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References: 《金刚石与磨料磨具工程》2004,(3):52-56
Well-dispersed nanodiamond(ND) aqueous suspensions in both acidic and alkaline environments is prepared by mechanochemical treatment. All the ND particles in the suspensions are smaller than 100nm in dimension with a narrow size distribution, and no destabilization phenomena were detected in a duration of more than one year. Stable. dispersion of ND in the media may attributed to the strong electrostatic repulsion between particles because of the adsorption of dispersants, while mechanical forces may strengthen this adsorption reaction. Good adaptability and applicability of the suspensions to the change of ND concentration and surrounding temperature are observed, and improved performances of ND diamonds are obtained when used in uhrafine polishing and composite plating. 相似文献
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采用磁悬浮熔炼-水冷铜模吸铸法制备出Ti40Ni40Cu20非晶基复合材料板状试样,通过压力试验机对试样进行不同程度的预压缩,然后在150℃、30min下退火,研究了预变形退火工艺对合金微观组织和力学性能的影响。结果表明:奥氏体相在外力作用下发生马氏体相变,形变诱导相变加之退火释放残余热应力从而对非晶基体起到增强增韧的作用。随着预变形程度的增加,马氏体相和奥氏体相均增加,而马氏体相增加的更快,复合材料的屈服强度提高,塑性减小, 塑形阶段预变形能够实现屈服强度可控; 相似文献
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采用铜模负压吸铸工艺制备了(Zr0.6336Cu0.1452Ni0.1012Al0.12)100-xTmx(x=0~5,原子分数)块体金属玻璃(BMG)合金,研究了Tm对合金力学性能和抗腐蚀性能的影响。结果表明,当Tm含量增加到3%时,其玻璃形成能力(GFA)和压缩塑性显著提高,但过量Tm会降低GFA。x=3时合金的最大过冷液相区宽度为100 K,抗压强度为1669 MPa,塑性应变为21.01%,远高于Zr0.6336Cu0.1452Ni0.1012Al0.12 BMG的各项性能(67 K、1439 MPa和5.90%)。然而,电化学测试结果表明,x=3时的合金在3.5%(质量分数)NaCl溶液中的耐腐蚀性不佳,且其耐腐蚀性和力学性能随Tm含量的变化趋势与预期不同。可能是由于过量添加稀土元素Tm,容易形成更多的氧化物,导致点蚀加剧。进一步添加Tm可以提高Zr基BMG钝化膜的完整性和耐点蚀性能,但力学性能不理想。 相似文献
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g‐C3N4 Loading Black Phosphorus Quantum Dot for Efficient and Stable Photocatalytic H2 Generation under Visible Light
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Lingqiao Kong Yujin Ji Zhenzhen Dang Junqing Yan Ping Li Youyong Li Shengzhong Liu 《Advanced functional materials》2018,28(22)
Black phosphorus (BP) is an interesting two‐dimensional material with low‐cost and abundant metal‐free properties and is used as one cocatalyst for photocatalytic H2 production. However, the BP quantum dot (BPQD) is not studied. Herein, for the first time, BPQD is introduced as a hole‐migration cocatalyst of layered g‐C3N4 for visible‐light‐driven photocatalytic hydrogen generation. A high‐vacuum stirring method is developed for BPQD loading without the dissociation of BP. The layered BPQD is coupled on the layered g‐C3N4 surface to form a heterojunction structure. The 7% BPQD–C3N4 samples show similar time‐resolved photoluminescence curves as 0.5% Pt–C3N4. The optimum hydrogen rates of the modified sample (7% BPQD–C3N4) are 190, 133, 90, and 10.4 µmol h?1 under simulated sunlight, LED‐405, LED‐420, and LED‐550 nm irradiation, respectively, which are 3.5, 3.6, and 3 times larger than that of the pristine g‐C3N4. Such low‐cost layered system not only optimizes the optical, electrical, and texture properties of the hybrid materials for photocatalytic water splitting to generate hydrogen but also provides ideas for designing novel or easily oxidized candidates by incorporating different available materials with given carriers. 相似文献
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描述了核燃料非破坏性分析技术的概况及核技术在这个领域内的典型应用和进展,如核燃料和核废物中铀、钚含量的快速测定等。所采用的方法如无源γ射线法、X射线法、无源中子计数法及有源中子质询法等。介绍了这些方法的原理、特点和主要用途。 相似文献
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Guangbao Wu Xing Li Jiyu Zhou Jianqi Zhang Xuning Zhang Xuanye Leng Peijun Wang Ming Chen Dongyang Zhang Kui Zhao Shengzhong Liu Huiqiong Zhou Yuan Zhang 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Layered Ruddlesden–Popper (RP) phase (2D) halide perovskites have attracted tremendous attention due to the wide tunability on their optoelectronic properties and excellent robustness in photovoltaic devices. However, charge extraction/transport and ultimate power conversion efficiency (PCE) in 2D perovskite solar cells (PSCs) are still limited by the non‐eliminable quantum well effect. Here, a slow post‐annealing (SPA) process is proposed for BA2MA3Pb4I13 (n = 4) 2D PSCs by which a champion PCE of 17.26% is achieved with simultaneously enhanced open‐circuit voltage, short‐circuit current, and fill factor. Investigation with optical spectroscopy coupled with structural analyses indicates that enhanced crystal orientation and favorable alignment on the multiple perovskite phases (from the 2D phase near bottom to quasi‐3D phase near top regions) is obtained with SPA treatment, which promotes carrier transport/extraction and suppresses Shockley–Read–Hall charge recombination in the solar cell. As far as it is known, the reported PCE is so far the highest efficiency in RP phase 2D PSCs based on butylamine (BA) spacers (n = 4). The SPA‐processed devices exhibit a satisfactory stability with <4.5% degradation after 2000 h under N2 environment without encapsulation. The demonstrated process strategy offers a promising route to push forward the performance in 2D PSCs toward realistic photovoltaic applications. 相似文献
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赵盛忠 《中国水能及电气化》2015,(5)
碾压混凝土坝在施工过程中大多工期较长,浇筑强度要求较高。因此,需要跨越高温季节难关,实现全年连续性施工。本文结合西盟南康河二级水电站工程实际经验,围绕高温地区碾压混凝土坝施工技术及其优化中的关键温度展开了系统分析与研究,希望能够为同类型工程施工作业提供参考与帮助。 相似文献