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   24604篇
  免费   2858篇
  国内免费   1435篇
电工技术   3742篇
综合类   3010篇
化学工业   388篇
金属工艺   412篇
机械仪表   1750篇
建筑科学   987篇
矿业工程   542篇
能源动力   184篇
轻工业   574篇
水利工程   364篇
石油天然气   331篇
武器工业   296篇
无线电   7280篇
一般工业技术   1546篇
冶金工业   247篇
原子能技术   209篇
自动化技术   7035篇
  2024年   45篇
  2023年   317篇
  2022年   446篇
  2021年   546篇
  2020年   536篇
  2019年   374篇
  2018年   346篇
  2017年   529篇
  2016年   631篇
  2015年   845篇
  2014年   1434篇
  2013年   1334篇
  2012年   1837篇
  2011年   2079篇
  2010年   1687篇
  2009年   1796篇
  2008年   1889篇
  2007年   2248篇
  2006年   2011篇
  2005年   1781篇
  2004年   1336篇
  2003年   1119篇
  2002年   837篇
  2001年   674篇
  2000年   489篇
  1999年   337篇
  1998年   217篇
  1997年   185篇
  1996年   169篇
  1995年   186篇
  1994年   136篇
  1993年   97篇
  1992年   63篇
  1991年   59篇
  1990年   52篇
  1989年   46篇
  1988年   37篇
  1987年   20篇
  1986年   18篇
  1985年   19篇
  1984年   22篇
  1983年   13篇
  1982年   16篇
  1981年   8篇
  1980年   9篇
  1979年   9篇
  1978年   3篇
  1977年   3篇
  1959年   4篇
  1955年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Renewing undergraduate education in the chemical sciences to foster creativity using research, visualization and connectivity resources has substantial benefits, but requires changes in the curriculum and teaching methodology as well as in academic teaching and human resource conventional policies.  相似文献   
53.
54.
The digital cushion is an essential part of maintaining a healthy foot, working to dissipate foot strike and body weight forces and lameness from claw horn disruption lesions. Despite the importance of the digital cushion, little is known about the basic anatomy, adipocyte morphology, and fatty acid composition in relation to age, limb position, and body condition score. In total, 60 claws (from 17 cows) were selected and collected from a herd, ensuring that body condition score data and computed micro-tomography were known for each animal. Digital cushion tissue underwent histological staining combined with stereology, systematic random sampling, and cell morphology analysis, in addition to lipid extraction followed by fatty acid analysis. The results describe digital cushion architecture and adipocyte sizes. Adipocyte size was similar across all 4 claws (distal left lateral and medial and distal right lateral and medial) and across the ages (aged 2–7 yr); however, animals with body condition score of 3.00 or more at slaughter had a significantly increased cell size in comparison to those with a score of less than 2.50. Of 37 fatty acid methyl esters identified, 5 differed between either the body condition score or different age groups. C10:0 capric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, and C20:0 arachidic acid percentages were all lesser in lower body condition score cows, whereas C22:1n-9 erucic acid measurements were lesser in younger cows. Saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid percentages were not altered in the different claws, ages, or body condition score groups. Triglyceride quantities did not differ for claw position or age but had decreased quantities in lower body condition score animals. Digital cushion anatomy, cellular morphology, and fatty acid composition have been described in general and also in animals with differing ages, body condition scores, and in the differing claws. Understanding fat deposition, mobilization, and composition are essential in not only understanding the roles that the digital cushion plays but also in preventing disorders and maintaining cattle health and welfare.  相似文献   
55.
数字技术环境下景观规划设计教学改革与实践   总被引:1,自引:0,他引:1       下载免费PDF全文
李哲  成玉宁 《风景园林》2019,26(S2):67-71
设计创新能力培养已成为21世纪风景园林学规划设计教学核心,在此背景下,由知识传输导向的教学模式正逐步转变为由设计与科研并肩引领知识增长的教学模式,数字化景观规划设计教学体系与方法成为当代风景园林教育亟待充实并应用的重要内容。立足风景园林教学前沿,基于对当代风景园林规划设计教育的系统把握,以东南大学风景园林专业教学实践为例,提出整合数字景观技术平台,构建“浸入式”数字技术教学环境,实现数字平台与教学体系的协同创新;继而针对传统教学方法局限,利用数字化教学平台进行“耦合教学法”创新实践,加强实证性知识体系集成融合,实现风景园林规划设计课程教学模式的系统探索与实践。  相似文献   
56.
数字经济时代,新技术、新产业、新业态、新模式加速孕育,网络市场竞争态势愈加复杂、多变,监管创新成为重要课题。网络市场监管工作应当确立稳定、可预期的监管原则,并落实好包容审慎、事中事后监管、协同监管等原则;对关系到国家安全、社会稳定和公众生命健康等底线性问题,监管不能缺位,而应继续严格审查监管。从创新监管原则的宏观研究,以及大数据监管、提升电子取证能力等监管手段的具体研究等维度,对监管创新进行了深度思考。  相似文献   
57.
Live-stream shopping is experiencing unprecedented growth. However, research in live-stream commerce is in its infancy. The current study integrates uses and gratifications, perceived network size, perceptions of digital celebrities, and experience-focused shopping orientation to clarify motivations for live-stream shopping. Accordingly, the current study used a questionnaire to collect data from 339 Chinese consumers and structural equation modeling to analyze data in AMOS 24. In this study, individuals were motivated by gratifications that were (1) hedonic (perceived enjoyment), (2) utilitarian (self-presentation), and (3) social (social presence and interaction). Moreover, perceived network size significantly predicted perceived enjoyment, social interaction, social presence, and utility. In addition, experience-focused shopping orientation mediated the relationships among perceived enjoyment, self-presentation, social interaction, and live-stream shopping intentions. Finally, the mediating roles of the perceptions of digital celebrities in the relationships of perceived network size with perceived utility, perceived engagement, social interaction, social presence, and self-presentation were confirmed.  相似文献   
58.
Illite is a group of clay minerals that are expected to be widely used in catalyst fabrication, radioactive element adsorption, and so forth, due to its excellent adsorption properties. However, the shape control limitation of the illite product should be overcome to maximize its utilization and properties. We herein propose additive manufacturing (AM) as one of the best solutions to solve this structural drawback. Digital light processing (DLP) technology with the film-type of the material supplying system was adapted instead of the general vat-type DLP system to increase illite printability. The photo-curability and printability of illite-contained photocurable suspension were optimized. The color effect due to different ferric oxide content in yellow- and white-illite which influence the photopolymerization process also adjusted thoroughly. White illite showed better photo-curability and could be increased solid loading than yellow illite. The defect-free illite products with three-dimensional complex structures, which cannot be produced by typical ceramic processes, were obtained by DLP technology for both yellow- and white-illite after sintering at 1100°C. The overcoming of shape control limitation of illites by ceramic AM proved in this study has excellent potential for expanding illite utilities in various applications.  相似文献   
59.
“数字信号处理”的经典课程体系以“系统”为中心,以离散时间傅立叶变换、z变换和离散傅立叶变换为分析工具,以滤波器设计为目的,注重定理和公式推导及其性质分析,很难让学生建立一个形象的、完整统一的知识体系框架。本文从几何视角将 “系统”化和“代数”化的经典课程体系重构为面向“信号”的“几何”知识体系,从而提升学生对本质问题的“洞察力”,帮助学生建立系统的知识体系。  相似文献   
60.
落实立德树人,实现三全育人,将思政融入到《数字电子技术》这门专业课程中,培养学生专业知识的同时,引导学生树立良好的人生观和价值观。通过重构本校的数字电子技术课程内容,挖掘思政元素,并润物细无声般融入到数字电子技术的教学改革中,并通过实际的案例讲解具体融入过程。  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