首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1311篇
  免费   120篇
  国内免费   387篇
安全科学   100篇
废物处理   42篇
环保管理   101篇
综合类   773篇
基础理论   207篇
污染及防治   222篇
评价与监测   307篇
社会与环境   42篇
灾害及防治   24篇
  2024年   14篇
  2023年   19篇
  2022年   55篇
  2021年   51篇
  2020年   60篇
  2019年   48篇
  2018年   57篇
  2017年   71篇
  2016年   81篇
  2015年   89篇
  2014年   96篇
  2013年   167篇
  2012年   116篇
  2011年   140篇
  2010年   89篇
  2009年   106篇
  2008年   67篇
  2007年   92篇
  2006年   63篇
  2005年   58篇
  2004年   29篇
  2003年   36篇
  2002年   28篇
  2001年   24篇
  2000年   27篇
  1999年   12篇
  1998年   26篇
  1997年   17篇
  1996年   15篇
  1995年   15篇
  1994年   8篇
  1993年   14篇
  1992年   3篇
  1991年   6篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   3篇
  1980年   1篇
  1978年   1篇
排序方式: 共有1818条查询结果,搜索用时 437 毫秒
401.
Rapid advancement in fetal diagnostic imaging has increased our ability to diagnose a multitude of anomalies in the prenatal period. The purpose of this chapter is to review our current understanding of prenatally diagnosed intra-abdominal lesions, and describe the current guidelines for the postnatal management and subsequent outcome for these lesions. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
402.
Global challenges have exacerbated a search for solutions to poverty and environmental degradation. Integration it was argued would help address the twin challenge. Integrated Water Resources Management (IWRM) was supposed to be that magic bullet and was embraced by scientists because of the clinical efficiency with which it argued for integrated analysis of sectors and resources and of systems and scale conditions. This paper argues that effective implementation of the Water-Energy-Food (WEF) Nexus can be supported by robust science. The corollary that robust science automatically leads to effective implementation is not always known to be true. The nexus approach sheds light on the challenges of implementation by introducing concepts of trade-offs and thresholds and consequently emphasizes the importance of transdisciplinary approaches to sustainable development. This paper reviews the results of recent research to offer tentative answers to the following questions: (a) Why is the governance dimension important to undertake an integrated analysis of water-energy-food challenges? (b) What does the nexus approach connote in normative and institutional terms? (c) What does implementation mean in nexus terms? (d) How can we establish if the nexus approach is an improvement over business as usual? and (e) What tools are available that would enable translation of results of scientific research to create an evidence base that would enable decision makers to act in support of sustainable development?  相似文献   
403.
404.
The thermal oxidative stability of ionic and emulsion ABS with various antioxidants and UV stabilizers was studied. It was found that Santonox R provides better protection than Irganox 1076 to both resins. It is also the case in formulations with Tinuvin 770 and Tinuvin 328.  相似文献   
405.
ABSTRACT: Mass balance models have been common tools in lake quality management for some years. However, verification for use on reservoirs, especially in the Western United States, has been seriously lacking, In this study, such a verification is attempted using data from the U.S EPA National Eutrophication Survey. Several models from the literature are compared for accuracy in application to the western reservoir data. Model standard error and correlation between estimated and observed reservoir phosphorus concentrations are the Criteria used for comparison. Standard errors am further used to calculate uncertainty of trophic state classification based on estimated phosphorus concentration. The model proposed by Dillon and Rigler (1974) proved most accurate, with a correlation coefficient of 0.86 and standard error of 0.2, based on logarithmic transformed values. Deficiencies in the other models appear to & from coefficients fit to lake data and from inappropriate model formulation.  相似文献   
406.
麦杆烟雾中半挥发性有机物的定性检测   总被引:1,自引:0,他引:1  
陈小里 《四川环境》1998,17(2):44-47
城郊农村含湿量较高的麦杆就地焚烧,造成环境空气严重污染。本文采用模拟无组织排放污染源TSP采样的方法,通过美国惠普公司生产的气相色谱—质谱联用仪对经前处理的样品进行分离及定性检测,确认了十四种有机化合物  相似文献   
407.
The San Francisco Estuary Regional Monitoring Program (RMP) for Trace Substances is an innovative partnership among a regulatory agency, more than 70 regulated entities, and an independent scientific organization. The institutional arrangement behind the RMP has made the regulatory system increasingly responsive to emerging management needs, particularly with regard to the development of total maximum daily loads and ecosystem impairment assessment. Through multi-agency partnerships within and outside the RMP institutional structure, major information gaps for several pollutants of concern have been narrowed, resulting in a successful consensus-based regulatory approach to managing copper and nickel mass inputs into the Estuary. Short-term research efforts, based upon monitoring results, helped identify the most cost-effective control and remediation options for various bioaccumulative substances. Additionally, adaptive changes to the monitoring program documented the existence of widespread aquatic toxicity in the Estuary that is apparently due to pesticide runoff from agricultural and urban areas. One of the most important contributions of this collaborative monitoring program is the deliberate and systematic adjustment of management and research questions that serve to influence and add relevance to the overall research agenda related to San Francisco Estuary ecosystem assessment.  相似文献   
408.
The purpose of the present study was to evaluate the groundwater contamination due to the construction and operation of the municipal landfill of Amari, Rethymno, Crete. The groundwater flow and leachate transport in the vadose and saturated zones were studied and simulated, using three different models: the one-dimensional groundwater flow and contaminant transport model for the vadose zone Pesticide Root Zone Model (PRZM-3), the Geographical Information System (GIS) Argus ONE and the three-dimensional groundwater flow and contaminant transport model Princeton Transport Code (PTC). The simulation time was 30 and 20 years, and the results obtained, according to the models and the existing hydrogeological conditions, were very encouraging and reassuring about the groundwater quality of the broad region.  相似文献   
409.
建立了加压流体萃取-气相色谱质谱法测定土壤和沉积物中27种拟除虫菊酯类农药的方法。以丙酮/正己烷(V∶V=1∶1)为萃取溶剂,在120℃和10. 3 MPa条件下静态萃取7 min,循环3次,石墨化炭黑串接氨丙基键合硅胶固相萃取柱净化,HP-5MS UI色谱柱分离,优化了提取和分析过程的重要条件。方法检出限为0. 001~0. 012 mg/kg,土壤中低、高浓度的加标回收率范围分别为68. 3%~123%和75. 3%~115%,沉积物中低、高浓度的加标回收率范围分别为67. 1%~120%和78. 6%~110%,单一目标物的相对标准偏差(RSD)均<20%(n=6)。实验结果表明,该方法消耗溶剂少、效率高、检出限低、精密度和准确度好,适用于土壤和沉积物中拟除虫菊酯类农药残留的测定。  相似文献   
410.
试验了用非全量消解—悬浮液直接进样火焰原子吸收光谱法测定煤灰中的铜和铅,结果表明:铜和铅的方法检出限(3σ)分别为0.038mg/L和0.23mg/L,测定吸光度与其浓度的线性范围均为0.5mg/L—5.0mg/L,样品加标回收率在87%—97%之间,相对标准差(n=4)小于7%。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号