全文获取类型
收费全文 | 10771篇 |
免费 | 1402篇 |
国内免费 | 6024篇 |
专业分类
安全科学 | 1819篇 |
废物处理 | 341篇 |
环保管理 | 1077篇 |
综合类 | 10017篇 |
基础理论 | 2076篇 |
环境理论 | 2篇 |
污染及防治 | 1523篇 |
评价与监测 | 695篇 |
社会与环境 | 417篇 |
灾害及防治 | 230篇 |
出版年
2024年 | 53篇 |
2023年 | 427篇 |
2022年 | 623篇 |
2021年 | 678篇 |
2020年 | 702篇 |
2019年 | 692篇 |
2018年 | 576篇 |
2017年 | 563篇 |
2016年 | 641篇 |
2015年 | 777篇 |
2014年 | 672篇 |
2013年 | 1136篇 |
2012年 | 1157篇 |
2011年 | 1221篇 |
2010年 | 816篇 |
2009年 | 943篇 |
2008年 | 766篇 |
2007年 | 911篇 |
2006年 | 910篇 |
2005年 | 667篇 |
2004年 | 551篇 |
2003年 | 496篇 |
2002年 | 361篇 |
2001年 | 310篇 |
2000年 | 279篇 |
1999年 | 227篇 |
1998年 | 162篇 |
1997年 | 162篇 |
1996年 | 123篇 |
1995年 | 128篇 |
1994年 | 86篇 |
1993年 | 79篇 |
1992年 | 54篇 |
1991年 | 27篇 |
1990年 | 28篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 8篇 |
1986年 | 14篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1971年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
81.
Fagundez LA Fernández VL Marino TH Martín I Persano DA Rivarola Y Benítez M Sadañiowski IV Codnia J Zalts A 《Environmental monitoring and assessment》2001,71(1):61-70
Passive diffusion samplers were employed in San Miguel(Buenos Aires Metropolitan Area) for a preliminary airpollution monitoring. The highest loads were observedin downtown, compared with an urban background site.Total suspended particulate matter (TSPM) varied from0.257 to 0.033 mg cm-2 month-1; dust was examinedfor particle nature and size distribution. A similartrend was observed for nitrogen dioxide (NO2) andTSPM spatial distribution, suggesting that traffic isthe major pollution source. Sulphur dioxide (SO2)values were low and rather homogeneous. Levels for theinvestigated pollutants are below EPA's guide linevalues. Geographic (flat area, near to Rio de LaPlata) and climatologic factors (rainfalls andvariable wind directions) contribute to disperse pollutants. 相似文献
82.
用工业废水排放量预测地面水CODMn灰色方法研究 总被引:2,自引:0,他引:2
GPM(1)灰色生长曲线常被用于等距时序环境系统的分析建模、非等距摆动空间序列方面的应用尚未报道。本文研究提出了将非等距摆动空间序列经过等距化处理的GPM(1)线性回归优化建模方法采用该方法所建的非等距GPM(1)模型用于工业废水量预测地面水CODMn的实例表明,该方法简捷,方便、精度高于回归分析,有较大实用价值。 相似文献
83.
During the summers of 1991–1994, the Environmental Monitoringand Assessment Program (EMAP) sampled 344 lakes throughout thenortheastern United States using a proportional stratified sampling design based on lake size. Approximately one-quarter ofthe 344 lakes were sampled each year (4 years) for totalphosphorus to determine the proportion (and associated95% confidence intervals) of the northeast lake population 1ha (11,076 ± 1,699 lakes) that was in oligotrophic,mesotrophic, eutrophic, or heupereutropic (4 classes) conditionaccording to the total phosphorus criteria of the North AmericaLake Manegement Society. Estimates for the second, third, andfourth yr were developed as cumulative of the previous yrsamples and the current yr samples for the northeast as a wholeand for each of its three ecoregions (4 regions). New confidence intervals were computed for each cumulative yrcondition estimate. This produced a total (4 years × 4classes × 4 regions) of 64 cumulative yr tropic conditionestimates. Confidence intervals for 21% of these estimates didnot shorten with increased sample size. This phenomena raisedquestions about the accuracy of estimates based on cumulativesampling procedures. We explain why and how the phenomenon comesabout with both straight random and proportional randomsampling. Further, we present an example of the effects thisphenomenon has on lake tropic state condition estimates in thenortheastern United States. 相似文献
84.
根据塔里木油田1993-1996年环境空气监测数据,对其环境空气质量状况进行了分析和评价。 相似文献
85.
博斯腾湖富营养化状态水平调查 总被引:1,自引:0,他引:1
通过水质特征和生物学特征的一个水文年规范化实地调查,采用Scirgesew参数分类标准和相关加权综合营养状态指数,对博斯腾湖水体富营养化状态水平进行了调查和评价。 相似文献
86.
运用灰色系统理论,结合实例详细介绍了GM(1,1)模型在大气环境浓度预测中的应用。 相似文献
87.
对GAM水环境预测模型提出了四点不同看法,与有关作者商榷,指出GM(1,1)模型与GAM模型二者并无优劣之差,精度亦相当。 相似文献
88.
唐山市空气中SO2与TSP污染状况分析 总被引:1,自引:0,他引:1
分析了唐山市从1988年至1992年大气中SO2和TSP的污染状况和变化规律,取得对该市环境管理的科学依据。 相似文献
89.
Ports can generate large quantity of pollutants in the atmosphere due to various activities like loading and unloading,transportation, and construction operations. Determination of the character and quantity of emissions from individual sources is an essential step in any project to control and minimize the emissions.In this study a detailed emission inventory of total suspendedparticulate matter (TSP), particulate matter less than 10 m(PM10), sulfur dioxide (SO2) and nitrogen oxides (NOx) for a port and harbour project near Mumbai is compiled. Results show that the total annual average contributions of TSP and PM10 from all the port activitieswere 872 and 221 t yr-1, respectively. Annual average emissions of gaseous pollutants SO2 and NOxwere 56 and 397 t yr-1, respectively, calculatedby using emission factors for different port activities. The maximum TSP emission (419 t yr -1) was from paved roads, while the least (0.4 t yr-1) was from bulk handling activity. The maximum PM10 emission (123 t yr-1) was from unpaved roads and minimum (0.2 t yr-1) from bulk handling operations. Similarly the ratio of TSP and PM10 emission was highest (5.18) from paved roads and least (2.17) from bulk handling operations. Regression relation was derivedfrom existing emission data of TSP and PM10 from variousport activities. Good correlation was observed between TSP andPM10 having regression coefficient >0.8. 相似文献
90.
氢化物发生原子荧光法测定饮用水中的微量硒时。仪器条件和试剂的浓度选择很重要。本文对条件的最佳化进行了实验。并对方法的精密度、准确度和检出限进行了讨论。 相似文献