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111.
Summary A simple and general method for the determination of both C1−C10 alkyl sulfonates and alkyl carboxylates using the same basic methodology, based on High Performance ion Chromatography, using
relatively simple eluent systems allowing fast analysis with both high sensitivity and accuracy is presented. 相似文献
112.
含铁离子的XO/HX体系对糖类分子氧化作用的ESR研究 总被引:1,自引:0,他引:1
用自旋俘获方法直接检测含铁的黄嘌呤氧化酶/次黄嘌呤体系中由糖产生的自由基,发现该体系中除了产生羟基自由基外,还产生烷(氧)基自由基,且糖的浓度越高,体系中产生的烷(氧)基自由基也越多.这表明含铁的黄嘌呤氧化酶/次黄嘌呤体系对糖类分子有氧化作用,且糖的浓度越高,氧化作用越强,对机体的损伤越大.应用含硒抗体酶可有效清除烷(氧)基自由基,显示出很强的抗氧化能力. 相似文献
113.
烷基聚葡糖苷溶液的表面吸附平衡与动力学 总被引:3,自引:0,他引:3
用吊片法和气泡最大压力法分别测定了烷基聚葡糖苷(APG)C9.6G1.3水溶液的平衡和动态表面张力,研究了APG水溶液表面的吸附平衡、动力学及其影响因素.测得其cmc(临界胶束浓度)为0.032g/L.吸附过程由初始的扩散控制转变到势垒控制,吸附势垒为4~7kJ/mol.温度升高,平衡和动态表面张力均减小,吸附量增加;加入无机盐,平衡和动态表面张力增大,吸附量亦增加;醇类的吸附使动态表面张力下降速率加快,表明APG与醇分子间有协同吸附作用. 相似文献
114.
GAO Jie MENG Ye ZHAO Weiwei JIANG Daofa JIN Yanmei ZHENG Jun YANG Xinan MA Peihua 《高等学校化学研究》2021,37(3):674-678
The host-guest interactions between cyclopentanocucurbit-[6]uril(CyP6Q[6]) as host and six alkyl imidazolium hydrochloride as guests(g1, g2, g3, g4, g5, and g6) have been studied by various techniques, such as 1H NMR spectroscopy, isothermal titration calorimetry, mass spectrometry, and single-crystal X-ray diffraction analysis. The experimental results showed that CyP6Q[6] formed 1:1 inclusion complexes with each of guests g1-g6. The part of the guest entered the cavity of CyP6Q[6] changes as the alkyl chain increases in length. It can be seen that the length of the alkyl chain plays a key role in determining the mode of host-guest interactions. 相似文献
115.
A rapid and highly efficient method for the radical formation using potassium alkylfluoroborates as radical precursor is devised and developed which conducts under relatively mild condition using silver(I) oxide as the oxidant. The observed silver mirror phenomenon hints at the fact that Ag2O is the real oxidant. This approach effectively overcomes the drawbacks-stringent reaction conditions and poor tolerance of a variety of functional groups. 相似文献
116.
n-C
12
H
25
(OC
2
H
4
)
4
SO
4
Na micelles have been investigated by small angle neutron scattering technique. Results have been obtained for a series of solutions of variable concentration of surfactant and for an approximately 0.07M solution to which different amounts of NaCl were added. Micellar parameters, aggregation number, and apparent charge have been compared to those previously obtained for C
12
H
25
(OC
2
H
4
)
4
SO
4
Na. On changing the surfactant concentration, the growth gradient of micelles of the latter is similar to the growth gradient of micelles of C
12
H
25
(OC
2
H
4
)
4
SO
4
Na when no excess salt is present. In the presence of added electrolyte, C
12
H
25
(OC
2
H
4
)
2
SO
4
has a higher growth gradient than C
12
H
25
(OC
2
H
4
)
4
SO
4
. This result has been interpreted in terms of effect of the oxyethylene group. The monodisperse core+shell spherical model of micellar structure previously proposed for this class of surfactant seems to hold in a wide range of concentrations of surfactant and/or added electrolyte. 相似文献
117.
The adsorption and surface reactions of propyl iodide on clean and potassium-modified Mo2C/Mo(1 0 0) surfaces have been investigated by thermal desorption spectroscopy (TPD), X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS) in the 100-1200 K temperature range. This work is strongly related to the better understanding of the catalytic effect of Mo2C in the conversion of hydrocarbons. Potassium was found to be an effective promoter: it induced the rupture of C-I bond in the adsorbed C3H7I even at 100 K. The extent of C-I bond scission varied approximately linearly with the concentration of K coverage at the adsorption temperature of 100 K. As revealed by HREELS and TPD measurements the primary products of the dissociation are C3H7 and I. The former one was stabilized by potassium and underwent dehydrogenation and hydrogenation to give propene and propane. The desorption of both compounds is reaction-limited process. A fraction of propyl groups was converted into di-σ-bonded propene, which was stable up to ∼380 K. The coupling reaction of propyl species was also facilitated by potassium and resulted in the formation of hexane and hexene with Tp ∼ 230-250 K. Hydrogen was released with Tp = 390 K, indicative of a desorption limited process. The effect of potassium was explained by the extended electron donation to adsorbed propyl iodide in one hand, and by the direct interaction between potassium and I on the other hand. This was reflected by the shift of the desorption of potassium from the coadsorbed layer at and above 1.0 ML to higher temperature, and by the coincidal Tp values (∼700 K) of potassium and iodine. The formation of KI was also supported by the appearance of a loss feature at 650 cm−1 in the HREEL spectra attributed to a phonon mode of KI. 相似文献
118.
M. Pursch R. Brindle A. Ellwanger L. C. Sander C. M. Bell H. Hndel K. Albert 《Solid state nuclear magnetic resonance》1997,9(2-4):191-201
Stationary interphases with long n-alkyl chains (n = 18, 22, 30, 34) have been examined by solid-state NMR spectroscopy. The determination of the silane functionality and the degree of cross-linking of silane ligands on the silica surface was performed by 29Si CP/MAS NMR spectroscopy. High-speed 1H MAS and 13C CP/MAS NMR spectroscopy were utilized to assess alkyl chain order and mobility of the different bonded phases. For this purpose, 1H NMR line widths and 13C chemical shifts have been evaluated. It is shown that stationary phase order and rigidity increase with alkyl chain length. In addition, the temperature-dependent trans/gauche conformational change occurs at higher temperatures for a polymeric C34 phase compared with a C30 sorbent. This behaviour is discussed in the context of previously reported Chromatographic (HPLC) shape selectivity differences. 相似文献
119.
Takushi Azemi 《Tetrahedron》2004,60(6):1339-1344
Cyclopentane and cyclohexane derivatives are prepared from 1,5- and 1,6-dienes in a one pot procedure by hydrozirconation, then oxidation of the generated 5- and 6-alkenylzirconocene chlorides with ammonium hexanitratocerate. 相似文献
120.
Issa?YavariEmail author Azizollah?Habibi Mohammad R.?Hosseini-Tabatabaei Hamid R.?Bijanzadeh 《Monatshefte für Chemie / Chemical Monthly》2003,134(12):1651-1658
Summary. 5-Isopropylidene-2,2-dimethyl-1,3-dioxane-4,6-dione (the condensation product of Meldrums acid and acetone) reacts smoothly with tert-butyl isocyanide in the presence of primary or secondary amines to produce N-tert-butyl-2,2-dimethylbutyramide derivatives and/or 1-tert-butyl-4,4-dimethyl-2,5-dioxopyrrolidine-3-carboxamides in good yields. 相似文献