全文获取类型
收费全文 | 117篇 |
免费 | 2篇 |
专业分类
安全科学 | 7篇 |
废物处理 | 5篇 |
环保管理 | 15篇 |
综合类 | 18篇 |
基础理论 | 31篇 |
环境理论 | 1篇 |
污染及防治 | 34篇 |
评价与监测 | 7篇 |
社会与环境 | 1篇 |
出版年
2022年 | 4篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有119条查询结果,搜索用时 343 毫秒
31.
Walker David I. Cross Lisa J. Stapleton Tina A. Jenkins Connaire L. Lees David N. Lowther James A. 《Food and environmental virology》2019,11(3):229-237
Food and Environmental Virology - Human noroviruses are the leading cause of viral gastroenteritis. In the absence of a practical culture technique for routine analysis of infectious noroviruses,... 相似文献
32.
33.
Escherichia coli is a ubiquitous component of the intestinal microflora of warm-blooded animals, and is an indicator of fecal contamination of surface waters. Ribotype profiling of E. coli is one of several genotypic methods that has been developed to determine the host origin of fecal bacteria. Like most genotypic methods of source tracking, ribotyping requires a host origin database to identify environmental isolates. To determine the extent of temporal variability of ribotypes and its effect on a host origin database, E. coli isolates were obtained from fecal samples of two herds of Black Angus steers at a long-term experimental site at four sampling times from October 1999 to July 2000. Fecal samples were taken from six randomly chosen steers at each time. At a similarity index of 90% as calculated by unweighted pair-group method using arithmetic averages (UPGMA), 240 ribotypes were identified from 451 E. coli isolates. Only 20 ribotypes (8.3%), comprising 33% of the total isolates, were shared among sampling times and were considered resident ribotypes. Two of the twenty resident ribotypes appeared at three sampling times, and the remaining eighteen appeared at two. The majority of the ribotypes, therefore, were transient and unique to each sampling time and steer. Both the apparent turnover of E. coli ribotypes and a clonal diversity index of 0.97 (indicative of extensive ribotype variability) suggest the necessity of ribotyping a large number E. coli isolates per host to establish a host origin database that is independent of temporal variability, or complete enough to be effective. 相似文献
34.
35.
Performance rating research about individual performance may not necessarily generalize to rating performance of dyads. Using data from the 1992 Winter Olympics, this study demonstrates that observed interdimensional correlations are higher when dyads rather than individuals are being rated, particularly when raters have the opportunity to form prior general impressions of ratees. Implications of these results are discussed. © 1998 John Wiley & Sons, Ltd. 相似文献
36.
Brima EI Jenkins RO Lythgoe PR Gault AG Polya DA Haris PI 《Journal of environmental monitoring : JEM》2007,9(1):98-103
Millions of people in some of the poorest regions of the world are exposed to high levels of arsenic through drinking contaminated water. It has been reported that development of cancer caused by arsenic exposure in such populations is dependent on dietary and nutritional factors which can modulate arsenic metabolism. Many people in arsenic exposed regions of Bangladesh and India practice fasting for at least one month every year when they refrain from consumption of food and fluid during daylight hours. How such practices may modulate arsenic metabolism has not been previously investigated. This study investigated this issue by determining total arsenic and its species in urine samples from a group of 29 unexposed volunteers at the beginning of the fasting and at the end of approximately 12 h of fasting period. Inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography (HPLC) coupled with ICP-MS was used to measure the total arsenic and arsenic speciation in the urine samples, respectively. The mean total levels of arsenic at the beginning of fasting (18.3 microg g(-1) creatinine) and at the end of approximately 12 h of fasting (17.7 microg g(-1) creatinine) did not differ significantly (p > 0.05). However, the percentages of urinary arsenic as the methylated arsenic species methylarsonate (MA) were found to be significantly different (p < 0.05) and this species was observed more frequently at the end of fasting, although its overall concentration was similar. There were no significant differences (p > 0.05) in both the concentrations and percentages of other urinary arsenic species detected, namely arsenobetaine (AB) and dimethylarsinate (DMA). Arsenite (As(III)) and arsenate (As(V)) were also analyzed, but were not detected. We conclude that fasting for a period of 12 h results in a significant increase in the percentage of urinary arsenic as MA, and its frequency of detection in the volunteers at the end of the fasting period is almost nine fold higher. This suggests that metabolism of arsenic is altered by fasting. 相似文献
37.
Neighborhood analyses of canopy tree competition along environmental gradients in New England forests. 总被引:2,自引:0,他引:2
Charles D Canham Michael J Papaik María Uriarte William H McWilliams Jennifer C Jenkins Mark J Twery 《Ecological applications》2006,16(2):540-554
We use permanent-plot data from the USDA Forest Service's Forest Inventory and Analysis (FIA) program for an analysis of the effects of competition on tree growth along environmental gradients for the 14 most abundant tree species in forests of northern New England, USA. Our analysis estimates actual growth for each individual tree of a given species as a function of average potential diameter growth modified by three sets of scalars that quantify the effects on growth of (1) initial target tree size (dbh), (2) local environmental conditions, and (3) crowding by neighboring trees. Potential growth of seven of the 14 species varied along at least one of the two environmental axes identified by an ordination of relative abundance of species in plots. The relative abundances of a number of species were significantly displaced from sites where they showed maximum potential growth. In all of these cases, abundance was displaced to the more resource-poor end of the environmental gradient (either low fertility or low moisture). The pattern was most pronounced among early successional species, whereas late-successional species reached their greatest abundance on sites where they also showed the highest growth in the absence of competition. The analysis also provides empirical estimates of the strength of intraspecific and interspecific competitive effects of neighbors. For all but one of the species, our results led us to reject the hypothesis that all species of competitors have equivalent effects on a target species. Most of the individual pairwise interactions were strongly asymmetric. There was a clear competitive hierarchy among the four most shade-tolerant species, and a separate competitive hierarchy among the shade-intolerant species. Our results suggest that timber yield following selective logging will vary dramatically depending on the configuration of the residual canopy, because of interspecific variation in the magnitude of both the competitive effects of different species of neighbors and the competitive responses of different species of target trees to neighbors. The matrix of competition coefficients suggests that there may be clear benefits in managing for specific mixtures of species within local neighborhoods within stands. 相似文献
38.
S W Hermanowicz R S Trussell R P Merlo D Jenkins 《Water environment research》2006,78(13):2524-6; discussion 2526-8
39.
The establishment and spread of a non-native species in an introduced range depends to a large extent on the performance of the species under the prevailing environmental conditions. The spawning, larval and spatfall periods of the invasive gastropod Crepidula fornicata were monitored in the intertidal zone at its northernmost range in Wales, UK, between February 2010 and January 2011. The duration of the reproductive season was similar to that recorded from more southerly European populations. Spawning and larval release occurred throughout most of the year even at low seawater temperatures of <7 °C, but benthic recruitment was observed over a much shorter period at seawater temperatures >16 °C. Recruitment was low and likely controlled by post-settlement mortality. These observations suggest that C. fornicata’s northwards spread in Welsh waters will not be limited by seawater temperature negatively affecting reproduction, but by processes acting after larval release. These data show the importance of incorporating settlement and post-settlement processes into studies on recruitment success when aiming to predict the potential spread of a potentially harmful invader such as C. fornicata. 相似文献
40.
Many models of selection predict that populations will lose variation in traits that affect fitness. Nonetheless, phenotypic variation is commonly observed in natural populations. We tested the influences of competition and spatial heterogeneity on behavioral variation within and among populations of Merriam's kangaroo rats (Dipodomys merriami) and tested for the differential expression of trait correlations. We found that populations of D. merriami exhibited more aggression at sites with more competition. Contrary to theoretical predictions and empirical results in other systems, the sites with the greatest spatial heterogeneity and highest levels of competition did not exhibit the most behavioral variation among individuals. However, the greatest within-individual behavioral variability in boldness (response to cues of predator presence) was exhibited where spatial heterogeneity was highest. Aggression and boldness of D. merriami were highly repeatable, that is, individuals behaved in a consistent manner over time, and the two behaviors were also highly correlated. Interestingly, the strength of this correlation was greatest where the competitive community was least diverse. These findings add to increasing evidence that natural populations of animals exhibit patterns of behavioral covariance, or personality structure, and suggest that competitive variation may act to erode personality structure. 相似文献