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361.
Consuming nations and industry segments within them play a crucial role in the success of commodity agreements. For individual firms the desirability of the agreements is seen to depend on the form of the agency agreement and the competitive position of the firm in both the domestic and world market. Both the benefits and costs to producing and consuming nations are analysed. The mechanism of the agreements is analysed as well as the problems that lead to their limitation or termination.  相似文献   
362.
Abstract: Ecological theory predicts that species with restricted geographic ranges will have the highest probability of extinction, but species with extensive distributions and high population densities can also exhibit widespread population losses. In the western United States populations of northern leopard frogs (Lithobates pipiens)—historically one of the most widespread frogs in North America—have declined dramatically in abundance and geographic distribution. To assess the status of leopard frogs in Colorado and evaluate causes of decline, we coupled statewide surveys of 196 historically occupied sites with intensive sampling of 274 wetlands stratified by land use. We used an information‐theoretic approach to evaluate the contributions of factors at multiple spatial extents in explaining the contemporary distribution of leopard frogs. Our results indicate leopard frogs have declined in Colorado, but this decline was regionally variable. The lowest proportion of occupied wetlands occurred in eastern Colorado (2–28%), coincident with urban development and colonization by non‐native bullfrogs (Lithobates catesbeianus). Variables at several spatial extents explained observed leopard frog distributional patterns. In low‐elevation wetlands introduced fishes, bullfrogs, and urbanization or suburbanization associated negatively with leopard frog occurrence, whereas wetland area was positively associated with occurrence. Leopard frogs were more abundant and widespread west of the Continental Divide, where urban development and bullfrog abundance were low. Although the pathogenic chytrid Batrachochytrium dendrobatidis (Bd) was not selected in our best‐supported models, the nearly complete extirpation of leopard frogs from montane wetlands could reflect the individual or interactive effects of Bd and climate patterns. Our results highlight the importance of considering multiple, competing hypotheses to explain species declines, particularly when implicated factors operate at different spatial extents.  相似文献   
363.
以中国环境管理干部学院为例,国际服务外包课程是在国际服务贸易和服务外包产业迅速发展的背景下设置的。通过对我国服务外包行业发展现状和人才需求特点的分析,对国际服务外包课程设置提出系统性、开放性、职业性、实践性的构想,以及调整专业结构、建立灵活人才培养模式、加强学生实习实训、利用现有资源和政策支持以及做好服务外包人才就业工作的相关措施,以确保高职院校国际服务外包课程设计的科学性与可行性。  相似文献   
364.
We study the effectiveness of emission targets under the Kyoto Protocol with respect to reducing CO2 emissions. Using country-level and US state-level panel data and employing the synthetic control method, we find very little evidence for an emission reduction effect for the major emitters among the Annex B countries with binding emission targets. More generally, we also show that evaluating the effectiveness of international environmental policies at the country level comes with a number of empirical challenges that may invalidate findings based on more traditional panel data approaches.  相似文献   
365.
早期的企业国际竞争力研究主要是围绕企业的市场份额、盈利能力等经济效益及其影响因素展开.随着国际范围内针对煤炭企业环保业绩考评的持续升温,煤炭企业国际竞争力的分析模型也需要进行重新修正.在这一背景下,基于波特的钻石模型提出了基于环境因素的煤炭企业国际竞争力分析模型,并以河南煤炭企业为例进行了分析研究,以期能为煤炭企业的环境战略管理决策提供参考.  相似文献   
366.
采用16S rRNA方法对江苏省新沂河的底泥样品进行了厌氧氨氧化菌的原位检测,建立了样品的16S rRNA克隆文库,共包括6个16S rRNA克隆序列.对文库中克隆序列利用ARB软件包进行了排队分析及系统发育树的绘制.分析结果表明,新沂河底泥样品中含有与已知厌氧氨氧化菌Candidatus“Brocadia anammoxidans”相似性为91%的16S rRNA基因,经鉴定为厌氧氨氧化菌Brocadia分支的新种类.样品中还含有组成Planctomycetes新分支的16S rRNA基因,它们与已知厌氧氨氧化菌序列的遗传距离较远,其微生物特性还有待进一步研究.厌氧氨氧化菌在淡水环境中的发现将有助于进一步研究厌氧氨氧化过程在受损淡水生态系统修复重建中的作用,重新认识其中的氮循环过程.  相似文献   
367.
信息工作在当代社会各个领域中都占有很重要的位置。有效而充分地发挥国际职业安全卫生信息中心(CIS)中国国家中心的作用,加强国内外在职业安全卫生方面的合作与交流,实现信息资源共享,对进一步做好我国职业安全卫生工作必将产生巨大的促进作用。简要介绍了CIS和CIS中国国家中心的成立和发展情况及其主要工作,着重从它们的发展轨迹中探讨如何充分发挥CIS中国国家中心的作用,进一步做好我国职业安全卫生工作。  相似文献   
368.
To understand acute toxicity and oxidative stress of perfluorinated compounds in the freshwater ecosystems, we exposed freshwater mussels (Unio ravoisieri) to perfluorooctane sulfonate (PFOS), over a range of concentrations from 10 to 100?mg/L, in a laboratory experiment. Lethal concentration (LC50) was of about 65.9?mg/L after 96?h of exposure. The oxidative stress was assessed in gill and digestive gland of the freshwater mussels after 7 days of exposure to different nominal PFOS concentrations (C1=?2?mg/L, C2?=?6?mg/L and C3=?10?mg/L). C1 and C2 increased significantly (p?<?.05) the superoxide dismutase activity in both tissues compared, while the highest C3 decreased the enzyme activity. This implements an unfavourable response that highlights the excess of reactive oxygen species produced after contamination. The Catalase activity was also increased by about 40.05% and 66.63%, respectively, in gill and digestive gland after exposure to C3. The Malondialdehyde (MDA) level was increased in both gill and digestive gland in a concentration-dependent pattern. In contrast, the contamination of U. ravoisieri by PFOS did not affect the acetylcholinesterase activity in both organs (p?>?.005). These results provided information on potential biomarkers that could be effectively applied for the monitoring of freshwater ecosystem using indicator species such as U. ravoisieri.  相似文献   
369.
选取中国东南沿海闽江河口潮汐淡水沼泽湿地土壤作为研究对象,研究不同盐分(淡水对照、低盐处理、高盐处理)和不同淹水(CK、CK+15 cm、CK+30 cm)交互处理对土壤磷形态和磷酸酶活性的影响.结果表明,在闽江河口潮汐淡水沼泽湿地土壤中,无机磷是土壤总磷的主要赋存形态,约占总磷含量的68%~82%,有机磷含量约占总磷的18%~32%.无机磷以铁铝结合态磷为主(60%~66%),其次为钙结合态磷和闭蓄态磷.淹水处理对磷的总量和形态的影响有限,盐分变化对磷的总量和形态影响显著.低盐处理可增加铁铝结合态磷、闭蓄态磷含量及碱性磷酸酶活性,而高盐处理则对它们表现出抑制作用.随着盐分的增加,土壤总磷含量逐渐降低,土壤中钙结合态磷含量和磷酸盐含量将逐渐升高.相关分析表明,有机磷含量与土壤碱性磷酸酶活性呈负相关,无机磷含量与土壤碱性磷酸酶活性呈正相关.当盐分由淡水变化至低盐时,土壤磷的形态主要由有机磷向无机磷转化;而当盐分由低盐变化至高盐时,无机磷占比降低,有机磷占比增加.研究结果表明,碱性磷酸酶活性在磷形态对盐分和淹水的响应中发挥着重要作用.  相似文献   
370.
International relations and disaster studies have much to gain by thinking critically about their respective theoretical and epistemological assumptions. Yet, few studies to date have sought to assess the potential value of linking these two disciplines. This paper begins to address this shortfall by examining the relationship between disasters and conflict as a research sphere that intersects international relations and disaster studies. Through an analysis of whether or not disasters contribute to intra‐national and international conflict, this paper not only provides a review of the state of the art, but also serves to invite scholars to reflect on related concepts from other fields to strengthen their own approaches to the study of disasters in an international setting. An evaluation of the conceptual and theoretical contributions of each subject area provides useful heuristics for the development of disaster–conflict scholarship and encourages alternative modes of knowledge production through interdisciplinarity.  相似文献   
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