全文获取类型
收费全文 | 1426篇 |
免费 | 14篇 |
国内免费 | 17篇 |
专业分类
安全科学 | 73篇 |
废物处理 | 52篇 |
环保管理 | 240篇 |
综合类 | 230篇 |
基础理论 | 248篇 |
环境理论 | 3篇 |
污染及防治 | 427篇 |
评价与监测 | 107篇 |
社会与环境 | 60篇 |
灾害及防治 | 17篇 |
出版年
2023年 | 18篇 |
2022年 | 27篇 |
2021年 | 39篇 |
2020年 | 29篇 |
2019年 | 26篇 |
2018年 | 55篇 |
2017年 | 55篇 |
2016年 | 68篇 |
2015年 | 42篇 |
2014年 | 69篇 |
2013年 | 110篇 |
2012年 | 72篇 |
2011年 | 98篇 |
2010年 | 59篇 |
2009年 | 51篇 |
2008年 | 81篇 |
2007年 | 77篇 |
2006年 | 71篇 |
2005年 | 61篇 |
2004年 | 40篇 |
2003年 | 32篇 |
2002年 | 35篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1960年 | 2篇 |
1957年 | 2篇 |
1954年 | 3篇 |
排序方式: 共有1457条查询结果,搜索用时 15 毫秒
991.
Anna Donnla O'Hagan Johann Issartel Richard Fletcher Giles Warrington 《International journal of occupational safety and ergonomics》2016,22(2):165-172
Introduction. Working long duty hours has often been associated with increased risk of incidents and accidents in transport industries. Despite this, information regarding the intermediate relationship between duty hours and incident risk is limited. This study aimed to test a work hours/incident model to identify the interplay of factors contributing to incidents within the aviation industry. Methods. Nine hundred and fifty-four European-registered commercial airline pilots completed a 30-item survey investigating self-report attitudes and experiences of fatigue. Path analysis was used to test the proposed model. Results. The fit indices indicated this to be a good fit model (χ2?=?11.066, df?=?5, p?=?0.05; Comparative Fit Index?=?0.991; Normed Fit Index?=?0.984; Tucker–Lewis Index?=?0.962; Root Mean Square of Approximation?=?0.036). Highly significant relationships were identified between duty hours and sleep disturbance (r?=?0.18, p?0.001), sleep disturbance and fatigue in the cockpit (r?=?0.40, p?0.001), and fatigue in the cockpit and microsleeps in the cockpit (r?=?0.43, p?0.001). Discussion. A critical pathway from duty hours through to self-reported incidents in flight was identified. Further investigation employing both objective and subjective measures of sleep and fatigue is needed. 相似文献
992.
Prescribed burning is now a widely accepted bushfire hazard management strategy. While evidence points to reduced levels of public health harm compared to severe bushfire, smoke created by planned burns remains a community concern with need for evidence-based public health management. Findings are presented from an Australian study of community experiences of prescribed burns, associated smoke, and public health communications. We find that “place” influences how information is received and used for the management of the effects of planned burns; and that this is significant for human agency and community resilience. We provide recommendations for public health management. 相似文献
993.
Rory Coffey Michael J. Paul Jen Stamp Anna Hamilton Thomas Johnson 《Journal of the American Water Resources Association》2019,55(4):844-868
In this paper we review the published, scientific literature addressing the response of nutrients, sediment, pathogens, and cyanobacterial blooms to historical and potential future changes in air temperature and precipitation. The goal is to document how different attributes of water quality are sensitive to these drivers, to characterize future risk, to inform management responses, and to identify research needs to fill gaps in our understanding. Results suggest that anticipated future changes present a risk of water quality and ecosystem degradation in many United States locations. Understanding responses is, however, complicated by inherent high spatial and temporal variability, interactions with land use and water management, and dependence on uncertain changes in hydrology in response to future climate. Effects on pollutant loading in different watershed settings generally correlate with projected changes in precipitation and runoff. In all regions, increased heavy precipitation events are likely to drive more episodic pollutant loading to water bodies. The risk of algal blooms could increase due to an expanded seasonal window of warm water temperatures and the potential for episodic increases in nutrient loading. Increased air and water temperatures are also likely to affect the survival of waterborne pathogens. Responding to these challenges requires understanding of vulnerabilities, and management strategies to reduce risk. 相似文献
994.
Gerba Leta Girma Kelboro Till Stellmacher Kristof Van Assche Anna‐Katharina Hornidge 《Natural resources forum》2018,42(2):93-107
A public mobilization approach known as nikinake drives implementation and technology upscaling in Ethiopia's agricultural extension. This study investigates and describes the processes and effectiveness of nikinake as an extension method used for natural resource management (NRM). The paper draws on empirical field research conducted in Oromia and the southern region of Ethiopia by looking at nikinake in the context of a watershed management campaign in 2015 and 2016. Nikinake is used as an approach to mobilize the public and to promote the skills of farmers and development actors. In principle, the implementation of NRM is voluntary; however, it is largely planned top‐down and enforced through state actors and informal institutions. This study suggests effective integration of social mobilization with reliable extension and a paradigm shift in emphasis from spatial coverage to an effective outcome. Additionally, sustainability and scalability of NRM interventions could be ameliorated by improving experts’ technical skills, raising farmers’ awareness, improving an incentive system, building trust, and better integrating past watershed management and future planning activities. We reflect on the significance of the nikinake experience in Ethiopia for a broader theory of extension‐as‐mobilization for rural development. From the Ethiopian case, a more general recommendation emerges for extension‐as‐mobilization schemes. For long‐term development, it is worthwhile to consider the fit between yearly campaigns as ad hoc project organizations and the existing pattern of actors and institutions responsible for rural development. 相似文献
995.
Henricus F M Vester Deborah Lawrence J Ronald Eastman B L Turner Sophie Calmé Rebecca Dickson Carmen Pozo Florencia Sangermano 《Ecological applications》2007,17(4):989-1003
The southern Yucatán contains the largest expanse of seasonal tropical forests remaining in Mexico, forming an ecocline between the drier north of the peninsula and the humid Petén, Guatemala. The Calakmul Biosphere Reserve resides in the center of this region as part of the Mesoamerican Biological Corridor. The reserve's functions are examined in regard to land changes throughout the region, generated over the last 40 years by increasing settlement and the expansion and intensification of agriculture. These changes are documented from 1987/1988 to 2000, and their implications regarding the capacity of the reserve to protect the ecocline, forest habitats, and butterfly diversity are addressed. The results indicate that the current landscape matrix serves the biotic diversity of the reserve, with several looming caveats involving the loss of humid forests and the interruption of biota flow across the ecocline, and the amount and proximity of older forest patches beyond the reserve. The highly dynamic land cover changes underway in this economic frontier warrant an adaptive management approach that monitors the major changes underway in mature forest types, while the paucity of systematic ecological and environment-development studies is rectified in order to inform policy and practice. 相似文献
996.
997.
When released after clock-shift, homing pigeons fail to orient towards the home direction but display a consistent deflection of their initial orientation due to the difference between the real sun azimuth and the computed azimuth according to the subjective time of each single bird. It has been reported that the size of the observed deflection is frequently smaller than expected and a discussion on the possible factors affecting the size of deflection has emerged. Some authors have proposed that the major factor in reducing the deflection after clock-shift is the simultaneous use of both the magnetic and the sun compasses, giving true and erroneous information, respectively, about the home direction. Therefore, a magnetic disturbance, by impeding the use of the geomagnetic information in determining the home direction, is presumed to increase the size of the deflection up to the levels of the expectation. To test this hypothesis, we released three groups of clock-shifted birds from unfamiliar locations (unmanipulated pigeons, pigeons bearing magnets on their head, and pigeons bearing magnets on their back) together with a group of unshifted control birds. As no difference in the orientation of the three groups emerged, we were not able to confirm the hypothesis of the role of the magnetic compass in reducing the expected deflection after clock-shift.Communicated by W. Wiltschko 相似文献
998.
Habitat selection by the hydrothermal vent limpet, Lepetodrilus fucensis, in Northeast Pacific hydrothermal vent ecosystems, may influence its reproductive output, as it occupies habitats with varying
physico-chemical conditions that reflect the availability of nutritional resources. Histological techniques were used to determine
size at first reproduction, gametogenesis, reproductive output, and fecundity in relation to shell length (SL), through examination
of the gonads of male and female L. fucensis, collected from five different hydrothermal vent habitat types with different temperature anomalies and hydrothermal fluid
flow vigour: vigorous (VIG), diffuse (DIF), tubeworm bushes (TWB), peripheral (PER), and senescent areas (SEN). Both male
and female L. fucensis exhibited early maturity, with the first reproductive event occurring at 3.8 and 3.9 mm shell length, respectively. All stages
of gamete development were present in the gonads of males and females, suggesting continuous gametogenesis and asynchronous
reproduction in this species. Gametogenic maturity of limpets did not vary among actively venting habitats (VIG, DIF, TWB,
and PER), but was significantly lower in males and females from SEN habitats. Mean oocyte diameter was largest in females
from VIG habitats, and smallest in females from SEN habitats, than in those from the other habitats (DIF, TWB, and PER). Females
from actively venting habitats also had greater actual fecundity than those from senescent habitats. While the gametogenic
pattern of L. fucensis appears phylogenetically constrained, selection of actively venting habitats by L. fucensis maximizes its reproductive output. The multiple feeding strategies of L. fucensis may allow for a constant supply of energy to be allocated to reproduction in any habitat except senescent vents. Early maturity,
high fecundity, and continuous production of gametes suggest a reproductive strategy characteristic of an opportunistic species,
and may be contributing to the extremely abundant populations of L. fucensis observed in the Northeast Pacific vent ecosystem. 相似文献
999.
Summary. The purpose of this study was to identify plant volatiles that provide host location cues for adult females of the gall wasp Antistrophus rufus Gillette (Hymenoptera: Cynipidae). Larvae of this species inhabit flowering stems of the prairie perennial Silphium laciniatum L. (Asteraceae). Adult females responded to volatile compounds emitted by stems of S. laciniatum in field olfactometer bioassays. Plant volatiles were monoterpenes, including, in descending order of abundance, racemic - and -pinene (~50% + enantiomer for both), (+)-limonene, (–)-camphene, and -myrcene. In laboratory bioassays, females responded to aeration extracts of plant stems, the full blend of synthetic monoterpenes, and the four-component blend of -pinene, -pinene, (+)-limonene, and (–)-camphene. This monoterpene blend apparently serves as an olfactory cue for host plant location for female A. rufus and is the first such cue to be reported for a cynipid gall wasp. Species-specific ratios of plant monoterpenes may provide cues for gall wasp females to distinguish between plant species and choose appropriate hosts for oviposition. The olfactometer and bioassay techniques developed for this research may be useful for field bioassays of other types of minute arthropods. 相似文献
1000.
The return of a successful bumblebee forager stimulates nestmates to leave the nest and search for food. Here we investigate the mechanisms by which this happens. Successful Bombus terrestris foragers perform irregular runs in their nest, often lasting for several minutes. Run duration is at its maximum when food has just been discovered. Running likely serves to distribute a pheromone, since the information flow between "runners" and "recruits" can be disrupted by eliminating air exchange, while leaving other potential means of communication intact. In addition, nectar stores in the nest may be monitored continuously. A sudden influx of nectar into the nest also causes measurable increases in forager activity. The implications of bumblebee recruitment behavior for the evolution of communication in bees are discussed. 相似文献