全文获取类型
收费全文 | 1628篇 |
免费 | 177篇 |
国内免费 | 217篇 |
专业分类
化学 | 1862篇 |
晶体学 | 7篇 |
力学 | 2篇 |
综合类 | 6篇 |
数学 | 5篇 |
物理学 | 140篇 |
出版年
2024年 | 6篇 |
2023年 | 34篇 |
2022年 | 85篇 |
2021年 | 132篇 |
2020年 | 104篇 |
2019年 | 79篇 |
2018年 | 59篇 |
2017年 | 56篇 |
2016年 | 84篇 |
2015年 | 86篇 |
2014年 | 95篇 |
2013年 | 112篇 |
2012年 | 104篇 |
2011年 | 79篇 |
2010年 | 79篇 |
2009年 | 92篇 |
2008年 | 83篇 |
2007年 | 92篇 |
2006年 | 73篇 |
2005年 | 75篇 |
2004年 | 89篇 |
2003年 | 62篇 |
2002年 | 36篇 |
2001年 | 31篇 |
2000年 | 31篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 22篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2022条查询结果,搜索用时 656 毫秒
71.
ABSTRACTAmino acid derived macrocycles with elaborate well-defined stereochemistry are a unique class of compounds that have been isolated from natural sources. Macrocycles like cyclosporine, octreotide, and valinomycin have been used in multiple applications, like drugs or ion sensors. Chemists have long been fascinated by the unique molecular recognition capabilities of these macrocycles and tried to design synthetic analogs with similar functions. This article is focused on reviewing current research on amide and amino acid containing macrocycles that have been developed in research laboratories for biological recognition, specifically for anion sensing, ion transport, carbohydrate sensing, and peptide sensing. 相似文献
72.
73.
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
74.
《Mendeleev Communications》2020,30(1):25-27
- Download : Download high-res image (177KB)
- Download : Download full-size image
75.
76.
Christopher J. R. Illingworth Sree V. Chintipalli Stefano A. Serapian Andrew D. Miller Vaclav Veverka Mark D. Carr Christopher A. Reynolds 《Journal of computational chemistry》2012,33(16):1440-1447
Sense and antisense peptides, encoded by sense and corresponding antisense DNA strands, are capable of specific interactions that could be a driving force to mediate protein–protein or protein–peptide binding associations. The complementary residue hypothesis suggests that these interactions are founded upon the sum of pairwise interactions between amino acids encoded by corresponding sense and antisense codons. Despite many successful experimental results obtained with the hypothesis, however, the physicochemical basis for these interactions is poorly understood. We examined the potential of the hypothesis for general identification of protein–protein interaction sites, and the possible role of the hypothesis in determining folding in a broad set of protein structures. In addition, we performed a structural study to investigate the binding of a complementary peptide to IL‐1F2. Our results suggest that complementary residue pairs are no more frequent or conserved than average in protein–protein interfaces, and are statistically under‐represented amongst contacting residue pairs in folded protein structures. Although our structural results matched experimental observations of binding between the peptide and IL‐1F2, complementary residue interactions do not appear to be dominant in the bound structure. Overall, our data do not allow us to conclude that the complementary residue hypothesis accounts for specific sense–antisense peptide interactions. © 2012 Wiley Periodicals, Inc. 相似文献
77.
Synthesis and anticancer properties of RGD peptides conjugated to nitric oxide releasing functional groups and abiraterone 总被引:1,自引:0,他引:1
A series of analogues of the integrin binding aspartic acid-glycine-arginine (RGD) peptide sequence were synthesised conjugated to nitric oxide (NO) donating functional groups. Also the cytotoxicity of abiraterone, a prostate cancer drug, was explored when it was conjugated in three part constructs to RGD sequences and NO releasing heterocycles. In general the analogues showed integrin binding affinity comparable to RGD reference compounds, and all released NO by the Griess test assay. Two analogues exhibited significant cytotoxic effects against PC3 and MCF7 cell lines. 相似文献
78.
Nikita Brodyagin Aubrey L. Maryniak Ilze Kumpina John M. Talbott Dr. Martins Katkevics Prof. Dr. Eriks Rozners Prof. Dr. James A. MacKay 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4332-4335
Peptide nucleic acids (PNA) with extended isoorotamide containing nucleobases ( I o ) were designed for binding A–U base pairs in double-stranded RNA. Isothermal titration calorimetry and UV thermal melting experiments revealed improved affinity for A–U using the Io scaffold in PNA. PNAs having four sequential Io extended nucleobases maintained high binding affinity. 相似文献
79.
80.
The influences of fluorines in chemistry have emerged as a breakthrough in various arenas of bio-organic and medicinal chemistry. But its incorporation in β-turn design and its implications for supramolecular chemistry remains in a rudimentary stage. Inspired by the diversity displayed by the isomers of mono-fluorinated phenylalanine in biological sciences, here our effort is to modulate the solid state conformational analysis of three terminally protected synthetic tripeptides Boc-(Y)-F-Phe-Aib-Xaa-OMe, where (Y is (2)-F-Phe, Xaa; Leu in peptide I, (3)-F-Phe, Xaa; Leu in peptide II and (4)-F-Phe, Xaa; Ile in peptide III). Interestingly, all the three peptides display a conformational preference for β-turns, stabilized by 4→1 intramolecular hydrogen bonding. Our investigation further demonstrates that mere interchange of positions of fluorines in mono-fluorinated phenylalanine in peptides I–III introduces significant diversity in supramolecular chemistry. X-ray crystallography sheds some light at atomic resolution. Furthermore, this supramolecular heterogeneous behavior is evident from the morphologies obtained from the materials of all the three peptides grown from acetone to petroleum ether solution, studied by field emission scanning electron microscopy. Thus, these monofluorinated peptides I–III may serve as prominent candidates in understanding the structure and function of misfolded disease causing peptides like prion and Alzheimer's amyloid. 相似文献