全文获取类型
收费全文 | 195篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 5篇 |
环保管理 | 68篇 |
综合类 | 16篇 |
基础理论 | 37篇 |
污染及防治 | 35篇 |
评价与监测 | 15篇 |
社会与环境 | 5篇 |
灾害及防治 | 5篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 1篇 |
2013年 | 21篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有200条查询结果,搜索用时 31 毫秒
51.
52.
Accuracy Assessment of NOAA Gridded Daily Reference Evapotranspiration for the Texas High Plains
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jerry Moorhead Prasanna Gowda Mike Hobbins Gabriel Senay George Paul Thomas Marek Dana Porter 《Journal of the American Water Resources Association》2015,51(5):1262-1271
The National Oceanic and Atmospheric Administration (NOAA) provides daily reference evapotranspiration (ETref) maps for the contiguous United States using climatic data from North American Land Data Assimilation System (NLDAS). This data provides large‐scale spatial representation of ETref, which is essential for regional scale water resources management. Data used in the development of NOAA daily ETref maps are derived from observations over surfaces that are different from short (grass — ETos) or tall (alfalfa — ETrs) reference crops, often in nonagricultural settings, which carries an unknown discrepancy between assumed and actual conditions. In this study, NOAA daily ETos and ETrs maps were evaluated for accuracy, using observed data from the Texas High Plains Evapotranspiration (TXHPET) network. Daily ETos, ETrs and the climatic data (air temperature, wind speed, and solar radiation) used for calculating ETref were extracted from the NOAA maps for TXHPET locations and compared against ground measurements on reference grass surfaces. NOAA ETref maps generally overestimated the TXHPET observations (1.4 and 2.2 mm/day ETos and ETrs, respectively), which may be attributed to errors in the NLDAS modeled air temperature and wind speed, to which reference ETref is most sensitive. Therefore, a bias correction to NLDAS modeled air temperature and wind speed data, or adjustment to the resulting NOAA ETref, may be needed to improve the accuracy of NOAA ETref maps. 相似文献
53.
Identifying and Evaluating a Suitable Index for Agricultural Drought Monitoring in the Texas High Plains
下载免费PDF全文
![点击此处可从《Journal of the American Water Resources Association》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jerry E. Moorhead Prasanna H. Gowda Vijay P. Singh Dana O. Porter Thomas H. Marek Terry A. Howell B.A. Stewart 《Journal of the American Water Resources Association》2015,51(3):807-820
Drought is a complex and highly destructive natural phenomenon that affects portions of the United States almost every year, and severe water deficiencies can often become catastrophic for agricultural production. Evapotranspiration (ET) by crops is an important component in the agricultural water budget; thus, it is advantageous to include ET in agricultural drought monitoring. The main objectives of this study were to (1) conduct a literature review of drought indices with a focus to identify a simple but simultaneously adequate drought index for monitoring agricultural drought in a semiarid region and (2) using the identified drought index method, develop and evaluate time series of that drought index for the Texas High Plains. Based on the literature review, the Standardized Precipitation‐Evapotranspiration Index (SPEI) was found to satisfy identified constraints for assessing agricultural drought. However, the SPEI was revised by replacing reference ET with potential crop ET to better represent actual water demand. Data from the Texas High Plains Evapotranspiration network was used to calculate SPEIs for the major irrigated crops. Trends and magnitudes of crop‐specific, time‐series SPEIs followed crop water demand patterns for summer crops. Such an observation suggests that a modified SPEI is an appropriate index to monitor agricultural drought for summer crops, but it was found to not account for soil water stored during the summer fallow period for winter wheat. 相似文献
54.
Acknowledgement to referees
Acknowledgement to referees 相似文献55.
Rolando Bravo Jerry R. Rogers Theodore G. Cleveland 《Journal of the American Water Resources Association》1996,32(1):39-46
ABSTRACT: Determination of the boundary conditions for modeling ground water flow is a critical point especially in regional models. Normally the regional models require model areas that are greater than the given area of interest. This work focuses on the prediction of hydraulic heads in regional models using flux boundary conditions. The model uses flux boundary conditions that were estimated using a radial flow analog and Darcy's law. The regional model that is presented uses no parameter identification (inverse estimation) procedures. In the present work, the Houston area was used. The simulation of the hydrological conditions of the Chicot and Evangeline Aquifers that underlie the Houston area were made using the available information about the geological profile in the Houston region and the current information about the existing production wells. The regional model works as a forward problem. The system parameters such as hydraulic conductivity, specific storage, and hydrological stresses were specified, and the model predicts the hydraulic head. Actual data from piezometers operated by the U.S. Geological Survey (USGS) in many places throughout Houston were used as initial conditions. Some piezometric head data were generated using the regional variable theory called kriging to supply head estimates in areas where data were unavailable. The Modular Three Dimensional Finite Difference Groundwater Flow Model developed by the USGS was used to predict the hydraulic heads. The predicted ground water heads are compared to the actual data. The results show that the model performs well for locations where data were available. 相似文献
56.
57.
Given the difficulty, as well as the high cost, of siting and constructing municipal solid waste (MSW) landfills it is incumbent on landfill managers to evaluate all practical measures to extend the useful life of existing landfills. This necessitates not only identifying potential methods to extend their life, but also the means to assess at what time horizons in the landfill's life such measures are cost effective. Some typical examples of methods to extend their life include: size reduction of incoming waste, improved in-place compaction density, use of alternative daily cover, waste diversion, and accelerating the degradation to enhance attendant settlement on the MSW. Most, if not all, of these methods incur capital/operating costs that must be evaluated. The methodology for this analysis is presented using the existing landfill at Andersen Air Force Base (AAFB), Guam, as a model for the procedure. The Landfill Extension Model (LEM) computer program was written to model the AAFB landfill and to analyze various extension alternatives to include compaction, shredding, alternative daily cover and operation outsourcing (contracting). The LEM computer program may be used to evaluate any landfill operation and is consequently useful for evaluating any existing landfill. It was found that by utilizing all of the proposed alternatives the life of AAFB landfill could be extended from 10 years to 48 years. 相似文献
58.
Fatal and non-fatal falls from elevation have been documented to be a significant issue. Historically, roofing work has been ranked among the highest in incidents of falls. Recent literature has indicated that exposure to inclined surfaces (roof) has a detrimental effect on postural stability. The purpose of this preliminary study was to determine if postural instability was found to increase following extended exposure to an inclined surface. Twenty-three participants were pre/post tested under four postural stability conditions while varying duration exposure (0.0–2.0 h) to an inclined surface. Dependent variable postural sway measures were calculated from center of pressure data derived from a portable force plate. The results indicate significant differences between pre and post-exposure measures. Specifically, the results imply that an individual is less stable directly after performing tasks on an inclined surface. These findings contribute to the literature and serve as a basis for further research into work rest cycles for those individuals who routinely work on inclined surfaces. 相似文献
59.
Coaching interviewees to perform in employment interviews can influence the interview scores. We describe different types of coaching, emphasizing interventions designed to focus interviewees on core, interview‐relevant content and to help them convey the content accurately (as opposed to interventions designed to teach interviewees to manipulate their scores using peripheral means). We then study the effects of the former type of intervention in relation to the criterion‐related validity of a structured employment interview. In a combined sample of 146 public safety job incumbents, a predictive validation study was conducted using scores from a situational panel interview. Predictive validity and reliability was observed to be higher in a sample of coached interviewees compared to a sample of uncoached interviewees. Implications for future research and practice in organizational behavior are discussed. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
60.
Vanessa Cheesbrough Kurt A. Rosentrater Jerry Visser 《Journal of Polymers and the Environment》2008,16(1):40-50
Interest in renewable biofuel sources has intensified in recent years, leading to greatly increased production of ethanol
and its primary coproduct, Distillers Dried Grain with Solubles (DDGS). Consequently, the development of new outlets for DDGS
has become crucial to maintaining the economic viability of the industry. In light of these developments, this preliminary
study aimed to determine the suitability of DDGS for use as a biofiller in low-cost composites that could be produced by rapid
prototyping applications. The effects of DDGS content, particle size, curing temperature, and compression on resulting properties,
such as flexural strength, modulus of elasticity, water activity, and color were evaluated for two adhesive bases. The composites
formed with phenolic resin glue were found to be greatly superior to glue in terms of mechanical strength and durability:
resin-based composites had maximum fiber stresses of 150–380 kPa, while glue composites had values between 6 kPa and 35 kPa;
additionally, glue composites experienced relatively rapid microbial growth. In the resin composites, both decreased particle
size and increased compression resulted in increased mechanical strength, while a moderate DDGS content was found to increase
flexural strength but decrease Young’s modulus. These results indicate that DDGS has the potential to be used in resin glue-based
composites to both improve flexural strength and improve potential biodegradability. 相似文献