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   6592篇
  免费   562篇
  国内免费   216篇
电工技术   54篇
综合类   831篇
化学工业   2501篇
金属工艺   41篇
机械仪表   35篇
建筑科学   1657篇
矿业工程   143篇
能源动力   402篇
轻工业   673篇
水利工程   177篇
石油天然气   279篇
武器工业   1篇
无线电   7篇
一般工业技术   168篇
冶金工业   317篇
原子能技术   27篇
自动化技术   57篇
  2024年   14篇
  2023年   61篇
  2022年   120篇
  2021年   135篇
  2020年   163篇
  2019年   141篇
  2018年   134篇
  2017年   182篇
  2016年   224篇
  2015年   188篇
  2014年   354篇
  2013年   389篇
  2012年   548篇
  2011年   528篇
  2010年   423篇
  2009年   459篇
  2008年   374篇
  2007年   498篇
  2006年   475篇
  2005年   378篇
  2004年   306篇
  2003年   293篇
  2002年   185篇
  2001年   130篇
  2000年   111篇
  1999年   92篇
  1998年   58篇
  1997年   39篇
  1996年   40篇
  1995年   45篇
  1994年   22篇
  1993年   36篇
  1992年   34篇
  1991年   29篇
  1990年   11篇
  1989年   16篇
  1988年   23篇
  1987年   19篇
  1986年   17篇
  1985年   34篇
  1984年   22篇
  1983年   12篇
  1982年   2篇
  1980年   1篇
  1951年   5篇
排序方式: 共有7370条查询结果,搜索用时 15 毫秒
161.
刘正誉 《上海造纸》2012,(1):65-67,70
介绍南纸公司300t/d废纸脱墨浆(DIP)生产线改造成能配抄中、低档文化印刷纸所增加的设备及功能,改造后设备的运行状况及生产工艺的调整。  相似文献   
162.
许洲 《净水技术》2014,(2):13-16
根据上海市竹园第一污水处理厂的运行数据,研究了该厂的污泥产率。结果表明竹园第一污水处理厂每万吨水产泥率的变化范围为0.38—1.44tSS/万M2;剩余污泥的表观产率系数(Lobs)和合成产率系数(y)分别为0.56和0.58kgVSS/kgBOD,均在正常范围以内;衰减系数(虬)为0.006d-1;惰性ss产泥率的变化范围为0.20~0.50tSS/万M2。  相似文献   
163.
污泥和石英砂尾矿制备建材陶粒的烧结时间研究   总被引:1,自引:0,他引:1       下载免费PDF全文
以城市污水处理厂的污泥与石英尾砂为主要原料,添加适当助剂如河道底泥、矿山浮选脱硫废渣,可制备建材陶粒.在原料配比m(石英尾砂)∶m(污泥)∶m(粘合剂)∶m(河道底泥)=4∶4∶3∶3、进料温度400℃、预热时间20min、焙烧温度1100℃、焙烧时间25 min的条件下,制备的陶粒强度为5.11 MPa,吸水率为11.7%,堆积密度为913kg/m3.  相似文献   
164.
通过现场试验,考查了多环芳烃(PAHs)从污泥向芦苇的转移以及PAHs在芦苇各部位的分布情况。受试芦苇植于污泥干化芦苇床内,芦苇床规格3 m×1 m×1.3 m,其中高度含0.65 m填料层和0.65 m超高。试验进行了3 a,包括2 a的污泥负荷期和1 a的闲置期。2 a负荷期内共进泥8.4 m(含水率99.14%),污泥PAHs含量平均5.69 mg·kg -1。原生芦苇茎和叶中的PAHs含量相对较高,达到2.198和2.583 mg·kg -1 (DW),分别是芦苇根PAHs含量的2.44和2.87倍,且以低环PAHs为主。运行结果表明,受试芦苇对污泥中的PAHs产生了明显的富集作用。运行第2年9、10和11月取污泥干化芦苇床芦苇样品并进行检测,发现芦苇根茎叶内PAHs含量呈逐月升高趋势;第3年11月芦苇根茎叶所含PAHs总量分别为7.642、7.713、7.946 mg·kg -1 (DW),相对原生芦苇分别提高了8.50、3.52和3.08倍,且以低环PAHs为主,根茎叶低环PAHs含量占PAHs总量的55.14%、56.96%和44.59%。芦苇中PAHs的含量与植物含脂率具有显著的正相关关系,而与芦苇的含水量无关。  相似文献   
165.
研究了微波加热温度和温升速率对污泥脱水特性的影响,并对微波处理后污泥的CST、粘度、沉降比、含水率、上清液COD含量、Zeta电位、形态学特征进行了测试与分析.实验结果表明,温升速率为10℃/min,加热到70~80℃时中水站污泥脱水特性较好.随温度上升,污水处理厂污泥的SV、粘度、含水率相应降低,COD含量逐渐增加;对比直接从污泥图像与据污泥颗粒的粒径分布得到分形维数与粒径,发现在不同的加热条件下污泥形态有明显变化,加热到60~80℃时脱水特性较好,70℃时含水率最低为83.12%.  相似文献   
166.
Sonication is a well‐known sludge pretreatment technique with the advantages of simple operation and high efficiency. However, it is an energy‐intensive process. Hence, it is very important to predetermine its sludge disintegration efficiency at varying pretreatment conditions in order to minimize the ultrasonic energy consumption. In this study, it was found that the ultrasonic sludge disintegration occurred in two stages: rapid and subsequent slow disintegration stages. For this reason, it was aimed to develop a simple and accurate mathematical model to describe the two‐stage sludge disintegration as a function of pretreatment conditions. Sludge concentration and ultrasonic density along with sonication period were involved in this model as independent variables. It was determined that the mathematical model can predict accurately the degree of sludge disintegration. Thus, the proposed model was seen to be very useful for evaluating the disintegration efficiency and/or for process design using the operating parameters under different conditions.  相似文献   
167.
结合当前污泥处置技术及发展趋势,在分析桂林市各污水处理厂污泥特性的基础上,提出了桂林市污泥处置以高温好氧堆肥技术为路线,污泥首选土地利用,在不具备土地利用的条件下进行卫生填埋的发展方向。  相似文献   
168.
This study analysed the enhanced biological phosphorus removal (EBPR) microbial community and metabolic performance of five full-scale EBPR systems by using fluorescence in situ hybridisation combined with off-line batch tests fed with acetate under anaerobic–aerobic conditions. The phosphorus accumulating organisms (PAOs) in all systems were stable and showed little variability between each plant, while glycogen accumulating organisms (GAOs) were present in two of the plants. The metabolic activity of each sludge showed the frequent involvement of the anaerobic tricarboxylic acid cycle (TCA) in PAO metabolism for the anaerobic generation of reducing equivalents, in addition to the more frequently reported glycolysis pathway. Metabolic variability in the use of the two pathways was also observed, between different systems and in the same system over time. The metabolic dynamics was linked to the availability of glycogen, where a higher utilisation of the glycolysis pathway was observed in the two systems employing side-stream hydrolysis, and the TCA cycle was more active in the A2O systems. Full-scale plants that showed higher glycolysis activity also exhibited superior P removal performance, suggesting that promotion of the glycolysis pathway over the TCA cycle could be beneficial towards the optimisation of EBPR systems.  相似文献   
169.
Hong Kong practices seawater toilet flushing covering 80% of the population. A sulfur cycle-based biological nitrogen removal process, the Sulfate reduction, Autotrophic denitrification and Nitrification Integrated (SANI®) process, had been developed to close the loop between the hybrid water supply and saline sewage treatment. To enhance this novel process, granulation of a Sulfate-Reducing Up-flow Sludge Bed (SRUSB) reactor has recently been conducted for organic removal and provision of electron donors (sulfide) for subsequent autotrophic denitrification, with a view to minimizing footprint and maximizing operation resilience. This further study was focused on the biological and physicochemical characteristics of the granular sulfate-reducing sludge. A lab-scale SRUSB reactor seeded with anaerobic digester sludge was operated with synthetic saline sewage for 368 days. At 1 h nominal hydraulic retention time (HRT) and 6.4 kg COD/m3-d organic loading rate, the SRUSB reactor achieved 90% COD and 75% sulfate removal efficiencies. Granular sludge was observed within 30 days, and became stable after 4 months of operation with diameters of 400–500 μm, SVI5 of 30 ml/g, and extracellular polymeric substances of 23 mg carbohydrate/g VSS. Fluorescence in situ hybridization (FISH) analysis revealed that the granules were enriched with abundant sulfate-reducing bacteria (SRB) as compared with the seeding sludge. Pyrosequencing analysis of the 16S rRNA gene in the sulfate-reducing granules on day 90 indicated that the microbial community consisted of a diverse SRB genera, namely Desulfobulbus (18.1%), Desulfobacter (13.6%), Desulfomicrobium (5.6%), Desulfosarcina (0.73%) and Desulfovibrio (0.6%), accounting for 38.6% of total operational taxonomic units at genera level, with no methanogens detected. The microbial population and physicochemical properties of the granules well explained the excellent performance of the granular SRUSB reactor.  相似文献   
170.
The strength of granular sludge is essential for the mechanical stability of the granules. Inorganic precipitants form a major factor influencing the strength of the granules. To check the possibility of apatite accumulation in anammox granules, and study its contribution to the mechanical strength of granules, anammox granular sludge was collected from Dokhaven municipal wastewater treatment plant, the Netherlands. Mineral precipitation inside the granules was visualized by micro-computed tomography, and apatite was identified by electron probe microanalysis and X-ray powder diffraction. The mechanical strength of anammox granules was measured by a low load compression tester. The contribution of apatite to the mechanical strength was evaluated by the generalized Maxwell model. Ca–PO4 minerals are reported to accumulate in anammox granules. A transformation of Ca–PO4 happens, and apatite is the final stable form. The accumulation of apatite increases the mechanical strength of anammox granules. A fast method to monitor and evaluate the accumulation of minerals in anammox granules was proposed.  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