全文获取类型
收费全文 | 3102篇 |
免费 | 54篇 |
国内免费 | 42篇 |
专业分类
化学 | 1720篇 |
晶体学 | 9篇 |
力学 | 112篇 |
数学 | 580篇 |
物理学 | 777篇 |
出版年
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 20篇 |
2016年 | 38篇 |
2015年 | 20篇 |
2014年 | 42篇 |
2013年 | 154篇 |
2012年 | 102篇 |
2011年 | 129篇 |
2010年 | 75篇 |
2009年 | 60篇 |
2008年 | 112篇 |
2007年 | 118篇 |
2006年 | 136篇 |
2005年 | 116篇 |
2004年 | 118篇 |
2003年 | 114篇 |
2002年 | 88篇 |
2001年 | 74篇 |
2000年 | 67篇 |
1999年 | 35篇 |
1998年 | 33篇 |
1997年 | 47篇 |
1996年 | 58篇 |
1995年 | 65篇 |
1994年 | 52篇 |
1993年 | 79篇 |
1992年 | 43篇 |
1991年 | 52篇 |
1990年 | 49篇 |
1989年 | 48篇 |
1988年 | 41篇 |
1987年 | 50篇 |
1986年 | 29篇 |
1985年 | 59篇 |
1984年 | 40篇 |
1983年 | 49篇 |
1982年 | 48篇 |
1981年 | 50篇 |
1980年 | 54篇 |
1979年 | 47篇 |
1978年 | 43篇 |
1977年 | 53篇 |
1976年 | 30篇 |
1975年 | 43篇 |
1974年 | 37篇 |
1973年 | 34篇 |
1972年 | 35篇 |
1971年 | 20篇 |
1966年 | 19篇 |
排序方式: 共有3198条查询结果,搜索用时 312 毫秒
1.
2.
3.
4.
5.
Prof. Margaret A. Brimble Dr. Pat J. Edwards Dr. Paul W. R. Harris Dr. Gillian E. Norris Dr. Mark L. Patchett Tom H. Wright Dr. Sung‐Hyun Yang Dr. Sarah E. Carley 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3556-3561
The first total synthesis of glycocin F, a uniquely diglycosylated antimicrobial peptide bearing a rare S‐linked N‐acetylglucosamine (GlcNAc) moiety in addition to an O‐linked GlcNAc, has been accomplished using a native chemical ligation strategy. The synthetic and naturally occurring peptides were compared by HPLC, mass spectrometry, NMR and CD spectroscopy, and their stability towards chymotrypsin digestion and antimicrobial activity were measured. This is the first comprehensive structural and functional comparison of a naturally occurring glycocin with an active synthetic analogue. 相似文献
6.
Reassessment of the NH4NO3 thermal decomposition technique for calibration of the N2O isotopic composition 下载免费PDF全文
7.
8.
Julie E. Bolding Alexander L. Nielsen Iben Jensen Tobias N. Hansen Line A. Ryberg Samuel T. Jameson Pernille Harris Günther H. J. Peters John M. Denu Joseph M. Rogers Christian A. Olsen 《Angewandte Chemie (International ed. in English)》2023,62(49):e202314597
The sirtuins are NAD+-dependent lysine deacylases, comprising seven isoforms (SIRT1–7) in humans, which are involved in the regulation of a plethora of biological processes, including gene expression and metabolism. The sirtuins share a common hydrolytic mechanism but display preferences for different ϵ-N-acyllysine substrates. SIRT7 deacetylates targets in nuclei and nucleoli but remains one of the lesser studied of the seven isoforms, in part due to a lack of chemical tools to specifically probe SIRT7 activity. Here we expressed SIRT7 and, using small-angle X-ray scattering, reveal SIRT7 to be a monomeric enzyme with a low degree of globular flexibility in solution. We developed a fluorogenic assay for investigation of the substrate preferences of SIRT7 and to evaluate compounds that modulate its activity. We report several mechanism-based SIRT7 inhibitors as well as de novo cyclic peptide inhibitors selected from mRNA-display library screening that exhibit selectivity for SIRT7 over other sirtuin isoforms, stabilize SIRT7 in cells, and cause an increase in the acetylation of H3 K18. 相似文献
9.
From the N‐Heterocyclic Carbene‐Catalyzed Conjugate Addition of Alcohols to the Controlled Polymerization of (Meth)acrylates 下载免费PDF全文
Winnie Nzahou Ottou Damien Bourichon Dr. Joan Vignolle Anne‐Laure Wirotius Dr. Fredéric Robert Prof. Yannick Landais Dr. Jean‐Marc Sotiropoulos Dr. Karinne Miqueu Prof. Daniel Taton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9447-9453
Among various N‐heterocyclic carbenes (NHCs) tested, only 1,3‐bis(tert‐butyl)imidazol‐2‐ylidene (NHCtBu) proved to selectively promote the catalytic conjugate addition of alcohols onto (meth)acrylate substrates. This rather rare example of NHC‐catalyzed 1,4‐addition of alcohols was investigated as a simple means to trigger the polymerization of both methyl methacrylate and methyl acrylate (MMA and MA, respectively). Well‐defined α‐alkoxy poly(methyl (meth)acrylate) (PM(M)A) chains, the molar masses of which could be controlled by the initial [(meth)acrylate]0/[ROH]0 molar ratio, were ultimately obtained in N,N‐dimethylformamide at 25 °C. A hydroxyl‐terminated poly(ethylene oxide) (PEO‐OH) macro‐initiator was also employed to directly access PEO‐b‐PMMA amphiphilic block copolymers. Investigations into the reaction mechanism by DFT calculations revealed the occurrence of two competitive concerted pathways, involving either the activation of the alcohol or that of the monomer by NHCtBu. 相似文献
10.
The Unexpected Influence of Precursor Conversion Rate in the Synthesis of III–V Quantum Dots 下载免费PDF全文
Daniel Franke Dr. Daniel K. Harris Lisi Xie Prof. Klavs F. Jensen Prof. Moungi G. Bawendi 《Angewandte Chemie (International ed. in English)》2015,54(48):14299-14303
Control of quantum dot (QD) precursor chemistry has been expected to help improve the size control and uniformity of III–V QDs such as indium phosphide and indium arsenide. Indeed, experimental results for other QD systems are consistent with the theoretical prediction that the rate of precursor conversion is an important factor controlling QD size and size distribution. We synthesized and characterized the reactivity of a variety of group‐V precursors in order to determine if precursor chemistry could be used to improve the quality of III–V QDs. Despite slowing down precursor conversion rate by multiple orders of magnitude, the less reactive precursors do not yield the expected increase in size and improvement in size distribution. This result disproves the widely accepted explanation for the shortcoming of current III–V QD syntheses and points to the need for a new generalizable theoretical picture for the mechanism of QD formation and growth. 相似文献