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排序方式: 共有257条查询结果,搜索用时 62 毫秒
81.
Xiangyu Teng Dr. Alena Sheveleva Dr. Floriana Tuna Prof. Keith R. Willison Dr. Liming Ying 《Chemphyschem》2021,22(23):2413-2419
The interaction between α-synuclein (αSyn) and Cu2+ has been suggested to be closely linked to brain copper homeostasis. Disruption of copper levels could induce misfolding and aggregation of αSyn, and thus contribute to the progression of Parkinson's disease (PD). Understanding the molecular mechanism of αSyn-Cu2+ interaction is important and controversies in Cu2+ coordination geometry with αSyn still exists. Herein, we find that the pathological H50Q mutation has no impact on the kinetics of Cu2+ binding to the high-affinity site of wild type αSyn (WT-αSyn), indicating the non-involvement of His50 in high-affinity Cu2+ binding to WT-αSyn. In contrast, the physiological N-terminally acetylated αSyn (NAc-αSyn) displays several orders of magnitude weaker Cu2+ binding affinity than WT-αSyn. Cu2+ coordination mode to NAc-αSyn has also been proposed based on EPR spectrum. In addition, we find that Cu2+ coordinated WT-αSyn is reduction-active in the presence of GSH, but essentially inactive towards ascorbate. Our work provides new insights into αSyn-Cu2+ interaction, which may help understand the multifaceted normal functions of αSyn as well as pathological consequences of αSyn aggregation. 相似文献
82.
Alena Haddley Poj Lertchoosakul Radhakrishnan Nair 《Periodica Mathematica Hungarica》2017,74(1):128-136
Let \(\kappa \) be an infinite cardinal, and \(2^\kappa <\lambda \le 2^{\kappa ^+}\). We prove that if there is a weak diamond on \(\kappa ^+\) then every \(\{C_\alpha :\alpha <\lambda \}\subseteq \mathcal {D}_{\kappa ^+}\) satisfies Galvin’s property. On the other hand, Galvin’s property is consistent with the failure of the weak diamond (and even with Martin’s axiom in the case of \(\aleph _1\)). We derive some consequences about weakly inaccessible cardinals. We also prove that the negation of a similar property follows from the proper forcing axiom. 相似文献
83.
Human serum albumin in electrospun PCL fibers: structure,release, and exposure on fiber surface 下载免费PDF全文
Vera S. Chernonosova Ren I. Kvon Alena O. Stepanova Yurii V. Larichev Andrey A. Karpenko Boris P. Chelobanov Elena V. Kiseleva Pavel P. Laktionov 《先进技术聚合物》2017,28(7):819-827
Human serum albumin (HSA) introduced to the fibers produced by electrospinning from HSA and polycaprolactone (PCL) solutions in hexafluoroisopropanol has been studied in terms of its structure, release from the fibers, stability of interaction with basic polymer, accessibility for protease attack, and cellular receptors, as well as dependence of the studied parameters on the protein concentration in fibers. A limited part of the protein leaves the fibers right after soaking with water, whereas the remaining protein stays tightly bound to fibers for a long time because protein nanoparticles are tightly integrated with PCL, as shown by small‐angle X‐ray scattering. As has been demonstrated, the proteins leave the fibers in complexes with PCL. X‐ray photoelectron spectroscopy demonstrates that the protein concentration on the fiber surface is higher than the concentration in electrospinning solution. The surface‐exposed protein is recognized by cell receptors and is partially hydrolyzed by proteinase K. The data on pulse protein release, presence of PCL in the protein released from matrixes, overrepresentation of the protein on the fiber surface, and tight interaction of protein with PCL may be useful for rational design of electrospun scaffolds intended for drug delivery and tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
84.
Day JG Iorenz M Wilding TA Friedl T Harding K Pröschold T Brennan D Müller J Santos LM Santos MF Osório HC Amaral R Lukesova A Hrouzek P Lukes M Elster J Lukavsky J Probert I Ryan MJ Benson EE 《Cryo letters》2007,28(5):359-376
Two cryopreservation methods, colligative cryoprotection coupled with controlled cooling and vitrification-based, encapsulation-dehydration were validated by five members of the EU research infrastructure consortium, COBRA, and two independent external validators. The test strain Chlorella vulgaris SAG 211-11b was successfully cryopreserved using two-step cooling employing passive (Mr Frosty) and Controlled Rate Freezers (CRF) attaining the desired recovery target within 15% of the median viability level (94%). Significant differences (p < 0.05) between cooling regimes were observed where Mr Frosty was more variable (Inter-Quartile Range being 21.5%, versus 13.0% for CRF samples). Viability assessment using fluorescein diacetate gave significantly (P < 0.0001) higher survival than growth in agar with median values being 96% and 89%, respectively. On employing encapsulation-dehydration, greater variability between some validators was observed, with six labs observing recovery in 100% of the beads (84-95% of cells surviving) and one lab observing survival in 80% of the treated beads. Bead disruption followed by algal growth in agar was considered the most reliable and accurate method of assessing cell survival for encapsulation-dehydration. 相似文献
85.
Synthesis of benzannulated N-heterocycles by a palladium-catalyzed C-C/C-N coupling of bromoalkylamines 总被引:1,自引:0,他引:1
A palladium-catalyzed domino intermolecular alkylation/intramolecular amination of functionalized aryl iodides represents a new strategy for the synthesis of benzannulated N-heterocycles, affording functionalized indolines and tetrahydroquinolines from simple precursors. 相似文献
86.
87.
Tomoya Wada Alena Sudholt Heinz Pitsch Norbert Peters 《Combustion Theory and Modelling》2013,17(5):906-936
The combustion chemistry of the first stage ignition and chemistry/flow interactions are studied for dimethyl ether (DME) with a mathematical analysis of two systems: a plug flow reactor study is used to reduce the reaction chemistry systematically. A skeletal reaction mechanism for the low temperature chemistry of DME until the onset of ignition is derived on the basis of the detailed DME mechanism of the Lawrence Livermore National Laboratory – see Curran, Fischer and Dryer, Int. J. Chem. Kinetics, Vol. 32 (2000). It is shown that reasonably good results for ignition delay times can be reached using a simple system of three ordinary differential equations and that the resulting analytical solution depends only on two reaction rates and the initial fuel concentration. The stepwise reduction of the system based on assumptions yields an understanding on why these reactions are so important. Furthermore, the validation of the assumptions yields insight into the influence of the fuel and the oxygen concentration on the temperature during the induction phase. To investigate the influence of chemistry/flow interactions, a 2D model with a laminar Hagen–Poiseuille flow and 2D-polynomial profiles for the radial species concentration is considered. For the 2D model, it is found that only the diffusion coefficients and the reactor radius need to be taken into consideration additionally to describe the system sufficiently. Also, the coupling of flow and chemistry is clarified in the mathematical analysis. The insight obtained from the comparison of the 2D model and the plug flow model is used to establish an average velocity for the conversion of ignition locations to ignition delay times in a laminar flow reactor. Finally, the 2D analytical solution is compared against new experimental data, obtained in such a laminar flow reactor for an undiluted DME/air mixture with an equivalence ratio of φ = 0.835 and a temperature range of 555 to 585 K at atmospheric pressure. 相似文献
88.
Eva Rosberg-Cody Alena Liavonchanka Cornelia Göbel R Paul Ross Orla O'Sullivan Gerald F Fitzgerald Ivo Feussner Catherine Stanton 《BMC biochemistry》2011,12(1):9
Background
The aim of this study was to determine the catalytic activity and physiological role of myosin-cross-reactive antigen (MCRA) from Bifidobacterium breve NCIMB 702258. MCRA from B. breve NCIMB 702258 was cloned, sequenced and expressed in heterologous hosts (Lactococcus and Corynebacterium) and the recombinant proteins assessed for enzymatic activity against fatty acid substrates. 相似文献89.
Stoikov II Yantemirova AA Nosov RV Rizvanov IKh Julmetov AR Klochkov VV Antipin IS Konovalov AI Zharov I 《Organic & biomolecular chemistry》2011,9(9):3225-3234
New p-tert-butyl thiacalix[4]arenes differently substituted at the lower rim with amide, hydroxyl and ester groups were synthesized. Binding properties of the compounds toward some tetrabutylammonium salts n-Bu(4)NX (X = F(-), Cl(-), Br(-), I(-), CH(3)CO(2)(-), H(2)PO(4)(-), NO(3)(-)) were studied by UV spectroscopy. It was found that the stoichiometry of the complexes, generally, is 1 : 1, and the association constants are in the range of 10(3)-10(5) M(-1). The p-tert-butyl thiacalix[4]arenes containing secondary amide groups trisubstituted at the lower rim bind the studied anions most effectively. Selective receptors for fluoride and dihydrogen phosphate salts of tetrabutylammonium were found. 相似文献
90.
Auxin and cytokinins have been identified as key regulators of plant development. Recently, these phytohormones have been shown to interact during important developmental processes, including positioning, identity acquisition and maintenance of meristem organizing centres, regulation of balance between cell division and differentiation, and postembryonic de novo organogenesis. Here, we discuss recent advances in our understanding of the underlying molecular mechanisms at the levels of regulating metabolism, signalling, gene expression and protein stability. 相似文献