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排序方式: 共有125条查询结果,搜索用时 140 毫秒
71.
介绍了水下目标激光探测高速数据采集系统设计的技术难点,设计了一种基于高速CMOS模/数转换芯片和高性能StratixⅡFPGA高速数据采集芯片的水下激光信号实时采集与传输系统,信号采集速率可达1GHz。系统的适用性及可靠性在水下目标激光探测试验中得到了验证。 相似文献
72.
Toribio L del Nozal MJ Bernal JL Bernal J Martín MT 《Journal of chromatography. A》2011,1218(30):4886-4891
Four chiral stationary phases, based on the phenylcarbamate derivatives of amylose or cellulose: Chiralcel OD-H, Chiralpak AD, Lux Cellulose-2 and Lux Amylose-2, were evaluated for the enantiomeric separation of an acetamide chiral intermediate, the (4S-trans)-4-(ethylamino)-4-(N-acetamide)-5,6-dihydro-(6S)-methyl-4H-thieno-[2,3-b]thiopyran-7,7-dioxide, using SFC. The effect of the different modifiers and temperatures, on the separation, was also studied. The chiral separation could not be achieved using the Chiralpak AD column, nevertheless the other columns provided excellent results with analysis times close to 6 min and resolutions higher than 2. The highest enantioresolutions and retentions were obtained with the Lux Cellulose-2 column and 2-propanol as organic modifier. The isoelution temperatures were estimated from the van't Hoff plots, and in all the cases they were above the temperature range studied which means that the enantiomeric separation was enthalpy driven. 相似文献
73.
G. Xu J.M. Hughes-Oliver J.D. Brooks J.L. Yeatts 《SAR and QSAR in environmental research》2013,24(2):135-156
Quantitative structure-activity relationship (QSAR) models are being used increasingly in skin permeation studies. The main idea of QSAR modelling is to quantify the relationship between biological activities and chemical properties, and thus to predict the activity of chemical solutes. As a key step, the selection of a representative and structurally diverse training set is critical to the prediction power of a QSAR model. Early QSAR models selected training sets in a subjective way and solutes in the training set were relatively homogenous. More recently, statistical methods such as D-optimal design or space-filling design have been applied but such methods are not always ideal. This paper describes a comprehensive procedure to select training sets from a large candidate set of 4534 solutes. A newly proposed ‘Baynes’ rule’, which is a modification of Lipinski's ‘rule of five’, was used to screen out solutes that were not qualified for the study. U-optimality was used as the selection criterion. A principal component analysis showed that the selected training set was representative of the chemical space. Gas chromatograph amenability was verified. A model built using the training set was shown to have greater predictive power than a model built using a previous dataset [1]. 相似文献
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在许多检测仪表的设计和应用中,由于被测信号幅度变化范围大、频带宽,通常采用设置量程变换开关的方式对被测信号进行满量程放大以保证测量的精度,使得硬件结构复杂。为了实现测量的智能化, 设计了一种基于FPGA(Field Programmable Gate Array,现场可编程门阵列)的智能放大器,可以根据信号的变化相应调整放大器的增益、可对动态范围宽的输入信号用最佳增益对其进行放大,使得放大后输出信号落入设定的窗口范围之内。该放大器已应用于植物种苗磁电场复合诱导繁育控制系统中,运行结果表明,该设计参数精度高,可靠性强,方便实用。 相似文献
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Stanislava G. Dmitrienko Elena V. KochukAuthor VitaeVladimir V. ApyariAuthor Vitae Veronika V. TolmachevaAuthor VitaeYury A. ZolotovAuthor Vitae 《Analytica chimica acta》2014
Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid–liquid and solid-phase extraction, dispersive liquid–liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed. 相似文献
79.
Anthony J. Veloso Paul M. Nagy Biao Zhang Devjani Dhar Anqi Liang Tarek Ibrahim Svetlana Mikhaylichenko Isabelle Aubert Kagan Kerman 《Analytica chimica acta》2013
The utility of a simple, low-cost detection platform for label-free electrochemical characterization of acetylcholinesterase (AChE) inhibition is demonstrated as a potential tool for screening of small-molecule therapeutic agents for Alzheimer's disease (AD). Technique validation was performed against the standard Ellman's colorimetric assay using the clinically established cholinesterase inhibitor (ChEI), Donepezil (Aricept®). Electrochemical measurements were obtained by differential pulse voltammetry (DPV) performed using a portable potentiostat system for detection of the enzymatic product, thiocholine (TCh), by direct oxidation on unmodified gold screen-printed electrodes. The IC50 profiles for Donepezil measured in vitro were found to be comparable between both colorimetric and electrochemical detection methods for the analysis of purified human erythrocyte-derived AChE (28 ± 7 nM by DPV; 26 ± 8 nM by Ellman's method). The selectivity of this unmodified electrode system was compared to a range of biological sulfur-containing compounds including cysteine, homocysteine, glutathione and methionine as well as ascorbic acid. Preliminary studies also demonstrated the potential applicability of this electrochemical technique for the analysis of Donepezil in crude cholinesterase samples from anterior cortex homogenates of C57BL/6J mice. 相似文献
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