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191.
提出一种适合心电信号(ECG)检测的OTA-C滤波器。为了达到低功耗、低截止频率、高直流增益、高阻带衰减、低谐波失真的目的,滤波器采用五阶巴特沃斯全差分低通滤波结构和高增益的两级单端输出OTA,其中OTA电路采用亚阈值区驱动、电流分流和源极负反馈等技术。采用SMIC 0.18-μm 1P6M CMOS工艺进行电路、版图设计及优化。仿真结果表明,滤波器在静态功耗为17.6 μW,截止频率为240 Hz,直流增益为-6 dB,阻带衰减为120 dB每十倍频,三次谐波失真小于-62 dB@ 400 mV,适合应用于心电信号检测模拟前端。 相似文献
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194.
基于多特征相关滤波的红外目标跟踪 总被引:2,自引:2,他引:0
为实现在复杂背景和多干扰条件下红外目标的稳 定跟踪,提出一种基于多特征相关滤波的红外目标 跟踪算法。首先综合考虑生物视觉关注特性及目标运动特性,提取目标区域的空间特征和 运动特征,进而融合一种改进的卷积特征,生成多特征权值函数;然后在传统 相关滤波的基础上,引入多特 征权值函数用以表征不同候选区域的重要程度,形成权值相关滤波的红外目标跟踪框架;最 终得到能够表 征目标位置的置信图,从而完成红外目标的鲁棒跟踪。在6组不同条件下红外视频序列上的 实验结果表明, 和经典目标跟踪算法相比,本文方法在复杂背景下的平均跟踪成功率提升15%左右,能够有 效应对相似虚 假目标、遮挡、背景辐射强度变化和探测器晃动等不良因素的影响,适用于复杂背景条件下 的红外目标跟踪。 相似文献
195.
196.
利用传输矩阵法设计了空气与基本膜系之间具 有3个周期减反膜结构的日盲紫外探测器滤波膜系,并利用半导体 器件仿真软件Atlas分析集成了滤波膜系的GaN/AlGaN异质结雪崩光电探测器(APDs)的光 电性能。研究结果表明,相对 无减反射膜的滤波膜系,本文设计的膜系明显提高了光在日盲区的透过率及截止区的反射率 ,使GaN/AlGaN APDs有更 加平滑的光谱响应曲线、更大的响应度、更陡峭的响应截止边频及更好的滤波性能;同时, GaN/AlGaN APDs比传统AlGaN APDs 更有利于光生空穴的注入,使GaN/AlGaN APDs的最大光谱响应度及紫外/可见抑制比较传统的 APDs提高超过300%。 相似文献
197.
A fundamental concern in the Quantitative Structure-Activity Relationship approach to toxicity evaluation is the generalization of the model over a wide range of compounds. The data driven modelling of toxicity, due to the complex and ill-defined nature of eco-toxicological systems, is an uncertain process. The development of a toxicity predicting model without considering uncertainties may produce a model with a low generalization performance. This study presents a novel approach to toxicity modelling that handles the involved uncertainties using a fuzzy filter, and thus improves the generalization capability of the model. The method is illustrated by considering a data set dealing with the fathead minnow (Pimephales promelas) toxicity of 568 organic compounds. 相似文献
198.
This work demonstrates resolution enhancement of a quadrupole mass filter (QMF) under the influence of a static magnetic field. Generally, QMF resolution can be improved by increasing the number of rf cycles an ion experiences when passing through the mass filter. In order to improve the resolution, the dimensions of the QMF or the operating parameters need to be changed. However, geometric modifications to improve performance increase the manufacturing cost and usually the size of the instrument. By applying a magnetic field, a low‐cost, small footprint instrument with reduced power requirements can be realized. Significant improvement in QMF resolution was observed experimentally for certain magnetic field conditions, and these have been explained in terms of our theoretical model developed at the University of Liverpool. This model is capable of accurate simulation of spectra allowing the user to specify different values of mass spectrometer dimensions and applied input signals. The model predicts enhanced instrument resolution R>26 000 for a CO2 and N2 mixture with a 200‐mm long mass filter operating in stability zone 3 via application of an axial magnetic field. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
199.
Sarata Kumar Sahoo Yuji Nakamura Kunio Shiraishi Akimasa Masuda 《International journal of environmental analytical chemistry》2013,93(12):919-926
A chemical and mass-spectrometric procedure for uranium isotopic analysis using a thermal ionisation mass spectrometer equipped with a Wide Aperture Retardation Potential energy filter has been developed and applied to uranium isotopic measurements for various soil samples. Soil samples were digested using a microwave digestor. Uranium was isolated from soil samples by the chemical separation procedure based on the use of anion-exchange resin and UTEVA extraction chromatography column. The isotope ratios were measured for two certified reference materials by using a VG Sector 54-30 thermal ionisation mass spectrometer in dynamic mode with Faraday cup and Daly ion counting system. Replicates of standard reference materials showed excellent analytical agreement with established values supporting the reliability and accuracy of the method. Precision of the 235U/238U ratio was achieved by a correction factor of 0.22% amu as a function of ion-beam intensity with sample loads of around 250?ng of U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations (SD). Uranium isotopic compositions have been determined in several reference soil samples such as Buffalo river sediment, NIST 2704, river sediment SRM 4350b and ocean sediment NIST-4357 and a Chernobyl soil sample. There was a significant deviation from the natural uranium in comparison with Chernobyl soil samples. 相似文献
200.
Bruce Petrie Ewan J. McAdam Keith H. Richards John N. Lester 《International journal of environmental analytical chemistry》2013,93(13):1343-1355
An ultra-performance liquid chromatography method using a triple quadrupole mass spectrometer was developed and validated for the determination of steroid oestrogens in wastewater matrices. To date, analytical methods established in the literature for 17α-ethinylestradiol have been unable to achieve the proposed predicted no effect concentration of 0.1?ng?l?1. The extensive sample pretreatment and analytical methodology proposed herein enable 17α-ethinylestradiol to be determined at very low background concentrations with a theoretical method detection limit of 0.06?ng?l?1 which has been applied in real environmental matrices. During the validation process, a trickling filter wastewater treatment works was monitored to demonstrate the method's application. Oestrogen removal across the filters demonstrated good removals of natural free oestrogens (≥62.0%) with lower removals of the synthetic oestrogen 17α-ethinylestradiol (29.2%) from wastewaters at 10°C. The method's application illustrates its capability of detecting oestrogen concentrations in real wastewater samples comprising complex organics of comparatively high concentration. Furthermore, a complete process mass balance for 17α-ethinylestradiol is now attainable which has previously posed a challenge owing to the low environmental concentrations typically exhibited, but more significantly as a result of the lower sensitivity inherent in previously reported analytical methods. 相似文献