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51.
This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed. 相似文献
52.
Increasingly stringent demands on the production of biopharmaceuticals demand monitoring of process parameters that impact on their quality. We developed an automated platform for on-line, near real-time monitoring of suspension cultures by integrating microfluidic components for cell counting and filtration with a high-resolution separation technique. This enabled the correlation of the growth of a human lymphocyte cell line with changes in the essential metabolic markers, glucose, glutamine, leucine/isoleucine and lactate, determined by Sequential Injection-Capillary Electrophoresis (SI-CE). Using 8.1 mL of media (41 μL per run), the metabolic status and cell density were recorded every 30 min over 4 days. The presented platform is flexible, simple and automated and allows for fast, robust and sensitive analysis with low sample consumption and high sample throughput. It is compatible with up- and out-scaling, and as such provides a promising new solution to meet the future demands in process monitoring in the biopharmaceutical industry. 相似文献
53.
Non-protected fluid room-temperature phosphorimetric procedure for the direct determination of naftopidil in biological fluids 总被引:1,自引:0,他引:1
J A Murillo Pulgarín A Ala?ón Molina M T Ala?ón Pardo 《Fresenius' Journal of Analytical Chemistry》2001,371(7):903-908
Non-protected fluid room temperature phosphorescence, NPRTP, has been applied to the determination of naftopidil in biological fluids. The proposed method is based on obtaining a phosphorescence signal from naftopidil using potassium iodide as heavy atom perturber and sodium sulfite as a deoxygenating reagent without a protected medium. Optimized conditions for the determination were 1.4 mol L= KI, 5.0 x l0(-3) mol L(-1) sodium sulfite, pH 6.5 (adjusted with sodium hydrogen phosphate-dihydrogen phosphate buffer solution, 5.0 x 10(-2) mol L(-1). The delay time, gate time, and time between flashes were 70 micros, 400 micros, and 5 ms, respectively. The maximum phosphorescence signal appeared instantly and the intensity was measured at lambda(ex)=287 nm and lambda(em)=525 nm. The response obtained was linearly dependent on concentration in the range 50 to 600 ng mL(-1). The detection limit, according to error-propagation theory, was 7.93 ng mL(-1) and the detection limit as proposed by Clayton was 11.12 ng mL(-1). The repeatability was studied by using ten solutions of 400 ng mL(-1) naftopidil; if the theory of error propagation is assumed the relative error is 0.88%. The standard deviation of replicates was found to be 3.5 ng mL(-1). This method was successfully applied to the analysis of naftopidil in human serum and urine with recoveries of 104.0 +/- 0.6% for serum and 106.0 +/- 1.0% for urine. 相似文献
54.
Kholoud M.M. Abou El-Nour Ala’a Eftaiha Abdulrhman Al-Warthan Reda A.A. Ammar 《Arabian Journal of Chemistry》2010,3(3):135-140
Over the past few decades, nanoparticles of noble metals such as silver exhibited significantly distinct physical, chemical and biological properties from their bulk counterparts. Nano-size particles of less than 100 nm in diameter are currently attracting increasing attention for the wide range of new applications in various fields of industry. Such powders can exhibit properties that differ substantially from those of bulk materials, as a result of small particle dimension, high surface area, quantum confinement and other effects. Most of the unique properties of nanoparticles require not only the particles to be of nano-sized, but also the particles be dispersed without agglomeration. Discoveries in the past decade have clearly demonstrated that the electromagnetic, optical and catalytic properties of silver nanoparticles are strongly influenced by shape, size and size distribution, which are often varied by varying the synthetic methods, reducing agents and stabilizers. Accordingly, this review presents different methods of preparation silver nanoparticles and application of these nanoparticles in different fields. 相似文献
55.
56.
Ala A. Alhusban Sokiyna Albustanji Lama A. Hamadneh Aliaa I. Shallan 《Molecules (Basel, Switzerland)》2021,26(16)
Breast cancer is one of the most prevalent cancers worldwide usually treated with Tamoxifen. Tamoxifen resistance development is the most challenging issue in an initially responsive breast tumor, and mechanisms of resistance are still under investigation. The objective of this study is to develop and validate a selective, sensitive, and simultaneous high performance liquid chromatography–tandem mass spectrometry method to explore the changes in substrates and metabolites in supernatant media of developed Tamoxifen resistance MCF-7 cells. We focus on the determination of lactate, pyruvate, and L-glutamine which enables the tracking of changes in metabolic pathways as a result of the resistance process. Chromatographic separation was achieved within 3.5 min. using a HILIC column (4.6 × 100 mm, 3.5 µm particle size) and mobile phase of 0.05 M acetic acid–ammonium acetate buffer solution pH 3.0: Acetonitrile (40:60 v/v). The linear range was 0.11–2.25, 0.012–0.227, and 0.02–0.20 mM for lactate, pyruvate, and L-glutamine, respectively. Within- and between-run accuracy was in the range 98.94-105.50% with precision (CV, %) of ≤0.86%. The results revealed a significant increase in both lactate and pyruvate production after acquiring the resistant. An increase in L-glutamine levels was also observed and could be attributed to its over production or decline in its consumption. Therefore, further tracking of genes responsible of lactate, pyruvate, and glutamine metabolic pathways should be performed in parallel to provide in-depth explanation of resistance mechanism. 相似文献
57.
58.
Carbaryl, a modern pesticide widely used for both agricultural and non-agricultural purposes, was determined from the chemiluminescence produced in its reaction with Ce(IV) in a nitric acid medium containing rhodamine 6G as sensitizer, using flow-injection techniques. A straightforward automatic method based on measurements peak height and peak area, which are directly proportional to the carbaryl concentration, was thus developed. Calibration graphs are linear over the concentration range from 50 to 2000 ng mL−1. The limit of detection, as determined according to Clayton, is 45.6 and 28.7 ng mL−1 for peak height and peak area measurements, respectively. The relative standard deviation for 10 samples was less than 1.4% with both types of measurements. Two commercial formulations containing carbaryl were analysed using both types of measurements, which provided acceptable recovery values. Solid-phase extraction was used to concentrate and separate the analyte from the matrix. The method was successfully applied to the analysis of spiked water samples as well as in soil and grain samples. The proposed method exhibited a high selectivity no other pesticide containing the naphthalene group such as antu, napropamide or naftalam, etc., was found to interfere with the determination of carbaryl. 相似文献
59.
Ala’a O. El-Ballouli Yadong Zhang Stephen Barlow Seth R. Marder Mohammad H. Al-Sayah Bilal R. Kaafarani 《Tetrahedron letters》2012,53(6):661-665
Binding studies of two sulfonamide-functionalized dibenzophenazine-based sensors are reported. Spectroscopic studies showed that both sensors are effective fluorescent turn-on sensors for several anions. Both sensors showed responses to acetate, benzoate, cyanide, and fluoride ions. NMR titrations confirmed the mode of binding of the sensors to be through H-bonding to the sulfonamide groups. 相似文献
60.
Maria Auxiliadora Fontes Prado Ricardo José Alves Alaíde Braga de Oliveira José Dias de Souza Filho 《合成通讯》2013,43(5):1015-1022
6-acetamido-6,8-dideox-1,2:3,4-di-O-isopropylidene- D -glycero-α-D-galacto-octopyranos-7-ulose (6), has been synthesised from D -galactose. The side chain elongation was carried out by cyano-amination of the protected dialdo sugar (2), followed by N-acetylation, and a subsequent Grignard reaction. 相似文献