全文获取类型
收费全文 | 1305篇 |
免费 | 72篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 20篇 |
综合类 | 32篇 |
化学工业 | 123篇 |
金属工艺 | 9篇 |
机械仪表 | 28篇 |
建筑科学 | 41篇 |
矿业工程 | 5篇 |
能源动力 | 62篇 |
轻工业 | 693篇 |
水利工程 | 23篇 |
石油天然气 | 10篇 |
无线电 | 20篇 |
一般工业技术 | 217篇 |
冶金工业 | 47篇 |
原子能技术 | 4篇 |
自动化技术 | 48篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 29篇 |
2020年 | 29篇 |
2019年 | 29篇 |
2018年 | 37篇 |
2017年 | 32篇 |
2016年 | 24篇 |
2015年 | 41篇 |
2014年 | 47篇 |
2013年 | 69篇 |
2012年 | 52篇 |
2011年 | 109篇 |
2010年 | 67篇 |
2009年 | 67篇 |
2008年 | 68篇 |
2007年 | 80篇 |
2006年 | 98篇 |
2005年 | 83篇 |
2004年 | 78篇 |
2003年 | 68篇 |
2002年 | 68篇 |
2001年 | 35篇 |
2000年 | 39篇 |
1999年 | 24篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1382条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(54):22981-22992
In this study, a three-dimensional model was established using the lattice Boltzmann method (LBM) to study the internal ice melting process of the gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC). The single-point second-order curved boundary condition was adopted. The effects of GDL carbon fiber number, growth slope of the number of carbon fibers and carbon fiber diameter on ice melting were studied. The results were revealed that the temperature in the middle and lower part of the gradient distribution GDL is significantly higher than that of the no-gradient GDL. With the increase of the growth slope of the number of carbon fiber, the temperature and melting rate gradually increase, and the position of the solid-liquid interface gradually decreases. The decrease in the number of carbon fibers has a similar effect as the increase in the growth slope of the number of carbon fibers. In addition, as the diameter of the carbon fiber increases, the position of the solid-liquid interface gradually decreases first and then increases. 相似文献
2.
冰蓄冷系统运行经济性分析 总被引:4,自引:0,他引:4
建筑物的空调制冷系统采用蓄冷方式,可以节约运行费用,减少设备容量,转移用电高峰。蓄冷空调系统与常规空调系统相比,在运行的经济性方面有很多优点。因此开发了冰蓄冷系统运行经济性分析计算机软件,应用这套软件对实际工程项目进行分析,计算出各种冰蓄冷系统与相应常规系统的逐时耗电量、电费、全年运行费用和设备容量减少率等,并以图表的方式对两种系统的经济性作出综合的比较,能全面、直观的显示冰蓄冷系统的优点。 相似文献
3.
N. E. Wijeysundera M. N. A. Hawlader Chan Wee Boon Andy M. Kamal Hossain 《International Journal of Refrigeration》2004,27(5):1997
An ice slurry generation system was developed using direct contact heat transfer between water and the coolant, Fluroinert FC-84. The location of the coolant nozzle is an important design consideration to avoid clogging due to freezing of water. An ice fraction of up to about 40 percent was obtained with the nozzle located at the bottom of the ice slurry tank and the jet directed upwards into the water. Two simplified model were developed to extract the heat transfer coefficient between the coolant drops and the water. The first model requires as input the average drop diameter and the residence time while the second model uses the measured drop diameter distribution. The estimated heat transfer coefficients are much smaller than those computed using single-sphere correlations. 相似文献
4.
River ice jams are a common occurrence on northern rivers, and their formation can present a severe flood risk to nearby communities. As more and more river regulation projects are developed to provide an alternative to fossil fuels for electrical power-generating capacity, our need to understand the mechanisms associated with ice jam formation under variable flow conditions becomes more vital. This is because, at present, hydropeaking operations are often severely curtailed during the ice-affected seasons due to concerns that sudden flow fluctuations might instigate ice jams and associated flooding. Here, an experimental investigation explores the effects of rapid increases in discharge on ice jam formation and evolution. It is found that the thickness of ice jams formed under highly dynamic flow conditions tend to be slightly thinner than those formed during steady carrier flows for comparable discharges. Also, despite the highly dynamic nature of these consolidation events, the resulting ice thicknesses appear reasonably well approximated by steady flow theory. 相似文献
5.
6.
Kazutaka Chibana Chaedong Kang Masashi Okada Koji Matsumoto Tetsuo Kawagoe 《International Journal of Refrigeration》2002,25(2):83
Water-silicone oil emulsion with an additive, (C2H5O)3SiC3H6NH2, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously. 相似文献
7.
Ice recrystallization rates in simple aqueous solutions comprising fructose and a hydrocolloid stabilizer were measured. The stabilizers were an enzyme-modified guar and a non-gelling high methoxy pectin. The stabilizer concentration dependence of the recrystallization rates for both materials was similar in that increasing the concentration resulted in decreasing rates until a point is reached where further addition had no additional effect. That recrystallization rates were reduced by both gelling and non-gelling stabilizers was strongly suggestive that gelation was not a requirement for recrystallization inhibition and another more specific mechanism applies, for example a weak interfacial effect such as adsorption or blocking. This behavior was also seen with locust bean gum and guar and provided further empirical evidence to support the hypothesis that stabilizers adsorb to ice crystal surfaces. 相似文献
8.
采用盐酸处理祛斑霜样品,用还原气化-原子荧光光谱法测定其中的汞,研究了仪器测定条件和不同样品处理方法对测定的影响。结果表明样品处理方法对测定结果影响不大;此方法的加标回收率在96%以上,相对标准偏差为2.5%;此方法具有快速、简便和灵敏的特点。 相似文献
9.