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101.
The time evolution of a slab of charged nuclear matter is studied within the TDHF method as a function of the initial conditions. The effective interaction is of Skyrme type plus a repulsive Yukawa interaction representing the Coulomb repulsion. The implications on the time evolution of specific collective as well as intrinsic excitations are investigated. Fission is found to occur at large enough excitation energies for a variety of initial conditions after timest fi ≈(1–3)·10?21 s. The final disintegration of the slab (“snatching”) is characterized by arapid rise of a potential barrier between the nascent fragments, the rise occurring int sn≈0.2·10?21 s. The importance for the fission process of the reflection symmetry of the occupied single particle states is demonstrated. 相似文献
102.
Sn-MCM-41--a heterogeneous selective catalyst for the Baeyer-Villiger oxidation with hydrogen peroxide 总被引:1,自引:0,他引:1
Corma A Navarro MT Nemeth L Renz M 《Chemical communications (Cambridge, England)》2001,(21):2190-2191
A new heterogeneous catalyst, Sn-MCM-41, is described for the Baeyer-Villiger reaction with hydrogen peroxide which selectively activates the carbonyl function for the nucleophilic attack by the oxidant, with high chemoselectivities when double bonds are present in the molecule. 相似文献
103.
Andrei Hutanu David Boelsterli Claudio Schmidli Cristina Montealegre Mike H. N. Dang Thai Balazs Bobaly Marius Koch Maria A. Schwarz 《Electrophoresis》2022,43(9-10):1107-1117
With recent FDA approval of two recombinant adeno-associated virus (rAAV)-based gene therapies, these vectors have proven that they are suitable to address monogenic diseases. However, rAAVs are relatively new modalities, and their production and therapy costs significantly exceed those of conventional biologics. Thus, significant efforts are made to improve the processes, methods, and techniques used in manufacturing and quality control (QC). Here, we evaluate transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), and two modes of capillary electrophoresis (CE) for their ability to analyze the DNA encapsidated by rAAVs. While TEM and AUC are well-established methods for rAAV, capillary gel electrophoresis (CGE) has been just recently proposed for viral genome sizing. The data presented reflect that samples are very complex, with various DNA species incorporated in the virus, including small fragments as well as DNA that is larger than the targeted transgene. CGE provides a good insight in the filling of rAAVs, but the workflow is tedious and the method is not applicable for the determination of DNA titer, since a procedure for the absolute quantification (e.g., calibration) is not yet established. For estimating the genome titer, we propose a simplified capillary zone electrophoresis approach with minimal sample preparation and short separation times (<5 min/run). Our data show the benefits of using the four techniques combined, since each of them alone is prone to delivering ambiguous results. For this reason, a clear view of the rAAV interior can only be provided by using several analytical methods simultaneously. 相似文献
104.
Endre A. Balazs 《Structural chemistry》2009,20(2):229-232
Separate terms to distinguish the matrix between the cells that grow in vitro and the matrix that separates and surrounds
cells in the living body are being proposed. The currently used designations: pericellular, extracellular, or intercellular
matrix should be used only for the substance produced by cells in vitro (cultures). The well organized, highly specific, and
stable structure with significant topographic variations between the cells of living tissues and organs should be called biological
matrix or briefly as biomatrix. My experiments published in the early 1940s on plant cell walls illustrate some similarities
between biomatrix of animal tissues and plant cell wall. When cells of plant epithelial membranes undergo plasmolysis, the
space between the contracting cell and cellulose cell wall is filled with filaments called Hechtian filaments or strands.
With silver impregnation, these filaments become a fibrous network, filling the space between the cell wall and the contracting
plasma (cell) membrane. A similar extracellular fibrous network has been described earlier after silver impregnation in some
animal tissues. I interpreted my finding that a pectin-like polysaccharide in the cell wall biomatrix and hyaluronan, the
only polysaccharide present in the biomatrix of animal tissues, are responsible for this fibrous network artifact. 相似文献
105.
Endre A. Balazs 《Structural chemistry》2009,20(2):341-349
Hyaluronan used today as a therapeutic agent in human and animal medicine must be in a highly purified form, free of immunologically
active protein molecules, from endotoxin and from inflammatory molecules originating from the tissues or bacterial cultures—the
source of hyaluronan. All hyaluronans, whether in liquid or in covalently crosslinked gel form, must have certain elastoviscous
properties to be usable for current therapeutic applications. Elastoviscous properties are especially important in the ophthalmic
viscosurgical use. The metabolism of hyaluronan is very fast in most tissues, except in the vitreus. The ability of injected
hyaluronan with a short half-life time in the joint to accomplish long-lasting analgesia represents a challenge for the design
of the various products. The history of the therapeutic use of hyaluronan and its present status is described, with emphasis
on its use in ophthalmic surgery and for a long-lasting analgesia in arthritic joints in humans and animals. The use of hyaluronan
gels is described in viscoaugmentation as injected into the dermal layer of the skin. Hyaluronan gels were also used as viscosupplements
injected into sphincter muscles to improve their function in aging or disease. The use of hyaluronan and its gel for drug
delivery was suggested several decades ago, and is also mentioned. 相似文献
106.
Attila Hunyadi Ana Martins Balazs Danko Da-Wei Chuang Patrick Trouillas Fang-Rong Chang Yang-Chang Wu George Falkay 《Tetrahedron letters》2013
Xanthine oxidase (XO) is a key enzyme in purine metabolism with an important role in various pathologies. Several flavonoids have been reported for their capacity to inhibit this enzyme, and, for these compounds, the ability to adopt a planar 3D structure has been accepted as fundamental prerequisite for such activity. Here we report the in vitro investigation of a series of non-planar protoflavone derivatives as XO inhibitors, among which protoapigenone 1′-O-propargyl ether was found to be an efficient competitive inhibitor of the enzyme with an IC50 value of 3.61 μM, significantly (p <0.001) stronger than the anti-gout drug allopurinol (IC50 = 8.72 μM). Methoxy substitution at C-7, however, resulted in complete loss of activity. In silico docking supported the observed structure–activity relationships, based on which a ‘planar structure’ itself can no longer be considered as a criterion for flavonoid-type inhibitors of XO. 相似文献
107.
Allen Chien Robert S. Maxwell Steve DeTeresa Lisa Thompson Rebecca Cohenour Bryan Balazs 《Journal of Polymer Science.Polymer Physics》2006,44(13):1898-1906
Crystallization in a series of variable crosslink density poly(dimethyl‐diphenyl)siloxanes random block copolymers reinforced through a mixture of precipitated and fumed silica fillers has been studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), nuclear magnetic resonance (NMR), and X‐ray diffraction (XRD). The silicone composite studied was composed of 94.6 mol % dimethoylsiloxane, 5.1 mol % diphenylsiloxane, and 0.3 mol % methyl‐vinyl siloxane (which formed crosslinking after peroxide cure). The polymer was filled with a mixture of 21.6 wt % fumed silica and 4.0 wt % precipitated silica previously treated with 6.8 wt % ethoxy‐end‐blocked siloxane processing aid. Molecular weight between crosslinks and filler–polymer interaction strength were modified by exposure to γ‐irradiation in either air or in vacuo. Isothermal DMA experiments illustrated that crystallization at ?85 °C occurred over a 1.8 hour period in silica‐filled systems and 2.2–2.6 hours in unfilled systems. The crystallization kinetics for irradiated samples were found to be dependent on crosslink density. Irradiation in vacuo resulted in faster overall crystallization rates compared to air irradiation for the same crosslink density, likely due to a reduction in the interaction between the polymer chains and the silica filler surface for samples irradiated in air. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1898–1906, 2006 相似文献
108.
109.
The peptide hormone hepcidin is a key homeostatic regulator of iron metabolism and involved in pathological regulation of iron in response to infection, inflammation, hypoxia, and anemia. It acts by binding to the iron exporter ferroportin, causing it to be internalized and degraded; however, little is known about the structure/activity relationships of the interaction of hepcidin with ferroportin. We show that there are key residues in the N-terminal region of hepcidin that influence its interaction with ferroportin, and we explore the structure/function relationships at these positions. A series of hepcidin mutants in which disulfide bonds were replaced with diselenide bonds showed no change in activity compared to native hepcidin. These results identify important constraints for the development of hepcidin congeners for the treatment of hereditary iron overload. 相似文献
110.
This paper describes a method for the fast identification and composition of disulfide-bonded peptides. A unique fragmentation signature of inter-disulfide-bonded peptides is detected using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF)/TOF mass spectrometry and high-energy collision-induced dissociation (CID). This fragmentation pattern identifies peptides with an interconnected disulfide bond and provides information regarding the composition of the peptides involved in the pairing. The distinctive signature produced using CID is a triplet of ions resulting from the cleavage of the disulfide bond to produce dehydroalanine, cysteine or thiocysteine product ions. This method is not applicable to intra-peptide disulfide bonds, as the cleavage mechanism is not the same and a triplet pattern is not observed. This method has been successfully applied to identifying disulfide-bonded peptides in a number of control digestions, as well as study samples where disulfide bond networks were postulated and/or unknown. 相似文献