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排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
Wenyun Yang Qiwei Hu Guanyi Qiao Liang Zha Shunquan Liu Jingzhi Han Honglin Du Yan Zhang Yingchang Yang Changsheng Wang 《中国稀土学报(英文版)》2019,37(10):1102-1107
In this work, we report the tuning effect of the Si substitution on the magnetic and high frequency electromagnetic properties of R2Fe17 compounds and their paraffin composites. It is found that the introduction of Si can remarkably improve the magnetic and electromagnetic properties of the R2Fe17 compounds, making the R2Fe17–xSix-paraffin composites excellent microwave absorption materials (MAMs). By introducing the Si element, their saturation magnetizations decrease slightly, while much higher Curie temperatures are obtained. Furthermore, better impedance match is reached due to the decrease of the high-frequency permittivity ε′ by about 40%–50%, which finally enhances the performance of the microwave absorption. The peak frequency (fRL) of the reflection loss (RL) curve moves toward high frequency domain and the qualified bandwidth (QB, RL ≤ ?10 dB) increases remarkably. The maximum QB of 3.3 GHz (12.0–15.3 GHz) is obtained for the Sm1.5Y0.5Fe15Si2-paraffin composite (d = 1.0 mm) and the maximum RL of ?53.6 dB is achieved for Nd2Fe15Si2-paraffin composite (d = 2.2 mm), both surpassing most of the reported MAMs. Additionally, a distinguished dielectric microwave absorption peak is observed, which further increases the QB in these composites. 相似文献
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M. Ronen 《Journal of Computer Assisted Learning》1995,11(3):141-156
Abstract This article presents a study of a large scale incorporation of one data acquisitionsystem into physics teaching in Israel. By 1994 about 30% of the schools throughout the country used the V-scope, a 3-D multibody motion tracing system, in their lab programme. The views and reactions of post-training teachers, experienced teachers and students on various aspects of using the system are described, analysed and compared. 相似文献
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Cyber-physical production systems enable adaptivity and flexibility when manufacturing customized products in small batches. Due to varying routes and a high variance of workpieces, material flows in cyber-physical production systems can get highly complex, which can lead to physically induced disturbances that can result in accidents or decreased throughput and high costs. This issue can be addressed by applying a physics engine to simulate the physical interaction between workpieces and the material handling systems during the operation. Connecting such a digital model to a real material handling system in order to derive simulation-based decision support leads to the concept of digital twins. To date, few practical implementations of digital twins in manufacturing outside the machine tool domain were reported. Therefore, this paper describes the modeling and the subsequent implementation of an integrated system that consists of a real material handling system and its digital twin, based on physics simulation. A practical use case demonstrates the versatile advantages of the implemented solution for a manufacturing system with respect to the three digital twin functions prediction, monitoring and diagnosis. 相似文献
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Teaching and learning through Virtual Reality(VR) is an emerging technology in the last few years. In this article, the development and use of a VR based teaching–learning system for crystal structures are discussed. The VR system is designed as a lab environment where a user can do experiments related to crystal structures. The VR system is designed in Unity,1 and Oculus Rift S2 is used as a VR headset. Currently, the system consists of three phases; in the first phase user can visualize the crystal lattice structures, wherein the second one a user can visualize the light interaction with the crystal lattice structure using a virtual torch ray. The third phase is the X-ray Diffraction (XRD) experiment. In this phase, users can perform the XRD experiment in the lab environment by taking a random crystal from a crystal dispenser machine and placing it in the X-ray machine which identifies the chosen crystalline material and analyses the unit cell. The incident ray colour changes when there is a peak found in the crystal for a better understanding of the user. There is also an interactive display where users can increase/decrease the angles of the radiation and also lock and unlock the experiment to view the diffraction plot for the crystal structure. In many cases, it was found that XRD and the crystal structure is available in the course syllabus but there are no experiments to enhance their learning. Therefore an experiment with 39 participants was performed where the maximum participants are new to crystallography. The study was conducted in two phases; in the first phase, participants are asked to watch video tutorials of the topic followed by questionnaires; in the second phase participants are asked to do the VR based experiment and followed by questionnaires related to overall study and experiment. From the analysis of the study we found that everyone found VR based teaching methods are better than traditional book/video studies. Study results give an average score of 56.74% in comparison to VR based learning approach with an average score of 93.81%. Participants who took part in the experiment found the experience interactive and motivating and found it helpful to learn elusive concepts, which can be learned when simulated. For example, one participant wrote: “The VR experience was surreal and was easy to control. Lucid user experience. Got a view of XRD like never seen before”. 相似文献
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片理颗粒的碰撞在工业生产中占有很大比重,但是由于其混合碰撞的过程不可视,这就使得对它的观察和研究非常困难。文章采用图形引擎OSG和物理引擎Bullet,设计了片理颗粒混合碰撞仿真系统。操作人员通过使用本系统,可以获得重要参数,以便对实际生产进行指导。本系统通过解决图形场景中3DS模型和片理颗粒的控制、碰撞检测、OSG图形引擎与Bullet物理引擎结合以及场景渲染优化等关键技术问题,最后实现仿真模拟程序。操作人员可以通过对系统的信息交互,从而可以观察相应数据所产生的颗粒混合碰撞的过程。 相似文献
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以大学物理开放实验课程为例,针对当前高校物理开放性实验网络选课系统在辅助教学方面的一些不足,提出改进措施,设计优化型网络选课系统,分析系统的功能和特点,并对该系统的几个功能模块进行简单介绍。 相似文献