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91.
92.
Steven Kragten Krijn B. Trimbos Geert R. de Snoo 《Agriculture, ecosystems & environment》2008,126(3-4):163-167
The aim of this study was to analyse the effects of differences in cropping pattern between organic and conventional arable farms on the breeding activity of skylarks and to assess the effects of arable crop management on skylark nest survival. Skylark nest density was seven times higher on organic farms than on conventional farms (0.63 vs. 0.09 nest per 10 ha). Skylarks showed a strong preference for spring cereals, lucerne and grass leys, all of which were mainly or exclusively grown on organic farms. On organic farms nests were initiated during the entire breeding season, but on conventional farms no nesting activity was found during the peak of the season (early May to early June). On organic farms 27% of all nests was successful. Increasing the availability of suitable breeding habitat during the peak of the breeding season on conventional farms might provide one means of enhancing breeding skylark populations. On organic farms, crop management should focus on reducing nest loss due to farming operations. 相似文献
93.
Sex mosaics in a male dimorphic ant Cardiocondyla kagutsuchi 总被引:1,自引:1,他引:0
Gynandromorphy, or the development of organisms with a combination of male and female morphological features, is common in
Hymenoptera. The underlying mechanism is likely associated with the sex-determination system, and studying this phenomenon
should lead to a deeper understanding of both embryonic development and sex determination. The reproductive capabilities of
gynandromorphs (hereafter, sex mosaics) remain unclear. We studied gynandromorphy in the Malaysian ant Cardiocondyla kagutsuchi, which has sex mosaics of queens (gynandromorphs; mosaic of queens and winged male) and workers (ergatandromorphs; mosaic
of worker and wingless ergatoid male). These sex mosaics were classified into seven morphological categories. Most individuals
had more male than female body areas. Behavioral observations revealed that sex mosaics behave more in accordance with the
“sex” of their brain than that of the reproductive organs (gaster). Relative DNA quantities showed that both female and male
regions contained haploid and diploid nuclei, irrespective of their phenotypic appearance, indicating that external appearance
did not reflect internal tissues. Nearly one third of the adults were sex mosaics and they were not infected with Wolbachia. Our results suggest that the production of sex mosaics in this species does not pose a substantial cost to colonies and
that the underlying causes are therefore not strongly selected against. 相似文献
94.
Polistes wasps engage in many behavioral interactions. Although there has been debate over the meaning of these interactions, these
stereotypical behaviors can be used to determine a colony’s linear dominance hierarchy. Due to the implicit relationship between
behavioral and reproductive dominance, behavioral interactions are commonly used to distinguish the reproductively dominant
alpha foundress from the beta foundress. It has been suggested that in order to maintain reproductive control, the alpha foundress
is forced to remain at a physiologically constrained activity limit. This, in turn, may allow aggressive interactions to be
used as determinants influencing reproductive partitioning between cooperating individuals. Energetic costs can place important
limitations on behavior, but the energetic cost of the interactions has not previously been measured. To address this, we
measured the CO2 production of 19 non-nestmate pairs displaying interactive and noninteractive behavior. The rate of energy used during interaction
behavior was positively associated with published rankings of aggression. However, our results indicate that interactions
are not very energetically costly in Polistes, particularly when compared to the likely cost of foraging. These data suggest that maintaining reproductive dominance is
not very energetically expensive for the dominant and that the dominant foundress expends energy at a lower rate than the
subordinate foundress.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
95.
Pollution in urban zoos arises from diffuse and small point sources. However, its control has received little attention in past decades. Online and ofttine modes of ecological engineering technology were designed to control pollution from small point and diffuse sources in Wuhan City Zoo, China. Their characteristics and performances were investigated in sixteen runoff events from 2003 to 2005. The results showed that the two modes both improved runoff water quality and had high retention rates for water and pollutants. In the outflows, the event mean concentrations (EMCs) of total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were reduced by 88%, 59%, 46% and 71% for the online mode, and those were 77%, 42%, 50% and 66% for the ofttine mode. The annual retention rates of pollutant loads for the online mode were 94.9%-98.5% in the three study years; those for the ofitine mode were 70.5%-86.4%. Based on calculation, the online mode was able to store the runoff of 66.7 mm rainfall completely, and the ofttine mode could store that of 31.3 mm rainfall. In addition, the online mode can provide an effective way for rainwater utilization and good habitats for aquatic wildlives, and has an excellent aesthetics value for recreationsal pastimes. The ofiline mode can save land resources and may be an effective and economical measure for diffuse pollution control in urban areas. 相似文献
96.
In 2006 the Massachusetts Toxics Use Reduction Institute conducted a study to determine if states could identify safer alternatives to five chemicals of concern. The chemicals investigated included di (2-ethylhexyl) phthalate (DEHP), formaldehyde, hexavalent chromium, lead and perchloroethylene. First, the Institute developed a methodology for assessing alternatives to these five chemicals that allowed it to quickly determine priority uses and alternatives to assess and to research the pertinent decision criteria, which included performance, technical, financial environmental and human health parameters. The methodology included important feedback from stakeholders in the state, which helped to focus and enhance the value of the work. Second, the Institute implemented the methodology over a ten month period. Based on the activities conducted by the Institute, safer alternatives were identified for each of the priority uses associated with the five chemicals studied. This report summarizes the methodology employed and provides examples of the results for one of the five chemicals, namely DEHP. The experience of the Institute and the information contained in this report indicates that alternatives assessment was a useful approach to organizing and evaluating information about chemicals and alternatives. 相似文献
97.
阿特拉津可对雄性脊椎动物生殖系统造成不良影响,但其中分子机制尚不明了。本文作者将非洲爪蟾(Xenopus laevis)暴露于100 ppb的阿特拉津120 d,利用同位素标记相对和绝对定量(iTRAQ)技术检测了非洲爪蟾睾丸和卵巢中蛋白图谱的变化,结果显示100 ppb阿特拉津可影响爪蟾发育,延迟和阻碍雄性细精管的形成。组学分析显示,睾丸中143种以及卵巢中121种蛋白均表达异常,这些蛋白与细胞凋亡、细胞间紧密连接以及代谢途径相关。
精选自Xiuping Chen, Jiamei Wang, Haojun Zhu, Jiatong Ding and Yufa Peng. Proteomics analysis of Xenopus laevis gonad tissue following chronic exposure to atrazine. Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2980
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2980/full 相似文献
98.
刘艳军 《中国安全生产科学技术》2013,9(4):176-179
从安全生产经济政策的一般理论、内涵和特点出发,给出了安全生产经济政策的定义,系统分析了构成安全生产经济政策的层次和不同模式,对安全生产经济政策相关理论进行初步探讨,并结合我国现行的安全生产经济政策对其进行分类,为深入研究安全生产经济政策措施并分析其效果奠定理论基础 相似文献
99.
100.
海上钻完井作业面临海洋环境恶劣、浅层地质灾害等复杂工况,极易发生油气泄漏、井喷等事故。为有效预防海上钻完井作业事故,提出基于瑞士奶酪模型的安全屏障模型。采用事故树和故障模式及影响分析相结合的方法,分析作业过程风险。该模型根据挪威标准D-010,建立完井作业关井阶段的物理安全屏障和安全屏障控制原理图,在此基础上构建油气泄漏事故树和失效模式与影响分析表,找出关井阶段可能的油气泄漏途径。通过对重要度计算和风险优先度值排序确定作业过程中最薄弱的安全屏障和关键故障模式。结果表明,作业过程中最薄弱的安全屏障是采油树、油管和地面控制井下安全阀(SCSSV),采油树腐蚀、密封失效、油管接头密封失效和SCSSV开关故障是影响作业过程的关键故障模式。 相似文献