全文获取类型
收费全文 | 22922篇 |
免费 | 1639篇 |
国内免费 | 4922篇 |
专业分类
安全科学 | 3386篇 |
废物处理 | 340篇 |
环保管理 | 3025篇 |
综合类 | 13076篇 |
基础理论 | 3107篇 |
环境理论 | 12篇 |
污染及防治 | 2113篇 |
评价与监测 | 1409篇 |
社会与环境 | 1803篇 |
灾害及防治 | 1212篇 |
出版年
2024年 | 106篇 |
2023年 | 432篇 |
2022年 | 668篇 |
2021年 | 814篇 |
2020年 | 784篇 |
2019年 | 699篇 |
2018年 | 666篇 |
2017年 | 908篇 |
2016年 | 1070篇 |
2015年 | 1124篇 |
2014年 | 1152篇 |
2013年 | 1571篇 |
2012年 | 1725篇 |
2011年 | 1841篇 |
2010年 | 1395篇 |
2009年 | 1338篇 |
2008年 | 1119篇 |
2007年 | 1572篇 |
2006年 | 1587篇 |
2005年 | 1214篇 |
2004年 | 1022篇 |
2003年 | 1071篇 |
2002年 | 840篇 |
2001年 | 723篇 |
2000年 | 632篇 |
1999年 | 610篇 |
1998年 | 485篇 |
1997年 | 374篇 |
1996年 | 341篇 |
1995年 | 295篇 |
1994年 | 269篇 |
1993年 | 232篇 |
1992年 | 194篇 |
1991年 | 142篇 |
1990年 | 91篇 |
1989年 | 56篇 |
1988年 | 52篇 |
1987年 | 33篇 |
1986年 | 24篇 |
1985年 | 36篇 |
1984年 | 18篇 |
1983年 | 22篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1977年 | 16篇 |
1974年 | 8篇 |
1973年 | 15篇 |
1972年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
371.
Cu, Cr, Mn, Ni and Zn contents were quantified for three wild-growing edible species of macrofungi (Boletus edulis, Macrolepiota procera and Cantharellus cibarius) and underlying soil samples collected at forest sites in Lubuskie voivodeship, Poland. The total concentration of the analysed elements was determined using an ASA iCE 3000 series atomic absorption spectrometer. The analysis found significant differences in bioaccumulation between species and differing distributions of trace elements in the caps and stalks of fruiting bodies. Bioaccumulation factors revealed that Zn and Cu are the most bioaccumulated elements, whereas Cr and Mn are excluded from bioaccumulation. Macrolepiota procera showed the highest bioaccumulation of Cu, and Zn is accumulated to the greatest extent by Boletus edulis. A few significant differences (p≤0.05) between the examined species were observed. 相似文献
372.
Theoretical arguments for using a term structure of social discount rates (SDR) that declines with the time horizon have influenced government guidelines in the US and Europe. The certainty equivalent discount rate that often underpins this guidance embodies uncertainty in the primitives of the SDR, such as growth. For distant time horizons the probability distributions of these primitives are ambiguous and the certainty equivalent itself is uncertain. Yet, if a limited set of characteristics of the unknown probability distributions can be agreed upon, ‘sharp’ upper and lower bounds can be defined for the certainty-equivalent SDR. Unfortunately, even with considerable agreement on these features, these bounds are widely spread for horizons beyond 75 years. So while estimates of the present value of intergenerational impacts, including the social cost of carbon, can be bounded in the presence of this ambiguity, they typically remain so imprecise as to provide little practical guidance. 相似文献
373.
Plant conservation initiatives lag behind and receive considerably less funding than animal conservation projects. We explored a potential reason for this bias: a tendency among humans to neither notice nor value plants in the environment. Experimental research and surveys have demonstrated higher preference for, superior recall of, and better visual detection of animals compared with plants. This bias has been attributed to perceptual factors such as lack of motion by plants and the tendency of plants to visually blend together but also to cultural factors such as a greater focus on animals in formal biological education. In contrast, ethnographic research reveals that many social groups have strong bonds with plants, including nonhierarchical kinship relationships. We argue that plant blindness is common, but not inevitable. If immersed in a plant‐affiliated culture, the individual will experience language and practices that enhance capacity to detect, recall, and value plants, something less likely to occur in zoocentric societies. Therefore, conservation programs can contribute to reducing this bias. We considered strategies that might reduce this bias and encourage plant conservation behavior. Psychological research demonstrates that people are more likely to support conservation of species that have human‐like characteristics and that support for conservation can be increased by encouraging people to practice empathy and anthropomorphism of nonhuman species. We argue that support for plant conservation may be garnered through strategies that promote identification and empathy with plants. 相似文献
374.
K.R. Renjith V. Sudheesh Anu Shaji Ejin George Manju Mary Joseph C.S. Ratheesh Kumar 《毒物与环境化学》2016,98(1):36-52
The spatial and temporal variations of some trace metals in the surface sediments of Cochin Estuary were analyzed along with their geochemical associations to identify the possible sources, bioavailability and the health risks posed by them. The dominance of kaolinite and suggested that clay minerals distribution is influenced by sediment sorting. Total metal analysis revealed enrichment for Cd, Pb and Zn due to anthropogenic activities. The speciation analysis established that notwithstanding the large availability, carbonate as well as organic and sulfides bound fractions showed negligible associations with most of the metals. Hydrous Fe–Mn oxides appeared to play a major role in controlling the fate and transport of these metals in the sediments of Cochin Estuary. Lower contribution of the residual fractions for Cd (21%–26%), Pb (<60%) and Zn (24%–42%) indicated an obvious increase of other geochemical fractions. Risk assessment analysis revealed that regardless of total concentration, none of the analyzed metals were at safe levels in the estuary as appreciable percentages were found to be associated with mobile geochemical forms. The speciation study conspicuously established that the metals originating from non-geogenic sources are largely associated with the labile fractions and hence are more detrimental to the aquatic biota. 相似文献
375.
2019年新冠疫情席卷全球,在疫情环境下,医疗废物大幅增多,全国各大城市纷纷出现医疗废物处置不当的现象。本文对国内外现状分析,在认知、设施、管理和监督四个方面发现存在一定的问题,通过加强教育、加大储备、完善机制和改善监管的建议,为提升医疗废物应急处置能力提供参考。 相似文献
376.
对宜昌市沮漳河流域当阳段的水环境进行了调查和评价。通过区域自然环境、社会经济发展、水体功能区、水环境容量等分析以及多个断面数据的监测,表明沮漳河流域当阳段水环境质量不能满足Ⅲ类水体功能区要求,主要超标因子为高锰酸盐指数、NHrN、BOD5、TP、石油类,主要受沿岸工业废水、生活污水及农业面源污染所致。 相似文献
377.
参照《纳氏试剂分光光度法》的方法原理,用分光光度计对3种光程长度比色皿分别进行比色,探讨不同光程长度比色皿间关系。 相似文献
378.
康乐 《辽宁城乡环境科技》2013,(5):33-35
评述了近年来城市污水生物脱氮除磷理论和功能微生物的研究进展,重点介绍了生物处理的新方法:短程硝化反硝化处理法、厌氧氨氧化处理法、同步硝化反硝化处理法、同步反硝化除磷脱氮法,并总结了各处理工艺的应用状况。对生物脱氮除磷微生物学和新的理论技术发展趋势做出了展望。 相似文献
379.
系统分析了辽河流域近十年社会经济和水污染物排放之间的关系,基于污染物排放强度和人均GDP指标,建立辽河流域COD和氨氮环境学习曲线;结合情景分析法预测在现有治污水平下,辽河流域未来水污染物排放趋势及水环境压力。结果表明,辽河流域水环境压力巨大。根据辽河流域污染治理中存在的实际问题,提出新时期的污染治理模式。 相似文献
380.
通过对克山县2003—2012年的空气监测数据分析,二氧化硫和总悬浮物颗粒物呈下降趋势,氮氧化物和降尘浓度变化不大;尘类是影响环境质量的主要污染物,县区环境空气质量呈轻度污染,根据各年度的监测数据来看,环境空气质量逐年得到改善。 相似文献