全文获取类型
收费全文 | 299篇 |
免费 | 3篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 1篇 |
综合类 | 22篇 |
化学工业 | 89篇 |
金属工艺 | 5篇 |
机械仪表 | 2篇 |
建筑科学 | 28篇 |
矿业工程 | 10篇 |
能源动力 | 21篇 |
轻工业 | 7篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 33篇 |
一般工业技术 | 39篇 |
冶金工业 | 17篇 |
原子能技术 | 19篇 |
自动化技术 | 8篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 28篇 |
2010年 | 19篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有306条查询结果,搜索用时 281 毫秒
1.
Metin Kul Muhsin Zor Ahmet Senol Aybek Sinan Irmak Evren Turan 《Solar Energy Materials & Solar Cells》2007,91(10):882-887
The CdO:F samples have been deposited onto microscope glass substrates at 250 °C by ultrasonic spray pyrolysis method. With the incorporation of fluorine into CdO, the direct optical transition has shifted towards the shorter wavelengths, and the transparency of the material has increased at a given wavelength above the fundamental absorption edge. The shift in the absorption edge is explained by means of the Moss–Burstein effect, which is also supported with the results of the current–voltage characteristics. Here, a correlation has been established between the band broadening and the increase in conductivity due to the increase in carrier density. 相似文献
2.
采用微波高压制样技术,快速提取饲料中的氟元素,结合氟离子选择性电极标准添加和电位极差测试方法,能够快速、准确地测试饲料中的含氟量 相似文献
3.
Jung Joon Lee Heeyeon Kim Jae Hyun Koh Ara Jo Sang Heup Moon 《Applied catalysis. B, Environmental》2005,61(3-4):274-280
The performance of a new type of CoMoS/Al2O3 catalyst, with added fluorine and prepared by sonochemical and chemical vapor deposition (CVD) methods, was investigated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The catalyst, which was designed to contain optimum amounts of fluorine and cobalt, exhibited a higher activity, ca. 4.6 times higher activity particularly in the HDS of 4,6-DMDBT, than a fluorine-free catalyst prepared by a conventional impregnation method. The enhanced activity of the new catalyst can be attributed to the cumulative effects of individual factors involved in the catalyst preparation. That is, the use of a sonochemical synthesis led to a high dispersion of small MoS2 crystallites on the alumina, and the addition of the Co species to the catalyst by CVD caused a close interaction between the Co species and the MoS2 crystallites to produce numerous CoMoS species, which are the catalytically active species for HDS. The addition of fluorine increased the amounts of acidic sites in the catalyst, which promoted hydrogenation (HYD) route to a greater extent than the direct desulfurization (DDS) route in DBT HDS and both HYD and DDS routes to similar extents in the case of 4,6-DMDBT HDS. Accordingly, the addition of fluorine led to a greater increase in catalytic activity for 4,6-DMDBT HDS than for DBT HDS. 相似文献
4.
Fate of the chlorine and fluorine in a sub-bituminous coal during pyrolysis and gasification 总被引:1,自引:0,他引:1
The fate of the chlorine and fluorine present in a sub-bituminous coal from Indonesia during pyrolysis and gasification has been studied with fixed and entrained bed reactors. The rate profile for HCl evolved in the temperature programmed pyrolysis exhibits the main and shoulder peaks at 480 and 600 °C, respectively. Model experiments and subsequent Cl 2p XPS measurements show that HCl reacts with metal impurities and carbon active sites at 500 °C to be retained as inorganic and organic chlorine forms, from which HCl evolves again at elevated temperatures. It is suggested that the HCl observed in the coal pyrolysis may originate from the above-mentioned chlorine functionalities formed by secondary reactions involving the nascent char. In the CO2 gasification of the 900 °C char at 1000 °C and 2.5 MPa, any measurable amounts of HCl and HF could not be detected even at a high conversion of 75 wt% (daf), suggesting the accumulation of these halogens in the residual char. When the coal is injected into an O2-blown, entrained bed gasifier at 1200-1400 °C under 2.6 MPa, the partial oxidation proceeds to a larger extent at a higher O2/coal ratio, whereas the chlorine and fluorine are enriched in the remaining char, and the extent of the enrichment at the latter stage of gasification is larger with the fluorine. The XPS measurements of the chars reveal the presence of the broad F 1 s peak, which can cover a wide range of binding energies attributable to inorganic and organic fluorine. The halogen enrichment during gasification is discussed in terms of secondary reactions of HCl and HF with char. 相似文献
5.
核壳型含氟丙烯酸酯共聚乳液 总被引:3,自引:0,他引:3
以十二烷基硫酸钠(SDS)和壬基酚聚氧乙烯基醚(OP-10)为复合乳化剂,甲基丙烯酸十二氟庚酯(Actyflon-God)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为原料制备了壳层含氟的核壳型丙烯酸酯共聚物乳液。用红外光谱(FT—IR)表征乳胶膜化学组成,用透射电子显微镜(TEM)观察了乳胶粒的微观形态结构,并用X射线光电子能谱(XPS)进行了表面分析。发现氟有向空气与膜面迁徙的现象。通过吸水率表征含氟丙烯酸酯共聚物乳胶膜的表面性能,结果表明含氟量增加使乳胶膜吸水率大大降低。 相似文献
6.
Fluorine-graphite intercalation compounds have been synthesized using high purity fluorine gas and high oxidation-state transition-metal fluorides, AgF3 and NiF3, at room temperature and at −78 °C. At room temperature, a mixture of stage 1 + 2 − 4 compounds with compositions, C4.2F to C14.6F were obtained. On the other hand, stage 2–4 compounds with compositions C5.6F to C14.2F were synthesized at −78 °C. The fluorinating ability of AgF3 and NiF3 has been shown more clearly at room temperature because a small amount of fluorine was intercalated/absorbed into graphite at −78 °C without catalysts. XPS spectra show that ionic, nearly ionic, semi-covalent and covalent fluorines coexist in the CxF samples, and that the covalency of CF bonding increases with decreasing stage number. 相似文献
7.
建立菊蓝抗流感片中蒙花苷的含量测定方法。采用高效液相色谱法,DiamonsilTMC18柱(250m×4.6m,5μm),流动相为甲醇-水-冰醋酸(43∶57∶1),检测波长为326nm。蒙花苷在0.251 2~2.512μg的范围内具有良好的线性关系,r=0.999 8;平均回收率为98.9%(RSD为0.3%)。可为菊蓝抗流感片的质量控制提供依据。 相似文献
8.
陈国华 《军民两用技术与产品》2015,(6)
介绍了传统无氟发泡工艺具体工况,分析了聚氨酯泡沫存在容易产生形变、强度和韧性不高和工艺中附加物分散性不佳等问题,本文提出一种改进的无氟发泡工艺,与传统的无氟发泡工艺相比,改进的无氟发泡工艺能有效解决聚氨酯泡沫易形变的问题,提高了聚氨酯的强度及韧性,增加了附加物的分散性效果,降低了发泡体系设备.对进一步改善无氟发泡工艺技术具有重要意义. 相似文献
9.
改善火炕炕面温度分布技术模拟 总被引:5,自引:0,他引:5
为了使火炕的表面温度分布均匀,提高室内环境的热舒适性,提出了倾斜布置炕板来改善炕面温度分布的不均匀性.通过对炕板倾斜程度不同的落地炕和吊炕进行数值模拟,结果表明:当落地炕的炕头粘土层厚度为80 mm、炕梢粘土厚度为20 mm时具有相对最佳的取暖效果;当吊炕的炕头粘土层厚度为80 mm、炕梢粘土厚度为20 mm时具有相对最佳的取暖效果. 相似文献
10.
火炕采暖在我国北方农村地区非常普遍,为了取得更好的采暖效果,在原有火炕的基础上,以我国北方农村地区火炕中的回风洞(俗称“狗洞”)为研究对象,通过三组实验对烟囱进口处高温烟气的温度和速度进行了测定,依据流体运动中的三大守恒定律,分别建立了三组实验中烟囱内高温烟气流动的平面二维数学模型,利用FLUENT软件对烟囱内烟气的流动状态进行数值模拟,分析了烟囱进口烟气的运动趋势以及回风洞的有无对反风时火炕采暖系统的影响,最后得出结论是回风洞能有效地减弱外界风流的反向作用,阻止了突然自然反风而造成的烟气回流,甚至是火苗外窜的安全隐患。 相似文献