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   433篇
  免费   34篇
  国内免费   187篇
安全科学   12篇
废物处理   8篇
环保管理   57篇
综合类   302篇
基础理论   137篇
污染及防治   102篇
评价与监测   14篇
社会与环境   16篇
灾害及防治   6篇
  2024年   1篇
  2023年   9篇
  2022年   13篇
  2021年   15篇
  2020年   9篇
  2019年   9篇
  2018年   17篇
  2017年   15篇
  2016年   22篇
  2015年   15篇
  2014年   14篇
  2013年   66篇
  2012年   46篇
  2011年   40篇
  2010年   30篇
  2009年   38篇
  2008年   41篇
  2007年   27篇
  2006年   34篇
  2005年   32篇
  2004年   31篇
  2003年   17篇
  2002年   12篇
  2001年   17篇
  2000年   17篇
  1999年   10篇
  1998年   11篇
  1997年   11篇
  1996年   7篇
  1995年   3篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1991年   2篇
  1989年   4篇
  1987年   2篇
  1983年   2篇
  1982年   3篇
  1978年   1篇
排序方式: 共有654条查询结果,搜索用时 250 毫秒
291.
分别制备了花状Bi2MoO6和片状Ni2P,采用研磨、水热及超声的方式将两种材料复合,考察了负载方式、负载率和溶液pH值对其可见光下降解亚甲基蓝(MB)的影响;利用XRD、XPS、FTIR、SEM、PL和UV-Vis等测试手段表征了样品的微观结构、形貌和光学性质;研究表明Ni2P作为助催化剂,可加速电子空穴对分离,显著提高Bi2MoO6的光催化活性,其中当Ni2P负载率为4%时,TOC去除率为64.28%,降解速率为纯Bi2MoO6的2倍,且将Ni2P/Bi2MoO6复合催化剂循环利用3次后,同实验条件下降解率为94%,证明复合催化剂稳定性好.  相似文献   
292.
NO2是重要的痕量气体,对其监测有助于大气污染治理。本文基于Sentinel-5P大气污染监测卫星提供的对流层NO2浓度数据和总NO2浓度数据,借助谷歌地球引擎(google earth engine,GEE)分析了2018~2021年间中国大气NO2浓度时空变化特征,使用OLS模型揭示了中国地区NO2浓度的主要影响因子。结果表明:我国对流层NO2浓度空间分布呈现东高西低的总体格局,东中部城市群对流层NO2柱浓度水平明显呈现冬高夏低、春秋过渡的季节特征,西部大部分城市的四季变化不明显。北京、深圳、上海3所城市NO2柱浓度分布呈现出较为显著的圈层结构。OLS模型结果表明,中国地区NO2浓度变化受到社会经济和自然因素的共同影响,其中城市化程度是影响NO2排放的重要因子。  相似文献   
293.
采用磷酸氢二铵为活化剂和N、P源,竹屑为碳源,通过一步热解法制备N、P共掺杂活性炭,并将其用于高效去除水溶液中的La3+.分析了活化温度和pH值对La3+吸附性能的影响,并通过TG-IR、SEM-EDX、孔隙结构、XPS以及亲水性等探究其活化和吸附机制.结果表明,磷酸氢二铵在高温下容易分解产生氨气和磷酸,对物料起到活化作用,促进活性炭比表面积和孔隙容积的提高;作为N、P源,磷酸氢二铵的添加成功实现了活性炭的N、P共掺杂,而含N、P官能团的引入是提升La3+吸附量的关键.其中,石墨氮可以提供La3+—π键间的相互作用,C—P=O和C/P—O—P可通过络合作用和静电作用为吸附La3+提供活性位点.La3+在N、P共掺杂活性炭上的吸附是吸热和自发的,吸附过程符合Langmuir等温式和二级动力学模型.在活化温度为900℃,pH=6的工艺条件下,N、P共掺杂活性炭的吸附量高达55.18 mg·g-1,比未掺杂样品高2.53倍,并且其在La3+/Na+和La3+/Ca2+共存体系中对La3+的吸附选择性分别达到93.49%和82.49%,经过5次连续的吸附-解吸循环实验去除效率仍高于54%.  相似文献   
294.
This paper aims to provide empirical research to identify the linkages between final demand–total output, final demand–total supply, value-added ratios and prices, and also to analyze total factor productivity growth using input–output framework for 25 sectors. Studying the input–output tables for 2001 and 2006, the research estimates impact and response multipliers of non-oil sectors, as well as non-oil trading sectors. The results are important from the view of development of non-oil trading sectors and diversification of the economy in order to avoid the “resource curse”.  相似文献   
295.
代谢组学作为系统生物学的一部分,通过考察机体受刺激后体液或组织中内源性代谢物的动态变化规律,并结合生物信息统计方法,可系统全面地揭示内因和外因作用于机体的毒性效应和机制。代谢组学技术具有快速、灵敏度高、选择性强的特点,逐渐在低剂量环境污染物长期暴露的毒性效应评估方面发挥出优势。本文综述了代谢组学技术的主要研究手段,在毒理学研究中的发展历程和优点,以及在环境毒理学研究中的应用及前景展望。重点讨论了代谢组学技术在重金属和持久性有机污染物(POPs)毒性评估以及环境胁迫耐受性评价中的应用。  相似文献   
296.
Seasonal variations in dissolved and particulate P forms were assessed in the estuarine system of Chalakudy River, Kerala, South India – a tropical river having substantial relics of riparian vegetation. The contribution of the reactive P form extended to 84–96% compared with the residual fraction. Geographical and human activities have had effects on the phosphorus-loading capacity at various locations, which reveal pronounced variability in P distribution. Not all forms of phosphate in suspended particulate matter are likely to be released, and thus the nature of the P forms within the stock is a sensitive factor that can be utilised. Ca-bound P in suspensates increases to a highly significant level in the estuarine area, whereas Fe/Al-bound P predominates at the riverine and catchment areas during both the monsoon and non-monsoon seasons. Thus, calcium compounds determine the availability of P in the alkaline estuarine environment, whereas in the riverine environment, Al and Fe control P solubility. The comparatively low P load in upstream waters indicates that, under ambient situations, vegetative riparian zones can be very important P filters.  相似文献   
297.
Sensory neurons originating in nodose and jugular ganglia that innervate airway epithelium (airway neurons) play a role in inflammation observed following exposure to inhaled environmental irritants such as ozone (O3). Airway neurons can mediate airway inflammation through the release of the neuropeptide substance P (SP). While susceptibility to airway irritants is increased in early life, the developmental dynamics of afferent airway neurons are not well characterized. The hypothesis of this study was that airway neuron number might increase with increasing age, and that an acute, early postnatal O3 exposure might increase both the number of sensory airway neurons as well as the number SP-containing airway neurons. Studies using Fischer 344 rat pups were conducted to determine if age or acute O3 exposure might alter airway neuron number. Airway neurons in nodose and jugular ganglia were retrogradely labeled, removed, dissociated, and counted by means of a novel technique employing flow cytometry. In Study 1, neuron counts were conducted on postnatal days (PD) 6, 10, 15, 21, and 28. Numbers of total and airway neurons increased significantly between PD6 and PD10, then generally stabilized. In Study 2, animals were exposed to O3 (2?ppm) or filtered air (FA) on PD5 and neurons were counted on PD10, 15, 21, and 28. O3-exposed animals displayed significantly less total neurons on PD21 than FA controls. This study shows that age-related changes in neuron number occur, and that an acute, early postnatal O3 exposure significantly alters sensory neuron development.  相似文献   
298.
通过对连云港市农业非点源氮磷污染对水环境影响的研究,掌握了连云港市农业非点源氮磷污染情况及氮磷在土壤中的转化机制,监测分析了水环境氮磷污染现状及氮磷对水环境的影响途径,提出了控制农业非点源氮磷对水体环境污染的措施。  相似文献   
299.
Benzo[a]pyrene (B[a]P) is accumulating in soils in a low-dose cumulative manner. The objectives of this study were to investigate the effects of B[a]P on the extractable and available fractions of B[a]P and on soil enzymatic activity using multiple-time superimposed and one-time contamination approaches. Results showed that the contents of B[a]P rapidly decreased in the first 14?d and later decreased slowly from 14 to 56?d in both one-time and multiple-time contamination tests. The contents of B[a]P in the multiple-time contamination test were lower than those in the one-time test. Soil urease, sucrase and dehydrogenase activities were rapidly inhibited in the early stage (14?d) and stimulated during the rest of the incubation, and soil dehydrogenase activity was more sensitive to B[a]P contamination than the other enzymes. High concentrations of B[a]P in soil led to greater inhibition of enzymatic activity than that at low concentrations in the early period of culture. Soil enzyme activities were weakly inhibited in multiple-time compared with in one-time contamination tests and were lower in the subsurface layer than in the surface layer. Our results revealed that the multiple-time superimposed approach might be better than one-time contamination for evaluating B[a]P risk in soil.  相似文献   
300.
Energy efficiency plays an important role in reducing the carbon externality from buildings, but economic analyses of more efficient, green building have thus far ignored input costs. This paper finds that the average marginal cost of green-labeled construction projects is smaller than the value premiums documented in the literature. However, design fees, representing just a fraction of development costs but paid largely up-front, are significantly higher for green construction projects. These projects also take longer to complete. The results provide some insight into the market barriers and market failures that may explain the relatively slow adoption of otherwise economically rational green construction practices.  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