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排序方式: 共有911条查询结果,搜索用时 702 毫秒
71.
对现有粪便处理厂粪便消化液处理工艺进行了分析,找出了存在的问题,并根据工程改造的原则,将沉淀池改为缺氧池和厌氧池,SBR池改为lCEAS池,采用改良A2+ICEAS组合工艺处理粪便消化液.结合工程改造情况,介绍了主要构筑物和设计参数,并对经济技术指标进行了分析,为相关工程设计提供借鉴.  相似文献   
72.
济阳坳陷奥陶系烃源岩生物标志物地球化学特征   总被引:1,自引:1,他引:0  
利用生物标志物分析技术,结合其他地球化学资料探讨了济阳坳陷不同地区奥陶系烃源岩有机质的生物来源、成熟度和沉积环境。结果表明,早古生代藻类浮游植物的大量繁盛和细菌微生物强烈活动的产物是济阳坳陷奥陶系烃源岩有机.质生物来源构成的物质基础。烃源岩有机质丰度较低,有机质类型以Ⅰ型干酪根为主。烃源岩抽提物中Pr/Ph值均小于1,表明沉积环境较还原。等效镜质组反射率及芳烃成熟度参数显示济阳坳陷奥陶系烃源岩大多达到高成熟阶段。部分达到成熟、过成熟阶段。  相似文献   
73.
We examined a suite of environmental contaminants and exposure endpoints in blackcrowned night-heron (Nycticorax nycticorax, BCNH) embryos collected in 2002 from colonies in Illinois, Minnesota, and Virginia. Embryos from the Lake Calumet, IL, colony had greater exposure to polychlorinated biphenyls (PCBs), 4,4’-dichlorodiphenyldichloroethylene (DDE), dieldrin, transnonachlor, oxychlordane, cobalt, copper, and selenium than did those from northwest MN and coastal VA. Embryos from IL and VA contained greater concentrations of mercury and zinc than those from MN, whereas the latter had greater accumulation of lead. Greater exposure of IL embryos to PCBs was reflected in greater ethoxyresorufin-O-deethylase and benzyloxyresorufin-O-dealkylase induction. However, measures of oxidative stress and genotoxicity were similar to those in embryos from the other colonies examined, and no overt toxic effects of contaminant exposure such as embryo mortality or malformations were observed. Although efforts to clean up the south Chicago environment are ongoing, Lake Calumet BCNH, and undoubtedly other piscivorous wildlife foraging in the region, continue to be exposed to a variety of environmental contaminants. Life-history characteristics of this species make it ideal as an environmental sentinel for the success of the cleanup of the south Chicago environment.  相似文献   
74.
利用气相色谱-质谱(GC/MS)联用技术,对现代活体不同生长期油松松针中提取的生物标志化合物特征进行系统分析和研究,检测出丰富的类脂物分子,包括正构烷烃、饱和脂肪酸甲酯、脂肪酸乙酯和正烷基-2-酮等。随着生长期的增长,松针正构烷烃的碳数分布范围和主峰碳数不变,均呈现奇碳优势;正构烷烃∑C21-/∑C22+平均值为0.013,比值较低,显示高碳数正构烷烃优势,反映了样品采集区域(干旱荒漠地区)高等陆源有机质的特征;正构烷烃∑C21-/∑C22+比值和CPI、OEP随着生长期的增长均呈现规律性降低,记录了植物叶子生长过程中环境条件变化的相关信息;从生长初期(2个月)至枯萎过程中,脂肪酸甲酯、乙酯以及正烷基-2-酮类化合物均被检出,这3类化合物的形成主要是松针叶片在生长过程中的自身产物。样品中脂肪酸甲酯和正烷基-2-酮的∑C21-/∑C22+比值均随生长时间的增长呈现规律性增加,表明松针叶片低碳数脂肪酸甲酯(C13~C21)和小于C20的正烷基-2-酮随着生长期的增长明显增加。研究样品的脂肪酸乙酯的∑C21-/∑C22+比值较低,平均为0.007,显示高碳数脂肪酸乙酯占有明显优势。不同生长期松针中CPI值特征表明,脂肪酸甲酯具有显著奇碳优势、乙酯具有偶碳优势、正烷基-2-酮显示高碳数奇碳优势,此分布特征与现代土壤中该类型化合物的分布特征相近,表明它们可能是现代土壤中相应各类有机质的重要来源。  相似文献   
75.
Secondary sewage effluents are discharged in significant quantities in aquatic environments delivering pollutants that were not removed during treatment; yet advanced treated effluents are not lacking of contaminants. In this study, biochemical biomarkers were measured in liver and kidney of rainbow trout (Oncorynchus mykiss) exposed to unchlorinated, chlorinated and tertiary treated secondary sewage effluents. In addition, organic matter, nitrogen and suspended solids were assayed, while a common bioassay, Daphnia magna 21d reproduction test was also applied in order to examine potential relation between the performed bioassay and the biomarkers. Processes using oxidative conditions, such as ozonation and chlorination, resulted in significantly increased breeding rate (up to 74%) of the organism. Biomarkers measurements incorporated the determination of total glutathione (GSH), glutathione S-transferases (GST), glutathione peroxidase (GPX), lipid peroxidation (LPO) and an innovative biomarker in such applications, haem peroxidase. In general, the response of biomarkers was dependent upon the treatment method and it was tissue specific. Secondary effluents inhibited liver GST and haem peroxidase, while GSH levels and LPO were significantly provoked in liver. Ozonation provoked hepatic peroxidation, in terms of haem peroxidase and LPO, and GST; while the protective (to Reactive Oxidant Species – ROS) GSH was depleted, suggesting extended ROS attack to the organism. Similar response of biomarkers (but to a lesser extend) was observed after exposure of trout to effluents submitted to both coagulation and ozonation, emphasizing the significance of removing the residual organic matter by other methods than oxidative ones. Ozonation also enhanced renal LPO and GPX; however the former employment of coagulation limited the peroxidation phenomena. Chlorination mainly affected the levels of total GSH in both tissues.  相似文献   
76.
二氧化氯对污水厂出水的消毒及综合影响研究   总被引:1,自引:0,他引:1  
介绍了以二氧化氯作为大型城市污水处理厂出水消毒剂的生产性应用情况,系统地研究了二氧化氯在取得良好消毒效果的同时,对出水中BOD5、COD、NH_3-N、SS、TP的影响.评估了二氧化氯作为污水处理厂出水消毒剂的优势,以及对出水水质的改善效果,从而为其在大型城市污水厂的推广奠定了基础.  相似文献   
77.
马鞍山市第二污水处理厂消毒方式比选及应用   总被引:1,自引:0,他引:1  
王雷 《山西建筑》2009,35(33):188-189
针对常见的几种消毒方法,从消毒的基本原理、运行的安全可靠性、投资及运行费用等方面进行比较,通过马鞍山市第二污水处理厂的应用实例,阐明了直接投加次氯酸钠溶液对污水厂出水进行消毒具有初始投资小、运营成本低、操作方便、安全可靠、易于维护等优点,值得大范围推广。  相似文献   
78.
Oil samples from six oilfields in the Central Niger Delta were analyzed for normal alkanes, aliphatic isoprenoid hydrocarbons, aromatic hydrocarbons and biomarkers using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The study was carried out with the aim of assessing the origin and thermal maturity of the oils and the depositional environment of the organic matter from which they were derived, and to evaluate similarities (or differences) among the oils from the Central Niger Delta in comparison to those from other parts of the Delta. The ratios of n-alkanes and aliphatic isoprenoids showed that Pr/nC17 ranged from 0.56 to 0.86 while Ph/nC18 ranged from 0.22 to 0.31 indicating that the oils were derived from organic matter of both terrestrial and marine origin. Pristane/phytane ratios ranged from 2.67 to 3.50, suggesting that the organic matter was deposited in generally oxidizing environments. The oleanane index, which ranged from 0.07 to 1.39, and other biomarker data also indicate contributions from both marine and terrestrial organic matter. Both saturated and aromatic hydrocarbon biomarker data indicate that the oils are thermally mature. The study showed that the Central Niger Delta oils have organic geochemical characteristics similar to those of oils from other parts of the Delta. However, there is a striking difference in the distribution of aromatic hydrocarbons, and this may in future be used as a tool with which oils from different parts of the Delta can be differentiated.  相似文献   
79.
Clinical research aiming at objectively identifying and characterizing diseases via clinical observations and biological and radiological findings is a critical initial research step when establishing objective diagnostic criteria and treatments. Failure to first define such diagnostic criteria may lead research on pathogenesis and etiology to serious confounding biases and erroneous medical interpretations. This is particularly the case for electrohypersensitivity (EHS) and more particularly for the so-called “provocation tests”, which do not investigate the causal origin of EHS but rather the EHS-associated particular environmental intolerance state with hypersensitivity to man-made electromagnetic fields (EMF). However, because those tests depend on multiple EMF-associated physical and biological parameters and have been conducted in patients without having first defined EHS objectively and/or endpoints adequately, they cannot presently be considered to be valid pathogenesis research methodologies. Consequently, the negative results obtained by these tests do not preclude a role of EMF exposure as a symptomatic trigger in EHS patients. Moreover, there is no proof that EHS symptoms or EHS itself are caused by psychosomatic or nocebo effects. This international consensus report pleads for the acknowledgement of EHS as a distinct neuropathological disorder and for its inclusion in the WHO International Classification of Diseases.  相似文献   
80.
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