全文获取类型
收费全文 | 29776篇 |
免费 | 343篇 |
国内免费 | 360篇 |
专业分类
安全科学 | 845篇 |
废物处理 | 1085篇 |
环保管理 | 4048篇 |
综合类 | 4863篇 |
基础理论 | 8621篇 |
环境理论 | 21篇 |
污染及防治 | 7788篇 |
评价与监测 | 1753篇 |
社会与环境 | 1250篇 |
灾害及防治 | 205篇 |
出版年
2022年 | 191篇 |
2021年 | 199篇 |
2019年 | 234篇 |
2018年 | 406篇 |
2017年 | 393篇 |
2016年 | 570篇 |
2015年 | 512篇 |
2014年 | 698篇 |
2013年 | 2158篇 |
2012年 | 859篇 |
2011年 | 1263篇 |
2010年 | 1053篇 |
2009年 | 1050篇 |
2008年 | 1268篇 |
2007年 | 1340篇 |
2006年 | 1198篇 |
2005年 | 1008篇 |
2004年 | 1017篇 |
2003年 | 951篇 |
2002年 | 939篇 |
2001年 | 1251篇 |
2000年 | 869篇 |
1999年 | 557篇 |
1998年 | 444篇 |
1997年 | 452篇 |
1996年 | 459篇 |
1995年 | 490篇 |
1994年 | 449篇 |
1993年 | 398篇 |
1992年 | 417篇 |
1991年 | 377篇 |
1990年 | 378篇 |
1989年 | 412篇 |
1988年 | 349篇 |
1987年 | 300篇 |
1986年 | 276篇 |
1985年 | 306篇 |
1984年 | 286篇 |
1983年 | 321篇 |
1982年 | 323篇 |
1981年 | 271篇 |
1980年 | 243篇 |
1979年 | 269篇 |
1978年 | 229篇 |
1977年 | 195篇 |
1976年 | 200篇 |
1975年 | 192篇 |
1974年 | 172篇 |
1973年 | 171篇 |
1972年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
<正>Arsenic(As)is a well-recognized toxicant and carcinogen.Chronic exposure to inorganic arsenic causes a range of human cancers(e.g.,skin,bladder,and lung)and increases the risk of developing diabetes,hypertension,and cardiovascular and neurological diseases.The prevalence of arsenic species and the severity of their health effects continue to drive and demand for extensive research(Carlin et al.,2016). 相似文献
852.
Jacqueline T. Bangm Jessica L. Reiner Hannes Both Theresa M. Cantu Marco A. Gouws Matthew P. Guillette Jeremy P. Koelmel Wilmien J. Luus-Powell Jan Myburgh Olivia Rynders Joseph R. Sar Willem J. Smit John A. Bowden 《环境科学学报(英文版)》2017,29(11):59-67
This study examined concentrations of 15 perfluoroalkyl acids (PFAAs) in tissues from male Mozambique tilapia (Oreochromis mossambicus) collected at Loskop Dam, Mpumalanga, South Africa in 2014 and 2016. Nine of the 15 PFAAs were detected frequently and were included in statistical analysis and included two of the most commonly known PFAAs, perfluorooctanesulfonic acid (PFOS) (median, 41.6 ng/g) and perfluorooctanoic acid (PFOA) (median, 0.0825 ng/g). Of the tissues measured, plasma (2016 and 2014 median, 22.2 ng/g) contained the highest PFAA burden followed by (in descending order): liver (median, 11.6 ng/g), kidney (median, 9.04 ng/g), spleen (median, 5.92 ng/g), adipose (median, 2.54 ng/g), and muscle (median, 1.11 ng/g). Loskop Dam tilapia have been affected by an inflammatory disease of the adipose tissue known as pansteatitis, so this study also aimed to investigate relationships between PFAA tissue concentrations and incidence of pansteatitis or fish health status. Results revealed that healthy tilapia exhibited an overall higher (p-value < 0.05) PFAA burden than pansteatitis-affected tilapia across all tissues. Further analysis showed that organs previously noted in the literature to contain the highest PFAA concentrations, such as kidney, liver, and plasma, were the organs driving the difference in PFAA burden between the two tilapia groups. Care must be taken in the interpretations we draw from not only the results of our study, but also other PFAA measurements made on populations (human and wildlife alike) under differing health status. 相似文献
853.
总结了实测法、公式法、模型法等国内外石化行业有机液体储罐VOCs排放估算方法的主要特点和适用范围;运用公式法估算国内某石化企业典型油品储罐的VOCs排放量;分析了在我国直接套用美国环保署(EPA)开发的TANKS模型存在的问题;根据估算方法的实际应用研究,就美国AP-42源强手册第五版第七章(chapter 7:Liquid storage tank)中评价公式的"本土化"提出相关的建议。 相似文献
854.
855.
Leena Maunula M. Rönnqvist R. Åberg J. Lunden M. Nevas 《Food and environmental virology》2017,9(3):358-359
856.
In this Concepts & Synthesis paper, we expand the definition of chronodisruption in humans by proposing that it can be operationalized as the split nexus of internal and external times. With this premise, we suggest how chronotype may be used as a temporal marker (chronomarker) of exposure to chronodisruption in studies of cancer, and beyond, offer cancer risk predictions for observational research on the basis of a chronotype-related hypothesis and corollary, and point to first empirical data in humans. In an a priori way, we examine possible outcomes and perspectives for preventive measures following from our rationale and the suggested chronobiology-driven studies and close with overall advances of chronodisruption research. 相似文献
857.
Christopher D. Pull William O. H. Hughes Mark J. F. Brown 《Die Naturwissenschaften》2013,100(12):1125-1136
Pathogens exert a strong selection pressure on organisms to evolve effective immune defences. In addition to individual immunity, social organisms can act cooperatively to produce collective defences. In many ant species, queens have the option to found a colony alone or in groups with other, often unrelated, conspecifics. These associations are transient, usually lasting only as long as each queen benefits from the presence of others. In fact, once the first workers emerge, queens fight to the death for dominance. One potential advantage of co-founding may be that queens benefit from collective disease defences, such as mutual grooming, that act against common soil pathogens. We test this hypothesis by exposing single and co-founding queens to a fungal parasite, in order to assess whether queens in co-founding associations have improved survival. Surprisingly, co-foundresses exposed to the entomopathogenic fungus Metarhizium did not engage in cooperative disease defences, and consequently, we find no direct benefit of multiple queens on survival. However, an indirect benefit was observed, with parasite-exposed queens producing more brood when they co-founded, than when they were alone. We suggest this is due to a trade-off between reproduction and immunity. Additionally, we report an extraordinary ability of the queens to tolerate an infection for long periods after parasite exposure. Our study suggests that there are no social immunity benefits for co-founding ant queens, but that in parasite-rich environments, the presence of additional queens may nevertheless improve the chances of colony founding success. 相似文献
858.
基于安全仪表系统共因失效机理的定性分析,在单一冲击下的RPS模型基础上,以泊松分布作为冲击的先验分布,建立了多冲击下考虑共因失效的安全仪表系统可靠性模型;采用基于专家经验和估计的方法,对模型参数进行估计;并通过定量分析确定出影响系统共因失效的最大冲击因子,为降低系统共因失效对可靠性的影响提供辅助决策支持。将改进的多冲击RPS模型的可靠性分析结果与β模型和PDS模型进行比较,验证了该模型的工程准确性。 相似文献
859.
M. M. P. B. Fuentes M. R. Fish J. A. Maynard 《Mitigation and Adaptation Strategies for Global Change》2012,17(1):51-63
Climate change poses a serious threat to sea turtles (Cheloniidae) as their terrestrial reproductive phase is only successful
within a limited range of environmental and physical conditions. These conditions are likely to become less optimal as climate
change progresses. To date, management and conservation of sea turtles has focused almost entirely on non-climatic stressors,
due at least in part to practitioners not knowing what strategies to take and the feasibility and risks of potential strategies.
To aid the management of sea turtles in a changing environment, we identified management strategies via a focus workshop and
surveys to mitigate the impacts of climate change to the terrestrial reproductive phase of sea turtles. The effectiveness,
ecological risks and potential social and logistical constraints associated with implementing each of the identified management
strategies is discussed. Twenty management strategies were identified; strategies varied from habitat protection to more active
and direct manipulation of nests and the nesting environment. Based on our results, we suggest a three-pronged approach to
sea turtle conservation in light of climate change, where managers and researchers should: 1) enhance sea turtle resilience
to climate change by mitigating other threats; 2) prioritise implementing the ‘no regret’ and ‘reversible’ management strategies
identified here; and 3) fill the knowledge gaps identified to aid the trial and implementation of the potential strategies identified here. By combining these three approaches our collective toolkit of sea turtle management strategies
will expand, giving us an array of viable approaches to implement as climate change impacts become more extreme. 相似文献
860.
Dimensional analysis and scaling in mechanical mixing for fabrication of metal matrix nanocomposites
S. García-Rodríguez N. Alba-Baena N.M. Rudolph J. Wellekoetter X.C. Li T.A. Osswald 《Journal of Manufacturing Processes》2012,14(3):388-392
For a successful enhancement of mechanical properties of metal matrix nanocomposites, a homogeneous nanoparticle dispersion and distribution in the solidified metal is required. Mechanical mixing can be used for initial break-up of agglomerates, and its study can be simplified with dimensional analysis. Using this technique, mixing time and vortex height were assessed while varying fluid properties, impeller angle, and angular speed. Three relevant dimensionless numbers were recognized: the Reynolds (Re), Froude and Galilei (Ga) numbers. Based on blade and impeller shaft angles, a modified Froude number (Fr*) was defined. These parameters were calculated experimentally, varying angular speed from 200 to 1000 rpm for three different impeller angles: 0°, 15° and 30°. This procedure was performed with three fluids: water, and two aqueous glycerin solutions (25% and 50% by volume). Digital images were taken and processed to measure vortex height. Mixing time was measured for water at 0° impeller angle, angular speed ranging from 200 to 1200 rpm. Results showed an optimal dimensionless mixing time with respect to Re. A linear relationship was found between dimensionless vortex height and Fr*. The first had a second order polynomial relationship with the product ReFr*, regardless of impeller angle. This relationship, together with the Ga, specific for each fluid, allows scaling the results to other fluids such as molten pure aluminum. This study allows experimenting in simpler systems that involve transparent fluids, room temperature and low cost, to then elaborate a prediction of vortex height in fluids where measurements are difficult and costly, such as molten metals. 相似文献