全文获取类型
收费全文 | 343篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 72篇 |
金属工艺 | 3篇 |
机械仪表 | 13篇 |
建筑科学 | 7篇 |
能源动力 | 24篇 |
轻工业 | 21篇 |
水利工程 | 2篇 |
石油天然气 | 9篇 |
无线电 | 39篇 |
一般工业技术 | 53篇 |
冶金工业 | 31篇 |
原子能技术 | 6篇 |
自动化技术 | 79篇 |
出版年
2023年 | 14篇 |
2022年 | 33篇 |
2021年 | 22篇 |
2020年 | 23篇 |
2019年 | 12篇 |
2018年 | 27篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 26篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 14篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有360条查询结果,搜索用时 62 毫秒
31.
This paper introduces a neural network technique for the estimation of global solar radiation. There are 41 radiation data collection stations spread all over the kingdom of Saudi Arabia where the radiation data and sunshine duration information are being collected since 1971. The available data from 31 locations is used for training the neural networks and the data from the other 10 locations is used for testing. The testing data was not used in the modeling to give an indication of the performance of the system in unknown locations. Results indicate the viability of this approach for spatial modeling of solar radiation. 相似文献
32.
The shape and scale parameters of a Weibull density distribution function are calculated for 10 locations in Saudi Arabia. The daily mean wind speed data from 1970 to mid-1990 are used for this purpose. It is found that the numerical values of the shape parameter vary between 1.7 and 2.7, whereas the value of the scale parameter is found to vary between 3 and 6. It is also concluded from this study that wind data are very well represented by the Weibull distribution function. 相似文献
33.
Michael Elkin Yuval Lando Zeev Nutov Michael Segal Hanan Shpungin 《Wireless Networks》2011,17(2):397-410
One of the major concerns in wireless ad-hoc networks design is energy efficiency. Wireless devices are typically equipped
with a limited energy supply sufficient only for a limited amount of time which is reversely proportional to the transmission
power of the device. The network lifetime is defined as the time the first device runs out of its initial energy charge. In
this paper we study the maximum network lifetime problem for broadcast and data gathering in wireless settings. We provide
polynomial time approximation algorithms, with guaranteed performance bounds while considering omnidirectional and unidirectional
transmissions. We also consider an extended variant of the maximum lifetime problem, which simultaneously satisfies additional
constraints, such as bounded hop-diameter and degree of the routing tree, and minimizing the total energy used in a single
transmission. Finally, we evaluate the performance of some of our algorithms through simulations. 相似文献
34.
Magnetization Reversal in CsNiIICrIII(CN)6 Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yoann Prado Sandra Mazerat Eric Rivière Guillaume Rogez Alexandre Gloter Odile Stéphan Laure Catala Talal Mallah 《Advanced functional materials》2014,24(34):5402-5411
CsNiCr(CN)6 coordination nanoparticles with sizes ranging from 6 to 30 nm are highly diluted in an organic polymer matrix. Their static and dynamic magnetic behaviour allows unravelling of surface anisotropy and interparticle dipolar interaction effects. The single magnetic domain critical size is thus evaluated to be around 22 nm with a blocking temperature of 21 K (at ν = 1 Hz) and an effective energy barrier for the reversal of the magnetization of 426 K. 相似文献
35.
Talal Al-Wahaibi Mujeeb Smith Panagiota Angeli 《Journal of Petroleum Science and Engineering》2007,57(3-4):334-346
The effect of a drag-reducing polymer (DRP) in the water phase during horizontal oil–water flow was investigated in a 14 mm ID acrylic pipe. Oil (5.5 mPa s, 828 kg/m3) and a co-polymer (Magnafloc 1011) of polyacrylamide and sodium acrylate were used. Two polymer concentrations were tested, 20 ppm and 50 ppm, made from a 1000 ppm master solution. The results showed a strong effect of DRP on flow patterns. The presence of DRP extended the region of stratified flow and delayed transition to slug flow. The addition of the polymer clearly damped interfacial waves. Annular flow changed in all cases investigated to stratified or dual continuous flow, while slug flow changed in most cases to stratified flow. In the cases where the slug and bubble flow patterns still appeared after the addition of the polymer, the oil slugs and bubbles were seen to flow closer together than in the flow without the polymer. The DRP caused a decrease in pressure gradient and a maximum drag reduction of about 50% was found when the polymer was introduced into annular flow. The height of the interface and the water hold up increased with DRP. There were no large differences on pressure gradient and hold up between the two DRP concentrations. Using a two-fluid model it was found that the addition of the polymer results in a decrease in both the interfacial and the water wall shear stresses. 相似文献
36.
A new algorithm is presented for viewing three-dimensional objects, represented by an octree, from an arbitrary location. The algorithm generates aperspective view of the objects while eliminating hidden surfaces. The viewer can be located anywhere inside or outside the objects. The algorithm presented in this short notefixes an artifact that is generated by a previously published algorithm due to Meagher when the viewer is located in certain regions in space. The new algorithm traverses the octree in a back-to-front order and recursively chooses correct orders for visiting the sons of non-leaf nodes. 相似文献
37.
38.
KH Fye PI Terasaki H Moutsopoulos TE Daniels JP Michalski N Talal 《Canadian Metallurgical Quarterly》1976,19(5):883-886
HLA antigens were examined by microdroplet lymphocyte cytotoxicity in 31 patients with Sj?grens syndrome. Fifty percent of 22 Causcasian patients (7 of 17 females and 4 of 5 males) had HLA-B8, as compared to 21% of 1205 controls (P=0.002). The presence of HLA-B8 was not correlated with parotid salivary flow, keratoconjunctivitis sicca, or focus score. Because of its association with a number of autoimmune diseases, including Sj?gren's syndrome, it is suggested that HLA-B8 is genetically liked to an immune response gene(s) that predisposes the individual to autoimmune phenomena. The expression of autoimmunity may be determined by infectious or environmental factors. 相似文献
39.
40.
Statistical characteristics of wind in Saudi Arabia 总被引:1,自引:0,他引:1