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91.
Carina Brunecker Dr. Jonas H. Müssig Dr. Merle Arrowsmith Dr. Felipe Fantuzzi Andreas Stoy Dr. Julian Böhnke Dr. Alexander Hofmann Dr. Rüdiger Bertermann Prof. Dr. Bernd Engels Prof. Dr. Holger Braunschweig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(39):8518-8523
Diplatinum A-frame complexes with a bridging (di)boron unit in the apex position were synthesized in a single step by the double oxidative addition of dihalo(di)borane precursors at a bis(diphosphine)-bridged Pt02 complex. While structurally analogous to well-known μ-borylene complexes, in which delocalized dative three-center-two-electron M-B-M bonding prevails, theoretical investigations into the nature of Pt−B bonding in these A-frame complexes show them to be rare dimetalla(di)boranes displaying two electron-sharing Pt−B σ-bonds. This is experimentally reflected in the low kinetic stability of these compounds, which are prone to loss of the (di)boron bridgehead unit. 相似文献
92.
Jin Yu Manuel Schorlemer Alejandro Gomez Toledo Christian Pett Dr. Carina Sihlbom Prof. Göran Larson Dr. Ulrika Westerlind Dr. Jonas Nilsson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):1114-1124
Post‐translational glycosylation of proteins play key roles in cellular processes and the site‐specific characterisation of glycan structures is critical to understanding these events. Given the challenges regarding identification of glycan isomers, glycoproteomic studies generally rely on the assumption of conserved biosynthetic pathways. However, in a recent study, we found characteristically different HexNAc oxonium ion fragmentation patterns that depend on glycan structure. Such patterns could be used to distinguish between glycopeptide structural isomers. To acquire a mechanistic insight, deuterium‐labelled glycopeptides were prepared and analysed. We found that the HexNAc‐derived m/z 126 and 144 oxonium ions, differing in mass by H2O, had completely different structures and that high‐mannose N‐glycopeptides generated abundant Hex‐derived oxonium ions. We describe the oxonium ion decomposition mechanisms and the relative abundance of oxonium ions as a function of collision energy for a number of well‐defined glycan structures, which provide important information for future glycoproteomic studies. 相似文献
93.
Carina Van Zyl Bernard A. Prior James C. Du Preez 《Applied biochemistry and biotechnology》1988,17(1-3):357-369
The ability ofPichia stipitis to fermentd-xylose andd-glucose in the acid-hydrolyzed hemicellulose component of sugar cane bagasse depends on the alkali used to neutralize the hydrolyzate to pH 6.5. With NH4OH and NaOH no fermentation occurred, whereas neutralization with Ca(OH)2 gave the best results (Qpmax=0.25 g/L-h; Yp/s =0.38 g/g sugar). However, the volumetric productivity was still considerably less than observed in a semisynthetic medium with a sugar composition similar to the hydrolyzate. L-arabinose was not fermented but assimilated. Sequential neutralization methods failed to improve the fermentation. Acetic acid and lignin derivatives present in the hydrolyzate were major components that inhibited the fermentation. 相似文献
94.
This work describes a comprehensive study on the solid-phase synthesis of 3,4-disubstituted beta-lactams. In situ generated ketenes react with immobilized aldimines under mild conditions to generate libraries of beta-lactams in good to very good overall isolated yields. Different commercially available solid supports were studied, with the cost-effective Wang resin proving to be the most effective. The utility of the protocol was also demonstrated by the highly efficient asymmetric versions when homochiral ketenes or homochiral aldimines were used. A practical technique for the preparation of manual solid-phase parallel libraries of biologically interesting beta-lactam compounds, using Mukaiyama's salt as dehydrating agent, is also presented. Reactions were easily monitored by FT-IR and gel-phase 13C NMR using conventional equipment. 相似文献
95.
Débora de Oliveira Irajá do Nascimento Filho Marco di Luccio Carina Faccio Clarissa Dalla Rosa João Paulo Bender Nádia Lipke Cristiana Amroginski Cláudio Dariva José Vladimir de Oliveira 《Applied biochemistry and biotechnology》2005,121(1-3):231-241
This work investigated the production of fatty acid ethyl esters (FAEEs) from soybean oil using n-hexane as solvent and two commercial lipases as catalysts, Novozym 435 and Lipozyme IM. A Taguchi experimental design was
adopted considering the variables temperature (35–65°C), addition of water (0–10 wt/wt%), enzyme (5–20 wt/wt%) concentration,
and oil-to-ethanol molar ratio (1:3–1:10). It is shown that complete conversion in FAEE is achieved for some experimental
conditions. The effects of process variables on reaction conversion and kinetics of the enzymatic reactions are presented
for all experimental conditions investigated in the factorial design. 相似文献
96.
Carina M.L. Delpiccolo 《Tetrahedron letters》2004,45(21):4085-4088
An efficient and stereoselective procedure for a rapid access to diverse trans 3-alkyl β-lactams by solid-phase methodology is described. 相似文献
97.
Ulrike Wirth Julia Erl Saphia Azzam Dr. Carina Höring Dr. Michael Skiba Ritu Singh Kathrin Hochmuth PD Dr. Max Keller Prof. Dr. Joachim Wegener Prof. Dr. Burkhard König 《Angewandte Chemie (International ed. in English)》2023,62(21):e202215547
G protein-coupled cell surface receptors (GPCR) trigger complex intracellular signaling cascades upon agonist binding. Classic pharmacological assays provide information about binding affinities, activation or blockade at different stages of the signaling cascade, but real time dynamics and reversibility of these processes remain often disguised. We show that combining photochromic NPY receptor ligands, which can be toggled in their receptor activation ability by irradiation with light of different wavelengths, with whole cell label-free impedance assays allows observing the cell response to receptor activation and its reversibility over time. The concept demonstrated on NPY receptors may be well applicable to many other GPCRs providing a deeper insight into the time course of intracellular signaling processes. 相似文献
98.
Thaís Marcelino Miguel A. Ramos Docampo Xiaomin Qian Carina Ade Edit Brodszkij Marcel Ceccato Morten Foss Mark Dulchavsky James C. A. Bardwell Brigitte Städler 《Macromolecular bioscience》2023,23(8):2200528
The immobilization of enzymes on solid supports is an important challenge in biotechnology and biomedicine. In contrast to other methods, enzyme deposition in polymer brushes offers the benefit of high protein loading that preserves enzymatic activity in part due to the hydrated 3D environment that is available within the brush structure. The authors equipped planar and colloidal silica surfaces with poly(2-(diethylamino)ethyl methacrylate)-based brushes to immobilize Thermoplasma acidophilum histidine ammonia lyase, and analyzed the amount and activity of the immobilized enzyme. The poly(2-(diethylamino)ethyl methacrylate) brushes are attached to the solid silica supports either via a “grafting-to” or a “grafting-from” method. It is found that the grafting-from method results in higher amounts of deposited polymer and, consequently, higher amounts of Thermoplasma acidophilum histidine ammonia lyase. All polymer brush-modified surfaces show preserved catalytic activity of the deposited Thermoplasma acidophilum histidine ammonia lyase. However, immobilizing the enzyme in polymer brushes using the grafting-from method resulted in twice the enzymatic activity from the grafting-to approach, illustrating a successful enzyme deposition on a solid support. 相似文献
99.
Xiao Wang Dr. Ruojie Sha Dr. Martin Kristiansen Carina Hernandez Yudong Hao Prof. Chengde Mao Prof. James W. Canary Prof. Nadrian C. Seeman 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6545-6548
A 3D array of organic semiconductors was assembled using a DNA scaffold. An octameric aniline molecule (“octaniline”) was incorporated into a DNA building block based on a dimeric tensegrity triangle. The construct self-assembled to form a 3D crystal. Reversible redox conversion between the pernigraniline and leucoemeraldine states of the octaniline is retained in the crystal. Protonic doping gave emeraldine salt at pH 5, corresponding to the conductive form of polyaniline. Redox cycling within the crystal was visualized by color changes and Raman microscopy. The ease of conversion between the octaniline states suggests that it is a viable electronic switch within a unique 3D structure. 相似文献
100.