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1.
生物多样性的经济价值   总被引:21,自引:2,他引:19  
生物多样性的总经济价值包含了它的可利用价值(use value, UV)和非利用价值(non-use values, NUV)。可利用价值可以被进一步分成直接利用价值(direct use values, DUV),间接利用价值(indirect use values, IUV)和可选择价值(option values, OV),即可能的利用价值。非利用价值主要是存在价值(existence values, EV)。生物多样性所提供的使用价值常常不能就地实现,而可能会通过某种通道,在空间上的流动,到达一个具备适当外部条件的地区,实现其使用价值。我们称这种现象为生物多样性价值在空间上的流动。  相似文献   

2.
Compared to the association between cigarette smoking and psychiatric disorders, relatively little is known about the relationship between smokeless tobacco use and psychiatric disorders. To identify the psychiatric correlates of smokeless tobacco use, the analysis used a national representative sample from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) wave 1. Smokeless tobacco use was classified as exclusive snuff use, exclusive chewing tobacco, and dual use of both snuff and chewing tobacco at some time in the smokeless tobacco user''s life. Lifetime psychiatric disorders were obtained via structured diagnostic interviews. The results show that the prevalence of lifetime exclusive snuff use, exclusive chewing tobacco, and dual use of both snuff and chewing tobacco was 2.16%, 2.52%, and 2.79%, respectively. After controlling for sociodemographic variables and cigarette smoking, the odds of exclusive chewing tobacco in persons with panic disorder and specific phobia were 1.53 and 1.41 times the odds in persons without those disorders, respectively. The odds of exclusive snuff use, exclusive chewing tobacco, and dual use of both products for individuals with alcohol use disorder were 1.97, 2.01, and 2.99 times the odds for those without alcohol use disorder, respectively. Respondents with cannabis use disorder were 1.44 times more likely to use snuff exclusively than those without cannabis use disorder. Respondents with inhalant/solvent use disorder were associated with 3.33 times the odds of exclusive chewing tobacco. In conclusion, this study highlights the specific links of anxiety disorder, alcohol, cannabis, and inhalant/solvent use disorders with different types of smokeless tobacco use.  相似文献   

3.
目的:了解并评价社区卫生服务机构基本药物合理使用情况,为基层基本药物合理用药提供参考意见。方法:对社区卫生服务机构进行抽样调查,通过对处方进行抽样和对医生进行抽样问卷调查,根据医疗机构合理用药评价指标对处方基本药物使用情况进行评价,并分析可能导致不合理用药的相关因素。结果:单张处方平均使用药品数为:城区(4.9±1.2)个,农村(213±0.7)个;每100张处方抗生素使用比例:城区78.9%,农村57.3%,其中两联使用比例分别为20.1%和32.4%;人均药费:城区为(36.9±5.2)元,农村为(21.3±4.7)元;参加合理用药培训的医生所开处方药品合理使用的比率是98.0%,而未参加过培训的医生合理用药的比率是77.1%,经卡方检验,差异有统计学意义,P〈0.05。结论:社区卫生服务机构存在一定的基本药物使用不合理现象,对医生加强基本药物合理使用的培训可以提高基本药物合理使用率。  相似文献   

4.
使用工具曾被认为是人类独有的能力,然而,在过去的50年中,学界逐渐认识到工具的使用普遍存在于整个动物界。其中,使用工具最多的类群是哺乳类、鸟类和昆虫。动物使用工具有一定目标性,然而大多数动物仅考虑当前的目标,而非长远目标。动物使用工具的行为受到环境因素和动物自身认知能力、生理特点与进化历史的影响,并可能表现出一定的个体差异。有些动物使用工具的行为是与生俱来的,然而大部分高等动物通过试错学习获得使用工具的能力。通过模仿学习,一些使用工具的行为可以传播和演化,从而在种群中广泛分布。工具的使用是动物认知领域的核心概念之一,开展动物使用工具的研究,能够加深对动物认知能力和行为进化的理解。  相似文献   

5.
基于地形梯度的岩溶槽谷区土地利用空间格局分析   总被引:5,自引:0,他引:5  
王权  李阳兵  刘亚香  胡先培 《生态学报》2019,39(21):7866-7880
揭示当前多因素驱动机制下岩溶槽谷区典型地貌单元在地形梯度上土地利用分布的一般规律与差异性特征具有重要意义。以2017年landsat TM高清影像和30 m×30 m DEM(Digital Elevation Model)为数据源,并结合实地调查,通过地形位分布指数、土地利用多样性指数、土地利用程度指数及土地利用相对合理性指数指标计算,探讨岩溶槽谷区地形梯度的土地利用类型空间分布共同特征与差异。结果表明:(1)岩溶槽谷区土地利用类型呈现山坡(高地形位)-槽坝(低地形位)两种分布格局特色存在,且土地利用类型在地形梯度上主要以低、中、高3种地形位组合模式;(2)土地利用类型在地形梯度上呈现梯度效应,表现出各自分布特征与差异;(3)岩溶槽谷区土地利用多样性、土地利用程度和土地利用合理性在地形梯度上分布格局既存在一些共同性特征,又存在各自差异性;(4)地形梯度土地利用特征差异性是受自然因素、社会经济因素、政策因素共同作用的结果。  相似文献   

6.
Inhalant use is especially prevalent among antisocial youth and can have serious health consequences. However, the extant literature has not investigated how use of various inhalants may co-occur among incarcerated youth. This study begins to address this gap in the literature by using latent class analyses to form distinct typologies of inhalant use. Study participants were residents (N = 723) of 27 Missouri Division of Youth Services facilities. Interviews assessed psychiatric symptoms, antisocial traits, delinquency, trauma, suicidality, and substance use behaviors. The mean age of the mostly male, ethnically diverse sample was 15.5 (S.D. = 1.2) years old. The study revealed the following classes of inhalant use: (1) severe polyinhalant use; (2) moderate polyinhalant use; (3) gas and permanent marker use; and (4) low-use. Compared to the low-use class, members of the severe polyinhalant use class had experienced more than double the rate of head injuries, the highest rates of traumatic experiences, and the highest rates of mental illness diagnoses. The gas and markers class had the highest rate of reporting hearing voices, followed by the severe polyinhalant use class, and the moderate polyinhalant use class. Results of this study underscore the need to address the high rate of head injuries and mental health diagnoses that contribute to severe polyinhalant use.  相似文献   

7.
以武夷山不同海拔(600、900、1300、1500、1800、2000和2100 m)的乔木、灌木和草本3种生活型植物为研究对象,观测其水分利用效率和叶片氮、磷养分浓度随海拔的变化趋势,旨在探索海拔梯度间水分、养分变化与植物水分利用效率变化的关系.结果表明: 植物水分利用效率随海拔的增加呈显著上升趋势,乔木叶片δ18O随海拔变化不显著.总体上看,叶片氮浓度未观测到规律性的变化,高海拔地区的叶片磷浓度显著高于低海拔地区.水分利用效率与叶片磷浓度呈显著正相关,而与叶片氮浓度相关性不显著.不同海拔植物水分利用效率变化主要由光合速率的变化引起,水分状况对植物水分利用效率的影响不显著.海拔梯度间植物叶片磷浓度的差异对光合速率影响显著,进而影响水分利用效率.  相似文献   

8.
Impulsive behaviors are closely linked to drug use and abuse, both as contributors to use and as consequences of use. Trait impulsivity is an important determinant of drug use during development, and in adults momentary 'state' increases in impulsive behavior may increase the likelihood of drug use, especially in individuals attempting to abstain. Conversely, acute and chronic effects of drug use may increase impulsive behaviors, which may in turn facilitate further drug use. However, these effects depend on the behavioral measure used to assess impulsivity. This article reviews data from controlled studies investigating different measures of impulsive behaviors, including delay discounting, behavioral inhibition and a newly proposed measure of inattention. Our findings support the hypothesis that drugs of abuse alter performance across independent behavioral measures of impulsivity. The findings lay the groundwork for studying the cognitive and neurobiological substrates of impulsivity, and for future studies on the role of impulsive behavior as both facilitator and a result of drug use.  相似文献   

9.
深圳市土地利用变化对流域径流的影响   总被引:114,自引:3,他引:111  
史培军  袁艺  陈晋 《生态学报》2001,21(7):1041-1049
土地利用所引起的流域下垫面变化严重影响着洪涝灾害的致灾过程,以深圳市为例,探讨下垫面条件对流域径流过程的影响,应用美国农业部水土保持局(Soil Conservation Service)研制的小流域设计洪水模型-SCS模型对深圳市部分流域进行了径流过程的模拟,重点分析 了土地利用方式、土壤类型、前期土壤湿润程度等下垫面因素以及降雨因素对降雨-径流关系的影响。结果表明,随着人类活动的加剧,土地利用的变化使径流量趋于增大;降雨强度越大、前期土壤湿润程度而发生变化,CN值(Curve Number)的高值区主要集中在城市用地和水体;低值区主要出现在林地、灌草地、果园等植被覆盖较好,地势起伏较大的地区。  相似文献   

10.
Perceptions of family alcohol use have been linked to adolescent alcohol use behaviors, yet there have been no studies that have assessed this relationship in young adults. This study examined perceptions of family alcohol use and their association with participants’ self-reported alcohol use. Participants included 171 undergraduate students (mean age = 21.67, 71.9 percent female, 75.4 percent Caucasian). Participants completed measures assessing quantity and frequency of alcohol use, negative consequences of use, and sibling relationship quality. They also reported their perceptions of alcohol use for siblings and parents during a typical week. Perceptions of siblings’ quantity of weekly alcohol use were significantly associated with participants’ quantity of alcohol use (r = .21, p = .006) and frequency of alcohol use (r = .23, p = .002). Perceptions of parental alcohol use were not related to the participants’ alcohol use patterns.  相似文献   

11.
Located in Qinghai Province of China, the Three Rivers Headwaters Region is the source region of the Yangtze, Yellow and Lantsang Rivers, and plays an important role in biodiversity conservation and regulating water supply. Despite many efforts on land use change in Qinghai, knowledge of the spatial variation of land use change is still lacking. This study examines the patterns of land use change across various watersheds, prefectures and the temple surroundings. Remote sensing images of 1987, 1997 and 2007 were analyzed to derive land use distributions; patterns and structures of the landscape were then quantified with landscape metrics. The results illustrated that the Yangtze River headwater region had more diverse and more evenly distributed landscape, while the Lantsang and the Yellow headwater regions showed a decline in landscape diversity. Comparison of the land use patterns of four prefectures revealed that Yushu Prefecture experienced an increase in landscape diversity from 1987 to 2007 while the land use patches in Guoluo Prefecture exhibited more aggregated patterns than other prefectures. Analysis of the spatial variations of land use change in the temple surroundings illustrated that 19.7% and 35.9% of the temples in Guoluo and Yushu Prefectures, respectively, encountered land use change for their immediate areas within 2 km. Comparison of the surroundings of temples and human settlements found that land use change was not evenly distributed, and that greater land use change had occurred for the surroundings of human settlements. Such findings provided insights into the spatial variation of land use change in the Three Rivers Headwaters Region.  相似文献   

12.
深圳市大鹏半岛土地利用变化对植被覆盖动态的影响   总被引:1,自引:0,他引:1  
城市化背景下的植被覆盖动态研究对于区域生态保护工作具有重要的指导意义.利用深圳市1995-2007年的遥感数据以及1996和2007年土地变更调查资料,基于归一化植被指数轨迹追踪分析和叠图代数计算方法,对大鹏半岛植被覆盖动态类型及其空间分异、土地利用变化结构和格局特征以及土地利用变化与植被覆盖动态之间的响应关系进行研究.结果表明:1995-2007年,研究区65%的地区植被覆盖发生显著改变,植被覆盖状况总体趋于好转;城市化和商品农业发展是该区土地利用动态变化的主要成因,研究时段内31%的地表发生了用地功能转变;土地利用变化是区内植被覆盖发生改变的重要成因之一,约35%的植被覆盖出现退降过程区域与土地功能转变有关;55%的用地功能转变区域因机械干扰导致植被覆盖退化,但至研究期末,大多数退化区域已经进入植被覆盖显著改善阶段.  相似文献   

13.
中国土地利用空间格局动态变化模拟——以规划情景为例   总被引:5,自引:0,他引:5  
孙晓芳  岳天祥  范泽孟 《生态学报》2012,32(20):6440-6451
土地利用变化研究在环境可持续发展研究领域中具有重要的地位,其空间分布格局的变化影响到生物地球化学循环、气候变化、生物多样性等。采用土地利用动态变化模型Dyna-CLUE模拟了在规划情景下中国土地利用变化未来空间分布格局。将土地利用类型分为六大类,即耕地、草地、林地、建设用地、水域和其它用地。驱动因子包括地形地貌、气候、社会交通等方面,对动态驱动因子如气温、降水、人口交通等,考虑了其在未来情景下的发展趋势。基于土地利用类型与驱动因子之间的定量关系和土地利用类型之间的转换规则等,模拟出至2020年中国土地利用分布格局。结果表明,至2020年,中国东南部、黄淮海平原、四川盆地等地区耕地面积将增加,东北、西北等农牧交错区、农林交错区和沙漠边缘耕地面积将会呈轻度减少趋势;林地面积将增加1417.91万hm2,主要发生在中国东北部以及西南部水热条件好的地区;中国草地在面积上保持稳定,空间上中东部、东南地区草地面积减少,内蒙古中部,青海东部,四川盆地北缘区和青藏高原等地面积增加;建设用地增加531.76万hm2,主要发生在中国的东部地区。  相似文献   

14.
目的 针对医疗机构的合理用药水平进行评价研究。方法 根据医疗机构合理用药的具体要求,构建医疗机构合理用药评价指标体系,采用基于模糊群决策的方法和多指标评价分析法构建医疗机构合理用药评价模型。结果 构建了基于模糊群决策的医疗机构合理用药评价模型,并通过实例分析证明了评价模型的可行性。结论 建立的基于模糊群决策的医疗机构合理用药评价模型能够对医疗机构的合理用药水平进行科学评价,为提高医疗机构合理用药水平奠定基础。  相似文献   

15.
Evolutionary rates in the adaptive radiation of beetles on plants   总被引:3,自引:0,他引:3  
Herbivorous insects and other small consumers are often specialized both in use of particular host taxa and in use of particular host tissues. Such consumers also often seem to show consistent differences in the rates of evolution of these two dimensions of host use, implying common processes, but this has been little studied. Here we quantify these rates of change in host use evolution in a major radiation of herbivorous insects, the Chrysomeloidea, whose diversity has been attributed to their use of flowering plants. We find a significant difference in the rates of evolutionary change in these two dimensions of host use, with host taxon associations most labile. There are apparently similar differences in rates of host use evolution in other parasite groups, suggesting the generality of this pattern. Divergences in parasite form associated with use of different host tissues may facilitate resource partitioning among successive adaptive radiations on particular host taxa.  相似文献   

16.
中国西南岩溶区水分利用效率变化及其对气象要素的响应   总被引:1,自引:0,他引:1  
水分利用效率(WUE,Water use efficiency)是衡量水资源利用率的重要指标,对气候变化有明显响应,中国西南岩溶区生态缺水严重,水资源利用问题亟需解决,但该区域水分利用效率对气象要素的响应仍不明晰。利用MODIS总初级生产力(Gross primary productivity,GPP)和蒸散发(Evapotranspiration,ET)数据集计算中国西南岩溶区的水分利用效率,结合气象数据和归一化植被指数(NDVI,Normalized difference vegetation index)数据,采用Theil-Sen Median趋势分析和Pearson相关分析,揭示了其水分利用效率的时空变化特征及对气象要素的响应。结果表明:2000-2014年中国西南岩溶区年水分利用效率与植被生长期水分利用效率(AGS-WUE)时间序列变化趋势相近,春、秋季水分利用效率呈上升趋势,夏季呈下降趋势;年水分利用效率呈上升趋势,与降水呈负相关,喀斯特地区与气温呈正相关,非喀斯特地区呈负相关,NDVI增长是主要驱动因素;年水分利用效率和AGS-WUE从东南到西北逐渐升高;非喀斯特地区水分利用效率高于大部分喀斯特地区;总体上高海拔地区水分利用效率高于低海拔地区。气温、海拔及喀斯特发育程度综合影响喀斯特地区水分利用效率。本研究结果能为提高喀斯特生态系统水分利用效率提供理论参考。  相似文献   

17.
This 1981 study is the 1st of its kind in Nepal. Analysis using a logit-linear model showed that contraceptive use in Nepal depends on many factors. Women aged 35-49 are 3 times more likely than women aged 15-24 to use contraceptives. Women with 4 or more children are 8 times more likely to use contraceptives than women with 1 or no children, and 2.5 times more likely than women with 2 or 3 children. The use of contraceptives is greatest among women whose offspring includes more sons than daughters, and least among women whose offspring are all daughters. Women who desire no more children are 5 to 6 times more likely to use contraceptives than women who desire more children. Women who have discussed desired family size with their husbands are more than 4 times more likely to use contraceptives than women lacking this type of communication. Women with some schooling are twice as likely to use contraceptives as women with no schooling. Contraceptive use is higher among women who do nonfarm work than farm work, and higher still among women who do not work. Urban women were almost twice as likely to use contraceptives as rural women. Women with less than 1 hour access to a family planning service outlet were 2 to 3 times more likely to use contraceptives than women whose access to these facilities was greater than 1 hour. The number of previous child losses per woman had no significant effect in contraceptive use. Conclusions are based on analysis of data from the Nepal Contraceptive Prevalence Survey, 1981.  相似文献   

18.
19.
Partial amputations of the hind legs were done in 44 rats. The femoral arteries and veins were repaired by microvascular techniques. The systemic use of heparin, the local use of magnesium sulfate, and the combined use of the two drugs, were evaluated as to their influence on preventing thrombosis in these microvascular anastomoses. No benefit could be demonstrated from the use of these drugs.  相似文献   

20.
Penicillin and streptomycin in experimental staphylococcal intoxication had different effects on the disease depending on the period of their use. Penicillin injections prior to administration of the toxin increased significantly the resistance of the animals to it, while with the use of streptomycin there was only a tendency to its increase. The use of both antibiotics against the background of the intoxication had a reverse effect: there was a tendency to a decreased animal resistance to a greater extent with the use of streptomycin. The use of tetracycline hydrochloride had no effect on the animal resistance to the staphylococcal toxin.  相似文献   

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