全文获取类型
收费全文 | 29224篇 |
免费 | 280篇 |
国内免费 | 243篇 |
专业分类
安全科学 | 667篇 |
废物处理 | 1171篇 |
环保管理 | 3454篇 |
综合类 | 5986篇 |
基础理论 | 7316篇 |
环境理论 | 10篇 |
污染及防治 | 7306篇 |
评价与监测 | 1905篇 |
社会与环境 | 1796篇 |
灾害及防治 | 136篇 |
出版年
2022年 | 218篇 |
2021年 | 208篇 |
2019年 | 202篇 |
2018年 | 373篇 |
2017年 | 399篇 |
2016年 | 596篇 |
2015年 | 472篇 |
2014年 | 722篇 |
2013年 | 2145篇 |
2012年 | 837篇 |
2011年 | 1188篇 |
2010年 | 998篇 |
2009年 | 1035篇 |
2008年 | 1199篇 |
2007年 | 1267篇 |
2006年 | 1099篇 |
2005年 | 926篇 |
2004年 | 939篇 |
2003年 | 935篇 |
2002年 | 885篇 |
2001年 | 1132篇 |
2000年 | 772篇 |
1999年 | 511篇 |
1998年 | 331篇 |
1997年 | 375篇 |
1996年 | 387篇 |
1995年 | 417篇 |
1994年 | 419篇 |
1993年 | 362篇 |
1992年 | 371篇 |
1991年 | 361篇 |
1990年 | 363篇 |
1989年 | 340篇 |
1988年 | 294篇 |
1987年 | 287篇 |
1986年 | 279篇 |
1985年 | 281篇 |
1984年 | 296篇 |
1983年 | 288篇 |
1982年 | 279篇 |
1981年 | 248篇 |
1980年 | 232篇 |
1979年 | 235篇 |
1978年 | 211篇 |
1977年 | 212篇 |
1976年 | 169篇 |
1975年 | 177篇 |
1974年 | 194篇 |
1973年 | 179篇 |
1972年 | 168篇 |
排序方式: 共有10000条查询结果,搜索用时 609 毫秒
911.
Jesús M. Avilés Deseada Parejo Tomás Pérez-Contreras Carlos Navarro Juan J. Soler 《Die Naturwissenschaften》2010,97(2):181-186
A considerable number of bird species carry feathers to their nests. Feathers’ presence in the nests has traditionally been
explained by their insulating properties. Recently, however, it has been suggested that feathers carried to the nests by females
of the spotted starling (Sturnus unicolor L.) could have an ornamental function based on their ultraviolet (300–400 nm) and human-visible longer wavelength (400–700 nm)
coloration. In our population, 95.7% of feathers found inside next-boxes occupied by nesting starlings were rock dove fly
feathers. Of these feathers, 82.7% were naturally positioned with their reverse side oriented toward the entrance hole and
42.4% of all found feathers were situated within the nest-cup. Here we experimentally assess the signaling function of ultraviolet
coloration of feathers in nests of spotless starlings by providing nests with a number of pigeon flight feathers that were
respectively treated on their obverse, reverse, both, or neither side with a UV blocker. Starlings placed 42.5% of the experimental
feathers in the nest-cup irrespective of the UV block treatment. Orientation of feathers toward the entrance hole was not
related with their ultraviolet radiation. However, feathers placed within the nest-cup were more likely found with their reverse
side oriented toward the entrance hole confirming our correlative findings. These results suggest a minor role of ultraviolet
coloration on feather location by spotless starlings. 相似文献
912.
913.
914.
915.
CARLOS CARROLL JOHN A. VUCETICH MICHAEL P. NELSON DANIEL J. ROHLF MICHAEL K. PHILLIPS 《Conservation biology》2010,24(2):395-403
Abstract: The U.S. Endangered Species Act (ESA) defines an endangered species as one “at risk of extinction throughout all or a significant portion of its range.” The prevailing interpretation of this phrase, which focuses exclusively on the overall viability of listed species without regard to their geographic distribution, has led to development of listing and recovery criteria with fundamental conceptual, legal, and practical shortcomings. The ESA's concept of endangerment is broader than the biological concept of extinction risk in that the “esthetic, ecological, educational, historical, recreational, and scientific” values provided by species are not necessarily furthered by a species mere existence, but rather by a species presence across much of its former range. The concept of “significant portion of range” thus implies an additional geographic component to recovery that may enhance viability, but also offers independent benefits that Congress intended the act to achieve. Although the ESA differs from other major endangered‐species protection laws because it acknowledges the distinct contribution of geography to recovery, it resembles the “representation, resiliency, and redundancy” conservation‐planning framework commonly referenced in recovery plans. To address representation, listing and recovery standards should consider not only what proportion of its former range a species inhabits, but the types of habitats a species occupies and the ecological role it plays there. Recovery planning for formerly widely distributed species (e.g., the gray wolf [Canis lupus]) exemplifies how the geographic component implicit in the ESA's definition of endangerment should be considered in determining recovery goals through identification of ecologically significant types or niche variation within the extent of listed species, subspecies, or “distinct population segments.” By linking listing and recovery standards to niche and ecosystem concepts, the concept of ecologically significant type offers a scientific framework that promotes more coherent dialogue concerning the societal decisions surrounding recovery of endangered species. 相似文献
916.
Donald G. Gillette 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1238-1243
Whereas most estimates of material damage are based on industrial surveys, the estimates produced in this study were derived from material damage experiments and ambient air quality data. Air quality data on SO2 were obtained from 200 or more monitoring sites primarily located in heavily populated or polluted areas. Material threshold damage function data were then compared with SO2 levels, and an estimate of losses, as reflected in increased maintenance and replacement costs, was determined. Estimates of the total stock of various materials in use were derived from census and industry data and allocated geographically according to population. A substantial decrease in the ambient SO2 levels, particularly in larger urban areas, has occurred during the past five years. From 1968 to 1972, the estimated amount of material damage from SO2 in the U. S. decreased from $900 million/yr to less than $100 million. During this period, the estimated percentage of man made materials exposed to SO2 levels exceeding the proposed secondary annual average standard (60 μg/m3) and primary annual average standard (80 μg/m3) in the U. S. fell respectively, from 20% to less than 5% and from more than 10% to less than 1%. Most of the present loss is attributed to corrosion damage of metallic surfaces that are normally exposed to the ambient environment. 相似文献
917.
918.
Mountain ecosystems are considered vulnerable to early impacts of climate change. Whether and how local residents of these areas perceive these changes, however, remain under-studied questions. By conducting a household survey in the Khumbu region of Nepal, this study assessed local residents’ experience-based perception of changes in climate trends and patterns, perceived risk, and attitudes towards climate issues. Multivariate cluster analysis based on residents’ climate change beliefs revealed three segments: “Cautious,” “Disengaged,” and “Alarmed.” A comparison of these segments along key psychosocial constructs of Protection Motivation Theory (PMT) revealed significant inter-segment differences in residents’ perception of severity, vulnerability, response efficacy, self-efficacy, and response cost associated with engaging in mitigating behavior. Results shed light on how residents of high elevation areas that are considered to be exposed to early impacts of climate change perceive the risk and intend to respond. These findings could also assist stakeholders working in other similar mountain ecosystems in understanding vulnerability and in working towards climate readiness.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01369-x) contains supplementary material, which is available to authorized users. 相似文献
919.
Gómez-Tolosa María Rivera-Velázquez Gustavo Rioja-Paradela Tamara M. Mendoza-Cuenca Luis F. Tejeda-Cruz César López Sergio 《Environmental science and pollution research international》2021,28(2):1381-1396
Environmental Science and Pollution Research - The order Odonata has been regularly used as an indicator of the ecosystem’s condition. The objective of this review was to analyze the... 相似文献
920.
Aliste Marina Garrido Isabel Pérez-Lucas Gabriel Flores Pilar Hellín Pilar Navarro Simón Fenoll José 《Environmental science and pollution research international》2021,28(19):23849-23858
Environmental Science and Pollution Research - In this study, the photocatalytic degradation of four fungicides, myclobutanil, penconazole and difenoconazole (triazole compounds) and boscalid... 相似文献