全文获取类型
收费全文 | 30492篇 |
免费 | 678篇 |
国内免费 | 5566篇 |
专业分类
安全科学 | 1243篇 |
废物处理 | 1574篇 |
环保管理 | 3017篇 |
综合类 | 11738篇 |
基础理论 | 6190篇 |
环境理论 | 8篇 |
污染及防治 | 9257篇 |
评价与监测 | 1549篇 |
社会与环境 | 1498篇 |
灾害及防治 | 662篇 |
出版年
2023年 | 269篇 |
2022年 | 787篇 |
2021年 | 663篇 |
2020年 | 471篇 |
2019年 | 525篇 |
2018年 | 723篇 |
2017年 | 844篇 |
2016年 | 983篇 |
2015年 | 1083篇 |
2014年 | 1509篇 |
2013年 | 2687篇 |
2012年 | 1652篇 |
2011年 | 1941篇 |
2010年 | 1420篇 |
2009年 | 1493篇 |
2008年 | 1634篇 |
2007年 | 1585篇 |
2006年 | 1420篇 |
2005年 | 1102篇 |
2004年 | 935篇 |
2003年 | 1059篇 |
2002年 | 965篇 |
2001年 | 1019篇 |
2000年 | 816篇 |
1999年 | 764篇 |
1998年 | 605篇 |
1997年 | 554篇 |
1996年 | 552篇 |
1995年 | 514篇 |
1994年 | 462篇 |
1993年 | 403篇 |
1992年 | 345篇 |
1991年 | 292篇 |
1990年 | 265篇 |
1989年 | 222篇 |
1988年 | 214篇 |
1987年 | 184篇 |
1986年 | 178篇 |
1985年 | 161篇 |
1984年 | 184篇 |
1983年 | 185篇 |
1982年 | 183篇 |
1981年 | 156篇 |
1980年 | 133篇 |
1979年 | 125篇 |
1978年 | 137篇 |
1977年 | 116篇 |
1976年 | 105篇 |
1975年 | 109篇 |
1974年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 806 毫秒
161.
发光细菌法评价工业废水的毒性 总被引:5,自引:0,他引:5
用发光细菌测定法估算了两城市污水对河道水体污染的分担率,评价了工厂排放废水的毒性,并据此确定了污染源监督管理中应优先治理的工厂(车间)废水。 相似文献
162.
以邢台市环境保护监测站10年来的监测资料为依据,运用单因子比值法,环比发展速率外推法和直线回归法,对地下水环境质量现状及10年的动态变化进行了分析,研究和评述,并对发展趋势做了预测性评价。 相似文献
163.
Methane emissions from natural wetlands 总被引:3,自引:0,他引:3
Zhengping Wang Dong Zeng William H. Patrick Jr. 《Environmental monitoring and assessment》1996,42(1-2):143-161
Methane is considered one of the most important greenhouse gases in the atmosphere. Because of the strict anaerobic conditions required by CH4-generating microorganisms, natural wetland ecosystems are one of the main sources of biogenic CH4. The total natural wetland area is estimated to be 5.3 to 5.7 × 1012 m2, making up less than 5% of the Earth's land surface. However, natural wetland plays a disproportionately large role in CH4 emissions. Wetlands are likely the largest natural sources of CH4 to the atmosphere, accounting for about 20% of the current global annual emission. Out of the total amount of CH4 emitted, northern wetlands contribute 34%, temperate wetlands 5%, and tropical systems about 60%.Because of the unique characteristics and high productivity, wetland ecosystems are important in the global carbon cycle. Natural wetlands are permanently or temporarily saturated. Strict anaerobic conditions consequently develop, which allows methanogenesis to occur. But the thin oxic layer and the oxic plant rhizophere promote activity of CH4-oxidizing bacteria or methanotrophs. Thus, both CH4 formation and consumption in wetland systems are microbiological processes and are controlled by many factors. Eight of the controlling factors, including carbon supply, soil oxidation-reduction status, pH, temperature, vegetation, salinity and sulfate content, soil hydrological conditions and CH4 oxidation are discussed in this paper. 相似文献
164.
Adami G Barbieri P Piselli S Predonzani S Reisenhofer E 《Journal of environmental monitoring : JEM》2000,2(3):261-265
A sediment sampling based on a two-dimensional mapping was performed in the harbour of Trieste (northern Adriatic Sea), considering 28 sites exposed to pollutant inputs from harbour and industrial activities. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined in surface sediments, because these very persistent pollutants seem to be responsible for the depletion of benthic populations observed in this area. The correlation matrix indicates that PAHs and PCBs are non-correlated, and probably have different sources. Both cluster analysis performed on the sampling sites and graphical drawing of the PAH sediment contents make it possible to locate along the shoreline a band of more polluted sediments, clustered around a site facing a steelmaking factory, to be considered as the main source point for PAHs. The evaluation of phenanthrene to anthracene (P/AN) and fluoranthene to pyrene (FL/PY) ratios permits the assessment of the pyrolytic, industrial origin of these PAHs, rejecting a second possible source of hydrocarbons (i.e., an oil-pipeline terminal, situated near the steelmaking factory). Graphical drawing of the total PCB iso-concentrations reveals a different source-point for this other category of very persistent pollutants. 相似文献
165.
用密切值法评价沙湾荒漠区生态环境质量 总被引:3,自引:0,他引:3
利用多目标决策中的密切值法进行沙湾荒漠区生态环境综合评价。该方法简便、适用、且分辨率较高,对各监测点群的定量描述符合实际状况。 相似文献
166.
本文通过对影响街道空气中一氧化碳污染的因素进行了大量的监测及综合分析,找出乌鲁木齐市主要街道空气中一氧化碳的污染规律,为控制我市汽车污染提供科学依据. 相似文献
167.
The composition of precipitation is being monitored in collectors sited throughout the United Kingdom. In the first year, 1986, hydrogen ion, nitrate, ammonium and non-marine sulphate were measured in samples from 47 sites and annual mean concentrations determined. Spatial analysis based on Regionalized Variable Theory revealed autocorrelation in all four ions and reasonable bounded models were fitted to the sample variogram of all four. These were then used to estimate values of a fine mesh grid by simple kriging, and the estimates were then contoured. The estimation errors were similarly mapped, and both sets of maps are presented. The maps show that concentrations of these ions are greatest in eastern parts of the country, as expected from consideration of European emissions and weather patterns. For the first time estimation errors were also mapped and show how the network could be improved. 相似文献
168.
J. E. Elliott D. G. Noble R. J. Norstrom P. E. Whitehead 《Environmental monitoring and assessment》1989,12(1):67-82
Eggs were collected from seven seabird species at colonies on the British Columbia coast from 1983 to 1986 and analyzed for organochlorine contaminants. Total PCB levels (wet weight) were highest in double-crested cormorants (Phalacrocorax auritus) from the Fraser estuary (2.91 mg kg-1) and the Strait of Georgia (3.79 mg kg-1). Highest DDE levels were in fork-tailed storm-petrels (Oceanodroma furcata) from the Queen Charlotte Islands (1.68 mg kg-1). Organochlorine levels were generally lower in eggs from the mid 1980s than in those collected in the early 1970s. Organochlorine levels in Pacific alcids and hydrobatids foraging in offshore locations were compared to those in the same or ecologically similar species from the Canadian Atlantic coast. DDT- and HCH-related compounds were higher in Pacific populations while levels of dieldrin, oxychlordane, and HCB were generally lower. With the exception of -HCH, levels of all measured organochlorines were lower in cormorants breeding in the Fraser River estuary than in cormorants from the St. Lawrence River estuary on the Atlantic coast. 相似文献
169.
David S. Bigelow William S. Ferguson Robert G. Woodmansee 《Environmental monitoring and assessment》1983,3(2):123-131
A second derivative spectrometer custom fitted with a 1 m stainless steel White cell and maintained at 105°C is used to make real-time measurements of volatilized NH3 from urea-amended soil. Comparison of the technique to impinger data shows a 5–16% discrepancy between the two techniques; however, other experiments presented suggests that this is not real. Sulfur dioxide and nitrous oxide interferences are discussed, though they were not found to be present in this study. Instrument response time is shown to be fast if 67% of the total response is achieved in less than 5 min. Fast response is achieved for ammonia if wall-adsorption effects are minimal and if ammonia mass flow is maintained at 0.2 μg min-1. 相似文献
170.
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