全文获取类型
收费全文 | 17636篇 |
免费 | 207篇 |
国内免费 | 136篇 |
专业分类
安全科学 | 484篇 |
废物处理 | 641篇 |
环保管理 | 2288篇 |
综合类 | 3655篇 |
基础理论 | 4298篇 |
环境理论 | 18篇 |
污染及防治 | 4413篇 |
评价与监测 | 1049篇 |
社会与环境 | 1006篇 |
灾害及防治 | 127篇 |
出版年
2022年 | 128篇 |
2021年 | 141篇 |
2020年 | 123篇 |
2019年 | 148篇 |
2018年 | 232篇 |
2017年 | 275篇 |
2016年 | 368篇 |
2015年 | 316篇 |
2014年 | 414篇 |
2013年 | 1425篇 |
2012年 | 508篇 |
2011年 | 701篇 |
2010年 | 565篇 |
2009年 | 619篇 |
2008年 | 719篇 |
2007年 | 747篇 |
2006年 | 686篇 |
2005年 | 563篇 |
2004年 | 525篇 |
2003年 | 541篇 |
2002年 | 477篇 |
2001年 | 594篇 |
2000年 | 460篇 |
1999年 | 269篇 |
1998年 | 216篇 |
1997年 | 206篇 |
1996年 | 224篇 |
1995年 | 234篇 |
1994年 | 237篇 |
1993年 | 217篇 |
1992年 | 225篇 |
1991年 | 218篇 |
1990年 | 213篇 |
1989年 | 186篇 |
1988年 | 159篇 |
1987年 | 138篇 |
1986年 | 165篇 |
1985年 | 166篇 |
1984年 | 174篇 |
1983年 | 169篇 |
1982年 | 166篇 |
1981年 | 178篇 |
1980年 | 157篇 |
1979年 | 154篇 |
1978年 | 114篇 |
1977年 | 128篇 |
1974年 | 118篇 |
1973年 | 98篇 |
1972年 | 115篇 |
1968年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
135.
Annika Varnäs Berit Balfors Charlotta Faith-Ell 《Journal of Cleaner Production》2009,17(13):1214-1222
Research and initiatives concerning green procurement have to a great extent focused on products. This article, however, explores the current practice, problems and opportunities of green procurement of construction contracts. In particular, the application of environmental criteria for contract awarding is targeted. The findings of the study indicate that both public and private clients in the Swedish construction industry take environmental issues into consideration in their procurements. The environmental preferences are often formulated as environmental requirements. However, environmental criteria in tender evaluation are less common and seldom affect the award decisions. The environmental evaluation criteria that do occur often relate to the contractors' capabilities of managing the environmental work in the project. 相似文献
136.
137.
Recently, integration of personality traits into a ‘pace-of-life syndrome’ (POLS) context has been advocated. To be able to understand how an individual’s behavioural, physiological and life history traits may coevolve, we need to jointly quantify these traits in order to study their covariance. Few studies have established links between personality and immunity properties of an individual. We here examined covariation of a measure of skeletal size (tarsus length), three behavioural traits (activity, handling aggression and breath rate) and two immunological traits (IgG level and haematocrit), in 592 wild caught blue tits. Many individuals (201) were tested more than once, allowing quantification of individual consistency of all traits and partition of the covariances between the traits, using a multivariate mixed model, into between individual and residual covariances. We find individual consistency of all behavioural traits, indicating that these capture aspects of blue tit adult personality and also the physiological measures are repeatable. Contrary to the POLS expectation, we find no overall significant individual level correlation structure between these traits and a factor analytical approach confirmed that between individual correlations across traits were not due to a common (POLS) factor or driven by size (tarsus length). Based on a published power study, we conclude that there is no common syndrome of individual level covariance between personality and physiological traits in wild blue tits or that the effect sizes, such a syndrome generates, are too low (r?<?0.3) to detect. Future field-based work should be designed to explore low effect sizes and strive to measure specific traits whose involvement is implicated to have large effect sizes as based on, e.g. laboratory findings. 相似文献
138.
Electrocution on overhead power structures negatively affects avian populations in diverse ecosystems worldwide, contributes to the endangerment of raptor populations in Europe and Africa, and is a major driver of legal action against electric utilities in North America. We investigated factors associated with avian electrocutions so poles that are likely to electrocute a bird can be identified and retrofitted prior to causing avian mortality. We used historical data from southern California to identify patterns of avian electrocution by voltage, month, and year to identify species most often killed by electrocution in our study area and to develop a predictive model that compared poles where an avian electrocution was known to have occurred (electrocution poles) with poles where no known electrocution occurred (comparison poles). We chose variables that could be quantified by personnel with little training in ornithology or electric systems. Electrocutions were more common at distribution voltages (≤33 kV) and during breeding seasons and were more commonly reported after a retrofitting program began. Red‐tailed Hawks (Buteo jamaicensis) (n = 265) and American Crows (Corvus brachyrhynchos) (n = 258) were the most commonly electrocuted species. In the predictive model, 4 of 14 candidate variables were required to distinguish electrocution poles from comparison poles: number of jumpers (short wires connecting energized equipment), number of primary conductors, presence of grounding, and presence of unforested unpaved areas as the dominant nearby land cover. When tested against a sample of poles not used to build the model, our model distributed poles relatively normally across electrocution‐risk values and identified the average risk as higher for electrocution poles relative to comparison poles. Our model can be used to reduce avian electrocutions through proactive identification and targeting of high‐risk poles for retrofitting. Modelo Predictivo del Riesgo de Electrocución de Aves en Líneas Eléctricas Elevadas 相似文献
139.
140.
KEN LONGENECKER YVONNE L. CHAN ROBERT J. TOONEN DAVID B. CARLON TERRY L. HUNT ALAN M. FRIEDLANDER EDWARD E. DEMARTINI 《Conservation biology》2014,28(5):1322-1330
Reef‐fish management and conservation is hindered by a lack of information on fish populations prior to large‐scale contemporary human impacts. As a result, relatively pristine sites are often used as conservation baselines for populations near sites affected by humans. This space‐for‐time approach can only be validated by sampling assemblages through time. We used archaeological remains to evaluate whether the remote, uninhabited Northwestern Hawaiian Islands (NWHI) might provide a reasonable proxy for a lightly exploited baseline in the Main Hawaiian Islands (MHI). We used molecular and morphological techniques to describe the taxonomic and size composition of the scarine parrotfish catches present in 2 archaeological assemblages from the MHI, compared metrics of these catches with modern estimates of reproductive parameters to evaluate whether catches represented by the archaeological material were consistent with sustainable fishing, and evaluated overlap between size structures represented by the archaeological material and modern survey data from the MHI and the NWHI to assess whether a space‐for‐time substitution is reasonable. The parrotfish catches represented by archaeological remains were consistent with sustainable fishing because they were dominated by large, mature individuals whose average size remained stable from prehistoric (AD approximately 1400–1700) through historic (AD 1700–1960) periods. The ancient catches were unlike populations in the MHI today. Overlap between the size structure of ancient MHI catches and modern survey data from the NWHI or the MHI was an order of magnitude greater for the NWHI comparison, a result that supports the validity of using the NWHI parrotfish data as a proxy for the MHI before accelerated, heavy human impacts in modern times. Evidencia Arqueológica de la Validez de Poblaciones de Peces en Arrecifes Sin Explotar como Objetivos de Apoderamiento para Poblaciones Actuales 相似文献