全文获取类型
收费全文 | 518篇 |
免费 | 2篇 |
专业分类
安全科学 | 44篇 |
废物处理 | 24篇 |
环保管理 | 10篇 |
综合类 | 37篇 |
基础理论 | 71篇 |
污染及防治 | 228篇 |
评价与监测 | 75篇 |
社会与环境 | 31篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2019年 | 30篇 |
2018年 | 22篇 |
2017年 | 34篇 |
2016年 | 47篇 |
2015年 | 9篇 |
2014年 | 39篇 |
2013年 | 102篇 |
2012年 | 25篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 12篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1961年 | 2篇 |
1938年 | 1篇 |
1927年 | 1篇 |
排序方式: 共有520条查询结果,搜索用时 31 毫秒
511.
The complexity of nectar: secretion and resorption dynamically regulate nectar features 总被引:2,自引:0,他引:2
In this paper, we review the phenomenon of nectar resorption, focusing on its physiological and ecological meaning. Nectar
resorption is a phenomenon that has long been known but was rarely reported until the1990s. It has more recently been demonstrated
in several species by various direct and indirect methodologies. It has generally been demonstrated in senescent flowers as
a phenomenon separate in time from, and independent of, nectar secretion. The significance of this type of resorption is generally
recognized as a resource-recovery strategy, recycling at least some materials invested in nectar production. Nevertheless,
nectar resorption can occur concomitantly with nectar secretion. Nectar production is therefore best considered as a unified
process comprising nectar secretion and resorption. The modulation of these two opposite phases allows nectar concentration
to be maintained in a range suitable for pollinators (nectar homeostasis). The mechanism of nectar resorption at the cell
level has received little attention, and its molecular basis can only be hypothesized on the basis of recent studies concerning
sugar sensing. 相似文献
512.
Ex vitro cultures of Pleurotus eryngii were carried out under controlled conditions using sterile medium composed of barley seeds. The influence of alkali and alkaline earth element salts (CsCl, KCl, NaCl, RbCl, and CaCl(2)) and tetraethylammonium chloride on incorporation of cesium, potassium, sodium, rubidium and calcium, and their distribution within fruitbodies, was examined. The results show that incorporation of cesium into fruitbodies was not suppressed by Na(+) and Rb(+) or tetraethylammonium chloride. However, it was inhibited by Ca(2+) and stimulated by high concentrations of K(+). The inhibition of cesium incorporation by Ca(2+), lack of influence of tetraethylammonium chloride and stimulation by high K(+) concentrations suggest that there may exist two pathways of passive transport of cesium in mycelium: (i) uptake mediated by a non-specific potassium channel localised in plasmalemma (similar to voltage-insensitive cation channel, VICC) followed by diffusive transport inside hyphae and (ii) extracellular transport from the medium through inter-hyphal cavities into fruitbodies. The results highlight distinctiveness of mechanisms responsible for the uptake and incorporation of cesium in mushrooms and plants. 相似文献
513.
Shawan Chowdhury Kristofer Gonzalez M. Çisel Kemahlı Aytekin Seung-Yun Baek Michał Bełcik Sandro Bertolino Sjoerd Duijns Yuqing Han Kerstin Jantke Ryosuke Katayose Mu-Ming Lin Elham Nourani Danielle Leal Ramos Marie-Morgane Rouyer William Sidemo-Holm Svetlana Vozykova Veronica Zamora-Gutierrez Tatsuya Amano 《Conservation biology》2022,36(4):e13883
English is widely recognized as the language of science, and English-language publications (ELPs) are rapidly increasing. It is often assumed that the number of non-ELPs is decreasing. This assumption contributes to the underuse of non-ELPs in conservation science, practice, and policy, especially at the international level. However, the number of conservation articles published in different languages is poorly documented. Using local and international search systems, we searched for scientific articles on biodiversity conservation published from 1980 to 2018 in English and 15 non-English languages. We compared the growth rate in publications across languages. In 12 of the 15 non-English languages, published conservation articles significantly increased every year over the past 39 years, at a rate similar to English-language articles. The other three languages showed contrasting results, depending on the search system. Since the 1990s, conservation science articles in most languages increased exponentially. The variation in the number of non-English-language articles identified among the search systems differed markedly (e.g., for simplified Chinese, 11,148 articles returned with local search system and 803 with Scopus). Google Scholar and local literature search systems returned the most articles for 11 and 4 non-English languages, respectively. However, the proportion of peer-reviewed conservation articles published in non-English languages was highest in Scopus, followed by Web of Science and local search systems, and lowest in Google Scholar. About 20% of the sampled non-English-language articles provided no title or abstract in English; thus, in theory, they were undiscoverable with English keywords. Possible reasons for this include language barriers and the need to disseminate research in countries where English is not widely spoken. Given the known biases in statistical methods and study characteristics between English- and non-English-language studies, non-English-language articles will continue to play an important role in improving the understanding of biodiversity and its conservation. 相似文献
514.
Mazur Karolina E. Borucka Aleksandra Kaczor Paulina Gądek Szymon Bogucki Rafał Mirzewiński Dariusz Kuciel Stanisław 《Journal of Polymers and the Environment》2022,30(6):2341-2354
Journal of Polymers and the Environment - In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%,... 相似文献
515.
516.
Toxicity and biodegradability of sulfonamides and products of their photocatalytic degradation in aqueous solutions 总被引:7,自引:0,他引:7
The photocatalytic degradation of sulfacetamide, sulfathiazole, sulfamethoxazole and sulfadiazine in water solutions during their illumination of UV radiation (lambda(max) 366 nm) with TiO2 catalyst was examined. The growth-inhibition effect of sulfonamides and intermediate products theirs photodegradation was investigated in aqueous solution with the green alga Chlorella vulgaris. The biodegradability of the investigated compounds was determined in the illuminated solutions and is expressed as Biochemical Oxygen Demand. It was found that all of the investigated sulfonamides in the initial solutions were resistant to biodegradation and were toxic relative to C. vulgaris. The toxicity (EC50 values) relative to C. vulgaris increased in the following order sulfacetamide, sulfathiazole, sulfamethoxazole, sulfadiazine. All of the investigated sulfonamides undergo photocatalytic degradation. The toxicity of intermediate products of the sulfonamides degradation was significantly lower than the toxicity of sulfonamides in the initial solutions and was dependent on illumination time and degradation rate. The intermediate products of photocatalysis in contrast to the initial sulfonamides, might be mineralized using biological methods. 相似文献
517.
西藏拉萨市热岛效应及其影响因子分析 总被引:3,自引:0,他引:3
采用2001年、2004年以及2007年三年的EOS/MODIS遥感信息反演的地面温度以及多年常规气象观测资料,讨论了拉萨市热岛现象及其可能影响因子。结果表明:(1)热岛强度的年、季节变化呈现逐渐增强的趋势,其中,冬季的热岛强度最强,其次是春季,秋季和夏季的热岛效应较弱;高温区基本位于城市中心或者县城所在地及其周围,低温区主要集中在各县的郊区;近年来拉萨地区的城市高温区域逐渐扩大,有些高温中心可能向某些区域偏移;遥感资料所获取的地表温度与平均气温之间存在一定的正相关性。(2)无论是年变化,还是季节变化,热岛强度都与风速呈正相关,与日照时数呈负相关,与蒸发量的相关在夏季和冬季分别呈正相关、负相关的相反状况;地表温度与植被分布具有较好的负相关关系,即在城区存在较高的地表温度分布和较小的NDVI,过渡到郊区具有温度减小、NDVI增加的特征;随着城市化进程的加剧,建筑面积不断扩大,人类活动明显增加,排放至大气的人为热增加,这些因素都可能导致热岛强度的增强。 相似文献
518.
拉萨市大气污染分布特征及气象影响因子分析 总被引:3,自引:1,他引:3
以2001~2006年拉萨市的空气环境质量自动监测结果为基础数据,阐明拉萨市区主要大气污染物SO2、NO2、PM10的逐日变化、季节变化以及年变化特征.在此基础上,分析了大气污染物浓度与气象条件的关系.结果表明,除NO2日夜差别不大之外,SO2与PM10质量浓度分别存在典型的单峰、双峰变化;各污染物质量浓度具有冬强夏弱的季节变化规律;就年平均而言,SO2浓度增加,PM10浓度降低,NO2浓度变化不显著,各污染物有明显的突变现象.大多数气象要素与污染物浓度具有较好的负相关,即满足降水量增加、温度升高、相对湿度增大会导致污染物浓度减小的规律,气象要素量级与大气污染天数多少也存在密切关系. 相似文献
519.
William J. Smith Claudio S. Quilodrán Michał T. Jezierski Ashley T. Sendell-Price Sonya M. Clegg 《Conservation biology》2022,36(3):e13867
Domestic animals have immense economic, cultural, and practical value and have played pivotal roles in the development of human civilization. Many domesticates have, among their wild relatives, undomesticated forms representative of their ancestors. Resurgent interest in these ancestral forms has highlighted the unclear genetic status of many, and some are threatened with extinction by hybridization with domestic conspecifics. We considered the contemporary status of these ancestral forms relative to their scientific, practical, and ecological importance; the varied impacts of wild–domestic hybridization; and the challenges and potential resolutions involved in conservation efforts. Identifying and conserving ancestral forms, particularly with respect to disentangling patterns of gene flow from domesticates, is complex because of the lack of available genomic and phenotypic baselines. Comparative behavioral, ecological, and genetic studies of ancestral-type, feral, and domestic animals should be prioritized to establish the contemporary status of the former. Such baseline information will be fundamental in ensuring successful conservation efforts. 相似文献
520.
Przydatek Grzegorz Budzik Grzegorz Janik Małgorzata 《Environmental science and pollution research international》2022,29(21):31467-31475
Environmental Science and Pollution Research - This paper discusses interactions between the generation, collection and recovery of used tyres while considering an indicator of their mass... 相似文献