全文获取类型
收费全文 | 498篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
化学 | 431篇 |
晶体学 | 6篇 |
力学 | 4篇 |
数学 | 23篇 |
物理学 | 71篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 10篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 25篇 |
2013年 | 19篇 |
2012年 | 30篇 |
2011年 | 39篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 34篇 |
2007年 | 21篇 |
2006年 | 21篇 |
2005年 | 22篇 |
2004年 | 25篇 |
2003年 | 7篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1969年 | 3篇 |
1966年 | 2篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1947年 | 1篇 |
1910年 | 1篇 |
排序方式: 共有535条查询结果,搜索用时 15 毫秒
1.
Drah A. Tomić N. Z. Kovačević T. Djokić V. Tomić M. Heinemann R. J. Marinković A. 《Mechanics of Composite Materials》2020,56(2):249-260
Mechanics of Composite Materials - Commercial γ ? Al2O3 particles, Al2O3 n, and synthesized Al2O3 doped with iron oxide (Al2O3 Fe) were used as reinforcements to enhance the toughness of... 相似文献
2.
Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization 下载免费PDF全文
Dr. Bjorn Askevold Dr. Marat M. Khusniyarov Dr. Wolfgang Kroener Dr. Klaus Gieb Prof. Paul Müller Dr. Eberhardt Herdtweck Dr. Frank W. Heinemann Dr. Martin Diefenbach Prof. Max C. Holthausen Veacheslav Vieru Prof. Liviu F. Chibotaru Prof. Sven Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):579-589
Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH2CH2PtBu2)2}], [RuCl{N(CHCHPtBu2)(CH2CH2PtBu2)}], and [RuCl{N(CHCHPtBu2)2}], in which the ruthenium(II) ions are in the extremely rare square‐planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low‐lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non‐magnetic ground states arise for the two intermediate‐spin complexes owing to unusually large zero‐field splitting (D>+200 cm?1). The change in ground state electronic configuration is attributed to tailored pincer ligand‐to‐metal π‐donation within the PNP ligand series. 相似文献
3.
Eckhard Flter Till Wettlaufer Valentina Conty Maria Scharfe 《Molecules (Basel, Switzerland)》2021,26(6)
Oleogels or, more precisely, non-triglyceride structured lipid phases have been researched excessively in the last decade. Yet, no comprehensive knowledge base has emerged, allowing technology elevation from the laboratory bench into the industrial food application. That is partly due to insufficient characterization of the structuring systems studied. Examining a single composition decided upon by arbitrary methods does not stimulate progress in the research and technology area. A framework that gives much better guidance to product applications can easily be derived. For example, the incremental structure contribution concept is advocated as a parameter to compare the potency of structuring systems. These can straightforwardly be determined by combining solubility data and structural measurements in the recommended manner. The current method to determine the oil-binding capacity suffers from reproducibility and relevance. A newly developed method is suggested to overcome these shortcomings. The recommended new characterization of oleogels should contribute to a more comprehensive knowledge base necessary for product innovations. 相似文献
4.
Lars J. Wesenberg Erika Diehl Till J. B. Zähringer Carolin Dörr Dr. Dieter Schollmeyer Dr. Akihiro Shimizu Prof. Dr. Jun-ichi Yoshida Prof. Dr. Ute A. Hellmich Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17574-17580
The efficient production of many medicinally or synthetically important starting materials suffers from wasteful or toxic precursors for the synthesis. In particular, the aromatic non-protected primary amine function represents a versatile synthetic precursor, but its synthesis typically requires toxic oxidizing agents and transition metal catalysts. The twofold electrochemical amination of activated benzene derivatives via Zincke intermediates provides an alternative sustainable strategy for the formation of new C−N bonds of high synthetic value. As a proof of concept, we use our approach to generate a benzoxazinone scaffold that gained attention as a starting structure against castrate-resistant prostate cancer. Further improvement of the structure led to significantly increased cancer cell line toxicity. Thus, exploiting environmentally benign electrooxidation, we present a new versatile and powerful method based on direct C−H activation that is applicable for example the production of medicinally relevant compounds. 相似文献
5.
Nishit Goradia Christoph Wiedemann Dr. Christian Herbst Dr. Matthias Görlach Prof. Dr. Stefan H. Heinemann Dr. Oliver Ohlenschläger Dr. Ramadurai Ramachandran 《Chemphyschem》2015,16(4):739-746
An efficient approach to NMR assignments in intrinsically disordered proteins is presented, making use of the good dispersion of cross peaks observed in [15N,13C′]‐ and [13C′,1HN]‐correlation spectra. The method involves the simultaneous collection of {3D (H)NCO(CAN)H and 3D (HACA)CON(CA)HA} spectra for backbone assignments via sequential HN and Hα correlations and {3D (H)NCO(CACS)HS and 3D (HS)CS(CA)CO(N)H} spectra for side‐chain 1H and 13C assignments, employing sequential 1H data acquisitions with direct detection of both the amide and aliphatic protons. The efficacy of the approach for obtaining resonance assignments with complete backbone and side‐chain chemical shifts is demonstrated experimentally for the 61‐residue [13C,15N]‐labelled peptide of a voltage‐gated potassium channel protein of the Kv1.4 channel subunit. The general applicability of the approach for the characterisation of moderately sized globular proteins is also demonstrated. 相似文献
6.
Dr. Samuel F. Haysom Jonathan Machin Dr. James M. Whitehouse Dr. Jim E. Horne Dr. Katherine Fenn Dr. Yue Ma Dr. Hassane El Mkami Dr. Nils Böhringer Prof. Dr. Till F. Schäberle Prof. Dr. Neil A. Ranson Prof. Dr. Sheena E. Radford Prof. Dr. Christos Pliotas 《Angewandte Chemie (International ed. in English)》2023,62(34):e202218783
The β-barrel assembly machinery (BAM complex) is essential for outer membrane protein (OMP) folding in Gram-negative bacteria, and represents a promising antimicrobial target. Several conformational states of BAM have been reported, but all have been obtained under conditions which lack the unique features and complexity of the outer membrane (OM). Here, we use Pulsed Electron-Electron Double Resonance (PELDOR, or DEER) spectroscopy distance measurements to interrogate the conformational ensemble of the BAM complex in E. coli cells. We show that BAM adopts a broad ensemble of conformations in the OM, while in the presence of the antibiotic darobactin B (DAR-B), BAM′s conformational equilibrium shifts to a restricted ensemble consistent with the lateral closed state. Our in-cell PELDOR findings are supported by new cryoEM structures of BAM in the presence and absence of DAR-B. This work demonstrates the utility of PELDOR to map conformational changes in BAM within its native cellular environment. 相似文献
7.
8.
Matthias Krumb Dr. Maximilian Jäger Alice Voss Loreen Immig Dr. Karin Peters Danuta Kowalczyk Prof. Dr. Albrecht Bufe Prof. Dr. Till Opatz Prof. Dr. Otto Holst Prof. Dr. Christian Vogel Dr. Marcus Peters 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):928-933
Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy-protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy-protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subsequently coupled to a carrier protein to form a neoglycoconjugate. The allergy-protective activity of arabinogalactan could be reproduced with the partial structure in subsequent in vivo experiments. This is the first example of a successful simplification of arabinogalactan with a single partial structure while retaining its allergy-preventive potential. 相似文献
9.
Structure Elucidation and Activity of Kolossin A,the D‐/L‐Pentadecapeptide Product of a Giant Nonribosomal Peptide Synthetase 下载免费PDF全文
Prof. Dr. Helge B. Bode Dr. Alexander O. Brachmann Dr. Kirtikumar B. Jadhav Dr. Lydia Seyfarth Dipl.‐Chem. Christina Dauth Dr. Sebastian W. Fuchs Dr. Marcel Kaiser Dr. Nick R. Waterfield Dipl.‐Phys. Holger Sack Prof. Dr. Stefan H. Heinemann Prof. Dr. Hans‐Dieter Arndt 《Angewandte Chemie (International ed. in English)》2015,54(35):10352-10355
The largest continuous bacterial nonribosomal peptide synthetase discovered so far is described. It consists of 15 consecutive modules arising from an uninterrupted, fully functional gene in the entomopathogenic bacterium Photorhabdus luminescens. The identification of its cryptic biosynthesis product was achieved by using a combination of genome analysis, promoter exchange, isotopic labeling experiments, and total synthesis of a focused collection of peptide candidates. Although it belongs to the growing class of D ‐/ L ‐peptide natural products, the encoded metabolite kolossin A was found to be largely devoid of antibiotic activity and is likely involved in interspecies communication. A stereoisomer of this peculiar natural product displayed high activity against Trypanosoma brucei rhodesiense, a recalcitrant parasite that causes the deadly disease African sleeping sickness. 相似文献
10.
Johannes C. B. Dietschreit Annika Wagner T. Anh Le Philipp Klein Prof. Dr. Hermann Schindelin Prof. Dr. Till Opatz Prof. Dr. Bernd Engels Prof. Dr. Ute A. Hellmich Prof. Dr. Christian Ochsenfeld 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12769-12773
The absence of fluorine from most biomolecules renders it an excellent probe for NMR spectroscopy to monitor inhibitor–protein interactions. However, predicting the binding mode of a fluorinated ligand from a chemical shift (or vice versa) has been challenging due to the high electron density of the fluorine atom. Nonetheless, reliable 19F chemical-shift predictions to deduce ligand-binding modes hold great potential for in silico drug design. Herein, we present a systematic QM/MM study to predict the 19F NMR chemical shifts of a covalently bound fluorinated inhibitor to the essential oxidoreductase tryparedoxin (Tpx) from African trypanosomes, the causative agent of African sleeping sickness. We include many protein–inhibitor conformations as well as monomeric and dimeric inhibitor–protein complexes, thus rendering it the largest computational study on chemical shifts of 19F nuclei in a biological context to date. Our predicted shifts agree well with those obtained experimentally and pave the way for future work in this area. 相似文献