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排序方式: 共有178条查询结果,搜索用时 140 毫秒
1.
《Ceramics International》2022,48(12):16730-16736
Recently, all-inorganic cesium lead-halide perovskites have shown their promise for light emission applications, due to the excellent optical performance. Herein, we report that the initially nonphosphorescent undoped lead-halide Cs4PbBr6 single crystals (SCs) exhibit an ultralong phosphorescence emission under X-ray excitation at low temperatures. It is shown that the dramatic change has been taken place in radioluminescence spectra and the broad-band emission gradually appeared with the decrease of temperature. Below 210 K, the radioluminescence spectra can be deconvoluted into one narrow peak located at 530 nm and two broad peaks centered at 595 nm and 672 nm respectively. Subsequently, the time-dependent radioluminescence spectra in undoped lead-halide Cs4PbBr6 SCs were investigated. The ultralong phosphorescence emission can persist over 120 min at 70 K. We consider that ultralong phosphorescence originates from defect-related emission. To the best of our knowledge, our finding is the first time that undoped Cs4PbBr6 SCs exhibit the phosphorescence emission, which will offer a paradigm to motivate revolutionary applications on perovskite. 相似文献
2.
二氧化钛是一种具有半导体性质的光催化剂,可利用低能量的紫外光照射,进行有机污染物光催化的分解反应。用溶胶凝胶法合成Ti O2,并在其中掺杂Fe3+。在玻璃片上制备了Ti O2薄膜,并用此薄膜对甲基橙在紫外光和可见光下进行降解。发现经过掺杂的薄膜在450℃处理后,不会对Ti O2结构产生明显的影响,但可大大提高Ti O2在紫外光照射下对污染物的分解效率,并且大大拓展了Ti O2对可见光的响应范围。 相似文献
3.
Gerrit K. Janssens An Caris Katrien Ramaekers 《Expert systems with applications》2009,36(3):5987-5991
Congestion on roads leads to uncertainty in travel times, which is important in delivery of goods, especially in a business environment where high levels of customer service are expected. Delivery periods to customers might be constrained by time windows, which makes the scheduling and routing of vehicles from the supplier’s side more difficult. Operations Research methods turn into heuristics for this type of application. But when, on top, uncertainty on travel times are the case, any hope of a simple and well-performing heuristic is lost. This study applies a methodology in which a heuristic is used to find a solution for scheduling and routing under deterministic travel times and, by means of simulation, though the use of Time Petri nets evaluates the sensitivity of the solution to uncertainties in travel times from one customer to the next in a route. 相似文献
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《Advanced Powder Technology》2019,30(10):2240-2250
The monitoring of tiny particles in multiphase pipe flow is widely encountered in industry. In this paper, the identification and characterization of solid particles suspended in sand-water flow were developed based on vibration multi-sensor approaches. Verification experiments were conducted, and good agreement was found between the concentrations (0–0.1 wt% with an interval of 0.02 wt%) of varisized sands (from 86 to 180 μm) and the monitored vibration signal characteristics by multi-sensor approaches. A quadratic relationship between the particle concentration and vibration energy was obtained. In sand-carrying flow measurement experiments, the sand’s characteristic frequency bands were found at 22–23.6 kHz and 24.8–26.6 kHz. Additionally, the sand particle identification effect was evaluated from two positions at bends, that is, the outer wall of the 45-degree bend on the elbow and the exit of the 90-degree bend. Compared with these two monitor positions, the sand vibration energy from the outlet of the elbow had a higher signal-to-noise ratio with obvious energy variations. In addition, the accuracies of the detected sand vibration features were mutual confirmation. Consequently, the above methods are applicable for little solid detection in sand-water flow, which lays the foundation for particles monitoring in the complexed multiphase flow. 相似文献
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研究采用多弧离子镀技术镀膜时,电弧放电阶段中电弧弧斑的运动对后续膜层质量与靶材烧蚀有着非常重要的影响,目前很少有弧斑运动相关的研究。研究通过外加脉冲磁场以实现对阴极靶面磁场分布的精确调控,探究了磁场分布对弧斑运动的影响,并结合分形理论分析弧斑的运动轨迹,系统研究了电弧放电过程中靶面电弧弧斑的运动特性。结果表明,在永磁铁磁场与脉冲磁场共同作用下,弧斑在原有的随机运动基础上叠加了反安培力方向的旋转运动与向靶沿扩散的漂移运动。随着靶面总磁场强度的上升,弧斑平均运动速度增加,弧斑寿命变短;弧斑运动范围可控,最大运动范围可覆盖靶面的90%以上;分形维数可控,镍铬合金靶和钛铝合金靶弧斑轨迹图像的最大分形维数可分别为1.145和1.159,对应靶材烧蚀区域面积达到92%。通过改进工艺参数,能够显著减少大颗粒污染并提升膜层质量,同时通过维数可预测靶材烧蚀情况,能更高效地利用靶材。 相似文献
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9.
Ke-fan Chen Jian-hua Deng Fei Zhao Guo-an Cheng Rui-ting Zheng 《Nanoscale research letters》2010,5(9):1449-1455
Carbon nanotubes were subjected to doping with an energetic Ag ion beam, and the carbon nanotubes on the top of the array
were transformed into amorphous carbon nanowires with embedded Ag-nanoparticles. The field emission characteristics of these
nanowires were investigated. The minimum turn-on and threshold fields were 0.68 and 1.09 V/μm, respectively, which were lower
than those of the as-grown carbon nanotubes. This was probably because Ag-nanoparticles embedded in the carbon nanowires reduced
the effective work function from 4.59 to 4.23 eV. Large doping amounts produced serious structural damage at the top of the
nanowires and impaired the field emission characteristics. 相似文献
10.
Real-time bubble behavior characterization and localization are critical in the chemical industry, especially for leakage of sodium-water reactions. This research investigates the properties of bubble signals under different gas injection rates and sodium-water reactions by employing a vibration-based approach. Specifically, the time-frequency and energy characteristics of bubble signals were studied by vibration response. The bubble signals excited by the two kinds of experiments have the same characteristic frequency band of 200–400 Hz, and the maximum energy is obtained at 250 Hz. The bubble signal from the sodium-water reaction can be effectively recognized by identifying the differences in the characteristics of multiple parameters when the gas injection rate is 0.07 m3/h with a signal-to-noise ratio of 11.8–17.1 dB. On the basis of energy analysis of the bubble signal, a bubble signal source location method based on time domain statistics was proposed, and the trajectory curve of the bubble signal excited by the sodium water reaction in the initial 600 ms was successfully obtained with a position error rate less than 5%. Comparative analysis indicates that kurtosis was more sensitive for bubble signal recognition, while the Root Mean Square (RMS) and Standard Deviation (SD) values were more suitable for bubble positioning. Thus, this study complemented the present techniques and knowledge for bubble identification and localization in multiphase flow engineering. 相似文献