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   697篇
  免费   47篇
  国内免费   194篇
安全科学   30篇
废物处理   18篇
环保管理   122篇
综合类   347篇
基础理论   195篇
环境理论   1篇
污染及防治   120篇
评价与监测   51篇
社会与环境   53篇
灾害及防治   1篇
  2024年   2篇
  2023年   9篇
  2022年   19篇
  2021年   30篇
  2020年   22篇
  2019年   14篇
  2018年   23篇
  2017年   27篇
  2016年   31篇
  2015年   39篇
  2014年   41篇
  2013年   81篇
  2012年   45篇
  2011年   77篇
  2010年   54篇
  2009年   44篇
  2008年   31篇
  2007年   62篇
  2006年   55篇
  2005年   48篇
  2004年   21篇
  2003年   33篇
  2002年   13篇
  2001年   11篇
  2000年   16篇
  1999年   10篇
  1998年   15篇
  1997年   4篇
  1996年   8篇
  1995年   11篇
  1994年   7篇
  1993年   6篇
  1992年   7篇
  1991年   2篇
  1990年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
  1978年   2篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1971年   4篇
排序方式: 共有938条查询结果,搜索用时 312 毫秒
261.
This study evaluated the effects of levels of automation (LOAs) decisions in advanced control rooms of the modernized nuclear power plants. Following advancements in design of digitalized human–system interfaces (HSIs), the roles of human operators have changed significantly. Negative performance and safety consequences may occur as a result of these changes. These problems are viewed as the out-of-the-loop (OOTL) performance problems. This study conducted an experiment to compare the effects of different LOAs under different operating procedures on operating performance. Experimental results indicated that blended decision-making (level 6 LOA) generates the lowest mental workload. Furthermore, the pattern of SA observed in this study is found better SA at intermediate LOA and poorer SA at low level of automation and full automation. Subjective rating results suggest that LOAs distribute the roles of option generation, and selection between human and/or computer servers which significantly impacts automated system performance. This study provides a direction for the HSI designers in nuclear power plants (NPPs). Additionally, based on results obtained by this study, the user interfaces of PCTRAN system and the alarm reset system should be improved to ensure safe operation of NPPs.  相似文献   
262.
Certain plants have demonstrated the capability to take up and accumulate metals, thus offering the potential to remediate metal-contaminated water and sediment. Several aquatic species have further been identified which can take up metal and metal oxide engineered nanoparticles (ENPs). It is important to evaluate if aquatic plants exhibiting potential for metal phytoremediation can be applied to remediation of metallic ENPs. Understanding the interactions between ENPs and aquatic plants, and evaluating possible influences on metal uptake and phytoremediation processes is therefore essential. This review article will address the feasibility of green plants for treatment of ENP-affected aquatic ecosystems. Discussion will include common types of ENPs in current use; transformations of ENPs in aquatic systems; the importance of microorganisms in supporting plant growth; ENP entry into the plant; the influence of microorganisms in promoting plant uptake; and recent findings in phytoremediation of ENP-affected water, including applications to constructed wetlands.  相似文献   
263.
A comparison of two Siberian moth populations from the Altai Republic (feeding on Siberian fir) and the Tyva Republic (feeding on Siberian larch) has revealed no differences between them with respect to ecophysiological parameters of larval growth and feeding on needles of the same conifer species under laboratory conditions. The index of appropriateness of food plants for the larvae from both populations decreases in the series larch > fir > spruce > pine. The age-related dynamics of parameters characterizing the feeding and growth of larvae are independent of the population to which the insects belong.  相似文献   
264.
The possibility of finding new medicines from natural sources is one of the more commonly cited reasons for preserving biodiversity, and employing indigenous knowledge of traditional healing remedies greatly increases the likelihood of discovering these hidden medicinal compounds. The main difficulties in using natural products as a source for pharmaceutical lead compounds involve separating the plethora of compounds from the original extract, as well as the gamble of time and money invested in an activity that may not yield a novel compound. However, while these difficulties exist, the potential of natural products still far outweighs the limitations of the simple structures and known modes of action of synthetic lead compounds. As such, the production of novel medicines, particularly for cancer and human immunodeficiency virus (HIV) treatments as well as the inhibition of antibiotic-resistant bacteria, now requires the utilization of natural products. This paper provides a review of the current methods used in elucidating pharmaceutical lead compounds from natural sources, focusing on plant samples in particular.  相似文献   
265.
The possibility of using phytoremediation with weed plant species in Thailand to remove chromium (Cr) from soil was investigated. Six plant species, Cynodon dactylon, Pluchea indica, Phyllanthus reticulatus, Echinochloa colonum, Vetiveria nemoralis, and Amaranthus viridis, were chosen for their abilities to accumulate total chromium (TCr) at tanning industry sites. These plant species were studied in pots at a nursery. Cynodon dactylon and Pluchea indica provided highest TCr accumulation capacities of 152.1 and 151.8 mg/kg of plant on a dry weight basis, respectively, at a pulse hexavalent Cr [Cr(VI)] input of 100 mg Cr(VI)/kg soil. Most of the Cr uptake occurred within 30 days after the input. The TCr accumulation by Pluchea indica was observed in roots, stems, and leaves at 27%, 38%, and 35% of the TCr mass uptake, respectively, whereas 51%, 49% and 0% of the TCr mass uptake accumulated in roots, stems, and leaves of Cynodon dactylon, respectively. The results on Cr accumulation and translocation in plant tissues suggest that Cr was removed mainly via phytoaccumulation and Pluchea indica is more suitable than Cynodon dactylon for the phytoremediation of Cr contaminated soil.  相似文献   
266.
安徽省蓼族植物资源的开发利用   总被引:3,自引:0,他引:3  
安徽省有蓼族植物43种6变种,分布广、用途多、蕴藏量大,其中42种可供药用,29种可作观赏植物,10种可在农业生产上作农药,具有良好的开发利用前景。  相似文献   
267.
经调查鉴定,重庆獐牙菜属药用植物有9种,其中西南獐牙菜、北方獐牙菜为重庆分布新记录。重点介绍了它们的医疗用途、地理分布、资源现状及其开发前景,为正确鉴别使用,编制了其分种检索表。  相似文献   
268.
重庆市基于排放绩效的火电行业二氧化硫总量控制研究   总被引:1,自引:0,他引:1  
唐燕秋  陈佳  熊强  唐敏  雷波 《四川环境》2006,25(4):22-24
本文介绍了排放绩效及排放绩效方法在火电行业二氧化硫总量控制方面的应用,并对重庆市火电机组及其二氧化硫排放状况进行了全面调查,根据重庆市二氧化硫污染防治的需要制定了各时段机组“十一五”期间的排放绩效控制标准,利用排放绩效方法测算了重庆市火电行业二氧化硫总量控制目标,提出了总量配额分配方法。  相似文献   
269.
The effects of probable climate change—an increase in atmospheric CO2(by two times), air temperature, precipitation—on CO2exchange and temperature dependence of net photosynthesis in the larch and Siberian stone pine undergrowth formed in the light larch forests of West Siberia were studied in chambers with an artificial climate. The change of the aforementioned ecological factors caused an increase in the temperature optima of photosynthesis and the range of optimum temperatures (in the case of Siberian stone pine, to a slightly greater degree). Therefore, the ranges of both species may broaden, and the Siberian stone pine can expand to the north, displacing larch tree stands.  相似文献   
270.
运用隔离生态水区(mesocosm)的手法模拟再现小型封闭水体环境,对水培植物过滤法(HBFM)去除藻类的特性进行了研究.结果表明,藻类去除率平均可达61.1%,对有毒藻类Microcystis sp.的去除效果尤其明显.通过建立生态数学模型并进行计算机模拟,得出在循环比(日处理水量/封闭水体容量)为 0.2 的条件下,应用 HBFM 在 45d 内就可以使封闭水体的 Chl.a 浓度从 100μg/L 降低到 10μg/L .  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