首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3145篇
  免费   85篇
  国内免费   78篇
安全科学   115篇
废物处理   23篇
环保管理   1209篇
综合类   1115篇
基础理论   196篇
环境理论   1篇
污染及防治   34篇
评价与监测   34篇
社会与环境   538篇
灾害及防治   43篇
  2023年   16篇
  2022年   42篇
  2021年   54篇
  2020年   54篇
  2019年   46篇
  2018年   48篇
  2017年   76篇
  2016年   85篇
  2015年   65篇
  2014年   75篇
  2013年   122篇
  2012年   132篇
  2011年   172篇
  2010年   122篇
  2009年   97篇
  2008年   107篇
  2007年   165篇
  2006年   141篇
  2005年   165篇
  2004年   171篇
  2003年   153篇
  2002年   127篇
  2001年   91篇
  2000年   136篇
  1999年   145篇
  1998年   87篇
  1997年   76篇
  1996年   63篇
  1995年   71篇
  1994年   52篇
  1993年   55篇
  1992年   50篇
  1991年   36篇
  1990年   25篇
  1989年   9篇
  1988年   14篇
  1986年   8篇
  1985年   9篇
  1984年   8篇
  1983年   8篇
  1981年   8篇
  1980年   12篇
  1979年   12篇
  1978年   10篇
  1977年   12篇
  1975年   8篇
  1974年   7篇
  1973年   11篇
  1972年   9篇
  1971年   15篇
排序方式: 共有3308条查询结果,搜索用时 31 毫秒
121.
ABSTRACT: Long term data on surface water quality can sometimes be assembled by combining data collected by different agencies at different times and assuming that between agency differences in data quality are insignificant. The objective of this paper was to assess the quality of riverine nitrate (NO3) concentrations in Illinois measured and reported by four agencies from 1967 to 1974 by comparing median values for similar sampling locations and periods. A total of 17 river reaches were identified for which two agencies reported NO3 concentrations during similar periods. Nonparametric comparison of median values and analysis of covariance with discharge as a covariant produced similar results. Nitrate concentrations reported by the U.S. Geological Survey (USGS) from 1967 to 1971 were not statistically (P > 0.05) different from values reported by the Illinois State Water Survey (ISWS) for two of three river reaches. Additionally, NO3 concentrations reported by USGS from 1972 to 1974 were not statistically different than concentrations reported by the Illinois Environmental Protection Agency (IEPA) for four of five river reaches. From 1969 to 1971, NO3 concentrations reported by the Illinois Department of Public Heath and the Illinois Environmental Protection Agency (IDPH/IEPA) were less than one‐fourth the magnitude of values reported by ISWS. The median NO3 concentrations measured by the Central Illinois Public Service (CIPS) were significantly greater than those measured by USGS and IDPH/IEPA in the three comparable sampling locations. The use of NO3 concentrations measured by CIPS and IDPH/IEPA prior to 1972 is not recommended.  相似文献   
122.
ABSTRACT: Increasing demands on western water are causing a mounting need for the conjunctive management of surface water and ground water resources. Under western water law, the senior water rights holder has priority over the junior water rights holder in times of water shortage. Water managers have been reluctant to conjunctively manage surface water and ground water resources because of the difficulty of quantification of the impacts to surface water resources from ground water stresses. Impacts from ground water use can take years to propagate through an aquifer system. Prediction of the degree of impact to surface water resources over time and the spatial distribution of impacts is very difficult. Response functions mathematically describe the relationship between a unit ground water stress applied at a specific location and stream depletion or aquifer water level change elsewhere in the system. Response functions can be used to help quantify the spatial and temporal impacts to surface water resources caused by ground water pumping. This paper describes the theory of response functions and presents an application of transient response functions in the Snake River Plain, Idaho. Transient response functions can be used to facilitate the conjunctive management of surface and ground water not only in the eastern Snake River Plain basin, but also in similar basins throughout the western United States.  相似文献   
123.
铅锌矿产资源开发重金属污染风险评价   总被引:3,自引:0,他引:3  
在论述环境风险评价的概念、理论和方法的基础上,通过对某典型铅锌矿山重金属污染程度、重金属毒性响应系数和生态危害系数的计算与探讨,建立了铅锌矿山重金属生态风险评价指标体系.根据所建立的指标体系,计算了每个样点的生态风险指数,结果认为该矿山总体环境质量很差,重金属污染极其严重.  相似文献   
124.
作物秸秆资源的利用对提高食物安全,减轻环境污染,促进农业可持续发展具有重要意义.通过对农户的调查,分析了山西省夏县的秸秆利用途径,对该县秸秆利用现状进行了评价,并分析了造成这种现状的原因.结果表明,夏县作为典型的"小麦-玉米"二熟农作区,秸秆利用效率较高,其中小麦秸秆主要用于工业原料、饲料和还田,玉米秸秆则主要用于饲料和弃置堆放.这种利用方式与造纸业发展、传统的牲畜饲喂方式、农业机械化发展和气候特点有关.最后提出了进一步高效利用秸秆资源的建议.  相似文献   
125.
基于矿泉水与人体健康的关系、在社会经济发展中的作用,以及对梅州市矿泉水资源条件及其开发利用现状的调研,探讨了经济欠发达山区矿泉水资源的开发利用对策和前景.认为应统一资源管理,加强质量监督力度,打造优质品牌,提高市场竞争能力,争取与食品、旅游等部门联营,使矿泉水产品多样化、系列化;结合地方工业建设和梅州旅游市场需求,培育矿泉水消费市场.  相似文献   
126.
发展旅游对海岛环境的影响及应对策略研究   总被引:3,自引:0,他引:3  
孔海燕 《四川环境》2005,24(3):22-24
海岛作为一个独特的地理单元,旅游资源丰富,发展前景广阔,但在海岛旅游迅速发展的同时,海岛环境也受到极大的影响。而海岛又是环境敏感地区,生态环境脆弱,一旦破坏就难以恢复,所以重视海岛旅游出现的环境问题,加强对海岛环境的保护,促进海岛经济的可持续发展应引起广泛的关注和重视。  相似文献   
127.
One of the most important endemic tree species of Chile and at the same time one of the most endangered ones is Araucaria araucana (Mol.) C. Koch, the monkey‐puzzle tree. It grows in the Andes Mountains, homeland of the indigenous Mapuche Pewenche people who depend on this tree. This paper is based on field research that investigated the ecological knowledge, uses and management of the Araucaria araucana forest by indigenous Mapuche Pewenche people based on the socio‐cultural, spiritual and ecological relationships they have with the Araucaria forest, to find out how indigenous people and their knowledge could contribute to sustainable Araucaria forest management. A Mapuche Pewenche community located in the IX region of Chile contributed to this study. Based on the analyses this paper illustrates the nature of indigenous ecological knowledge of Araucaria araucana on the one hand, and its utility in native forest management on the other. The research shows that the Mapuche Pewenche hold ecological knowledge and conduct practices to manage their Araucaria forest in a balanced way. They conserve and use forest biodiversity at one and the same time. This paper provides recommendations for sustainable Araucaria forest management and conservation strategies ex‐situ and in‐situ incorporating indigenous knowledge and scientific knowledge and for promoting a collaborative natural resources management.  相似文献   
128.
Since the first product became commercially available in 1995, biotechnology has become the fastest growing crop technology, dominating large shares of the global agricultural market. The development of biotechnology, however, has given rise to questions regarding human and ecological safety, culminating in local and global political battles. While researchers interested in biotech politics have focused on areas such as media framing, social movements, and campaign work, less attention has been paid to how the industry has historically promoted and legitimized this swift proliferation. In this study, we conduct a discourse analysis of documents available on live and archived websites to discern the legitimation strategies employed by one important corporate actor, Monsanto. Findings show that for nearly two decades, Monsanto consistently employed discursive resources that concealed details about actors and action, reflected trends among experts in global sustainability discourse, and reshaped narratives to promote itself, products, and biotechnology in general.  相似文献   
129.
《组织行为杂志》2017,38(8):1213-1226
This diary study examined within‐person effects of positive work and off‐work experiences on daily work engagement. Assessing the gain cycle assumption of conservation of resources theory, we investigated the relationship of nighttime recovery experiences and subsequent resources including elevated sleep quality and morning positive affect; the relationship of morning positive affect with positive collegial interactions and subsequent work engagement; and the relationship of work engagement with nighttime recovery experiences. Sixty‐nine employees completed 3 daily questionnaires over 5 consecutive working days. Multilevel analyses revealed that sleep quality positively predicted morning positive affect, which in turn predicted work engagement directly and also indirectly through having positive interactions with colleagues. Work engagement positively predicted nighttime recovery experiences, whereas nighttime recovery experiences were not related to sleep quality or morning positive affect the next day. Overall, on days after a good night's sleep, individuals feel more positive, bring this positivity to their workplace, reach out to their workplace colleagues, and are in turn more likely to be engaged in their work. Additionally, on days when individuals experience higher levels of positive collegial interactions at work and in turn higher work engagement, they are likely to enjoy better recovery experiences.  相似文献   
130.
西安市建筑垃圾渣土资源再利用研究   总被引:4,自引:4,他引:0       下载免费PDF全文
张利军 《环境工程》2017,35(5):122-124
建筑垃圾渣土作为"建筑副产品",已造成严重的城市环境问题。通过对西安市建筑垃圾渣土的现场调查及工程再利用,借鉴发达国家及国内省市建筑垃圾渣土的成功管理经验和资源再利用的成功范例,提出了西安建筑垃圾资源再利用的对策建议,对"十三五"期间减少已有建筑垃圾的存量并遏制增量和建设西安森林城市具有参考意义。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号