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991.
汉江流域秦巴山区中药材资源优势与持续发展 总被引:1,自引:0,他引:1
郑远昌 《长江流域资源与环境》1997,6(4):329-333
汉江流域秦巴山区生态环境复杂,生物多样性突出,中药材资源丰富,具有很大优势,主要表现在:种类多;产量大;多名优特种类。中药材生产对山区经济发展起重要作用。中药材生产持 拟采取下列措施或途径;建设专门化生产基地;进行综合性经营;加强对野生资源保护性利用;加强科研工作。 相似文献
992.
The influence of storage on the morphology and physiology of phthalic acid-degrading aerobic granules 总被引:1,自引:0,他引:1
The precultured aerobic granules with special degradabilities could be used as a feasible bioseed for enhancement of aerobic granulation systems. In practice, the storage stability, physicochemical characteristics, and recovering efficiency of granules are crucial for a long-distance transportation and successful application. In this study, phthalic acid (PA)-degrading aerobic granules were cultivated and stored for 8 wk at 4 °C. The granular size, settling ability as well as structure integrity was found stable during the storage period. It was observed that the upper 1/3 part of granules stored in the reagent bottle turned to black color, while the lower 2/3 part granules did not significantly change color (brown–yellow) after the 8-wk storage. The black and brown–yellow color PA-degrading granules were manually separated and re-inoculated into two identical sequencing batch reactors for reviving the PA degradation capability. After a 7 d operation, both black and yellow granules restored their activities to the levels before storage, in terms of total organic carbon removal efficiency (100%), specific oxygen uptake rate (59 mg g VSS−1 h−1), and adenosine triphosphate content (0.016 mg g VSS−1). This study demonstrated that aerobic granules grown on a complex substrate could tolerate storage conditions and rapidly restored their bioactivities toward the target pollutant. The results also shed the light on the future application of precultured aerobic granules with unique functions for biodegradation and bioremediation purpose. 相似文献
993.
自然资源代际转移模型研究 总被引:4,自引:2,他引:2
代际均衡发展是可持续发展的核心内容之一,而代际均衡的实现在目前情况下有赖于代际主动财富转移改策实施。政府的宏观调控是实施这一政策的有力手段。具体的措施可开征“资源代际补偿税”以建立专项基金制度 相似文献
994.
本文以玉山县宅前小流域开发治理规划为例,指出红壤地区小流域治理指导思想和应遵循原则,提出以山顶及坡度≥25°山坡营造防护林,坡度<25°山坡实行等高开垦为水土保持措施;同时兴修水利,建立山地灌溉体系,努力提高劳动者素质,加速区域经济发展,此小流域开发治理将为我国南方未开发的红壤地区充分利用自然资源提出一个典范。 相似文献
995.
The adsorption/desorption behavior of copper and cadmium on soils was investigated in this study. The adsorption isotherm of copper and cadmium conformed to Langmuir equation better than Freundlich equation. The effect of ionic strength, pH, and organic acid, including ethylenediamine tetraacetic disodium acid salt (EDTA), citric acid, oxalic acid and tartaric acid, on the desorption of copper and cadmium was studied. The desorption of copper and cadmium increased with the increase of ionic strength, while the desorption decreased with the rise of pH. The desorption of copper and cadmium enhanced by organic acids was influenced by pH. EDTA showed excellent enhancement on the desorption of both copper and cadmium; citric acid demonstrated great enhancement on the desorption of copper but negligible enhancement on the desorption of cadmium; oxalic acid enhanced the desorption of copper only at pH around 6.4 and enhanced the desorption of cadmium in the pH range from 6.4 to 10.7; tartaric acid slightly enhanced the desorption of copper but negligibly enhanced the desorption of cadmium. The desorption mechanism in the presence of organic acids were explained as the competition of complexation, adsorption and precipitation. The net effect determined the desorption efficiency. This study provided guidance for the selection of organic acids to enhance the electrokinetic (EK) remediation of copper and cadmium from contaminated soils. 相似文献
996.
生态旅游的非持续特征 总被引:7,自引:0,他引:7
生态旅游是以生物多样性和文化多样性作为资源的,生物多样性常常十分脆弱,文化多样性则具有明显的不可复制性,因此生态旅游在经济、社会、文化方面都表现出潜在的非持椟特征。生态旅游必须要在开发利用生物多样性和文化多样性资源的同时,考虑这些资源的保护以做到可持续利用,从而获得最大的社会、经济和环境效益。 相似文献
997.
998.
Because of its cost and time saving features, solid-phase microextraction (SPME) is a leading candidate as a biomimic technique in assessing the bioavailable fraction of hydrophobic organic contaminants (HOCs) in sediment porewater. However, no predictive modeling framework in which to systematically address the effect of key parameters on SPME performance for this application exists. In this study, we derived two governing equations to predict (1) the minimum sediment volume (V(s)min) required to achieve non-depletive conditions, and (2) dissolved phase HOC porewater concentrations (C(pw)) as functions of HOC- and sediment specific characteristics in a conceptual three compartment system. The resulting model predicted that V(s)min was independent of HOC concentrations both in sediment and porewater, but did vary with hydrophobicity (characterized by logK(ow)), the fraction of sediment porewater (f(pw)), and the volume (V(f)) of the SPME sorbent phase. Moreover, the effects of these parameters were minimized (i.e., V(s)min reached plateaus) as logK(ow) approached 4-5. Model predictions of C(pw), a surrogate for SPME-based detection limits in porewater, decreased with increasing sediment volume (V(s)) at low V(s) values, but rapidly leveled off as V(s) increased. A third result suggested that the sediment HOC concentration required for SPME is completely independent of K(ow). These results suggest that relatively small sediment volumes participate in exchange equilibria among sediment, porewater and the SPME fiber, and that large sediment HOC reservoirs are not needed to improve the detection sensitivity of SPME-based porewater samplers. The ultimate utility of this modeling framework will be to assist future experimental designs and help predict in situ bioavailability of sediment-associated HOCs. 相似文献
999.
应用模式识别法研究芳腈化合物结构与活性的关系 总被引:2,自引:0,他引:2
基于23个芳腈衍生物对发光菌的毒性疚和一批结构参数,用模式识别法研究了结构与活性的关系。在化合物的生物活性类别与模式特征之间建立的3个类别判别函数对化合物活性类别的判别正确率达91.3%,并为进一步的研究工作合理地挑选了4个代表性化合物。 相似文献
1000.
Gini Index for Cities: A Preliminary Study on Regional Differences of Chinese City Size Distribution
Liu Wangbao & Zheng Bohong Department of Architecture Urban Planing Central South University Changsha Hunan 《中国人口.资源与环境(英文版)》2004,2(4)
City size distribution is of interest because of a number of key stylized facts, including notably Zipf's law for cities and the importance of urban primacy. But a new and more efficient method Gini index can be used for calculating regional city size distribution. This paper begins by developing a calculation method for the Gini index, dividing the whole country into 26 areas and then calculating each area's Gini index value. Based on these calculation results, this paper gives a preliminary study on regional differences of its city size distribution and the dynamics. 相似文献