首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5040篇
  免费   140篇
  国内免费   63篇
安全科学   280篇
废物处理   174篇
环保管理   1276篇
综合类   550篇
基础理论   1381篇
环境理论   8篇
污染及防治   1024篇
评价与监测   320篇
社会与环境   175篇
灾害及防治   55篇
  2023年   58篇
  2022年   59篇
  2021年   57篇
  2020年   65篇
  2019年   69篇
  2018年   127篇
  2017年   137篇
  2016年   181篇
  2015年   123篇
  2014年   161篇
  2013年   418篇
  2012年   235篇
  2011年   317篇
  2010年   207篇
  2009年   238篇
  2008年   269篇
  2007年   258篇
  2006年   231篇
  2005年   199篇
  2004年   186篇
  2003年   152篇
  2002年   140篇
  2001年   96篇
  2000年   95篇
  1999年   69篇
  1998年   75篇
  1997年   60篇
  1996年   66篇
  1995年   78篇
  1994年   76篇
  1993年   68篇
  1992年   60篇
  1991年   41篇
  1990年   35篇
  1989年   40篇
  1988年   30篇
  1987年   40篇
  1986年   40篇
  1985年   40篇
  1984年   45篇
  1983年   45篇
  1982年   55篇
  1981年   43篇
  1980年   33篇
  1979年   16篇
  1978年   29篇
  1977年   16篇
  1976年   13篇
  1975年   8篇
  1971年   9篇
排序方式: 共有5243条查询结果,搜索用时 281 毫秒
821.

Objective

This study compares construction industry groups in Washington State by injury severity and cost, and ranks industry groups according to potential for prevention.

Methods

All Washington State workers' compensation compensable claims with date of injury between 2003 and 2007 were classified into North American Industrial Classification System (NAICS) industry groups. Claims were then aggregated by injury type and industry groups were ranked according to a prevention index (PI). The PI is the average of the rank orders of the claim count and the claim incidence rate. A lower PI indicates a higher need for prevention activities. The severity rate was calculated as the number of days of time loss per 10,000 full-time equivalents (FTEs).

Results

For all injury types, construction industry groups occupy 7 of the top 15 PI ranks in Washington State. The severity rate among construction industry groups was twice that for non-construction groups for all injury types. Foundation, structure, and building exterior contractors (NAICS 2381) ranked highest in prevention potential and severity among construction industry groups for most common injury types including falls from elevation, fall on same level, struck by/against, and musculo-skeletal disorders of the neck, back, and upper extremity (WMSDs). Median claim costs by injury type were generally higher among construction industry groups.

Conclusions

The construction industry in Washington State has a high severity rate and potential for prevention. The methods used for characterizing these industry groups can be adapted for comparison within and between other industries and states.

Impact on Industry

These data can be used by industry groups and employers to identify higher cost and higher severity injury types. Knowledge about the relative frequencies and costs associated with different injury types will help employers and construction industry associations make better informed decisions about where prevention efforts are most needed and may have the greatest impact. The results of this study can also be used by industry stakeholders to cooperatively focus on high cost and high severity injuries and explore best practices, interventions, and solutions as demonstrated by efforts to prevent musculoskeletal disorders in masonry (Entzel, Albers, & Welch, 2007). Initiating construction industry groups to focus on high cost and high severity injuries may also help prevent other types of injuries.  相似文献   
822.
Recent theory regarding the nature of organizational commitment suggests that viewing it as comprised of two dimensions, value commitment and continuance commitment, is of theoretical and practical value. This field study found the differential antecedents of these two commitment dimensions to be consistent with the March and Simon (1958) framework using the two-dimensional organizational commitment questionnaire from Mayer and Schoorman (1992). Organizational tenure, retirement benefits, education, and age were more highly correlated with continuance commitment, while felt participation, perceived prestige, job involvement, and role ambiguity were more highly correlated with value commitment. Analysis using LISREL 7 supported the pattern of relationships between the antecedents and the two commitment dimensions. © 1998 John Wiley & Sons, Ltd.  相似文献   
823.
Amounts of pesticides reaching target pests: Environmental impacts and ethics   总被引:13,自引:0,他引:13  
Less than 0.1% of pesticides applied for pest control reach their target pests. Thus, more than 99.9% of pesticides used move into the environment where they adversely affect public health and beneficial biota, and contaminate soil, water, and the atmosphere of the ecosystem. Improved pesticide application technologies can improve pesticide use efficiency and protect public health and the environment.  相似文献   
824.
A field-based system used to quantify the response of acid grassland to reduced atmospheric nitrogen and sulphur deposition, and to investigate the effects of elevated soil temperature on acid grassland development is described. The system is based on 12 retractable roofs, covering undisturbed experimental plots of acid grassland and three controls. Nine roofs are used to exclude natural precipitation and three roofs used to retain emitted IR radiation at night. An irrigation system has been developed to simulate natural precipitation, allowing for the application of specific treatment regimes of ambient, reduced nitrogen and reduced nitrogen/sulphur deposition beneath the nine rain exclusion plots. Plant, soil parameters, leachate chemistry and gaseous fluxes are being monitored and initial results on soil water chemistry are described. Warming appeared to enhance nitrate concentrations in soil water but this was not sustained beyond the first year of treatment. In contrast, the deposition reduction treatments decreased soil water nitrate concentrations within a few weeks of reducing deposition. This was not observed for other solutes such as sulphate or ammonium suggesting a more direct link between deposition of nitrate and leaching losses.  相似文献   
825.
Deep learning (DL) models are increasingly used to make accurate hindcasts of management-relevant variables, but they are less commonly used in forecasting applications. Data assimilation (DA) can be used for forecasts to leverage real-time observations, where the difference between model predictions and observations today is used to adjust the model to make better predictions tomorrow. In this use case, we developed a process-guided DL and DA approach to make 7-day probabilistic forecasts of daily maximum water temperature in the Delaware River Basin in support of water management decisions. Our modeling system produced forecasts of daily maximum water temperature with an average root mean squared error (RMSE) from 1.1 to 1.4°C for 1-day-ahead and 1.4 to 1.9°C for 7-day-ahead forecasts across all sites. The DA algorithm marginally improved forecast performance when compared with forecasts produced using the process-guided DL model alone (0%–14% lower RMSE with the DA algorithm). Across all sites and lead times, 65%–82% of observations were within 90% forecast confidence intervals, which allowed managers to anticipate probability of exceedances of ecologically relevant thresholds and aid in decisions about releasing reservoir water downstream. The flexibility of DL models shows promise for forecasting other important environmental variables and aid in decision-making.  相似文献   
826.
Harmful algal blooms (HABs) diminish the utility of reservoirs for drinking water supply, irrigation, recreation, and ecosystem service provision. HABs decrease water quality and are a significant health concern in surface water bodies. Near real-time monitoring of HABs in reservoirs and small water bodies is essential to understand the dynamics of turbidity and HAB formation. This study uses satellite imagery to remotely sense chlorophyll-a concentrations (chl-a), phycocyanin concentrations, and turbidity in two reservoirs, the Grand Lake O′ the Cherokees and Hudson Reservoir, OK, USA, to develop a tool for near real-time monitoring of HABs. Landsat-8 and Sentinel-2 imagery from 2013 to 2017 and from 2015 to 2020 were used to train and test three different models that include multiple regression, support vector regression (SVR), and random forest regression (RFR). Performance was assessed by comparing the three models to estimate chl-a, phycocyanin, and turbidity. The results showed that RFR achieved the best performance, with R2 values of 0.75, 0.82, and 0.79 for chl-a, turbidity, and phycocyanin, while multiple regression had R2 values of 0.29, 0.51, and 0.46 and SVR had R2 values of 0.58, 0.62, and 0.61 on the testing datasets, respectively. This paper examines the potential of the developed open-source satellite remote sensing tool for monitoring reservoirs in Oklahoma to assess spatial and temporal variations in surface water quality.  相似文献   
827.
The purpose of this investigation was to analyze the relationship between four interviewer‐related factors and the validity of the employment interview. Using a regression approach to meta‐analysis, an analysis of 120 interview studies with a total sample size of 18,158 suggested that: (1) training should be provided to interviewers regardless of whether the interview itself (i.e. the questions and rating scales) is structured; (2) the same interviewer should be used across all applicants, especially when the interview itself is not highly structured; and (3) using a panel of interviewers does not contribute to validity, and may actually have a detrimental effect. Results for the fourth interviewer factor, taking notes during the interview, were inconclusive. Limitations and directions for future research are noted. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   
828.
Marine ecosystems are under high demand for human use, giving concerns about how pressures from human activities may affect their structure, function, and status. In Europe, recent developments in mapping of marine habitats and human activities now enable a coherent spatial evaluation of potential combined effects of human activities. Results indicate that combined effects from multiple human pressures are spread to 96% of the European marine area, and more specifically that combined effects from physical disturbance are spread to 86% of the coastal area and 46% of the shelf area. We compare our approach with corresponding assessments at other spatial scales and validate our results with European-scale status assessments for coastal waters. Uncertainties and development points are identified. Still, the results suggest that Europe’s seas are widely disturbed, indicating potential discrepancy between ambitions for Blue Growth and the objective of achieving good environmental status within the Marine Strategy Framework Directive.Supplementary informationThe online version of this article (10.1007/s13280-020-01482-x) contains supplementary material, which is available to authorized users.  相似文献   
829.
830.
The currant clearwing Synanthedon tipuliformis (Clerck) (Sesiidae) is a worldwide pest of black currants, Ribes nigrum. This moth has been observed to feed on nectar of inflorescences of Canada thistles, Cirsium arvense (L.) Scop. This work was undertaken to identify floral compound(s) produced by Canada thistles inflorescences that mediate the response of the currant clearwing. Floral volatiles were collected during the day and analysed by coupled gas chromatography/electroantennographic detection (GC/EAD) and gas chromatography/mass spectrometry (GC/MS). Three compounds consistently elicited EAD response from moth antennae and were identified by GC/MS as phenylacetaldehyde, methyl salicylate and dimethyl salicylate. When the compounds were tested individually or in various combinations in field trapping experiments, a 3-component blend attracted the largest number of female and male currant clearwings. Subsequent field trapping experiments were conducted to determine the optimal attraction dose for the ternary blend using three loadings of 1, 10 and 100 mg loaded into a polyethylene sachet. The highest catches were in traps baited with the 100 mg loading. In all trials, males and mated females were caught in significant numbers, while very low numbers of virgin females were found in the traps. In recent years the efficacy of mating disruption against currant clearwing has been reported as declining. The new kairomone blend identified in this study can be used with the sex pheromone to provide an effective control option for this important pest.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号