全文获取类型
收费全文 | 155篇 |
免费 | 1篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 40篇 |
综合类 | 7篇 |
化学工业 | 21篇 |
金属工艺 | 26篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
矿业工程 | 5篇 |
能源动力 | 1篇 |
轻工业 | 4篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
武器工业 | 5篇 |
无线电 | 3篇 |
一般工业技术 | 42篇 |
冶金工业 | 6篇 |
原子能技术 | 2篇 |
出版年
2022年 | 1篇 |
2018年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 30篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有177条查询结果,搜索用时 15 毫秒
1.
天荒坪抽水蓄能电站输水系统设计 总被引:1,自引:0,他引:1
天荒坪工程上游输水系统为斜井,一洞三机,输水道总长与平均发电水头的比值为2.5。6台机组有两个相同的水力单元,中心距为59.54m,承受680m的最大静水头,输水系统全长1435m。尾水部分长245.3~253.8m,为单机单洞,共6条尾水洞。岔管采用钢筋混凝土结构,平底两次分岔,分岔角度为60°。高压钢管承受最大内压为8.7MPa,近厂房段钢管按明管设计,离厂房边线18m外按埋管设计并考虑钢管、衬砌和围岩三者联合作用。为保证钢衬回填质量,高压钢管均不设加劲环,在回填混凝土和回填浆液中掺适量微膨胀剂,并采用设置排水廊道和钢管外排水等措施降低外水压力。经充水试验观察,高压钢管部位缝隙值小于设计值,外水压力接近零,效果较好。 相似文献
2.
Preparation and electrochemical performance of nanosized Co3O4 via hydrothermal method 总被引:1,自引:0,他引:1
The hydrotalcite-type cobalt compounds were prepared through oxidation of Co(OH)2 gel using NH4OH as precipitating agent and H2O2 as oxidant. These hydrotalcite-type cobalt compounds were transformed into Co3O4 through hydrothermal decomposition with nanostructural deformation. The precursor and product were characterized by Fourier-transform infrared(FT-IR) spectrum, X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The electrochemical performances of as-prepared nanosized Co3O4 as anode materials in lithium-ion batteries were tested by charge-discharge test in the voltage range of 0-3.0 V. The influence of morphology of Co3O4 particle on the capacity and cycling performance was studied. The results show that the shape and size of the final product can be controlled by altering cobalt sources. The irregular cubic Co3O4 with the average particle size of about 10 nm shows the best electrochemical performance. After 10 charge-discharge cycles, the specific charge capacity retains 555 mA.h/g. 相似文献
3.
4.
Citrate-stabilized CdSe/CdS quantum dots as fluorescence probe for protein determination 总被引:1,自引:1,他引:0
A rapid, ultrasensitive and convenient fluorescence measurement technology based on the enhancement of the fluorescence intensity
resulting from the interaction of functionalized CdSe/CdS quantum dots (QDs) with bovine serum albumin (BSA) was proposed.
The citrate-stabilized CdSe/CdS (QDs) were synthesized by using Se powder and Na2S as precursors instead of any pyrophoric organometallic precursors. The modified CdSe/CdS QDs are brighter and more stable
against photobleaching in comparison with organic fluorophores. At pH 7.0, the fluorescence signal of CdSe/CdS is enhanced
by increasing the concentration of BSA in the range of 0.1–10 μg/mL, and the low detection limit is 0.06 μg/mL. A linear relationship
between the enhanced fluorescence peak intensity (ΔF) and BSA concentration (c) is established using equation ΔF=50.7c+16.4 (R=0.996 36). Results of determination for BSA in three synthetic samples are identical with the true values, and the recovery
(98.9%–102.4%) and relative standard deviation (RSD, 1.8%–2.5%) are satisfactory. 相似文献
5.
Characteristics of graphite felt electrode electrochemically oxidized for vanadium redox battery application 总被引:2,自引:0,他引:2
The graphite felt was oxidized at a positive electrode potential in sulfuric acid solution.The electrochemical performance of the treated graphite felt served as electrode for vanadium redox battery was investigated with FT-IR,SEM,XPS,BET,cyclic voltammetry and testing VRB system,respectively.The results show that the molar ratio of O to C increases from 0.085 to 0.15 due to the increase of—COOH functional groups during electrochemical oxidation treatment,and the GF surface is eroded by electrochemical oxidation,resulting in the surface area increase from 0.33 m2/g to 0.49 m 2/g.The VRB with modified GF electrode exhibits excellent performance under a current density of 30 mA/cm 2 .The average current efficiency reaches 94%and average voltage efficiency reaches 85%.The improvement of electrochemical activity for the electrode is ascribed to the increase of the number of—COOH group and the special surface of GF. 相似文献
6.
不同锰源合成尖晶石型LixMn2O4及其性能 总被引:1,自引:2,他引:1
以自制γ—MnO2(SPDM)和电解二氧化锰(EDM)为原料,采用流变相法合成了尖晶石型锂锰氧材料。应用XRD,SEM,TG和DSC等手段研究了原材料性质和配比等因素对合成尖晶石型锂锰氧的结构、粒径、比表面积以及充、放电性能的影响。结果表明,采用流变相法在700-760℃下,反应12h即可得到均相、无杂质、锰平均氧化价态接近3.5的LixMn2O4正极材料;以SPDM为锰源较EMD为锰源在相同条件下合成的尖晶石材料的首次充、放电容量更高,比表面积更大,粒度更小;当原材料中n(Li)/n(Mn)在一定范围内变化时,合成的锂锰氧的晶格常数随材料中锂与锰摩尔比的增大而减小。 相似文献
7.
8.
9.
10.
全钒液流电池用碳毡电极的改性研究 总被引:2,自引:1,他引:2
分别采用普鲁士蓝(Prussianblue,PB)和草酸对聚丙稀腈基(PAN)碳毡进行修饰处理,通过循环伏安法研究了修饰后材料在钒溶液中的电化学性能。结果表明PB修饰碳毡电极对V(Ⅳ)/V(Ⅴ)电对具有良好的电催化性能,V(Ⅱ)/V(Ⅲ)电对在草酸修饰碳毡电极上的活性相比处理前也有较大改善。分别以这两种修饰电极为正负极组装全钒氧化还原液流电池(VRB),通过电池性能测试获得了最适宜的修饰条件。使用修饰电极的静态钒电池在电流密度为35mA·cm-2时电压效率可达83.28%。 相似文献