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   36192篇
  免费   4452篇
  国内免费   2146篇
电工技术   5314篇
技术理论   4篇
综合类   5450篇
化学工业   1579篇
金属工艺   1005篇
机械仪表   2672篇
建筑科学   4310篇
矿业工程   928篇
能源动力   819篇
轻工业   573篇
水利工程   1045篇
石油天然气   1012篇
武器工业   594篇
无线电   5266篇
一般工业技术   2656篇
冶金工业   1706篇
原子能技术   303篇
自动化技术   7554篇
  2024年   93篇
  2023年   548篇
  2022年   1039篇
  2021年   1207篇
  2020年   1406篇
  2019年   1126篇
  2018年   878篇
  2017年   1241篇
  2016年   1420篇
  2015年   1537篇
  2014年   2811篇
  2013年   2233篇
  2012年   3008篇
  2011年   3268篇
  2010年   2486篇
  2009年   2433篇
  2008年   2191篇
  2007年   2481篇
  2006年   2049篇
  2005年   1793篇
  2004年   1436篇
  2003年   1206篇
  2002年   1012篇
  2001年   816篇
  2000年   585篇
  1999年   488篇
  1998年   334篇
  1997年   288篇
  1996年   228篇
  1995年   193篇
  1994年   137篇
  1993年   97篇
  1992年   101篇
  1991年   60篇
  1990年   57篇
  1989年   66篇
  1988年   56篇
  1987年   23篇
  1986年   16篇
  1985年   18篇
  1984年   20篇
  1979年   16篇
  1966年   19篇
  1962年   14篇
  1959年   21篇
  1958年   19篇
  1957年   20篇
  1956年   16篇
  1955年   19篇
  1954年   16篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
1.
在大类培养改革背景下,基于“电工学实验”开放式实践教学体系现状进行了“电工学实验”混合教学模式的研究,建立了“微课”资源并通过新型教学平台进行推送,确立了完备的混合教学模式应用机制并在部分专业进行了试点,通过分析试点调查数据得出混合教学模式具有在实验教学中提高学生学习效率、激发学生学习动力、促进学生个性发展、培养学生实践应用能力的优势,是落实创新应用型人才培养目标的重要举措。  相似文献   
2.
为提高本科毕业设计指导工作效率和毕业论文质量,本文基于雷达工程专业特点建立了“导师主导--研究生辅助--本科生合作”的多层次、模块化、场景化指导模式。该模式以导师为核心、科研小组和学员合作为辅助,全方位全过程保障本科毕设工作。实践表明,该模式可以有效提高指导工作效率和本科毕业设计质量,学生专业素养和实践能力显著提升。本文对电子类专业本科毕设指导具有重要借鉴意义。  相似文献   
3.
研究基于“半翻转”教学模式的线上教学评价指标体系,包括课前活动开展、课中教学活动设计、课后任务以及基于此过程中的评价指标体系设计。最后通过层次分析法设计评价指标权重,设计评价算法得到动态评价结果。该评价指标体系应用在本专业“数据结构与算法”课程中,并得到良好的应用效果。  相似文献   
4.
为了更加真实、直观地呈现智能变电站的运行整体结构,构建基于VR技术的智能变电站运行仿真培训系统。该系统通过5个模块协同完成智能变电站运行仿真培训,结合实际变电站的设备情况,采用二维纹理映射方法完成变电站设备仿真建模;系统利用虚拟现实交互模块呈现培训场景,参与培训人员能够通过人机交互设备,实现场景漫游和相关培训内容操作。测试结果表明:该系统能够较好地模拟出智能变电站的实际运行情况,参与培训的人员可以身临其境地完成整个变电站的巡视,更真实、直观地呈现智能变电站的整体状态。  相似文献   
5.
The gas purging states affect electricity output and energy storage capacity of unitized regenerative fuel cells. In this study, a model of unitized regenerative fuel cell is established. Cell voltages and operating temperatures influences on the dynamic distribution of thermal fluid during purging process and the discharge of residual liquid water in electrolytic cell mode are investigated. The motivation of the present study is better understanding the gas purging characteristics and its effect on reaction behaviors of unitized regenerative fuel cells. Simulation results reveal a significant influence of purging gas temperature on the water flooding and a great effect of operating voltage on the water diffusion. The operating temperature of electrolytic cell model almost has little effect on purging results at different cell temperature and the same purging gas temperature. When the purging gas temperature is changed, higher temperatures of cell and purging gas facilitate liquid water discharging out from the cell regions. In cell water flooding situation, when having large liquid content, the purging gas has little effects on the water expelling process.  相似文献   
6.
According to the International Energy Agency, only a small part of the full potential of biomass energy is currently used in the world. The annual amount of agricultural waste in the Russian Federation is estimated at about 152 million tons, and the energy potential of animal waste is 201 PJ/year. Anaerobic digestion is an efficient method of converting organic waste into renewable energy sources. Previously, the positive effect of pretreatment of various organic feedstocks in vortex layer apparatus (VLA) on the characteristics of anaerobic digestion and energy efficiency was shown. Currently, there is a significant interest in the world in obtaining biohydrogen from organic waste using the dark fermentation (DF) process. During pretreatment in the VLA, the iron working bodies are abraded and iron particles are introduced into the feedstock of the DF reactor. This may have a positive effect on the production rate and yield of hydrogen, which has not been previously studied. This work is aimed at evaluating the possibility of using the VLA as a method for pretreatment of a dark fermentation feedstock for the intensification of biohydrogen production. To achieve this goal, an experimental setup was constructed. It consisted of a 45 L DF reactor, a VLA and a process control system to collect data on the DF process parameters every 5 min. At a hydraulic retention time in the DF reactor of 24 h and in the VLA of 30 s, the hydrogen content in the biogas increased from 51.1% to 52.2%. At the same time, the pH increased from 3.85 to 4.8–4.9, and the hydrogen production rate increased by 16% to 1.941 L/(L day). The hydrogen yield was 80.9 ml/g VS. Thus, pretreatment of the feedstock in VLA can be an effective way to intensify the DF process; however, further study of the VLA operating modes is required in order to optimize the concentrations of iron particles introduced into the feedstock for the most efficient continuous production of dark fermentative biohydrogen.  相似文献   
7.
This paper considers the shared path following control of an unmanned ground vehicle by a single person. A passive measure of human intent is used to blend the human and machine inputs in a mixed initiative approach. The blending law is combined with saturated super-twisting sliding mode speed and heading controllers, so that exogenous disturbances can be counteracted via equivalent control. It is proven that when the proposed blending law is used, the combined control signals from both the human and automatic controller respect the actuator magnitude constraints of the machine. To demonstrate the approach, shared control experiments are performed using an unmanned ground vehicle, which follows a lawn mower pattern shaped path.  相似文献   
8.
While exercise training (ET) is an efficient strategy to manage obesity, it is recommended with a dietary plan to maximize the antiobesity functions owing to a compensational increase in energy intake. Capsiate is a notable bioactive compound for managing obesity owing to its capacity to increase energy expenditure. We aimed to examine whether the antiobesity effects of ET can be further enhanced by capsiate intake (CI) and determine its effects on resting energy expenditure and metabolic molecules. Mice were randomly divided into four groups (n = 8 per group) and fed high-fat diet. Mild-intensity treadmill ET was conducted five times/week; capsiate (10 mg/kg) was orally administered daily. After 8 weeks, resting metabolic rate and metabolic molecules were analyzed. ET with CI additively reduced the abdominal fat rate by 18% and solely upregulated beta-3-adrenoceptors in adipose tissue (p = 0.013) but did not affect the metabolic molecules in skeletal muscles. Surprisingly, CI without ET significantly increased the abdominal fat rate (p = 0.001) and reduced energy expenditure by 9%. Therefore, capsiate could be a candidate compound for maximizing the antiobesity effects of ET by upregulating beta-3-adrenoceptors in adipose tissue, but CI without ET may not be beneficial in managing obesity.  相似文献   
9.
采用数值模拟软件对××大学科技馆某小型会议室进行数值模拟,以实际测量的数据为边界条件,建立合适的数学和物理模型,得到温度场、速度场以及空气品质场等模拟结果,通过对模拟结果的对比分析,得到了最佳的气流组织设计方案,相关结论可以为室内气流组织方案设计与优化提供参考依据。  相似文献   
10.
In lead optimization, protein crystallography is an indispensable tool to analyze drug binding. Binding modes and non-covalent interaction inventories are essential to design follow-up synthesis candidates. Two protocols are commonly applied to produce protein–ligand complexes: cocrystallization and soaking. Because of its time and cost effectiveness, soaking is the more popular method. Taking eight ligand hinge binders of protein kinase A, we demonstrate that cocrystallization is superior. Particularly for flexible proteins, such as kinases, and larger ligands cocrystallization captures more reliable the correct binding pose and induced protein adaptations. The geometrical discrepancies between soaking and cocrystallization appear smaller for fragment-sized ligands. For larger flexible ligands that trigger conformational changes of the protein, soaking can be misleading and underestimates the number of possible polar interactions due to inadequate, highly impaired positions of protein amino-acid side and main chain atoms. Thus, if applicable cocrystallization should be the gold standard to study protein–ligand complexes.  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