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361.
For species listed under the U.S. Endangered Species Act (ESA), the U.S. Fish and Wildlife Service and National Marine Fisheries Service are tasked with writing recovery plans that include “objective, measurable criteria” that define when a species is no longer at risk of extinction, but neither the act itself nor agency guidelines provide an explicit definition of objective, measurable criteria. Past reviews of recovery plans, including one published in 2012, show that many criteria lack quantitative metrics with clear biological rationale and are not meeting the measureable and objective mandate. I reviewed how objective, measureable criteria have been defined implicitly and explicitly in peer‐reviewed literature, the ESA, other U.S. statutes, and legal decisions. Based on a synthesis of these sources, I propose the following 6 standards be used as minimum requirements for objective, measurable criteria: contain a quantitative threshold with calculable units, stipulate a timeframe over which they must be met, explicitly define the spatial extent or population to which they apply, specify a sampling procedure that includes sample size, specify a statistical significance level, and include justification by providing scientific evidence that the criteria define a species whose extinction risk has been reduced to the desired level. To meet these 6 standards, I suggest that recovery plans be explicitly guided by and organized around a population viability modeling framework even if data or agency resources are too limited to complete a viability model. When data and resources are available, recovery criteria can be developed from the population viability model results, but when data and resources are insufficient for model implementation, extinction risk thresholds can be used as criteria. A recovery‐planning approach centered on viability modeling will also yield appropriately focused data‐acquisition and monitoring plans and will facilitate a seamless transition from recovery planning to delisting. Un Marco de Referencia para Desarrollar Criterios de Recuperación Objetivos y Medibles para Especies Amenazadas y en Peligro  相似文献   
362.
Abstract: Illegal use of natural resources is a threat to biodiversity globally, but research on illegal activities has methodological challenges. We examined 100 studies that empirically identify targeted resources, techniques used to procure resources illegally, locations of illegal activities, characteristics of typical violators, incentives driving illegal use of resources, magnitude of the problem of illegal use (e.g., quantities used), or frequency of illegal activity. We based our evaluation of the methods used in these studies on their ability to provide these empirical data, relative labor demands, training and technology requirements, and levels of uncontrollable bias. We evaluated eight different methods: law‐enforcement records, indirect observation, self‐reporting, direct observation, direct questioning, randomized response technique (a survey method designed to improve accuracy of responses to sensitive questions), forensics, and modeling. Different situations favored different methods, each with distinct advantages and limitations. Six context‐specific factors—location of resource use (in situ vs. ex situ), budget, technology and training capacity, ease of detection of illegal activity, scope of illegal activity (limited vs. widespread), and researchers’ willingness to accept bias in results—help narrow the choice of methods. Several methodological concerns applied to any study of illegal resource use: regular monitoring can detect trends; modeling can incorporate sampling error and data uncertainties; researchers must manage levels of bias that vary between methods; triangulation of results from multiple methods can improve accuracy. No method is a panacea, but a combination of techniques can help address the lack of data on illegal activity. Researchers empirically compared results from different methods in only four studies, and no one has compared more than two methods simultaneously. Conservation would benefit from more research focused on: methods comparisons that include cost effectiveness, time efficiency, and statistical rigor; unique applications of the eight techniques currently in use; and testing of new methods.  相似文献   
363.
Abstract:  The national systems used in the evaluation of extinction risk are often touted as more readily applied and somehow more regionally appropriate than the system of the International Union for Conservation of Nature (IUCN). We compared risk assessments of the Mexican national system (method for evaluation of risk of extinction of wild species [MER]) with the IUCN system for the 16 Polianthes taxa (Agavaceae), a genus of plants with marked variation in distribution sizes. We used a novel combination of herbarium data, geographic information systems (GIS), and species distribution models to provide rapid, repeatable estimates of extinction risk. Our GIS method showed that the MER and the IUCN system use similar data. Our comparison illustrates how the IUCN method can be applied even when all desirable data are not available, and that the MER offers no special regional advantage with respect to the IUCN regional system. Instead, our results coincided, with both systems identifying 14 taxa of conservation concern and the remaining two taxa of low risk, largely because both systems use similar information. An obstacle for the application of the MER is that there are no standards for quantifying the criteria of habitat condition and intrinsic biological vulnerability. If these impossible-to-quantify criteria are left out, what are left are geographical distribution and the impact of human activity, essentially the considerations we were able to assess for the IUCN method. Our method has the advantage of making the IUCN criteria easy to apply, and because each step can be standardized between studies, it ensures greater comparability of extinction risk estimates among taxa.  相似文献   
364.
Major Conservation Policy Issues for Biodiversity in Oceania   总被引:2,自引:0,他引:2  
Abstract:  Oceania is a diverse region encompassing Australia, Melanesia, Micronesia, New Zealand, and Polynesia, and it contains six of the world's 39 hotspots of diversity. It has a poor record for extinctions, particularly for birds on islands and mammals. Major causes include habitat loss and degradation, invasive species, and overexploitation. We identified six major threatening processes (habitat loss and degradation, invasive species, climate change, overexploitation, pollution, and disease) based on a comprehensive review of the literature and for each developed a set of conservation policies. Many policies reflect the urgent need to deal with the effects of burgeoning human populations (expected to increase significantly in the region) on biodiversity. There is considerable difference in resources for conservation, including people and available scientific information, which are heavily biased toward more developed countries in Oceania. Most scientific publications analyzed for four threats (habitat loss, invasive species, overexploitation, and pollution) are from developed countries: 88.6% of Web of Science publications were from Australia (53.7%), New Zealand (24.3%), and Hawaiian Islands (10.5%). Many island states have limited resources or expertise. Even countries that do (e.g., Australia, New Zealand) have ongoing and emerging significant challenges, particularly with the interactive effects of climate change. Oceania will require the implementation of effective policies for conservation if the region's poor record on extinctions is not to continue .  相似文献   
365.
Many marine invertebrate species facing potential extinction have uncertain taxonomies and poorly known demographic and ecological traits. Uncertainties are compounded when potential extinction drivers are climate and ocean changes whose effects on even widespread and abundant species are only partially understood. The U.S. Endangered Species Act mandates conservation management decisions founded on the extinction risk to species based on the best available science at the time of consideration—requiring prompt action rather than awaiting better information. We developed an expert‐opinion threat‐based approach that entails a structured voting system to assess extinction risk from climate and ocean changes and other threats to 82 coral species for which population status and threat response information was limited. Such methods are urgently needed because constrained budgets and manpower will continue to hinder the availability of desired data for many potentially vulnerable marine species. Significant species‐specific information gaps and uncertainties precluded quantitative assessments of habitat loss or population declines and necessitated increased reliance on demographic characteristics and threat vulnerabilities at genus or family levels. Adapting some methods (e.g., a structured voting system) used during other assessments and developing some new approaches (e.g., integrated assessment of threats and demographic characteristics), we rated the importance of threats contributing to coral extinction risk and assessed those threats against population status and trend information to evaluate each species’ extinction risk over the 21st century. This qualitative assessment resulted in a ranking with an uncertainty range for each species according to their estimated likelihood of extinction. We offer guidance on approaches for future biological extinction risk assessments, especially in cases of data‐limited species likely to be affected by global‐scale threats. Incorporación del Cambio Climático y Oceánico en Estudios de Riesgo de Extinción para 82 Especies de Coral  相似文献   
366.
To better understand the potential causes of visibility impairment in autumn and winter in Chengdu, relative humidity(RH), visibility, the concentrations of PM_(2.5) and its chemical components were on-line measured continuously in Chengdu from Nov. 2016 to Jan. 2017.Six obvious haze episodes occurred in Chengdu, with the total time of haze episodes accounted for more than 90% of the total observation period, and higher NO_2 concentrations and RH were related to the high particle concentrations in haze episodes. The visibility decreased in a non-linear tendency under different RH conditions with the increase of PM_(2.5) concentrations, which was more sensitive to RH under lower PM_(2.5) concentrations. The threshold concentration of PM_(2.5) got more smaller with the increase of RH. During the entire observation period, organic matter(OM) was the largest contributor(31.12% to extinction coefficient(bext)), followed by NH_4NO_3 and(NH_4)_2SO_4 with 28.03% and 23.01%, respectively.However, with the visibility impairment from Type I(visibility 10 km) to Type IV(visibility ≤ 2 km), the contribution of OM to bextdecreased from 38.12% to 26.77%, while the contribution of NH_4NO_3 and(NH_4)_2SO_4 to bextincreased from 19.09% and 20.20% to 34.29% and 24.35%, respectively, and NH_4NO_3 became the largest contributor to bextat Type IV. The results showed that OM and NH_4NO_3 were the key components of PM_(2.5) for visibility impairment in Chengdu, indicating that the control of precursors emissions of carbonaceous species and NH_4NO_3 could effectively improve the visibility in Chengdu.  相似文献   
367.
大气气溶胶消光系数的计算方法研究   总被引:3,自引:0,他引:3  
基于Mie散射理论,在过去的同种颗粒消光系数计算的基础上,对多种成分颗粒的大气气溶胶,建立了消光系数的平均(理论的)计算方法,同时,利用容积占比等效折射率,建立了消光系数的等效计算方法,验证了该等效法的可靠性。随着最近实验测量技术的发展,可将大气气溶胶分成成分相近的若干组分,应用上述方法可按这些组分去计算成分复杂的实际的大气气溶胶的消光系数。对Kleiner Feldberg测量数据的应用得到了较理想的结果,这充分说明了方法的可靠性和可行性。该方法的建立,不仅为气溶胶的光学特性研究提供了一个新的理论方法,也为分析大气环境质量提供了有力的支持。  相似文献   
368.
The abundance and photosynthetic activity ofpicocyanobacteria in the oligotrophic alpine lake Traunseewere measured at a station located close to the outlet ofindustrial soda waste and at a mid-lake reference stationduring spring, 1999 through to autumn, 2000.Picocyanobacterial numbers measured by flow cytometry inTraunsee (0.7–13.2 × 104 ml-1) were comparable tothose of other oligotrophic lakes, and there was nosignificant difference between the contaminated and thereference sampling location. Picoplankton (<2 m)photosynthetic rates measured in vitro by the 14C-technique were significantly reduced at the contaminated siterelative to the reference station at low photosyntheticallyavailable radiation (10 E m-2 s-1), while nodifference between these two stations was found at moderatelyhigh light intensity (100 E m-2 s-1). Theinvestigation was complemented by laboratory experiments withcultured picocyanobacteria. Three Synechococcus spp.strains were exposed to water taken from either of the twoTraunsee stations and from a control station located inneighbouring Attersee. Cell-specific photosynthetic activitymeasured by 4-h in vitro incubations revealed no significantdifference among the three stations investigated. Growthrates of the same three Synechococcus spp. strains weremeasured by flow cytometry over several days in thelaboratory. One strain, in particular, was sensitive to watertaken from the contaminated site; growth rate of this strainwas significantly reduced, relative to when exposed to watertaken from the reference station. Taken together, our resultsdemonstrate that picocyanobacteria are highly sensitivebioindicators of contaminant stress. The overall impact ofthe emissions from the industrial outlet on thepicocyanobacteria was, however, relatively minor.  相似文献   
369.
370.
PROBLEM: Prior research has demonstrated that suspended/revoked drivers pose a significant traffic risk, but until now little has been known about whether, and if so how, this risk varies as a function of the reason for suspension/revocation. METHOD: This study classifies suspended/revoked drivers into subgroups based on their reason for suspension/revocation, and then develops demographic and driving record profiles for each group. Separate driving record profiles are developed for the following traffic safety indicators, measured 3 years prior to the suspension/revocation action: (a) total crashes, (b) fatal/injury crashes, (c) total traffic convictions, and (d) total incidents (crashes + convictions). RESULTS: The findings clearly show that: (a) suspended/revoked drivers are a heterogeneous group, both demographically and in their driving behavior; (b) some suspended drivers, such as those suspended/revoked for a non-driving offense, have low traffic risks that are not much higher than those of validly-licensed drivers, and; (c) all suspended groups have elevated crash and conviction rates, compared to validly-licensed drivers. DISCUSSION: The implications of these findings for current laws and policies targeting suspended/revoked drivers are discussed, and recommendations for improving these laws/policies are presented. IMPACT ON INDUSTRY: None.  相似文献   
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