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   561篇
  免费   3篇
  国内免费   5篇
安全科学   5篇
废物处理   36篇
环保管理   58篇
综合类   43篇
基础理论   134篇
污染及防治   157篇
评价与监测   109篇
社会与环境   26篇
灾害及防治   1篇
  2023年   15篇
  2022年   48篇
  2021年   31篇
  2020年   10篇
  2019年   11篇
  2018年   18篇
  2017年   14篇
  2016年   28篇
  2015年   17篇
  2014年   27篇
  2013年   54篇
  2012年   27篇
  2011年   30篇
  2010年   35篇
  2009年   22篇
  2008年   33篇
  2007年   26篇
  2006年   20篇
  2005年   14篇
  2004年   11篇
  2003年   13篇
  2002年   15篇
  2001年   7篇
  2000年   3篇
  1999年   5篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   4篇
  1992年   4篇
  1991年   1篇
  1989年   2篇
  1984年   1篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
  1966年   1篇
  1964年   1篇
  1961年   3篇
  1960年   1篇
  1958年   1篇
  1957年   1篇
排序方式: 共有569条查询结果,搜索用时 312 毫秒
201.
202.
Environment, Development and Sustainability - Groundwater is the major primary source of drinking and irrigation water for nearly 500 million inhabitants in both rural and urban areas of the Ganga...  相似文献   
203.
A pot culture experiment was conducted to study the effect of untreated distillery effluent on yield attributes of gobi sarson (Brassica napus. L. var. Punjabi Special) at different effluent concentrations. The effluent showed unpleasant odour, acidic pH, high COD and high chlorides. Five concentrations of the distillery effluent (20, 40, 60, 80 and 100%) were used for irrigation of B. napus plants with tap water as control. Various characteristics of siliqua (number of siliqua, average siliqua length, weight of siliqua) and seeds (number of seeds, weight of hundred seeds, economic yield) were quantified to check the variations in the yield attributes of effluent irrigated test plant. Overall, 20% distillery effluent was found to be most effective for highest number and better quality of siliqua (62.0 siliqua plant-1; weight of ten siliqua 1.21 g) and seeds (836.3 seeds plant-1; weight of 100 seeds 0.39 g), and increased yield (economic yield 2.85 g plant1; stover yield 7.85 g plant1) of the test plant.  相似文献   
204.
The study has been focused on effect of untreated distillery effluent (Devans Breweries Ltd., Jammu) on germination of gobi sarson (Brassica napus. L. var. Punjabi Special). Six treatments (E0.... E100) each having three replicates were made. E0 was taken as control in which tap water was used for irrigation of the plants. For E20, E40, E60, E80 and E100, different concentrations i.e. 20, 40, 60, 80 and 100% of effluent were used for irrigation, respectively. The 100% sample of distillery effluent analyzed for various physicochemical parameters showed acidic nature (pH 4.0) and higher values of COD (2496 mg l(-1)), TDS (799.7 mg l(-1)) and chlorides (1408 mg l(-1)). The parameters e.g. percent germination, germination index, speed of germination, and peak value were highest in treatment receiving 20% effluent concentration which also showed minimum values for percent inhibition, germination period, and delay index.  相似文献   
205.
Laboratory-scale experiments were conducted to determine the effect of heavy metals viz. copper (Cu), cadmium (Cd), chromium (Cr), lead (Pb), and zinc (Zn) on the different vital tissues of earthworm Eudrillus eugeniae such as head, gizzard, clitellum, and intestine after the worms were placed in municipal solid waste (MSW) substrate spiked with heavy metals in the concentration range of 0.05 g/kg to 1.0 g/kg of the waste for Cu, Cr, PB, and Zn and 0.05 g/kg for Cd. The experiments were conducted for 100 days with periodic observations and sample collection for investigation after every 10th day. Copper and lead metals were found to cause more deleterious effect in head, gizzard, and intestine. Chromium metal caused cellular damage to the intestinal region. In comparison, cadmium metal severity was more than copper, lead, and chromium metal. Zinc metal did not show deleterious effect on tissues. In general, earthworms can be used as biomarkers in toxicity studies related to heavy metals at cellular levels.  相似文献   
206.
Water quality was determined in the different stretches of the river Sutlej (S1, S2, and S3) for a period of 1 year (November 2006 to October 2007). S1 was at Ropar Head Works, S2 at U/S of Budha Nallah at Phillaour, and S3 was D/S of Budha Nallah in district Ludhiana (Punjab). Relatively low values of TDS, turbidity, BOD, total alkalinity, total hardness, chlorides, nitrates, and phosphates were recorded at S1 and S2 as compared to S3. Heavy metals like Pb, Zn, Cr, and Ni were detected at S2 and S3. On the basis of water quality standards given by Central Pollution Control Board, the water quality was at ??A?CB?? at S1, ??B?CC?? at S2, and ??D?CE?? at S3. For the computation of water quality rating and water quality index, nine parameters were considered. The mean values of these parameters were compared with WHO, ICMR, and ISI standards. The water quality index at stations S1, S2, and S3 was 32.84, 51.01, and 132.66, respectively. This clearly indicated that the river water at station S2 and S3 was found to be unsafe for human consumption.  相似文献   
207.
208.
Differences in impacts of climate hazards across exposed units are determined by many factors including the severity of the hazard itself, the population that is exposed to the hazard and the coping capacity of the exposed units to the hazard. Coping capacity or adaptive capacity results from a combination of development status (generic capacity) and interventions pertinent to the hazard (specific capacity). This paper explores the extent to which the generic adaptive capacity may explain the variation in tropical cyclone impacts. Therefore this paper offers an empirical approach by which adaptive capacity may be measured and validated against actual outcomes. Results not only validate the role of generic adaptive capacity in explaining variations in impact but also reveal that general development indicators are not very important as far as predicting outcomes is concerned. Those indicators of development that can be linked to the impact process are significant in explaining and predicting impact. This can help identify those aspects of generic adaptive capacity which are important from the perspective of policy action for enhancing adaptive capacity to a particular climate hazard.
Anand PatwardhanEmail:
  相似文献   
209.
In the present work, microwave joining of stainless steel (SS-316) to mild steel (MS) in bulk form has been successfully carried out using a multimode applicator at 2.45 GHz and 900 W. Principles of hybrid heating were employed using a susceptor medium so as to initiate coupling of microwave with the metals. A nickel based metallic powder was used as a sandwich layer between the bulk pieces. Samples were exposed to microwave radiation in atmospheric conditions. Resulting joints were characterized using field emission scanning electron microscope (FESEM), X-ray diffractometer, microhardness tester and universal testing machine. Microstructure study showed the faying surfaces were well fused and got bonded on either side of the base material. Formation of cementite and metallic carbides were evidenced. The average observed Vickers’ microhardness of core of the joint area was observed to be 133 Hv with 0.58% porosity. The ultimate tensile strength of the joint was found to be 346.6 MPa with percentage elongation of 13.58%. Fractography reveals that the joints failed due to both shearing of the brittle carbides and oxides as well as due to plastic flow of the ductile matrix under tensile loading.  相似文献   
210.
The development of cladding through microwave radiation is recently explored and very few, initial studies were reported elsewhere. In order to explore more viability of process, (EWAC (Ni based) + 20% Cr23C6 powder) composite cladding has been developed on substrate austenitic stainless steel (SS-316). The experiments were conducted in domestic microwave oven and the clad of thickness, approximate 500 m has been developed by the exposure of microwave radiation at frequency 2.45 GHz for duration of 360 s. Typical clads cross sections of composite clads showed good metallurgical bonding with the substrate by partial dilution. The back scattered electron image of clad cross section showed the reinforced chromium carbide (Cr23C6) particles are uniformly distributed and well embedded in the Ni based matrix. The developed clad is free from visible solidification cracking and has significantly less porosity which is of the order of 0.90%. The XRD pattern of the developed clad showed the presence of FeNi3, NiSi and Cr23C6 phases. The average Vicker's microhardness of developed clad was observed as 425 ± 140 Hv.  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