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排序方式: 共有202条查询结果,搜索用时 15 毫秒
1.
从电机性能和编码器性能两方面分析了对巡线机器人行走电机温度进行实时检测的必要性.提出了一种有刷直流电机发热模型及传热模型,并通过模型成功计算出电机绕组与外界环境的温度差值.介绍了巡线机器人行走电机温度的检测控制系统及温度传感器的安装结构.采用温度传感器DS18B20进行温度检测,用地面基站人机交互平台实时显示机器人现场运行过程中行走电机温度.在机器人控制程序中设定温度预设值,将所测得温度值与预设温度上限值进行比较,当所测得温度值高于上限值时,机器人将停止正在进行的运动,直至所测得温度低于预设值.以此实现机器人的智能控制.同时,基于高斯-马尔科夫的假设建立了温度传感器的一元线性回归模型,并根据假设采用了基于最小二乘法原理的方法对温度的测量值进行有效的修正. 相似文献
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车用空调器压缩机前端板铸件壳型铸造工艺实践 总被引:1,自引:0,他引:1
对前端板铸件壳型铸造中存在的铸造缺陷,采用优化浇注系统,对铁水进行二次孕育处理,调整碳当量控制在3.90%~4.15%,硅含量降低0.15%~0.20%,使产品抗拉强度≥270MPa,硬度(HB)为187~241,满足用户要求。 相似文献
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研究了多孔硅质岩矿粉掺入到普通硅酸盐水泥中对水泥性能的影响.认为多孔硅质岩矿粉是一种良好的天然活性混合材料,可用于制作掺混合材料的硅酸盐水泥或复合硅酸盐水泥. 相似文献
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Yuling MA Chaoran CUI Jun YU Jie GUO Gongping YANG Yilong YIN 《Frontiers of Computer Science》2020,14(5):145313
In higher education, the initial studying period of each course plays a crucial role for students, and seriously influences the subsequent learning activities. However, given the large size of a course’s students at universities, it has become impossible for teachers to keep track of the performance of individual students. In this circumstance, an academic early warning system is desirable, which automatically detects students with difficulties in learning (i.e., at-risk students) prior to a course starting. However, previous studies are not well suited to this purpose for two reasons: 1) they have mainly concentrated on e-learning platforms, e.g., massive open online courses (MOOCs), and relied on the data about students’ online activities, which is hardly accessed in traditional teaching scenarios; and 2) they have only made performance prediction when a course is in progress or even close to the end. In this paper, for traditional classroomteaching scenarios, we investigate the task of pre-course student performance prediction, which refers to detecting at-risk students for each course before its commencement. To better represent a student sample and utilize the correlations among courses, we cast the problem as a multi-instance multi-label (MIML) problem. Besides, given the problem of data scarcity, we propose a novel multi-task learning method, i.e., MIML-Circle, to predict the performance of students from different specialties in a unified framework. Extensive experiments are conducted on five real-world datasets, and the results demonstrate the superiority of our approach over the state-of-the-art methods. 相似文献
7.
Jiawei Zhu Shaobin Guo Gongping Liu Zhengkun Liu Zhicheng Zhang Wanqin Jin 《American Institute of Chemical Engineers》2015,61(8):2592-2599
To accelerate the commercial application of mixed‐conducting membrane reactor for catalytic reaction processes, a robust mixed‐conducting multichannel hollow fiber (MCMHF) membrane reactor was constructed and characterized in this work. The MCMHF membrane based on reduction‐tolerant and CO2‐stable SrFe0.8Nb0.2O3‐δ (SFN) oxide not only possesses a good mechanical strength but also has a high oxygen permeation flux under air/He gradient, which is about four times that of SFN disk membrane. When partial oxidation of methane (POM) was performed in the MCMHF membrane reactor, excellent reaction performance (oxygen flux of 19.2 mL min?1 cm?2, hydrogen production rate of 54.7 mL min?1 cm?2, methane conversion of 94.6% and the CO selectivity of 99%) was achieved at 1173 K. And also, the MCMHF membrane reactor for POM reaction was operated stably for 120 h without obvious degradation of reaction performance. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2592–2599, 2015 相似文献
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Xi Chen Guining Chen Guozhen Liu Gongping Liu Wanqin Jin 《American Institute of Chemical Engineers》2022,68(8):e17688
Mixed-matrix membranes (MMMs), judiciously combining processability of polymer and remarkable separation performance of nanofillers, have been extensive pursuits for molecular separation process. Permeability matching between filler and polymer is one of the necessary requisites to desirable mixed-matrix effect. Considering the superior molecular sieving effect of UTSA-280 metal-organic frameworks on C2H4 and C2H6, here, we report two types of UTSA-280/6FDA-polyimide MMMs toward C2H4/C2H6 separation. The molecular sieving effect of UTSA-280 endowed 6FDA-DAM:DABA(3:2) membrane with simultaneous improvements in C2H4 permeability and C2H4/C2H6 selectivity. Optimally, when the filler reached 21.80 wt%, C2H4 permeability and C2H4/C2H6 selectivity was increased to 6.49 Barrer (by 15%) and 4.94 (by 32%), respectively. On the contrary, UTSA-280/6FDA-DAM MMMs showed undesirable mixed-matrix effect that C2H4 permeability decreased meanwhile C2H4/C2H6 selectivity nearly kept at polymeric pristine membrane level. It was found that permeability matching between two phases was responsible to these opposite mixed-matrix effects. More specifically, UTSA-280 had a relatively low gas permeability so that it required a less permeable polymeric matrix like 6FDA-DAM:DABA(3:2) to exert its molecular sieving effect. Furthermore, the optimal-matching 6FDA-matrix in permeability with UTSA-280 fillers was predicted by theoretical model. This work not only reports improving C2H4/C2H6 separation performance via mixed-matrix formulation, but also emphasizes the importance of permeability matching between polymer and filler to realize the mixed-matrix effect. 相似文献
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