首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   81篇
  免费   6篇
  国内免费   18篇
安全科学   2篇
环保管理   9篇
综合类   60篇
基础理论   20篇
评价与监测   3篇
社会与环境   8篇
灾害及防治   3篇
  2023年   5篇
  2022年   5篇
  2021年   5篇
  2019年   1篇
  2018年   1篇
  2016年   3篇
  2015年   7篇
  2014年   2篇
  2013年   5篇
  2012年   10篇
  2011年   5篇
  2010年   2篇
  2009年   3篇
  2008年   4篇
  2007年   9篇
  2006年   3篇
  2005年   1篇
  2004年   2篇
  2003年   5篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   6篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
排序方式: 共有105条查询结果,搜索用时 265 毫秒
1.
海南省旅游地评价及其开发研究   总被引:9,自引:2,他引:9  
旅游地资源评价和开发研究,是进行旅游开发宏观决策,确定对应的旅游活动类型和接待规模,指导旅游市场开发与景区、景点设计时一项重要的基础研究工作。本文以海南省为例,对旅游地资源的评价制图和旅游开发用地预测方法,进行了有益的探讨。  相似文献   
2.
海南岛水稻气候生产潜力和人口承载量的估算   总被引:2,自引:0,他引:2  
本文从海南岛自然优势出发,采用联合国粮农组织《产量与水的关系》中介绍的气候生产潜力的农业生态方法: 计算了海南水稻的气候生产潜力,从海南岛水稻生产和人口的现状出发,采用灰色系统中的GM(1,1)预测模型:计算和探讨了当前和未来水稻生产的人口承载量问题。试图揭示水稻生产的现状、问题和发展前景,为全岛水稻的产、销、购提供科学依据。  相似文献   
3.
<正> According to the leading national classification of the climate of China, given by B. Huang (revised version 1986), Hainan falls into the tropical climatic realm, subdivided into a "peripheral tropical" type for the northern part and a "middle tropical" type for the southern part of the island. While all-year-round frost-free conditions define the tropics in general, the 20t-isotherm for the coldest month represents the boundary between the peripheral tropical and middle tropical types. Compared to the tropical climate in general, Hainan experiences distinctly lower winter temperatures which thus result in a larger annual temperature variation. In terms of precipitation, Hainan records a long rainy season through the southwest monsoon and typhoon seasons from May until October while winter precipitation is comparably lower. Representing two agroclimatic hazards, strong typhoon winds and cold waves seriously affect Hainan. Although to be defined as "marginal tropica-1", the climatic conditions on Hainan  相似文献   
4.
海南特区农村剩余劳动力资源的开发与利用   总被引:1,自引:0,他引:1  
本文论述了海南特区农村剩余劳动力资源的现状及其影响劳动力资源开发利用的主要因素,提出了海南特区农村剩余劳动力资源开发与利用的途径。  相似文献   
5.
本文对海南东环铁路海口城区的南海大道附近的敏感点列车开通的近期(2020年)和远期(2030年)的噪声进行预测:根据噪声暴露声级与等效声级的关系公式,对列车加密后南海大道距离轨道30m处的噪声进行预测,发现当小时列车数达到14车次时,其昼问等效声级将超过70dBA的标准,为城区段控制小时列车次数提供参考。  相似文献   
6.
The development of rubber industry depends on the sustainable management of rubber plantation. To evaluate the environmental effects of planting Hevea brasiliensis on a subsystem of tropical forest ecosystem, the variation of soil fertility and carbon sequestration under rubber plantation within 30-year life period were investigated in Hainan Island. Results showed that (1) with the increase of stand age of rubber plantation, soil fertility decreased all along. From 1954 to 1995, soil organic matter, total N, available K and available P decreased by 48.2%, 54.1%, 56.7% and 64.1%, respectively. (2) If the complete return of litters was considered without additional fertilizer application to the soil of the rubber plantations, the consumption periods for P, N, K, Mg were only 825 years, 329 years, 94 years and 65 years, respectively~ To improve soil fertility is essential for rubber plantation development. (3) The C sequestration of rubber trees per hectare accounts for 272.08 t within 30-year life period and 57.91% of them was fixed in litters. In comparison with C sequestration by rain forest (234.305 t/hm^2) and by secondary rain forest (150.203 t/hm^2), rubber forest has more potentials for C fixation. On the base of above results, the following measures would benefit the maintenance of soil fertility and the development of rubber industry, including applying fertilizer to maintain the balance of soil nutrients, intercropping leguminous plant to improve soil fertility, reducing the collection of litters, optimizing soil properties to improve element P availability such as applying CaCO3. The information gathered from the study can be used as baseline data for the sustainable management of rubber plantation elsewhere.  相似文献   
7.
海南省位于我国热带地区,草本植物微量元素组成可反映热带区域生物地球化学特点。海南植物微量元素含量属正常范围值,仅个别植物Cd、Hg含量偏高。植物Zn、Cu、Mo含量大多在5mg/kg以上,Pb、Cu、Cd含量一般低于2mg/kg,Hg、As、Ni通常不足1mg/kg。雀稗(Paspalumcommersoni)、地胆草(Elephantopusscaber)等微量元素含量普遍较高。红裂稃草(Schizachyriumsanguineum)、白茅(Imperatacylindrica)等微量元素含量一般较低。植物微量元素组成与植物种类及其生境条件有关。生物吸收系数反映植物摄取元素的强度,Mo、Cd、Hg、Zn、Cu的生物吸收系数通常大于1.0,属强积聚元素,Pb、Cr、Ni、As的生物吸收系数大多低于0.3,是弱摄取元素。  相似文献   
8.
利用海南省18个气象台站的雷暴人工观测资料和海南闪电定位网的观测资料,分析了海南文昌火箭发射场的雷暴特征和雷电环境,结果表明:海南岛的中部和北部雷暴活动较强,西部、东部和南部近海地区的雷暴活动较弱,文昌发射场处在北部较强的雷暴区;采用Krigine(克里格)方法拟合的结果为文昌火箭发射场雷暴日数的年变化从1982年以后逐渐减少,发射场一年中各月都有雷暴发生,4-10月为雷暴高发期;发射场西部、西北部和北部区域雷暴活动较其它区域要强,79%的雷电流强度小于40 kA,而只有5.9%的雷电流强度大于60 kA,一天中闪电的发生有两个高峰时段,一个出现在凌晨5时到6时,另一个时段出现在14时到18时,午后15时左右是闪电活动最频繁的时段。  相似文献   
9.
The establishment of the forest eco-compensation mechanism could realize the value of the forest ecosystem services partly or thoroughly, stress the equality of the stakeholders, encourage public participation in forest ecosystem tendering, and strengthen the capacity of sustainable management. Taking the Hainan province as an example, this study focuses on the analysis of major socioeconomic and ecological impacts of forest eco-compensation in the Qiongzhong County and Lingshui County, and recommends approaches and practices for the establishment of the eco-compensation mechanism in the Hainan Province. Data were collected from a household questionnaire survey. Altogether 120 households have been interviewed, and Statistical Product and Service Solutions (SPSS) was applied for data analysis. Most of the respondents held a positive attitude toward the forest eco-compensation policy which has contributed to the improvement of environmental quality. However, forest protection has limited the opportunities for the income growth of local communities, who have never got sufficient compensation from either the central or local governments. Insufficient financial support to forest institutions and local communities involved in forest management has led to major conflicts in forest management, such as, the conflict between forest protection and local economic development, and decrease in arable land area and increase in surplus labor force. On the basis of case study results, the core issues of forest eco-compensation mechanism in Hainan province are discussed. Finally, suggestions and recommendations that cover forest eco-compensation standards, management institutions, and community capacity building and diversification of financing channels, have been made for the establishment of forest eco-compensation mechanism in Hainan.  相似文献   
10.
雷州半岛与海南岛砖红壤养分比较研究罗凯(广东省徐闻县农村工作委员会,徐闻524100)ComparisonofNutrientsContentofLatosolsinLeizhouPeninsulaandHainanIsland¥LuoKai(Rur...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号