首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   969篇
  免费   11篇
  国内免费   6篇
安全科学   18篇
废物处理   61篇
环保管理   55篇
综合类   182篇
基础理论   161篇
污染及防治   334篇
评价与监测   109篇
社会与环境   60篇
灾害及防治   6篇
  2023年   14篇
  2022年   36篇
  2021年   43篇
  2020年   18篇
  2019年   18篇
  2018年   51篇
  2017年   34篇
  2016年   60篇
  2015年   49篇
  2014年   52篇
  2013年   80篇
  2012年   39篇
  2011年   67篇
  2010年   51篇
  2009年   27篇
  2008年   65篇
  2007年   53篇
  2006年   44篇
  2005年   30篇
  2004年   23篇
  2003年   27篇
  2002年   23篇
  2001年   18篇
  2000年   12篇
  1999年   3篇
  1998年   3篇
  1996年   4篇
  1995年   4篇
  1994年   8篇
  1993年   5篇
  1992年   4篇
  1990年   3篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1964年   1篇
  1962年   1篇
排序方式: 共有986条查询结果,搜索用时 15 毫秒
71.

Yearly, huge amounts of sock refuse are discarded into the environment. Socks contain many molecules, and worn ones, which are rich in smell-causing bacteria, have a strong influence on animals’ behaviors. But the impacts of sock odor on the oviposition behavior of dengue vectors are unknown. We assessed whether Aedes albopictus changes its oviposition activity in response to the presence of used socks extract (USEx) in potential breeding grounds, using choice and no-choice bioassays (NCB). When furnished even chances to oviposit in two sites holding USEx and two others containing water (control), Ae. albopictus deposited significantly less eggs in USEx than in water sites. A similar pattern of oviposition preference was also observed when there were more oviposition options in water. When there were greater oviposition opportunities in USEx sites, Ae. albopictus oviposited preferentially in water. Females laid significantly more eggs during the NCB involving water than USEx. Also, significantly more mature eggs were retained by females in the NCB with USEx than in that with water. These observations strongly suggest the presence of molecules with either repellent or deterrent activities against Ae. albopictus females and provide an impetus to advocate the integration of used socks in dengue control programs. Such applications could be a realistic end-of-life recourse to reroute this waste from landfills.

  相似文献   
72.
Mineral natural waters and spas have been used for therapeutic purposes for centuries, with Portugal being a very rich country in thermal waters and spas that are mainly distributed by northern and central regions where Beira Interior region is located. The use of thermal waters for therapeutic purposes has always been aroused a continuous interest, being dependent on physicochemical fingerprinting of this type of waters the indication for a treatment in a specific pathological condition. In the present work, besides a literature review about the physicochemical composition of the thermal waters of the Beira Interior region and its therapeutic indications, it was carried out an exhaustive multivariate analysis—principal component analysis and cluster analysis—to assess the correlation between different physicochemical parameters and the therapeutic indications claims described for these spas and thermal waters. These statistical methods used for data analysis enables classification of thermal waters compositions into different groups, regarding to the different variable selected, making possible an interpretation of variables affecting water compositions. Actually, Monfortinho and Longroiva are clearly quite different of the others, and Cró and Fonte Santa de Almeida appear together in all analysis, suggesting a strong resemblance between these waters. Thereafter, the results obtained allow us to demonstrate the role of major components of the studied thermal waters on a particular therapeutic purpose/indication and hence based on compositional and physicochemical properties partially explain their therapeutic qualities and beneficial effects on human health. This classification agreed with the results obtained for the therapeutic indications approved by the Portuguese National Health Authority and proved to be a valuable tool for the regional typology of mineral medicinal waters, constituting an important guide of the therapeutic armamentarium for well and specific-oriented pathological disturbs.  相似文献   
73.
74.
The microbiological quality of urban wastewaters presents important environmental, sanitary, and political challenges. However, the variability of untreated wastewater quality is seldom known when it comes to microbial parameters. This study aims to evaluate the variability of microbiological quality in wastewater influents from different wastewater treatment plants connected to combined and partially separate sewer networks in the Parisian area and to evaluate the impact of this variability on the treatment efficiency and on the accuracy of wastewater effluent monitoring. The densities of fecal indicator bacteria (FIB), Escherichia coli and intestinal enterococci, and their partitioning on settleable particles were analyzed at the inlet of two wastewater treatment plants during dry weather (130 composite samples and 7 days sampled every 2 hours) and storm events (39 composite samples, and 7 rain courses) from 2008 to 2012. The results showed that fecal indicator densities vary according to the network characteristics and according to the meteorological conditions. During storm events, a significant dilution of E. coli and enterococci was observed, as well as a decrease in the settleable fraction of E. coli during the maximal impact of the storm. However, storm events did not significantly impact the regular FIB monitoring. FIB removals by primary and secondary treatment were significantly correlated with FIB densities in influent wastewater; however, meteorological conditions also influenced the removal of FIB.  相似文献   
75.
The aim of the present study was to comparatively evaluate genomic damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated oral mucosa cells from crack cocaine users by micronucleus test. A total of 30 crack cocaine users and 30 health controls (non-exposed individuals) were included in this setting. Individuals had epithelial cells from cheek mechanically exfoliated, placed in fixative, and dropped in clean slides, which were checked for the above nuclear phenotypes. The results pointed out significant statistical differences (p?<?0.05) of micronucleated oral mucosa cells from crack cocaine users. Exposure to crack cocaine caused an increase of other nuclear alterations closely related to cytotoxicity such as karyolysis in oral cells as well. In summary, these data indicate that crack cocaine is able to induce chromosomal breakage and cellular death in oral mucosa cells of users.  相似文献   
76.
Soil avoidance by earthworms has been generally considered a relevant and sensitive endpoint for assessing soil contamination by xenobiotics. However, when pesticide ecotoxicological assessment is concerned, the sensitivity of the recently standardized avoidance assay has been questioned. We hypothesized that this controversy may be due to the specific pesticide mode of action of the chemicals used rather than reveal inconsistencies in the test feasibility, i.e. provided that no pesticides interfering with neuronal pathways are tested, this bioassay should keep expected high levels of sensitivity. In this study, the avoidance behaviour of the earthworm Eisenia andrei under exposure to the carbamate insecticide methomyl [S-methyl N-(methylcarbamoyloxy)thioacetimidate] was linked to the corresponding acetylcholinesterase (AChE) inhibition. Significant AChE inhibition occurred at lower concentrations (from 0.86 mg Kg?1 onwards) than significant avoidance of spiked soil (from 5.62 mg Kg?1 onwards). This indicates that assessments regarding pesticides that have neurotoxic activity may be biased if behavioral endpoints are selected. Despite theoretical hypothesis that have been raised, this should be the first study providing preliminary experimental evidence on such a link between avoidance behavior and neuronal impairment levels in earthworms. Further studies are ongoing that should refine conclusions of this study.  相似文献   
77.
The electrochemical oxidation of bifenox acid was studied at a boron-doped diamond thin film by cyclic voltammetry and galvanostatic electrolysis. The course of the electrolysis was monitored by measurement of chemical oxygen demand (COD) and by gas chromatography/mass spectrometry (GC / MS) analysis. It was found that exhaustive electrolysis leads to degradation and, ultimately, to mineralization of the starting herbicide. The degradation intermediates were identified showing that the oxidation process begins with the fragmentation of the molecule followed by reactions involving the hydroxyl radical, which is generated by the discharge of water. The study of the effect of current density and concentration showed that the degradation efficiency increases with decreasing current densities and increasing concentrations. The whole results were interpreted in a mechanistic scheme involving two oxidation pathways, the first is a direct oxidation at the electrode and the second uses hydroxyl radical as mediator of the oxidation. Finally, a kinetic study based on spectrophotometric measurements showed that the degradation process is pseudo first order.  相似文献   
78.
The joint action of pyrethroids, lambda-cyhalothrin (LC) in combination with organophosphates, fenitrothione (FNT) on antioxidant defense system and lipid peroxidation biomarkers in rat testes was studied. The results suggest that incubation of testes homogenate with different concentrations of insecticide mixture for different time intervals significantly decreased the activity of antioxidant enzymes, like glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT), and the level of reduced glutathione (GSH). In addition, a significant inhibition in transaminases (AST, ALT), phosphatases (AcP, AlP) activity and protein content were observed. On the other hand, FNT plus LC increased the cellular lipid peroxidation (LPO) level and the activity of lactate dehydrogenase (LDH). In conclusion, the use of insecticides mixture might cause marked oxidative damage in a concentration and time-dependent manner.  相似文献   
79.
The objective of this study was to determine the acute toxicity of some pesticides used in irrigated rice farming to Lithobates catesbeianus tadpoles. The LC50-96h for commercial formulations containing bentazon, penoxsulam, vegetable oil, permethrin and carbofuran, separately and their mixtures, were determined at the proportions commonly used in the field. The limits of risk concentrations of these products for the studied species were also established. The LC50-96h for tadpoles was 4,530 mg L?1 for bentazon; 7.52 mg L?1 for penoxsulam + 145.66 mg L?1 of vegetable oil; 81.57 mg L?1 for vegetable oil; 0.10 mg L?1 for permethrin; 29.90 mg L?1 for carbofuran (active ingredients), and 38.79 times the dose used in the field for the mixture of these products. The environmental risk was determined only for permethrin, and care should be taken when using the vegetable oil.  相似文献   
80.
ABSTRACT

Data from the 1990 San Joaquin Valley Air Quality Study/ Atmospheric Utility Signatures, Predictions, and Experiments (SJVAQS/AUSPEX) field program in California's San Joaquin Valley (SJV) suggest that both urban and rural areas would have difficulty meeting an 8-hr average O3 standard of 80 ppb. A conceptual model of O3 formation and accumulation in the SJV is formulated based on the chemical, meteorological, and tracer data from SJVAQS/ AUSPEX. Two major phenomena appear to lead to high O3 concentrations in the SJV: (1) transport of O3 and precursors from upwind areas (primarily the San Francisco Bay Area, but also the Sacramento Valley) into the SJV, affecting the northern part of the valley, and (2) emissions of precursors, mixing, transport (including long-range transport), and atmospheric reactions within the SJV responsible for regional and urban-scale (e.g., downwind of Fresno and Bakersfield) distributions of O3. Using this conceptual model, we then conduct a critical evaluation of the meteorological model and air quality model. Areas of model improvements and data needed to understand and properly simulate O3 formation in the SJV are highlighted.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号