全文获取类型
收费全文 | 1045篇 |
免费 | 46篇 |
国内免费 | 6篇 |
学科分类
数理化 | 1097篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 8篇 |
2017年 | 18篇 |
2016年 | 34篇 |
2015年 | 29篇 |
2014年 | 36篇 |
2013年 | 33篇 |
2012年 | 64篇 |
2011年 | 82篇 |
2010年 | 41篇 |
2009年 | 37篇 |
2008年 | 77篇 |
2007年 | 67篇 |
2006年 | 82篇 |
2005年 | 66篇 |
2004年 | 59篇 |
2003年 | 36篇 |
2002年 | 39篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 17篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1923年 | 1篇 |
排序方式: 共有1097条查询结果,搜索用时 78 毫秒
1.
2.
3.
4.
5.
6.
Dr. David Scheerer Prof. Dr. Heng Chi Dr. Dan McElheny Prof. Dr. Timothy A. Keiderling Prof. Dr. Karin Hauser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(16):3524-3534
Site-specific isotopic labeling of molecules is a widely used approach in IR spectroscopy to resolve local contributions to vibrational modes. The induced frequency shift of the corresponding IR band depends on the substituted masses, as well as on hydrogen bonding and vibrational coupling. The impact of these different factors was analyzed with a designed three-stranded β-sheet peptide and by use of selected 13C isotope substitutions at multiple positions in the peptide backbone. Single-strand labels give rise to isotopically shifted bands at different frequencies, depending on the specific sites; this demonstrates sensitivity to the local environment. Cross-strand double- and triple-labeled peptides exhibited two resolved bands that could be uniquely assigned to specific residues, the equilibrium IR spectra of which indicated only weak local-mode coupling. Temperature-jump IR laser spectroscopy was applied to monitor structural dynamics and revealed an impressive enhancement of the isotope sensitivity to both local positions and coupling between them, relative to that of equilibrium FTIR spectroscopy. Site-specific relaxation rates were altered upon the introduction of additional cross-strand isotopes. Likewise, the rates for the global β-sheet dynamics were affected in a manner dependent on the distinct relaxation behavior of the labeled oscillator. This study reveals that isotope labels provide not only local structural probes, but rather sense the dynamic complexity of the molecular environment. 相似文献
7.
8.
Mohammad Rostampour David J. Lawrence Jr Zaaferah Hamid Jade Darensbourg Percy Calvo-Marzal Karin Y. Chumbimuni-Torres 《Electroanalysis》2023,35(3):e202200121
It is well known that potentiometric sensors provide a versatile, cost-effective, and efficient platform for wearable applications. Unfortunately, mass production and commercialization of such devices is often constrained by the requirement of a calibration step, which is due to the poor sensor-to-sensor reproducibility and the need of conditioning the electrodes in the analyte before use. Herein, we fabricated calibration-free flexible sensors including ion-selective electrode and reference electrode by integrating single-walled carbon nanotubes (SWCNTs) with poly(3-octylthiophene) (POT) and applying on polyethylene terephthalate (PET) substrate. The developed sodium and potassium ion-selective electrodes (ISEs) display excellent repeatability, selectivity, stability as well as high sensor-to-sensor reproducibility, with a standard deviation of as low as 1.0 mV in artificial sweat microliter samples volume. 相似文献
9.
Dr. Karin Weidner Zhongdong Sun Dr. Naoya Kumagai Prof. Dr. Masakatsu Shibasaki 《Angewandte Chemie (International ed. in English)》2015,54(21):6236-6240
A direct aldol reaction of an α‐azido 7‐azaindolinylamide, promoted by a Cu‐based cooperative catalyst, is documented. Aromatic aldehydes bearing an ortho substituent exhibited diastereodivergency depending on the nature of the chiral ligands used. Smooth reactions with ynals highlighted the broad substrate scope. A vicinal azido alcohol unit in the product allowed direct access to the corresponding aziridine and facile hydrolysis of the 7‐azaindolinylamide moiety furnished enantioenriched β‐hydroxy‐α‐azido carboxylic acid derivatives. 相似文献
10.
Anneli Kruve Riin Rebane Karin Kipper Maarja-Liisa Oldekop Hanno Evard Koit Herodes Pekka Ravio Ivo Leito 《Analytica chimica acta》2015
This is the part I of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS) and discuss specific issues that arise with MS (and MS/MS) detection in LC (as opposed to the “conventional” detectors). The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to determine it, specifically in the case of LC–MS methods. 相似文献