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   1572篇
  免费   5篇
  国内免费   7篇
安全科学   10篇
废物处理   71篇
环保管理   80篇
综合类   522篇
基础理论   362篇
污染及防治   364篇
评价与监测   97篇
社会与环境   68篇
灾害及防治   10篇
  2017年   15篇
  2016年   20篇
  2014年   21篇
  2013年   69篇
  2012年   22篇
  2011年   45篇
  2010年   44篇
  2009年   48篇
  2008年   66篇
  2007年   51篇
  2006年   46篇
  2005年   45篇
  2004年   41篇
  2003年   37篇
  2002年   48篇
  2001年   59篇
  2000年   54篇
  1999年   34篇
  1998年   20篇
  1997年   30篇
  1996年   28篇
  1995年   30篇
  1994年   28篇
  1993年   26篇
  1992年   19篇
  1991年   36篇
  1990年   50篇
  1989年   23篇
  1988年   27篇
  1987年   20篇
  1985年   21篇
  1984年   21篇
  1983年   16篇
  1982年   30篇
  1979年   18篇
  1978年   13篇
  1977年   15篇
  1976年   13篇
  1974年   17篇
  1972年   17篇
  1971年   12篇
  1969年   11篇
  1968年   12篇
  1967年   23篇
  1966年   19篇
  1965年   13篇
  1964年   12篇
  1962年   13篇
  1958年   14篇
  1957年   12篇
排序方式: 共有1584条查询结果,搜索用时 15 毫秒
901.
The platinum group metals (PGM) Pt and Rh are emitted into the environment mainly by catalytic exhaust gas converters of cars and by effluents of hospitals, which use Pt based anti-cancer drugs. However, there is still a lack of information on the availability of these precious metals to the biosphere. As PGM accumulate in sediments of aquatic ecosystems we focused our study on the uptake of the noble metals by European eels, Anguilla anguilla. Therefore, eels were exposed in tap water and humic water containing Pt(4+) and Rh(3+) at a concentration of 170 and 260 microg/l, respectively. After an exposure period of 6 weeks the mean Pt levels in bile, liver, kidney and intestine of the exposed eels ranged between 68 ng/g and 840 ng/g and the mean Rh levels between 35 ng/g and 155 ng/g whereas the PGM levels of the unexposed controls were below the detection limit of 50 ng/g for Pt and 5 ng/g for Rh. Rh was also taken up by gill and spleen. No PGM uptake was found for muscle and blood. The pattern of metal distribution within the eel differed between Pt and Rh and was dependent on the water type. Due to their accumulation capacity for PGM eels are suitable as accumulation indicators to detect PGM pollution in aquatic ecosystems.  相似文献   
902.
Burreau S  Broman D  Orn U 《Chemosphere》2000,40(9-11):977-985
In the present study, the tissue distribution of [14C]-labelled 2,2',4,4'-tetrabrominated diphenyl ether (PBDE 47) and its possible metabolites was investigated after dietary exposure in pike (Esox lucius) using whole-body autoradiography. The study is a time series with pike examined 9, 18, 36 and 65 days after exposure. PBDE 47 was efficiently absorbed from the food (>90%) and radioactivity remained in the body in considerable amounts even after the longest period examined. The results indicate that PBDE 47 is not rapidly metabolised to hydrophilic, but possible to hydrophobic metabolites and that PBDE 47 and possible hydrophobic metabolites are accumulated in the lipid rich tissues of the pike. Melanin binding of PBDE 47 and possible metabolite(s) is suggested. The levels of PBDE 47 and/or metabolite(s) declines with time in most tissues except for the most lipid rich, where no decline in radioactivity is observed even after the longest period studied. Signs of irreversible incorporation of PBDE 47-derived radioactivity were detected but considered as too uncertain to conclude that covalent binding of PBDE 47-metabolites to macromolecules occurs.  相似文献   
903.
In this study it was evaluated whether the ECOPATH with ECOSIM software could be used as a platform to facilitate the construction of models and study of transport and accumulation of radionuclides in aquatic food webs. The evaluation was based upon a food web model of carbon (C) and carbon-14 ((14)C) flow for a coastal area in the Baltic Sea, the ECOPATH, the ECOSIM and the ECOTRACE models. The original carbon flows and assumptions were easily incorporated into the ECOPATH and ECOSIM modelling environment. The new model was also well suited to drive a (14)C flow model (ECOTRACE) for each of the organisms included. ECOTRACE estimated steady-state concentrations of (14)C that were between 73 and 142% of the original flows. The results clearly show that there is great potential for a successful development of this approach for integrating scientific knowledge about food webs and radioecological models for aquatic systems.  相似文献   
904.
Environmental Science and Pollution Research - This study evaluated the reutilization of waste materials (scrap tires, sewage sludge, and wood chips) to remove volatile organic compounds (VOCs)...  相似文献   
905.
An attempt was made to investigate the relationship between raw coal characteristics and effluent quality in two coking coal washeries of Central Coalfields Limited, Kedla and Rajrappa in Jharkhand State, India. Coal samples-raw coal feed, washed fine clean coal, washed coarse clean coal, middlings and rejects were collected. Similarly, raw water (intake to washery) and effluent samples generated in the washeries, namely, fine coal jig under water, coarse coal jig under water and slurry pond water were also collected over a period of 6 months. Parameters outlined in Ministry of Environment and Forest (MoEF) Schedule VI Indian standards were determined, both in coal samples and water/washery effluent samples. Apart from the parameters listed in the standard, sodium, potassium, calcium, magnesium, sulphate and chloride found to be present in coal were also determined in coal and water samples. The processing results essentially in production of huge quantities of suspended material, which is beyond the stipulated limit of 100mg/l as specified in the Standard. Lowering of pH was observed in both the washeries. The trace/heavy elements were found to be concentrated in the heavier fractions in rejects produced from the washery. The concentrations of major elements in coal-Na, K, Ca, Mg, and minor elements in coal-Mn; F, SO4 and Cl were found to be higher in process water than in raw water indicating that these elements are transferred from coal to the water in washeries. However, only in the case of Mn, the stipulated limit of the effluent standard was exceeded. Trace elements like As, Se, Hg, Cd, though found to be present in coal, were absent in the process water indicating that these elements are not released by coal during washing.  相似文献   
906.
907.
908.
909.
The feasibility of utilizing non edible rice (broken rice) for production of fine materials such as poly(3-hydroxybutyrate) (PHB) was considered as one of the alternative ways of keeping the environment clean for sustainable development. Thus, production of PHB from broken rice by simultaneous saccharification and fermentation (SSF) was investigated. During the SSF process, the rice (15% w/v) material was hydrolyzed to glucose, which was utilized by Cupriavidus necator for growth and production of PHB. The PHB content reached 38% at 58 h fermentation. The PHB had weight average molar mass (Mw) and polydipersity index of 3.82 × 105 (g/mol) and 4.15, respectively. Differential calorimetric scan of the PHB showed a melting temperature (Tm) of 176 °C. Given that the PHB was a homopolymer (which consisted of (R)-3-hydroxybutyric acid monomers), it was thought that broken rice could be a raw material for production of both PHB and (R)-3-hydroxybutyric acid. This SSF process would not only help in the utilization of broken rice or non edible rice, but would also serve as a model for utilization of other raw materials that contain starch for production of PHB.  相似文献   
910.
Serial samples with a multiple corer were taken in order to understand the small-scale aggregation patterns in the nematode community. A total of 77 species was found in the sample. Fifteen dominant nematode species were examined by means of a dispersion analysis. Only one species (Metachromadora scotlandica) may be considered randomly distributed. A variogram analysis gave no proof of aggregation in that species, but all the other (aggregated) species displayed different spatial patterns: (1) a maximum/aggregation at the sample's margin, (2) two maxima/aggregations in the centre of the sample, (3) aggregation of individuals distributed at random over the entire sample (Metalinhomoeus typicus) and (4) aggregation of individuals distributed at random only in the centre of the sample (Paralinhomoeus ilenensis). These results allow the prognosis that distribution patterns are repetitive in five species (Microlaimus conothelis, M. marinus, Odontophora rectangula, Oncholaimellus calvadosicus, Viscosia rustica). Finally, by means of MDS-ordination (based on cosine similarity) two nematode associations were distinguished: one group represented by diatom-feeders (sensu lato), the other one comprised of DOM-users (sensu lato). Received: 13 May 1998 / Accepted: 15 January 1999  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