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   21123篇
  免费   183篇
  国内免费   385篇
安全科学   491篇
废物处理   915篇
环保管理   2370篇
综合类   4393篇
基础理论   5038篇
环境理论   6篇
污染及防治   5201篇
评价与监测   1570篇
社会与环境   1592篇
灾害及防治   115篇
  2022年   244篇
  2021年   199篇
  2020年   135篇
  2019年   188篇
  2018年   323篇
  2017年   342篇
  2016年   481篇
  2015年   365篇
  2014年   611篇
  2013年   1608篇
  2012年   680篇
  2011年   903篇
  2010年   730篇
  2009年   808篇
  2008年   903篇
  2007年   908篇
  2006年   792篇
  2005年   722篇
  2004年   689篇
  2003年   681篇
  2002年   654篇
  2001年   869篇
  2000年   550篇
  1999年   353篇
  1998年   217篇
  1997年   232篇
  1996年   264篇
  1995年   297篇
  1994年   257篇
  1993年   209篇
  1992年   230篇
  1991年   244篇
  1990年   233篇
  1989年   207篇
  1988年   218篇
  1987年   162篇
  1986年   174篇
  1985年   187篇
  1984年   180篇
  1983年   166篇
  1982年   171篇
  1981年   179篇
  1980年   126篇
  1979年   136篇
  1978年   130篇
  1976年   123篇
  1974年   134篇
  1973年   119篇
  1972年   135篇
  1967年   126篇
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
671.
The focus of the present study is on the implementation and some of the results of an evaluation of a safety culture campaign that partly was aimed at increasing workmate interventions (care). I focus on three groups either working on or with a Norwegian offshore platform: onshore managers, crane operators and process operators. The research questions are: “Has the safety culture campaign contributed to new safety cultures related to care in the three groups, why/why not and what can we learn from this?”. The study indicates that two of the groups have developed new safety cultures that sensitize them to new hazards, motivate and legitimize new preventive practices. In accordance with the interpretive approach to culture in organizations, these changes are discussed in light of members’ of each group’s negotiation over the meaning and relevance of campaign efforts on workmate interventions. Lessons that can be learned from the study are discussed.  相似文献   
672.
Green specifications constitute one of the important elements in green construction. New sustainability requirements and changing priorities in construction management have spurred the emerging green specifications to a faster pace of development. A cross-sectional survey has been conducted in Hong Kong in 2007 to identify principal factors leading to the success of preparing green specifications. Based on extensive construction management literature, 20 variables concerning sustainable construction were summarized. Using the Mann–Whitney U-test, the subtle differences between stakeholders in specifying construction work have been detected even with the high consistency of the responses among the groups. Moreover, five independent factors for successful specification of green construction have been categorized by factor analysis. They are related to (1) green technology and techniques, (2) reliability and quality of specification, (3) leadership and responsibility, (4) stakeholder involvement, and (5) guide and benchmarking systems. Whilst the first and fourth factors are generally more important, different stakeholder groups have different emphases. The results of the survey have been validated against established principles.  相似文献   
673.
The phenomenon of Batesian mimicry, where a palatable animal gains protection against predation by resembling an unpalatable model, has been a core interest of evolutionary biologists for 150 years. An extensive range of studies has focused on revealing mechanistic aspects of mimicry (shared education and generalization of predators) and the evolutionary dynamics of mimicry systems (co‐operation vs. conflict) and revealed that protective mimicry is widespread and is important for individual fitness. However, according to our knowledge, there are no case studies where mimicry theories have been applied to conservation of mimetic species. Theoretically, mimicry affects, for example, frequency dependency of predator avoidance learning and human induced mortality. We examined the case of the protected, endangered, nonvenomous smooth snake (Coronella austriaca) that mimics the nonprotected venomous adder (Vipera berus), both of which occur in the Åland archipelago, Finland. To quantify the added predation risk on smooth snakes caused by the rarity of vipers, we calculated risk estimates from experimental data. Resemblance of vipers enhances survival of smooth snakes against bird predation because many predators avoid touching venomous vipers. Mimetic resemblance is however disadvantageous against human predators, who kill venomous vipers and accidentally kill endangered, protected smooth snakes. We found that the effective population size of the adders in Åland is very low relative to its smooth snake mimic (28.93 and 41.35, respectively).Because Batesian mimicry is advantageous for the mimic only if model species exist in sufficiently high numbers, it is likely that the conservation program for smooth snakes will fail if adders continue to be destroyed. Understanding the population consequences of mimetic species may be crucial to the success of endangered species conservation. We suggest that when a Batesian mimic requires protection, conservation planners should not ignore the model species (or co‐mimic in Mullerian mimicry rings) even if it is not itself endangered. Implications of mimicry for Conservation of the endangered smooth snake  相似文献   
674.
Abstract: Concerns about pollinator declines have grown in recent years, yet the ability to detect changes in abundance, taxonomic richness, and composition of pollinator communities is hampered severely by the lack of data over space and time. Citizen scientists may be able to extend the spatial and temporal extent of pollinator monitoring programs. We developed a citizen‐science monitoring protocol in which we trained 13 citizen scientists to observe and classify floral visitors at the resolution of orders or super families (e.g., bee, wasp, fly) and at finer resolution within bees (superfamily Apoidea) only. We evaluated the protocol by comparing data collected simultaneously at 17 sites by citizen scientists (observational data set) and by professionals (specimen‐based data set). The sites differed with respect to the presence and age of hedgerows planted to improve habitat quality for pollinators. We found significant, positive correlations among the two data sets for higher level taxonomic composition, honey bee (Apis mellifera) abundance, non‐Apis bee abundance, bee richness, and bee community similarity. Results for both data sets also showed similar trends (or lack thereof) in these metrics among sites differing in the presence and age of hedgerows. Nevertheless, citizen scientists did not observe approximately half of the bee groups collected by professional scientists at the same sites. Thus, the utility of citizen‐science observational data may be restricted to detection of community‐level changes in abundance, richness, or similarity over space and time, and citizen‐science observations may not reliably reflect the abundance or frequency of occurrence of specific pollinator species or groups.  相似文献   
675.
Nanotechnology has widespread application in agricultural, environmental and industrial sectors ranging from fabrication of molecular assemblies to microbial array chips. Despite the booming application of nanotechnology, there have been serious implications which are coming into light in the recent years within different environmental compartments, namely air, water and soil and its likely impact on the human health. Health and environmental effects of common metals and materials are well-known, however, when the metals and materials take the form of nanoparticles – consequential hazards based on shape and size are yet to be explored. The nanoparticles released from different nanomaterials used in our household and industrial commodities find their way through waste disposal routes into the wastewater treatment facilities and end up in wastewater sludge. Further escape of these nanoparticles into the effluent will contaminate the aquatic and soil environment. Hence, an understanding of the presence, behavior and impact of these nanoparticles in wastewater and wastewater sludge is necessary and timely. Despite the lack of sufficient literature, the present review attempts to link various compartmentalization aspects of the nanoparticles, their physical properties and toxicity in wastewater and wastewater sludge through simile drawn from other environmental streams.  相似文献   
676.
Commingled household waste (HW) that had a controlled composition was autoclaved at elevated pressures in the presence of saturated steam for one hour at the nominal temperature levels of 130 °C, 160 °C and 200 °C. The focus of this study was the impact of temperature/pressure on hydrolysis of organic matter during autoclaving and the extent of its hydrolysis. The pH decreased with autoclaving temperature with which it had a linear relationship, and ranged from 7.4 and 6 in floc, and 6.7 and 3.6 in steam condensate. Overall, organic matter solubilisation, as indicated by dissolved organic carbon, biological and chemical oxygen demands, and total dissolved solids, increased with temperature. Lignin did not appear to hydrolyse. Hemicellulose hydrolysed and degraded the most, followed by cellulose. The highest recoveries of hemicellulose and cellulose in solution were achieved at 160 °C, although the latter could be due to experimental error. The largest losses of hemicellulose and cellulose were recorded at 200 °C. The performance of the system in respect to hydrolysis was inferior compared to other hydrothermal systems, particularly those employing wet oxidation.  相似文献   
677.
Abstract: Results of many studies show unsustainable levels of bushmeat hunting across West/Central Africa. Nevertheless, these results are usually derived from snapshot sustainability indices in which critical parameters are often taken from the literature. Simple, more informative tools for assessing sustainability are needed. We evaluated the impact of bushmeat hunting across a range of temporal, spatial, and taxonomic scales in a comparison of different measures of sustainability. Over 15 months in 2002–2004 in and around a village close to Equatorial Guinea's Monte Alén National Park, we collected data via a village offtake survey, hunter‐camp bushmeat‐consumption diaries, hunter interviews, and following hunters during hunts. We compared 2003 data with a previous offtake survey (1998–1999) and interview reports back to 1990. In the past 14 years, average distance from the village at which hunters operated remained constant, with hunters switching back and forth between long‐established camps, although trapping effort increased. In the past 5 years, overall offtake and number of active hunters did not change substantially, although catch per unit effort (CPUE) decreased slightly. Although the proportion of the two most commonly trapped species (Cephalophus monticola and Atherurus africanus) and gun‐hunted primates increased in the offtake, species presumably less robust to trapping decreased slightly. Apparent sustainability in economic terms may be masking gradual local extirpation of more vulnerable species before and during this study. Our results suggest that changes in prey profiles and CPUE may be the most accurate indicators of actual sustainability; these indices can be monitored with simple village‐based offtake surveys and hunter interviews to improve community management of bushmeat hunting.  相似文献   
678.
Rice straw can be used as a renewable fuel for heat and power generation. It is a viable mean of replacing fossil fuels and preventing pollution caused by open burning, especially in the areas where this residual biomass is generated. Nevertheless, the thermal conversion of rice straw can cause some operating problems such as slag formation, which negatively affects thermal conversion systems. So, the main objective of this research is studying the combustion behavior of rice straw samples collected from various regions by applying thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In addition, the thermal behavior of ashes from rice straw was also analyzed in order to detect their melting points, and ash sintering was detected at different temperatures within the range between 550 and 1000 °C. Since washing rice straw with water could reduce the content of undesirable inorganic compounds related to the ash fusibility, samples of washed rice straw were analyzed under combustion conditions to investigate its differences regarding the thermal behavior of rice straw. The results showed that rice straw washing led to a significant improvement in its thermal behavior, since it reduced the ash contents and sintering formation.  相似文献   
679.
680.
Map Ta Phut Industrial Estate (MTPIE), located in Rayong province, eastern of Thailand, was developed by the state enterprise, Industrial Estate Authority of Thailand, Ministry of Industry, to serve industries that use natural gas as the main raw material development. This research presents the eco-efficiency evaluation of the petroleum and petrochemical group (PP) in the MTPIE. There are 31 factories in the PP group, which can be divided into three categories: upstream, intermediate, and downstream. The eco-efficiency values of the PP group were evaluated according to the World Business Council for Sustainable Development recommendations. The comparison of eco-efficiency values between three industrial categories in the PP group demonstrates that factories in the downstream category obtained particularly good eco-efficiency results concerning material consumption, water use, and hazardous waste generation. The eco-efficiency trends of the PP group were simply analyzed by snapshot graph. With the availability of the data on environmental indicator, the water use indicator was selected to be an example indicator for analyzing the eco-efficiency trends of the PP group. The eco-efficiency snapshot concerning the net sale and water use during the year of 2003–2005 showed that the eco-efficiency trends of the PP group in the MTPIE shifted from half eco-efficient in 2004 to fully eco-efficient in 2005. This research can provide a basic framework on eco-efficiency evaluation for the industrial sector in Thailand, which will feed into strategic development, and would enable public participation in the discussion on branch developments and contributions to national trends.  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