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71.
Through a comparative analysis of prices in capture fisheries and aquaculture sectors, the objectives of this paper are a) to investigate three the trends in prices of forage catches to feed the aquaculture species, b) to analyze the amount of fish species need to feed aquaculture species in order to assess the level of efficiency in resource use, and c) to examine the degree of economic concentration either in wild-catch industry and aquaculture sectors. The results show that prices of cultivated species are higher than prices of the same species when harvested from the sea. We explain this fact by the interplay of three forces. First, the amount of wild fish to feed aquaculture species continues to improve over time. Second, the pressure of fishing activities has not been reduced since catches of most forage fishes are declining, which induce higher prices of capture species that feed aquaculture production. Third, the level of seafood market concentration is significantly higher in aquaculture than in wild catches, which generates higher prices in aquaculture.  相似文献   
72.
为揭示城市水环境中前驱体对全氟烷基酸(PFAAs)输入特征、分布格局及健康风险的影响,对南京城市污水处理厂出水、河流、湖泊、长江饮用水源地等水体进行了考察.利用HPLC-MS/MS及总可氧化前驱体法(TOP Assay)分析了17种PFAAs与其总可氧化前驱体的污染特征,并通过推演耐受剂量评估了饮水途径的健康风险商(HQ).结果表明,污水处理厂出水中PFAAs浓度90.6~278ng/L,主要单体PFBS、PFHxA、PFOA占总浓度的63%;总可氧化前驱体浓度239~839pmol/L,PFBA前驱体含量最高.城市地表水中PFAAs浓度61.8~157ng/L,总可氧化前驱体浓度195~572pmol/L,PFBA、PFPe A、PFHxA3种全氟羧酸的前驱体含量最高,城市河流流经人口密集区后,PFAAs赋存浓度有所上升,但总可氧化前驱体浓度下降.饮用水源地中PFAAs浓度50.9~54.6ng/L,总可氧化前驱体浓度273~372pmol/L,以PFBA、PFPe A和PFHx A3种全氟羧酸的前驱体为主.相对高风险来源于PFOS的免疫毒性(HQ=0.024)以及PFOA的发育毒性...  相似文献   
73.
Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd‐infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post‐metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population‐level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events.  相似文献   
74.
Hibernating bats have undergone severe recent declines across the eastern United States, but the cause of these regional‐scale declines has not been systematically evaluated. We assessed the influence of white‐nose syndrome (an emerging bat disease caused by the fungus Pseudogymnoascus destructans, formerly Geomyces destructans) on large‐scale, long‐term population patterns in the little brown myotis (Myotis lucifugus), the northern myotis (Myotis septentrionalis), and the tricolored bat (Perimyotis subflavus). We modeled population trajectories for each species on the basis of an extensive data set of winter hibernacula counts of more than 1 million individual bats from a 4‐state region over 13 years and with data on locations of hibernacula and first detections of white‐nose syndrome at each hibernaculum. We used generalized additive mixed models to determine population change relative to expectations, that is, how population trajectories differed with a colony's infection status, how trajectories differed with distance from the point of introduction of white‐nose syndrome, and whether declines were concordant with first local observation of the disease. Population trajectories in all species met at least one of the 3 expectations, but none met all 3. Our results suggest, therefore, that white‐nose syndrome has affected regional populations differently than was previously understood and has not been the sole cause of declines. Specifically, our results suggest that in some areas and species, threats other than white‐nose syndrome are also contributing to population declines, declines linked to white‐nose syndrome have spread across large geographic areas with unexpected speed, and the disease or other threats led to declines in bat populations for years prior to disease detection. Effective conservation will require further research to mitigate impacts of white‐nose syndrome, renewed attention to other threats to bats, and improved surveillance efforts to ensure early detection of white‐nose syndrome.  相似文献   
75.
This article outlines some of the latest developments and opportunities for development finance institutions1 (DFIs) to become directly supportive of the Clean Development Mechanism (CDM2) in Africa. In striving to make development financing more environmentally friendly and sustainable, DFIs can play a key role in promoting the CDM on the African continent by providing monetary incentives through their project financing activities; encouraging and facilitating partnerships in support of sustainable development, particularly with reference to the CDM, and; providing technical advice and support to clients with regard to project design, planning and implementation. DFIs have traditionally focused on financing infrastructure and poverty alleviation projects. However, the emergence of the CDM has brought about a shift towards investments in services and products that reduce carbon dioxide emissions and encourage investments in environmentally friendly technologies. This can be ascribed in part to the development of a “carbon market” under the auspices of the Kyoto Protocol that took effect in February 2005. The carbon market and emerging carbon funds are some of the main drivers enabling DFIs to play an increasingly important role in promoting the CDM in Africa.  相似文献   
76.
This paper focuses on the linkages between water and trade policies, using Morocco as a case. This country is typical of many in that policy protects its import competing agricultural and industrial sectors while water in irrigated agriculture is priced below its marginal value product. Changing water policy without correcting for these other distortions leads to a more inefficient allocation of water. On the other hand, reforming trade policy alone can make farmers growing crops protected pre-reform worse off. Using an intertemporal, applied general equilibrium model, we find that trade reform actually creates an opportunity to pursue water policy reform. Creating a water user-rights market post trade reform not only compensates for the decline in farmers’ profits caused by the trade reform, but also raises the efficiency of water allocation and hence benefits the economy as a whole.  相似文献   
77.
随着新一轮科技革命和产业转型的发展,全球金属资源供需格局发生重大调整,美国、欧盟、日本等主要发达国家不断倒逼中国敞开优势金属供应。为保障国家金属资源安全,论文从可依赖性、可持续性、可承受性3个维度建立了一套金属资源供应风险评估体系,对中国优势金属供应全球需求的风险进行评估,结果表明:1)中国优势金属整体供应风险较高,铟、铋等两种金属风险值都在80以上,处于高风险水平;锑、锗、钡、镁、钨、稀土等6种金属风险值都是60~80之间,处于中高风险水平;镓、锶等两种金属处于中风险水平。2)在10种中国优势金属中,钡的可依赖性风险最高,达到81.88,稀土的风险最低,只有42.42。铟的可持续性风险最高,达到81.80;锑的最低,风险值为69.46。铟的可承受性风险也最高,高达100;铋的次之,风险值为89.23;钡的最低,只有33.96。3)随着未来新兴产业的快速发展,中国优势金属的供应风险将更加严峻。  相似文献   
78.
The regenerative capacity of ecosystems provides a regulatory basis for sustainable economic growth and development. A natural valuation of an ecosystem's services will arise in a market for developmental rights in the ecosystem using a unit of tradable 'right': E-Scrip. The amount of e-scrip needed for a development may be set by Environmental Assessment. The capacity of the ecosystem to regenerate with developmental pressure may be represented by an independent trader or Factor Proxy for the Environment who provides e-scrip to the market.  相似文献   
79.
为考察贵屿电子垃圾拆解区污染沿水体向下游的迁移行为和影响,本文对练江贵屿段及其上下游表层沉积物进行了系统采样和多溴联苯醚(PBDEs)分析,并对其污染来源和潜在生态风险进行了探讨.结果表明:PBDEs在练江上下游沉积物中普遍存在(检出率100%),在贵屿上游浓度较低(10.2~2120 ng·g-1),进入贵屿段急剧升高(7470~193000 ng·g-1),至贵屿下游后有所起伏但整体下降(734~11300 ng·g-1).练江的PBDEs污染主要来自于沿途排放,贵屿电子垃圾拆解业是其中最大的污染排放源.贵屿下游沉积物的PBDEs浓度比上游高约一个数量级,说明贵屿高浓度的PBDEs污染可沿水体迁移至下游.主因子分析结果表明练江沉积物中的PBDEs污染存在3种模式,上游和下游主要支流(贵屿支流除外)呈现Deca-BDE污染模式(BDE-209为绝对优势单体),这是我国沉积物中PBDEs的典型污染模式,可视为练江沉积物中PBDEs污染的背景模式;贵屿则呈现出两种特异模式:Penta-BDE模式(优势单体BDE-47&-99)和Deca-BDE脱溴降解模式(以BDE-197为主,其次是-209),这分别与贵屿地区的电路板拆解和塑料的高温处理方式(烘烤、焚烧、熔融等)有关;贵屿下游支流和主干道样品中的PBDEs呈现与贵屿相似但多种模式共存的特征,进一步证实贵屿的PBDEs污染已沿水体迁移至下游并影响其PBDEs组成特征.练江上游和下游主要支流(贵屿支流除外)PBDEs的风险商值(HQ)均<1,表明生态风险可接受;贵屿段PBDEs的HQ值均>1,最高达63.9,存在严重生态风险;受贵屿污染迁移影响,贵屿下游支流及部分练江主干道样品的HQ值也>1,为PBDEs污染高风险区;Penta-BDEs(三-五溴代BDEs)为HQ值主要贡献污染物,其次是Hexa-BDEs和Deca-BDE.鉴于PBDEs具有环境持久性且在贵屿段的沉积通量高达(477±648)t(贵屿下游为(152±169)t),其在贵屿及其下游20 km以内的污染急需开展进一步调查并采取相应的污染治理和修复措施.  相似文献   
80.
In December 2010, the German government increased the maximum ethanol content that can be blended with petrol from 5% to 10%, which facilitated the introduction of the ethanol–petrol blend E10. The revised ethanol–petrol blend was introduced with ambitions towards decarbonizing the transport sector as well as to support energy security and rural development. While usually supportive of actions aimed to combat climate change, the great majority of German motorists have refused to buy E10. The lacking demand for E10 is the empirical phenomenon addressed by this study. How did the fuel suppliers comply with the policy provisions? Which actors made attempts to influence the motorists’ demand for the new ethanol–petrol blend? Which actor was assigned the responsibility for the problems that occurred upon the rollout of the new fuel type? These research questions guide this study, which concentrates on the behaviour of transport fuel suppliers and consumers in mandated markets, that is, markets created by policy provisions.  相似文献   
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