全文获取类型
收费全文 | 692篇 |
免费 | 82篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 36篇 |
综合类 | 54篇 |
化学工业 | 119篇 |
金属工艺 | 43篇 |
机械仪表 | 47篇 |
建筑科学 | 85篇 |
矿业工程 | 19篇 |
能源动力 | 7篇 |
轻工业 | 97篇 |
水利工程 | 13篇 |
石油天然气 | 38篇 |
武器工业 | 6篇 |
无线电 | 81篇 |
一般工业技术 | 86篇 |
冶金工业 | 13篇 |
原子能技术 | 2篇 |
自动化技术 | 63篇 |
出版年
2024年 | 8篇 |
2023年 | 36篇 |
2022年 | 46篇 |
2021年 | 69篇 |
2020年 | 50篇 |
2019年 | 41篇 |
2018年 | 24篇 |
2017年 | 33篇 |
2016年 | 13篇 |
2015年 | 35篇 |
2014年 | 39篇 |
2013年 | 35篇 |
2012年 | 41篇 |
2011年 | 41篇 |
2010年 | 43篇 |
2009年 | 28篇 |
2008年 | 30篇 |
2007年 | 36篇 |
2006年 | 35篇 |
2005年 | 23篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 5篇 |
排序方式: 共有809条查询结果,搜索用时 92 毫秒
71.
Kiyonobu Kasama Yujing Jiang Akihiko Hiro-Oka Noriyuki Yasufuku Hidefumi Sato 《Soils and Foundations》2011,51(4):575-589
Torrential rainfall in mid-July 2009 triggered numerous geodisasters such as slope failure and debris flow in Chugoku and Northern Kyushu areas of Japan. A number of slope failures and debris flows occurred in Yamaguchi and Fukuoka prefectures resulting in extensive damage to human life and infrastructure. One of the most serious geodisasters included a slope failure followed by debris flow at Sasaguri-machi and Fukuchi-machi, Fukuoka prefecture, Japan. This paper summarizes the results of geotechnical investigations on the geodisaster sites in Fukuoka prefecture. The geotechnical investigation included determining a series of grain size distributions, consistency limits and conducting direct box shear tests for collapsed soils collected at six disaster sites. The generation mechanisms of slope failure followed by debris flow were also investigated by analyzing the precipitation, topography, geology, and strength properties of the collapsed soils. Moreover, slope deformation and stability analyses were coupled with an unsaturated-saturated seepage analysis to investigate the slope failure mechanism. The main findings from the study are summarized as: The physical properties, such as the grain size distribution, the plastic limit and liquid limit of collapsed soils, are summarized and compared with the results of other failure slopes in the literature. The collapsed soil was characterized as being a well grained soil (the uniformity coefficient >50) and highly weathered (the ignition loss >5%), however, with regard to the liquid limit and plastic index, there were no remarkable findings. The original shear strength for collapsed soils with natural water content is relatively large and slope failure doesn't occur because the cohesion in the shear strength is induced by a suction force between the soil particles under unsaturated condition. However, water seepage into the soil induces a drastic decrease in the shear strength, which is mainly caused by a decrease in cohesion (losing suction) resulting from soil saturation. In addition, the drained/undrained condition in the shear process is also sensitive to shear strength. For example, both water seepage and the shear process with constant volume cause an approximate 30% reduction in shear strength for Fukuchi-machi and Sasaguri-machi soil samples. Therefore, the reduction of cohesive strength due to water seepage and the low permeability of the slope are the parameters which trigger geodisaster. Based on the results of slope deformation and a stability analyses which took the change in water pressure and cohesive strength into account, the geodisaster at Fukuchi-machi was simulated, it is reasonable to assume that the shallow failure near the top of slope occurred due to torrential precipitation of about 100 mm per hour which triggered a debris flow. 相似文献
72.
Polystyrene (PS) foam materials are lightweight, but suffer from poor compressive strength and heat resistance, among other problems, which limit their application. Herein, a method for preparing PS foam with high compressive strength and high heat resistance using supercritical CO2 is proposed. PS/polyphenylene oxide (PPO) blends were prepared using a corotating intermeshing twin-screw extruder. The results showed that PPO exhibited excellent molecular-level compatibility with PS, which substantially improved mechanical properties and heat resistance of PS. Foam samples of PS/PPO blends with the same expansion ratio were prepared via batch foaming experiments, and the compressive strength of different foams was determined at different temperatures. At room temperature, the compressive strength of the PS/PPO-30% foam increased by 173% compared with pure PS foam. As the testing temperature increased from 30 to 120°C, the compressive strength of pure PS foams decreased rapidly. Nevertheless, PS/PPO foams maintained high compressive strength at high temperatures. 相似文献
73.
74.
75.
76.
77.
以钒钼法对发酵液中植酸酶活性进行了测定,并对影响酶活性测定结果的因素进行了研究.实验结果表明,钒钒法测磷的灵敏度和线性范围分别为0.025mmol/L和0.025mmol/L~0.6mmol/L;为减小植酸酶活性的测定误差,结果测定必须在颜色反应结束后的4h以内完成.研究中同时发现,发酵液含有的无机磷远远大于酶活测定产生的无机磷含量,直接用发酵液测得的植酸酶酶活是不可靠的.通过对透析2h的发酵液进行植酸酶酶活的测定,实验结果的最大相对偏差仅为7.1%. 相似文献
78.
太阳能半导体空调制冷装置模块化实验研究 总被引:1,自引:0,他引:1
建立了以水为热交换媒介的太阳能热电模块制冷实验系统.系统配置了双位能量存储装置,用以储存昼夜温差能和太阳光电转换电能,以备无日照或日照不足时系统能够连续工作.热电制冷装置模块化,用以适应制冷功率变化较大的空间制冷,并在制冷启动与温度维持不同阶段实现较大功率的切入或撤出.制冷模块以半导体热电元件为核心,冷热端均以导热性能良好的紫铜作为热交换材料,以热容量较大的水作为冷却液和散热循环液.热交换装置采取集合散热冷却分流的集散一体化热交换系统.对制冷模块制冷性能进行了实验分析,并对制冷效果进行了模拟实验,实验结果基本达到了设计的预期. 相似文献
79.
基于单片机的恒温水龙头设计 总被引:1,自引:1,他引:0
介绍了基于单片机的恒温水龙头的设计方法.针对传统冷热双联式水龙头手动调节水温,不能实现出水温度的精确控制等缺点,将单片机作为智能控制器应用于水龙头中.利用单片机检测DS18820采集到的水温,经过分析计算可控制冷热水入水比例,通过循环水系统将混水过程中未达温度的水重新注入加热装置的入水口,实现重复利用.该系统实现了双联式水龙头的精确调温,保证恒温用水的同时实现了高效节水,适用于各种恒温用水的场合,具有较高的应用价值. 相似文献
80.