全文获取类型
收费全文 | 869篇 |
免费 | 24篇 |
国内免费 | 23篇 |
专业分类
安全科学 | 88篇 |
废物处理 | 16篇 |
环保管理 | 257篇 |
综合类 | 266篇 |
基础理论 | 131篇 |
环境理论 | 2篇 |
污染及防治 | 30篇 |
评价与监测 | 56篇 |
社会与环境 | 42篇 |
灾害及防治 | 28篇 |
出版年
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 27篇 |
2019年 | 17篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 46篇 |
2013年 | 53篇 |
2012年 | 37篇 |
2011年 | 66篇 |
2010年 | 38篇 |
2009年 | 46篇 |
2008年 | 45篇 |
2007年 | 50篇 |
2006年 | 48篇 |
2005年 | 41篇 |
2004年 | 32篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 25篇 |
2000年 | 24篇 |
1999年 | 15篇 |
1998年 | 17篇 |
1997年 | 20篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有916条查询结果,搜索用时 31 毫秒
881.
882.
基于2007年第一次全省农业种植业肥料流失普查数据及实测的32种种植模式的肥料流失系数,分析了不同种植作物结构、种植地块坡度、种植方向影响肥料流失的规律,提出云南省农业种植业肥料流失修正系数选取方法。 相似文献
883.
884.
石头口门水库藻类种群组成特征研究 总被引:2,自引:1,他引:1
2008年9月5日采集石头口门水库42份水样,制片,电子显微镜下观察,研究结果表明:藻类共有5门,7纲,15目,27科,47属。其中,绿藻门最多,2纲,4目,9科,20属;其次是硅藻门,2纲,5目。7科,11属;再次是蓝藻门,1纲,3目,8科,13属;黄藻门较少,1纲,2目,2科,2属;红藻门仅有1纲,1目,1科,1属。采用血球计数板计数法计算原始水样中的藻类的平均密度。得出石头口门水库藻类的平均密度为3.80×10^4个/L,变动范围在1.00×10^4~8.00×10^4个/L之间。绿藻门属的数量和密度分别占到了42,55%,88.39%,是石头口门水库的优势藻类种群。 相似文献
885.
甘肃省小柳沟铜钨矿区矿山环境遥感调查与监测 总被引:1,自引:0,他引:1
采用遥感和GIS技术,利用两个时相的QuickBird-2和SPOF-5影像对甘肃省小柳沟铜钨矿区2003—2008年矿产资源开发现状与矿山环境进行了遥感调查、监测研究与野外验证,结果表明:小柳沟矿区矿产资源开发总数量和总面积呈现大幅上升趋势,开采面积和矿产开发占地分别从21 587.91 m2、133 517.67 m2增加了151 535.82 m2和537 437.26 m2,其中矿石堆、工矿用地、尾矿库面积分别增加了8.3倍、7.5倍、6.2倍;矿区新构造运动和泥石流活动较强,矿业开发产生的大量废弃物对矿山环境构成了较大的威胁,在暴雨、构造活动等外界因素的诱发下,极易发生新的泥石流、滑坡等灾害。 相似文献
886.
2006年10月铁岭市按照辽宁省环境监测中心站土壤调查要求,依据《全国土壤调查总体实施方案》开始了典型区域样品采集工作,本文主要就利用GIS布置采样点和到达采样点如何导航做了技术上的经验分析。 相似文献
887.
人类抗灾体适能培养途径的研究 总被引:1,自引:1,他引:0
在<人类抗灾体适能的理论架构的研究>的基础上,通过问卷调查法、专家访谈法、数理统计法、查阅资料法、逻辑分析法等,进一步确认了人类抗灾体适能的概念、影响因素等;并分析了通过体育教育培养人类抗灾体适能的可行性,认为体育教育中人类抗灾体适能的培养途径有体育竞赛、长时间的球类活动、中长跑、长时间的健美操、游泳、定向越野与野外生存等. 相似文献
888.
Wei Wu Ji-long Chen Hong-bin Liu Axel Garcia y Garcia Gerrit Hoogenboom 《Agriculture, ecosystems & environment》2010,135(1-2):111-118
Soil and weather data are critical for the operation of crop simulation models. However, in many cases they are not readily available, especially applications at a regional or larger spatial scale. The Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) provides massive quantities of geo-referenced soil and weather data variables on a half-degree latitude–longitude grid covering the conterminous USA. The VEMAP data were derived from a range of products and analyses, including ground observations, cluster analyses, kriging interpolation, and data assimilation. The objective of this study was to convert the soil and daily weather data of VEMAP into a format that can be used in the popular modeling software Decision Support System for Agrotechnology Transfer (DSSAT). Users can select appropriate soil or daily weather information for the area of interest. The conversion of the VEMAP data resulted in 5927 unique soil profiles and 3261 unique weather station files that encompass daily data from 1895 to 1993. To demonstrate the utility of this database in DSSAT, one representative county of the state of Georgia, USA was selected and a soybean simulation model was employed to simulate final yield using the extracted soil and daily weather data for the normal year (1961–1990). Meanwhile, the extracted daily weather data were compared with ground station observations from the National Weather Service Cooperative Observer Program (COOP). The paired t-test showed that no significant differences were found between the daily weather data and between simulated yields based on VEMAP and COOP weather data for the selected location. The outcome of this research showed that the VEMAP data can be used for crop model applications. However, further research is needed to assess the accuracy of the datasets for a variety of crops at a regional or national scale. 相似文献
889.
Reducing fertiliser applications can reduce production costs for cotton (Gossypium hirsutum L.) growers, as well as nitrogen (N) leaching into the soil and contamination of surface and ground water. But altered N fertilisation may also affect pests and their natural enemies. In this study, plots with four different levels of fertiliser input (0, 45, 90 and 135 kg ha−1 N) were used to investigate the influence of N on cotton pest and beneficial arthropod populations, and on cotton yield in Tifton, GA, USA. We predicted that (1) N fertilisation will correlate positively with cotton plant growth; (2) increased N fertilisation will increase pest populations because plants with more N will be more nutritious for and attractive to herbivores; (3) populations of beneficial arthropods and predation of pests will decline with increased N fertilisation because of reduced plant signaling; (4) increased N fertilisation will increase pest mortality due to parasitoids because of increased host quality. Cotton plant growth was enhanced by N fertilisation but yield was unaffected. N fertilisation significantly affected some pest arthropods but inconsistently. Mirids were most abundant in the high N treatment in 1 year of the study and cotton aphids were most abundant in the highest N treatment in the other year of the study. Arthropod predators were generally more abundant in the high N treatment but only spiders and Geocoris spp. were significantly affected by N treatment, with highest numbers present in the highest N treatment but the significant differences were each only in a single year. The greatest mortality of sentinel pest eggs (Spodoptera exigua) due to predation occurred under low N conditions. N fertilisation had no significant effects on parasitism of feral or sentinel caterpillars. 相似文献
890.
对静态GPS在管线控制测量中的应用做了阐述,包括选点、数据采集和数据处理,结合GPS自带的后处理软件,以实例介绍了在数据处理中遇到的问题和解决方法. 相似文献