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131.
A thin film of yttrium Y (150 nm) protected by a 6 nm coating of nickel Ni on a glass substrate was completely hydrogenated in a 1 M NaOH electrolyte at a constant negative current until the transparent Y tri-hydride phase was achieved and hydrogen gas evolution from the electrode began. A series of impedance measurements were performed in situ during the electrochemical experiment to study the properties of the system as dependent on hydrogenation degree and time of relaxation. The equivalent electrical circuit (EEC) simulations were performed with a Randles-like scheme R0[R1CPE1], where R0 is the thin film electrode resistance, R1 the charge transfer resistance and CPE1 is the capacitive constant phase element. The behavior of all the components of the EEC undergoes a clear transition when the hydrogenation degree of the electrode is approximated to its maximum value (H to Y ratio 2.7) and electrochemical process changes from hydrogen uptake to hydrogen evolution. 相似文献
132.
Methane was pulsed over pure CuO and NiO as well as Cu/La2O3 and Ni/La2O3 catalysts at 600° C. Results indicate that the mechanisms for methane activation over copper and nickel are quite different. Over CuO, methane is converted to CO2 and H2O, most likely via the combustion mechanism; whereas metallic copper does not activate methane. Over NiO in the presence of metallic nickel sites, methane activation follows the pyrolysis mechanism to give CO, CO2, H2 and H2O. Similar results were obtained over the Cu/La2O3 and Ni/La2O3 catalysts. XRD investigations indicate that copper and nickel existed as CuLa2O4 and LaNiO3 respectively in the La2O3-supported catalysts. The effect of La2O3 on the activation of methane is discussed. 相似文献
133.
以酸性多孔ZSM-5沸石(HZSM-5-M)和高比表面积的氧化硅(SiO2)为载体,采用等体积浸渍法制备了负载Ni2P催化剂(Ni2P/HZSM-5-M和Ni2P/SiO2),对比研究了它们在苯乙炔选择性加氢反应中的催化性能。采用XRD、N2吸附-脱附、NH3-TPD、H2-TPR、SEM和TEM对载体及其负载的Ni2P催化剂进行了表征。催化剂活性结果为:当反应时间为2 h,苯乙炔在Ni2P/HZSM-5-M催化剂的转化率为98.5%,而在Ni2P/SiO2催化剂上仅为45.6%。说明Ni2P/HZSM-5-M催化剂的加氢活性显著高于Ni2P/SiO2催化剂。这是因为,与Ni2P/SiO2催化剂相比,在Ni2P/HZSM-5-M催化剂上形成了小颗粒的Ni2P活性相。同时,Ni2P/HZSM-5-M催化剂的活性具有良好的重复性。 相似文献
134.
135.
The surface chemistry of methoxide (CH3O-) on the Ni(111) surface has been studied in the presence of hydrogen pressures up to 2 Torr. During heating in vacuum methoxide decomposes to H2 and CO, which desorb at 380 and 445 K, respectively. The CH3O-decomposition process is rate limited by CH bond breaking and exhibits a strong deuterium kinetic isotope effect in CD3O-. In the presence of ambient hydrogen pressures of 0.02–2.0 Torr both CH3O- and CD3O-are hydrogenated directly to methanol at 310 K. Methoxide is hydrogenated by adsorbed hydrogen, which nearly saturates the surface at these pressures and temperatures. 相似文献
136.
Hendry L. B. Korzeniowski S. H. Hindenlang D. M. Kosarych Z. Mumma R. O. Jugovich J. 《Journal of chemical ecology》1975,1(3):317-322
The major sex attractant of the oak leaf roller (Archips semiferanus Walker),cis-10-tetradecenyl acetate (I), was synthesized in 55–62% overall yield by a highly economical route from inexpensive azelaic acid (II).Authorized as Paper No. 4779 in the Journal Series of the Pennsylvania Agricultural Experiment Station. 相似文献
137.
Nanocomposite Ni/ZrO2-AN catalyst consisting of comparably sized Ni metal and ZrO2 nanoparticles is studied in comparison with zirconia- and alumina-supported Ni catalysts (Ni/ZrO2-CP and commercial Ni/Al2O3-C) for steam reforming of methane (SRM) and for combined steam and CO2 reforming of methane (CSCRM). The reactions are performed under atmospheric pressure with stoichiometric amounts of H2O and CH4 or (H2O + CO2) and CH4 at 1073 K. Under a wide range of methane space velocity (gas hourly space velocity of methane GHSVCH4 = 12,000–96,000 ml/(h gcat.), the nanocomposite Ni/ZrO2-AN catalyst always shows higher activity and stability for both SRM and CSCRM reactions. The two supported Ni catalysts (Ni/ZrO2-CP and Ni/Al2O3-C) exhibit fairly stable catalysis under low GHSVCH4 but they are easily deactivated under high GHSVCH4 and become completely inactive when they are reacted for ca.100 h at GHSVCH4 = 48,000 ml/(h gcat.). The CSCRM reaction is carried out with different H2O/CO2 ratios in the reaction feed while keeping the molar ratio (H2O + CO2)/CH4 = 1.0, the results prove that the nanocomposite Ni/ZrO2-AN catalyst can be highly promising in enabling a catalytic technology for the production of syngas with flexible H2/CO ratios (ca. H2/CO = 1.0–3.0) to meet the requirements of various downstream chemical syntheses. 相似文献
138.
目前,我国化学工业依然存在自主创新能力不强、产品档次和附加价值低、企业规模小、能源利用率低等问题,并面临环境容量限制和资源短缺的严峻压力。预计“十一五”期间,我国化学工业将继续保持快速发展的态势,但由于全行业面临资源、能源紧张及价格上涨的压力,利润增幅将有所下降。我国必须以科学发展观为指导,调整产业结构,优化产业布局,提高自主创新能力,大力发展循环经济,努力突破一批重大、关键性技术,提高产业技术水平和产品档次,降低能源、资源消耗和污染物排放,才能实现化学工业的可持续、健康发展。 相似文献
139.
S. M. A. M. Bouwens D. C. Koningsberger V. H. J. De Beer S. P. A. Louwers R. Prins 《Catalysis Letters》1990,5(3):273-283
To study the local structure of the Ni promoter atom, the Ni and Mo K edge EXAFS spectra of Ni-MoS2/C hydrodesulfurization catalyst were measured in an in-situ EXAFS cell at 77 K. The Ni atom is situated in a square pyramid of five S atoms at a distance of 2.21 Å from the S atoms. In addition an EXAFS contribution due to a Mo atom at 2.82 Å from the Ni atom could be identified. This local structure indicates that the Ni atoms are situated on top of the S4 squares at the MoS2 edges in millerite-type Ni sites. The Ni atoms are situated in the planes of the Mo atoms and not in the intercalation plane midway between successive MoS2 sandwich layers. 相似文献
140.
采用DUO-ICP-AES同时测定精对苯二甲酸中钴、铬、铁、锰、钼、镍、钛,并对仪器的分析线选择、背景校正、入射功率、雾化器压力、辅助气流量、冷却气流量、蠕动泵转速的影响及共存元素的干扰、硝酸铯灰化助剂等因素进行了详细的研究。方法的检测限:钴0.0097 mg/L;铬0.0021 mg/L;铁0.0078 mg/L;锰0.0012 mg/L;钼0.0027 mg/L;镍0.016 mg/L;钛0.0027 mg/L,回收率和精密度分别为93.0%~99.5%和0.37%~3.2%。该方法快速简便,具有良好的精密度和准确度,适用于进出口精对苯二甲酸的日常检验。 相似文献