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Dr. Philippe Pierrat Dr. Gilles Laverny Dr. Gaëlle Creusat Dr. Patrick Wehrung Dr. Jean‐Marc Strub Dr. Alain VanDorsselaer Prof. Françoise Pons Dr. Guy Zuber Dr. Luc Lebeau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2344-2355
One of the potential benefits of drug delivery systems in medicine is the creation of nanoparticle‐based vectors that deliver a therapeutic cargo in sufficient quantity to a target site to enable a selective effect, width of the therapeutic window depending on the toxicity of the vector and the cargo. In this work, we intended to improve the siRNA delivery efficiency of a new kind of nucleic acid carrier, which is the result of the conjugation of the membrane phospholipid 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) to the membrane‐active species Triton X‐100 (TX100). We hypothesized that by improving the biodegradability the cytotoxicity of the conjugate might by reduced, whereas its original transfection potential would be tentatively preserved. DOPC was conjugated to Triton X‐100 through spacers displaying various resistance to chemical hydrolysis and enzyme degradation. The results obtained through in vitro siRNA delivery experiments showed that the initial phosphoester bond can be replaced with a phospho(alkyl)enecarbonate group with no loss in the transfection activity, whereas the associated cytotoxicity was significantly decreased, as assessed by metabolic activity and membrane integrity measurements. The toxicity of the conjugates incorporating a phospho(alkyl)enesuccinnate moiety proved even lower but was clearly balanced with a reduction of the siRNA delivery efficiency. Hydrolytic stability and intracellular degradation of the conjugates were investigated by NMR spectroscopy and mass spectrometry. A general trend was that the more readily degraded conjugates were those with the lower toxicity. Otherwise, the phospho(alkyl)enecarbonate conjugates revealed some hemolytic activity, whereas the parent phosphoester did not. The reason why these conjugates behave differently with respect to hemolysis might be a consequence of unusual fusogenic properties and probably reflects the difference in the stability of the conjugates in the intracellular environment. 相似文献
213.
Gaëtan R. P. Henry Xavier Drooghaag Dimitri D. J. Rousseaux Michel Sclavons Jacques Devaux Jacqueline Marchand‐Brynaert Véronique Carlier 《Journal of polymer science. Part A, Polymer chemistry》2008,46(9):2936-2947
This study reports a reactive extrusion process leading to very high levels of anhydride grafting (2.5–3 wt %) along polypropylene backbone without recovering grafted PP waxes at the die exit. Such high graftings are attainable without excessive degradation of the PP chain by using a brominated reagent. Simultaneously, this brominated reagent allows the tuning of the grafted PP crystallinity via epimerization of the PP backbone. Indeed, the synthesis of a mainly isotactic/atactic stereoblock polymer containing high levels of grafted succinic anhydride moieties is demonstrated by NMR and melting enthalpies recorded by DSC are definitely observed depressed and broadened. Grafting levels of around 3 wt % have been achieved and ascertained by both chemical titration and NMR spectroscopy. In addition, FTIR spectroscopy reveals an unusual observation: for the first time, only one single pair of symmetric and asymmetric carbonyl stretching bands are observed on those grafted PP, while, in other processes of anhydride grafting, those symmetric and asymmetric bands were both split in at least two bands. This suggests, for the here reported process, the absence of interacting grafted anhydride rings, i.e., absence of closely grafted anhydride moieties and absence of poly(maleic anhydride). All those observations support that this “bromine route” brings a really new grafting process for PP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2936–2947, 2008 相似文献
214.
Gaëtan R. P. Henry Xavier Drooghaag Mikhaël Vandeuren Michel Sclavons André Schanck Jacques Devaux Véronique Carlier Jacqueline Marchand‐Brynaert 《Journal of polymer science. Part A, Polymer chemistry》2009,47(18):4505-4518
Amorphous and low crystallinity polypropylenes were produced by reactive processing of commercial isotactic polypropylenes in the presence of a peroxide (2,5‐dimethyl‐2,5‐di(tert‐butylperoxy)hexane) and N‐bromosuccinimide. Characterization of the modified polypropylene microstructures using 13C NMR spectroscopy revealed that crystallinity loss is correlated with the epimerization of numerous methynes randomly along the polymer backbone, leading to decreasing isotacticities ([mmmm]) and average isotactic block lengths. Moreover, degradation usually induced by peroxide was shown to be comparatively limited in additional presence of N‐bromosuccinimide. This fast and easy process therefore allows the production of polypropylene plastomers and elastomers with controlled and homogeneous crystallinities and isotacticities, and relatively low molecular weight distributions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4505–4518, 2009 相似文献
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This paper describes the computation of fusion protons detection efficiency, which has been carried out by means of the known GOURDON code. For this purpose an analytical model of the tokamak magnetic field has been used. Computer simulations of different trajectories of charged particle, on the basis of the motion equations, have been performed with the GOURDON code. Detection efficiency, defined as the ratio of the number of detected particles to that of particles emitted from plasma, has been calculated. The transparency function of the detector system has been derived for given geometry of the ion-pinhole camera. Calculations have been carried out for the detector position used in recent experiments. The poloidal-and toroidal-symmetry of plasma and standard fusion-product source profile have been assumed. The computed detection efficiency is presented as a function of the main radius and particle pitch-angle for different spatial orientations of the detector head. 相似文献
217.
Jan Ga?uszka 《Discrete Mathematics》2008,308(24):6414-6425
Connections of some groupoid identities with the quasigroup and Latin square properties are investigated using combinatorial methods. 相似文献
218.
The aim of this paper is a study of the quasilinear transport equation, for instance the stationary heat equation. For periodically microheterogeneous media asymptotic homogenization has been performed with the local problem formulated as a minimization problem. The Golden–Papanicolaou integral representation theorem and some bounds developed for the linear equation have been extended. Two-point Padé approximants have been used to calculate bounds. Examples are also provided. 相似文献
219.
220.
The thermal decompositions of solid complexes of the type Ni(NCS)2L2 (L = pyridine,α-picoline,β-picoline, 2,6-lutidine, and quinoline) were studied by means of the derivatograph. It was found that the decompositions of complexes with pyridine,α-picoline, 2,6-lutidine, and quinoline (the pseudo-octahedral complex) are onestep processes, and those of complexes withβ-picoline and quinoline (the squareplanar complex) consist of two steps. Diffuse reflectance spectra were recorded to elucidate the structures of the decomposition intermediates. The reasons for the different stoichiometries of decomposition for complexes of the same type are discussed. 相似文献