全文获取类型
收费全文 | 166篇 |
免费 | 8篇 |
国内免费 | 22篇 |
专业分类
化学 | 129篇 |
晶体学 | 1篇 |
力学 | 16篇 |
综合类 | 1篇 |
数学 | 12篇 |
物理学 | 37篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 13篇 |
2012年 | 16篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 12篇 |
2005年 | 3篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1992年 | 10篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1982年 | 1篇 |
排序方式: 共有196条查询结果,搜索用时 250 毫秒
1.
基于校园网的实验管理系统的设计 总被引:2,自引:1,他引:1
主要讨论了应用实验室管理系统的必要性,并从用户需求分析、系统总体设计、功能模块的设计等方面对B/S实验室管理系统的开发进行了详细的阐述。 相似文献
2.
平朔气煤的煤岩显微组分结构研究 总被引:4,自引:3,他引:4
用显微光度计、扫描电子显微镜(SEM)、傅立叶变换红外光谱(FTIR)、X射线衍射光谱(XRD)和X光电子能谱(XPS)等测试手段研究了平朔气煤的等密度梯度离心分离(DGC)显微组分富集物的结构。结果表明,镜质组和稳定组结构相似,含氧基团基本相同,但丝质组结构则不同,它含有较多的羧基和羰基。根据实验结果讨论了三种显微组分的大分子结构,认为它们是由许多结构相似而又不相同的结构单元所构成。镜质组和稳定组的单元核心主要为脂环、缩聚芳环,环数为5—6个;丝质组单元核心主要为缩聚芳环,环数为7—8个,环缩合程度最高,芳香层片在空间排列规则,相互定向程度大。 相似文献
3.
IntroductionMethaneandcarbondioxidearetWomaincompositionsforthegreenhouseeffectandtheworldglobewanningll].ItisbeneficialtoourlivingenviroIUnenttocontrolthereleaseofthesetwogases.Theconversionofmethanetothecommonfeedstocksynthesisgas(carbonmonoxideandhydro… 相似文献
4.
有机锡聚合物兼具杀菌防腐的生物活性功能和一般高分子材料的结构功能,有着潜在的应用前景[1]。本工作应用X射线萤光光谱测定甲基丙烯酸三丁基锡(TBTM)和甲基丙烯酸异戊酯(IPMA)共聚物中锡的含量。方便,迅速地获得了该共聚物的组成,计算了TBTM和IPMA在四氢呋喃中,55℃下共聚合的竞聚率,其结果分别为0.29和0.24。 相似文献
5.
Capillary zone electrophoresis was used for characterising nine samples of natural organic matter (NOM) using phosphate buffer (25 mM, pH 7) and various modifiers; methanol (50 mM), acetonitrile (10%,v/v), dimethyl sulfoxide (5%,v/v), and urea (5 M). Principal component analysis (PCA) was used to examine whether the electrophoretic profiles can be utilised as fingerprints for tracing the NOM samples to their source and/or type of location. It was found that all modifiers except methanol affect the electropherograms. Furthermore, it was found that the PCA analysis carried out on the electrophoretic profiles recorded in buffer solution modified by urea gave the best results for fingerprinting. The distribution of the fingerprints suggests a model for the humic substances in which all samples can be regarded as mixtures between two endmembers: autochtonous and allocthoneous NOM. 相似文献
6.
7.
Seed‐Mediated Synthesis of Gold Tetrahedra in High Purity and with Tunable,Well‐Controlled Sizes 下载免费PDF全文
Yiqun Zheng Wenying Liu Tian Lv Ming Luo Dr. Hefei Hu Dr. Ping Lu Dr. Sang‐Il Choi Chao Zhang Dr. Jing Tao Prof. Yimei Zhu Prof. Zhi‐Yuan Li Prof. Younan Xia 《化学:亚洲杂志》2014,9(9):2635-2640
We report a facile synthesis of Au tetrahedra in high purity and with tunable, well‐controlled sizes via seed‐mediated growth. The success of this synthesis relies on the use of single‐crystal, spherical Au nanocrystals as the seeds and manipulation of the reaction kinetics to induce an unsymmetrical growth pattern for the seeds. In particular, the dropwise addition of a precursor solution with a syringe pump, assisted by cetyltrimethylammonium chloride and bromide at appropriate concentrations, was found to be critical to the formation of Au tetrahedra in high purity. Their sizes could be readily tuned in the range of 30–60 nm by simply varying the amount of precursor added to the reaction solution. The current strategy not only enables the synthesis of Au tetrahedra with tunable and controlled sizes but also provides a facile and versatile approach to reducing the symmetry of nanocrystals made of a face‐centered cubic lattice. 相似文献
8.
9.
Bioanalysis assays that reliably quantify biotherapeutics and biomarkers in biological samples play pivotal roles in drug discovery and development. Liquid chromatography coupled with mass spectrometry (LC–MS), owing to its superior specificity, faster method development and multiplex capability, has evolved as one of the most important platforms for bioanalysis of biotherapeutics, particularly new scaffolds such as half-life extension platforms for proteins and peptides, as well as antibody drug conjugates. Intact LC–MS analysis is orthogonal to bottom-up surrogate peptide approach by providing whole molecule quantitation and high-level sequence and structure information. Here we review the latest development in LC–MS bioanalysis of intact proteins and peptides by summarizing recent publications and discussing the important topics such as the comparison between top-down intact analysis and bottom-up surrogate peptide approach, as well as simultaneous quantitation and catabolite identification. Key bioanalytical issues around intact protein bioanalysis such as sensitivity, data processing strategies, specificity, sample preparation and LC condition are elaborated. For peptides, topics including quantitation of intact peptide vs. digested surrogate peptide, metabolites, sensitivity, LC condition, assay performance, internal standard and sample preparation are discussed. 相似文献
10.
Jincui Ye Wenying Yu Guosheng Chen Zhengrong Shen Su Zeng 《Biomedical chromatography : BMC》2010,24(8):799-807
The enantio‐separations of eight 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs (2‐APA NSAIDs) were established using reversed‐phase high‐performance liquid chromatography with hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP‐β‐CD and column temperature on retention and enantioselective separation were investigated. With 2‐APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP‐β‐CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC‐ODS (150 × 4.6 mm i.d., 5 μm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0–5.5, 20 mM) containing 25 mM HP‐β‐CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2‐APA NSAIDs in an enantioselective skin permeation study. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献