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111.
This article presents a review of major empirical research on environmental justice. Forty-two empirical research studies spanning three decades were evaluated and categorized on the basis of how well they meet reasonable scientific standards. Twelve of those studies are described and critiqued in detail, and an overview of trends in the literature is presented. The author concludes that the empirical foundations of environmental justice are so underdeveloped that little can be said with scientific authority regarding the existence of geographical patterns of disproportionate distributions and their health effects on minority, low-income, and other disadvantaged communities. If environmental managers and policy-makers do not recognize the high levels of empirical uncertainty surrounding the issue, they are apt to attribute an empirically unwarranted level of concreteness to the empirical research findings, thus leading to poorly conceptualized and therefore potentially harmful policy and management decisions.  相似文献   
112.
旋风炉附烧处理后解毒铬渣的安定性研究   总被引:1,自引:0,他引:1  
着重阐明了铬渣经肇风炉附烧及炉餐水淬处理后生成的玻璃体粒化解毒渣的安定性问题,通过对解毒渣的物相结构,浸溶性和高温稳定性等试验分析,最终判明解毒渣在≤500℃条件下没有玻璃化倾向,在自然环境中储放和用作建材,都是安定和安全的。  相似文献   
113.
马伯文 《上海环境科学》2000,19(11):539-540
1 德国热电联产联供概况 德国的电力市场构成比较复杂,从国家到地方大约有1000家电力公司在运行。其中9家跨地区的大公司控制着全国大约85%的发电量和大部分跨地区的电力输送,有些小的电力公司和地方电力公司从这些大公司购买电力。在发展热电联产过程中存在着:电力价格持续走低,投资回收期偏长,电厂建设在环保方面的许可程序复杂等发展障碍。但德国政府从减少温室气体排放和减少核电量的环保角度出发,鼓励发展热电联产;再加上天然气价格比较便宜,以及欧盟倡导能源市场解放运动对德国的影响,德国在欧盟中热电联产发展处于中上水平,其热电联产的发电量占全国总发电量的14%,总装机容量超过22000MW。  相似文献   
114.
Ant foraging behavior: ambient temperature influences prey selection   总被引:2,自引:0,他引:2  
Summary When prey of two sizes (6 and 32 mg) were offered in a choice situation to foragers of the ant Formica schaufussi at different ambient temperatures, significantly more workers rejected the smaller prey at low temperatures, whereas at high temperatures workers accepted the less profitable smaller item. Foragers scavenge for arthropod prey over a temperature range of 15–40°C, and increasing temperature significantly increases a forager's oxygen consumption, an index of energy expenditure.  相似文献   
115.
20世纪末,在美国马萨诸塞州的科德角,由于全球变暖的加剧,鸟类越冬出现了向北迁移的现象,这种北移与全球气温异常和当地冬季最低气温上升是分不开的.这一现象以及最近的其它研究结果都表明:最近的20年期间,全球变暖已造成规模大、范围广的生物地理意义上的变化,并对地球生态系统和人类构成了潜在的威胁.由于城市扩展引起的地方生境的变化主要对栖息地偏北的森林鸟类产生影响.在科德角,当地居民居住地扩大对鸟类栖息地分布的影响,在21世纪初,尚不及温室效应的影响大,但是,如果城市继续扩大,也许其影响会不亚干全球变暖.  相似文献   
116.
Insular Endemic Plants Lack Defenses Against Herbivores   总被引:3,自引:0,他引:3  
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117.
A model is presented for predicting boll weevil, Anthonomus grandis Boheman, feeding damage to cotton. The model uses appropriate probability theory based on behavioral components of male and nonreproducing female boll weevils and includes the effects of (1) differential feeding site preferences, (2) previous damage to the sites, and (3) individual insect behavior extended to feeding damage caused by a population of insects. The model is sensitive to both crop and insect parameters. An example of how this model can be used in an insect-crop ecosystem simulation is offered.  相似文献   
118.
Standard samples, that is matrices containing precisely known concentrations of various radionuclides, are necessary adjuncts to any analytical quality control program. In general, we prefer the use of “natural matrix standards,” samples into which the radionuclides have become incorporated under natural conditions, and over as long a time span as possible. Under some circumstances, however, real advantages are offered by “spiked sample standards” samples to which the isotope of interest has been added in a precisely known amount, at the time of preparing the standard. It is our purpose to discuss the advantages and disadvantages of spiked standards and to contrast them with those of natural matrix standards, as well as to discuss the preparation of the former class of standards and the evidence supporting our recommendation of caution in their use.In general, spiked standards offer advantages of low cost of preparation, of advance assurance that the amount and chemical form of the radioisotopes added are known, and of the possibility of preparation of unnatural matrices, or of nuclides that are to be expected but not yet to be found in nature. The most salient disadvantages of spiked standards derive from the usual uncertainty concerning the concentration of any radionuclides in the matrix before spiking and from the difficulty of insuring that there will be no difference in analytical behavior between the spike and the same isotope that has become incorporated in the matrix under natural conditions. Consideration of these advantages and disadvantages leads to identification of a list of special problems for which spiked standards may be advantageous and of a list of precautions indicated in the interpretation of the resulting data. The argument against the general applicability of spiked standards appear overwhelming.  相似文献   
119.
Gao  Xueping  Song  Qinglin  Sun  Bowen  Song  Huifang 《Environmental Fluid Mechanics》2019,19(4):1005-1024

Selective withdrawal is commonly implemented in nonlinearly stratified ambient, which typically has stratified ambient conditions, for purposes of controlling quality. A floating intake is applied as an effective facility of selective withdrawal. However, the outflow dynamics of a floating intake in a nonlinearly stratified ambient have been disregarded, which has a significant effect on the outflow water quality of a reservoir. Experiments were conducted to investigate the effect of thermal stratification on the flow characteristics using particle image velocimetry at three temperature distributions (no stratification, weak stratification and strong stratification). The flow fields upstream of the floating intake showed that the withdrawal layer was formed inhibited by the thermal stratification. And strong stratification produced the thinner withdrawal layer thickness, leading to a larger nonuniform coefficient of the velocity profile. To quantitatively describe the velocity profiles, formulas of dimensionless velocity profiles were proposed. The flow developments were analysed, and the virtual control points located 0.56d above the floating intake (where d is the straight pipe diameter of the floating intake) were obtained. The positions of virtual control points mainly depended on the withdrawal discharge. The decay rate of the velocity along the horizontal line passing through the virtual control point was inversely proportional to the stratification intensity.

  相似文献   
120.
MacNally R  Bowen M  Howes A  McAlpine CA  Maron M 《Ecology》2012,93(3):668-678
Some species have disproportionate influence on assemblage structure, given their numbers or biomass. Most examples of such "strong interactors" come from small-scale experiments or from observations of the effects of invasive species. There is evidence that entire avian assemblages in open woodlands can be influenced strongly by individual species over very large areas in eastern Australia, with small-bodied species (< 50 g) being adversely affected. We used data from repeated surveys in 371 sites in seven districts across a region from Victoria to Queensland (> 2000 km). A series of linked Bayesian models was used to identify large-bodied (> or = 50 g) bird species that were associated with changes in occurrence and abundance of small-bodied species. One native species, the Noisy Miner (Manorina melanocephala; family Meliphagidae), was objectively identified as the sole large-bodied species having similar detrimental effects in all districts, depressing occurrence of 57 of 71 small-bodied species. Adverse effects on abundances of small-bodied species were profound when the Noisy Miner occurred with mean site abundances > or = 1.6 birds/2 ha. The Noisy Miner may be the first species to have been shown to influence whole-of-avifauna assemblage structure through despotic aggressiveness over subcontinental scales. These substantial shifts in occurrence rates and abundances of small-bodied species flow on to alter species abundance distributions of entire assemblages over much of eastern Australia.  相似文献   
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