全文获取类型
收费全文 | 1291篇 |
免费 | 232篇 |
国内免费 | 29篇 |
专业分类
安全科学 | 358篇 |
废物处理 | 39篇 |
环保管理 | 308篇 |
综合类 | 519篇 |
基础理论 | 132篇 |
污染及防治 | 47篇 |
评价与监测 | 67篇 |
社会与环境 | 58篇 |
灾害及防治 | 24篇 |
出版年
2025年 | 20篇 |
2024年 | 27篇 |
2023年 | 57篇 |
2022年 | 61篇 |
2021年 | 54篇 |
2020年 | 44篇 |
2019年 | 57篇 |
2018年 | 52篇 |
2017年 | 69篇 |
2016年 | 50篇 |
2015年 | 59篇 |
2014年 | 56篇 |
2013年 | 74篇 |
2012年 | 66篇 |
2011年 | 91篇 |
2010年 | 58篇 |
2009年 | 66篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 75篇 |
2005年 | 54篇 |
2004年 | 37篇 |
2003年 | 40篇 |
2002年 | 44篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 25篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1987年 | 5篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1971年 | 4篇 |
排序方式: 共有1552条查询结果,搜索用时 0 毫秒
91.
东湖、汤逊湖和梁子湖沉积物磷形态及pH对磷释放的影响 总被引:4,自引:0,他引:4
文章采用淡水沉积物中磷形态标准测试程序(SMT)研究了东湖、汤逊湖和梁子湖沉积物中磷的形态分布,并比较了不同pH条件下沉积物磷释放特征的差异性。结果表明:东湖沉积物总磷质量分数最高,平均值1.232 mg.g-1,其次为汤逊湖(0.762mg.g-1),梁子湖沉积物总磷质量分数最低(0.572 mg.g-1);3个湖泊上覆水总磷质量浓度也表现出类似的变化规律,线性相关性分析显示上覆水中总磷质量浓度与沉积物总磷质量分数显著正相关。东湖和梁子湖沉积物总磷中无机磷和有机磷所占比例较接近,汤逊湖无机磷所占比例远低于有机磷。不同湖泊之间磷形态的分布并没有一定的规律性,湖泊的地理分布以及人为因素可能是造成磷形态差异的主要因素。当pH为2.0~7.0时,3个湖泊沉积物中溶解性活性磷(SRP)释放量均呈先增加后减小的趋势;当pH为7.0~12.0时,SRP释放量呈增加趋势。相关分析结果表明,SRP的释放与有机质的质量分数无显著相关性。方差分析结果显示3个湖泊沉积物在黏粒和粉粒组成上均没有显著差异(P>0.1),表明实验样品的粒径组成不是造成各个湖泊间磷释放差异的原因。不同pH条件下,SRP释放量与沉积物总磷质量分数显著正相关;酸性环境下,SRP释放量与酸式磷(HCl-P)的相关性优于碱式磷(NaOH-P),碱性环境下则刚好相反。 相似文献
92.
Heikens A Widianarko B Dewi IC De Boer JL Seinen W van Leeuwen K 《Environmental geochemistry and health》2005,27(5-6):409-418
In Asembagus (East Java, Indonesia) irrigation water is contaminated with effluent from the hyperacid Ijen Crater Lake resulting
in a low pH and high levels of various elements. As a first step towards a risk assessment, locally produced food items (rice,
maize, cassava leaf, cassava root, peanuts) were collected and concentrations of As, B, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni,
Pb, V, Zn were compared to samples from a reference area and with literature values. Further, concentrations in rice were
compared to total soil concentrations in paddy fields. Compared to the reference area, food items produced in the contaminated
area had increased levels of Cd, Co, Ni and Mn in particular, while levels of Mo were lower. In contrast, total soil concentrations
of Cd and Mn in particular have decreased whereas especially Mo was increased. In combination with the observed soil acidification,
it is likely that the bioavailable concentration of most elements in the contaminated soil is higher (except for Mo) due to
an increased weathering rate and/or input via the contaminated irrigation water. In terms of human health, concentrations in foods were generally within normal literature
values. However, it was observed that essential elements (in particular Fe) known for their inhibitory effects on e.g. Cd
and Mn toxicity did not accumulate in crops whereas Cd and Mn did. 相似文献
93.
以江苏省里下河腹部地区38个典型湖泊湖荡为研究对象,分析了春季浮游植物群落结构特征及其与环境因子的关系,运用了基于理化指标的综合营养状态指数(TLI)评价方法和基于浮游植物群落结构分析的生物指标(Shannon-Wiener多样性指数H′和Pielou均匀度指数J)评价方法,评价了湖泊湖荡营养状态.结果显示共采集到里下河腹部地区湖泊湖荡浮游植物7门50属89种,主要隶属于绿藻门(Chlorophyta)和硅藻门(Bacillariophyta);浮游植物细胞丰度介于2.3×10~5~3.7×10~7 cells·L~(-1),生物量介于0.05~15.02 mg·L~(-1),绿藻门与隐藻门(Cryptophyta)在细胞丰度上占优势,隐藻门在生物量上占优势;梅尼小环藻(Cyclotella meneghiniana)、啮蚀隐藻(Cryptomonas erosa)、尖尾蓝隐藻(Chroomonas acuta)、四尾栅藻(Scenedesmus guadricauda)为主要优势种;生物指标评价方法的结果显示湖泊湖荡总体为轻度富营养,与TLI评价方法的结果有较好一致性,表明两类评价方法在里下河腹部地区具有较强内在关联性. 相似文献
94.
采煤塌陷地积水对土壤氮素矿化过程的影响 总被引:1,自引:0,他引:1
煤炭开采导致大面积的土地塌陷,使大量耕地出现常年积水或季节性积水,对塌陷地土壤氮素矿化过程产生一定影响。采集了某矿采煤塌陷地土壤样品,进行好气和淹水培养条件下间歇淋洗培养实验,研究了塌陷地积水对土壤氮素矿化过程的影响。经过62d的培养,40d左右氮素的矿化过程趋于稳定,淹水培养条件下土壤氮素最终累积矿化量为68.99mg/kg,约为好气培养条件的10倍,且淹水培养条件下土壤氮素矿化势可达69.472mg/kg,均矿化速率为5.210mg/(kg·d),说明淹水对土壤氮素矿化过程有显著的促进作用。将实验所得累积矿化量分别代入简单指数模型及双因子指数模型进行拟合,发现简单指数模型能有效模拟好气和淹水培养条件下土壤氮素矿化过程,并获得了2种培养条件下土壤氮素矿化过程的模型参数。 相似文献
95.
96.
从煤炭主体专业教育具有的公益性属性分析入手,指出煤炭主体专业的办学经费日紧和煤炭主体专业边缘化与去煤化,公益性日渐式微.建议从国家、高校、企业、个人家庭等各个层次全方位重构煤炭主体专业教育的公益性,加强国家利益至上,强化政府主渠道作用,在政策与教育投入要向其倾斜,优先发展与保障煤炭主体专业的教育,制定相关法规确保煤炭专业生源与人才培养质量,并在该领域就业.国家、企业、高校与个人家庭利益相关者都应在制度上强化各自应有的责任,从而形成一个多层次全方位良性互动发展的培养与吸纳人才的机制,确保煤炭主体专业教育的公益性,促进煤炭主体专业健康发展,满足安全生产的人才需求的供给,从而为煤炭安全生产提供重要保障. 相似文献
97.
Water Resource Management in Botswana: Balancing Sustainability and Economic Development* 总被引:1,自引:0,他引:1
Dianne Rahm Larry Swatuk Erica Matheny 《Environment, Development and Sustainability》2006,8(1):157-183
Botswana is a rapidly developing country in southern Africa. Over the last three decades, diamond mining and tourism have
provided double-digit rates of economic growth. Yet most of Botswana’s land is in the Kalahari desert where the climate is
subject to sustained periods of severe drought. In this environment, water resources are the most crucial of all environmental
resources. Water use directly affects economic development because water utilization impacts all the major national economic
sectors. A sustainable water use resource management plan must stretch several decades into the future to assure the availability
of adequate supplies of water to future generations while not compromising the ability of the current generation to reasonable
rates of economic development. Yet thinking about sustainability is present in Botswana water policy mostly only in rhetoric.
A series of cultural traditions and political constraints, coupled with bureaucratic managerial weaknesses, serve to maintain
a system of water allocation that is unsustainable in the long run and inefficient in the short-term. Unless sustainable water
use patterns are adopted, the results for the short-term, as well as the long-term, will be devastating. Drawing on data obtained
through a series of interviews with government officials, leaders of non-governmental organizations (NGOs), and water resource
researchers, this paper explores water policy in Botswana within the larger context of sustainable natural resource management
practice and the pressures of economic development.
This research was partially funded under U.S. Department of State, College and University Affiliations Grant # ASCS-1095. 相似文献
98.
复垦对恢复矿区土壤生态功能极为重要,但不同复垦措施下土壤生态功能重建的微生物学机制尚不清晰.厘清不同复垦措施下土壤细菌、真菌群落特征、组装过程及其与理化性质的关系,对重塑矿区土壤生态稳定性至关重要.采用宏基因组测序技术并结合零模型,分析复垦自然恢复区(LH)和复垦农田区(MM)土壤微生物多样性、群落组成、网络结构及群落组装过程的差异.结果表明:①与LH处理相比,MM处理显著提高了土壤养分含量,全氮(TN)、全磷(TP)、有效磷(AP)和速效钾(AK)含量分别提高了34.70%、72.72%、468.98%和45.74%(P<0.05).②LH处理和MM处理下细菌和真菌的优势菌群均未发生变化,但细菌优势菌群落丰度发生显著变化.与LH处理相比,MM处理酸杆菌门(Acidobacteria)相对丰度显著增加5.4%,念珠菌门(Candidatus Rokubacteria)相对丰度显著降低235.72%,不同复垦措施下细菌与真菌群落指示微生物发生改变(P<0.05).③与LH处理相比,MM处理细菌网络复杂性增强,真菌网络复杂性降低,MM处理土壤细菌节点数、连接数均增加.LH处理的关键类群为念珠菌门和浮霉菌门(Planctomycetes),MM处理的关键类群为变形菌门(Proteobacteria).真菌的关键类群均为子囊菌门(Ascomycota).④确定性过程主导了细菌和真菌群落的组装,LH处理细菌群落组装以同质性选择贡献最大,MM处理以异质性选择贡献最大;真菌群落均以异质性选择为主.这些结果为采煤沉陷复垦区土壤微生物群落结构及生态功能恢复提供了新见解. 相似文献
99.
Surface water was taken from river mouth to the central area of Meiliang Bay, Taihu Lake, a large shallow eutrophic lake in China. Suspended solids were condensed by centrifugation 25L surface water samples from each selected site. Suspended solids and surface sediments were further freeze-dried and microwave digested before determining the metals by ICP-AES. Among the metals analyzed in suspended solids and sediments, contents of Cr, Cu, Mn, Ni, and Zn in suspended solids were significantly higher than those in sediments while contents of AI, Ba, Be, Ca, Co, Fe, K, Mg, Pb, and V in suspended solids were 10%-30% higher than those in sediments. Sr and Ti contents in suspended solids and sediments were very similar. Na content in suspended solids was lower than that in sediments. Heavy metals were significantly accumulated in suspended solids. From the river mouth to the center of Meiliang Bay, contents of Cr, Cu, Pb, and Zn in suspended solids showed a gradual decreasing trend indicating the river(Zhihugang River) still discharged large quantity of heavy metals to Meiliang Bay. The study suggests that the geochemical behaviors and ecological effects of heavy metals in suspended solids may serve as a good indicator for the pollution of lake. 相似文献
100.
生态脆弱性评价在矿区规划环评中的应用研究——以阜新矿区为例 总被引:1,自引:0,他引:1
以辽宁阜新矿区总体规划环评为例,基于生态环境指数,生态敏感性和景观空间结构等指标构建矿区开发生态脆弱性评价指标体系,运用层次分析和综合指数法评价和划分区域生态脆弱性等级,利用GIS技术并结合法规要求将规划矿区划分为适宜、优化、适度、限制和禁止开采等5类地区.评价结果表明,阜新矿区生态脆弱性整体较高,脆弱度属于4级和5级的区块分别约占规划总面积的51.38%和39.36%,且已建和规划新建煤矿全部处在脆弱性较高的区域范围内,矿区开发与生态保护之间的矛盾突出. 相似文献