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991.
In this paper, (vapour + liquid) equilibrium (VLE) for the {1,1-difluoroethane (R152a) + 1,1,1,3,3-pentafluoropropane (R245fa)} system was determined by a static-analytical method at T = (323.150 to 353.150) K. Values of the VLE were correlated by the Peng–Robison equation of state (PR EoS) using two different models, the van der Waals (vdWs) mixing rule and the Huron–Vidal (HV) mixing rule involving the non-random two-liquid (NRTL) activity coefficient model. The correlated results show good agreement with the experimental values. For the two models, the maximum average absolute deviations of the vapour phase mole fraction are 0.0034 and 0.0035, respectively. 相似文献
992.
993.
A thorough understanding of amino acid adsorption by mineral and oxide surfaces has a major impact on a variety of industrial and biomedical applications. Little information currently exists regarding temperature effects on most of these adsorption processes. Deeper thermodynamic analyses of their multiple temperature adsorption isotherms would aid the interpretation of the interfacial interactions. Low solution concentration adsorption isotherms for glycine, lysine and glutamic acid on a silica adsorbent were generated for T = (291, 298 and 310) K. Data analysis via the Clausius–Clapeyron method yielded the isosteric heat of adsorption as a function of fractional monolayer coverage for each adsorptive. Each amino acid showed an exothermic adsorption response. Glycine and lysine experienced a greater negative effect of increased temperature compared with glutamic acid, indicating a greater number of adsorbed molecules than glutamic acid, with the former undergoing intermolecular clustering within the adsorbed phase. Isosteric heat analyses suggest ionic interactions for lysine and hydrogen bonding for glutamic acid, both weakening with increased coverage. In contrast, initial hydrogen bonding led to ionic bonding for glycine with increasing coverage. 相似文献
994.
Vasylyna Lavra Yaroslav Bazel Miroslav Badida Vasil Andruch 《International journal of environmental analytical chemistry》2015,95(3):217-224
A novel and simple procedure for determination of anionic surfactants has been developed. The method is based on the reaction of sodium dodecyl sulphate (SDS) with Astra Phloxine FF reagent at pH 3–8, followed by liquid–liquid microextraction of the formed ion associate into an organic phase containing a mixture of carbon tetrachloride and dichloroethane (4:1, v/v) and subsequent UV-Vis detection at 555 nm. The calibration plot was linear in the range 0.006–0.29 mg L?1 of SDS. The limit of detection (LOD), calculated based on 3s, is 0.002 mg L?1. The method was applied to the determination of anionic surfactants in real wastewater samples. 相似文献
995.
利用高效液相色谱(HPLC)对喹啉黄各组分进行分离并定量,通过液相色谱–串联质谱(LC–MS/MS)对各组分进行定性。以0.01 mol/L乙酸铵溶液和甲醇为流动相进行梯度洗脱,利用Agilent XDB–C18色谱柱对喹啉黄各组分进行分离,峰面积归一化法定量。质谱采用电喷雾负离子(ESI–)模式电离,多反应监测(MRM)模式检测,对喹啉黄各组分进行定性。结果表明,喹啉黄主要成分为喹啉黄一钠盐和喹啉黄二钠盐,分别各有两种同分异构体,各组分质量浓度在5.0~100.0μg/m L范围内与峰面积呈良好的线性关系。加标回收率为98.2%~99.1%,测定结果的相对标准偏差为0.90%~1.58%(n=6)。该方法具有良好的精密度和准确度,可用于喹啉黄中各组分的测定。 相似文献
996.
将色谱–光谱仪联用(HPLC–UV)法与斜投影法结合,建立了丹皮酚含量快速分析方法。通过色谱–光谱联用采集丹皮酚结晶母液的紫外多波长光谱三维数据,构建不含丹皮酚的背景数据库以及丹皮酚光谱数据库,基于斜投影法步骤测定了批量样本中丹皮酚含量。结果表明:该方法计算结果和高效液相色谱分析结果接近,相对误差小于5.0%。测定结果的相对标准偏差为0.4%~1.0%(n=5),回收率为98.8%~101.3%。该方法快速、准确,操作简单,可为丹皮酚结晶产品及各种制剂质量控制提供可行方案。 相似文献
997.
Bo Xiang 《International Journal of Polymer Analysis and Characterization》2017,22(6):534-544
Acrylonitrile-styrene-acrylate (ASA) with controllable core–shell structure was prepared through three-stage seeded emulsion polymerization. A series of characterizations had been performed to study the effect of different core–shell ratios on the properties of ASA. The most interesting was that the impact strength of ASA exhibited a “wave” variation instead of a linear variation with the increasing loading content of poly(butyl acrylate) (PBA) core. Moreover, the threshold of impact strength appeared at 49.725?wt% PBA content, nearly 33 kJ/m2. To explain this unusual variation, an impact schematic was proposed. 相似文献
998.
V. D. Krasikov Y. V. Pokhvoshchev I. I. Malakhova N. I. Gorshkov N. S. Gulii I. V. Podeshvo 《International Journal of Polymer Analysis and Characterization》2017,22(5):375-382
Structural, molecular, and hydrodynamic characteristics of thermostable functionalized polymers [polyamic acids (PAAs) with biquinoline chelate groups in the main chain] were studied by high-performance liquid chromatography. Size exclusion mechanism of chromatography in conditions including suppression of polyelectrolyte swelling and ion-exclusion effects was proved. The influence of molecular and structural characteristics of PAAs on their ability to form metal–polymer complexes (MPCs) with copper(I) chloride was studied. The critical polymer concentration at which binding of two PAA macromolecules with Cu+ ion takes place to form MPCs was estimated. 相似文献
999.
Adriana Popa Smaranda Iliescu Nicolae Doca Titus Vlase Gabriela Vlase 《International Journal of Polymer Analysis and Characterization》2017,22(1):43-50
A commercial styrene–divinylbenzene copolymer was functionalized by multistep reactions with alpha-isopropylaminophosphonic acid groups. Three different functionalized copolymers were obtained in which the phosphonic groups are in meta (1E), para (2E), and ortho (3E) positions. The thermal behavior was studied using the TG/IR hyphenated technique and kinetic analysis of thermo-oxidation under nonisothermal conditions. The evolved gas analysis confirms the partial thermo-oxidative degradation of polymeric materials, with significant preservation of the aromatic ring. The kinetic analysis was performed by three methods: Friedman, Flynn–Wall–Ozawa, and nonparametric kinetic. 相似文献
1000.