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排序方式: 共有592条查询结果,搜索用时 18 毫秒
1.
Li[Ni0.65Co0.13Mn0.22]O2 cathode with two‐sloped full concentration gradient (TSFCG), maximizing the Ni content in the inner part of the particle and the Mn content near the particle surface, is synthesized via a specially designed batch‐type reactor. The cathode delivers a discharge capacity of 200 mAh g?1 (4.3 V cutoff) with excellent capacity retention of 88% after 1500 cycles in a full‐cell configuration. Overall electrochemical performance of the TSFCG cathode is benchmarked against conventional cathode (CC) with same composition and commercially available Li[Ni0.8Co0.15Al0.05]O2 (NCA). The TSFCG cathode exhibits the best cycling stability, rate capability, and thermal stability of the three electrodes. Transmission electron microscopy analysis of the cycled TSFCG, CC, and NCA cathodes shows that the TSFCG electrode maintains both its mechanical and structural integrity whereas the NCA electrode nearly pulverizes due to the strain during cycling.  相似文献   
2.
《Ceramics International》2020,46(9):13331-13341
In this study, zirconia (ZrO2) and dysprosia-stabilized zirconia (DySZ) nanocrystals were synthesized using a chemical coprecipitation method. The crystal structure and micromorphology of the as-synthesized powders, as well as the structural evolution from precursors to oxides were investigated, and the synthesis mechanism was also examined. Results show that pure ZrO2 powders mainly comprise the monoclinic ZrO2 phase with trace tetragonal ZrO2, while the DySZ powders exhibit a tetragonal ZrO2 structure. In addition, the crystal growth rate of DySZ is far slower than that of the pure ZrO2 under elevated calcination temperature. The addition of Dy could significantly improve the phase stability of DySZ powder and effectively inhibit the crystal growth of DySZ. In the DySZ precursor, the binding energy of chemical bonds is significantly difference than in the ZrO2 precursor. A composite hydroxide can be formed with -Zr-OH-Dy- and -Zr-OH-Zr- units in the tetramer structure because of the in-situ substitution of Zr by Dy atoms. Both the ZrO2 and DySZ precursors exhibit analogous dehydration and crystallization behaviours in calcination process. Dy-doping plays a significant role in stabilizing both the intermediate product and the DySZ crystal.  相似文献   
3.
The 0.05 at.% Co:MgAl2O4 precursor was synthesized by the coprecipitation method from a mixed solution of magnesium, aluminum, and cobalt nitrates using ammonium carbonate as the precipitant. 0.05 at.% Co:MgAl2O4 transparent ceramics were successfully obtained via vacuum sintering and hot isostatic pressing (HIP) of 0.05 at.% Co:MgAl2O4 nanopowder calcined at 1100°C for 4 hours. The properties of powder and ceramics were comprehensively investigated. X-ray diffraction (XRD) results showed that Co:MgAl2O4 nanopowder had a pure spinel phase. Also, the in-line transmittances of the HIP posttreated Co:MgAl2O4 ceramics with the thickness of 1.2 mm were 82% at 400 nm and 84.7% at 900 nm. The average grain sizes of 0.05 at.% Co:MgAl2O4 ceramics before and after the HIP posttreatment were 11 and 28 μm, respectively. The calculated ground state absorption cross section of 0.05 at.% Co:MgAl2O4 ceramics was 2.9 × 10−19 cm2, indicating that this ceramics is a promising material applied as a saturable absorber for passive laser Q-switches in the 1.3-1.7 μm domain.  相似文献   
4.
5.
采用共沉淀法制备LaMgAlO(简称Me_xO_y)复合金属氧化物,以Me-xO_y为载体,采用浸渍法制备系列负载型RuO_2/Me_xO_y催化剂,应用BET、TEM、XRF和SEM对代表性样品进行表征。结果表明,实验条件下,RuO_2负载质量分数2.0%时比较合适,在气体混合物中含有氧和少量水蒸汽条件下,催化剂具有较好的催化分解N_2O稳定性。  相似文献   
6.
We herein report a novel carbon-coated coprecipitation method to synthesize non-agglomerating submicron/nano-β-Yb2Si2O7 powders. Yb(C2H3O2)3·4H2O and silica sol (alkaline) were chosen as the ytterbium source and silicon source, respectively. A carbon surface layer is processed using sucrose as carbon source to hinder the contact and sintering of β-Yb2Si2O7 particles during heat treatment under a protective atmosphere, and then the carbon layer could be completely removed by inletting air at 900°C during cooling process. The as-synthesized Yb2Si2O7 powders demonstrate an average size of 271 nm with a narrow distribution of 142–531 nm. The results show that the carbon layer could successfully solve the severe agglomeration or sintering of nanometer β-Yb2Si2O7 particles during the calcination process. The as-developed carbon-coated coprecipitation technique is an effective method to fabricate high purity submicron/nano-Yb2Si2O7 powders.  相似文献   
7.
The nickel‐iron hydroxide‐like catalyst for oxygen evolution reaction (OER) is prepared by an improved coprecipitation method. The crystallization degree of hydrotalcite‐like compound is high, and the lamellar structure is homogeneous with no agglomeration, which helps to build efficient mass‐transfer layer channel of OH? ions. The NiFe layered double hydroxide (LDH)/carbon nanotubes (CNTs) electrode shows good performance and stability for OER. The potential of NiFe LDH/CNTs electrode is only 0.592 V (vs HgO/Hg) at 200 mA·cm?2 in 6 mol·L?1 potassium hydroxide (KOH) electrolyte, which shows excellent catalytic activity for OER. The NiFe LDH/CNTs electrode works continuously for 620 hours at 200 mA·cm?2, with the groove voltage only rises 0.1 V.  相似文献   
8.
Prussian blue analogues are considered as the promising cathodes for sodium-ion batteries. Since the electrochemical properties are closely related to the morphology, the monodisperse copper hexacyanoferrate nanoflakes with highly crystalline are synthesized by a glycol-assisted coprecipitation method and a tentative synthetic mechanism is proposed to explain the formation of nanostructures. The structure and electrochemical properties are characterized by X-ray photoelectron spectroscopy, FTIR spectra and galvanostatic cycle tests, respectively. Due to the novel architecture of copper hexacyanoferrate, a high electrochemical activity is obtained, resulting a high initial coulombic efficiency of 93%, a capacity retention of 73% at 1?C after 300 cycles and 51?mAh?g?1 is maintained at high rate of 15?C at 25?°C.  相似文献   
9.
湿法混炼共沉胶新材料的制备与研究   总被引:1,自引:0,他引:1  
首先采用硅烷偶联剂Si69对白炭黑进行表面改性,改善其不易分散性,然后将白炭黑做成水分散体添加到天然胶乳或合成胶乳中,再进行共沉和烘干,制得共沉橡胶新材料。经实验,白炭黑改性时间100min,温度65℃;改性白炭黑用量范围在30phr~50phr,混合时间为30min时,制得共沉胶性能最佳。  相似文献   
10.
利用尿素的高温分解制备锰和镍的碳酸盐前驱体,然后通过高温固相法制备富锂Li1.2Mn0.6Ni0.2O2正极材料。采用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、能量散射光谱(EDS)、电化学交流阻抗频谱(EIS)和充放电测试对样品的物理及电化学性能进行表征和测试。研究结果表明,700℃下制备的样品结晶度较高,形貌规整,表现出良好的电化学性能,20 m A/g充放电电流条件下,首次放电比容量为184.07 m Ah/g。  相似文献   
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