全文获取类型
收费全文 | 1146篇 |
免费 | 8篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 18篇 |
废物处理 | 45篇 |
环保管理 | 70篇 |
综合类 | 667篇 |
基础理论 | 140篇 |
污染及防治 | 167篇 |
评价与监测 | 32篇 |
社会与环境 | 18篇 |
灾害及防治 | 2篇 |
出版年
2017年 | 14篇 |
2015年 | 10篇 |
2014年 | 10篇 |
2013年 | 39篇 |
2012年 | 33篇 |
2011年 | 30篇 |
2010年 | 22篇 |
2009年 | 28篇 |
2008年 | 23篇 |
2007年 | 26篇 |
2006年 | 29篇 |
2005年 | 32篇 |
2004年 | 37篇 |
2003年 | 33篇 |
2002年 | 27篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1998年 | 11篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1989年 | 9篇 |
1978年 | 10篇 |
1966年 | 10篇 |
1965年 | 15篇 |
1964年 | 15篇 |
1963年 | 25篇 |
1962年 | 17篇 |
1961年 | 14篇 |
1960年 | 23篇 |
1959年 | 24篇 |
1958年 | 15篇 |
1957年 | 16篇 |
1956年 | 15篇 |
1955年 | 27篇 |
1954年 | 33篇 |
1953年 | 19篇 |
1952年 | 14篇 |
1951年 | 24篇 |
1948年 | 9篇 |
1947年 | 11篇 |
1941年 | 9篇 |
1939年 | 9篇 |
1938年 | 12篇 |
1935年 | 8篇 |
1933年 | 9篇 |
1931年 | 11篇 |
1930年 | 12篇 |
1929年 | 13篇 |
1921年 | 8篇 |
排序方式: 共有1159条查询结果,搜索用时 578 毫秒
811.
Ge Sun Hans Riekerk Nicholas B. Comerford 《Journal of the American Water Resources Association》1998,34(4):827-841
ABSTRACT: Few hydrological models are applicable to pine flat-woods which are a mosaic of pine plantations and cypress swamps. Unique features of this system include ephemeral sheet flow, shallow dynamic ground water table, high rainfall and evapotranspiration, and high infiltration rates. A FLATWOODS model has been developed specifically for the cypress wetland-pine upland landscape by integrating a 2-D ground water model, a Variable-Source-Area (VAS)-based surface flow model, an evapotranspiration (ET) model, and an unsaturated water flow model. The FLATWOODS model utilizes a distributed approach by dividing the entire simulation domain into regular cells. It has the capability to continuously simulate the daily values of ground water table depth, ET, and soil moisture content distributions in a watershed. The model has been calibrated and validated with a 15-year runoff and a four-year ground water table data set from two different pine flat woods research watersheds in northern Florida. This model may be used for predicting hydrologic impacts of different forest management practices in the coastal regions. 相似文献
812.
813.
An exploratory field study conducted in Europe and the U.S. examines the challenges of managing environmental quality at the enterprise level. The results show that effective environmental quality management depend to a considerable degree on the ability to deal with the multidisciplinary organizational, technical, social, and cultural issues involved in the integration of environmental cost accounting at the enterprise level. The study suggests that the tools and techniques of modern project management can provide an important framework for developing and implementing environmental quality control systems. The recommendations put considerable emphasis on the human side, focusing on the criteria under which environmental quality is best achievable. Strong senior management leadership, people skills, organizational linkages, and alliances, all are critical for dealing with the complexities of managing responsibly toward sustained developments in today’s organizations. 相似文献
814.
Hans G. Wallraff 《Die Naturwissenschaften》1988,75(8):380-392
Pigeon homing, investigated as a paradigmatic example of bird navigation, appears to be based on two mechanisms of orientation whose functions correspond to those of map and compass. Tasks of the latter are usually accomplished by a sun compass, taking into account the sun's movement and time of day. Under overcast skies, the magnetic field of the earth may be used for compass orientation. The "map" part of the system, responsible for site localization, makes use of olfactory perception of atmospheric trace compounds, which must be concluded to contain positional information in unfamiliar areas up to several hundreds of kilometers from home. 相似文献
815.
816.
817.
818.
Hans Grisebach 《Die Naturwissenschaften》1977,64(12):619-625
The complete set of enzymes that catalyze the reactions from l-phenylalanine to substituted cinnamyl alcohols is now known. The latter compounds are the primary building stones of lignin. The individual reactions and the possible modes of regulation of this pathway are discussed. The polymerization of cinnamyl alcohols to lignin is mediated by peroxidase. The significance of cell-wall-bound peroxidases in this process and the origin of hydrogen peroxide are reviewed. Finally, the possible role of lignification in relation to disease resistance is discussed. 相似文献
819.
820.