全文获取类型
收费全文 | 3955篇 |
免费 | 33篇 |
国内免费 | 14篇 |
专业分类
安全科学 | 87篇 |
废物处理 | 251篇 |
环保管理 | 290篇 |
综合类 | 494篇 |
基础理论 | 807篇 |
环境理论 | 7篇 |
污染及防治 | 1427篇 |
评价与监测 | 367篇 |
社会与环境 | 262篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 47篇 |
2022年 | 104篇 |
2021年 | 153篇 |
2020年 | 62篇 |
2019年 | 65篇 |
2018年 | 154篇 |
2017年 | 148篇 |
2016年 | 215篇 |
2015年 | 126篇 |
2014年 | 243篇 |
2013年 | 378篇 |
2012年 | 276篇 |
2011年 | 277篇 |
2010年 | 210篇 |
2009年 | 135篇 |
2008年 | 217篇 |
2007年 | 251篇 |
2006年 | 184篇 |
2005年 | 154篇 |
2004年 | 111篇 |
2003年 | 95篇 |
2002年 | 86篇 |
2001年 | 48篇 |
2000年 | 38篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1988年 | 3篇 |
1970年 | 3篇 |
1967年 | 5篇 |
1966年 | 5篇 |
1965年 | 4篇 |
1964年 | 11篇 |
1963年 | 5篇 |
1962年 | 5篇 |
1961年 | 7篇 |
1960年 | 5篇 |
1959年 | 8篇 |
1958年 | 18篇 |
1957年 | 8篇 |
1956年 | 3篇 |
1955年 | 5篇 |
1931年 | 2篇 |
排序方式: 共有4002条查询结果,搜索用时 129 毫秒
361.
Kacániová M Fatrcová-Sramková K Nozková J Melich M Kadasi-Horáková M Knazovická V Felsöciová S Kunová S Máriássyová M 《Journal of environmental science and health. Part. B》2011,46(1):92-96
The purpose of the study was to examine the antiradical activity of 11 natural honeys and to evaluate the antifungal properties of honey. Honey samples (10) were collected from different locations of Slovak Republic. Honeys were native to different plant species of Robinia pseudoacaccia, Brassica napus subs. napus, Castanea sativa Mill. Thymus serpyllum vulgaris and the other samples had multifloral origin. The low antiradical activitity in honey samples was determined. The best results were found in thyme honey from Rhodos (11.84 %) and Castanea honey from Nitra (10.61 %). The lowest antiradical activity was found in Acacia honey and determined to be 7.62 %. Statistically significant differences (P< 0.001) were found among thyme/Rhodos and Castanea/Nitra. The antifungal activities of honey samples were tested by 10 %, 25 % and 50 % (by mass per volume) concentration against fungi Penicillium crustosum, P. expansum, P. griseofulvum, P. raistrickii and P. verrucosum and by the agar well diffusion method. The solutions containing 10 % (by mass per volume) of honey did not have any effect on the growth of fungi. The strongest antifungal effect was shown by 50 % honey concentration against P. raistrickii. 相似文献
362.
González-Santiago O Badillo-Castañeda CT Kahl JD Ramírez-Lara E Balderas-Renteria I 《Journal of the Air & Waste Management Association (1995)》2011,61(5):573-579
The Monterrey Metropolitan Area (MMA) is the third largest city in Mexico. Few studies have been carried out regarding its air pollution. The aim of this study was to analyze the temporal behavior of PM10 (particulate matter < or =10 microm in aerodynamic diameter). Data reported by the "Sistema Integral de Monitoreo Ambiental" (Integrated Environmental Monitoring System) network from 2006 to 2008 were used. PM10 levels were compared among the stations by year, season, and day of week. A bootstrap technique was used to obtain subsamples to which Student's t test and ANOVA were applied. PM10 levels were high and exceeded the annual limit of 50 microg/m3 set up by the Mexican standard Norma Oficial Mexicana NOM-025-SSA1-1993. These levels could have serious health effects. The southwest zone of MMA had the highest levels of PM10 during the period studied. Winter was the most polluted season, and summer was the least polluted season. Thursday and Friday were the most polluted days, and Sunday was the least polluted day. The hours with the highest levels of PM10 were 8:00 to 10:00 a.m., whereas nighttime hours were the cleanest. 相似文献
363.
Patricia Blanco-Piñeiro M. Pino Díaz-Pereira Aurora Martínez Vidal 《International journal of occupational safety and ergonomics》2018,24(2):316-323
Objective. Bad posture increases the risk that a musician may suffer from musculoskeletal disorders. This study compared posture quality required by different instruments or families of instruments. Methods. Using an ad-hoc postural observation instrument embracing 11 postural variables, four experts evaluated the postures of 100 students attending a Spanish higher conservatory of music. Results. The agreement of the experts’ evaluations was statistically confirmed by a Cohen's κ value between 0.855 and 1.000 and a Kendall value between 0.709 and 1.000 (p?0.001 in all cases). Moreover, χ2 tests revealed significant association between instrument families and seated posture with respect to pelvic attitude, dorsal curvature and head alignment in both sagittal and frontal planes. This analysis also showed an association between instrument families and standing posture with respect to the frontal plane of the axis of gravity, pelvic attitude, head alignment in the frontal plane, the sagittal plane of the shoulders and overall posture. Conclusions. While certain postural defects appear to be common to all families of instruments, others are more characteristic of some families than others. The instrument associated with the best posture quality was the bagpipe, followed by percussion and strings. 相似文献
364.
365.
Katarzyna?Wojczulanis-JakubasEmail authorView authors OrcID profile Ma?gorzata?E.?Chrostek Frédéric?Jiguet Carlos?Zumalacárregui?Martínez David?Miguélez Júlio?M.?Neto 《Die Naturwissenschaften》2017,104(11-12):101
Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species. 相似文献
366.
Faith E. Bartz Domonique Watson Hodge Norma Heredia Anna Fabiszewski de Aceituno Luisa Solís Lee-Ann Jaykus Santos Garcia Juan S. Leon 《Food and environmental virology》2016,8(3):221-226
Somatic coliphages were quantified in 459 produce and environmental samples from 11 farms in Northern Mexico to compare amounts of somatic coliphages among different types of fresh produce and environmental samples across the production steps on farms. Rinsates from cantaloupe melons, jalapeño peppers, tomatoes, and the hands of workers, soil, and water were collected during 2011–2012 at four successive steps on each farm, from the field before harvest through the packing facility, and assayed by FastPhage MPN Quanti-tray method. Cantaloupe farm samples contained more coliphages than jalapeño or tomato (p range <0.01–0.03). Across production steps, jalapeños had higher coliphage percentages before harvest than during packing (p = 0.03), while tomatoes had higher coliphage concentrations at packing than all preceding production steps (p range <0.01–0.02). These findings support the use of targeted produce-specific interventions at multiple points in the process of growing and packing produce to reduce the risk of enteric virus contamination and improve food safety during fruit and vegetable production. 相似文献
367.
Mouna Hassine-Zaafrane Khira Sdiri-Loulizi Jérôme Kaplon Imen Ben Salem Pierre Pothier Mahjoub Aouni Katia Ambert-Balay 《Food and environmental virology》2014,6(2):125-131
Noroviruses (NoVs) are responsible for numerous cases of waterborne and foodborne gastroenteritis every year. They are released in the sewage and their detection in this environment can reflect the epidemiology of the viral strains circulating in the community. A three-year (2007–2010) survey was conducted in order to evaluate the presence of human NoVs using RT-PCR in 518 sewage samples collected at the entrance and exit of two biological sewage treatment plants located in Monastir region, Tunisia. In this study, we aimed to genetically characterize the most prevalent GI and GII NoV strains, in order to obtain a rough estimate of the efficacy of disinfection treatments and to compare the results with clinical data documented in the same area during the same period. This work confirms the wide circulation and the genetic diversity of NoVs in Tunisia and the widespread distribution of NoV variants in both raw and treated wastewater. Indeed, NoV was detected in 192 (37.1 %) sewage samples, among them mixed infections with group A rotavirus were detected in 125 (65.1 %) cases. The genotypes of the GI NoVs were GI.1, GI.2, GI.4, GI.5, and GI of unassigned genotype (GI.UA), and the genotypes of the GII NoVs were all GII.12. This study enhances the currently poor environmental virological data gathered in Tunisia, demonstrates the benefit of environmental surveillance as a tool to determine the epidemiology of NoVs circulating in a given community, and underlines the need for the design and support of similar long-term studies in our country, in order to compensate for the absence of a national surveillance system for gastroenteric viruses. 相似文献
368.
Dimensional analysis and scaling in mechanical mixing for fabrication of metal matrix nanocomposites
S. García-Rodríguez N. Alba-Baena N.M. Rudolph J. Wellekoetter X.C. Li T.A. Osswald 《Journal of Manufacturing Processes》2012,14(3):388-392
For a successful enhancement of mechanical properties of metal matrix nanocomposites, a homogeneous nanoparticle dispersion and distribution in the solidified metal is required. Mechanical mixing can be used for initial break-up of agglomerates, and its study can be simplified with dimensional analysis. Using this technique, mixing time and vortex height were assessed while varying fluid properties, impeller angle, and angular speed. Three relevant dimensionless numbers were recognized: the Reynolds (Re), Froude and Galilei (Ga) numbers. Based on blade and impeller shaft angles, a modified Froude number (Fr*) was defined. These parameters were calculated experimentally, varying angular speed from 200 to 1000 rpm for three different impeller angles: 0°, 15° and 30°. This procedure was performed with three fluids: water, and two aqueous glycerin solutions (25% and 50% by volume). Digital images were taken and processed to measure vortex height. Mixing time was measured for water at 0° impeller angle, angular speed ranging from 200 to 1200 rpm. Results showed an optimal dimensionless mixing time with respect to Re. A linear relationship was found between dimensionless vortex height and Fr*. The first had a second order polynomial relationship with the product ReFr*, regardless of impeller angle. This relationship, together with the Ga, specific for each fluid, allows scaling the results to other fluids such as molten pure aluminum. This study allows experimenting in simpler systems that involve transparent fluids, room temperature and low cost, to then elaborate a prediction of vortex height in fluids where measurements are difficult and costly, such as molten metals. 相似文献
369.
370.
Gergely Hegyi Eszter Szöllősi Susanne Jenni-Eiermann János Török Marcel Eens László Zsolt Garamszegi 《Die Naturwissenschaften》2010,97(6):567-576
The information content of a sexual signal may predict its importance in a multiple signal system. Many studies have correlated
sexual signal expression with the absolute levels of nutrient reserves. In contrast, the changes of nutrient reserves associated
with signal expression are largely unknown in the wild due to technical limitations although they are important determinants
of signal information content. We compared two visual and eight acoustic sexual traits in male collared flycatchers to see
whether the nutritional correlates of expression predict the role of the signal in sexual selection. We used single point
assays of plasma lipid metabolites to estimate short-term changes in nutritional state in relation to sexual trait expression
during courtship. As a measure of sexual selection, we estimated the relationship with pairing latency after arrival in a
4-year dataset. Males which found a mate rapidly were characterized by large wing and forehead patches, but small song strophe
complexity and small figure repertoire size. Traits more strongly related to pairing latency were also more closely related
to changes in nutrient reserves. This indicates a link between signal role and information content. Small wing patches and,
surprisingly, complex songs seemed to indicate poor phenotypic quality and were apparently disfavoured at mate acquisition
in our population. Future studies of the information content of sexual traits, especially dynamic traits such as song, may
benefit from the use of plasma metabolite profiles as non-invasive indicators of short-term changes in body condition. 相似文献