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81.
INTRODUCTION: The use of hand-held cellular (mobile) phones while driving has stirred more debate, passion, and research than perhaps any other traffic safety issue in the past several years. There is ample research showing that the use of either hand-held or hands-free cellular phones can lead to unsafe driving patterns. Whether or not these performance deficits increase the risk of crash is difficult to establish, but recent studies are beginning to suggest that cellular phone use elevates crash risk. METHODS: The purpose of this study was to assess changes in the rate of hand-held cellular phone use by motor-vehicle drivers on a statewide level in Michigan. This study presents the results of 13 statewide surveys of cellular phone use over a 4-year period. Hand-held cellular phone use data were collected through direct observation while vehicles were stopped at intersections and freeway exit ramps. Data were weighted to be representative of all drivers traveling during daylight hours in Michigan. RESULTS: The study found that driver hand-held cellular phone use has more than doubled between 2001 and 2005, from 2.7% to 5.8%. This change represents an average increase of 0.78 percentage points per year. The 5.8% use rate observed in 2005 means that at any given daylight hour, around 36,550 drivers were conversing on cellular phones while driving on Michigan roadways. The trend line fitted to these data predicts that by the year 2010, driver hand-held cellular phone use will be around 8.6%, or 55,000 drivers at any given daylight hour. CONCLUSIONS: These results make it clear that cellular phone use while driving will continue to be an important traffic safety issue, and highlight the importance of continued attempts to generate new ways of alleviating this potential hazard. 相似文献
82.
Semiu A. Lawal W. Edgar. Watt 《Journal of the American Water Resources Association》1996,32(6):1159-1166
ABSTRACT: The implications of fitting distributions with non-zero lower limits to low flow data are examined. The 3-parameter Weibull distribution is fitted to annual minimum flow series from 60 long term stations in Canada. The relations between the estimated lower limit and three sampling variables (skewness, smallest, and largest observations) were investigated. The lower limit strongly depends on the sample skewness; it varies directly with the sample skewness, which in turn is highly influenced by the largest observation. For a given skewness, the value of the estimated lower limit is determined by the value of the smallest observation. Therefore, the lower limit cannot be accurately determined, and the resulting low flow estimates will be either too small or too high. 相似文献
83.
Jonathan Pickering 《Journal of Environmental Policy & Planning》2020,22(1):59-71
ABSTRACTRecent debates about the concept of planetary boundaries recall longstanding concerns about whether ecological limits are compatible with ecological democracy. The planetary boundaries framework (originally set out in Rockström et al., 2009a, 2009b) defines values for key Earth-system processes such as climate change and biodiversity that aim to maintain a ‘safe’ distance from thresholds or levels that could endanger human wellbeing. Despite having a significant impact in policy debates, the framework has been criticised as implying an expert-driven approach to governing global environmental risks that lacks democratic legitimacy. Drawing on research on deliberative democracy and the role of science in democratic societies, we argue that planetary boundaries can be interpreted in ways that remain consistent with democratic decision-making. We show how an iterative, dialogical process to formulate planetary boundaries and negotiate ‘planetary targets’ could form the basis for a democratically legitimate division of labour among experts, citizens and policy-makers in evaluating and responding to Earth-system risks. Crucial to this division of evaluative labour is opening up space for deliberative contestation about the value judgments inherent in collective responses to Earth-system risks, while also safeguarding the ability of experts to issue warnings about what they consider to be unacceptable risks. 相似文献
84.
井下地脉动测试是一种新型的原位测试手段,本文简介了这种测试方法的要点,并对测试数据的工程价值与应用方法进行了讨论。 相似文献
85.
The Influence of Synoptic-scale Air Flow and Local Circulation on the Dust Layer Height in the North of the Taklimakan Desert 总被引:1,自引:0,他引:1
Nobumitsu Tsunematsu Kenji Kai Takuya Matsumoto 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):175-193
The present study investigates the influences of synoptic-scale air flows and local wind circulations on the dust layer height
(DLH) in the Taklimakan Desert, based on lidar observations performed in the north of the desert in March 2003. The DLH fluctuates
approximately every three days between 2500 m (above sea level) and 5000 m, including diurnal variations. Meteorological analyses
and numerical simulations show that the three-day fluctuation of DLH corresponds with variations in synoptic-scale air flows
over the Taklimakan Desert, and the diurnal variations are linked to downdrafts and updrafts that are formed over the north
of the desert as part of local circulations. When strong northerly winds prevail in the upper troposphere and a developed
valley wind blows toward the Tienshan Mountains in the lower troposphere, the downdrafts strengthen in the middle troposphere
over the north of the desert, lowering the DLH to about 2500 m. In contrast, the DLH rises to about 5000 m when the updrafts
develop between strong southerly winds in the upper troposphere and a developed mountain wind blowing from the Tienshan Mountains.
Simulations for the local circulation behavior without the presence of the Tienshan Mountains demonstrate that the valley
and mountain winds on the southern slope of the Tienshan Mountains control the intensity of the downdrafts and updrafts, thereby
influencing the DLH over the north of the Taklimakan Desert. 相似文献
86.
87.
研究分析了高邮地磁台1980~2001年观测资料的加卸载响应比异常与江苏及邻近地区ML5.0以上地震之间的关系,提出了适用于高邮地磁台的地震分析预报参数,并对其内检预报效能进行了评价。 相似文献
88.
89.
汇源大厦托换工程影响巨大,其由立柱拆除引起的沉降监测属高精度要求的大型建筑物变形测量,是托换工程实施的重要保障,结合对托换梁、柱的结构受力分析,分3层布设监测点、依工程进展状况制定合理的观测周期,并采取重点监测与验证相结合的原则,使用精密水准仪配加游标卡尺的特制标卡尺的的特制标尺,多台仪器同时观测等方法,及时反馈了梁柱变形动态,指导拆除及托换进程,保证了工程的顺利进行。 相似文献
90.