全文获取类型
收费全文 | 402篇 |
免费 | 17篇 |
国内免费 | 150篇 |
专业分类
安全科学 | 37篇 |
废物处理 | 18篇 |
环保管理 | 30篇 |
综合类 | 207篇 |
基础理论 | 71篇 |
污染及防治 | 154篇 |
评价与监测 | 18篇 |
社会与环境 | 22篇 |
灾害及防治 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 27篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 28篇 |
2015年 | 19篇 |
2014年 | 25篇 |
2013年 | 50篇 |
2012年 | 30篇 |
2011年 | 31篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 24篇 |
2007年 | 25篇 |
2006年 | 37篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 14篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有569条查询结果,搜索用时 0 毫秒
1.
选用0.1μm的PVDF中空纤维内压式微滤膜组件,在死端微滤工况下,研究了酵母(平均粒径5.3μm)和高岭土(平均粒径0.7μm)体系在浓度和压力变化时的污染机理及过滤阻力、膜渗透通量的变化规律性。通过恒压堵塞定律积分式的具体形式与实验数据的拟合及根据堵塞过滤定律计算的结果都表明:死端微滤时,酵母体系和高岭土体系均符合滤饼过滤机理。 相似文献
2.
Abstract Land-use change is an important aspect of global environment change. It is, in a sense, the direct result of human activities influencing our physical environment. This paper analyzed the land- use change in Northeast China during 1985–2000 based on Landsat TM images. It divides Northeast China into five land-use zones based on the dynamic degree model of land-use: woodland/grassland-arable land conversion zone, dry land-paddy field conversion zone; urban expansion zone, interlocked zone of farming and pasturing and reclamation and abandon zone. The findings include the obvious increase of cropland area, paddy field and dry land increased by 75 and 276 thousand hm2 respectively; urban areas expanded rapidly, areas of town and rural residence increased by 76.8 thousand hm2; areas of forests and grassland decreased sharply with the amounts of 1399 and 1521 thousand hm2 respectively; areas of water body and unused land increased by 148 and 514 thousand hm2 respectively. This paper also discusses the driving forces in each land-use dynamic zone and finds that some key biophysical factors affect conspicuously the conversion of different land-use types. The relation between land-use conversion and DEM, accumulated temperature (≤10°C) and precipitation was analyzed and represented. The land-use changes In Northeast China resulted from the changing macro social and economic factors and local physical elements. Rapid population growth and management changes can explain the shaping of woodland/grassland-cropland conversion zone. The conversion from dry land to paddy field in the dry land-paddy field conversion zone, apart from the change of physical elements promoting the expansion of paddy field, results from two reasons: one is that the implementation of market economy in China has given farmers the right to decide what and how they plant their crops, the other factor is originated partially from the change of the dietary habit along with the social and economic development. The conversion from paddy field to dry land is caused primarily by the shortfall of irrigation water, which in turn is caused by poor water allocation managed by local governments. The shaping of the reclamation and abandon zone is partially due to the lack of environment protection consciousness among pioneer settlers. The reason for the conversion from grassland to cropland is the relatively higher profits of farming than that of pasturing in the interlocked zone of farming and pasturing. In Northeast China, the rapid expansion of built-up areas results from two factors: the existence of a small number of towns and the huge potential for expansion of the existing towns and cities. The urban land expanded mainly in areas with a gentle topographic relief and low population density. 相似文献
3.
4.
沉淀—树脂吸附法处理对氨基偶氮苯盐酸盐生产废水的研究 总被引:3,自引:0,他引:3
对氨基偶氮苯盐酸盐(PABS)是生产染料的重要中间体。在PABS生产过程中,排放出高浓度(COD4万~8万mg/L)、高色度(4万~8万)、高毒性(含苯胺和对氨基偶氮苯)和高氯(Cl-4万~10万mg/L)的废水。利用中和沉淀—大孔吸附树脂吸附法进行了处理工艺的小试研究。结果表明,废水色度去除率达到999%,降到20以下;出水中基本不含对氨基偶氮苯(PAB);出水中苯胺的浓度降到3mg/L。GC/MS分析的结果表明,乙醇脱附液中苯胺是最主要的有机物,所以利用该工艺能实现苯胺的回收。 相似文献
5.
6.
采用体内试验和体外试验方法,观察氯化镉对小鼠免疫功能的影响。免疫后不同时间,给小鼠一次灌胃30mg/kgCdCl2,未见对免疫功能产生明显影响。反复多次灌胃染毒14天,在0.3mg/ks/d组可见明显抑制小鼠脾淋巴细胞IgM-pFC,抑制率为42.1%。体外试验表明,12.5μmol/LCdCl2与淋巴细胞作用48h,25μmol/LCdCl2作用72h,对淋巴细胞增殖反应抑制率分别为38.3%和77.8%,以上结果表明氟化钢具有明显的免疫毒性。 相似文献
7.
Yanhui Zhan Jianwei Lin Yanling Qiu Naiyun Gao Zhiliang Zhu 《Frontiers of Environmental Science & Engineering in China》2011,5(1):65-75
Surfactant-modified natural zeolites (SMNZ) with different coverage types were prepared by loading hexadecyltrimethyl ammonium
bromide (HTAB) onto the surface of a natural zeolite. The adsorption behavior of humic acid (HA) on SMNZ was investigated.
Results indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural zeolite. HA removal efficiency
by SMNZ increased with HTAB loading. Coexisting Ca2+ in solution favored HA adsorption onto SMNZ. Adsorption capacity decreased with an increasing solution pH. For typical SMNZ
with bilayer HTAB coverage, HA adsorption process is well described by a pseudo-second-order kinetic model. The experimental
isotherm data fitted well with the Langmuir model. Calculated maximum HA adsorption capacities for SMNZ with bilayer HTAB
coverage at pH 5.5 and 7.5 were 63 and 41 mg·g−1, respectively. E2/E3 (absorbance at 250 nm to that at 365 nm) and E4/E6 (absorbance at 465 nm to that at 665 nm) ratios of
the residual HA in solution were lower than that of the original HA solution. This indicates that the HA fractions with high
polar functional groups, low molecular weight (MW), and aromaticity had a stronger tendency for adsorption onto SMNZ with
bilayer HTAB coverage. Results show that HTAB-modified natural zeolite is a promising adsorbent for removal of HA from aqueous
solution. 相似文献
8.
Rongchang WANG Xinmin ZHAN Yalei ZHANG Jianfu ZHAO 《Frontiers of Environmental Science & Engineering》2011,5(1):48-56
Nitrogen removal performance and nitrifying population dynamics were investigated in a redox stratified membrane biofilm reactor (RSMBR) under oxygen limited condition to treat ammonium-rich wastewater. When the N H 4 + - N loading rate increased from 11.1±1.0 to 37.2 ± 3.2 g N H 4 + - N · m - 2 · d - 1 , the nitrogen removal in the RSMBR system increased from 18.0±9.6 mgN·d-1 to 128.9±61.7 mgN·d-1. Shortcut nitrogen removal was achieved with nitrite accumulation of about 22.3 ± 5.3 m g N O 2 - - N · L - 1 . Confocal micrographs showed the stratified distributions of nitrifiers and denitrifiers in the membrane aerated biofilms (MABs) at day 120, i.e., ammonia and nitrite oxidizing bacteria (AOB and NOB) were dominant in the region adjacent to the membrane, while heterotrophic bacteria propagated at the top of the biofilm. Real-time qPCR results showed that the abundance of amoA gene was two orders of magnitude higher than the abundance of nxrA gene in the MABs. However, the nxrA gene was always detected during the operation time, which indicates the difficulty of complete washout of NOB in MABs. The growth of heterotrophic bacteria compromised the dominance of nitrifiers in biofilm communities, but it enhanced the denitrification performance of the RSMBR system. Applying a high ammonia loading together with oxygen limitation was found to be an effective way to start nitrite accumulation in MABs, but other approaches were needed to sustain or improve the extent of nitritation in nitrogen conversion in MABs. 相似文献
9.
10.