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   942篇
  免费   50篇
  国内免费   6篇
电工技术   7篇
综合类   1篇
化学工业   171篇
金属工艺   34篇
机械仪表   43篇
建筑科学   45篇
能源动力   62篇
轻工业   101篇
水利工程   6篇
石油天然气   7篇
无线电   120篇
一般工业技术   150篇
冶金工业   82篇
原子能技术   9篇
自动化技术   160篇
  2024年   8篇
  2023年   9篇
  2022年   30篇
  2021年   53篇
  2020年   45篇
  2019年   47篇
  2018年   52篇
  2017年   39篇
  2016年   47篇
  2015年   15篇
  2014年   44篇
  2013年   98篇
  2012年   40篇
  2011年   67篇
  2010年   55篇
  2009年   58篇
  2008年   65篇
  2007年   47篇
  2006年   26篇
  2005年   22篇
  2004年   13篇
  2003年   10篇
  2002年   16篇
  2001年   13篇
  2000年   7篇
  1999年   1篇
  1998年   26篇
  1997年   7篇
  1996年   16篇
  1995年   5篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1990年   1篇
  1985年   2篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
排序方式: 共有998条查询结果,搜索用时 15 毫秒
61.
牛奶蛋白纤维(第Ⅰ部分)   总被引:1,自引:0,他引:1  
牛奶蛋白纤维是一种新颖的工业生产纤维,中国已拥有2项发明专利.2004年它就已经通过了国际生态纺织品Oeko-Tex标准100认证.牛奶蛋白纤维是利用新型生物工程技术将牛奶去水脱脂,加工成适用于湿法纺丝工艺的蛋白浆后制得的纤维.它对皮肤友好,手感舒适,色彩鲜艳,具有很好的可染性.牛奶蛋白纤维可以纯纺或与羊绒、蚕丝、棉、毛、麻及其他纤维混纺.  相似文献   
62.
The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph2I+PF6?). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air.  相似文献   
63.
The purpose of this paper is to estimate the anthropometric characteristics of the Turkish population by geographical region, age and gender. A survey of 4205 samples consisting of 2263 male and 1942 female civilian subjects was done in the year of 2007. It contains data from all seven geographical regions of Turkey and from all age groups. In the study, height and weight of the subjects were measured by age. Then, these data were used for estimating anthropometric measurements of the Turkish population. The main result of this study is the anthropometric measurements table for Turkey which shows 37 measurements that are commonly used in industry. The anthropometric measurements that are used to make the designs fit human shape and the human/machine or human/environment interface should be updated through time due to changing body types over time (secular trends) due to numerous factors. In this study, we not only update these variables, which are 30 years old, but also investigate the age and region effects on stature and weight of Turkish population.Relevance to industry: During the design phase of a product, incorporating anthropometric information would yield more efficient designs, which are more user friendly, safer and enable higher performance and productivity. So the anthropometric measurements table that is extracted from this study can be used by industry to produce better human oriented products for Turkish population.  相似文献   
64.
An air pollution modeling study was conducted to investigate the odorous effects of volatile organic compounds (VOCs) emissions from a sanitary landfill area on ambient air quality. The atmospheric dispersion of hydrogen sulfide (H2S) and 22 VOCs was modeled. Industrial Source Complex v3 Short Term (ISCST3) model was used to estimate hourly concentrations of odorous VOCs over the nearest residential area. Odor thresholds of VOCs of interest were also found in the literature. Results showed that short-term averages of three odorous VOCs, namely ethyl mercaptan, methyl mercaptan and hydrogen sulfide, exceeded their odor thresholds, which are reported to be 0.022, 0.138 and 11.1 μg/m3, respectively, at several points within the domain. Their highest concentrations within Gokturk County were estimated to be 0.09387 μg/m3 for ethyl mercaptan, 0.07934 μg/m3 for methyl mercaptan and 6.315 μg/m3 for hydrogen sulfide. Short-term model results revealed the occasional odor problems being reported for Gokturk County. Hourly concentrations were used to obtain frequencies of odor episodes in Gokturk County via a probability analysis. The results showed that ethyl mercaptan concentrations did not exceed its odor threshold during more than 8.84% of the time. Similarly, the maximum odor episode frequencies for methyl mercaptan and hydrogen sulfide were 0.98% and 0.34% of the time, respectively.  相似文献   
65.
The purpose of this research is an experimental study of Calophyllum inophyllum (CI)-based trymethylolpropane (TMP) ester as an energy-saving and biodegradable lubricant and compare it with commercial lubricant and paraffin mineral oil using a four-ball tribometer. CI-based TMP ester is a renewable lubricant that is nonedible, biodegradable, and nontoxic and has net zero greenhouse gases. The TMP ester was produced from CI oil, which has high lubricity properties such as higher density, higher viscosity at both 40°C and 100°C and higher viscosity index (VI). Experiments were conducted during 3,600 s with constant load of 40 kg and constant sliding speed of 1,200 rpm at temperatures of 50, 60, 70, 80, 90, and 100°C for all three types of lubricant. The results show that CI TMP ester had the lowest coefficient of friction (COF) as well as lower consumption of energy at all test temperatures, but the worn surface roughness average (Ra) and wear scar diameter were higher compared to paraffin mineral oil and commercial lubricant. Before 80°C, CI TMP ester actually has a higher flash temperature parameter (FTP) than paraffin mineral oil and as the temperature increases, the FTP of TMP ester decreases. The worn surfaces of the stationary balls were analyzed by scanning electron microscopy (SEM) and results show that CI TMP ester has the highest wear compared to paraffin mineral oil and lowest wear compared to commercial lubricant. However, CI TMP ester is environmentally desired, competitive to commercial lubricant, and its use should be encouraged.  相似文献   
66.
ZnO nanoparticle–based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values) were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL) process on cotton fabrics properties.  相似文献   
67.
Proximate composition and fatty acid (FA) profile of three commercial sea cucumbers; Holothuria tubulosa, Holothuria polii and Holothuria mammata caught from Aegean Sea of Turkey were analysed. The effects of regional variation and drying process on FA composition were also investigated. Moisture, protein, fat and ash contents of the species ranged between 81.24% and 85.24%, 7.88% and 8.82%, 0.09% and 0.18%, and 5.13% and 7.85%, respectively, with a significant changes among species (P < 0.05) with some exceptions. Although FA values varied significantly (P < 0.05) among species and regions, the changes for most FA types representing the same region for different species were not significantly different. Total polyunsaturated fatty acids (PUFA) were found to be higher than total saturated (SFA) and monosaturated FAs (MUFA) accounting for 53.0–62.12% for ∑PUFA, 13.28–16.41% for ∑MUFA and 13.99–19.21% for ∑SFA. While some individual SFAs and PUFAs decreased after drying process, various individual FAs of MUFA increased in their amounts (P < 0.05). Among PUFAs, the highest mean value of eicosapentaenoic acid and docosahexaenoic acid for all regions were determined for H. polii as 7.25% and H. tubulosa as 12.37% in fresh samples, respectively. This study represents new information relating to FA contents and drying effect on FA profile for these species.  相似文献   
68.
Oguz Arslan   《Energy》2011,36(5):2528-2534
Recent technical developments have made it possible to generate electricity from geothermal resources of low and medium enthalpy. One of these technologies is the Kalina Cycle System. In this study, electricity generation from Simav geothermal field was investigated using the Kalina cycle system-34 (KCS-34). However, the design of these technologies requires more proficiency and longer times within complex calculations. An artificial neural network (ANN) is a new tool used to make a decision for the optimum working conditions of the processes within the expertise. In this study, the back-propagation learning algorithm with three different variants, namely Levenberg-Marguardt (LM), Pola-Ribiere Conjugate Gradient (CGP), and Scaled Conjugate Gradient (SCG), were used in the network so that the best approach could be found. The most suitable algorithm found was LM with 7 neurons in a single hidden layer. The obtained weights were used in optimization process by coupling the life-cycle-cost concepts.  相似文献   
69.
<正>一座建筑的性能应当如何来衡量?除了通过统治当代建筑舆论的美学、技术以及经济价值来进行描述之外,我们还能够如何来阐释一座建筑,尤其是一座致力于庇护那些渴望展现自己的艺术家的建筑?有人会问成功的表演是如何实现的,表演者是如何进行伪装的、又是如何展现自己的?根据海德格尔的理论,当我们看不到钉子的时候,铁锤的表现才是成功的;钉子本身的出现通常表明出现了问题。  相似文献   
70.
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