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   407篇
  免费   16篇
  国内免费   5篇
安全科学   12篇
废物处理   22篇
环保管理   106篇
综合类   46篇
基础理论   129篇
污染及防治   67篇
评价与监测   20篇
社会与环境   22篇
灾害及防治   4篇
  2022年   5篇
  2021年   6篇
  2020年   6篇
  2019年   4篇
  2018年   9篇
  2017年   15篇
  2016年   15篇
  2015年   17篇
  2014年   7篇
  2013年   34篇
  2012年   18篇
  2011年   23篇
  2010年   11篇
  2009年   13篇
  2008年   20篇
  2007年   20篇
  2006年   14篇
  2005年   22篇
  2004年   8篇
  2003年   10篇
  2002年   11篇
  2001年   11篇
  2000年   9篇
  1999年   6篇
  1998年   12篇
  1997年   2篇
  1996年   7篇
  1995年   8篇
  1994年   5篇
  1993年   5篇
  1992年   5篇
  1990年   4篇
  1989年   4篇
  1988年   3篇
  1987年   5篇
  1986年   4篇
  1985年   4篇
  1984年   5篇
  1983年   7篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1974年   4篇
  1973年   5篇
  1972年   3篇
  1944年   1篇
  1943年   1篇
排序方式: 共有428条查询结果,搜索用时 15 毫秒
81.
● A PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed. ● The property of flax fiber could be switched from hydrophobicity to hydrophilicity. ● The mechanism of the acquired UV-induced switchable wettability was discussed. ● The developed flax fiber was successfully used for multipurpose oil-water separation. The large number of oily wastewater discharges and oil spills are bringing about severe threats to environment and human health. Corresponding to this challenge, a functional PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed for efficient oil-water separation in this study. The developed flax fiber was obtained through PAA grafted polymerization and then ZnO-HDTMS nanocomposite immobilization. The as-prepared PAA-ZnO-HDTMS flax fiber was hydrophobic initially and could be switched to hydrophilic through UV irradiation. Its hydrophobicity could be easily recovered through being stored in dark environment for several days. To optimize the performance of the PAA-ZnO-HDTMS flax fiber, the effects of ZnO and HDTMS concentrations on its switchable wettability were investigated. The optimized PAA-ZnO-HDTMS flax fiber had a large water contact angle (~130°) in air and an extremely small oil contact angle (~0°) underwater initially. After UV treatment, the water contact angle was decreased to 30°, while the underwater oil contact angle was increased to more than 150°. Based on this UV-induced switchable wettability, the developed PAA-ZnO-HDTMS flax fiber was applied to remove oil from immiscible oil-water mixtures and oil-in-water emulsion with great reusability for multiple cycles. Thus, the developed flax fiber could be further fabricated into oil barrier or oil sorbent for oil-water separation, which could be an environmentally-friendly alternative in oil spill response and oily wastewater treatment.  相似文献   
82.
The genus Nyctiphanes (Malacostraca, Euphausiacea) comprises four neritic species that display antitropical geographic distribution in the Pacific (N. simplex and N. australis) and Atlantic (N. couchii and N. capensis) Oceans. We studied the origin of this distribution applying methods for phylogenetic reconstruction and molecular dating of nodes using a Bayesian MCMC analysis and the DNA sequence information contained in mtDNA 16S rDNA and cytochrome oxidase (COI). We tested hypotheses of vicariance by contrasting the time estimates of cladogenesis with the onset of the major barriers to ocean circulation. It was estimated that Nyctiphanes originated in the Pacific Ocean during the Miocene, with a lower limit of 18 miilion years ago (Mya). An Atlantic–Pacific cladogenic event (95% HPD 3.2–9.6) took place after the closure of the Tethyan Sea, suggesting that dispersal occurred from the Indo-Pacific, most likely via southern Africa. Similarly, the antitropical distribution pattern observed in the eastern Atlantic Ocean likely resulted from recent Pliocene–Pleistocene (95% HPD 1.0–4.97) northward dispersal from the southern hemisphere. Our results imply that dispersal appears to have had a significant role to play in the evolution of this group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
83.
This paper examines the use of on-board global positioning system (GPS) data recorders as a method to collect field data on the movements of solid waste collection vehicles at transfer stations. The movements of five waste collection vehicles using four different transfer facilities were compared over a period of 1 year. The spatial data were analyzed using geofences to determine the amount of time each truck spent on each of four activities: queuing for access to the weigh scale, sitting on the weigh scale, queuing for access to the tipping floor, and unloading waste. The study found that queuing delays can be identified and measured using GPS data. The average time at a facility for all trucks was 16.4min per visit, with a standard deviation of 14.3min. Time at the facility ranged between 2 and 111min per visit and the distribution of time at the facility was positively skewed. Multi-compartment vehicles (co-collection and recycling trucks) spent significantly more time at unloading facilities. There were also significant differences in the length and the location of the queues at different facilities. At one facility, the longest delays were encountered while waiting for the weigh scale, at two facilities trucks experienced delays in obtaining access to the tipping floor, while at the fourth facility no significant delays developed.  相似文献   
84.
Demographic Forecasting in Koala Conservation   总被引:1,自引:0,他引:1  
Abstract: The koala currently needs conservation intervention. There is clear evidence of decline in many populations, but the existence of other stable or expanding populations offers the possibility of a variety of creative solutions to their conservation problems. The 1998 National Koala Conservation Strategy emphasizes the need to obtain demographic information and to use this information to assess management options for koalas. We need accurate diagnoses of the status of koala populations and forecasts of their demographic future with and without particular management actions. In a qualitative fashion, this process has been undertaken many times on a local and national scale. Quantitative demographic forecasting tools are increasingly available, and koala management could benefit from their application both at the scale of individual populations and more broadly. There is already a considerable body of suitable data on the dispersal, effects of normal and catastrophic environmental variation on reproduction and survival, and on the effects of habitat change. Demographic forecasting, however, is hampered because the full suite of information is rarely available from a single population. In two Queensland populations, retrospective population viability analyses provided forecasts that were in agreement with observed population trends. Work is needed to determine whether data from one population can be applied to other populations. Models can then be developed to make projections at a multipopulation level on the basis of local population dynamics and dispersal. Certain koala populations, because of their long history of study, offer the opportunity to test demographic models retrospectively. These tests will not only aid in fine-tuning the models for koala biology and data but will also assist with the more general process of validating the models.  相似文献   
85.
Communication and advocacy approaches that influence attitudes and behaviors are key to addressing conservation problems, and the way an issue is framed can affect how people view, judge, and respond to an issue. Responses to conservation interventions can also be influenced by subtle wording changes in statements that may appeal to different values, activate social norms, influence a person's affect or mood, or trigger certain biases, each of which can differently influence the resulting engagement, attitudes, and behavior. We contend that by strategically considering how conservation communications are framed, they can be made more effective with little or no additional cost. Key framing considerations include, emphasizing things that matter to the audience, evoking helpful social norms, reducing psychological distance, leveraging useful biases, and, where practicable, testing messages. These lessons will help communicators think strategically about how to frame messages for greater effect.  相似文献   
86.
Regional Environmental Change - In this paper, we present the results of a systematic literature review of climate change vulnerability-related research conducted in Bangladesh between 1994 and...  相似文献   
87.
Objectives Support after fetal diagnosis of abnormality (SAFDA), is a facilitated shared experience group for women and their partners or support person, in Victoria, Australia, who have had a pregnancy termination for a fetal abnormality. The objective of this study was to evaluate the SAFDA-facilitated group. Methods A questionnaire-based study was undertaken between 2001 and 2005 to evaluate SAFDA. A deidentified self-completed questionnaire was given to participants at the end of each group and included questions relating to the referring professional, participants' prior expectations of the group, helpfulness of participation, preferred group format, length, and venue. In addition, there was also opportunity for participants to make general comments on their experiences of participating in SAFDA. Results A total of 85 participants (100% response) completed the questionnaire. Seventy-one participants (84%) considered it ‘very helpful’ to participate in the group. Seventy-eight participants (92%) considered that a shared-experience group was the most beneficial format. Comments written by participants affirmed that the present format of SAFDA was a highly valued opportunity to listen to and share experiences in a confidential small group. Conclusion SAFDA is a beneficial forum for women and their partners or support person to share their experiences after having had a pregnancy termination for a fetal abnormality. Further, SAFDA provides information and insights for health professionals who are considering how best to support women. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
88.
89.
90.
This paper reviews methods for exploring the differences between alternative equations in complex ecosystem models. A factorial design is proposed as a method for exposing possible interactions between equation forms in their effect on model output as well as to clarify differences between the main candidate equations. A number of display methods arising from statistical analysis are used including normal Q-Q plots, linear rank plots and interaction diagrams. The methods were illustrated using a complex ecosystem model of Lake Ontario. We found the methods effective at illustrating major differences between equations although several difficulties arose due to the complexity of the models and the diffuse nature of the data supporting model validation. Questions of the method for standardization of equation forms so that the compared equations are in some way analogous, are important. These methods are probably most useful in cases where the data are of sufficient quality to indicate not only how different equation forms affect model output but also which are to be preferred.  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