全文获取类型
收费全文 | 6308篇 |
免费 | 49篇 |
国内免费 | 117篇 |
专业分类
安全科学 | 590篇 |
废物处理 | 328篇 |
环保管理 | 384篇 |
综合类 | 1422篇 |
基础理论 | 1525篇 |
环境理论 | 4篇 |
污染及防治 | 1559篇 |
评价与监测 | 241篇 |
社会与环境 | 396篇 |
灾害及防治 | 25篇 |
出版年
2023年 | 70篇 |
2022年 | 11篇 |
2021年 | 86篇 |
2020年 | 64篇 |
2019年 | 108篇 |
2018年 | 140篇 |
2017年 | 184篇 |
2016年 | 280篇 |
2015年 | 169篇 |
2014年 | 145篇 |
2013年 | 261篇 |
2012年 | 247篇 |
2011年 | 351篇 |
2010年 | 370篇 |
2009年 | 490篇 |
2008年 | 286篇 |
2007年 | 471篇 |
2006年 | 305篇 |
2005年 | 266篇 |
2004年 | 187篇 |
2003年 | 225篇 |
2002年 | 203篇 |
2001年 | 207篇 |
2000年 | 122篇 |
1999年 | 144篇 |
1998年 | 56篇 |
1997年 | 50篇 |
1996年 | 36篇 |
1995年 | 57篇 |
1994年 | 50篇 |
1993年 | 78篇 |
1992年 | 88篇 |
1991年 | 86篇 |
1990年 | 76篇 |
1989年 | 44篇 |
1988年 | 67篇 |
1987年 | 95篇 |
1986年 | 48篇 |
1985年 | 34篇 |
1984年 | 32篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 20篇 |
1979年 | 8篇 |
1978年 | 17篇 |
1977年 | 14篇 |
1976年 | 17篇 |
1974年 | 8篇 |
1973年 | 9篇 |
排序方式: 共有6474条查询结果,搜索用时 15 毫秒
11.
《Agriculture, ecosystems & environment》2006,112(2-3):153-162
Slurries are a significant source of CH4, NH3 and N2O emissions to the atmosphere. The research project aimed at quantifying CH4, NH3 and N2O emissions from liquid manure stores and after manure application under field conditions. The influence of the manure treatment options “no treatment”, “slurry separation”, “anaerobic digestion”, “slurry aeration” and “straw cover” on the emission level was investigated. Approximately 10 m3 of differently treated slurry were stored in pilot scale slurry tanks. Emissions were followed for c. 80 days. After the storage period, slurries were applied to permanent grassland. Greenhouse gas emissions from slurry were mainly caused by methane emissions during storage and by nitrous oxide emissions after field application of manures. Mitigation of GHG emissions can be achieved by a reduction in slurry dry matter and easily degradable organic matter content. Ammonia emissions mainly occurred after field application. Untreated slurry emitted 226.8 g NH3 m−3 and 92.4 kg CO2 eq. m−3 (storage and field application). Slurry separation (liquid fraction and composting of the solid fraction) resulted in NH3 losses of 402.9 g m−3 and GHG losses of 58.5 kg CO2 eq. m−3. Anaerobic digestion was a very effective means to reduce GHG emissions. 37.9 kg CO2 eq. m−3 were lost. NH3 emissions were similar to those from untreated slurry. Covering the slurry store with a layer of chopped straw instead of a wooden cover increased NH3 emissions to 320.4 g m−3 and GHG emissions to 119.7 kg CO2 eq. m−3. Slurry aeration nearly doubled NH3 emissions compared to untreated slurry. GHG emissions were reduced to 53.3 kg CO2 eq. m−3. 相似文献
12.
《Journal of Loss Prevention in the Process Industries》2007,20(1):1-6
Results of a round-robin test on a mini-autoclave are reported and previously proposed criteria reviewed. Criteria based upon the results for three standard materials are now put forward. These standards-based criteria, in contrast to numerical criteria, theoretically allow any laboratory to utilize the data accumulated to date, irrespective of the equipment used. The practical requirement is that adequate discrimination can be achieved. Data to assess this are given. 相似文献
13.
《Atmospheric environment (Oxford, England : 1994)》2007,41(30):6356-6365
The objective of this paper is to show the methodology developed to estimate particle emissions from several typical activities of bulk handling in harbours. It is based on several field experiments carried out in the Harbour of Tarragona, where high time resolution monitors were deployed close to different areas of bulk solids handling operations. Monitors recorded particle concentrations and meteorological variables. A high-resolution dispersion model is used to estimate the emission rates that best fits the observations. Results were comparable to those obtained with the AP-42 (EPA). The new emission estimates are used as input for an emission model called EMIPORT. The model also employs AP-42 (EPA) emission factors as a complement. This work is one of the activities of the LIFE project called HADA (Herramienta Automática de Diagnóstico Ambiental or in English Automatic Tool for Environmental Diagnostic). 相似文献
14.
《Journal of Cleaner Production》2007,15(15):1441-1450
Two step ultrasonic dyeing of cotton and silk fabrics with natural dyes, Terminalia arjuna, Punica granatum, and Rheum emodi have been developed in which an enzyme is complexed with tannic acid first as a pretreatment. This was found to be comparable with one step simultaneous dyeing. The effectiveness of three enzymes—protease-amylase, diasterase and lipase was determined. The enzymatic treatment gave cotton and silk fabrics rapid dye adsorption kinetics and total higher adsorption than untreated samples for all the three dyes. The CIELab values also showed improvement by enzymatic treatment. The tannic acid-enzyme-dye combination method offers an environmentally benign alternative, ‘soft chemistry’ to the metal mordanted natural dyeing. 相似文献
15.
Christophe Pélabon Jean-Michel Gaillard Anne Loison Christine Portier 《Behavioral ecology and sociobiology》1995,37(5):311-319
We examined data on sex-specific differences in neonatal weight, litter size and adult female body weight in 32 populations of polygynous ungulates of 18 different species to test for the existence of a trade-off between sex-biased maternal care and the total amount of maternal expenditure. This corresponds to an extension of the hypothesis of Byers and Moodie (1990) that sex-biased maternal care is limited by a high level of maternal expenditure. We did not find any relationship between sex-biased care and two measures of total maternal expenditure. We highlighted high intraspecific variability in sex-biased care and very low intraspecific variability in total maternal expenditure. Even when this between-population variability in sex-biased care was accounted for, no relationship between sex-biased maternal care and maternal expenditure was detected. Apart from difficulties in finding suitable measures for both variables, two other reasons may account for the lack of a relationship between sex-biased maternal care and total maternal expenditure. Firstly, male offspring seem to be more affected than female offspring by harsh environmental conditions. This may lead to the variation observed in the extent of sex-specific differences in birth weight within a single species. If we assume that for a given maternal expenditure reproductive costs incurred by mothers are highest during harsh conditions, this could indicate the existence of a trade-off between sex-biased maternal care and maternal expenditure at the intra-specific level, thereby supporting the Byers and Moodie hypothesis. Secondly, polygyny is only a poor predictor of sex-biased care and factors such as compensatory growth or extended periods of growth may be expected to modify predictions for different species. Thus, environmental conditions and relative effects of maternal care on male and female lifetime reproductive success are better predictors of sex-biased care than total maternal expenditure.Communicated by P.M. Kappeler 相似文献
16.
The most widely used method for fetocide in late termination of pregnancy for fetal abnormalities (TOPFA) consists of injecting of potassium chloride (KCl) into the fetal heart and is likely to be painful after 22 weeks of gestation. We studied ten consecutive women undergoing TOPFA between 22 and 38 weeks. This technique for fetocide consisted of a single umbilical vein puncture under ultrasound guidance with injections of sufentanil 5 µg followed by KCl 2 g. No electrocardiographic modifications could be observed and maternal plasma potassium levels did not show any significant variation throughout the procedure. Fetal umbilical phlebotomy for fetal analgesia followed by fetocide therefore appears to be a safe procedure for the mother and allows the fetus to die without pain when late termination of pregnancy (TOP) is indicated. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
17.
V. Nataf M. V. Senat M. Albert L. Bidat P. de Mazancourt J. Roume L. Allard D. Le Tessier Y. Ville J. Selva 《黑龙江环境通报》2002,22(8):675-680
Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
18.
19.
Riviane R. Hora Claudie Doums Chantal Poteaux Renée Fénéron Jorge Valenzuela Jürgen Heinze Dominique Fresneau 《Behavioral ecology and sociobiology》2005,59(2):285-292
Social parasites exploit the worker force of colonies of other social insects to rear their own young. Social parasitism occurs in several Hymenoptera and is particularly common in several tribes of the ant subfamilies Myrmicinae and Formicinae. Here, we document the occurrence of miniaturized queens (microgynes) in colonies of Ectatomma tuberculatum, an ant belonging to the subfamily Ectatomminae. Behavioral observations and genetic analyses show that microgynes concentrate their reproductive efforts almost exclusively on the production of sexual offspring (microgynes and males), whereas the regular, large queens (macrogynes) produce workers in addition to sexuals. According to mitochondrial and nuclear markers, gene flow between microgynes and macrogynes is extremely limited. Whereas the co-occurrence of microgynes and macrogynes in the related species Ectatomma ruidum constitutes an intraspecific polymorphism associated with alternative dispersal tactics, microgynes found in colonies of E. tuberculatum appear to be a distinct species and to represent the first case of social parasitism in the poneromorph subfamilies of ants. 相似文献
20.