,他引:1  
目的:本文报告了177例双瓣替换术的心肌保护和辅助循环方法。临床9资料:本组病例包括165例主动脉和二尖瓣替换术,8例同时行三尖瓣成形术;4例同时行冠状动脉搭桥术。术前心功能Ⅲ-Ⅳ级,心胸心率54-89%,结果:升主动脉阻断时间48-265分。自动复跳114例,9例作IABP辅助,IAPP时间6-162小时,7例成活,成功率为78%,全组177例住院死亡6例,占死亡3.40%,结论:在体外循环中采用综合的心肌保护和辅助循环的方法的手术成功的关键。  相似文献   
994.
中国湿地简述   总被引:8,自引:0,他引:8  
燕艳 《生物学杂志》2002,18(6):59-60
对中国湿地的分布、主要类型、湿地的资源特点、生态特点以及湿地在环境保护、调节气候、物质生产等方面作了简要阐述,并简要分析了中国湿地的保护现状,对湿地的保护提出了几点建议。  相似文献   
995.
A blend of eight nonhost angiosperm volatiles (benzyl alcohol, benzaldehyde, guaiacol, nonanal, salicylaldehyde, (E)‐2‐hexenal, (E)‐2‐hexen‐1‐ol and (Z)‐2‐hexen‐1‐ol) without [NAV] and with [NAVV] (–)‐verbenone (4,6,6‐trimethylbicyclo[3.1.1]hept‐3‐en‐2‐one) were tested at low (L), medium (M) and high (H) release rates for their ability to reduce attraction of western pine beetle, Dendroctonus brevicomis LeConte, to attractant‐baited (exo‐brevicomin [racemic, 3 mg/d], frontalin [racemic, 3 mg/d] and myrcene [18 mg/d]) multiple funnel traps. NAV‐L (40 mg/d) had no significant effect. Verbenone alone (50 mg/d) and NAV‐M (240 mg/d) both significantly reduced attraction, but no significant difference was observed between the two treatment means. NAV‐H (430 mg/d) significantly reduced catches by ~60% and 78% compared to verbenone alone and the baited control, respectively. In a second experiment, combining (–)‐verbenone with NAV (NAVV) increased the effects observed in Experiment 1. NAVV‐M (240 mg/d) resulted in an ~69% and 83% reduction in trap catch compared to verbenone alone and the baited control, respectively. Significantly fewer D. brevicomis were captured in NAVV‐H (430 mg/d) than any other treatment resulting in an ~93% reduction in trap catch compared to the baited control. In a third experiment, NAVV was tested at three release rates for its ability to protect individual ponderosa pines, Pinus ponderosa Dougl. ex Laws., from attack by D. brevicomis. Cumulative release rates varied in direct proportion to tree diameter, but represented quarter, half and full NAVV rates. NAVV significantly reduced the density of D. brevicomis attacks, D. brevicomis successful attacks, and levels of tree mortality on attractant‐baited trees. Only three of 15 NAVV‐treated trees died from D. brevicomis attack while ~93% mortality (14/15) was observed in the untreated, baited control. Quarter and half rates were ineffective for reducing tree mortality.  相似文献   
996.
芡实的营养保健价值及其加工利用   总被引:4,自引:0,他引:4  
芡实是一种珍贵的药食兼用的水生经济作物种子,具有很高的营养价值和多种保健功能。着重介绍了国内外对芡实的营养组分、药用价值及其功能成分的研究进展,并对其在国内的加工利用现状和前景进行了分析和展望。  相似文献   
997.
As there is limited information on the mechanisms of vegetative desiccation tolerance in pteridophytes, we undertook a comprehensive anatomical, ultrastructural, physiological and biochemical study on the fern Mohria caffrorum . Our data show that this species is desiccation-tolerant during the dry season, and desiccation-sensitive in the rainy season. This system allows the verification of protection mechanisms by comparison of tolerant and sensitive tissues of the same species at the same developmental age. Tolerant fronds acquire protection mechanisms during drying that are mostly similar to those reported for angiosperms. These include: (i) chlorophyll masking by abaxial scales and frond curling; (ii) increased antioxidant capacity that is maintained in dry tissues; (iii) mechanical stabilization of vacuoles in the dry state; (iv) de novo production of heat stable proteins (at least one identified as a putative chaperonin); (v) accummulation of protective carbohydrates (sucrose, raffinose family oligosaccharides and cyclitols). This study has implications for the biotechnological production of drought-tolerant crops, and allows speculation on the evolution of vegetative desiccation tolerance.  相似文献   
998.
三江自然保护区湿地保护与退耕还湿政策的农民响应   总被引:8,自引:0,他引:8  
通过对三江自然保护区核心区边缘6个村屯和实验区内5个村屯的310家农户家庭就湿地保护与退耕还湿的问卷调查和访谈研究,探讨了农民对湿地保护和退耕还湿政策的响应.调查发现:湿地保护与退耕还湿的农民响应具有很大的相似性,不同年龄结构,认知水平和区域位置,决定了他们对湿地保护和退耕还湿支持意愿的不同,表现在年轻人、受教育程度高和居住在实验区的人更倾向于湿地保护和退耕还湿.在退耕还湿问题上,农民反对退耕还湿的原因和农民接受退耕还湿的补偿方式选择都反映出农民对现有耕地及补偿制度的思考.研究表明:湿地重要性已经被广大农民所认可,农民对湿地保护和退耕还湿政策的支持主要取决于能否保证农民的经济利益;缺乏明确的退耕还湿补偿制度和替代生计引导是湿地保护和退耕还湿实施的制度障碍和政策缺失.  相似文献   
999.
Coastal vegetation has been widely recognized as a natural method to reduce the energy of tsunami waves. However, a vegetation barrier cannot completely stop a tsunami, and its effectiveness depends on the magnitude of the tsunami as well as the structure of the vegetation. For coastal rehabilitation, optimal planning of natural coastal systems, and their maintenance, we need to quantitatively elucidate the capacity of vegetation to reduce the energy of tsunami waves. The limitations of coastal forests in relation to the magnitude of a tsunami and the maintenance of forests as natural disaster buffer zones have to be understood correctly for effective coastal vegetation planning. Demerits of coastal forests have also been revealed: for example, an open gap in a forest (i.e., a road, river, difference in elevation, etc.) can channel and amplify a strong current by forcing it into the gap. Floating debris from broken trees also can damage surrounding buildings and hurt people. However, many studies have revealed that these demerits can be overcome with proper planning and management of mangroves and coastal forests, and that coastal vegetation has a significant potential to mitigate damage in constructed areas and save human lives by acting as buffer zones during extreme natural events. However, mangrove forests have been damaged by anthropogenic activities (i.e., tourism, shrimp farming, and industrial development), making coastal areas increasingly vulnerable to tsunamis and other natural disasters. The effectiveness of vegetation also changes with the age and structure of the forest. This highlights the fact that proper planning and management of vegetation are required to maintain the tsunami buffering function of coastal forests. Although many government and nongovernmental organizations have implemented coastal vegetation projects, many of them have been unsuccessful due to a lack of proper maintenance. A pilot project in Matara City, Sri Lanka, revealed that participation and support from local authorities and communities is essential to make the planting projects successful. An integrated coastal vegetation management system that includes utilization of the materials produced by the forest and a community participation and awareness program are proposed to achieve a sustainable and long-lasting vegetation bioshield.  相似文献   
1000.
近年来山东乳山茶业逐渐兴起, 但由于北方冬春季温度低和倒春寒频繁发生, 茶叶种植面积逐年减小。如何在低成本管理的基础上提高茶叶产量和品质, 成为乳山茶园管理的一大难题。以2007年春季采用水平梯田整地种植的茶园为试验区, 以梯田周围营造的4种网格(8 m × 80 m, 12 m × 80 m, 20 m × 80 m, 40 m × 80 m)茶园防护林为研究对象, 分别在2013年4月、8月和12月, 测定风速、空气温度、土壤温度、空气相对湿度及土壤相对湿度, 以纯茶园作为对照, 进行了小气候因子测定和分析。结果表明: (1) 4种防护林均能有效地降低茶园内风速, 调节气温、土壤温度和土壤相对湿度, 增加空气相对湿度, 为茶树生长提供适宜的生态环境; (2)由于区域水分通量和太阳辐射的季节变化, 4种防护林的小气候调节效应也表现出一定的季节性差异; (3)主成分分析结果表明, 4种茶园防护林中, 影响小气候因子的主要因素是气温和土壤温度, 其因子负荷量分别为-0.978和0.986, 但风速与气温呈极显著相关关系, 与土壤温度之间无显著线性关系, 因此, 风速也能间接地影响林内小气候; (4) 8 m × 80 m的防护林对小气候的总体调节效应优于其他3种防护林。  相似文献   
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