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81.
Summary We examined the hypothesis that among free-ranging rhesus monkeys (Macaca mulatta), maternal care patterns during estrus influence chances of conception independently of variation in the timing of the postpartum resumption of mating. We observed 24 multiparous mothers and their infants before and during the 1990 mating season. When mothers resumed mating, they abruptly sought less contact with their infants. Infants responded by increasing the rates with which they emitted distress calls and attempted to make nipple contact. High levels of maternal rejection and low levels of maternal nipple contact initiation during the mother's first estrus were associated with low suckling frequencies and high chances of conception. Although demanding infants had some success in gaining access to the nipples of reluctant mothers during estrus, mothers' chances of conception were unrelated to measures of infant demand or distress calling. Individual differences in maternal behavior regulating access to the nipple during estrus were unrelated to those shown previously. During estrus, mothers appeared to regulate nipple contact according to their infant's age and perhaps other factors related to its vulnerability. Correspondence to: C.M. Berman  相似文献   
82.
ABSTRACT: Evaporative heat loss is an essential component of any heat budget used for the modeling of lake water temperatures. Seven evaporative heat loss equations were tested in a year-round, physically-based temperature and dissolved oxygen model for lakes. Deciding which equation to choose for use in the year-round model was based on the goodness of fit of the simulated vs. measured surface temperatures, which were taken at a depth of 1 m below the water surface. An equation which includes free and forced convection components and which was previously used for cooling ponds gave the best fit between temperature simulations and measurements.  相似文献   
83.
Concentrations of CH4 and N2O have been determined in bubbles extracted from the Mt. Logan (Yukon) and 20D (south Greenland) ice cores. The enclosure dates of the trapped gas samples range from 1802 to 1960; thus these data help to document the anthropogenic increases of these two greenhouse gases in the Northen Hemisphere atmosphere. In general, the new data are in accord with previous ice core studies showing accelerating increases in concentration of both gases since 1900. The Mt. Logan records appear to be the first for any trace gases from alpine glacial ice. The present data set is too sparse to be conclusive, but suggests generally higher CH4 concentrations over south Greenland than Mt. Logan, particularly for the 1850 - 1900 period.  相似文献   
84.
A nested multiplex polymerase chain reaction (PCR) assay has been developed that allows the discrimination between six bivalve larvae common to Danish coastal waters (Cerastoderma edule, Macoma balthica, Mytilus edulis, Spisula subtruncata, Ensis americanus and members of the order Myoida). This assay involves the simultaneous use of a pair of general universally targeted 18S rRNA gene primers, five specific 18S rRNA gene targeted oligonucleotide primers internal (nested) to the universal primer pair and one species-specific primer that is not nested (Mya). The specificity of each primer was evaluated in silico, empirically, and verified further by sequencing of amplification products from single larvae collected from plankton samples. Identification of individually isolated bivalve larvae from plankton samples was based on the size of the PCR product produced by the specific primers after visualisation by agarose gel electrophoresis. Preliminary studies indicated that this method was suitable for use with freshly collected and preserved larvae, and is therefore suitable for field application.Communicated by M. Kühl, Helsingør  相似文献   
85.
Summary The energetic cost of guarding estrous females has been assumed to be a potentially major factor in limiting the duration of male consortships in a number of polygamous species. This issue has been examined in the present study by assessing changes in the usual activity budgets of 13 male and 20 female yellow baboons which occurred during their consortships.The percent of time adult males spent feeding was strongly related to their agonistic rank: Higher-ranking males fed proportionately more than lower-ranking males while not in consort, and they showed a relatively greater decrease in feeding time during consortships.The proportion of time females spent feeding was related to their agonistic rank and (to a lesser degree) to their parity. Higher-ranking females fed more than lower-ranking females outside of consortships, and showed a relatively greater decrease in time spent feeding while in consort. Nulliparous females tended to feed more than parous females while not in consort; during consortships, the feeding time of nulliparous females decreased, while that of parous females increased slightly.The activity of male and female consort partners was most coordinated during the fertile cycle stage of the female partner, and least coordinated once the female had passed the fertile stage.Although reductions in feeding time during consortships were generally much more pronounced in males than in females, neither males nor females appeared to attain the undisturbed optimal feeding level for their sex while in consort.  相似文献   
86.
The percentage of the cross-sectional area of two objects (e.g., vehicles, hikers, or animals) that can be seen from each of their locations in a forested area is generally not the same. There is a directionality to the visibility between them. This is due to the relative positions and sizes of the vegetation and other view-blocking features between the objects. An analytical technique has been developed to help understand bidirectional visibility. Its use entails the construction of a visibility diagram containing the basic visibility information between observers in a given setting. An example is presented showing the use of the visibility diagram to determine visibility between two moving observers in a forested environment. The diagram is also used to determine the differences in the percentage each observer has of the other's visible cross-sectional area (bidirectional visibility). A discussion of the application of the technique in the planning or development of new facilities, as well as in forest and wildlife management, is provided.  相似文献   
87.
We investigated the variation in concentrations and profiles of various classes of organohalogenated compounds (OHCs) in different feather types, muscle tissue and preen oil from 15 white-tailed eagle (Haliaeetus albicilla) carcasses from Greenland. The influence of moult patterns and potential external contamination onto the feather surface was examined, while the present study is also the first to investigate the use of body feathers for OHC monitoring. Concentrations of sum polychlorinated biphenyls (PCBs) in feathers from white tailed eagles ranged from 2.3 ng/g in a primary wing feather to 4200 ng/g in body feathers. Using 300 mg of body feathers, almost 50 different OHCs could be quantified and median concentrations in body feathers were 10 fold higher than concentrations in tail feathers (rectrices) or primary wing feathers. Body feathers could be very useful for biomonitoring taking into account their easy sampling, short preparation time and high levels of OHCs. In addition, the effects of confounding variables such as feather size, moult and age are also minimised using body feathers. Correlations with concentrations in muscle tissue and preen oil were high and significant for all feather types (r ranging from 0.81 to 0.87 for sum PCBs). Significant differences in concentrations and profiles of OHCs were found between different primary feathers, indicating that the accumulation of OHCs in feathers varies over the moulting period (maximum three years). Washing of feathers with an organic solvent (acetone) resulted in a significant decrease in the measured concentrations of OHCs in feathers. However, our results indicated that preen oil is probably not the only contributor to the external contamination that can be removed by washing with acetone. Possibly dust and other particles may be of importance and may be sticking to the preened feathers. Rectrices washed only with water showed high and significant correlations with concentrations in muscle and preen oil as well. Washing with acetone therefore does not seem to be of great influence when relating to internal tissue concentrations. We recommend washing feathers only with distilled water in order to remove dirt and dust particles before analysis.  相似文献   
88.
89.
Rapidly growing cities along the Interstate-85 corridor from Atlanta, GA, to Raleigh, NC, rely on small rivers for water supply and waste assimilation. These rivers share commonalities including water supply stress during droughts, seasonally low flows for wastewater dilution, increasing drought and precipitation extremes, downstream eutrophication issues, and high regional aquatic diversity. Further challenges include rapid growth; sprawl that exacerbates water quality and infrastructure issues; water infrastructure that spans numerous counties and municipalities; and large numbers of septic systems. Holistic multi-jurisdiction cooperative water resource planning along with policy and infrastructure modifications is necessary to adapt to population growth and climate. We propose six actions to improve water infrastructure resilience: increase water-use efficiency by municipal, industrial, agricultural, and thermoelectric power sectors; adopt indirect potable reuse or closed loop systems; allow for water sharing during droughts but regulate inter-basin transfers to protect aquatic ecosystems; increase nutrient recovery and reduce discharges of carbon and nutrients in effluents; employ green infrastructure and better stormwater management to reduce nonpoint pollutant loadings and mitigate urban heat island effects; and apply the CRIDA framework to incorporate climate and hydrologic uncertainty into water planning.  相似文献   
90.
Objective: This study looks at mitigating and aggravating factors that are associated with the injury severity of pedestrians when they have crashes with another road user and overcomes existing limitations in the literature by focusing attention on the built environment and considering spatial correlation across crashes.

Method: Reports for 6,539 pedestrian crashes occurred in Denmark between 2006 and 2015 were merged with geographic information system resources containing detailed information about the built environment and exposure at the crash locations. A linearized spatial logit model estimated the probability of pedestrians sustaining a severe or fatal injury conditional on the occurrence of a crash with another road user.

Results: This study confirms previous findings about older pedestrians and intoxicated pedestrians being the most vulnerable road users and crashes with heavy vehicles and in roads with higher speed limits being related to the most severe outcomes. This study provides novel perspectives by showing positive spatial correlations of crashes with the same severity outcomes and emphasizing the role of the built environment in the proximity of the crash.

Conclusions: This study emphasizes the need for thinking about traffic calming measures, illumination solutions, road maintenance programs, and speed limit reductions. Moreover, this study emphasizes the role of the built environment, because shopping areas, residential areas, and walking traffic density are positively related to a reduction in pedestrian injury severity. Often, these areas have in common a larger pedestrian mass that is more likely to make other road users more aware and attentive, whereas the same does not seem to apply to areas with lower pedestrian density.  相似文献   

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