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排序方式: 共有202条查询结果,搜索用时 15 毫秒
61.
Wei Hongling 《绍兴文理学院学报》2007,(1)
在数字复合正交神经网络(NN)的基础上提出一种模拟复合正交神经网络,并用于轴向磁轴承的控制中.控制器采用模拟复合正交神经网络与PID的并行控制方法,对带有负载干扰的轴向磁轴承控制系统作了PID控制与NN PID控制的仿真实验.仿真结果表明,相对于常规PID控制器,该并行控制法具有非常好的抗干扰与自适应能力,获得了满意的控制效果. 相似文献
62.
退火对软磁合金的最大磁导率影响的机理研究 总被引:6,自引:0,他引:6
曹光明 《潍坊高等专科学校学报》2000,(1)
本文以Fe-Ni软磁合金为研究对象,从晶体缺陷及内应力两方面分析了退火参数对最大磁导率影响的机理,指出位错、晶界以及晶格畸变应力是影响最大磁导率的主要因素。 相似文献
63.
陈蕾 《重庆文理学院学报》2016,35(2):68-71
文章采用超磁致伸缩材料Terfenol-D(Tb0.37Dy0.63Fe2)、金属玻璃Metglas 2605SA1和压电材料PZT(Pb(Zr, Ti)O3),设计了一种基于功能梯度磁电复合材料的新型自偏置磁传感器.利用Metglas和Terfenol-D之间的磁导率和矫顽力差异产生较强的磁化梯度,打破原有的平衡状态,导致内建磁场产生,进一步提高了零偏置磁场下磁致伸缩材料的压磁系数和磁电响应.实验结果表明:该传感器获得了较高的低频和高频零偏置磁电电压系数,分别达到9.14 mV/Oe和572 mV/Oe,并且谐振磁电电压输出和激励交变磁场之间呈线性变化关系.该自偏置磁传感器避免了传统磁电传感器对偏置磁场的依赖,具有制作简单、成本低、体积小,无需偏置磁场以及灵敏度高等优点. 相似文献
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66.
Jörg Polzehl & Vladimir G. Spokoiny 《Journal of the Royal Statistical Society. Series C, Applied statistics》2001,50(4):485-501
We consider the problem of statistical inference for functional and dynamic magnetic resonance imaging (MRI). A new approach is proposed which extends the adaptive weights smoothing procedure of Polzehl and Spokoiny that was originally designed for image denoising. We demonstrate how the adaptive weights smoothing method can be applied to time series of images, which typically occur in functional and dynamic MRI. It is shown how signal detection in functional MRI and the analysis of dynamic MRI can benefit from spatially adaptive smoothing. The performance of the procedure is illustrated by using real and simulated data. 相似文献
67.
Extremely low frequency electric and magnetic fields (ELF EMFs) are a common exposure for modern populations. The prevailing public‐health protection paradigm is that quantitative exposure limits are based on the established acute effects, whereas the possible chronic effects are considered too uncertain for quantitative limits, but might justify precautionary measures. The choice of precautionary measures can be informed by a health‐economics analysis (HEA). We consider four such analyses of precautionary measures that have been conducted at a national or state level in California, the Netherlands, the United Kingdom, and Israel. We describe the context of each analysis, examine how they deal with some of the more significant issues that arise, and present a comparison of the input parameters and assumptions used. The four HEAs are methodologically similar. The most significant qualitative choices that have to be made are what dose‐response relationship to assume, what allowance if any to make for uncertainty, and, for a CBA only, what diseases to consider, and all four analyses made similar choices. These analyses suggest that, on the assumptions made, there are some low‐cost measures, such as rephasing, that can be applied to transmission in some circumstances and that can be justifiable in cost‐benefit terms, but that higher cost measures, such as undergrounding, become unjustifiable. Of the four HEAs, those in the United Kingdom and Israel were influential in determining the country's EMF policy. In California and Netherlands, the HEA may well have informed the debate, but the policy chosen did not stem directly from the HEA. 相似文献
68.
向裕民 《电子科技大学学报(社会科学版)》2000,(3)
为获得二同轴方形载流线圈间相互作用磁力,计算出了线圈间的互感系数。将虚功原理作为一种简捷方法加以运用,对该力极值位置进行了分析和图示。讨论平面内二同心方形线圈载流时一线圈不受磁张力的优良力学状态。 相似文献
69.
The Efficacy of Different Methods for Informing the Public About the Range Dependency of Magnetic Fields from High Voltage Power Lines 总被引:1,自引:0,他引:1
The AC electric and magnetic fields associated with high voltage power lines have become a concern as a possible health risk. In most cases the strength of these fields decreases as the inverse square of the distance from the line. In earlier work, we found that laypeople do not understand how rapidly field strength decreases with distance. Most believe that any high voltage power line they can see is exposing them to strong fields. This paper confirms the earlier finding and explores a number of strategies which might be used in risk communications to correct this misperception. We found it relatively easy to provide subjects with a better understanding of the range-dependency of magnetic field strength. Moreover, the quality of this acquisition was apparently independent of the manner in which they were instructed. Such successful instruction is markedly different from the well-established difficulty of teaching people about many qualitative domains, such as physics or ideas in probability. Clearly, while some erroneous beliefs are highly resistant to change, others can be altered quite readily. We suspect that an important distinction between knowledge about the range-dependency of power-frequency magnetic fields and less tractable topics involves the presence or absence of prior folk-theories or "mental models" of the domain. 相似文献
70.
提出一种新颖的窄线宽半导体激光器测试技术—延迟光纤干涉法。利用部分相干光理论推出延迟光纤干涉的计算公式,通过模拟计算,总结出采用这种技术的测试方法,建立了实验系统,对实验结果进行数据分析,证明了这种新的测试技术方案是正确可行的。 相似文献