首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1209篇
  免费   84篇
  国内免费   376篇
安全科学   89篇
废物处理   70篇
环保管理   88篇
综合类   689篇
基础理论   183篇
环境理论   1篇
污染及防治   405篇
评价与监测   54篇
社会与环境   52篇
灾害及防治   38篇
  2023年   26篇
  2022年   85篇
  2021年   75篇
  2020年   55篇
  2019年   38篇
  2018年   42篇
  2017年   68篇
  2016年   53篇
  2015年   68篇
  2014年   104篇
  2013年   138篇
  2012年   108篇
  2011年   105篇
  2010年   87篇
  2009年   63篇
  2008年   88篇
  2007年   61篇
  2006年   57篇
  2005年   34篇
  2004年   30篇
  2003年   32篇
  2002年   32篇
  2001年   30篇
  2000年   32篇
  1999年   28篇
  1998年   21篇
  1997年   24篇
  1996年   17篇
  1995年   16篇
  1994年   13篇
  1993年   19篇
  1992年   5篇
  1991年   4篇
  1990年   4篇
  1989年   2篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1973年   1篇
排序方式: 共有1669条查询结果,搜索用时 15 毫秒
51.
A systematic understanding of dynamic animal extinction trajectories for different regions in a nation like China is critically important to developing practical conservation strategies. We explored historical and contemporary changes in terrestrial mammalian diversity to determine how diversity in each of the 5 regions in China has changed over time and to examine the conservation potential of these regions. We used records from databases on Pleistocene mammalian fossils and historical distribution records (1175–2020) for Primates (as a case study) to reconstruct evolutionary and historical distribution trajectories of the 11 orders of terrestrial mammals and to predict their prospective survival based on the national conservation strategy applied. The results indicated that since the Pleistocene, 4–5 mammalian orders have been lost in the northeast, 3 in central China, 2 along the coast, and 1 in the northwest. In the southwest, all 11 orders were maintained. Contemporarily, the coast and southwest had the highest and second-highest species densities. The southwest region and southeastern sections of the northwest region were the most historically and contemporarily diverse areas, which suggests that they should be the first priority for protected area (PA) designation. The central and coastal areas should be secondarily prioritized. In these 2 regions, conservation should focus on human coexistence with nature. Less attention should be paid to the PA in the northeast and western northwest because in these areas ecosystems are depauperate and the climate is harsh. Conservation in these areas should focus principally on avoiding further human encroachment on natural areas. Article impact statement: Historical and contemporary patterns of extinction can be a basis for mammalian conservation strategies.  相似文献   
52.
Environmental Science and Pollution Research - Drinking water containing environmental endocrine disruptor compounds (EDCs) endangers human health, and researching the purification process of...  相似文献   
53.
Nonferrous metal is an important basis material for the development of the national economy, and its consumption directly affects economic development. It has great significance in the effective utilization of nonferrous metals, development of an environment-friendly society, and investigation of the decoupling of nonferrous metal consumption and GDP growth. The decoupling indicators for nonferrous metal consumption and GDP growth (D r) in China from 1995 to 2010 were calculated in this study, and the results were analyzed. A productive model based on BP neural network was established. Then, the decoupling indicators for nonferrous metal consumption and GDP growth in China for the period of 2011–2020 were predicted. For the period of 1995–2010, the annual average decoupling indicators were <1 for copper, aluminum, zinc, lead, and nickel, except for tin, which was 0.21. The analysis showed that the decoupling of nonferrous metal consumption and GDP growth is in a less optimistic situation to copper, aluminum, zinc, lead, and nickel in China from 1995 to 2010. The annual average decoupling indicator for tin was 0.21, which indicates relative decoupling. For the period of 2011–2020, the predicted decoupling indicators for copper, aluminum, zinc, lead, nickel, and tin were between 0 and 1. This finding indicates the implementation of relative decoupling. However, the total consumption of nonferrous metals did not decouple from GDP growth.  相似文献   
54.
The aim of this study was to investigate the pollution characteristics of typical veterinary antibiotics in manure and soil of livestock farms in Jiangsu province. This investigation employed solid-phase extraction (SPE) coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A total of 53 manure and 50 amended soil samples from 16 livestock farms in Jiangsu province were collected for analysis. In the manure samples, the highest detected frequencies and concentrations were those of tetracyclines (TCs, 54.1 ± 5775.6 μgkg?1), followed by fluoroquinolones (FQs, 8.4 ± 435.6 μgkg?1), sulphonamides (SAs, 3.2 ± 5.2 μgkg?1) and macrolides (MACs, 0.4 ± 110.5 μgkg?1). Statistical analysis was used to illuminate the pollution characteristics of 23 veterinary antibiotics for various animal types and different regions in Jiangsu province. The results showed that the pollution level in cow manure was relatively lower compared with pig and chicken manure due to the relative restriction of medication. Furthermore, contamination was serious in amended soil from chicken farms. The pollution level in manure among different regions was higher to the south and north compared with the centre of the region. The same outcome was found for soil. Antibiotic residues in organic fertilizer were also investigated in this study. We found that although the detected concentration was lower in organic fertilizer than in fresh manure, detection frequencies (10–90%) were high, especially for roxithromycin (90%) in MACs (30–90%). This finding suggests attention should be paid to the pollution levels in organic fertilizer. This study is the first extensive investigation of the occurrence and distribution of many kinds of typical veterinary antibiotics in manure and soil from livestock farms of Jiangsu province. This investigation systematically assesses veterinary antibiotics usage and related emissions in southeast China.  相似文献   
55.
Laboratory batch and column experiments were conducted to investigate the immobilization of phosphorus (P) in soils using synthetic magnetite nanoparticles stabilized with sodium carboxymethyl cellulose (CMC-NP). Although CMC-stabilized magnetite particles were at the nanoscale, phosphorus removal by the nanoparticles was less than that of microparticles (MP) without the stabilizer due to the reduced P reactivity caused by the coating. The P reactivity of CMC-NP was effectively recovered when cellulase was added to degrade the coating. For subsurface non-point P pollution control for a water pond, it is possible to inject CMC-NP to form an enclosed protection wall in the surrounding soils. Non-stabilized “nanomagnetite” could not pass through the soil column under gravity because it quickly agglomerated into microparticles. The immobilized P was 30% in the control soil column, 33% when treated by non-stabilized MP, 45% when treated by CMC-NP, and 73% when treated by both CMC-NP and cellulase.  相似文献   
56.
太阳光Fenton法处理垃圾渗滤液中有机污染物   总被引:7,自引:1,他引:6  
研究利用太阳光Fenton法处理垃圾渗滤液。根据太阳光辐射强度随时间的变化规律,选择重庆7、8月份的晴天,在中午12:00到下午14:00时进行试验,研究太阳光辐射时间、pH值、Fenton试剂用量对垃圾渗滤液COD去除率的影响。研究结果表明:太阳光Fenton法对垃圾渗滤液的COD有较好的去除效果,COD去除率达86.2%。太阳光Fenton法处理垃圾渗滤液的优化条件是:日光辐射时间为120 min,pH值为2.5,Fe2+浓度为5 mmol/L,H2O2浓度为570 mmol/L。同时,论文还对太阳光Fenton法处理垃圾渗滤液的动力学进行分析。研究结果显示:太阳光Fenton法处理垃圾渗滤液,其表观动力学方程为-dC/dt=2.6×10-8×P1.92×F1.79×E1.67。  相似文献   
57.
Environmental Science and Pollution Research - In 2017, the 19th National Congress of the Communist Party of China put forward the concept of high-quality economic development, indicating that the...  相似文献   
58.
Environmental Science and Pollution Research - In this work, various photocatalysts were synthesized with an impregnation-precipitation process to in situ decorate Ag-based nanoparticles (NPs,...  相似文献   
59.
The relationship between the fine particles emitted after desulfurization and gypsum crystals in the desulfurization slurry was investigated, and the crystallization characteristics varying with the operation parameters and compositions of the desulfurization slurry were discussed. The results showed that the fine particles generated during the desulfurization process were closely related to the crystal characteristics in the desulfurization slurry by comparison of their morphology and elements. With the higher proportion of fine crystals in the desulfurization slurry, the number concentration of fine particles after desulfurization was increased and their particle sizes were smaller, indicating that the optimization of gypsum crystallization was beneficial for the reduction of the fine particle emission. The lower pH value and an optimal temperature of the desulfurization slurry were beneficial to restrain the generation of fine crystals in the desulfurization slurry. In addition, the higher concentrations of the Fe3 + ions and the F ions in the desulfurization slurry both promoted the generation of fine crystals with corresponding change of the morphology and the effect of the Fe3 + ions was more obvious. With the application of the desulfurization synergist additive, it was beneficial for the inhibition of fine crystals while the thinner crystals were generated.  相似文献   
60.
利用餐厨垃圾湿热处理脱出液制备液态菌肥研究   总被引:1,自引:1,他引:0       下载免费PDF全文
以餐厨垃圾湿热处理脱出液为发酵培养基,选用圆褐固氮菌(Azotobacter chroococcum)作为实验菌种制作固氮液态菌肥。测定了圆褐固氮菌的主要生理特性,将其接种于餐厨湿热处理脱出液中进行培养,确定最佳发酵时间,并分别测定发酵的最佳初始p H值、接种量、培养温度、摇床转速、装液量、脱出液与水的混合比例。结果表明:圆褐固氮菌在餐厨湿热处理脱出液中最佳发酵时间为36 h,发酵最佳初始p H值、接种量、培养温度、摇床转速、装液量、脱出液与水的混合比例依次为7.5、1%、30℃、150 r/min、50 m L(250 m L锥形瓶)、1∶1。圆褐固氮菌在餐厨垃圾湿热处理脱出液中进行培养后,可达到液态菌肥的活菌数标准。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号