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   20717篇
  免费   180篇
  国内免费   132篇
安全科学   536篇
废物处理   986篇
环保管理   2525篇
综合类   2813篇
基础理论   5341篇
环境理论   4篇
污染及防治   5598篇
评价与监测   1651篇
社会与环境   1453篇
灾害及防治   122篇
  2023年   119篇
  2022年   221篇
  2021年   235篇
  2020年   167篇
  2019年   206篇
  2018年   327篇
  2017年   323篇
  2016年   533篇
  2015年   375篇
  2014年   580篇
  2013年   1750篇
  2012年   678篇
  2011年   869篇
  2010年   803篇
  2009年   788篇
  2008年   891篇
  2007年   978篇
  2006年   873篇
  2005年   724篇
  2004年   728篇
  2003年   708篇
  2002年   673篇
  2001年   916篇
  2000年   633篇
  1999年   400篇
  1998年   279篇
  1997年   251篇
  1996年   296篇
  1995年   275篇
  1994年   252篇
  1993年   236篇
  1992年   245篇
  1991年   210篇
  1990年   220篇
  1989年   219篇
  1988年   197篇
  1987年   158篇
  1986年   126篇
  1985年   138篇
  1984年   169篇
  1983年   153篇
  1982年   193篇
  1981年   134篇
  1980年   119篇
  1979年   152篇
  1978年   118篇
  1977年   107篇
  1976年   100篇
  1975年   83篇
  1974年   88篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
    
The “Bayes‐type” method of deriving change‐point test statistics was introduced by Chernoff and Zacks (1964). Other authors subsequently adapted this approach and derived Bayes‐type statistics for at most one change (AMOC), and for multiple change points, under a variety of model formulations. Asymptotic distribution theory has always been limited to the AMOC statistics because of the perceived complexity of multiple change‐point statistics. In this article, it is shown that the Bayes‐type statistic derived to test for multiple change points is directly proportional to the AMOC statistic. This result immediately provides distributional results for Bayes‐type multiple change‐point statistics. In addition, it fundamentally alters the current understanding of the AMOC statistic. It follows from this result that the Bayes‐type statistic derived under AMOC conditions in fact tests for at least one change (ALOC), even though the statistic is derived under AMOC formulation. Under asymptotic consideration, the result also extends to the case of model errors following a stationary process. As an example, the classical Nile River data are revisited and analyzed for the presence of multiple change points.  相似文献   
942.
943.
944.
945.
946.
    
Decades of research in spatial statistics have prompted the development of a wide variety of models and methods whose primary goal is optimal linear interpolation (kriging), as well as sound assessment of the associated uncertainty (kriging variance). While kriging is of paramount importance for scientific investigations requiring high‐resolution maps, spatial statistics can be used for other classes of applications as well. Indeed, new areas are emerging where the main goal is to simulate from a statistical model whose parameters have been estimated from the data. This paper focuses on two different ways to model global data with axially symmetric Gaussian processes, for which the covariance function is nonstationary over latitudes and stationary over longitudes. Both strategies are illustrated through a global data set on surface temperatures generated by the National Center for Atmospheric Research (NCAR). On the one hand, we downscale surface temperatures through a classical geostatistical approach. We exploit Gaussianity assumption to focus on the second‐order structure, and we develop a novel class of axially symmetric models inspired from currently available isotropic models. We also propose a new covariance model that is axially symmetric. Covariance‐based approaches are notorious for their computational burden, and a considerable amount of recent literature has been devoted to overcome this problem. We propose a simulation‐based approach that works for processes defined on a lattice only. For such an approach, kriging cannot be performed as there is an underlying continuous process. At the same time, inference can be performed exactly on extremely large data sets.  相似文献   
947.
948.
949.
    
CarbFix, a combined industrial‐academic pilot program, was developed in order to assess the feasibility of in situ CO2 mineral sequestration in basaltic rocks. Unique to CarbFix is its connection to the Hellisheidi geothermal power plant, allowing for capture of otherwise emitted CO2 in addition to CO2 transport and mineral sequestration. Extensive research has been conducted in order to characterize physical properties of the pilot injection site in Hellisheidi. Tracer tests have been carried out and continuous well‐logging confirmed separation of the target formation from shallower groundwater systems. Alteration mineralogy in natural analogs has been mapped out in order to predict which minerals are likely to precipitate upon CO2 injection. In addition to carbonates, these include clays, zeolites, and poorly crystalline hydroxides. Some of the secondary minerals will compete with carbonates for cations dissolved from the rock matrix. Numerical modeling plays an important role in the CarbFix project as it provides tools to predict and optimize long‐term management of the injection site as well as to quantify the amount of CO2 that can be mineralized. A reactive transport model has been developed and numerical simulations of the pilot CO2 injection are ongoing. Extensive monitoring provides the basis for testing, validating, and calibrating reactive transport models. It is anticipated that the results of CarbFix will be used to optimize the in situ carbon mineralization process, enabling it in basalt and ultramafic rock formations throughout the world. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd  相似文献   
950.
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