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541.
We have isolated flexible Sb2O3 nanoribbons and nanorods as the main product from the disintegration of nanoporous oxoselenoantimonates of the cetineite type, the size of the one-dimensional nanomaterials obtained ranging up to 15 microm in length with diameters between 8 and 50 nm. 相似文献
542.
The application of dendrimeric constructs in medical diagnostics and therapeutics is increasing. Dendrimers have attracted attention due to their compact, spherical three-dimensional structures with surfaces that can be modified by the attachment of various drugs, hydrophilic or hydrophobic groups, or reporter molecules. In the literature, many modified dendrimer systems with various applications have been reported, including drug and gene delivery systems, biosensors, bioimaging contrast agents, tissue engineering, and therapeutic agents. Dendrimers are used for the delivery of macromolecules, miRNAs, siRNAs, and many other various biomedical applications, and they are ideal carriers for bioactive molecules. In addition, the conjugation of dendrimers with antibodies, proteins, and peptides allows for the design of vaccines with highly specific and predictable properties, and the role of dendrimers as carrier systems for vaccine antigens is increasing. In this work, we will focus on a review of the use of dendrimers in cancer diagnostics and therapy. Dendrimer-based nanosystems for drug delivery are commonly based on polyamidoamine dendrimers (PAMAM) that can be modified with drugs and contrast agents. Moreover, dendrimers can be successfully used as conjugates that deliver several substances simultaneously. The potential to develop dendrimers with multifunctional abilities has served as an impetus for the design of new molecular platforms for medical diagnostics and therapeutics. 相似文献
543.
All the enantiomers of (1-amino-3-hydroxypropane-1,3-diyl)diphosphonic acid, newly design phosphonate analogues of 4-hydroxyglutamic acids, were obtained. The synthetic strategy involved Abramov reactions of diethyl (R)- and (S)-1-(N-Boc-amino)-3-oxopropylphosphonates with diethyl phosphite, separation of diastereoisomeric [1-(N-Boc-amino)-3-hydroxypropane-1,3-diyl]diphosphonates as O-protected esters, followed by their hydrolysis to the enantiomeric phosphonic acids. The absolute configuration of the enantiomeric phosphonates was established by comparing the 31P NMR chemical shifts of respective (S)-O-methylmandelic acid esters obtained from respective pairs of syn- and anti-[1-(N-Boc-amino)-3-hydroxypropane-1,3-diyl]diphosphonates according to the Spilling rule. 相似文献
544.
Jürgen Nelles Dorota Sendor Frank-Martin Petrat Ulrich Simon 《Journal of nanoparticle research》2010,12(4):1367-1375
The present study relates to the applicability of silicon nanoparticles as basic component in printing inks for the fabrication
of printable electronic devices. It is systematically investigated, how the surface functionalization of silicon nanoparticles
with 1-alkenes affects the electrical properties of thin films made of them. Therefore, films of as-prepared silicon nanoparticles
with a size of 42 nm as well as freshly etched ones, both terminated with hydrogen, are compared with films of silicon nanoparticles
functionalized with n-octene, n-dodecene, allylmercaptan, and allylamine, respectively. It is found, that the activation energy of the electron transport
through the films is in the range of 0.5 eV and scales with the polarity of the functionalization. 相似文献
545.
Iker Montes-Burgos Dorota Walczyk Patrick Hole Jonathan Smith Iseult Lynch Kenneth Dawson 《Journal of nanoparticle research》2010,12(1):47-53
Before commencing any nanotoxicological study, it is imperative to know the state of the nanoparticles to be used and in particular
their size and size distribution in the appropriate test media is particularly important. Particles satisfying standards can
be commercially purchased; however, these invariably cannot be used directly and need to be dispersed into the relevant biological
media. Often such changes in the environment or ionic strength, or a change in the particle concentration, results in some
aggregation or a shift in the particle size distribution. Such unexpected aggregation, dissolution or plating out, if unaccounted
for, can have a significant effect on the available nanoparticle dose and on interpretation of any results obtained thereafter.
Here, we demonstrate the application of characterisation instrumentation that sizes nanoparticles based on their Brownian
motion in suspension. Unlike classical light-scattering techniques, the nanoparticle tracking and analysis (NTA) technique
allows nanoparticles to be sized in suspension on a particle-by-particle basis allowing higher resolution and therefore better understanding of aggregation than ensemble methods (such as dynamic
light scattering (DLS) and differential centrifugation sedimentation (DCS)). Results will be presented from gold (standard)
nanoparticles in biologically relevant media that emphasise the importance of characterisation of the nanoparticle dispersion.
It will be shown how the NTA technique can be extended to multi-parameter analysis, allowing for characterization of particle
size and light scattering intensity on an individual basis. This multi-parameter measurement capability allows sub-populations
of nanoparticles with varying characteristics to be resolved in a complex mixture. Changes in one or more of such properties
can be followed both in real time and in situ. 相似文献
546.
The aim of this work was to determine phenolic acid and flavonoid contents, as well as antioxidant properties of propolis from different regions of Poland. Total phenolic content of propolis samples ranged from 150.05 to 197.14 mg/g GAE, while total flavonoid content was 35.64–62.04 mg/g QE. The dominant phenolic acid was p-coumaric acid, the content of which was from 37.54 to 116.95 mg/g. The samples also contained much ferulic acid. Among the flavonoids, chrysine and galangine were dominant, and for two samples, naringine was dominant. The propolis samples exhibited various antiradical activity measured towards DPPH√ (1.92–2.69 mM TE/g) and ABTS√+ (3.96–4.98 mM TE/g) and reducing power was determined by the ferric reducing antioxidant power method (6.23–9.19 mM Fe(II)/g). The significant linear correlations between total phenolic content and antiradical activity and between total phenolic content and reducing power were observed. Moreover, the total flavonoids content significantly correlated with antiradical activity and reducing power. 相似文献
547.
Rozkiewicz DI Brugman W Kerkhoven RM Ravoo BJ Reinhoudt DN 《Journal of the American Chemical Society》2007,129(37):11593-11599
This paper describes a new method to replicate DNA and RNA microarrays. The technique, which facilitates positioning of DNA and RNA with submicron edge resolution by microcontact printing (muCP), is based on the modification of poly(dimethylsiloxane) (PDMS) stamps with dendrimers ("dendri-stamps"). The modification of PDMS stamps with generation 5 poly(propylene imine) dendrimers (G5-PPI) gives a high density of positive charge on the stamp surface that can attract negatively charged oligonucleotides in a "layer-by-layer" arrangement. DNA as well as RNA is transfer printed from the stamp to a target surface. Imine chemistry is applied to immobilize amino-modified DNA and RNA molecules to an aldehyde-terminated substrate. The labile imine bond is reduced to a stable secondary amine bond, forming a robust connection between the polynucleotide strand and the solid support. Microcontact printed oligonucleotides are distributed homogeneously within the patterned area and available for hybridization. By using a robotic spotting system, an array of hundreds of oligonucleotide spots is deposited on the surface of a flat, dendrimer-modified stamp that is subsequently used for repeated replication of the entire microarray by microcontact printing. The printed microarrays are characterized by homogeneous probe density and regular spot morphology. 相似文献
548.
Lazewska D Maludziński P Szymańska E Kieć-Kononowicz K 《Biomedical chromatography : BMC》2007,21(3):291-298
The lipophilicity of antituberculotic 5-arylidene derivatives of (thio)hydantoin, thioacetazone and isoniazid has been determined by reversed-phase thin-layer chromatography (RP-TLC). Mixtures of acetone and water (with acetone content 60-85%) were used as the mobile phase. The R(M) (relative lipophilicity) of each compound (except isoniazid) decreased linearly with the increasing concentration of acetone. The partition coefficients (log P) of the compounds were calculated by the use of eight computer programs (ClogP, KowWin, XlogP, AlogPs, CAChe, Pallas, Interactive analysis and Slipper) and compared with the experimental lipophilicity (R(M0)). According to the observations the best tools for in silico predicting log P of (2-thio)hydantoins are programs KowWin and AlogPs. 相似文献
549.
Dorota Gabor Wojciech Kryszewski 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(18):6911-6932
The Alexander-type invariant for the bifurcation problems involving perturbations of linear Fredholm operators of nonnegative index is discussed and compared with another homotopy invariant (called the bifurcation index) detecting global bifurcations of solutions to multiparameter equations. 相似文献
550.
Sajewicz M Dolnik M Kronenbach D Gontarska M Kowalska T Epstein IR 《The journal of physical chemistry. A》2011,115(50):14331-14339
We employ high-performance liquid chromatography with diode array, evaporative light scattering, and mass spectrometric detection to monitor the oligomerization of L-lactic acid in pure acetonitrile and in 70% aqueous ethanol. The production of higher oligomers appears to proceed in an oscillatory fashion. A model is presented that involves the formation of aggregates (micelles), which catalyze the oligomerization. 相似文献