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排序方式: 共有249条查询结果,搜索用时 15 毫秒
141.
Acrylamide concentrations in grilled foodstuffs of Turkish kitchen by high performance liquid chromatography-mass spectrometry 总被引:3,自引:0,他引:3
Olcay Kaplan Gokce Kaya Cemile Ozcan Muharrem Ince Mehmet Yaman 《Microchemical Journal》2009,93(2):173-179
For over ten years, there has been a considerable interest in determination of acrylamide in foodstuffs. It was known that both protein-rich and carbohydrates-rich foods cooked at high-temperatures can cause acrylamide formation. However, carbohydrates-rich foods such as potato chips and biscuit samples have been the common studied foods compared with protein-rich foods such as meat samples.In this study, determination of acrylamide in these two group foods was examined using HPLC-MS. For this purpose, firstly, the parameters that are thought to affect the response in the HPLC-MS analysis were optimized. The optimized conditions were found to be 0.3 ml min− 1 for flow rate of mobile phase, 40 µl for injection volume, 5 °C for column temperature and 70 V for fragmentor potential. The optimized method was applied for the determination of acrylamide levels in Turkish foodstuffs including grilled meat and chicken samples, potato chips, coffee and biscuit. The obtained concentrations for all studied foods were in the range of 20–250 µg kg− 1. The results showed that acrylamide concentrations highly varied depending on the kind of food samples. 相似文献
142.
An acrylamide(AM)-based ter-polymer (PAAB) containing sodium 2-acrylamido-2-methylpropane sulphonate (NaAMPS) and p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VBE, polymerization degree: 24) was synthesized by an aqueous free-radical copolymerization. In order to obtain a PAAB polymer with both good thickening properties and surface and interfacial properties in brine solutions for enhanced oil recovery (EOR), the influences of the NaAMPS and VBE feed amounts on the intrinsic and apparent viscosities and the surface and interfacial tensions of the PAAB polymer in aqueous solutions were investigated. The optimum NaAMPS feed amount was 9 mol%; an excessive feed amount interfered with the aggregations of the PAAB macro-molecules in aqueous solutions and on the surfaces of aqueous solutions and the interfaces between aqueous solutions and kerosene. In addition, for this NaAMPS feed concentration, the PAAB polymer showed the highest apparent viscosities and the lowest surface and interfacial tensions in 5 g L?1 NaCl for a VBE feed amount of 1.1 mol%. The mechanism giving rise to the solution properties for this polymer was examined. For this purpose, the effect of the polymer concentration on the supra-molecular structures of the PAAB polymer in water and in 5 g/L NaCl, were investigated by ultraviolet spectral analysis using pyrene as a probe. A transmission electron microscope (TEM) was also used to observe the morphologies of the associated structures in aqueous solutions to explore the correlation between the solution properties and solution structures for PAAB; expanded polymer chain bundles were formed at a polymer concentration of 0. 4 g L?1, higher than the critical micelle concentration (0. 3 g L?1). 相似文献
143.
Summary Two liquid chromatographic methods are described for the separation and determination of components in the production of acrylamide by the catalytic hydration of acrylonitrile. The first of these provides a rapid technique by which concentrations and conversion can be directly determined for process control applications, whilst the second represents a more rigorous separation of all possible impurities for quality control purposes. 相似文献
144.
Demet Topaloğlu Yazıcı Hayrullah Çetinkaya Musa Şölener Adile Albayrak 《International Journal of Polymer Analysis and Characterization》2017,22(6):483-489
The surface properties of newly synthesized N-methoxy isopropyl acrylamide, N-methoxy isopropyl methacrylamide, cyclo propyl acrylamide, and cyclo propyl methacrylamide polymers were investigated using inverse gas chromatography. The highest dispersive component of the surface energy value was obtained for cyclo propyl methacrylamide at 30°C. The values obtained for all polymers were decreasing with the increasing temperature. The values obtained for the acidic and the basic parameters revealed strong basic characters for the surface of N-methoxy isopropyl methacrylamide and cyclo propyl methacrylamide polymers and weak basic characters for the surface of N-methoxy isopropyl acrylamide and cyclo propyl acrylamide polymers. 相似文献
145.
《Electroanalysis》2017,29(11):2572-2578
We report in this work, a new method for the determination of captopril by differential pulse voltammetry using a glassy carbon electrode modified with a copper metal‐organic framework (H‐Kust‐1 or Cu3(BTC)2 or Cu‐BTC), immobilized on the surface by a copolymer of acrylamide and sodium acrylate. This compound is detected by the formation of a copper(II)‐captopril complex that is observed in an oxidation potential at ca. +0.28 V vs . Ag/AgCl. A linear dynamic range is obtained for a captopril concentration of 0.5 μM to 7.0 μM and the voltammetric response is highly reproducible within 3.52 % error. The sensitivity of 9.71±0.37 nA μM−1 and the limit of detection of 0.20±0.01 μM make this methodology highly applicable for practical applications. The determination of captopril in a commercial pharmaceutical sample showed a recovery of 93.3 %. 相似文献
146.
以偶氮二异丁腈为引发剂,采用沉淀聚合法在低毒性溶剂乙醇中制备出了平均粒径在2.933μm~4.742μm之间的聚(丙烯酰胺-二乙烯基苯)微球。通过粒度分析、电镜扫描、热重分析,研究不同因素对反应产物的形态和耐温性的影响发现:只有当温度为70℃,交联单体二乙烯基苯的加量控制在25%~50%之间,单体浓度低于4%时,反应才可得到形状规则的微球;增加单体中二乙烯基苯的含量有利于增加微球的耐温性,微球耐温可高达320℃;延长反应时间有利于增大微球粒径,增加引发剂用量有利于降低微球粒径,但二者均能增加微球的产率。 相似文献
147.
我们曾经报道过硫酸盐和脂肪族六元环胺可以组成氧化还原引发体系用于烯类单体水溶液聚合,并且证实环仲胺如吗啉(MP)和哌啶(PD)被氧化后生成氮自由基参与了引发反应。本文对过硫酸盐和五元环胺吡咯烷(PyD)组成的引发体系进行了研究。 1 实验部分 相似文献
148.
通过丙烯酰胺、二氰二胺、甲醛及氯化铵的缩合反应,合成了分子链端含C=C双键的大单体,缩合过程用高压液相色谱考察,以AIBN为引发剂,二甲基亚砜为溶剂,使大单体与苯乙烯共聚,得到主链具有疏水性、侧链具有亲水性的共聚物,用GPC、IR光谱及溶解性对共聚物进行鉴定,苯乙烯含量较低时,共聚物溶于水,共聚物在MeOH/H2O混合溶剂中的粘性行为表明它是带有疏水基团的聚电解质。 相似文献
149.
在实施丙烯酰胺型阴离子表面活性单体2-丙烯酰胺基十四烷磺酸钠(NaAMC14S)与丙烯酰胺(AM)水溶液均相共聚合过程中,分别通过改变AM与NaAMC14S的投料比、改变外加电解质NaCl的加入量以及引发剂的用量,制备了分子链微结构系列变化的具有微嵌段结构的共聚物NaAMC14S/AM;采用荧光探针法与表观粘度法研究了共聚物分子链微结构与其疏水缔合性能之间关系,探索了共聚物分子链中疏水微嵌段含量、疏水微嵌段长度及共聚物分子量诸微结构因数对共聚物疏水缔合性的影响.结果表明,共聚物NaAMC14S/AM的疏水缔合性随着疏水微嵌段含量的增加而增强,随着疏水微嵌段长度的增长而增强,当疏水微嵌段含量和嵌段长度一定时,共聚物的疏水缔合性随分子量的增大而增强. 相似文献
150.
Emulsifier-free emulsion copolymerization of styrene and acrylamide using an amphoteric initiator 总被引:2,自引:0,他引:2
S.-J. Fang K. Fujimoto S. Kondo K. Shiraki H. Kawaguchi 《Colloid and polymer science》2000,278(9):864-871
Emulsifier-free emulsion copolymerization of styrene (St) and acrylamide (AAm) has been investigated in the presence of an
amphoteric water-soluble initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine]hydrate (VA057). The kinetics of polymerization and the colloidal properties of
the resulting latices were studied and compared with the cases using ionic initiators. When adopting the amphoteric initiator
at pHs lower than 10, stable amphoteric poly (St/AAm) latices, evidenced by the electrophoretic mobility, were prepared directly.
Meanwhile, almost the same conversion versus time curves appeared and there were no apparent differences in the final particle
sizes for those polymerizations, whereas in the polymerization at pH 10, a much lower rate of copolymerization and a larger
size of particles were observed. The surface charge density and the growth rate of latex particles produced with VA057 at
pH<10 were comparable to those of the particles with a cationic initiator, 2,2′-azobis(2-amidinopropane)dihydrochloride, but
were apparently lower than those with an anionic initiator, potassium persulfate, when the polymerizations were carried out
under corresponding conditions. The number of initiator fragments incorporated onto the particle surfaces was independent
of polymerization pH, except for pH 10. The abnormal performance of VA057 at pH 10 was attributed to its degradation due to
hydrolysis.
Received: 14 December 1999 Accepted: 22 February 2000 相似文献