全文获取类型
收费全文 | 1103篇 |
免费 | 102篇 |
国内免费 | 640篇 |
专业分类
安全科学 | 67篇 |
废物处理 | 29篇 |
环保管理 | 71篇 |
综合类 | 888篇 |
基础理论 | 394篇 |
污染及防治 | 252篇 |
评价与监测 | 27篇 |
社会与环境 | 63篇 |
灾害及防治 | 54篇 |
出版年
2024年 | 5篇 |
2023年 | 20篇 |
2022年 | 42篇 |
2021年 | 55篇 |
2020年 | 46篇 |
2019年 | 65篇 |
2018年 | 60篇 |
2017年 | 58篇 |
2016年 | 69篇 |
2015年 | 80篇 |
2014年 | 76篇 |
2013年 | 167篇 |
2012年 | 107篇 |
2011年 | 129篇 |
2010年 | 85篇 |
2009年 | 95篇 |
2008年 | 58篇 |
2007年 | 98篇 |
2006年 | 94篇 |
2005年 | 73篇 |
2004年 | 66篇 |
2003年 | 47篇 |
2002年 | 32篇 |
2001年 | 34篇 |
2000年 | 27篇 |
1999年 | 27篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 17篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有1845条查询结果,搜索用时 15 毫秒
121.
The impact of sewage sludge compost on tree peony growth and soil microbiological,and biochemical properties 总被引:1,自引:0,他引:1
In order to assess the suitability of sludge compost application for tree peony (Paeonia suffruticosa)–soil ecosystems, we determined soil microbial biomass C (Cmic), basal respiration (Rmic), enzyme activities, and tree peony growth parameters at 0–75% sludge compost amendment dosage. Soil Cmic, Rmic, Cmic as a percent of soil organic C, enzyme (invertase, urease, proteinase, phosphatase, polyphenoloxidase) activities, and plant height, flower diameter, and flower numbers per plant of tree peony significantly increased after sludge compost amendment; however, with the increasing sludge compost amendment dosage, a decreasing trend above 45% sludge compost amendment became apparent although soil organic C, total Kjeldahl N, and total P always increased with the sludge compost amendment. Soil metabolic quotient first showed a decreasing trend with the increasing sludge compost application in the range of 15–45%, and then an increasing trend from compost application of 45–75%, with the minimum found at compost application of 45%. As for the diseased plants, 50% of tree peony under the treatment without sludge compost amendment suffered from yellow leaf disease of tree peony, while no any disease was observed under the treatments with sludge compost application of 30–75%, which showed sludge compost application had significant suppressive effect on the yellow leaf disease of tree peony. This result convincingly demonstrated that ?45% sludge compost application dosage can take advantage of beneficial effect on tree peony growth and tree peony–soil ecosystems. 相似文献
122.
采用批次小试实验对不同腐熟程度的蓝藻进行厌氧发酵产沼气实验研究。结果表明,新鲜蓝藻在30-35℃时腐熟7 d后,可在35℃的厌氧温度下获得最高的产气速率和246 mL/g COD的产气量,产气潜力为354 mL/g(VS)。厌氧反应15 d后,累计产气量、COD和VFA浓度趋于稳定。淀粉酶和脱氢酶的活性在厌氧反应初期受到抑制,蛋白酶活性和辅酶F420浓度在厌氧系统中逐渐增加,分别在第6天达到27.66μmol/(g VS·min)和第15天达到0.62μmol/g(VS)。15-18d是腐熟蓝藻适宜的中温厌氧发酵时间,少于以新鲜蓝藻为基质的厌氧消化时间。蓝藻腐熟过程促进了厌氧反应,腐熟7 d的蓝藻厌氧系统具有更高的微生物活性和产甲烷能力。 相似文献
123.
The influence of intact (FLT) and photomodified (phFLT) fluoranthene (0.05, 0.5 and 5 μmol l−1) and herbicide Basagran (5, 20, 35 and 50 nmol l−1) on the germination, growth of seedlings and photosynthetic processes in pea plants (Pisum sativum L., cv. Garde) was investigated. The germination was significantly inhibited already by the lowest concentration (0.05 μmol l−1) of FLT and phFLT, while Basagran caused inhibition only in higher concentrations (35 and 50 nmol l−1). The growth of roots was significantly inhibited by higher concentration 5 μmol l−1 of both FLT and phFLT and the shoot of seedlings was significantly influenced only by photomodified form. The length of root and shoot was inhibited already by concentration 5 nmol l−1 of Basagran. Organic compounds applied on chloroplasts suspension influenced primary photochemical processes of photosynthesis. In chlorophyll fluorescence parameters, the significant increase of F0 values and the decrease of FV/FM and ΦII values by application of FLT (0.5 and 5 μmol l−1) and phFLT (0.05, 0.5 and 5 μmol l−1) was recorded. The maximum capacity of PSII (FV/FM) was influenced by the highest (50 nmol l−1) and the effective quantum yield of PSII (ΦII) already by the lowest (5 nmol l−1) concentration of Basagran. Hill reaction activity decreased and was significantly inhibited by higher concentration (0.5 and 5 μmol l−1) of FLT and phFLT and already by the lowest concentration (5 nmol l−1) of Basagran. 相似文献
124.
Water produced by advanced treatment of a groundwater was evaluated to determine the amount of DBPs (Disinfection By-Products) including trihalomethanes (THMs). Both Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GS/MS) were adopted for detection and identification of DBPs such as trihalomethanes (THMs), halo-acetic acids (HAAs) and aldehydes. Two disinfection modes (ozonation followed by chlorination and chlorination alone) were compared to determine the DBPs generation. The mutagenitic acivity of ozonated water, chlorinated water after ozonation and potable water was assessed using the Ames test. Chloroform, dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were the main constituents of THMs and HAAs, respectively. THMs accounted for more than 85% of all DBPs measured, whereas haloacetic acids accounted for around 14%. Ozonation followed by chlorination proved to be better in terms of THMs and HAAs control. The combined system produced 28.3% less DBPs compared to chlorination alone. Ozonation was found capable of reducing mutagenic matter in the groundwater by 54.7%. The combined system also resulted in water with no mutagenicity. 相似文献
125.
126.
云南近期3次中强震的天文背景 总被引:2,自引:1,他引:1
分析了澄江地震至丘北地震间云南发生的3次中强震时的天体位置、地球自转与太阳活动等天文背景,分析结果表明,尽管这3次地震的震级都较小,但都发生在震中所受引潮力变化较大时刻和太阳活动局部下降时段。 相似文献
127.
刘义高 《防灾减灾工程学报》2001,21(2):11-14,22
将安徽省六安地区流动地磁测线 12个流动地磁测点的∑ |δfi|异常与安徽中西部地震活动性作对比分析 ,初步结果为 :12个流动地磁测点的∑ |δfi|值较大 (∑ |δfi|≥Fu) ,一年内安徽中西部地区的地震活动性增强 ;反之 ,则安徽中西部地区的地震活动性较弱。此方法在地震的中短期预报中有一定的实用意义。 相似文献
128.
一个新的拓扑指数用于芳烃化合物溶解度、分配系数及生物毒性的研究 总被引:19,自引:0,他引:19
在分子拓扑理论的基础上,提出了一个新的拓扑指数Yx,并用Yx研究了芳烃化合物的溶解度、分配系数及生物毒(活)性,给出了相关方程。结果表明,新方法计算方便,物理意义明确,预测值与相应的实验值较吻合。 相似文献
129.
利用IED22000A便携式微机多道能谱仪对成都市区土壤的天然放射性核素进行了直接就地测量,估算出天然环境放射性核素^238U、^232Th、^40K的比活度范围分别为10.37~77.19Bq/kg、17,85~225.74Bq/kg、284.83~892.67Bq/kg;外照射指数范围为0.16—0.8;离地面1m高的空气吸收剂量率均值为83.23nGy/h;1外照射年有效剂量当量为0.34~0.70mSv;等效镭浓度的变化范围是59.06-386.45Bq/kg,均值为164.15Bq/kg。各项指标均在容许范围之内,因而成都市属于外照射水平的安全区域,人居环境不受影响。 相似文献
130.
沉水植物和螺类是生物防治有害水华的重要手段,然而目前关于这两者对有害蓝藻的协同抑制效率和作用机制尚不清楚.本研究利用沉水植物金鱼藻与铜锈环棱螺在实验室内探究草-螺组合系统对铜绿微囊藻(Microcystis aeruginosa)生长的抑制效果.结果表明,金鱼藻组、环棱螺组及草-螺组合系统均显著降低了体系内蓝藻Chl-a浓度、总Chl-a浓度和铜绿微囊藻密度,与初始相比,蓝藻活体Chl-a浓度分别减少99.24%、100.00%和98.61%,铜绿微囊藻密度分别减少98.64%、86.44%和97.71%.草-螺共培养和金鱼藻单独培养均可以显著抑制铜绿微囊藻生长,效果相似,而环棱螺单独培养可以使蓝藻Chl-a浓度和光曲线参数值降为零,同时使得微囊藻细胞全部失活.金鱼藻与环棱螺都可以降低铜绿微囊藻光合活性,草-螺共培养系统可以最大程度降低藻类整体的生长潜能.研究发现,草-螺耦合系统对铜绿微囊藻的总体抑制效率略低于两者单独抑制效率,表明金鱼藻和环棱螺在此过程中存在微弱的拮抗作用,但由于草-螺耦合系统的抑制成效同样显著,且抑制途径更多样,同时能更好地维持水体营养盐平衡.在实践过程中建议加强沉... 相似文献