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   220篇
  免费   0篇
  国内免费   1篇
废物处理   15篇
环保管理   15篇
综合类   93篇
基础理论   27篇
污染及防治   49篇
评价与监测   13篇
社会与环境   9篇
  2020年   2篇
  2018年   6篇
  2017年   3篇
  2015年   4篇
  2014年   8篇
  2013年   6篇
  2012年   6篇
  2011年   7篇
  2010年   8篇
  2009年   6篇
  2008年   14篇
  2007年   13篇
  2006年   9篇
  2005年   5篇
  2004年   13篇
  2003年   4篇
  2002年   9篇
  2001年   2篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   5篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1988年   2篇
  1983年   3篇
  1978年   2篇
  1966年   3篇
  1965年   2篇
  1964年   4篇
  1961年   5篇
  1960年   3篇
  1959年   6篇
  1957年   4篇
  1956年   1篇
  1955年   3篇
  1954年   3篇
  1953年   1篇
  1952年   4篇
  1950年   3篇
  1948年   2篇
  1942年   1篇
  1941年   1篇
  1933年   1篇
  1931年   1篇
  1920年   1篇
  1915年   1篇
排序方式: 共有221条查询结果,搜索用时 140 毫秒
41.
Fertilization by phosphorus and also nitrogen fertilizers are the main source of cadmium soil contamination. Cadmium is relatively easily taken up by plants and then consequently enters their food chain. We investigated whether the cultivation medium with or without sulphates supplement affects the synthesis of protective low molecular mass thiols such as cysteine, reduced glutathione, oxidized glutathione and phytochelatins (PC2) in Dionaea muscipula treated with cadmium(II) ions at 0, 1, 5, 10, 25, 50, 100, 250, 500 and 1,000 μM for 6 weeks. The plants cultivated in the presence of sulphates showed higher cadmium tolerance due to faster growth and lesser number of necrosis hallmarks. Further, we utilized liquid chromatography with electrochemical detection for determination of the thiols in plant tissues. In the case of the plants cultivated on media supplemented with sulphates for 6 weeks the average PC2 level was 2,830 ng/g of fresh weight (FW). However, the plants cultivated on media without the presence of sulphates on average contained 1,160 ng PC2/g FW. Results obtained showed the positive effect of sulphur supplementation in cadmium detoxification processes in plants. In addition to thiol content, we also determined level of majority secondary metabolite of Venus flytrap, naphthoquinone plumbagin. Generally, the presence of sulphates in the media enhanced the protective mechanism and did not affect directly the synthesis of secondary metabolite plumbagin.  相似文献   
42.
The paper describes the design and implementation of a plant biodiversity conservation program that was developed under funding and time constraints for diverse ecological, social, and institutional environments. The biodiversity program for alpine meadows and pastures located in the Swiss Canton of the Grisons is used as an example. The design of the sustainable program relied on existing legislation, accounted for limited ecological knowledge and expertise, and considered biodiversity as a common-pool resource. The trend to intensified cultivation of restricted areas required fast action, while the sustainability of the program design had to take into account institutional diversity. Fifteen habitats and plant communities worth conserving were known, and 57 plant species were identified as indicator species for establishing an inventory and for monitoring purposes. A small subset of 16 well known plant species was presented to the farming communities. They were invited to notify the areas in which they observed the presence of these plants. In different regions of the Canton a total number of 39 paraecologists were trained to inspect the areas notified by farmers and to recommend possible incorporation into the Cantonal inventory. This was done once the farmers signed a contract in which they agreed to follow adequate management practices. The farmers received subsidies to compensate for their losses. Communal authorities controlled the fertilizer input and cutting dates, while the paraecologists were trained to monitor plant biodiversity. The program started in 1992 and the initial phase of the inventory was terminated in 1996. At the beginning of 1996, an inventory of 2617.19 ha, most of which are meadows, was taken and managed according to the rules specified in the contract. The program was considered successful because (i) of the size of the area in the inventory, (ii) about 30%of the farmers participated, and (iii) farmers started cultivating previously abandoned farmland.  相似文献   
43.
Environment, Development and Sustainability - The most common drinking water clarification technology worldwide is based on precipitation using the floccules of iron(III) oxide-hydroxide FeO(OH)....  相似文献   
44.
45.
46.
47.
Waste and process gases from thermal power and metallurgical plants or such products from alkali-chloride industries contain metallic, inorganic and organic mercury. Widespread processes applied to remove the greatest amount of mercury are absorption and adsorption. Caused by the lowering of the emission limit from 200 to 50 μg/m3 [STP] by national and European legislators, considerable efforts have been made to enhance the efficiency of the main separation units of flue gas cleaning plants by applying the appropriate technological measures. This article is focused on the removal of mercury from waste gases. The state of engineering is described, especially with regard to enhancing the efficiency of separation in the raw gas, in wet, dry and quasi-dry processes as well as in tail-end process units. Specially impregnated ceramic carriers can be used for the selective separation of metallic, inorganic and organic mercury. Amalgamation has been investigated as a possible separation mechanism both experimentally and in theory. Using the ceramic reactor, removal rates for gaseous mercury and its compounds can be achieved which are even lower than 50 μg/m3 [STP]. The technology, the separation mechanisms and the ecological advantages through the use of ceramic reactors are presented in the article as well.  相似文献   
48.
A field study of triclosan loss rates in river water (Cibolo Creek, TX)   总被引:1,自引:0,他引:1  
Triclosan (TCS) is an anti-microbial agent used in down-the-drain consumer products. Following sewage treatment some of the triclosan will enter receiving waters. This study was designed to determine the die-away rate of triclosan released into a river as part of the sewage treatment plant effluent matrix. The study was conducted in Cibolo Creek, a moderate sized stream (discharge approximately 0.1 m(3)s(-1)) located in South Central Texas. Triclosan was analyzed from samples collected upstream of the sewage treatment plant, the sewage treatment plant effluent, and the river downstream from the effluent discharge. The first-order loss rate of parent triclosan from the water column was calculated from measured data (0.06 h(-1)) and this rate corresponded to a 76% reduction in triclosan over an 8 km river reach below the discharge. Mathematical modeling indicated that sorption and settling accounted for approximately 19% of total triclosan loss over 8 km. When removing sorption and settling, the remaining amount of triclosan had an estimated first-order loss rate of 0.25 h(-1). This loss rate was presumably due to other processes such as biodegradation and photolysis. These data show that loss of parent triclosan from the water column is rapid. Additional data are needed to fully document loss mechanisms.  相似文献   
49.
Zusammenfassung  Bei einer genauen Kenntnis der vorliegenden Quecksilberverbindungen und ihrem Verhalten im Rauchgaspfad thermischer Anlagen k?nnen durch entsprechende technische Ma?nahmen die Abscheideeffizienzen in trockenen, quasitrockenen und nassen Rauchgasreinigungsanlagen erheblich gesteigert werden, so da? der derzeit gesetzlich vorgeschriebene Emissionsgrenzwert von 50 μg/m3 [i.N.tr.] eingehalten und unterschritten wird. Die in den letzten Jahren unternommenen Aktivit?ten und Fortschritte bei der Reduzierung des Quecksilberaussto?es von thermischen Anlagen werden zusammenfassend dargestellt. Am Beispiel von tr?gerimmobilisierten metall- und/oder metallsalzpartikelbelegten Tr?germaterialien (G/S-Reaktoren) wird die selektive Entfernung des Quecksilbers bzw. dessen Verbindungen experimentell und theoretisch im Rauchgaspfad verdeutlicht. Aus der selektiven Abtrennung von Quecksilber und seinen Verbindungen in der Gasphase resultieren auch entsprechende ?kologische und ?konomische Vorteile, die den allgemein erkennbaren Trend der artspezifischen Abtrennung von Schadstoffen mit einer m?glichen Rückführung des Wertstoffes Quecksilber in den Wirtschaftskreislauf unterstützen.   相似文献   
50.
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