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1.
异丙苯在Cu-HMS分子筛上的催化氧化 总被引:3,自引:2,他引:1
以含Cu的中孔分子筛(Cu-HMS)为催化剂,研究异丙苯的催化氧化。研究发现,Cu-HMS催化剂的加入使异丙苯氧化的诱导期显著缩短。在75℃下,以Cu-HMS为催化剂,O2为氧化剂的纯异丙苯氧化反应,苯乙酮为主要副产物,反应的选择性和转化率都很高。当催化剂用量为1 5×10-4mol/ml时,反应8h后,异丙苯转化率为32 7%,目的产物的累积浓度(质量分数)为37 7%,选择性为99%;反应12h后,异丙苯转化率为42 4%,目的产物的累积浓度为46 3%,选择性为95 6%。 相似文献
2.
A ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (Tg) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed. © 2003 Society of Chemical Industry 相似文献
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The phase behavior and motional mobility in binary blends of polystyrene (PS) and poly(cyclohexyl methacrylate) (PCHMA) have been investigated by solid state 13C NMR techniques. The blend miscibility has been studied by examining the 1H spin-relaxation times in the laboratory frame (T1H) and in the rotating frame (T1ρH) for the PCHMA/PS blends with various compositions and pure components. The T1ρH results show that PCHMA and PS are intimately mixed at the molecular level within the blends at all compositions. In addition, according to the results of carbon T1ρ relaxation time measurements, we conclude that mixing is intimate enough to cause a reduction in local chain mobility for PS, but an increase in side chain mobility for PCHMA. 相似文献
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双核中性镍催化剂的合成及催化乙烯聚合研究 总被引:2,自引:0,他引:2
经烷基化、甲酰化、Schiff碱缩合反应,制得两种水杨醛亚胺配体(7)和(8),并与 trans[NiCl(Ph)(PPh3)2] 反应合成了两种中性镍配合物:(9){[[O-(3-Cyclohexanyl)(5-CH3)C6H2-ortho-C(H)=N-2,6-C6H3(i-Pr)2]Ni(Ph3P)(Ph)]2CH2}和(10){[[O-(3-Cyclohexanyl)(5-Cl)C6H2-ortho-C(H)=N-2,6-C6H3(i-Pr)2]Ni(Ph3P)(Ph)-2-CH2},以GC-MS,1H NMR对中间产物及配合物进行了表征.在Ni(COD)2的助催化作用下,配合物(9)和(10)能有效催化乙烯聚合.在8.0×105 Pa的压力下,配合物(9)的最高活性可达5.34×105 g /(mol·h),聚乙烯相对分子质量和相对分子质量分布分别为5.26×104和 2.39.配合物(10)的最高活性可达5.74×105g /(mol·h),聚乙烯相对分子质量和相对分子质量分布分别为8.61×104和2.81. 相似文献
7.
环己苯和三乙胺对锂离子蓄电池的过充保护 总被引:1,自引:0,他引:1
用循环伏安、充放电仪、扫描电子显微镜(SEM)等方法研究了环己苯和三乙胺对锂离子蓄电池的过充保护作用以及对电池综合电性能的影响。研究表明,环己苯在4.7V(vs.Li/Li )发生电聚合反应,生成导电聚合物膜聚环己苯使电池自放电至安全状态,防止了电池的过充;三乙胺与氢质子反应,不但提高了电池的过充能力,而且有效地抑制了电池的膨胀;环己苯与三乙胺的联合应用可使方型锂离子蓄电池(型号:063048)耐2C-10V的过充;在正常充放电状态下,环己苯的加入不影响电池的综合电性能。 相似文献
8.
建立了丙烯环氧化反应中叔丁基过氧化氢(TBHP)的高效液相色谱分析方法。考察了色谱柱类型、流动相配比和检测器紫外吸收波长对测定结果的影响,得到了高效液相色谱法测定TBHP含量的适宜分析条件。即采用Hypersil NH2正相色谱柱(250 mm×4.6 mm×5μm),以体积比80∶20的乙腈-二氯甲烷混合溶液为流动相,流量1.0 mL/min,柱温30℃,紫外检测波长222 nm。测试结果表明,丙烯环氧化反应产物中的组分在4 min内可完全出峰,并得到良好的分离;TBHP质量浓度在0.17~17.30 mg/mL内时,其与峰面积呈现良好的线性关系,相关系数r=0.999 9,检出限为3.46μg/mL,加标回收率达99.4%~101.2%。该分析方法准确、快速且灵敏度较高。 相似文献
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Effect of natural antioxidants in virgin olive oil on oxidative stability of refined,bleached, and deodorized olive oil 总被引:1,自引:0,他引:1
M. Teresa Satue Shu-Wen Huang Edwin N. Frankel 《Journal of the American Oil Chemists' Society》1995,72(10):1131-1137
The factors influencing the oxidative stability of different commercial olive oils were evaluated. Comparisons were made of
(i) the oxidative stability of commercial olive oils with that of a refined, bleached, and deodorized (RBD) olive oil, and
(ii) the antioxidant activity of a mixture of phenolic compounds extracted from virgin olive oil with that of pure compounds
andα-tocopherol added to RBD olive oil. The progress of oxidation at 60°C was followed by measuring both the formation (peroxide
value, PV) and the decomposition (hexanal and volatiles) of hydroperoxides. The trends in antioxidant activity were different
according to whether PV or hexanal were measured. Although the virgin olive oils contained higher levels of phenolic compounds
than did the refined and RBD oils, their oxidative stability was significantly decreased by their high initial PV. Phenolic
compounds extracted from virgin olive oils increased the oxidative stability of RBD olive oil. On the basis of PV, the phenol
extract had the best antioxidant activity at 50 ppm, as gallic acid equivalents, but on the basis of hexanal formation, better
antioxidant activity was observed at 100 and 200 ppm.α-Tocopherol behaved as a prooxidant at high concentrations (>250 ppm) on the basis of PV, but was more effective than the
other antioxidants in inhibiting hexanal formation in RBD olive oil.o-Diphenols (caffeic acid) and, to a lesser extent, substitutedo-diphenols (ferulic and vanillic acids), showed better antioxidant activity than monophenols (p- ando-coumaric), based on both PV and hexanal formation. This study emphasizes the need to measure at least two oxidation parameters
to better evaluate antioxidants and the oxidative stability of olive oils. The antioxidant effectiveness of phenolic compounds
in virgin olive oils can be significantly diminished in oils if their initial PV are too high. 相似文献