全文获取类型
收费全文 | 1834篇 |
免费 | 105篇 |
国内免费 | 576篇 |
专业分类
安全科学 | 134篇 |
废物处理 | 113篇 |
环保管理 | 137篇 |
综合类 | 1055篇 |
基础理论 | 302篇 |
污染及防治 | 550篇 |
评价与监测 | 96篇 |
社会与环境 | 64篇 |
灾害及防治 | 64篇 |
出版年
2024年 | 5篇 |
2023年 | 48篇 |
2022年 | 132篇 |
2021年 | 104篇 |
2020年 | 77篇 |
2019年 | 80篇 |
2018年 | 76篇 |
2017年 | 85篇 |
2016年 | 103篇 |
2015年 | 104篇 |
2014年 | 122篇 |
2013年 | 179篇 |
2012年 | 147篇 |
2011年 | 153篇 |
2010年 | 114篇 |
2009年 | 105篇 |
2008年 | 103篇 |
2007年 | 111篇 |
2006年 | 78篇 |
2005年 | 57篇 |
2004年 | 37篇 |
2003年 | 56篇 |
2002年 | 63篇 |
2001年 | 43篇 |
2000年 | 48篇 |
1999年 | 45篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 25篇 |
1994年 | 12篇 |
1993年 | 25篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1958年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有2515条查询结果,搜索用时 422 毫秒
581.
Dry deposition velocities and fluxes of PM10during Asian dust events over the Yellow Sea from 2001 to 2007 were investigated using observation data in Qingdao, China and Jeju, Korea. The dry deposition velocities of PM10 during dust events over the Yellow Sea ranged from 0.19 to 8.17 cm/sec, with an average of 3.38 cm/sec. Dry deposition fluxes of PM10during dust events over the Yellow Sea were in the range of 68.5–2647.1 mg/(m2·day), with an average of 545.4 mg/(m2·day), which is 2–10 times higher than those reported by other studies for both dust and non-dust periods. It was estimated that 2.6 × 1011–48.7 × 1011g dust particles deposit to the Yellow Sea during dust events through dry deposition every year. Compared with the results in previous studies, it was found that the dry deposition of PM10over the Yellow Sea during dust events in the years with high frequency of dust could account for a large or overwhelming fraction of the annual total dry deposition. Backward air mass trajectory analysis showed that dust events influenced Jeju mainly originated from the desert regions located in Mongolia and Inner Mongolia, China. There were 119 backward trajectories influenced both Qingdao and Jeju during 15 dust events from 2001 to 2007, accounting for 61.3% of the total trajectories of 194, indicating that Qingdao and Jeju were usually on the same pathway of dust transport downwind from source areas. 相似文献
582.
We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides(HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents(denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 μg/L to below 5 μg/L(the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201. 相似文献
583.
584.
长距离原油管道在密闭输送过程中,出现非正常停泵、误关阀门等均会引起水击现象发生,水击波沿管道传播,极易导致管道局部超压而造成管道破裂、设备损坏等事故.鉴于甬沪宁管线落差大、管道水力工况复杂等特点,分析水击现象的产生并加以防范是十分必要的. 相似文献
585.
586.
2-Trifluoromethylphenol was hydrolysed in a phosphate buffer at neutral pH. At mild temperatures ranging from 34 degrees C to 69 degrees C this compound liberates consecutively fluorine anions to form salicylic acid. This process is energetically driven by the hydration of the fluorine anions. No intermediates have been detected by HPLC and (19)F-NMR and this was confirmed by computer calculations which favor the first step in the whole reaction sequence being rate-limiting. Accordingly, the reaction energy of the first dehalogenation of the trifluoromethyl anion is 28.4 kcal mol(-1) higher than for the second dehalogenation. The pseudo-first-order kinetic was determined and from an Arrhenius diagram an activation energy of E(a)=25.1 kcal mol(-1) has been estimated. At 37 degrees C and a pH of 7.4 the half-life was 6.9 h. The rate of hydrolysis was favored at higher pH and it was not influenced by oxygen, sunlight or trace elements found in natural water. The latter was shown by incubations with lake water instead of distilled water. 相似文献
587.
The aim of this study was to assess the total concentration and health risk to infants of breast milk mercury in urban mothers and mothers married to fishermen in relation to fish intake in Taiwan. A total of sixty-eight healthy mothers were recruited for the study. The breast milk mercury geometric mean concentration was 2.02 microgl(-1) (n=56, range: 0.24-9.45 microgl(-1)) for the city group and 2.04 microgl(-1) (n=12, range: 0.26-8.62 microgl(-1)) for the fishermen's group. Of the three sources of mercury exposure (i.e., ingestion (breast milk), inhalation (ambient air), and dermal exposure (shower)), breast-feeding was found to be the largest (96.3-99.6% of the total). From a Monte Carlo simulation, in which methyl mercury accounted for about 50% of total mercury, the hazard quotient (exposure estimate/oral minimal risk level or target organ toxicity dose) exceeded 1.0 for 12.9% of urban babies and 18.8% of fishermen's babies (chronic oral minimal risk level and target organ toxicity dose: 3 x 10(-4)mgkg(-1)d(-1)). The calculated mercury exposure was 3.02 x 10(-1) microgkg(-1)d(-1) for a 3.49 kg urban baby boy and 3.06 x 10(-1) microgkg(-1)d(-1) for a 3.44 kg urban baby girl. These results suggest the life style of mothers (eating raw fish and shellfish such as used in "Sashimi" and "Sushi," and vitamin supplementation) may influence the mercury concentration in breast milk. 相似文献
588.
589.
本文主要对近30年来营口地震台记录的海城7.3级地震的余震观测资料进行分析,按不同的震级进行统计,分别作出M-T图和N-T图,可供今后监测工作参考。 相似文献
590.
阐述了劳动安全卫生标准体系研究的目的与意义,分析比较了劳动安全卫生标准分类的几种可能方案,着重讨论并提出整个劳动安全卫生标准体系的层次结构方框图。 相似文献