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71.
Jayrang S. Dave Meera R. Menon Pratik R. Patel 《Molecular Crystals and Liquid Crystals》2013,570(1):575-587
Abstract Chiral liquid crystals have attracted considerable interest as they exhibit a good variety of modulated phases. We have synthesised a homologous series viz., 4-(4!-n-alkoxy benzoyloxy) benzylidene-4!!?1-(s)-methyl propoxy anilines, incorporating a terminal chiral centre, inorder to obtain better understanding of the relationship between molecular structure and appearance of SmC* phase in the molecules. It is observed that, in the present series the lower members upto butyl are pure nematogens, while pentyl to hexadecyl derivatives exhibit classical smectic as well as nematic mesophases. An additional smectic C* phase is observed in the middle octyl to dodecyl homologues. The homologues have been characterised by IR, NMR and DSC. Their mesomorphic properties have been compared with structurally related homologous series. 相似文献
72.
73.
HYDROGENATION OF NITROBENZENE TO FORM ANILINE IN LIQUID PHASE AT ATMOSPHERIC PRESSURE* 总被引:1,自引:0,他引:1
YIN Jingbo YANG Yana Zhubanov K. A Bizhanowa N. B Jilin Institute of Technology Changchun China Kazakstan National University Alma-Ata Kazakstan 《Chinese Journal of Reactive Polymers》2001,(1)
1. EXPERIMENT SECTION1.1 Reagent and InstrumentNitrobenzene (chemical purity), alcohol (medical), hydrogen (electrolytic method 99.8%), anion exchange resin AH-1 PdCl2, 2H20 (Pd containing 59%), NaCl, LXM-80-type vapor-liquid chromatograph (made in Russia), ZD-2-type potentiometer (made in Russia). 1.2 Catalyst PreparationThere are two methods of catalyst preparation, one of which is adsorption: putting PdCl2?2H2O, AH-1, NaCl and distilled water in oscillating hydrogenation re… 相似文献
74.
在脂肪酸-水流动相中小分子在反相高效液相色谱中的保留表征 总被引:11,自引:0,他引:11
在反相液相色谱(RPLC)中用Snyder经验议程和计量置换保留模型(SDM-R)中的参数对深质为脂肪醇同系物,流动相为脂肪酸同系物时深质的保留行为进行了研究,结果表明用SDM-R参数具有明显的优越性,另外,由于用Snyder经验公式中二参数之间的作园无法准确求得斜率,且其不具有明确的物理意义,而由SDM-R二参数作图,不但能准确求得斜率j(与1mol溶剂和固相结合能有关的常数),而且j具有明确的物理意义并符合碳数规律,所以,参数j有可能用于RPLC中表征深剂强度,由此得出,在RPLC中,对同一置换剂面言,随同系物溶质的Z(1mol深剂化深质被深剂化固定相吸附时,从二接解面释放出的置换剂分子数)和logI(与1mol深质和固定相亲和势有关的常数)值增大,它们的保留时间也增大,对同一深质而言,随着在同系物置换剂中碳链的增长,Z和logI值的减小,它的保留时间也缩短,同时还可得出,随着同系物置换剂j值的减小,它们的洗脱能力也增强. 相似文献
75.
采用循环伏安法和恒电位电解法研究了离子液体EMimBF4中硝基苯在微铂电极上的选择性电还原特性. 研究结果表明, 硝基苯在铂电极上的电还原反应为双分子八电子三步骤电化学过程: 第一步反应为准可逆单电子转移步骤, 产生阴离子自由基; 第二步为二电子转移步骤, 并伴有随后的双分子不可逆自由基偶合反应和快速质子化及脱水反应, 主要产物为氧化偶氮苯; 第三步是二电子转移产生偶氮苯的过程. 通过控制电位, 可以选择性地合成氧化偶氮苯和偶氮苯; 在EMimBF4中, 硝基苯和水的浓度变化对电化学行为产生较大影响. 相似文献
76.
在气相色谱法测定溶剂型木器涂料中正丁醇及苯系物(包括苯、甲苯及二甲苯)时采用了VF-200MS型号的毛细管色谱柱。由于此型号的毛细管柱具有较强极性,不仅能达到正丁醇与苯系物之间的有效而满意的分离,而且还能使苯系物(包括苯、甲苯、乙苯、二甲苯)之间和二甲苯的同分异构体之间的有效分离。测定中采用正戊烷作内标和用火焰离子检测器检测。此方法的检出限(2S/N)在1.7~3.5 ng之间。用一含有正丁醇的硝基漆样品按所提出的方法进行多次重复测定,并在此样品的基础上加入各被测化合物的标准后进行测定,从而对方法的回收率和精密度作了测试,测得其回收率在87.8%~100.0%之间,测定值的相对标准偏差(n=6)均小于2.5%。 相似文献
77.
Tanja Kunz Dr. Claudio Schrenk Prof. Dr. Andreas Schnepf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7210-7217
The reaction system GeCl2 ⋅ dioxane/LiSTsi (Tsi=C(SiMe3)3) opens a fruitful area in germanium chemistry, depending on the stoichiometry and solvent used during the reaction. For example, the reaction of GeCl2 ⋅ dioxane in toluene with two equivalents of the thiolate gives the expected germylene Ge(STsi)2 in excellent yield. This germylene readily reacts with hydrogen and acetylene, however, in a non-selective way. By using an excess amount of the thiolate and toluene as the solvent, the germanide [Ge(STsi)3][Li(thf)] is obtained. Performing the same reaction in thf leads to a C−H activation of thf to give (H7C4O)Ge[STsi](μ2-S)2Ge[STsi]2, in which the thf molecule is still intact. Using a sub-stoichiometric amount of the thiolate leads to the heteroleptic compound [ClGe(STsi)]2 and to the insertion product (thf)Ge[S-GeCl2-Tsi]2, in which additional GeCl2 molecules insert into the C−S bonds of Ge(STsi)2. The synthesis and the experimentally determined structures of all compounds are presented together with first reactivity studies of Ge(STsi)2. 相似文献
78.
N. Moschonas D. Danalatos S. Glavas 《Monatshefte für Chemie / Chemical Monthly》1996,127(8-9):875-881
Summary The reaction of benzene with hydroxyl radicals affords phenol and 1,4-benzoquinone in 0.18±0.05 and 0.02±0.01 yield, respectively. The main reaction of the hydroxycyclohexadienyl radical with oxygen leads to the respective peroxy radical which in turn decomposes to ring cleavage products and phenol. In the presence of NO2, nitrobenzene is also formed with yields depending linearly on the initial NO2 concentration and vanishing as [NO2] approaches zero. The amount of phenol formed in the presence of NO2 is equal to that formed in the absence of NO2 within experimental error.
Der Einfluß von O2 und NO2 auf die cyclischen Produkte der Reaktion von Benzol mit Hydroxylradikalen
Zusammenfassung Die Reaktion von Benzol mit Hydroxylradikalen liefert Phenol und 1,4-Benzochinon in Ausbeuten von 0.18 ± 0.05 und 0.02 ± 0.01. Die Hauptreaktion des Hydroxycyclohexadienylradikals mit Sauerstoff führt zum entsprechenden Peroxyradikal, das seinerseits zu offenkettigen Produkten und Phenol zerfällt. In Gegenwart von NO2 entsteht Nitrobenzol; seine Ausbeute hängt linear von der Anfangskonzentration an NO2 ab und läßt sich für verschwindende NO2-Konzentrationen nach Null extrapolieren. Die Menge an gebildetem Phenol hängt nicht von der Anoder Abwesenheit von NO2 ab.相似文献
79.
Su MD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(23):6073-6084
The potential energy surfaces corresponding to the reactions of heavy carbenes with various molecules were investigated by employing computations at the B3LYP and CCSD(T) levels of theory. To understand the origin of barrier heights and reactivities, the model system (CH3)2X+Y (X=C, Si, Ge, Sn, and Pb; Y=CH4, SiH4, GeH4, CH3OH, C2H6, C2H4, and C2H2) was chosen for the present study. All reactions involve initial formation of a precursor complex, followed by a high-energy transition state, and then a final product. My theoretical investigations suggest that the heavier the X center, the larger the activation barrier, and the less exothermic (or the more endothermic) the chemical reaction. In particular, the computational results show that (CH3)2Sn does not insert readily into C-H, Si-H, C-H, Ge-H, or C-C bonds. It is also unreactive towards C=C bonds, but is reactive towards C identical with C and O-H bonds. My theoretical findings are in good agreement with experimental observations. Furthermore, a configuration mixing model based on the work of Pross and Shaik is used to rationalize the computational results. It is demonstrated that the singlet-triplet splitting of a heavy carbene (CH3)2X plays a decisive role in determining its chemical reactivity. The results obtained allow a number of predictions to be made. 相似文献
80.