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61.
Daylon Black Ryan Harper Patrick Ward Jacob Davlin Omar Bentancourt Donald Plumlee Jim Browning 《International Journal of Applied Ceramic Technology》2020,17(5):2393-2406
A low temperature co-fired ceramic (LTCC) material system has been used to develop a protype field emission cathode structure for use in an experimental magnetron oscillator. The structure is designed for used with 30 gated field emission array (GFEA) die electrically connected through silver metal traces and electrical vias. To approximate a cylinder, the cathode structure (48 mm long and 13.7 mm in diameter) is comprised of 10 faceted plates which cover the GFEA dies. Slits in the facet plates allow electron injection. The GFEA die (3 mm × 8 mm) are placed in axial columns of 3 and spaced azimuthally around a cylindrical support structure in a staggered configuration resulting in 10 azimuthal locations. LTCC manufacturing techniques were developed in order to fabricate the newly designed cathode with seven layers wrapped to form the cylinder with electrical traces and vias. Two different cathode wrapping techniques and two different via filling techniques were studied and compared. Two different facet plate manufacturing techniques were studied. Finally, four different support stand configurations for firing the cylindrical structure were also compared with a square post stand having the best circularity and linearity measurements of the fired structure. 相似文献
62.
《Journal of the European Ceramic Society》2020,40(8):3270-3278
Ultra-stable CsPbBr3 perovskite quantum dots (QDs) multicomponent glass with high transmittance was prepared by melt-quenching heat treatment. The average diameter of the CsPbBr3 QDs was ∼1.96 nm. The resulting glass displayed a high exciton binding energy of 362 ± 18 meV. Notably, these glass-encapsulated materials exhibited excellent resistance to heat, light, and water, superior to that of previously reported perovskite-based materials, and underwent an extremely low rate of Pb leaching during water immersion. Based on the glass, a high-performance white light-emitting diode (WLED) device was fabricated with Commission Internationale de L’Eclairage (CIE) coordinates of (0.3156, 0.3326) and color gamut of ∼113 % National Television Standards Committee (NTSC). The CsPbBr3 QDs glass without rare earth elements further acted as an optical gain medium, realizing up-conversion lasing with 980-nm laser excitation for the first time. The reversible linear fluorescence response indicates that the glass could be a potential candidate for temperature sensors. 相似文献
63.
An extensive evaluation of low-cost dust sensors was performed using an exponentially decaying particle concentration. A total of 264 sensors including 27 sensors with light-emitting diodes (LEDs) and 237 sensors with laser lighting sources were tested. Those tested sensors were classified into 4 groups based on the deviation from the reference data obtained by a reference instrument. The response linearities of all the tested samples for PM1, PM2.5, and PM10 were in excellent agreement with the reference instrument, except a few samples. For the measurements of PM1 and PM2.5, the lighting source, that is, LED or laser, did not show any significant difference in overall sensor performance. However, LED-based sensors did not perform well for PM10 measurements. The 32, 24, and 16% of all the tested sensors for PM1, PM2.5, and PM10 measurement, respectively, are in the category of Class 1 (reference instrument reading ± 20%) requirement. The performance of the low-cost dust sensors for PM10 measurement was relatively less satisfactory. 相似文献
64.
《能源学会志》2020,93(2):642-648
The change of mineral composition in ash and the effect of CaO on the melting characteristics of coal ash were studied by adding different contents of CaO to coal ash. At the same time, the Factsage thermodynamics software was used to simulate the mineral changes in the synthetic ash to support and verify the experimental results. The results show that with the increase of CaO content, the melting characteristic temperature of coal ash first decreases and then rises. After adding a certain amount of CaO, the quartz with higher melting point completely disappears, and the melting point of the coal ash reaches a minimum value. And with the increase of CaO content, the appearance of wollastonite and single crystal calcium oxide mineral makes the melting point of coal ash gradually increase. It can be seen from the phase diagram calculated by Factsage that as the CaO content increases, the corresponding position of the coal ash gradually moves from the hematite region to the calcareous region. And the phenomenon of low temperature eutectic occurs when the CaO content is 35%, which is consistent with the trend of temperature change of the melting characteristics. These phenomena all indicate that the change in the melting point of coal ash is nonlinear as the content of CaO minerals increases. 相似文献
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66.
选择Sasobit和Evotherm 3G两种温拌剂对温拌LDPE沥青混合料制备工艺和性能进行研究。首先,比较变温等体积法和等黏温度法两种方法,并确定两种温拌混合料的拌和及击实温度。在此基础上,分别采用车辙试验、低温弯曲试验、中点加载弯曲试验以及冻融劈裂试验评价70#、LDPE、Sasobit-LDPE以及3G-LDPE四种沥青混合料的高温性能、低温性能、疲劳性能和水稳定性。结果表明,两种温拌技术均是可行的,Sasobit和3G温拌技术可使施工温度降低20℃和15℃。与热拌LDPE沥青混合料相比,Sasobit温拌沥青混合料具有更好的高温性能和水稳定性,在高应力比条件下抗疲劳性能更好,低温性能虽变差,但是优于70#沥青混合料;3G温拌沥青混合料的高温性能,低温性能以及水稳定性则与热拌LDPE沥青混合料各项性能较为接近,抗疲劳性能变差,但是优于70#沥青混合料。 相似文献
67.
摘要:针对水下无线传感网络中运动节点定位精度低的问题,提出了一种新的基于双层修正无迹卡尔曼的水下节点定位算法(DLMUKF)。该算法利用下层无迹卡尔曼滤波算法对节点状态进行预测,根据各信标节点的测距传播时延对预测的节点状态进行修正。运用上层无迹卡尔曼滤波算法对修正后的状态进行新的预测与修正。仿真实验中,DLMUKF算法的平均定位误差约为传统多边定位算法的15%,约为基于无迹卡尔曼滤波(UKF)定位算法的16%,受节点运动时间与速度的影响最小。通过实验证明DLMUKF算法能更充分利用实际距离值,可以有效减小运动节点的定位误差。 .txt 相似文献
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70.
Sarabjeet Singh Sidhu Malkeet Singh Preetkanwal Singh Bains 《Particulate Science and Technology》2018,36(3):324-331
The present study investigates the thermal conductivity of bimodal SiC particulate distribution in aluminum matrix composites fabricated via powder metallurgy route. The effects of the SiCp reinforcement size distribution and processing parameters such as sintering time and temperature on the thermal conductivity have been examined. The Box–Behnken experimental array was employed to identify the effects of selected variables on the thermal conductivity of the composite. A reasonable augmentation in the thermal conductivity was observed with an increase in sintering time and %volume fraction of fine SiC particulates. It has been demonstrated that the matrix doped with fine SiC particulates (37?µm) occupied interstitial positions and formed continuous SiC–matrix network resulting in minimizing the micropores that contributed for good thermal conductivity, that is, 235?W/mK. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were conducted to evaluate the microstructure architecture and interfacial phase formation. 相似文献