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121.
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Precise aerosol information is indispensable in providing accurate clear sky irradiance forecasts, which is a very important aspect in solar facility management as well as in solar and conventional power load prediction. In order to demonstrate the need of detailed aerosol information, direct irradiance derived from Aerosol Robotic Network (AERONET) ground based measurements of aerosol optical depth (AOD) was compared in a case study over Europe to irradiance calculated using a standard aerosol scenario. The analysis shows an underestimation of measurement-derived direct irradiance by the scenario-derived direct irradiance for locations in Northern Europe and an overestimation for the Mediterranean region.Forecasted AOD of the European Dispersion and Deposition Model (EURAD) system was validated against ground based AERONET clear sky AOD measurements for the same test period of February 15th to 22nd, 2004. For the time period analyzed, the modelled AOD forecasts of the EURAD system slightly underestimate ground based AERONET measurements. To quantify the effects of varying AOD forecast quality in their impact on the application in solar energy industry, measured and forecasted AOD were used to calculate and compare direct, diffuse, and global irradiance. All other influencing variables (mainly clouds and water vapour) are assumed to be modelled and measured correctly for this analysis which is dedicated to the specific error introduced by aerosol forecasting. The underestimated AOD results in a mean overestimation of direct irradiance of +28 W/m2 (+12%), whereas diffuse irradiance is generally underestimated (−19 W/m2 or −14%). Mean global irradiance values where direct and diffuse irradiance errors compensate each other are very well represented (on average +9 W/m2 or +2%). 相似文献
123.
The design philosophy, construction and measured performances of a plane-reflector augmented box-type solar-energy cooker are presented. The experimental solar cooker consists of an aluminum plate absorber painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator. The reflector consists of a wooden-framed commercially available specular plane mirror which is sized to form a cover for the box when not in use. Provision is made for four cooking vessels, each capable of holding upto 1 kg of water. Results of thermal performance tests show stagnation absorber plate temperatures of 138°C and 119°C for the cooker with and without the plane reflector in place respectively. Boiling times of 60 min (3600 s) and 70 min (4200 s) for 1 kg of water, for the cooker with and without the plane reflector in place, respectively, were recorded. The solar cooker performance has been rated using the first figure of merit (F1) on the no-load test and the second figure of merit (F2) on the sensible heat tests. Predicted water boiling times using the two figures of merit compared favourably with measured values. The performance of the cooker with the plane reflector in place was improved tremendously compared to that without the reflector in place. 相似文献
124.
透明蜂窝结构太阳辐射透过率的简化分析 总被引:3,自引:2,他引:3
对透明蜂窝结构太阳辐射透过率进行理论分析,提出一个适用于工程应用的近似公式,该方法忽略了对透过率贡献极小的透明蜂窝材料的散射,漫反射和漫透射,认为进入蜂窝单元底部的太阳辐射由三部分组成:1)经壁面的多次透射,2)经本单元壁面多次反射,3)经相邻单元的多次透射与反射,其中第一部分是主要的,据此,可导出横截面为四边形的蜂窝结构的透过率随太阳辐射入射角变化的近似公式,并由实验结果得到验证。 相似文献
125.
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127.
高低频混合方法估算角反射器阵RCS 总被引:1,自引:0,他引:1
结合高频算法处理复杂目标雷达散射截面(RCS)的思路,提出了利用HFSS仿真软件得到的数据计算复杂目标RCS,给出了计算式,并运用Matlab验证计算公式的适用性。 相似文献
128.
一种面向LED扩展光源的道路配光设计 总被引:3,自引:3,他引:0
在多车道的道路照明中,需要非对称矩形配光。本文根据非成像光学理论,建立点光源空间与目标照明面之间的拓扑关系,采用合适的反馈优化方法,获得面向扩展光源且在路面上形成均匀非对称矩形光斑的反射器,仿真结果表明,配光后光源的能量基本上被限制在20m×12m的矩形区域内,且实现了非对称的配光,横向照度均匀度达到了85%,纵向照度均匀度达到了80%,满足道路照明要求;并且通过开模实际测试出整体的照度均匀度为80.13%,验证仿真结果以及证明了设计方案的可行性和反射器在路灯灯具中的实用性。 相似文献
129.
This study proposes a solution for optimizing the distance between a solar module and reflector for an indoor energy harvesting system. It is a process in which energy(ambient light) is captured and converted directly into electricity. Inside a building, this energy could be used to supply power to wide range of portable equipment or offset other electrical energy usage and associated costs. The proposed reflector element was designed and tested in a real indoor environment to confirm its effectiveness. A distance-optimization method for the placement of a polycrystalline photovoltaic (PV) module and a mirror was described, and the performance characteristics of the system were investigated qualitatively through visual observation and quantitatively through measuring voltage and ampere values. The solar PV system with a reflector element displayed a 10% increase in voltage when compared with that without. As the distance between PV module and the reflector increased, the voltage and ampere reading decreased, thus the distance was optimized to gain maximum readings. Various studies employing reflectors have also showed increases in voltage readings with different designs, suggesting that reflectors are economically viable optical elements that can boost the voltage output of a PV module. In practice, the distance-optimized PV module can be placed in buildings with extended indoor lighting duration away from disrupting building activity. 相似文献
130.
重反射层的应用可提高反应堆中子经济性,其结构和中子吸收特性均与压水堆常规围板/反射层差异较大,因此对核设计程序的计算分析能力提出了新的要求。为分析重反射层建模方案对堆芯中子学计算结果的影响,使用先进中子学程序SCAP N和确定论堆芯高保真模拟程序NECP X对压水堆重反射层问题进行了高保真模拟,分析了5种反射层建模方案下计算结果的差异,并将高精度计算结果与商用核设计程序系统进行了对比。数值结果表明,重反射层水洞内冷却剂温度变化对计算结果影响较小;相较精确建模方案,重反射层铁水打混建模方案造成的反应性计算偏差在±30 pcm以内、组件相对功率分布计算偏差在±2%以内。 相似文献