首页 | 官方网站   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   2714篇
  免费   60篇
  国内免费   64篇
工业技术   2838篇
  2023年   26篇
  2022年   39篇
  2021年   62篇
  2020年   52篇
  2019年   38篇
  2018年   51篇
  2017年   62篇
  2016年   74篇
  2015年   78篇
  2014年   151篇
  2013年   163篇
  2012年   157篇
  2011年   235篇
  2010年   160篇
  2009年   177篇
  2008年   145篇
  2007年   158篇
  2006年   147篇
  2005年   115篇
  2004年   91篇
  2003年   89篇
  2002年   80篇
  2001年   57篇
  2000年   49篇
  1999年   69篇
  1998年   61篇
  1997年   36篇
  1996年   37篇
  1995年   24篇
  1994年   23篇
  1993年   17篇
  1992年   19篇
  1991年   20篇
  1990年   16篇
  1989年   17篇
  1988年   7篇
  1987年   6篇
  1986年   6篇
  1985年   7篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1977年   3篇
  1975年   1篇
  1973年   1篇
  1971年   1篇
排序方式: 共有2838条查询结果,搜索用时 0 毫秒
31.
介绍了以煤气中氨为碱源,OMC-对苯二酚为催化剂的湿法脱硫工艺。生产实践表明,该工艺不但脱硫脱氰效率高,而且无废液产生,是一种清洁生产工艺。  相似文献   
32.
Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for curbing the greenhouse gas emissions and to ensure a sustainable development of power generation and other energy-intensive industrial sectors. Chemical looping systems are very promising options for intrinsically capture CO2 with lower cost and energy penalties. Gasification offers significant advantages compared with other technologies in term of lower energy and cost penalties for carbon capture, utilization of wide range of fuels, poly-generation capability, plant flexibility, lower environmental impact, etc.  相似文献   
33.
高明明  王竹  裘知  王思成  华懿 《室内设计》2023,38(2):129-135
我国乡村公共服务设施的建设在内外 合力作用下经历了由“增量”到“提质”的转变, 相关研究也从过往规划统筹的导向逐步转向以 人为本,进入百家争鸣的新时期,但其建设仍表 现出闲置和类型不全等问题。以动态发展的视 角梳理我国乡村公共服务设施配置研究的发展 历程,从配置原则、配置方法、配置结果三方面 对其进行分析,发现研究总体上对标城市社区 公共服务设施的营建逻辑,配置原则体现出效 率与公平的角力伴随以人为本的转变,配置方 法由空间因子分析转变为融合非空间因子的综 合建模,配置结果则反映出层级化配置体系逐步优化的特征。目前借鉴城市社区配置理路的研究及案例研究无法应对乡村的多样化特征和村 民需求,提出在乡村特性数据库的基础上构建“基本项+特色项”的菜单式设施功能类型框架和 在已成型的乡村内为设施科学“选址”的方向建议。  相似文献   
34.
刘倩  江裕林 《室内设计》2023,38(3):47-53
通勤效率是反映城市生活品质的重要 指标。改革开放以来,经济社会快速发展和城 镇化水平不断提高,城市职住空间关系发生深 刻变化和居民通勤行为变得日趋复杂,影响城市 空间绩效和居民生活品质;且随着多源大数据 可获得性增强,关于职住平衡及其对通勤效率 作用机制的研究愈发广泛而深入,但学者对于 职住平衡度和土地利用混合度等物质空间属性 如何影响居民通勤尚未达成一致的结论。为了 解城市日常生活中不同通勤效率居民的多元需求 和真实的通勤状态,探索提升城市居民通勤效 率的有效途径,推动城市人居环境高质量发展。 以深圳市为例,借助DAAS和ArcGIS平台利用 联通手机信令数据识别居住地和工作地,通过 LINGO软件计算过剩通勤指标,对深圳居民通 勤效率进行评价,并在区分居民工作地和居住地基础上建立多元回归模型,探究多方面因素对居民通勤效率的影响和作用机制。研究发现,区 位、职住平衡度、土地利用混合度、容积率、平均房价、公交可达性、城中村面积、工作岗位数量 和服务设施面积对居民通勤效率有重要的影响。控制其他因素对通勤效率的影响之后,无论是 居住地还是工作地,通勤效率都会随着职住平衡程度的提升而提高,而在中国已有较高密度和 混合度的背景下,通过进一步增容或功能混合以期提高通勤效率的措施则需审慎对待。研究丰富 了基于我国大中城市背景的通勤影响实证案例,为提高城市通勤效率,推动可持续交通提供有益 的政策参考。  相似文献   
35.
This work presents large-scale dye-sensitized solar cells and methods for their manufacture. A dye-sensitized solar cell device contains a photosensitive dye adsorbed on a large surface of the anode, and a transparent conductive cathode disposed opposite the anode, wherein platinum nano-catalytic particles adhere to its surface, and an electrolytic solution is sealed between the anode and the transparent conductive cathode. A titania nanotube film was fabricated by thermo-spraying titanium film on 304 stainless-steel substrate. The photo-current conversion efficiency was tested under an AM 1.5 solar simulator. The dye-sensitized solar cell device has a short current density of 8.22 mA cm–2, open voltage of 0.71 V, fill factor of 0.59, and conversion efficiency of 3.4%. The internal impedance of the dye-sensitized solar cell was detected and simulated using an electrical impedance spectra technique with inductance, resistance, and capacitance characteristics. The stainless-steel/titania, titania/electrolyte, electrolyte, and electrolyte/(platinum/indium tin oxide) interfaces were simulated using an resistor–capacitor parallel circuit, and bulk materials such as stainless steel, tin doped indium oxide, and conducting wire were simulated by using a series of resistors and inductance.  相似文献   
36.
在集团公司不断提高客户服务满意度的要求下,提高投诉处理的及时率,提高投诉处理的效率,减少每万用户投诉比成为越来越紧迫的任务。在完成这个任务的过程中,有一个关键的步骤就是如何提高公告信息发布的效率。这个网络类公告信息包括工程信息和故障信息。发布是指在EOMS上发布并在BOSS系统上呈现给客服人员查询使用。这个效率包括公告信息的及时率、准确率和有效率。  相似文献   
37.
ICT infrastructure investments in educational institutions have been one of the key priorities of education policy during the last decade. Despite the attention, research on the effectiveness and efficiency of ICT is inconclusive. This is mainly due to small-scale research with weak identification strategies which lack a proper control group. Using the 2011 ‘Trends in International Mathematics and Science Study’ (TIMSS) data, we define by a Mahalanobis matching a control group with similar student, teacher, school and regional characteristics. The results indicate that accounting or not accounting for these characteristics, may considerably alter the estimated impact of ICT. This suggests that a correction for characteristics related to the student population, teaching staff, administrative personnel and school management is warranted in the evaluation of the impact of ICT.  相似文献   
38.
A system based a fluidized bed gasifier with steam as a gasifying agent is investigated in details. Comparing the synthesis of gas compositions with experimental data available in the literature is used to validate the model. The synthesis of gas composition and efficiencies of the system is investigated respect to different biomasses considered as gasification fuels. The results indicate that the molar fractions of hydrogen and carbon dioxide are increased and the molar fraction of carbon monoxide is reduced with steam to biomass ratio (STBR). The hydrogen and cold gas efficiencies are improved with decreasing STBR. Hydrogen, cold gas, and exergy efficiencies are enhanced with temperature. The results illuminate that pine sawdust and straw have the highest hydrogen production and legume straw produces the lowest CO molar fraction. Straw has the highest hydrogen efficiency, eucalyptus and straw have the highest cold gas efficiency, and eucalyptus has the highest exergy efficiency. A systematical analytical hierarchy process (AHP)/technique for order preferences by similarity to ideal solution (TOPSIS) couple method are utilized to select the best alternative. The results illuminate that eucalyptus, straw, and pine sawdust are the best candidates, respectively as gasification fuel based on the considered criteria.  相似文献   
39.
Five fully formulated wind turbine gear oils were characterised. The gear oils have 320 ISO VG grade and different formulations: ester, mineral, PAO, PAG and mineral+PAMA.A back-to-back FZG test machine, with re-circulating power, was used and a torque-cell was included on the test rig in order to measure the torque loss. Eight thermocouples were included to monitor the temperatures in different locations of the test rig.Tests at 1.13, 2.26 and 6.79 m/s were performed for different FZG load stages: K1, K5, K7 and K9. Both gearboxes were jet-lubricated with an oil flow of 3 l/min. The input flow temperature was kept almost constant (80 ±1 °C).Friction generated between the meshing teeth, shaft seals and rolling bearing losses was predicted.  相似文献   
40.
In establishing an economical testing program the costs of routine analytical tests must be weighed against losses due to shipping material which is either above or below stated specifications. A method for obtaining an optimum sampling and testing procedure is described and examples given.  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-23

京公网安备 11010802026262号