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   22887篇
  免费   1850篇
  国内免费   970篇
电工技术   1429篇
技术理论   4篇
综合类   1195篇
化学工业   3972篇
金属工艺   1126篇
机械仪表   1452篇
建筑科学   1530篇
矿业工程   658篇
能源动力   652篇
轻工业   1285篇
水利工程   391篇
石油天然气   1324篇
武器工业   169篇
无线电   3014篇
一般工业技术   3006篇
冶金工业   1124篇
原子能技术   191篇
自动化技术   3185篇
  2024年   39篇
  2023年   374篇
  2022年   570篇
  2021年   960篇
  2020年   724篇
  2019年   607篇
  2018年   726篇
  2017年   724篇
  2016年   694篇
  2015年   898篇
  2014年   1114篇
  2013年   1440篇
  2012年   1426篇
  2011年   1544篇
  2010年   1207篇
  2009年   1236篇
  2008年   1187篇
  2007年   1145篇
  2006年   1171篇
  2005年   1058篇
  2004年   700篇
  2003年   660篇
  2002年   574篇
  2001年   475篇
  2000年   553篇
  1999年   618篇
  1998年   542篇
  1997年   488篇
  1996年   455篇
  1995年   334篇
  1994年   310篇
  1993年   219篇
  1992年   176篇
  1991年   141篇
  1990年   130篇
  1989年   98篇
  1988年   81篇
  1987年   50篇
  1986年   45篇
  1985年   35篇
  1984年   20篇
  1983年   16篇
  1982年   32篇
  1981年   22篇
  1980年   16篇
  1979年   10篇
  1978年   11篇
  1977年   11篇
  1976年   12篇
  1971年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Huang  Yongwen  Li  Jiao  Sun  Tan  Xian  Guojian 《Scientometrics》2020,122(1):381-396
Scientometrics - Institution information specification and correlation is a necessity for research evaluation and resource sharing, current attempts are mainly focused on institution name...  相似文献   
62.
The flammability behaviors of ammonium polyphosphate/aluminum hydroxide/mica/silicone rubber (APP/Al[OH]3/mica/SiR) ceramifying composites containing APP, Al[OH]3, and mica are investigated by cone calorimeter test. The thermal degradation and the synergistic effect of APP/Al(OH)3/mica/SiR composites are investigated by thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. APP/Al(OH)3/mica/SiR composites with 25 wt% of APP, 20 wt% of Al(OH)3, 25 wt% of mica, and 30 wt% SiR presents a much lower total heat release, the value of peak heat release rate (PHRR), the maximum average heat release rate, the longest time to ignition, and time to the PHRR (tPHRR), compared with the flame-retardant properties from composites with filler of APP and mica or APP and Al(OH)3 alone. The results indicate that there is an excellent synergism in APP, Al(OH)3, and mica, which endows APP/Al(OH)3/mica/SiR composites with both good flame retardancy and fire prevention. The study on the synergism effect between fire prevention and flame retardancy of APP/Al(OH)3/mica/SiR composites indicates that compounds containing P-O-Al are formed due to the reaction between APP and Al(OH)3 during combustion in the early stage and a coherent, dense, and sealed structure is formed due to the reaction in mica, phosphates, and the thermal decomposition products of SiR during combustion in the later stage.  相似文献   
63.
应对告警风暴告警的系统优化策略   总被引:1,自引:0,他引:1  
长期以来,随着网络规模的扩大,告警风暴一直是电信网络管理工作的重点与难点.通过对现有告警堆积日常处理经验的研究,包括融合对硬件架构调整、软件调整、中间件配置优化等方法,得到一套解决告警风暴的处理思路,为电信运营商解决此类问题提供借鉴经验.  相似文献   
64.
65.
在地震测井施工中,为监测地下检波器的运动特征,需应用三维监测技术。首先从映射几何的角度深入分析OpenGL的三维监测技术,建立OpenGL虚拟场景,然后分析检波器模型内外方位元素的表达,利用三维绘图技术建立检波器的立体模型,最后对所获取的坐标数据进行快速的三维绘图技术处理,形成实时可靠的立体模拟界面。实验结果表明:检波器的方位角模拟精确度能保证在1°以内,满足后期简化数据处理的要求。该技术应用在地震测井中时,具有远程、可靠、无损检测等特点,为操作人员提供直观可靠的观测决策平台,并且结合实际需求能够扩展多种功能模块,可广泛应用于测井过程中方位数据的获取。  相似文献   
66.
67.
This article focuses on controlling the morphology of regenerated cellulose aerogel (RCA) and its application as a template for the preparation of functional cellulose nanoparticles (FCNPs). RCA is prepared by lyophilizing cellulose hydrogel which is fabricated through a sol–gel method in sodium hydroxide (NaOH)/urea aqueous solution. The morphology of RCA is adjusted by varying the gelation temperature and time. With the gelation temperature and time increasing, lamellar RCA transforms into strings of cellulose nanoparticles. Subsequently, RCA with the morphology of "strings of nanoparticles" is modified through the bulk condensation of l -lactic acid and RCA. Eventually, the prepared functionalized RCA (FRCA) is dispersed in an organic solvent to obtain purified FCNPs. The results demonstrate that single FCNP can be obtained by dispersing FRCA in dimethyl sulfoxide. Moreover, the prepared FCNPs have uniform size, good thermal-stability, and increasing hydrophobicity, which are ideal candidates for polymer composites in terms of fillers.  相似文献   
68.
Increasing evidences suggest that inflammation plays an important role in the pathogenesis of coronary artery disease (CAD). Numerous inflammatory cytokines and related genes mediate adverse cardiovascular events in patients with CAD, such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and Homer in the present study. The study was carried out on 163 CAD patients at different stages and 68 controls. The gene expression of Homer1, Homer2, Homer3, IL-1β, and TNF-α in the peripheral blood leukocytes were measured by real-time polymerase chain reaction. The mRNA levels of Homer1, IL-1β, and TNF-α in CAD patients were significantly higher than those in the control group, but not Homer2 and Homer3. However, there was no considerable difference in the mRNA levels of Homer1, IL-1β, and TNF-α among AMI, UAP, and SAP three subgroups of CAD. The receiver operating characteristic (ROC) curves showed that Homer1 had a better diagnostic value for UAP patients compared with IL-1β and TNF-α. Like IL-1β and TNF-α, Homer1 may also be an important participant of atherosclerotic plaque development and eventually rupture. The results of the present study may provide an important basis for diagnosing CAD patients, and provide new therapeutic targets for CAD.  相似文献   
69.
针对提升机滚筒筒壳开裂的内因和外因进行了简要分析。根据现场使用情况,对于不同开裂情况采用不同解决方案,并提出相关预防措施。  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