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71.
72.
通过低饱和共轭沉淀法制备了不同n(Mg)∶n(Al)的水滑石,并用XRD和BET等技术对催化剂前驱体进行了表征。XRD表征表明,水的加入使得水滑石的结构能够得到部分重建。同时水的加入使水滑石表面的O2- 生成了相应的B碱(OH-),大大提高了催化活性。BET表征结果表明,水滑石作为碱性催化剂的活性位点主要存在于暴露的板层边缘。以制备的水滑石为催化剂在超声辐射下合成了含有强吸电子取代基4,4′-二硝基查尔酮,并考察了超声、催化剂的组成、水合质量和溶剂对催化性能的影响。结果表明,当催化剂的n(Mg)∶n(Al)=3.0、水合质量为其前驱体的35%和溶剂为甲醇时,在超声辐射下具有最高的催化活性,收率达91.3%,选择性为100%。 相似文献
73.
采用化学沉淀法将磁性基质与二维层状水滑石组装制备了磁性的水滑石,再利用浸渍法和滴加吸附的负载方法制备了磁性水滑石负载纳米钯催化剂。通过XRD、ICP—AES、TG、氢气脉冲吸附等分析手段对磁性催化剂晶型结构、形貌及金属分散度进行了表征,考察了用磁性水滑石负载纳米钯催化剂对不同碱、溶剂、溶剂与水比例、时间、温度、催化剂用量等条件对Suzuki反应的影响。实验结果表明,水滑石赋予磁性后结构并没有改变,仍然具有较高的催化活性。反应的最佳条件为:碳酸钾作碱、溶剂为乙醇、与水比例为1:5、反应温度为60℃、反应1h、催化剂用量分别为3.6×10^-3mmol和4.8×10^-3mmol,催化剂重复三次产物收率仍可保持在90%以上。 相似文献
74.
The performance of a novel thermal swing sorption-enhanced reaction (TSSER) concept for simultaneous production of fuel-cell grade hydrogen and compressed carbon dioxide as a by-product from a synthesis gas feed is simulated using Na2O promoted alumina as a CO2 chemisorbent in the process. The process simultaneously carries out the water gas shift (WGS) reaction and removal of CO2 from the reaction zone by chemisorption in a single unit. Periodic regeneration of the chemisorbent is achieved by using the principles of thermal swing adsorption employing super-heated steam purge. 相似文献
75.
Hetero-polyacid anions (PW12O403-)-pillared hydrotalcite-like compound is directly and hydrothermally synthesized by the hot solution method. FTIR and XRD show that PW12O403- has been incorporated into the interstitial space with the dimension of 0.917 nm. The state of PW12O403- anion between the hydrotalcite sheets was also discussed. The title product can be expressed by formula [Zn0.68Al0.32(OH)2]×[PW12O40] 0.11×3H2O after a serious study of TGA and chemical analysis. 相似文献
76.
水滑石/红磷协同阻燃EVA材料的热分解特性 总被引:3,自引:0,他引:3
采用熔融共混方法制备了EVA/水滑石(LDH)/微胶囊化红磷(MRP)无卤阻燃材料,研究了LDH和MRP在乙烯与醋酸乙烯共聚物(EVA)中的阻燃协同作用,发现在EVA/LDH阻燃体系中添加适量的MRP可以显著提高体系阻燃性能,而且燃烧过程中不再有熔滴现象发生。采用TG和实时傅立叶变换红外光谱(RT-FT-IR)研究了EVA及其复合阻燃材料的热分解特性,实验发现,与EVA/LDH体系相比,EVA/LDH//MRP体系的热稳定性有所提高,MRP对EVA/LDH体系中的EVA热氧化降解具有一定的抑制作用。 相似文献
77.
New experimental data are reported to demonstrate that high purity H2 can be directly produced by sorption-enhanced water gas shift (WGS) reaction using synthesis gas (CO + H2O) as sorber-reactor feed gas. An admixture of a commercial WGS catalyst and a proprietary CO2 chemisorbent (K2CO3 promoted hydrotalcite or Na2O promoted alumina) was used in the sorber-reactor for removal of CO2, the WGS reaction by-product, from the reaction zone. The promoted alumina was found to be a superior CO2 chemisorbent for this application because (a) it could directly produce a fuel-cell grade H2 product (<10–20 ppm CO) at reaction temperatures of 200 and 400 °C, and (b) it produced ∼45.6% more high purity H2 product per unit amount of sorbent than the promoted hydrotalcite at 400 °C. Furthermore, the specific fuel-cell grade H2 productivity by the promoted alumina at a reaction temperature of 200 °C was ∼3.6 times larger than that at 400 °C. These striking differences in the performance of the two CO2 chemisorbents were caused by the differences in their CO2 sorption equilibria and kinetics. 相似文献
78.
《Drug development and industrial pharmacy》2013,39(6):728-734
Objective: The aim of this study was to prepare pH-sensitive sodium alginate/calcined hydrotalcite (SA/CHT) hybrid bead with improved the burst release effect of the drug.Materials and methods: A series of pH-sensitive SA/CHT hybrid beads were prepared by using Ca2+ cross-linking in the presence of diclofenac sodium (DS) and SA. The structure and drug loading of the beads were characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The swelling and the drug release of the fabricated beads were investigated by the pH of test medium and CHT content.Result: The formed positively charged hydrotalcite layers were adsorbed on the negatively charged SA polymer chains through electrostatic interaction and act as inorganic cross-linkers in the three-dimensional network. Compared to pure SA beads, the incorporation of CHT enhanced the drug encapsulation efficiency, improved the swelling behaviors and slowed the drug release from the hybrid beads.Discussion and conclusions: The electrostatic interaction between hydrotalcite and SA has restricted the movability of the SA polymer chains, and then slowed down swelling and dissolution rates in aqueous solutions. The results provided a simple method to moderate drug release and matrix degradation of the SA beads. 相似文献
79.
目的 介绍海藻酸钠基抗菌复合材料的抗菌机理、特点以及在食品包装方面的应用。方法 重点阐述海藻酸钠的成膜机理、纳米氧化锌的抗菌机理,以及具有特殊层状结构的无机功能材料水滑石的抑菌性能,利用在不同改性方法下水滑石与氧化锌结合形成的增强抗菌结构,探究以海藻酸钠为基材制成的海藻酸钠/水滑石/纳米氧化锌复合膜体系的力学、阻隔和抗菌等性能。结论 绿色食品包装材料在现实生活中倍受关注,将海藻酸钠(能完全生物降解,具有良好的生物相容性和热稳定性的环境友好型材料)与水滑石-氧化锌抗菌剂结合,以增强抗菌复合材料的综合性能,符合国内外研究和开发新型抗菌材料的趋势。 相似文献
80.