全文获取类型
收费全文 | 618篇 |
免费 | 38篇 |
专业分类
化学 | 534篇 |
晶体学 | 5篇 |
力学 | 9篇 |
数学 | 42篇 |
物理学 | 66篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 10篇 |
2020年 | 20篇 |
2019年 | 20篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 22篇 |
2014年 | 16篇 |
2013年 | 45篇 |
2012年 | 34篇 |
2011年 | 61篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 50篇 |
2007年 | 34篇 |
2006年 | 29篇 |
2005年 | 52篇 |
2004年 | 36篇 |
2003年 | 35篇 |
2002年 | 35篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有656条查询结果,搜索用时 15 毫秒
521.
Anna A. M. Miller Dr. Phillip Biallas Benjamin D. A. Shennan Prof. Dr. Darren J. Dixon 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(2):e202314308
Herein we report the first enantioselective total synthesis of (+)-incargranine A, in nine steps. The total synthesis was enabled by an enantioselective intramolecular organocatalysed desymmetrising Michael addition of a malonamate ester to a linked dienone substrate that established pivotal stereocentres with excellent enantio- and complete diastereoselectivity. Furthermore, a key hemiaminal intermediate was accessed by developing an iridium-catalysed reductive cyclisation, and the scope of this transformation was explored to produce a range of bicyclic hemiaminal motifs. Once installed, the hemiaminal motif was used to initiate a biomimetic cascade to access the natural product directly in a single step. 相似文献
522.
Michael W. Mara Brian T. Phelan Zhu-Lin Xie Tae Wu Kim Darren J. Hsu Xiaolin Liu Andrew J. S. Valentine Pyosang Kim Xiaosong Li Shin-ichi Adachi Tetsuo Katayama Karen L. Mulfort Lin X. Chen 《Chemical science》2022,13(6):1715
In photosynthetic systems employing multiple transition metal centers, the properties of charge-transfer states are tuned by the coupling between metal centers. Here, we use ultrafast optical and X-ray spectroscopies to elucidate the effects of metal–metal interactions in a bimetallic tetrapyridophenazine-bridged Os(ii)/Cu(i) complex. Despite having an appropriate driving force for Os-to-Cu hole transfer in the Os(ii) moiety excited state, no such charge transfer was observed. However, excited-state coupling between the metal centers is present, evidenced by variations in the Os MLCT lifetime depending on the identity of the opposite metal center. This coupling results in concerted coherent vibrations appearing in the relaxation kinetics of the MLCT states for both Cu and Os centers. These vibrations are dominated by metal–ligand contraction at the Cu/Os centers, which are in-phase and linked through the conjugated bridging ligand. This study shows how vibronic coupling between transition metal centers affects the ultrafast dynamics in bridged, multi-metallic systems from the earliest times after photoexcitation to excited-state decay, presenting avenues for tuning charge-transfer states through judicious choice of metal/ligand groups.In photosynthetic systems employing multiple transition metal centers, the properties of charge-transfer states are tuned by the coupling between metal centers. 相似文献
523.
Sangeeth Pillai Akshaya Upadhyay Darren Sayson Bich Hong Nguyen Simon D. Tran 《Molecules (Basel, Switzerland)》2022,27(1)
In the past decade, wearable biosensors have radically changed our outlook on contemporary medical healthcare monitoring systems. These smart, multiplexed devices allow us to quantify dynamic biological signals in real time through highly sensitive, miniaturized sensing platforms, thereby decentralizing the concept of regular clinical check-ups and diagnosis towards more versatile, remote, and personalized healthcare monitoring. This paradigm shift in healthcare delivery can be attributed to the development of nanomaterials and improvements made to non-invasive biosignal detection systems alongside integrated approaches for multifaceted data acquisition and interpretation. The discovery of new biomarkers and the use of bioaffinity recognition elements like aptamers and peptide arrays combined with the use of newly developed, flexible, and conductive materials that interact with skin surfaces has led to the widespread application of biosensors in the biomedical field. This review focuses on the recent advances made in wearable technology for remote healthcare monitoring. It classifies their development and application in terms of electrochemical, mechanical, and optical modes of transduction and type of material used and discusses the shortcomings accompanying their large-scale fabrication and commercialization. A brief note on the most widely used materials and their improvements in wearable sensor development is outlined along with instructions for the future of medical wearables. 相似文献
524.
525.
A sensitive liquid chromatography–mass spectrometry bioanalytical assay for a novel anticancer candidate – ZMC1
下载免费PDF全文
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hongxia Lin Xin Yu Oliver S. Eng Brian Buckley Ah‐Ng Tony Kong Joseph R. Bertino Darren R. Carpizo Murugesan K. Gounder 《Biomedical chromatography : BMC》2015,29(11):1708-1714
ZMC1 {azetidinecarbothioic acid, [1‐(2‐pyridinyl) ethylidene] hydrazide} is a lead compound being developed as one of the first mutant p53 targeted anti‐cancer drugs. Establishing a precise quantitative method is an integral component of this development. The aim of this study was to develop a sensitive LC/MS/MS assay suitable for assessing purity, stability and preclinical pharmacokinetic studies of ZMC1. Acetonitrile protein precipitation extraction was chosen for plasma sample preparation with satisfactory recovery (84.2–92.8%) for ZMC1. Chromatographic separation was achieved on an Xterra C18 column (50 × 4.6 mm, 3.5 µm) using a gradient elution with mobile phase of 0.1% formic acid in water and acetonitrile. ZMC1 and internal standard 2‐amino‐6‐bromobenzothiazole were identified using selected‐ion monitoring mode at m/z 235.2/178.2 and m/z 231.0/150.0 at retention times of 5.2 and 6.3 min, respectively. The method was validated with a linearity range of 3.9–500.0 ng/mL in human plasma and showed acceptable reproducibility with intra‐ and interday precisions <5.9 and 10.5%, and accuracy within ±5.4% of nominal values. This analytical method together with basic stability data in plasma and plasma binding experiments provides a reliable protocol for the study of ZMC1 pharmacokinetics. This will greatly facilitate the pre‐clinical development of this novel anti‐cancer drug. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
526.
Ellen L. Heeley Darren J. Hughes Eleanor M. Crabb James Bowen Oier Bikondoa Beatriz Mayoral Tony McNally 《Journal of Polymer Science.Polymer Physics》2017,55(2):132-137
Here, the confirmation of an oriented nanohybrid shish‐kebab (NHSK) crystalline structure in a series of composites of poly(ethylene terephthalate) (PET) and multiwall carbon nanotubes (MWCNTs) is reported. The combined use of small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and thermal analysis has been used to investigate the morphology development in PET‐MWCNT nanocomposites under hot isothermal crystallization conditions. The MWCNTs act as both heterogeneous nucleating agents and surfaces (oriented shish structures) for the epitaxial growth of PET crystallites (kebabs) giving an oriented crystalline morphology. In contrast, the PET homopolymer does not show any residual oriented crystalline morphology during isothermal crystallization but gave a sporadic nucleation of a classic unoriented lamellar structure with slower crystallization kinetics. The results provide a valuable insight into the role of MWCNTs as nanoparticulate fillers in the morphology development and subsequent modification of physical properties in engineering polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 132–137 相似文献
527.
Dr. Rubén Manzano Dr. Swarup Datta Prof. Dr. Robert S. Paton Prof. Dr. Darren J. Dixon 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5928-5932
A silver(I) and amine co-catalyzed desymmetrization of 4-propargylamino cyclohexanones for the direct enantioselective synthesis of 2-azabicyclo[3.3.1]nonanes is described. Exploiting reactivity arising from dual activation of the pendant terminal alkyne by silver(I) and the ketone moiety through transient enamine formation, this synthetically relevant transformation is easy to perform, efficient and broad in scope. High enantioselectivity (up to 96 % ee) was achieved by exploiting a significant matching effect between the chirality of a cinchona alkaloid-derived aminophosphine ligand for the silver(I) salt and the 2-bis(aryl)methylpyrrolidine catalyst which was rationalized by DFT calculations. This allowed for the preparation of both enantiomers of the bicyclic product with near-identical stereocontrol. 相似文献
528.
Soap films at equilibrium are modeled, rather than as surfaces, as regions of small total volume through the introduction of a capillarity problem with a homotopic spanning condition. This point of view introduces a length scale in the classical Plateau's problem, which is in turn recovered in the vanishing volume limit. This approximation of area minimizing hypersurfaces leads to an energy based selection principle for Plateau's problem, points at physical features of soap films that are unaccessible by simply looking at minimal surfaces, and opens several challenging questions. © 2020 Wiley Periodicals LLC. 相似文献
529.
530.
Sudarat Yadnum Dr. Jérome Roche Eric Lebraud Philippe Négrier Patrick Garrigue Dr. Darren Bradshaw Dr. Chompunuch Warakulwit Prof. Jumras Limtrakul Prof. Alexander Kuhn 《Angewandte Chemie (International ed. in English)》2014,53(15):4001-4005
Herein, bipolar electrochemistry is applied in a straightforward way to the site‐selective in situ synthesis of metal–organic framework (MOF) structures, which have attracted tremendous interest in recent years because of their significant application potential, ranging from sensing to gas storage and catalysis. The novelty of the presented work is that the deposit can be intentionally confined to a defined area of a substrate without using masks or templates. The intrinsic site‐selectivity of bipolar electrochemistry makes it a method of choice to generate, in a highly controlled way, hybrid particles that may have different functionalities combined on the same particle. The wireless nature of electrodeposition allows the potential for mass production of such Janus‐type objects. 相似文献