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81.
The effect of alumina pretreatment on the performance of alumina supported nickel catalysts was demonstrated in gas phase hydrogenation of toluene to methylcyclohexane. The state of the alumina was changed from pure to pure phase through various heat treatments in air. The catalysts were prepared from vapor phase by saturating the accessible binding sites on the pretreated alumina with the nickel precursor. The highest number of active sites for hydrogenation was observed for catalysts prepared on alumina having an incomplete phase transition and a / alumina phase ratio between 0.5 and 10. Results from temperature programmed desorption (TPD) studies revealed that a maximum in weakly chemisorbed hydrogen as well as in total amount of desorbed hydrogen was found for the same catalysts. By hydrogen chemisorption studies the total hydrogen uptake was found to correlate with the observed hydrogenation maximum. It is suggested that both the chemical and physical properties of the alumina influence the activity. An optimal metal-support interaction and structural defects on the alumina due to the phase transition can explain the observed maximum in the number of active sites and in hydrogen uptake. 相似文献
82.
Jairton Dupont Paulo A.Z. Suarez Alexandre P. Umpierre Roberto F. de Souza 《Catalysis Letters》2001,73(2-4):211-213
The combination of 1-n-butyl-3-methylimidazolium chloride with ZnCl2 affords ionic mixtures with different melting point temperatures depending on the zinc molar fraction. RuCl2(PPh3)3 immobilised in the low melting mixture (60°C) promotes the 1-hexene hydrogenation (turnover frequencies up to 44 min–1) and the recovered solid catalyst phase can be reused several times. 相似文献
83.
综述了国内外苯胺加氢制环己胺与二环己胺催化剂的进展,按活性组分分别对钴系,钌系,镍系,钯系苯胺加氢催化剂研究现状进行叙述,并提出了今后的研究方向。 相似文献
84.
85.
The configurational sequences of 1,2-unit in a series of hydrogenated syndiotactic 1,2-polybutadienes were determined in relation to the sequence distribution of 1,2- and 1,4-units on the basis of the 13C-n.m.r. signal assignment of the methyl carbons. The observed triad distributions of 1,2- and 1,4-units and configurational distributions of the 1,2-unit are in good agreement with the calculated distributions from transition probabilities. The number average sequence lengths of the 1,2-unit and the 1,2-unit in the racemic addition are 5.7 to 8.0 and 4.1 to 5.4, respectively. From the extrapolation of the plot of the number average sequence length against the crystallinity of the starting 1,2-polybutadienes, the minimum sequence length for crystallization is estimated to be 3.7 for the 1,2-unit in the racemic addition. 相似文献
86.
磁性催化剂的研究进展 总被引:1,自引:0,他引:1
磁性催化剂具有磁响应特征,可利用外磁场将其分离和回收,其应用克服了传统催化剂在分离与回收过程中能耗高、质量损失大等问题,降低了反应成本。因此,对磁性催化剂的研究具有现实意义。重点阐述了磁性催化剂的合成及其在氧化反应、加氢反应、偶合反应等领域的应用研究进展,并对磁性催化剂的发展趋势进行了展望。 相似文献
87.
采用CuO-ZnO/Al2O3纳米铜基催化剂催化4-异丁基苯乙酮(IBAP)加氢制备1-(4-异丁基苯基)乙醇(IBPE);然后以PdCl2/PPh3/CuCl2为催化体系,将IBPE经羰基化反应合成2-(4-异丁基苯基)丙酸(布洛芬)。研究结果表明:在反应温度80℃,氢气压力1.5MPa,n(H2)∶n(IBAP)=40∶1,液空速0.30h-1的条件下,IBAP的加氢转化率为100%,IBPE收率达到93.6%。以盐酸为酸性介质、丁酮为溶剂,在温度100℃,CO压力5.5 MPa,反应时间24h的条件下,IBPE羰基化合成布洛芬,IBPE的转化率为100%,布洛芬收率达到72.9%。 相似文献
88.
Xiao Fan Baitang Jin Shoujie Ren Shiguang Li Miao Yu Xinhua Liang 《American Institute of Chemical Engineers》2021,67(11):e17353
The roles of interaction between two catalyst components in CuO–ZnO–ZrO2–Al2O3 (CZZA)/HZSM-5 bifunctional catalyst for dimethyl ether (DME) synthesis via carbon dioxide hydrogenation were investigated. It was found that CZZA catalyst showed excellent stability during methanol (MeOH) synthesis for 100 h, while there was a severe loss of catalytic activity in the bifunctional catalyst for DME synthesis. Hence, the effects of different degrees of intimacy of two catalyst components were studied for DME synthesis, including mixed and separated modes. For the mixed mode, the particle size of catalysts and the amount of reaction intermediates were proven to influence the catalyst deactivation. For the separated mode, the catalysts showed rapid deactivation within a short time. Various characterizations indicated that the remarkable deactivation of separated mode was mainly caused by the decrease of copper active centers (e.g., sintering and oxidation) and blockage of acid sites via increased coke deposition on HZSM-5. 相似文献
89.
采用计算流体力学(CFD)软件FLUENT,以用户自定义函数(UDF)添加化学反应和反应热,对实验室带有陶瓷膜管分散器的催化柴油管式液相加氢脱硫反应器进行模拟计算,得出反应床层不同部位的硫化物含量分布和温度分布状况。从反应床层的入口到出口,催化柴油的硫化物含量逐渐下降,且下降速度趋缓。在压力6.5 MPa、混氢量0.84%(m)、空速2 h~(-1)、进口温度633 K的条件下,位于床层高度0.15 m处出现最高温度点643.8 K,径向温差最大2.1 K,表明催化柴油管式液相加氢脱硫反应器催化剂装填合适的高径比为4~6。工艺条件的模拟结果表明:随着进口温度上升、混氢量增加、空速减小脱硫率提高,与实验数据吻合程度较好,说明模拟研究过程中采用的模型和控制方程准确性较高。 相似文献
90.
The Fe/AlPO4-5 catalysts are prepared by impregnation with aqueous and organic solution (acetic acid, alcohol and acetone) of iron(III) nitrite respectively. The characterization of catalyst by means of XPS, Mössbauer spectroscopy, TPR and CO hydrogenation is reported. The catalyst prepared with the aqueous solution has no activity for CO hydrogenation because the Fe(III) in the catalyst cannot be reduced to -Fe. However, the catalysts prepared with organic solution possess obvious hydrogenation activity, in which -Fe is present in the initial reduced catalyst besides Fe3+ and Fe2+. The results may be explained by the interaction degrees between the metal and the support induced by the different impregnation solvents. 相似文献