全文获取类型
收费全文 | 5056篇 |
免费 | 77篇 |
国内免费 | 51篇 |
专业分类
安全科学 | 285篇 |
废物处理 | 184篇 |
环保管理 | 1078篇 |
综合类 | 630篇 |
基础理论 | 1248篇 |
环境理论 | 3篇 |
污染及防治 | 1146篇 |
评价与监测 | 371篇 |
社会与环境 | 189篇 |
灾害及防治 | 50篇 |
出版年
2024年 | 27篇 |
2023年 | 42篇 |
2022年 | 53篇 |
2021年 | 61篇 |
2020年 | 85篇 |
2019年 | 95篇 |
2018年 | 96篇 |
2017年 | 136篇 |
2016年 | 160篇 |
2015年 | 128篇 |
2014年 | 168篇 |
2013年 | 430篇 |
2012年 | 221篇 |
2011年 | 293篇 |
2010年 | 207篇 |
2009年 | 241篇 |
2008年 | 251篇 |
2007年 | 287篇 |
2006年 | 241篇 |
2005年 | 207篇 |
2004年 | 185篇 |
2003年 | 170篇 |
2002年 | 168篇 |
2001年 | 127篇 |
2000年 | 84篇 |
1999年 | 77篇 |
1998年 | 63篇 |
1997年 | 77篇 |
1996年 | 62篇 |
1995年 | 66篇 |
1994年 | 73篇 |
1993年 | 60篇 |
1992年 | 46篇 |
1991年 | 38篇 |
1990年 | 40篇 |
1989年 | 38篇 |
1988年 | 29篇 |
1987年 | 25篇 |
1986年 | 22篇 |
1985年 | 29篇 |
1984年 | 26篇 |
1983年 | 32篇 |
1982年 | 26篇 |
1981年 | 44篇 |
1980年 | 24篇 |
1979年 | 24篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 13篇 |
排序方式: 共有5184条查询结果,搜索用时 0 毫秒
961.
962.
Michael J. White Daniel E. Storm Michael D. Smolen Hailin Zhang 《Journal of the American Water Resources Association》2009,45(2):397-406
Abstract: Assessment tools to evaluate phosphorus loss from agricultural lands allow conservation planners to evaluate the impact of management decisions on water quality. Available tools to predict phosphorus loss from agricultural fields are either: (1) qualitative indices with limited applicability to address offsite water quality standards, or (2) models which are prohibitively complex for application by most conservation planners. The purpose of this research was to develop a simple interface for a comprehensive hydrologic/water quality model to allow its usage by farmers and conservation planners. The Pasture Phosphorus Management (PPM) Calculator was developed to predict average annual phosphorus (P) losses from pastures under a variety of field conditions and management options. PPM Calculator is a vastly simplified interface for the Soil and Water Assessment Tool (SWAT) model that requires no knowledge of SWAT by the user. PPM Calculator was validated using 33 months of data on four pasture fields in northwestern Arkansas. This tool has been extensively applied in the Lake Eucha/Spavinaw Basin in northeastern Oklahoma and northwestern Arkansas. PPM Calculator allows conservation planners to take advantage of the predictive capacity of a comprehensive hydrologic water quality model typically reserved for use by hydrologists and engineers. This research demonstrates the applicability of existing water quality models in the development of user friendly P management tools. 相似文献
963.
Swine (Sus scofa domestica) lagoon effluent is a valuable resource. In the U.S. Mid-South it is applied from April to September to fertilize grass hay in spray-irrigated fields. Lagoon levels of nutrients and bacteria, and soil levels of nutrients have been documented, but little was known of effluent bacterial levels in soil. The present study examined levels of selected effluent bacteria and nutrients in soils inside and outside spray fields after >15 yr of effluent irrigation. Samples were collected February to March 2009 from contiguous soils spanning adjacent irrigated and nonirrigated areas. Separate soil cores for bacterial and nutrient tests were collected in pairs <10 cm apart. Five cores each were collected at 15-m intervals and combined, respectively, to comprise inside and outside samples from each of 20 soils (four each from five farms/spray fields). Analyses of data combined across all soils showed higher pH and Mehlich-3-extracrable (M3-) P, Mg, K, Na, Cu, and Zn inside than outside spray fields, while total N, total C, M3-Ca, and M3-Mn did not differ. Bacterial levels were higher inside than outside spray fields for heterotrophic plate counts, thermotolerant coliforms, Staphylococcus spp., and Clostridium perfringens, but levels of Escherichia coli and Enterococcus spp. were not different. Cultural presence/absence tests for three pathogens (Listeria spp., Campylobacter spp., and Salmonella spp.) detected only Listeria spp., which did not differ inside (23% positive samples) and outside (28% positive). Molecular tests detected all three pathogens at low levels that were not different inside and outside. We found no evidence of cumulative buildup of Campylobacter spp., Listeria spp., or Salmonela s. in spray field soils. 相似文献
964.
Roger D. Hansen Michael F. Torpy Michael Kemp David Mills 《Journal of the American Water Resources Association》1980,16(5):862-865
ABSTRACT: The authors conducted a mail survey of 600 employers in the government and private sectors who were thought to hire water track environmental engineers. Of a total of 148 respondents, over 80 percent employed a combined total of over 2,800 environmental engineers. The survey addressed two basic questions: (1) what is the quality of graduate education recently trained engineers have received, and (2) what effect does a nonengineering undergraduate degree have on an engineering graduate student's employment potential. In answer to the first question, respondents indicated that engineering graduates were deficient in report writing, business law (contracts and specifications), economics and finance, and practical design. Many employers stated that students could better prepare themselves for employment by (1) obtaining professional experience through internships and summer or part-time jobs, and (2) learning to communicate effectively, both orally and in writing. In answer to the second question, 50 percent of the respondents indicated that engineers without an engineering undergraduate degree would not necessarily be limited in their abilities to perform engineering duties. 相似文献
965.
966.
Kasper Pihl Torben Larsen Inga Laursen Lone Krebs Michael Christiansen 《黑龙江环境通报》2009,29(13):1256-1261
967.
Mr Selwyn H. Roberts Elizabeth Little Merle Vaughan Michael R. Creasy Anthony Jones Teyrnon G. Powell Andrew J. Dawson 《黑龙江环境通报》1993,13(10):971-975
A woman in the 32nd week of pregnancy was referred for investigation because of fetal abnormalities, including an abdominal wall defect, detected by ultrasonography. In view of the increased risk of chromosome abnormality, amniocentesis was performed to enable informed decisions about the management of the pregnancy and delivery to be taken. Cells from the liquor were inoculated into standard lymphocyte culture medium and incubated for 72 h. Slides with a high mitotic index and good quality metaphases, comparable to those from a blood culture, were obtained after harvesting. Cytogenetic analysis showed the karyotype to be 46,XY,—14,+t(13ql4q), which is consistent with Patau's syndrome. This technique appears to be an option for rapid karyotyping in cases of abdominal wall defect, where a chromosomal abnormality is suspected. 相似文献
968.
Bovine Tuberculosis and Badger Culling in England: An Animal Rights-Based Analysis of Policy Options
Steven P. McCulloch Michael J. Reiss 《Journal of Agricultural and Environmental Ethics》2017,30(4):535-550
Bovine tuberculosis (bovine TB) is an important and controversial animal health policy issue in England, which impacts humans, cattle and badgers. The government policy of badger culling has led to widespread opposition, in part due to the conclusions of a large field trial recommending against culling, and in part because badgers are a cherished wildlife species. Animal rights (AR) theorists argue that sentient nonhumans should be accorded fundamental rights against killing and suffering. In bovine TB policy, however, pro-culling actors claim that badgers must be culled to avoid the slaughter of cattle. The first part of the paper compares AR theories of Regan, Francione, Cochrane, Garner and Donaldson and Kymlicka in the context of wildlife species. The second part of the paper applies these AR theories to bovine TB and badger control. AR theories are applied to badger control policy options of (1) do nothing, (2) badger culling, and (3) badger vaccination. We conclude that AR theories are strongly opposed to badger culling. In general, culling is prohibited due to a badger’s right to life and its rights against suffering. The AR theories support a do-nothing, i.e. non-culling, non-vaccination approach to badger control. In the case of the AR theories of Regan and Francione, this is based on abolitionist positions with respect to farming. For Cochrane, Garner, and Donaldson and Kymlicka, the do-nothing policy option is preferred because badger vaccination causes a degree of suffering which generally is not for the individual’s benefit. 相似文献
969.
970.