全文获取类型
收费全文 | 5446篇 |
免费 | 429篇 |
国内免费 | 421篇 |
专业分类
安全科学 | 1105篇 |
废物处理 | 72篇 |
环保管理 | 1004篇 |
综合类 | 2221篇 |
基础理论 | 496篇 |
环境理论 | 1篇 |
污染及防治 | 121篇 |
评价与监测 | 264篇 |
社会与环境 | 711篇 |
灾害及防治 | 301篇 |
出版年
2024年 | 16篇 |
2023年 | 76篇 |
2022年 | 106篇 |
2021年 | 173篇 |
2020年 | 177篇 |
2019年 | 135篇 |
2018年 | 110篇 |
2017年 | 230篇 |
2016年 | 259篇 |
2015年 | 234篇 |
2014年 | 238篇 |
2013年 | 330篇 |
2012年 | 467篇 |
2011年 | 529篇 |
2010年 | 381篇 |
2009年 | 297篇 |
2008年 | 223篇 |
2007年 | 317篇 |
2006年 | 336篇 |
2005年 | 258篇 |
2004年 | 203篇 |
2003年 | 175篇 |
2002年 | 138篇 |
2001年 | 107篇 |
2000年 | 102篇 |
1999年 | 83篇 |
1998年 | 86篇 |
1997年 | 65篇 |
1996年 | 61篇 |
1995年 | 64篇 |
1994年 | 42篇 |
1993年 | 45篇 |
1992年 | 42篇 |
1991年 | 23篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有6296条查询结果,搜索用时 15 毫秒
181.
针对目前我国民用运输机场航空器场内失事应急救援综合演练缺乏有效评估体系的现状,通过对演练过程进行系统分析,构建航空器场内失事应急救援演练评估指标体系,涵盖消防、医疗、公安、媒体应对、运行指挥中心、地服、飞行区7个组织部门的2级指标。结合航空器场内失事救援的业务特点以及指标体系内在逻辑,设计相应的评估方法,对开展的航空器场内失事应急演练进行评估;最后,以国内2个机场的相关应急演练过程为典型示例,进行应用分析。研究结果表明:构建的演练评估指标体系及评估方法能较好地应用于实际应急演练过程,进而在演练评估结果和建议的基础上,实现应急演练的持续改进。 相似文献
182.
Martin Drechsler Henrik G. Smith Astrid Sturm Frank Wätzold 《Conservation biology》2016,30(4):894-899
Payments to compensate landowners for carrying out costly land‐use measures that benefit endangered biodiversity have become an important policy instrument. When designing such payments, it is important to take into account that spatially connected habitats are more valuable for many species than isolated ones. One way to incentivize provision of connected habitats is to offer landowners an agglomeration bonus, that is, a bonus on top of payments they are receiving to conserve land if the land is spatially connected. Researchers have compared the cost‐effectiveness of the agglomeration bonus with 2 alternatives: an all‐or‐nothing, agglomeration payment, where landowners receive a payment only if the conserved land parcels have a certain level of spatial connectivity, and a spatially homogeneous payment, where landowners receive a payment for conserved land parcels irrespective of their location. Their results show the agglomeration bonus is rarely the most cost‐effective option, and when it is, it is only slightly better than one of the alternatives. This suggests that the agglomeration bonus should not be given priority as a policy design option. However, this finding is based on consideration of only 1 species. We examined whether the same applied to 2 species, one for which the homogeneous payment is best and the other for which the agglomeration payment is most cost‐effective. We modified a published conceptual model so that we were able to assess the cost‐effectiveness of payment schemes for 2 species and applied it to a grassland bird and a grassland butterfly in Germany that require the same habitat but have different spatial‐connectivity needs. When conserving both species, the agglomeration bonus was more cost‐effective than the agglomeration and the homogeneous payment; thus, we showed that as a policy the agglomeration bonus is a useful conservation‐payment option. 相似文献
183.
Georgia Mavrommati Kostas Bithas Mark E. Borsuk Richard B. Howarth 《Conservation biology》2016,30(6):1173-1181
In the Anthropocene, coupled human and natural systems dominate and only a few natural systems remain relatively unaffected by human influence. On the one hand, conservation criteria based on areas of minimal human impact are not relevant to much of the biosphere. On the other hand, conservation criteria based on economic factors are problematic with respect to their ability to arrive at operational indicators of well‐being that can be applied in practice over multiple generations. Coupled human and natural systems are subject to economic development which, under current management structures, tends to affect natural systems and cross planetary boundaries. Hence, designing and applying conservation criteria applicable in real‐world systems where human and natural systems need to interact and sustainably coexist is essential. By recognizing the criticality of satisfying basic needs as well as the great uncertainty over the needs and preferences of future generations, we sought to incorporate conservation criteria based on minimal human impact into economic evaluation. These criteria require the conservation of environmental conditions such that the opportunity for intergenerational welfare optimization is maintained. Toward this end, we propose the integration of ecological–biological thresholds into decision making and use as an example the planetary‐boundaries approach. Both conservation scientists and economists must be involved in defining operational ecological–biological thresholds that can be incorporated into economic thinking and reflect the objectives of conservation, sustainability, and intergenerational welfare optimization. 相似文献
184.
JONATHAN M. JESCHKE SVEN BACHER TIM M. BLACKBURN JAIMIE T. A. DICK FRANZ ESSL THOMAS EVANS MIRIJAM GAERTNER PHILIP E. HULME INGOLF KÜHN AGATA MRUGAŁA JAN PERGL PETR PYŠEK WOLFGANG RABITSCH ANTHONY RICCIARDI DAVID M. RICHARDSON AGNIESZKA SENDEK MONTSERRAT VILÀ MARTEN WINTER SABRINA KUMSCHICK 《Conservation biology》2014,28(5):1188-1194
Non‐native species cause changes in the ecosystems to which they are introduced. These changes, or some of them, are usually termed impacts; they can be manifold and potentially damaging to ecosystems and biodiversity. However, the impacts of most non‐native species are poorly understood, and a synthesis of available information is being hindered because authors often do not clearly define impact. We argue that explicitly defining the impact of non‐native species will promote progress toward a better understanding of the implications of changes to biodiversity and ecosystems caused by non‐native species; help disentangle which aspects of scientific debates about non‐native species are due to disparate definitions and which represent true scientific discord; and improve communication between scientists from different research disciplines and between scientists, managers, and policy makers. For these reasons and based on examples from the literature, we devised seven key questions that fall into 4 categories: directionality, classification and measurement, ecological or socio‐economic changes, and scale. These questions should help in formulating clear and practical definitions of impact to suit specific scientific, stakeholder, or legislative contexts. Definiendo el Impacto de las Especies No‐Nativas 相似文献
185.
186.
制革废水和印染废水的综合毒性评估及鉴别 总被引:3,自引:3,他引:0
研究采用成组生物毒性试验(发光菌急性毒性、斑马鱼幼鱼急性毒性,斑马鱼胚胎发育毒性和小球藻急性毒性),结合理化指标,通过毒性单位、平均毒性(average toxicity,Av Tx)、毒性指数(toxic print,Tx Pr)、最敏感的测试(most sensitive test,MST)和潜在毒性效应指数(potential ecotoxic effects probe,PEEP)对不同工艺阶段印染及制革废水进行毒性削减评估.结果表明PEEP能兼顾废水排放量与毒性效应,更为客观地表征了废水综合毒性,PEEP评价结果显示制革废水和印染废水的毒性削减率分别达到36.8%和23.2%.最后,以发光菌作为受试生物,采用毒性鉴别评估(toxicity identification evaluation,TIE)技术,对印染废水进行毒性鉴别.结果表明,印染废水中主要的致毒物质为非极性有机污染,其次为可滤性化合物,然后是重金属、氧化性物质以及挥发性物质. 相似文献
187.
典型生活垃圾处理设施恶臭排放特征及污染评价 总被引:1,自引:1,他引:0
为研究生活垃圾处理设施恶臭污染排放特征,分别在北京市生活垃圾填埋、焚烧、堆肥3种工艺的前处理车间采集恶臭样品,利用冷阱富集-气质联用(GC/MS)技术对恶臭气体进行分析.结果表明,检测到的恶臭物质主要分为6大类:芳香烃化合物、硫化物、卤代物、烯烃、烷烃和含氧有机物.其中,填埋工艺的前处理车间共检测出50种物质,质量浓度为100.069mg·m~(-3),理论臭气浓度OU_T为350.611,综合臭气指数N为25.448.焚烧工艺的前处理车间共检测出55种物质,质量浓度为36.052 mg·m~(-3),理论臭气浓度OU_T为141.434,综合臭气指数N为21.506.堆肥工艺的前处理车间共检测出34种物质,质量浓度为25.382 mg·m~(-3),理论臭气浓度OU_T为27.547,综合臭气指数N为14.401.利用阈稀释倍数的恶臭贡献值计算方法,初步识别填埋工艺的前处理车间特征恶臭污染物质为:二甲二硫醚、乙酸丁酯、对二乙苯和乙醇;焚烧工艺的前处理车间特征恶臭污染物质为:甲硫醇、二甲二硫醚、乙醇和柠檬烯;堆肥工艺的前处理车间特征恶臭污染物质为:乙醇、二甲二硫醚、乙酸丁酯和柠檬烯. 相似文献
188.
以2014—2015年双台子河口滨海湿地植被修复20个站位调查资料为基础,对湿地修复结构指标、功能指标和环境指标进行研究,结合湿地生态系统健康理论,构建湿地生态环境健康评价指标体系。运用层次分析法(AHP)确定权重,对各个指标赋予权重,将健康评价分为3个等级,确立了生态健康评价方法,对近岸破损湿地翅碱蓬修复生境进行评价。进一步引用评价净影响值(EI)方法判断生境修复前、后的健康对比状态,从而确定翅碱蓬对该破损湿地的修复效果显著。从景观生态学和健康评价角度分析来看,建立此评价方法是可行的,可为今后湿地的管理与保护提供科学依据。 相似文献
189.
基于可持续发展基本理论,选取60项指标建立陕北地区可持续发展评价指标体系,采用软件SPSS(19.0)进行主成分分析,分别对延安市、榆林市2000—2014年的可持续发展水平、可持续发展潜力和可持续发展协调度进行动态对比分析。结果表明延安市、榆林市发展基本趋于一致:可持续发展水平较高,但可持续发展潜力明显不足,可持续发展协调度较低;制约其可持续发展的主要因素在于资源发展动力不足、产业结构单一、环境的恶化及治理的低效。 相似文献
190.
我国京津冀地区近年频遭大气PM2.5污染侵扰,相关研究表明,既使关闭建筑外窗,大气中PM2.5仍可以通过渗透通风方式进入室内污染环境.为定量评价建筑渗透通风及无室内污染源条件下建筑结构(如外窗缝隙结构、房间建筑结构等)对室内ρ(PM2.5)的影响规律,基于北京市东城区、朝阳区6个不同建筑结构的房间室内外ρ(PM2.5)实时监测数据,重点比较分析了建筑结构对室内外ρ(PM2.5)关联特性的影响规律.此外,根据颗粒物穿透特性及沉降特性机理,提出了反映建筑外窗缝隙结构(如缝高、缝深)的无量纲特征参数AP与反映房间建筑结构(如层高、开间、进深)的无量纲特征参数Ak.在前期提出的室内ρ(PM2.5)预测模型基础上,进一步构建了二者(AP与Ak)对室内ρ(PM2.5)影响的评价模型,并通过实测数据验证了模型的正确性.结果表明:当室外PM2.5污染程度与气象条件一定时,建筑结构对I/O[室内外ρ(PM2.5)之比]影响较大,其范围在0.4~0.7之间;随着建筑外窗气密性等级的提高,对应室内ρ(PM2.5)呈显著的下降趋势.建筑外窗缝隙结构对室内ρ(PM2.5)影响程度远大于房间建筑结构,敏感性分析结果表明,当建筑外窗缝高每降低50%或缝深每提高50%,对应室内ρ(PM2.5)约可下降33.6%与31.9%.研究显示,气密性等级较高的建筑外窗缝隙缝高往往较小、缝深较长,渗透通风条件下对控制室内ρ(PM2.5)水平作用更显著。 相似文献