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221.
Wang Q Zhu L Li G Tu C Pang Y Jin C Zhu B Zhu X Liu Y 《Macromolecular bioscience》2011,11(11):1553-1562
A novel type of drug carrier capable of controlled drug release is proposed. It consists of an acid-sensitive doubly hydrophilic multiarm hyperbranched copolymer with a hyperbranched polyamidoamine core and many linear poly(ethylene glycol) arms. Using pH-sensitive acylhydrazone linkages, the polymer forms unimolecular micelles that can encapsulate hydrophobic drugs. Due to their amphiphilicity, the drug-loaded unimolecular micelles can self-assemble into multimolecular micelles that show acid-triggered intracellular delivery of the hydrophobic drugs. 相似文献
222.
Desalting peptides before mass spectrometry analysis is important because salts lead to adduct formation, increased chemical noise and ion suppression effect. A high concentration of salt can clog nanoelectrospray ionization (ESI) emitters. The reverse phase C18 material is commonly used to desalt peptides because of its high binding capacity. However, peptides with high hydrophilicity, such as glycopeptides, are not retained well on this material, resulting in the loss of peptide information. To improve the efficiency of glycopeptide desalting, we introduced a hydrophilic interaction chromatography (HILIC)-based material named click maltose. Four glycoproteins, horseradish peroxidase (HRP), human serum immunoglobulin G (IgG), bovine ribonuclease B (RNase B), and α-1 acid glycoprotein (AGP) were chosen as models and their glycopeptides were desalted with click maltose, AQ C18, Empore C18 and ZipTip C18. Click maltose as a HILIC material exhibited better performance than the other three C18 materials for both number of targeted glycopeptides and their corresponding intensities. In addition, accurate glycopeptide profiling was achieved with click maltose desalting regardless of peptide lengths and glycan types. 相似文献
223.
224.
Junwei Zhao Qiuxia Han Dongying Shi Lijuan Chen Pengtao Ma Jingping Wang Jingyang Niu 《Journal of solid state chemistry》2011,184(10):2756-2761
A S-shaped multi-iron substituted arsenotungstate [enH2]2[(α-H2AsVW6O26)Fe3(H2O)(B-α-H4AsVW9O34)]2[Fe]2·8H2O (1) (en=ethylenediamine) has been prepared by reaction of K14[As2IIIW19O67(H2O)]·nH2O with Fe2(SO4)3·xH2O under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, UV spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The skeleton of 1 consists of two asymmetric sandwich-type subunits [(α-H2AsVW6O26)Fe3(H2O)(B-α-H4AsVW9O34)]5− linked by a di-FeIII cluster. Moreover, magnetic susceptibility measurements demonstrate that 1 indicates the antiferromagnetic coupling interactions within FeIII centers with the best-fitting set of parameters of J1=−7.07 cm−1, J2=−0.45 cm−1 and g=2.05, which are generated by the addition of the expressions of the molar susceptibilities of two tri-FeIII clusters and one di-FeIII cluster derived from for spin pairs coupled through the isotropic exchange interactions. 相似文献
225.
微波消解/ICP MS法测定不同地点虎耳草中16种元素含量 总被引:1,自引:0,他引:1
利用微波消解/ICP-MS法对3个地点虎耳草中16种元素进行了含量测定.结果表明,不同地点虎耳草元素的含量相差较大,虎耳草中Ca元素与海拔高度呈线性关系.该法的加样回收率在95.3%~105.0%之间,相对标准偏差在0.98%~2.82%之间,具有较高的准确度和精确度.结果为虎耳草的药效性和药理毒理提供了理论依据. 相似文献
226.
Wu Y Jiang F Chen L Zheng J Deng Z Tao Q Zhang J Han L Wei X Yu A Zhang H 《Analytical and bioanalytical chemistry》2011,400(7):2141-2147
A new micellar electrokinetic chromatography (MEKC) method using beta-cyclodextrins (β-CDs) and 1-butyl-3-methylimidazolium hexafluorophosphates (ionic liquids) as additives was successfully developed for determination of para-, meta-, and ortho-phenylenediamines isomers (p-P, m-P, and o-P) in hair dyes. To improve the sensitivity of the MEKC-UV, a simple and cheap flow injection (FI) technique using a micro-column packed with coal cinders (the by-products from combustion in a boiler) as solid-phase extractant was also investigated. In the presence of 20 mmol L(-1) phosphates at pH 5.5, addition of 12 mmol L(-1) ionic liquids and 8 mmol L(-1) β-CDs greatly improved the separation efficiency. The three analytes could be quantitatively adsorbed by coal cinders, and desorbed readily with 0.15 mL of 0.01 mol L(-1) NaOH. Under the optimum conditions, an enrichment factor (EF) of 33.3 was obtained, and determination limits of p-P, m-P, and o-P were 1.97?×?10(-7), 0.99?×?10(-7), and 0.61?×?10(-7) mol L(-1), respectively. The adsorption capacities of the coal cinders micro-column for p-P, m-P, and o-P were all 1.20 mg g(-1). The presented procedure was successfully applied to the determination of p-P, m-P, and o-P in hair dyes with satisfactory results. 相似文献
227.
Xintao Wang Feng Qin Lijuan Jing Qiang Zhu Famei Li Zhili Xiong 《Biomedical chromatography : BMC》2013,27(3):371-376
A sensitive, rapid and selective ultra‐performance liquid chromatography–tandem mass spectrometric (UPLC‐MS/MS) method was developed for the determination and pharmacokinetic study of domperidone in human plasma. Diphenhydramine was used as the internal standard. Plasma sample pretreatment involved a one‐step liquid–liquid extraction with a mixture of diethyl ether–dichloromethane (3:2, v/v). The analysis was carried out on an Acquity UPLCTM BEH C18 column. The mobile phase consisted of methanol–water containing 10 mmol/L ammonium acetate and 0.5% (v/v) formic acid (60:40, v/v). The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode via electrospray ionizationsource with positive mode. Each plasma sample was chromatographed within 2.1 min. The standard curves for domperidone were linear (r2 ≥ 0.99) over the concentration range of 0.030–31.5 ng/mL with a lower limit of quantification of 0.030 ng/mL. The intra‐ and inter‐day precision (relative standard deviation) values were not higher than 13% and accuracy (relative error) was from ?7.6 to 1.2% at three quality control levels. The method herein described was superior to previous methods and was successfully applied to the pharmacokinetic study of domperidone in healthy Chinese volunteers after oral administration. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
228.
Liquid–liquid equilibria data of the quaternary system methyl isobutyl ketone (MIBK)–water–phenol–hydroquinone were measured at 25 °C under atmosphere pressure. The experimental data were correlated with the UNIQUAC and NRTL activity coefficient models on the base of the fixed binary interaction parameters that were obtained from two sub-ternary systems MIBK–water–phenol and MIBK–water–hydroquinone. The root mean square deviations (RMSD) show that the regressed results for the quaternary system were in good agreement with the experimental data for both UNIQUAC and NRTL models. The comparison between experimental and calculated distribution coefficient values of phenol and hydroquinone shows that a relative deviation of less than 5% is obtained. 相似文献
229.
Gao F Tang L Dai L Wang L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(2):517-521
We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors. 相似文献
230.