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排序方式: 共有222条查询结果,搜索用时 31 毫秒
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目前,国际最高光辐射功率基准为低温辐射计,其可探测光谱范围覆盖真空紫外到太赫兹波段(115 nm~T Hz),利用真空低温超导条件下的电替代测量原理,将光辐射功率参数溯源到可以精确测量的电参数进行高精度测量,实现超宽光谱范围的光辐射绝对功率测量,其测量不确定度达到10-5量级,尤其在国防军事和光辐射计量领域,光电有效载... 相似文献
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针对低温微量超声雾化声学系统中的关键部件单波长超声雾化喷嘴进行研究。首先基于等效电路原理和传输矩阵法分别建立了带中心孔换能器和带中心孔复合变幅杆的频率方程,并应用数学分析软件获得了准确的数值解,实现了超声雾化喷嘴的全谐振。然后,对其进行有限元动力学分析和振动特性测试,结果表明二者相对于设计频率25 kHz的偏差率在0.6%以内,且空载超声振幅达13.5μm。之后,应用流体仿真分析软件对砂轮-工件磨削区进行流场特性分析,结果表明低温微量超声雾化声学系统可以解决磨削区涡流现象的产生。最后,通过对该系统使用前后两种润滑方式的磨削结果进行测试发现:低温微量超声雾化润滑不仅切削液使用量少,而且可以避免工件表面出现烧伤和硬度降低。 相似文献
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A. L. Woodcraft R. V. Sudiwala M. J. Griffin E. Wakui B. Maffei C. E. Tucker C. V. Haynes F. Gannaway P. A. R. Ade J. J. Bock A. D. Turner S. Sethuraman J. W. Beeman 《International Journal of Infrared and Millimeter Waves》2002,23(4):575-595
We describe techniques for testing and characterising semiconductor bolometers, using the bolometer model presented in Sudiwala et. al. [1]. The procedures are illustrated with results from a prototype bolometer for the high frequency instrument (HFI) in the Planck Surveyor cosmic microwave background mission. This is a bolometer using spider-web geometry and a neutron transmutation doped (NTD) germanium thermistor, designed for operation at 100 mK. Details are given of the laboratory facility used to take data at temperatures from 70 mK to 350 mK. This employs an adiabatic demagnetisation refrigerator to cool the detector and optics. The spatial and spectral properties of the optical system are controlled using feedhorns and edge filters. To characterise the bolometer, blanked and optically loaded load curves were measured over a range of temperatures, and the response to modulated radiation was measured as a function of modulation frequency, temperature and bias current. Results for the prototype bolometer show that its behaviour is well represented by an ideal thermal detector down to a temperature of approximately 100 mK. Below this, non-thermal effects such as electron-phonon decoupling or electric field dependent resistance appear to lead to departure from ideal behaviour. The performance was in good agreement with the design goals for the bolometer. 相似文献
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本文采用低温气相色谱法分析了火焰气体的成份和深度,色谱柱固定相为PoraparkQ,柱温范围-99-250℃氦气作载气。在所选择的实验条件下,火焰气体中的N2和O2有效地得到分离,可迅速精确地分析确定N2的浓度以及其他成份和浓度。 相似文献
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G. J. Stacey J. W. Beeman E. E. Haller N. Geis A. Poglitsch M. Rumitz 《International Journal of Infrared and Millimeter Waves》1992,13(11):1689-1707
We have constructed and used two dimensional arrays of both unstressed and stressed Ge:Ga photoconductive detectors for far-infrared astronomy from the Kuiper Airborne Observatory (KAO). The 25 element (5×5) arrays are designed for a new cryogenically cooled spectrometer, the MPE/UCB Far-Infrared Imaging Fabry-Perot Interferometer (FIFI). All of the pixels for the stressed array performed well on the first flights with FIFI; 25% of the detectors in the array are more sensitive than our best single element detector, with background limited noise equivalent powers (NEPs)3.0×10–15 W Hz–1/2 at 158 m and 40 km s–1 spectral resolution. The average array element performs within±15% of this value. With a bias field of 0.1 V/cm, the average detector response is 20±6 Amp/Watt at 158 m. The cutoff wavelength and response also compare well with our single element detectors. The unstressed array delivers significantly better performance than our single element detector due to the lower thermal background in the new spectrometer. The average background limited NEp at 88 m and 35 km s–1 spectral resolution is 7×10–15 W Hz–1/2. The least sensitive pixel is only 40% less sensitive. The unstressed array response at 88 m with a bias field of 1 V/cm is 5±1 Amp/Watt. Twenty four of the 25 elements worked on the first flights-on subsequent flights all channels have worked. Some of the exciting new science possible with far-infrared detector arrays is also discussed. 相似文献