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891.
892.
893.
The bean weevils Callosobruchus maculatus (F.) and C. rhodesianus (Pic.) both laid fewer eggs on previously infested adzuki beans than on fresh beans, even after eggs were removed. A variety of experimental treatments demonstrated the existence of an oviposition marker with ether soluble components. Callosobruchus rhodesianus was inhibited from ovipositing by the C. maculatus marker, but not vice versa. 相似文献
894.
Summary The responses of individually marked pikas (Ochotona princeps) to terrestrial predators were investigated in 1980 and 1981 in the Rocky Mountains of Colorado. Pikas uttered short call vocalizations in a variety of contexts: preceding or following an individual's movement, and in response to conspecifics, other nonpredaceous mammals and predators. Adult pikas apparently discriminated contexts in which predators were present by short calling more frequently and for longer duration compared with calling in nonpredator contexts. Short calls uttered by juveniles were similar in all contexts.Adults responded differently to two types of terrestrial predators: weasels and pine martens. Pikas called less frequently in response to weasels than to martens and avoided weasels more often than martens. They delayed the initiation of calling following the first sighting of a weasel more often than to martens. Weasels were determined to be more effective predators of pikas than martens, and these asymmetries in behavior and alarm vocalizations may indicate that responses reduce an individual's risk of predaton by weasels.Both male and female pikas called in response to predators, and residents called more often than nonresidents. The possible function of predator-related vocalization in pikas is discussed. It is suggested that calls to predators may function to warn local residents, which in pikas are usually closely related. 相似文献
895.
Linda E. Smith 《Journal of Safety Research》1994,25(4):221-227
This study compared fire-related injuries from two ongoing data systems to determine how to combine them to provide improved estimates of U.S. residential fire-related injuries. National estimates and characteristics of patients treated in hospital emergency rooms for fire-related injuries were compared with injuries in a database of fires attended by the fire service. National estimates, age, and diagnosis distributions of injuries seen by both a hospital and the fire service were very similar in the two systems, indicating that the systems overlapped for this segment of injuries. Each system also contained a segment of fire-related injuries that was not included in the other. Combining the overlapping segment of injuries with segments that did not overlap resulted in an estimate of 45,000–47,000 U.S. fire-related injuries, the most com-prehensive estimate of U.S. residential fire-related injuries available to date. 相似文献
896.
Ju-Chang Huang Russell L. Smith 《Journal of the American Water Resources Association》1974,10(5):942-951
ABSTRACT: Up to date there are still not many instances that can be found on the practice of a totally closed system of water supply, treatment, and reuse. In the United States, this is partly because the Public Health Service has discouraged such a practice. However, are there sound scientific reasons to support such a decision or is it purely a matter of psychological reason? Are the treatment technologies available today able to achieve the integrated closed system at a reasonable cost, yet without risking the public health? Are there some extra precautions that must be taken in practicing the direct reuse for the drinking purpose? These questions are discussed in this article. Current available technologies for advanced waste treatment are briefly reviewed and the treated effluent qualities obtained by the authors and others are used as a focal point of discussion on the feasibility of practicing the closed system. For this purpose, the treated effluent qualities are compared to the “Ranges of Promulgated Standards for Raw Water Sources of Domestic Water Supply” which have been used by the Public Health Service and several state regulatory agencies. 相似文献
897.
898.
Feeding frequency and parental division of labour in the double-brooded great tit Parus major 总被引:2,自引:0,他引:2
Henrik G. Smith Hans Källander Kristina Fontell Martin Ljungström 《Behavioral ecology and sociobiology》1988,22(6):447-453
Summary We studied the relative contribution of each sex and total effort expended in feeding nestlings in the great tit Parus major in relation to artificially altered brood size. A recent model suggests that feeding frequency should reflect the optimal trade-off between parental and fledgling survival, the former being negatively, the latter positively, influenced by high feeding frequencies. In both sexes weight loss was linearly related to feeding frequency. Since fledgling survival increases with nestling weight, the conditions of this model are fulfilled. However, in contrast to the predictions of the model, the total feeding frequency for both sexes combined did not differ between control and enlarged broods, but was lower for reduced ones. This outcome was not the result of a physiologically related inability of the parents to increase their delivery rate. Instead, we suggest that parents with enlarged broods could not find sufficient amounts of prey large enough to be economically worth transporting to the nest. Differences in brood-provisioning rates between the sexes may arise because costs and benefits of feeding nestlings may differ. Females lost more weight than males during the nesting period, but maintained a relatively higher weight during the incubation period. The relationship between weight loss and feeding frequency was similar for both sexes. Male and female brood-feeding frequency was related to brood size in a similar way. This is discussed in light of the great tit's mating system and the fact that the great tit is facultatively double-brooded. 相似文献
899.
The Ok Tedi copper mine discharges overburden and ore residues into the Ok Tedi, a tributary of the Fly River. These discharges result in elevated suspended solids and dissolved and particulate associated copper. Analyses of covariance were performed to establish statistical model of the relationships between the mine discharges and fish catches between 1983 and 1988. These models were then extrapolated to predict the affects of future mine discharges on fish catches. The models predicted that if the observed effects were caused by particulate associated copper, the period of greatest impact will be between 1989 and 1993, following which catches should be close to 1988 levels for the remainder of mine life. Some additional catches not included in the data set used to derive the models were found to fit the model predictions well. As the predicted period of greatest impact is short and most species reproduce away from the river channel, the ability of the fish communities to undergo partial recovery after 1991 should be maintained. 相似文献
900.
Composting technologies and control systems have reached an advanced stage of development, but these are too complex and expensive for most agricultural practitioners for treating livestock slurries. The development of simple, but robust and cost-effective techniques for composting animal slurries is therefore required to realise the potential benefits of waste sanitation and soil improvement associated with composted livestock manures. Cattle slurry solid fraction (SF) was collected at the rates of 4m(3)h(-1) and 1m(3)h(-1) and composted in tall (1.7 m) and short (1.2m) static piles, to evaluate the physicochemical characteristics and nutrient dynamics of SF during composting without addition of bulking agent materials, and without turning or water addition. Highest maximum temperatures (62-64 °C) were measured in tall piles compared to short piles (52 °C). However, maximum rates of organic matter (OM) destruction were observed at mesophilic temperature ranges in short piles, compared to tall piles, whereas thermophilic temperatures in tall piles maximised sanitation and enhanced moisture reduction. Final OM losses were within the range of 520-660 g kg(-1) dry solids and the net loss of OM significantly (P<0.001) increased nutrient concentrations during the composting period. An advanced degree of stabilization of the SF was indicated by low final pile temperatures and C/N ratio, low concentrations of NH(4)(+) and increased concentrations of NO(3)(-) in SF composts. The results indicated that minimum intervention composting of SF in static piles over 168 days can produce agronomically effective organic soil amendments containing significant amounts of OM (772-856 g kg(-1)) and plant nutrients. The implications of a minimal intervention management approach to composting SF on compost pathogen reduction are discussed and possible measures to improve sanitation are suggested. 相似文献