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91.
依据2011年2月~2016年1月在连云港近岸海域进行的19个季节航次海洋环境综合调查结果,分析探讨了该海域主要海水要素的季节变化趋势和相关性,结合历史资料阐述和评价了海域的营养状态水平、环境质量现状及变化趋势,对存在的环境问题进行了分析.结果表明:研究海域水质状况总体良好;水质评价结果显示无机氮(DIN)是海域内最主要的环境污染因子,且DIN含量近年来有逐渐增加的趋势,年均值已经超过二类海水水质标准;此外其他环境污染因子是活性磷酸盐(DIP)、化学需氧量(COD)和油类.调查期间研究海域处于富营养化状态,潜在富营养化分析显示氮磷比值(N/P)有逐渐增加的趋势;绝大多数季节的有机污染状况为轻度污染状态.研究结论对科学、系统的认识和评估连云港近海生态环境现状及预测未来生态环境变化趋势具有重要的参考价值,对连云港近海海洋生态环境的可持续发展具有十分重要的科学意义和实际应用价值  相似文献   
92.
Traffic vehicles, many of which are powered by port fuel injection (PFI) engines, are major sources of particulate matter in the urban atmosphere. We studied particles from the emission of a commercial PFI-engine vehicle when it was running under the states of cold start, hot start, hot stabilized running, idle and acceleration, using a transmission electron microscope and an energy-dispersive X-ray detector. Results showed that the particles were mainly composed of organic, soot, and Ca-rich particles, with a small amount of S-rich and metal-containing particles, and displayed a unimodal size distribution with the peak at 600?nm. The emissions were highest under the cold start running state, followed by the hot start, hot stabilized, acceleration, and idle running states. Organic particles under the hot start and hot stabilized running states were higher than those of other running states. Soot particles were highest under the cold start running state. Under the idle running state, the relative number fraction of Ca-rich particles was high although their absolute number was low. These results indicate that PFI-engine vehicles emit substantial primary particles, which favor the formation of secondary aerosols via providing reaction sites and reaction catalysts, as well as supplying soot, organic, mineral and metal particles in the size range of the accumulation mode. In addition, the contents of Ca, P, and Zn in organic particles may serve as fingerprints for source apportionment of particles from PFI-engine vehicles.  相似文献   
93.
Simultaneous and continuous measurements of visibility, meteorological parameters and air pollutants were carried out at a suburban site in Ningbo from June 1, 2013 to May 31,2015. The characteristics of visibility and their relationships with air pollutants and meteorological factors were investigated using multiple statistical methods. Daily visibility ranged from 0.6 to 34.1 km, with a mean value of 11.8 km. During the 2-year experiment,43.4% of daily visibility was found to be less than 10.0 km and only 9.2% was greater than 20.0 km. Visibility was lower in winter with a frequency of 53.4% in the range of 0.0–5.0 km.Annual visibility had an obvious diurnal variation, with the lowest and highest visibility being 7.5 km at approximately 06:00 local time and 15.6 km at approximately 14:00 local time, respectively. Multiple correspondence analysis(MCA) indicated that the different ranges of visibility were significantly affected by different levels of pollutants and meteorological conditions. Based on the analyses, visibility was found to be an exponential function of PM_(2.5) concentrations within a certain range of relative humidity. Thus, nonlinear models combining multiple linear regressions with exponential regression were subsequently developed using the data collected from June 2014 to May 2015, and the data from June 2013 to May 2014 was used to evaluate the performance of the model. It was demonstrated that the derived models can quantitatively describe the relationships between visibility, air quality and meteorological parameters in Ningbo.  相似文献   
94.
全球海洋油气开发重特大火灾事故频发,油气生产安全面临严峻挑战,以我国浅海某中心平台组为研究对象,对可能发生的三相分离器喷射火火灾、管线交叉处喷射火火灾、生产平台池火火灾以及储罐平台池火火灾,采用FDS软件建立该平台组的火灾动力学模型,对油气泄漏后火灾的发展态势、火场温度、热辐射强度、设备温度以及不同火灾工况的对比分析,研究火灾发生后对人员伤害,以及平台上油气管线、分离器、油气储罐、平台栈桥等重要设备安全性的影响,并提出操作人员和重要设备的安全距离。针对火灾事故风险控制提出建议措施,对海上火灾风险分析未来研究方向进行阐述。  相似文献   
95.
退化土地评价及其生态重建方法研究   总被引:4,自引:0,他引:4  
本文系统分析了退化土地评价研究的历史和方法,总结了退化土地的主要类型、分布和形成机理,最后概述了退化土地重建领域的研究进展。  相似文献   
96.
The denaturing gradient gel electrophoresis (DGGE) method was applied to determine the relative genetic complexity of microbial communities in flooded paddy soil treated with herbicide quinclorac (3,7-dichloro-8-quinoline-carboylic acid). The results obtained showed a significant effect of quinclorac on the development of bacterial populations in soils contaminated with different concentrations of the herbicide at the early time after application. In general, however, the number of populations of the same soil sample treated with the same concentration of the quinclorac differed obviously with increasing incubation time within the early 8 weeks. The scale of differences in banding patterns-showed that the microbial community structures of the quinclorac-treated and non-quinclorac-treated soils were not significantly different after 21 weeks of incubation. Quantification, as demonstrated in this paper, was studied by establishing dose-response relationships. Significant pattern variations were quantified. Prominent DGGE bands were excised, cloned and sequenced to gain insight into the identities of predominant bacterial populations. The majority of DGGE band sequences were related to bacterial genera Clostridium, Sphingobacterium, Xanthomonas and Rhodococcus.  相似文献   
97.
五种重金属在小麦植株不同器官中的分布特征   总被引:21,自引:0,他引:21  
为研究Cd、Pb、As、Cu、Zn等5种重金属在小麦植株不同器官的分布特征,以郑州9023为供试品种,采用田间试验方法,应用原子吸收分光光度法和电感耦合等离子体原子发射光谱法(ICPS)分别测定了小麦植株不同器官的重金属质量分数并进行了分析。结果表明,小麦植株中较易富集Cd的器官是根、叶及废弃物,较易富集Pd、As的器官是根、茎及废弃物,较易富集Zn、Cu的器官是根、茎和籽粒;在这5种重金属中,Zn在小麦茎和籽粒中的富集系数最高,Cd在地上部分其他器官的富集系数最高,而Pb在这些器官中富集系数均为最低,Cu和As则居中。  相似文献   
98.
邯钢焦化厂1#~4#焦炉烟尘治理   总被引:1,自引:0,他引:1  
介绍了邯钢焦化厂1^#~4^#焦炉采用布袋式除尘的烟尘治理方案,装煤和出焦除尘工艺流程及部分改进措施。  相似文献   
99.
为提高稻秆的降解率及其厌氧发酵甲烷产量,采用高氨氮畜禽废水作为氮源以驯化稻田土壤微生物,优化其降解稻秆的初始pH值,并评估水解产物液体发酵产甲烷性能.结果表明,混合组驯化的微生物产纤维素酶活性及对稻秆木质素的降解率高于其它组及先前文献报道,分别达到4.01 IU和51.96%,且后期水解液中总有机碳(Total organic carbon, TOC)及还原糖含量最高.随着初始pH值的提高,稻秆中纤维素、半纤维素和木质素的降解率显著增加,稻秆水解液中的挥发性脂肪酸(Volatile fatty acids, VFAs)和TOC含量均显著增加,并在第7 d达到最高值.将水解稻秆7 d的水解液进行厌氧发酵显示,在初始pH=9.0条件下累积甲烷产量达到最大,为37.60 mL·mL-1水解液.本实验结果表明, 驯化的稻田土微生物在碱性条件下可以更有效地降解稻秆,提高水解液中TOC及VFAs含量,从而提高厌氧发酵的甲烷产量.  相似文献   
100.
纳米氧化镍(nNiO)作为一种广泛使用的纳米颗粒,其水生毒理效应研究还很有限。为探索n Ni O对海洋贝类的毒性机制,本研究将长牡蛎(Crassostrea gigas)置于不同浓度(0、1、10、100 mg·L~(-1))的n Ni O中暴露96 h,分别测定鳃和消化腺组织的丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,并通过实时荧光定量PCR技术测定了鳃和消化腺中应激蛋白HSP70和AOX基因的表达变化。结果显示:在100 mg·L~(-1)n Ni O处理下,2种组织中MDA含量均显著性升高(P0.01),显示纳米颗粒造成了长牡蛎的脂质过氧化,并可能引起相应的氧化损伤。同时,n Ni O暴露也诱导了长牡蛎抗氧化酶(SOD、CAT和POD)活性的改变。其中,SOD和CAT活性在10 mg·L~(-1)浓度处理组达到最高,而POD活性在1 mg·L~(-1)浓度组即达最高值。在高浓度n Ni O(100 mg·L~(-1))胁迫下,3种抗氧化酶的活性均比低浓度(1和10 mg·L~(-1))处理组降低,表明抗氧化酶的保护作用在较低浓度暴露下更有效;而热激蛋白(hsp70)和交替氧化酶(aox)基因却分别在长牡蛎消化腺和鳃组织中上调表达(P0.01),并表现出一定的组织差异。说明高浓度纳米颗粒暴露中主要是应激蛋白发挥了作用。本文结果为纳米氧化镍对海洋双壳贝类的毒性机制研究及生态风险评估提供了基础数据。  相似文献   
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