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491.
Strategies to overcome barriers to the development of sustainable agriculture in Canada: The role of agribusiness 总被引:1,自引:0,他引:1
R. J. Macrae J. Henning S. B. Hill 《Journal of Agricultural and Environmental Ethics》1993,6(1):21-51
Strategies to involve agribusiness in the development of sustainable agricultural systems have been limited by the lack of a comprehensive conceptual framework for identifying the most critical supportive policies, programs and regulations. In this paper, we propose an efficiency/substitution/redesign framework to categorize strategies for modifying agribusiness practices. This framework is then used to identify a diverse range of short, medium, and long-term strategies to be pursued by governments, community groups, academics and agribusiness to support the transition. Strategies discussed include corporate greening, ethical investment, changing the legal status of the corporaton, new business forms and the development of ecological economics. 相似文献
492.
本文根据沱江源头水源涵养林辽度砍代,导致源头蓄水量锐减,以及滥采乱控矿石,造成资源损失与灾害频繁的严峻现实,提出了建立沱江源头水源保护区的必要性。 相似文献
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The oxidative degradation of polyolefins in the presence of transition metal catalysts is well known in the patent and technical literature. It has been suggested that a properly designed oxidatively degradable polymer could be used in limited lifetime articles and also on those whose primary method of disposal is composting, wherein the thermal activity is used to accelerate the oxidation process. The results of a detailed study of transition metal reactivity in the presence of numerous oxidation promoting species in polyolefins are presented. The oxidative degradation of these polyolefins was demonstrated at moderate temperatures under air and in a simulated compost environment. Approaches to determining the ultimate fate of these materials are discussed. 相似文献
495.
Lawrence M. Magura Darrel E. Wood 《Journal of the American Water Resources Association》1980,16(1):56-62
ABSTRACT: Recognition of the flood hazard that exists on alluvial fans has seriously lagged behind the recognition of other more conventional flood hazards such as those associated with most rivers. This delay in recognition was due, until recently, to a general lack of economic investment and development in these areas and a concomitant lack of historical alluvial fan flood damage. Dramatic recent events, such as Tropical Storm Kathleen, emphasized to the Federal Insurance Administration (FIA) the need for developing an appropriate methodology to identify flood hazard areas on alluvial fans. This paper presents the methodology now employed by FIA as well as flood plain management considerations that could reduce future flood related damage to communities developing in these areas. 相似文献
496.
Kenneth E. Bencala Ronald E. Rathbun Alan P. Jackman Vance C. Kennedy Gary W. Zellweger Ronald J. Avanzino 《Journal of the American Water Resources Association》1983,19(6):943-950
ABSTRACT: A significant fraction of rhodamine WT dye was lost during a short term multitracer injection experiment in a mountain stream environment. The conservative anion chloride and the sorbing cation lithium were concurrently injected. In-stream rhodamine WT concentrations were as low as 45 percent of that expected, based on chloride data. Concentration data were available from shallow‘wells’dug near the stream course and from a seep of suspected return flow. Both rhodamine WT dye and lithium were nonconservative with respect to the conservative chloride, with rhodamine WT dye closely following the behavior of the sorbing lithium. Nonsorption and sorption mechanisms for rhodamine WT loss in a mountain stream were evaluated in laboratory experiments. Experiments evaluating nonsorption losses indicated minimal losses by such mechanisms. Laboratory experiments using sand and gravel size streambed sediments show an appreciable capacity for rhodamine WT sorption. The detection of tracers in the shallow wells and seep indicates interaction between the stream and the flow in the surrounding subsurface, intergravel water, system. The injected tracers had ample opportunity for intimate contact with materials shown in the laboratory experiments to be potentially sorptive. It is suggested that in the study stream system, interaction with streambed gravel was a significant mechanism for the attenuation of rhodamine WT dye (relative to chloride). 相似文献
497.
Burchard H. Heede 《Journal of the American Water Resources Association》1972,8(3):523-530
ABSTRACT The influence of a forest on the formation of steps in two small streams of the Colorado Rocky Mountains was studied. Steps provided by logs fallen across the channel added to flow energy reduction. The streams required additional gravel bars to adjust to slope. Average step length between logs and gravel bars was strongly related to channel gradient and median bed material size. Based on the average number of log steps per 50 feet of channel, an average of 116 percent of gravel bars were added at Fool Creek and 60 percent at Deadhorse Creek. The latter had 52 percent more logs in the channel and therefore required less bed material movement than the former. Although these are “rushing mountain streams,” most flow velocities ranged between 0.5 and 2.5 f.p.s. Exponents of a function relating rate of change of depth or velocity to discharge indicated that dynamic stream equilibrium was attained. Implications for forest management are that sanitation cuts (removal of dead and dying trees) would not be permissible where a stream is in dynamic equilibrium and bed material movement should be minimized. 相似文献
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