全文获取类型
收费全文 | 204篇 |
免费 | 10篇 |
专业分类
化学 | 148篇 |
晶体学 | 3篇 |
力学 | 2篇 |
数学 | 28篇 |
物理学 | 33篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 5篇 |
2014年 | 15篇 |
2013年 | 32篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 11篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
排序方式: 共有214条查询结果,搜索用时 15 毫秒
41.
The effect of fermentation (retting) time and harvest time on kudzu (Pueraria lobata) fiber strength
Uludag Sibel Loha Veara Prokop Ales Tanner Robert D. 《Applied biochemistry and biotechnology》1996,57(1):75-84
Applied Biochemistry and Biotechnology - The noncommercial kudzu plant has been growing wild in the southern United States since the 1930s. In this article, the kudzu fibrous vine is investigated... 相似文献
42.
Multi-element determination of trace elements in urine and dialysis solutions by atomic absorption spectrometry has been investigated. Coprecipitation with samarium hydroxide was used for preconcentration of trace elements and elimination of matrix elements. To 10 ml of each sample was added 500 μl of 2 mg ml−1 samarium solutions; the pH was then adjusted to 12.2 in order to collect trace heavy metals on samarium hydroxide. The precipitate was separated by centrifugation and dissolved in 1 ml of 1 mol l−1 HNO3. Coprecipitation parameters and matrix effects are discussed. The precision, based on replicate analysis, is around 5% for the analytes, and recovery is quantitative, based on analysis of spiked samples and solutions including matrix components. The time required for the coprecipitation and determination was about 30 min. 相似文献
43.
S. Irem Kaya Ahmet Cetinkaya Mehmet G. Caglayan Sibel A. Ozkan 《Electrophoresis》2022,43(9-10):1035-1049
Biopharmaceuticals (recombinant technology-based products, vaccines, whole blood and blood components, gene therapy, cells, tissues, etc.,) are described as biological medical products produced from various living sources such as human, microbial, animal, and so on by manufacturing, extraction, or semi-synthesis. They are complex molecules having high molecular weights. For their safety and efficacy, their structural, clinical, physicochemical, and chemical features must be carefully controlled, and they must be well characterized by analytical techniques before the approval of the final product. Capillary electrophoresis (CE) having versatile modes can provide valuable safety and efficacy information, such as amino acid sequence, size variants (low and high molecular weight variants), charged variants (acidic and basic impurities), aggregates, N-linked glycosylation, and O-linked glycosylation. There are numerous applications of CE in the literature. In this review, the most significant and recent studies on the analysis of recombinant DNA technology-based products using different CE modes in the last ten years have been overviewed. It was seen that the researches mostly focus on the analysis of mAbs and IgG. In addition, in recent years, researchers have started to prefer CE combined mass spectrometry (MS) techniques to provide a more detailed characterization for protein and peptide fragments. 相似文献
44.
The main objective of the present paper is to investigate the Poisson distribution series for the function class \(T\left( \alpha ,\beta \right) \) of analytic functions. Moreover, we obtain necessary and sufficient conditions for the Poisson distribution series belonging to this class. We also consider an integral operator related to the Poisson distribution series. 相似文献
45.
A capillary electrophoresis method for the separation of high-molecular-mass heparin oligosaccharides compatible with mass spectral detection was developed. Structurally defined heparin oligosaccharides ranging in size from tetrasaccharide to tetradecasaccharide were used to optimize the conditions. Applying normal and reversed polarity modes, these oligosaccharides were separated by CE under various conditions. Ammonium hydrogencarbonate (30 mM at pH 8.50) used as the running electrolyte system gave good separation efficiency and resolution in the normal polarity mode. Application of this method to the separation of complicated heparin oligosaccharide mixtures required the addition of electrolyte additives. Ammonium hydrogencarbonate (30 mM), containing triethylamine (10 mM), was useful for the separation of complex oligosaccharide mixtures. Run-to-run and day-to-day precision and limits of detection were established for these separations. 相似文献
46.
Sibel Yalçin 《Analytica chimica acta》2004,505(1):25-35
Chromium may exist in environmental waters as Cr(III) and Cr(IV), the latter being the toxic and carcinogenic form. Since atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry can only yield information on total Cr concentration, a polymer resin bearing O,O-donor chelating groups such as the maleic acid-functionalized XAD(CO)CHCHCOOH resin was synthesized to selectively retain Cr(III) at pH 4.0-5.5. The dynamic breakthrough capacity of the resin for Cr(III) at pH 5.0 was 7.52 mg g−1, and the preconcentration factor extended to 250-300. Chromium(III) in the presence of 250-fold Cr(VI)—which was not retained—could be effectively preconcentrated on the NH4+-form of the resin and determined by AAS or diphenylcarbazide (DPC) spectrophotometry. When Cr(VI) was reduced to Cr(III) with Na2SO3 solution brought to pH 1 by the addition of 1 M H2SO4, and preconcentrated on the resin, total Cr could be determined. The developed method was validated with a blended coal sample CRM-1632. Since the adsorption behavior as a function of pH of possible interferent metal ions, e.g. Ni(II), Co(II), Cu(II), Cd(II), Zn(II), Pb(II) and Fe(III), was similar to that of Cr(III), selective elution of Cr(III) from the resin was realized using a mixture of 1 wt.% H2O2+1 M NH3. The eluate containing Cr as chromate could be directly analyzed by diphenyl carbazide spectrophotometry without any adverse effect from the common interferents of this method, i.e. Fe(III), Cu(II) Hg(II), VO3−, MoO42− and WO42−. Various synthetic waste solutions typical of electroplating bath effluents containing Cr, Cu, Ni, Zn, Na, Ca, cyanide (and chemical oxidation demand (COD), achieved by glucose addition) were subjected to pretreatment procedures such as hypochlorite oxidation (of cyanide) and catalytic oxidation (of COD) with peroxodisulfate. Chromium determination gave satisfactory results. The combined column preconcentration—selective elution—diphenylcarbazide spectrophotometric determination was also successfully applied to the determination of Cr in artificial and real seawater. 相似文献
47.
Nurullah Sanli Senem Sanli Umit S?z?r Mehmet Gumustas Sibel A. Ozkan 《Chromatographia》2011,73(11-12):1171-1176
The pK a values of cefdinir and cefixime, which are used in the treatment of bacterial infections, have been determined precisely in water and methanol?Cwater binary mixtures (20% v/v) using spectrophotometric titration and LC, respectively. A simple, fast and precise isocratic high-performance liquid chromatographic (LC) procedure has been developed for the determination of cefdinir and cefixime in drug formulations. This method was validated successfully for specificity, precision, linearity, range, accuracy, limit of detection, and limit of quantitation as per the ICH guidelines. The proposed method can be used for routine analysis of studied cephalosporin compounds and as an alternative tool for drug quality control laboratories. 相似文献
48.
49.
Voltammetric and liquid chromatographic (LC) methods have been developed for the simultaneous determination of amlodipine besylate (AML) and rosuvastatin calcium (ROS) for the first time. Detailed electrochemical behavior and simultaneous voltammetric determination of AML and ROS were investigated in detail using glassy carbon electrode (GCE). High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) were also developed for the comparison. Voltammetric method exhibited linear dynamic responses for the simultaneous assay of AML and ROS in the concentration range between 0.006 and 2.85 μg/mL and between 0.01 and 5.00 μg/mL, with detection limits of 0.001 and 0.003 μg/mL, respectively. On the other hand, LC methods presented a wider linearity range than that of the SWV method between 0.5 and 100 μg/mL with the detection limits of 0.011 and 0.027 μg/mL for AML and 0.034 and 0.042 μg/mL for ROS by UPLC and HPLC techniques, respectively. 相似文献
50.
Polycation-sensitive membrane optodes based on the chromoionophore 2′,7′-dichlorofluorescein octadecylester (DCFOE) have previously been developed and used for determination of heparin via a titrimetric method. In this study, it is shown that some other important polyanions such as PPS (pentosan polysulfate), DNA, xanthan, Na-alginate, and carrageenan (food additive) can also be readily determined by using DCFOE-based microtiter plate-format optodes (MPOs) and polycationic titrants that bind these polyanionic species. The optical sensors are prepared with poly(vinyl chloride) (PVC), polyurethane (PU), bis(2-ethylhexyl)sebacate (DOS), and 2′,7′-dichlorofluorescein octadecylester (DCFOE) and exhibit reproducible and sensitive absorbance changes in response to the varying polycationic titrant concentrations. Three different polycations; protamine, poly-l-lysine and poly-l-arginine, are employed as titrants. The method has a detection limit of 1 μg mL−1, and a dynamic range of 1–40 μg mL−1. After the quantitative determinations are successfully demonstrated in buffered solutions, similar titrations are also performed in real samples. The method is validated by recovery studies in these samples. The average polyanion recoveries were quantitative [99.7(±1.3) % for pastry cream with vanillin (protamine titrant); 100.4 (±3.3) % for pastry gel with strawberry(PLA titrant), and 102.9(±2.0) % for pastry gel with strawberry (PLL titrant)]. 相似文献