全文获取类型
收费全文 | 2534篇 |
免费 | 77篇 |
国内免费 | 870篇 |
专业分类
安全科学 | 185篇 |
废物处理 | 150篇 |
环保管理 | 204篇 |
综合类 | 1257篇 |
基础理论 | 438篇 |
污染及防治 | 902篇 |
评价与监测 | 125篇 |
社会与环境 | 96篇 |
灾害及防治 | 124篇 |
出版年
2024年 | 1篇 |
2023年 | 42篇 |
2022年 | 119篇 |
2021年 | 92篇 |
2020年 | 76篇 |
2019年 | 88篇 |
2018年 | 77篇 |
2017年 | 106篇 |
2016年 | 108篇 |
2015年 | 144篇 |
2014年 | 218篇 |
2013年 | 266篇 |
2012年 | 198篇 |
2011年 | 213篇 |
2010年 | 193篇 |
2009年 | 167篇 |
2008年 | 166篇 |
2007年 | 127篇 |
2006年 | 151篇 |
2005年 | 102篇 |
2004年 | 89篇 |
2003年 | 79篇 |
2002年 | 85篇 |
2001年 | 114篇 |
2000年 | 74篇 |
1999年 | 72篇 |
1998年 | 72篇 |
1997年 | 51篇 |
1996年 | 40篇 |
1995年 | 36篇 |
1994年 | 31篇 |
1993年 | 21篇 |
1992年 | 18篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有3481条查询结果,搜索用时 15 毫秒
531.
为观察新生鼠全氟辛烷磺酸(PFOS)低剂量慢暴露对其成年后神经行为和海马组织影响,选取出生后5-7 d雄性SD幼鼠80只,按体重随机分为4组,分别为对照组(Con)、低剂量组(P5)、中剂量组(P10)、高剂量组(P20),每组各20只。从PND7开始染毒,共染毒12周,动态记录体重,并进行水迷宫、旷场实验、滚轮实验观察神经行为变化,同时取材进行HE染色,观察海马形态学改变。结果显示与Con组比较,P20组染毒8 d后出现体重增长减缓(P0.05),4周时P10和P20组死亡率明显升高;并且P10、P20组在4周,P5组在8周时,水迷宫实验逃逸潜伏期延长,目标象限停留时间缩短;P10、P20组大鼠在4周,P5组在8周时,旷场实验中央格停留时间延长,站立次数减少,行走总距离缩短;滚轮试验中,对照组和P5组肢体运动协调能力无显著性差异。P5组在染毒12周时出现海马神经元排列紊乱,胞核固缩及胞体胀大,CA1区细胞和齿状回闩区神经前体细胞数量明显少于Con组(P0.01)。上述结果表明,大鼠幼年PFOS低剂量慢暴露可损害其成年后空间学习记忆及自主探究能力,这种损害可能与海马神经元发生不足有关 相似文献
532.
Yan GUO Chuanfu WU Qunhui WANG Min YANG Qiqi HUANG Markus MAGEP Tianlong ZHENG 《Frontiers of Environmental Science & Engineering》2016,10(4):6
The use of PLA/starch blends for nitrogen removal was achieved.
The influence of different operating parameters on responses was verified using RSM.
The conditions for desired responses were successfully optimized simultaneously.
Blends material may have a promising application prospect in the future.
Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid (PLA)/starch blends as carbon source and carrier for functional bacteria. The exclusive and interactive influences of operating parameters (i.e., temperature, pH, stirring rate, and PLA-to-starch ratio (PLA proportion)) on nitrification (Y1), denitrification (Y2), and COD release rates (Y3) were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous nitrification and denitrification. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows: for Y1, pH>stirring rate>PLA proportion>temperature; for Y2, pH>PLA proportion>temperature>stirring rate; and for Y3, stirring rate>pH>PLA proportion>temperature. In this study, the following optimum conditions were observed: temperature, 32.0°C; pH 7.7; stirring rate, 200.0 r·min-1; and PLA proportion, 0.4. Under these conditions, Y1, Y2, and Y3 were 134.0 μg-N·g-blend-1·h-1, 160.9 μg-N·g-blend-1·h-1, and 7.6 × 103 μg-O·g-blend-1·h-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal. 相似文献
533.
2013年4月20日四川芦山7.0级地震后,四川省宝兴县冷木沟沟道内新增大量崩塌、滑坡物源,在强降雨的诱发下,极易发生泥石流灾害,且沟口直面县城,直接威胁着整个县城的生命、财产安全。利用SCS水文模型,根据冷木沟流域的地貌特征将其划分成17个子流域,在子流域不同的土地利用数据及水文土壤条件下进行产流、汇流计算,最后通过叠加得到冷木沟流域出口断面的汇流过程;对2012年8月18日发生的泥石流汇流过程进行探讨预测,结果显示,本次泥石流的洪峰流量为278m3/s,泥石流总量为20.2×104m3,计算得到的泥石流总量与实际调查结果的相对误差为7.8%;用同一方法预测2013年5月23日冷木沟支沟黑沟的泥石流汇流过程,计算的洪峰流量为38.2 m3/s,与实际监测值的相对误差为4.2%。说明此模型对于冷木沟流域具有适用性,且效果较好,可用于宝兴县冷木沟泥石流的流量预测及泥石流灾害规模预测,将对宝兴县的泥石流防灾减灾工作提供科学指导。 相似文献
534.
利用X射线吸收精细结构谱(XAFS)对老化过程中土壤中铜的分子形态进行初步表征。以硫酸铜、氧化铜和硫化铜的X射线吸收扩展边结构(EXAFS)谱为参比,对土壤样品中Cu的EXAFS谱进行拟合,得到不同老化阶段与参比物质相对应的结合态Cu的百分含量,并与连续提取法表征进行比较。XAFS分析结果表明,老化阶段土壤样品中铜的主要结合形态是CuSO_4,同时还有部分CuS,基本不含有CuO。随着时间的推移,土壤中CuSO_4百分含量呈现出下降的趋势,CuS百分含量呈现出上升的趋势。这与连续提取法研究结果中其可交换态的百分比下降,残渣态上升的趋势相似。 相似文献
535.
Zhuoying WU Qing WANG Feng GUO Shenghua ZHANG Qipei JIANG Xin YU 《Frontiers of Environmental Science & Engineering》2014,8(2):205-214
Often as a result ofbiofilm formation, drinking water distribution systems (DWDS) are regularly faced with the problem of microbial contamination. Quorum sensing (QS) systems play a marked role in the regulation of microbial biofilm formation; thus, inhibition of QS systems may provide a promising approach to biofilm formation control in DWDS. In the present study, 22 bacterial strains were isolated from drinking water-related environments. The following properties of the strains were investigated: bacterial biofilm formation capacity, QS signal molecule N-acyl-L-homoserine lactones (AHLs) production ability, and responses to AHLs and AHL analogs, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)- furanone (MX) and 2(5H)-furanone. Four AHLs were added to developed biofilms at dosages ranging from 0.1 nmol.L J to 100nmol.L1. As a result, the biofilm growth of more than 1/4 of the isolates, which included AHL producers and non-producers, were significantly promoted. Further, the biofilm biomasses were closely associated with respective AHLs concentrations. These results provided evidence to support the idea that AHLs play a definitive role in biofilm formation in many of the studied bacteria. Meanwhile, two AHLs analogs demon- strated unexpectedly minimal negative effects on biofilm formation. This suggested that, in order to find an applicable QS inhibition approach for biofilm control in DWDS, the testing and analysis of more analogs is needed. 相似文献
536.
Jiaxing Guo Huan Liu Yang Jiang Dongquan He Qidong Wang Fei Meng Kebin He 《Frontiers of Environmental Science & Engineering》2014,8(1):79-88
To understand the household C02 emission level in China, as well as how much the neighborhoods' socio-economic or design factors could influence the CO2 emission, 23 neighborhoods in Jinan were investigated in 2009 and 2010. These neighborhoods fall into four different types: superblock, enclave, grid and traditional. The household CO2 emission includes sources of both in- home energy use and passenger transportation. The average CO2 emission per household is 7.66 t.a^-1, including 6.87 t in-home operational emission and 792 kg transportation emission. The household CO2 emission by neighborhood categories is 10.97, 5.65, 6.49, 5.40 t-household-1. a-1 for superblock, enclave, grid and tradi- tional respectively. Superblock has the highest average emission and also the highest percent (more than 25%) of transportation emission among four different types of neighborhoods. The residential CO2 emission of superb- lock neighborhoods in Jinan has already reached the level in developed countries nearly ten years ago. It is predictable that more superblock neighborhoods would be built in China with the fast urbanization. How to avoid the rapid household CO2 emission growth in the future would be a systematic issue. The study also found that in addition to income and apartment area, household density, land use mix and accessibility to public transportation are three primary factors which have significant impacts on CO2 emission. High density, mixed land use and convenient accessibility to public transportation tend to reduce household CO2 emission. 相似文献
537.
538.
山阴水砷中毒区地下水砷的富集因素分析 总被引:27,自引:5,他引:22
通过对山阴地区66个地下水样中常量元素、微量元素及有机物分析,研究了山阴高砷地下水的水化学特性并在此基础上,结合该地区含水层沉积物矿物分析,探讨了地下水中砷富集的影响因素.结果表明,山阴地下水平均pH为8.09,磷酸根含量为0.71mg/L,溶解性有机物含量为5.14 mg/L,以及地下水处于还原环境.高pH值、高磷酸根含量及还原环境不利于含水介质对以阴离子形式存在的砷的吸附,高溶解性有机物含量则增加了砷的活性这些因素促使了含水介质中砷的解吸和迁移. 相似文献
539.
Yao CHEN Jinhui LI Huabo DUAN Zhishi WANG 《Frontiers of Environmental Science & Engineering》2011,5(2):167-174
Mechanical waste-processing methods, which combine crushing and separation processes for the recovery of valuable materials, have been widely applied in waste printed wiring board (PWB) treatment. However, both the high impact toughness and the tensile and flexural strengths of whole PWB with a laminated structure result in great energy consumption and severe abrasion of the cutters during multi-level crushing. In addition, the high temperatures occurring in continual crushing probably cause the decomposition of the polymer matrix. A thermal-crack method using residual steam as the heating medium has been developed to pre-treat waste PWBs. This treatment reduces the mechanical strength in order to improve the recovery rate of valuable materials in subsequent mechanical recycling. The changes of the PWBs’ macro-mechanical properties were studied to evaluate thermal expansion impacts associated with changes in temperature, and the dynamic dislocation micro-structures were observed to identify the fracture mechanism. The results showed that thermal cracking with steam at the temperature of 500 K can effectively attenuate the mechanical properties of waste PWBs, by reducing the impact, tensile and flexural strengths respectively, by 59.2%, 49.3% and 51.4%, compared to untreated PWB. Thermal expansion can also facilitate the separation of copper from glass fiber by reducing peel resistance by 95.4% at 500 K. It was revealed that the flexural fracture was a transverse cracking caused by concentrated stress when the heating temperature was less than 500 K, and shifted to a vertical cracking after exceeding 500 K. 相似文献
540.