全文获取类型
收费全文 | 1785篇 |
免费 | 566篇 |
国内免费 | 108篇 |
专业分类
安全科学 | 27篇 |
废物处理 | 11篇 |
环保管理 | 240篇 |
综合类 | 745篇 |
基础理论 | 1109篇 |
污染及防治 | 149篇 |
评价与监测 | 66篇 |
社会与环境 | 110篇 |
灾害及防治 | 2篇 |
出版年
2025年 | 9篇 |
2024年 | 55篇 |
2023年 | 76篇 |
2022年 | 87篇 |
2021年 | 95篇 |
2020年 | 105篇 |
2019年 | 84篇 |
2018年 | 63篇 |
2017年 | 92篇 |
2016年 | 85篇 |
2015年 | 102篇 |
2014年 | 90篇 |
2013年 | 132篇 |
2012年 | 114篇 |
2011年 | 154篇 |
2010年 | 108篇 |
2009年 | 116篇 |
2008年 | 124篇 |
2007年 | 142篇 |
2006年 | 93篇 |
2005年 | 104篇 |
2004年 | 73篇 |
2003年 | 61篇 |
2002年 | 41篇 |
2001年 | 29篇 |
2000年 | 39篇 |
1999年 | 27篇 |
1998年 | 23篇 |
1997年 | 19篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2459条查询结果,搜索用时 15 毫秒
391.
Decabromodiphenyl ether (BDE-209) is a prevalent polybrominated diphenyl ether (PBDE) congener known to have neurotoxicity. Effects of BDE-209 on Neuro-2a cells were performed in the present study and the possible apoptotic pathway was discussed. Results indicated that BDE-209 induced Neuro-2a cell apoptosis, increased the protein expression of Fas and Fas-associated death domain-containing protein (FADD) and activated the caspase-8 and -3 activities in a concentration-dependent manner, inferring the death-receptor pathway was involved in the apoptotic process. Meanwhile, BDE-209 exposure increased the Bax/Bcl-2 ratio and decreased the cellular mitochondrial membrane potential (MMP) which led to cytochrome C released to the cytoplasm. The intracellular caspase-9 was elevated simultaneously, which caused downstream caspase cascade and triggered cell apoptosis. Moreover, BDE-209 exposure increased cellular reactive oxygen species (ROS) level in a concentration-dependent manner and the addition of N-acetyl-l-cysteine (NAC), known as ROS scavengers, obviously reduced the apoptotic rate and a positive relationship was observed between the degree of apoptosis blocking and the loss of MMP and ROS production. We thus concluded that BDE-209 induced Neuro-2a cell apoptosis via the combination of the death-receptor signaling pathway and the mitochondrial signaling pathway. The elevated ROS production was considered to magnify the intracellular apoptosis signal and played a crucial role in apoptosis of Neuro-2a cells induced by BDE-209. 相似文献
392.
393.
Kerry A. Brown J. Carter Ingram Dan F. B. Flynn Rova Razafindrazaka Vololoniaina Jeannoda 《Environmental management》2009,44(1):136-148
Despite their prevalence in both developed and developing countries, there have been surprisingly few field assessments of
the ecological effectiveness of protected areas. This study aimed to assess the effectiveness of a key protected area in eastern
Madagascar, Ranomafana National Park (RNP). We established paired 100 × 4-m vegetation transects (400 m2) within RNP and in remnant forests in the park’s peripheral zone. In each 400-m2 plot, all woody stems >1.5 cm in diameter at breast height were measured and identified to species. All species were also
identified as native or non-native. We identified utilitarian species within all transects and they were sorted into use category.
We calculated plot-level taxonomic biodiversity and functional diversity of utilitarian species; the latter was calculated
by clustering the multivariate distances between species based on their utilitarian traits, and all metrics were tested using
paired t-tests. Our results showed that there was significantly higher biodiversity inside RNP than in remnant forests and this pattern
was consistent across all diversity metrics examined. Forests not located within the park’s boundary had significantly higher
non-native species than within RNP. There was no statistically significant difference in functional diversity of utilitarian
species inside RNP vs. remnant forests; however, the overall trend was toward higher diversity inside park boundaries. These
findings suggested that RNP has been effective at maintaining taxonomic diversity relative to surrounding unprotected areas
and restricting the spread of non-native plants. The results also suggested that low functional redundancy of forests outside
of RNP might be of concern, because residents in surrounding villages may have few other substitutes for the services provided
by species that are of critical importance to their livelihoods. This study highlights the challenges of trying to reconcile
biodiversity conservation with human use of natural resources in economically poor, remote areas. 相似文献
394.
Diane L. Larson Laura Phillips-Mao Gina Quiram Leah Sharpe Rebecca Stark Shinya Sugita Annie Weiler 《Journal of environmental management》2011
Applying the concept of sustainability to invasive species management (ISM) is challenging but necessary, given the increasing rates of invasion and the high costs of invasion impacts and control. To be sustainable, ISM must address environmental, social, and economic factors (or “pillars”) that influence the causes, impacts, and control of invasive species across multiple spatial and temporal scales. Although these pillars are generally acknowledged, their implementation is often limited by insufficient control options and significant economic and political constraints. In this paper, we outline specific objectives in each of these three “pillars” that, if incorporated into a management plan, will improve the plan’s likelihood of sustainability. We then examine three case studies that illustrate how these objectives can be effectively implemented. Each pillar reinforces the others, such that the inclusion of even a few of the outlined objectives will lead to more effective management that achieves ecological goals, while generating social support and long-term funding to maintain projects to completion. We encourage agency directors and policy-makers to consider sustainability principles when developing funding schemes, management agendas, and policy. 相似文献
395.
以江苏省盐城市大丰区沿海地区为研究区域,选择中山杉(
396.
397.
在三江源地区冬虫夏草3个产区——青海省黄南藏族自治州泽库县、果洛藏族自治州玛沁县和玉树藏族自治州杂多县设置虫草采挖样地和对照样地,通过样方调查和统计分析,评价冬虫夏草采挖活动对草地植被的影响. 结果表明:冬虫夏草采挖使草地物种多样性、盖度和地上生物量降低,群落优势度升高.由于采挖活动,Shannon-Wiener多样性指数减少了10.3%~12.5%,群落盖度降低了10.6%~19.1%,地上生物量降低了20.7%~46.1%,Berger-Parker优势度指数增加了16.7%~31.8%. 采挖活动未使地下生物量产生显著变化. 植被状况的恶化将影响冬虫夏草的形成过程,因此,应加强冬虫夏草产区的植被保护,以实现资源的可持续利用. 地上生物量对冬虫夏草采挖活动最为敏感,可作为冬虫夏草产区植被保护过程中的首选评价指标. 采挖活动对地上生物量的影响程度与地理位置有关,表明采挖活动的效应具有区域分异特征,冬虫夏草资源保护策略应根据区域特点制订. 相似文献
398.
399.
我国水生生物水质基准推导的物种选择 总被引:1,自引:2,他引:1
水生生物水质基准旨在保护水生生物不受水体中化学物质的有害影响,是水质基准体系的重要组成部分.不同区域水生态系统的生物区系不同,导致基准值也会存在差异.在综合研究美国、欧盟、加拿大、荷兰、澳大利亚和新西兰等国家和地区在推导水生生物水质基准的物种选择及其考虑因素的基础上,初步研究我国水生生物水质基准推导的物种选择原则.结果表明:推导我国水生生物水质基准需要选择来自8科的水生生物,分别为鲤科鱼类、硬骨鱼纲中的另一科、两栖动物纲的一科、浮游动物中节肢动物门和轮虫动物门各一科、底栖动物中节肢动物门和环节动物门各一科及一种最敏感的大型水生植物(或浮游植物),可全面代表我国水生态系统不同的营养级和生命形式. 相似文献
400.
正定矩阵因子分解法(PMF)是目前国内外PM2.5源解析研究中应用最为广泛的受体模型之一,但传统PMF源解析方法大多数是基于硝酸盐、硫酸盐和元素碳等无机组分,源示踪性较弱,难以精细化解析大气PM2.5来源. 基于PM2.5中主要化学组分、痕量元素以及有机分子示踪物在线观测数据,采用PMF受体模型,全面对比了基于无机化学组分传统源解析方法(MCC)与基于有机分子示踪物源解析方法(OMM)在源类识别、源谱分离以及源贡献定量方面的差异. 结果表明,OMM方法对PM2.5来源解析的精细和精准程度有明显提升. 源识别方面,OMM方法通过输入多环芳烃、脂肪酸、二羧酸、羟基羧酸、C9酸和邻-苯二甲酸等有机分子示踪物,在MCC方法获得的工业源、船舶排放源、扬尘源、移动源、生物质燃烧源、二次硝酸盐和二次硫酸盐这7类源因子基础上,还解析获得了燃煤燃烧源、餐饮一次排放源以及4类二次有机气溶胶(SOA)源因子. 源谱分离方面,OMM方法能显著优化对不同燃烧排放源和SOA源的分离和识别,其解析获得的工业源、移动源、生物质燃烧源和燃煤燃烧源源谱特征与源排放实测结果较MCC方法更为吻合. 源贡献方面,MCC方法对移动源和生物质燃烧源贡献的定量总体高于OMM方法,尤其是当ρ(O3)较高(> 120 μg·m-3)时,MCC方法缺少有机分子示踪物的输入,无法较好地分离燃烧排放源和SOA源,导致解析获得的移动源和生物质燃烧源中包含了部分二次源贡献. 运用OMM方法,对亚运会前后杭州大气PM2.5来源变化开展进一步分析,发现会期移动源、工业源和扬尘源等一次源贡献较会前有明显下降,分别下降了65%、24%和24%,另外,由于挥发性有机物(VOCs)等前体物排放的削减,人为源SOA和高氧化态SOA源贡献在会期也有明显降低,分别降低了35%和49%,表明会期针对机动车排放、工业排放和工地扬尘等管控措施对于降低杭州PM2.5一次和二次生成有显著成效,揭示了有机分子示踪物在线观测数据对于精细化解析大气PM2.5来源、支撑下一阶段我国PM2.5污染精准防控的重要性. 相似文献