全文获取类型
收费全文 | 134900篇 |
免费 | 8080篇 |
国内免费 | 4249篇 |
专业分类
电工技术 | 6967篇 |
技术理论 | 8篇 |
综合类 | 12341篇 |
化学工业 | 9667篇 |
金属工艺 | 5530篇 |
机械仪表 | 14840篇 |
建筑科学 | 29623篇 |
矿业工程 | 4104篇 |
能源动力 | 3286篇 |
轻工业 | 5368篇 |
水利工程 | 3902篇 |
石油天然气 | 4279篇 |
武器工业 | 1590篇 |
无线电 | 8682篇 |
一般工业技术 | 14103篇 |
冶金工业 | 3358篇 |
原子能技术 | 738篇 |
自动化技术 | 18843篇 |
出版年
2024年 | 489篇 |
2023年 | 1322篇 |
2022年 | 2220篇 |
2021年 | 2825篇 |
2020年 | 3173篇 |
2019年 | 2460篇 |
2018年 | 2420篇 |
2017年 | 3091篇 |
2016年 | 3523篇 |
2015年 | 3793篇 |
2014年 | 9563篇 |
2013年 | 7749篇 |
2012年 | 9529篇 |
2011年 | 10175篇 |
2010年 | 8608篇 |
2009年 | 8929篇 |
2008年 | 8079篇 |
2007年 | 9631篇 |
2006年 | 8086篇 |
2005年 | 7121篇 |
2004年 | 5756篇 |
2003年 | 5387篇 |
2002年 | 4298篇 |
2001年 | 3641篇 |
2000年 | 2998篇 |
1999年 | 2327篇 |
1998年 | 1912篇 |
1997年 | 1618篇 |
1996年 | 1367篇 |
1995年 | 1081篇 |
1994年 | 894篇 |
1993年 | 613篇 |
1992年 | 498篇 |
1991年 | 418篇 |
1990年 | 264篇 |
1989年 | 265篇 |
1988年 | 210篇 |
1987年 | 154篇 |
1986年 | 92篇 |
1985年 | 105篇 |
1984年 | 131篇 |
1983年 | 86篇 |
1982年 | 98篇 |
1981年 | 38篇 |
1980年 | 37篇 |
1979年 | 28篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1971年 | 9篇 |
1959年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
71.
Despite the apparent maturity of the learning design field, and the variety of tooling available to support it, adoption among the teacher community (one of its alleged main targets) is still low. There is a lack of research on teachers' perception and use of different technological learning design tools, as existing evaluations are often restricted to a single tool. In order to explore whether there are common factors hampering teacher adoption, and which tool features might appeal to different teachers, more studies involving multiple authoring tools are needed. This paper provides a first step in this direction, describing a mixed methods study performed around a professional development workshop with 18 university teachers from multiple disciplines. This workshop exposed teachers to two different authoring tools (WebCollage and EDIT2), as they learned to create computer-supported collaborative learning (CSCL) designs and implement them. The findings of our interpretive study (which included questionnaires, observations, or group discussion recordings) support the idea that there is no single tool or set of features that are globally perceived as better, although our evidence also highlights certain factors as important for participant teachers – amongst others, the integration of learning designs with the ICT platforms for enactment, as well as with other tools that they already use in their everyday practice. 相似文献
72.
《Expert systems with applications》2014,41(8):3726-3735
Defining appropriate pricing strategy for smart environment is important and complex task at the same time. It holds the primal fraction in Demand Response (DR) program. In our work, we devise an incentive based smart dynamic pricing scheme for consumers facilitating a multi-layered scoring rule. The proposed strategy characterizes both incentive based DR and price based DR programs facilities. This mechanism is applied between consumer agents (CA) to electricity provider agent (EP) and EP to Generation Company (GENCO). Based on the Continuous Ranked Probability Score (CRPS), a hierarchical scoring system is formed among these entities, CA–EP–GENCO. As CA receives the dynamic day-ahead pricing signal from EP, it will schedule the household appliances to lower price period and report the prediction in a form of a probability distribution function to EP. EP, in similar way reports the aggregated demand prediction to GENCO. Finally, GENCO computes the base discount after running a cost-optimization problem. GENCO will reward EP with a fraction of discount based on their prediction accuracy. EP will do the same to CA based on how truthful they were reporting their intentions on device scheduling. The method is tested on real data provided by Ontario Power Company and we show that this scheme is capable to reduce energy consumption and consumers’ payment. 相似文献
73.
74.
MgO/Ni系梯度功能材料的设计与制备 总被引:11,自引:0,他引:11
对MgO/Ni系梯度功能材料(FGM),分别用实验和微观力学模型测定和计算了用于热应力缓和设计的各物性参数。讨论了两种结果之间存在差异的原因。用有限元方法模拟了制备过程中FGM的热应力,得到MgO/Ni系FGM的综合设计准则。按设计结果进一步调整粉末工艺性质,成功地烧制出MgO/Ni系FGM。 相似文献
75.
液氨贮存设计分析 总被引:3,自引:0,他引:3
马朝玲 《硫磷设计与粉体工程》2004,(1):20-22
氨是生产含氮肥料及尿素的基本原料,为确保原料供应,必须设置其贮存设施。介绍了常温中压、降温低压和低温常压三种不同的液氨贮存工艺及其特点,并以某大型氨站设计为例,分析了液氨贮存工艺流程、主要设备、材料的选型和工艺参数的确定。 相似文献
76.
隧道式锚碇的变形破坏机制涉及到结构与围岩的协同作用问题。以华丽高速公路金安金沙江悬索桥两岸隧道锚变形破坏机制为研究对象,利用工程类比法评价了其稳定性控制要素,设计了超载数值试验。根据塑性区的扩展过程确定了施工安全监测和需要采取预加固的重点部位,确定了隧道锚围岩的破坏模式。根据锚面监测点位移由mm到cm量级突变确定的两岸锚岩系统极限荷载均为6~8倍设计缆力,则锚岩系统的设计承载力取3倍设计缆力下变形安全是有保障的。丽江岸塑性区在10 P下贯通;华坪岸塑性区在14 P下贯通。设计缆力作用下,丽江岸锚碇最大位移1.5 mm、围岩1.2 mm、地表0.5 mm;华坪岸锚碇最大位移1.7 mm、围岩1.5 mm、地表0.7 mm,其响应顺序为后锚面监测点前锚面监测点锚碇中间岩体地表点,可作为后期结构及围岩安全监测布点和预警的参考,也证明当前设计缆力下变形和强度均是安全的。 相似文献
77.
The HUB-CI model is investigated in a telerobotic system in a client/server network to manage the lifecycle of engineering design and prototyping. The purpose of this platform is to support collaborative engineering design and proof of concept to enhance distributed team collaboration and resource utilization. The suggested platform is exemplified in two collaboration support tools and a physical prototyping platform. Structured Co-Insight Management is developed to support innovative idea exchanges and the consensus decision-making during the design process. Conflict/error detection management helps preventing conflicts and errors during the lifecycle of design and development. Physical collaboration over the network occurs when a team controls the telerobot operation during prototyping and testing in design cycles. A pilot system is implemented with a group project for the design of an electronic circuit (including both hardware and software designs). The functional assessment method is used to compare this platform to other collaborative design tools. The system presented offers unique qualitative advantages as an integrated collaboration support system. 相似文献
78.
介绍了氟化氢吸收原理、流程 ,国内外氟化氢吸收设备的选型 ,满足工艺要求的穿流栅板塔的设计计算及应用。 相似文献
79.
刘峰 《硫磷设计与粉体工程》2004,(5):15-18
贮仓是许多工业过程中的常用设备,起拱是贮仓使用时常出现的故障,如何解决起拱问题是贮仓设计的关键,除常采取增大仓壁倾角、设置破拱装置等方法外,设计成曲线贮仓也是行之有效的措施之一。分析了指数曲线贮仓的工作原理和特点,建立了仓壁指数曲线方程,阐述了设计步骤与注意事项,并举例说明。 相似文献
80.
介绍了几种胶辊用混炼硅橡胶的配制,包括低硬度胶辊用混炼硅橡胶、低环硅氧烷含量的胶辊用混炼硅橡胶、送纸胶辊用混炼硅橡胶及工业胶辊用混炼硅橡胶的配制。 相似文献