全文获取类型
收费全文 | 219篇 |
免费 | 9篇 |
国内免费 | 48篇 |
专业分类
化学 | 261篇 |
晶体学 | 2篇 |
力学 | 2篇 |
综合类 | 4篇 |
物理学 | 7篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 37篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 11篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
排序方式: 共有276条查询结果,搜索用时 31 毫秒
21.
A one-pot three-component approach for the synthesis of thiazol-2-imines has been described by the reaction of amine, phenyl isothiocyanate and β-nitroacrylate in [Hbim]BF4 ionic liquid. The method is applicable for aromatic, benzylic, aliphatic and cyclic amines. Reusable reaction media, regioselectivity, mild reaction condition, catalyst free and high yield of products are the salient features of this protocol. 相似文献
22.
Abstract Regioselective cleavage of 1,6-anhydro-maltose (1) with periodate and the subsequent recyclization with nitromethane gave 1,6-anhydro-3′-deoxy-3′-nitro-disaccharides (3). Three diastereomers, prepared by benzylidenation of 3, were separated by column chromatography. Each of 4′,6′-O-benzylidene derivatives successively underwent debenzylidenation, reduction of the nitro group, and peracetylation to give 3′-acetamido-3′-deoxy-disaccharide derivatives (7, 8, and 9). The configurations of the 3-amino sugar moietres in 7 (D-gluco), 8 (D-manno) and 9 (D-galacto) were determined on the basis of the 1H NMR data. The main product (7) was further modified to the 6-deoxy-6-nitro derivative. 相似文献
23.
24.
微流控芯片毛细管电泳激光诱导荧光检测法测定片剂中盐酸美西律的含量 总被引:1,自引:0,他引:1
建立了微流控芯片毛细管电泳激光诱导荧光检测法测定片剂中盐酸美西律含量的方法,对衍生条件和电泳条件进行了系统的考察。盐酸美西律经异硫氰酸荧光素(FITC)40℃衍生6h,以20 mmol/L硼砂为电泳缓冲溶液,进样30s后,分离电压2000V,可在1 min内完成一次检测。方法的检出限为0.022 mg/L、线性范围0.108~1.079 mg/L、相关系数0.994,加标回收率为99.7%~102.3%,方法适用于盐酸美西律的检测和质量控制。 相似文献
25.
异硫氰酸荧光素标记抗体的固体基质室温磷光性质研究 总被引:5,自引:0,他引:5
研究了异硫氰酸荧光素(FITC)标记的羊抗人抗体(GAHAb-FITC)和兔抗羊抗体9RAGAb-FITC),及其以三种免疫方式与人免疫球蛋白(IgG)反应所得免疫复合物在多种固体薄膜基质上发射室温磷光(RTP)的适宜条件及其光谱,强度和寿命等性质。研究发现,标记抗体及其免疫复合物保留了FITC优良的固体基质室温磷光性质,λ m0643em^(max)=525/650nm,其RTP强度与其浓度线性相关,并有很高的灵敏度,更为重要的是,免疫反应及其RTP检测能结合于同一基质,方便地相继完成,在聚酰胺膜(PM)上,以Pb(Ac)2为重原子微扰剂,稀释比为1:10(ψ)的GAHAb-FITC,RAGAb-FITC及其与人IgG形成的免疫复合物均能发射较强制 RTP信号并有较长的RTP寿命,本结果为建立相应的固体基质室温磷光免疫分析(SS-RTP-IA)新方法奠定了相应的实验基础。 相似文献
26.
Jason A. Kautz Donald F. Mullica J. Matt Farmer 《Journal of chemical crystallography》1999,29(6):729-733
The structural analysis of [(n-C4H9)4N]3[Y(NCS)6] (I) using single-crystal diffraction data and full-matrix least squares refinement has been carried out. The hexaisothiocyanate complex crystallizes in the centrosymmetric triclinic space group P
(No. 2) with unit cell constants of a = 12.431(1), b = 12.866(1), c = 22.750(2) Å, = 90.78(1), = 92.05(1), = 96.67(1)°, and Z = 2. The molecular unit consists of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoyttrate anionic group in which the six thiocyanate ligands are octahedrally coordinated through the N atom to the Y central ion. Selected bond distances and angles are presented as well as the synthesis and peripheral studies of (I). 相似文献
27.
28.
29.
30.
Guadalupe Silvero Martín ÁvalosReyes Babiano Pedro CintasJosé L. Jiménez Juan C. Palacios 《Tetrahedron》2011,67(40):7811-7820
Through a well-established enzymatic transformation glucosinolates release reactive isothiocyanates that can undergo further metabolic pathways affording a plethora of reactive metabolites. This study explores in detail the reaction of benzyl isothiocyanate, which possesses antitumor activity as alkylating agent, with d-glucosamine, commonly employed in oral treatments against osteoarthritis and inflammation. Structures of the resulting products and their evolution have been assessed and compared with those involving d-glucose, reported previously. Chemical results suggest that clinical treatments with d-glucosamine could reduce the beneficial effects associated with diets based on glucosinolate-rich foods. 相似文献