全文获取类型
收费全文 | 111篇 |
免费 | 9篇 |
国内免费 | 52篇 |
专业分类
电工技术 | 10篇 |
综合类 | 10篇 |
化学工业 | 9篇 |
金属工艺 | 3篇 |
建筑科学 | 61篇 |
能源动力 | 2篇 |
轻工业 | 2篇 |
水利工程 | 2篇 |
无线电 | 41篇 |
一般工业技术 | 8篇 |
冶金工业 | 6篇 |
原子能技术 | 4篇 |
自动化技术 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 296 毫秒
1.
本文介绍的电路可同时进行时间和电荷校准,它的校准量程大,精度高,稳定性好,可输出864路指数形校准信号,并可手动或程控。它的时间校准精度优于±250ps,电荷量校准精度优于±1%。 相似文献
2.
本文初步研制了一种测定游离胆固醇的酶传感器。该传感器用于流动注射法的最佳工作条件:磷酸盐缓冲液作载液(pH=6.3,0.1mol/L),流动速度为0.5mL/min,温度为27℃,检测限为0.15mg/mL~1.14mg/mL,线性响应范围0.25~1.00mg/mL,斜率0.08μA·mL/mg,响应时间为0.5~2.0min,工作寿命15d。已将该传感器用于样品分析,取得初步满意的结果。 相似文献
3.
4.
研制了一种新的PVC膜铬(Ⅵ)电极,其电活性为季铵盐与氯铬酸根缔合物。实验过四种不同的季铵盐,发现三庚基十二烷基碘化铵[(C_7H_(15))_3C_(12)H_(25)Nl]效果最佳。该电极在5×10~(-6)~1×10~(-1)mol·L~(-1)范围,有接近Nernst的响应,斜率为58mv/10倍程,其检测下限为3×10~(-6)mol·L~(-1)。将此电极用于实际样品(鞣革废水及铬鞣液)中铬的测定,所得到的结果与比色法吻合。还试验过该电积的响应电位与试液酸度间的关系,并发现与计算机模型的计算结果很相符。 相似文献
5.
A. Abdul-Latif J.Ph. Dingli K. Saanouni 《Mechanics of materials : an international journal》1998,30(4):287-305
Based on the crystallographic slip theory, a micromechanical model for polycrystal elasto–inelasticity is proposed and applied to describe the mechanical behavior of a such structure under monotonic and cyclic loading paths. Small strain theory and isotropic elasticity are assumed. Biaxial cyclic loading is of particular interest in proposed work. The kinematic hardening of the polycrystal is naturally obtained from the averaging scheme. In this scheme, we use a self-consistent interaction law. The proposed modeling effort is tested for a FCC metal under different loading situations in order to elucidate its capability. The obtained results show that this model reproduces appropriately the principle cyclic features such as Bauschinger effect, strain memory effect, ratcheting and additional hardening and other effects. 相似文献
6.
基于CORDIC算法的数字鉴频方法及其在FPGA中的实现 总被引:2,自引:0,他引:2
本文给出了一种适合FPGA实现的基于CORDIC(Coordinate Rotation Digital Computer)算法的数字鉴频方法.首先讨论了利用CORDIC算法进行数字鉴相和一阶差分数字鉴频的原理,然后分别给出在FPGA中实现CORDIC算法的流水结构和迭代结构,通过与XILINX自带CORDIC IPCore资源利用情况的比较及FPGA仿真结果表明,基于CORDIC算法的迭代结构和一阶差分实现数字鉴频的方法是高效可行的. 相似文献
7.
Qian Fang Dingli Zhang Louis Ngai Yuen Wong 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2011,26(6):750-763
Ground surface settlement induced by urban subway construction using shallow tunnelling method is inevitable and it may cause a series of negative impact to existing nearby structures and utilities. In order to guarantee environmental safety, a risk management methodology which aims at process control for ground settlement and existing nearby structures is proposed. It includes 5-stage technology-based steps: survey of existing conditions, designing control standards for key risk factors, analyzing environmental response under tunnel construction and designing process control standards, monitoring and taking proper process control measures during construction, and risk reassessment after construction. This methodology was put into practice in the Huangzhuang subway station construction which is the largest cross interchange subway station construction using shallow tunnelling method in China. According to site survey, nearby pipelines and existing buildings were determined to be the key risk factors. The risk control standards for nearby pipelines and existing buildings were made according to available standards in China and related literatures. Design of process control standards for ground surface settlement was assisted by numerical simulation, which aimed at controlling the key risk factors. During construction, monitoring was adopted for the nearby pipelines, existing buildings and ground surface. After the four drifts excavation of the double-deck part of Line 4, a series of risk control measures, which included treatment of the unfavorable geological bodies, installation of roof pipes, compensation grouting, full-face grouting and some other control measures, were taken. Due to these risk control measures, ground surface settlements, except at two measuring points of Line 4, were successfully controlled under the given process control standards for both Line 4 and Line 10. All the pipelines and buildings were under their normal service state during tunnel construction. The maximum deflection for the 6 pipelines above the station was controlled to be within 2 mm/m and the maximum settlement of all the monitoring points for the pipelines was less than 30 mm. For the four important existing buildings in close vicinity, the maximum deflection was less than 1 mm/m; the maximum settlement value was 6.8 mm and the maximum uplift value was 3.0 mm. The risk control system was shown to be effective in ensuring environment safety, structure safety and construction safety. These safety control methods, the methodology of designing these control standards and the measures taken in the construction can serve as a practical reference for other similar projects. 相似文献
8.
9.
隧道拱顶塌方事故是近年来隧道施工中造成重大人员伤亡的主要事故类型,危害极大,因此必须掌握隧道拱顶塌方发生机理和演化规律、制定科学有效的控制对策,为塌方事故的防治提供依据。基于上限变分法,建立深埋地层中隧道拱顶塌方模型,研究隧道拱顶塌方范围及其影响因素,进一步建立软弱破碎围岩隧道拱顶渐进性塌方模型,推导渐进性塌方范围全过程曲线,并与模型试验结果进行对比。据此提出了拱顶塌方事故的安全性控制措施,揭示预控制、过程控制两类措施下拱顶塌方安全性控制机理和承载特性,提出支护措施的围岩荷载确定方法。结果表明:隧道塌方宽度L随着初始粘聚力c0和单轴抗拉强度σt的增大而增大,随着重度γ和非线性系数m的增大而减小;隧道塌方高度h1随着抗拉强度σt和非线性系数m的增大而增大,随着初始粘聚力c0和围岩重度γ的增大而减小;基于渐进性塌方过程中围岩物理力学参数逐渐减弱的特性,建立了考虑围岩粘聚力和抗拉强度衰减的隧道拱顶渐进性塌方模型;根据控制机理和目标,将拱顶塌方控制措施分为预控制措施和过程控制措施;围岩的形变荷载和总荷载随着塌方荷载的增大而增大。相关研究成果将为隧道拱顶塌方的预测及安全性控制提供借鉴。 相似文献
10.
利用相位模板,在248nm KrF准分子激光器光束的照射下,在国产高掺锗单模光纤中制作出了中波长为1547nm,峰值反射率约为10%,带宽为0.64nm的调制光纤由拉格光栅。 相似文献