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991.
Within this study microwave assisted syntheses of functionalized polystyrene (PS), via ATRP, and tetra-aniline (TANI) end-capped polymers are demonstrated. Compared to conventional heating, microwave irradiation process in pulsed mode shows the feasibility of conducting end-capped polymers synthesis with no degradation, strong acceleration of polymerization rate and coupling reaction, controlled size and chemical formulation. Conducting polymers with controlled architectures in terms of molecular size of both the insulating (PS) and the conducting (TANI) moieties show a conductivity above 10−1 S cm−1 when containing 2 wt% TANI while composites of PS and TANI exhibited a conductivity of ca 10−5 S cm−1 when containing more than 7 wt% TANI. 相似文献
992.
Abd-Elsalam K Bahkali AH Moslem M De Wit PJ Verreet JA 《International journal of molecular sciences》2011,12(1):682-693
Early detection of infection is very important for efficient management of Mycosphaerella graminicola leaf blotch. To monitor and quantify the occurrence of this fungus during the growing season, a diagnostic method based on real-time PCR was developed. Standard and real-time PCR assays were developed using SYBR Green chemistry to quantify M. graminicola in vitro or in wheat samples. Microsatellite dinucleotide specific-primers were designed based on microsatellite repeats of sequences present in the genome of M. graminicola. Specificity was checked by analyzing DNA of 55 M. graminicola isolates obtained from different geographical origins. The method appears to be highly specific for detecting M. graminicola; no fluorescent signals were observed from 14 other closely related taxa. Primer (CT) 7 G amplified a specific amplicon of 570 bp from all M. graminicola isolates. The primers did not amplify DNA extracted from 14 other fungal species. The approximate melting temperature (Tm) of the (CT) 7 G primer was 84.2 °C. The detection limit of the real-time PCR assay with the primer sets (CT) 7 G is 10 fg/25 μL, as compared to 10 pg/25 μL using conventional PCR technology. From symptomless leaves, a PCR fragment could be generated two days after inoculation. Both conventional and real-time PCR could successfully detect the fungus from artificially inoculated wheat leaves. However, real-time PCR appeared much more sensitive than conventional PCR. The developed quantitative real-time PCR method proved to be rapid, sensitive, specific, cost-effective and reliable for the identification and quantification of M. graminicola in wheat. 相似文献
993.
This study is related to the use of hydroxyl functional acrylic cross‐linked polymer microparticles (CPM, also named microgels) as a chain transfer agent in cationic photopolymerization of cycloaliphatic epoxy monomer. All CPM were based on butyl acrylate and were consequently rubbery at ambient temperature. The effect of the stabilizing acrylate monomer used during the CPM synthesis was evaluated with respect to the viscoelastic properties of the photopolymerized cationic‐type epoxy films. The viscoelastic properties were correlated to the photopolymerized film morphology observed by transmission electron microscopy. Two acrylate monomers used as stabilizing agents during CPM synthesis were compared: cardura acrylate (CA) and lauryl acrylate (LA). CA was a good stabilizer for CPM in epoxy monomer before photocure and the CPM were well dispersed into the network after reaction. In contrast, LA was a poor stabilizer resulting in large CPM aggregation. The blend of these two types of CPM led to intermediate morphology, probably because of the flocculation of the CPM stabilized with LA. Conversely, CPM synthesized with a blend of the two stabilizing acrylate monomers induced in epoxy matrix a specific bi‐continuous morphology and consequently unique viscoelastic properties.
994.
Isabelle Henry Jean‐Pierre Pascault Mohamed Taha Grard Vigier Jean‐Jacques Flat 《应用聚合物科学杂志》2002,83(2):225-233
Precursors of polyurethane acrylate based on hydroxy‐terminated polybutadiene (HTPB) soft segments, different diisocyanate and hydroxy ethyl acrylate (HEA) as hard units, were synthesized in bulk or in solution in methyl methacrylate. During precursor synthesis (in bulk), microphase separation was observed by small‐angle X‐ray scattering (SAXS). Diffusing particles are around 50 Å in size and are assumed to be assembling of hard segments. From these morphologies, it can be deduced that some isocyanate groups were trapped/or buried in hard domains. At a larger scale, around millimeters, hard segment crystallites were observed. Properties such as molar masses, melting and glass‐transition temperatures, and viscosities were correlated with precursor structure and morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 225–233, 2002 相似文献
995.
Youchao Wang Dr. Patrick S. Felder Dr. Pierre Mesdom Dr. Olivier Blacque Prof. Dr. Thomas L. Mindt Dr. Kevin Cariou Prof. Dr. Gilles Gasser 《Chembiochem : a European journal of chemical biology》2023,24(19):e202300467
The search for new metal-based photosensitizers (PSs) for anticancer photodynamic therapy (PDT) is a fast-developing field of research. Knowing that polymetallic complexes bear a high potential as PDT PSs, in this study, we aimed at combining the known photophysical properties of a rhenium(I) tricarbonyl complex and a ruthenium(II) polypyridyl complex to prepare a ruthenium-rhenium binuclear complex that could act as a PS for anticancer PDT. Herein, we present the synthesis and characterization of such a system and discuss its stability in aqueous solution. In addition, one of our complexes prepared, which localized in mitochondria, was found to have some degree of selectivity towards two types of cancerous cells: human lung carcinoma A549 and human colon colorectal adenocarcinoma HT29, with interesting photo-index (PI) values of 135.1 and 256.4, respectively, compared to noncancerous retinal pigment epithelium RPE1 cells (22.4). 相似文献
996.
Florian Calzavara Pierre Florian Franck Fayon Vincent Sarou-Kanian Théo Guérineau Sylvain Danto Younès Messaddeq Marc Dussauze Véronique Jubera Thierry Cardinal Evelyne Fargin 《Journal of the American Ceramic Society》2023,106(10):5754-5765
Gallium-rich heavy metal oxide glasses have become highly attractive optical materials since they exhibit a wide transparency window spanning from the ultraviolet ∼270 nm up to the mid-infrared (IR) region ∼6 μm making them promising for a future integration in optical fiber devices. Nonetheless, in most composition, surface crystallization is a key limiting factor for optical fiber drawing using the classical preform-to-fiber method. Herein, taking advantage of structural information from vibrational spectroscopies (Raman/IR) and 71Ga Solid-State Nuclear Magnetic Resonance, we describe the key role of lanthanum and yttrium rare—earth elements on the glass structure and their impact on the capability to draw those new glass compositions into optical fibers. This approach emphasizes that yttrium ions as compared with lanthanum ones favor the glass disorder, increasing significantly the fraction of GaO5 units with respect to GaO4. That, combined with thermal analysis and examination of the crystallization behaviors, highlights that Y2O3 prevents the glass devitrification during the glass shaping. The smaller yttrium radius is believed to be the key physical parameter preventing the precipitation of the BayGa5-yGey+1La3-yO14 (y = 0, 1, 2, 3) langasite-type crystal phase. This study remains particularly relevant and opens up the way for the development of highly robust power scaled fiber devices operating from the visible up to the challenging mid-IR domain. 相似文献
997.
Nathalie Chapleau Pierre J. Carreau Carmen Peleteiro Paul-Andr Lavoie Tariq M. Malik 《Polymer Engineering and Science》1992,32(24):1876-1885
Thermal, rheological, morphological, and mechanical properties of a thermotropic liquid crystalline polymer, TLCP (copolyester Vectra A-950 from Hoechst), blended with a polycarbonate (PC), a polyethylene glycol terephthalate (PETG), and a blend of PC and PETG (20/80) are presented and discussed. Important supercooling effects are observed for the TLCP. For the blends the glass transition temperature of the matrix is shown to decrease slightly, suggesting partial miscibility of the components. A finer dispersion is observed for the TLCP/PC blends, at least for TLCP concentrations lower than 20%, for which the mechanical properties are quite good. For higher TLCP concentrations, as well as for the other two matrices, the mechanical properties follow more or less the mixing rule, and the morphology of the blends suggests poor adhesion. We were unable to obtain fibrillar structures by extruding the blends through a capillary rheometer; in the TLCP/PC blends, the TLCP domains were too small, and for the other blends the extrudates had not enough melt strength. 相似文献
998.
In view of the previously reported changes in the fatty acid composition of maternal liver triacylglycerols in late pregnancy,
changes in the composition of maternal liver triacylglycerol species were assessed in rats fed a semipurified diet during
pregnancy. Between day 18 and day 21 of pregnancy, total maternal liver triacylglycerols increased by 50%. Triacylglycerol
species with a total acyl carbon number (C) of 50 or 60 (C50, C60) remained unchanged while C48 and C52–C58 were relatively
increased. The individual triacylglycerol species containing one, two or three linoleoyl moieties were incompletely recovered
using a polar high temperature gas-liquid chromatography (GLC) column. Nevertheless, at day 21 compared to day 18, the linoleoyl-containing
species were relatively increased by 62–463%, while tripalmitin was decreased by 38%. Our data suggest that despite an adequate
intake of linoleic acid (25 g/kg in the diet), maternal hepatic triacylglycerol content of linoleic acid decreased during
mid-pregnancy but increased significantly toward term possibly in preparation for the transfer of linoleic acid to the neonate
during lactation. 相似文献
999.
Joseph Kreit Gérard Lefebvre Abdelhak Elhichami Pierre Germain Mohamed Saghi 《Lipids》1992,27(6):458-465
Cholesterol oxidase (cholesterol:oxygen oxidoreductase, EC 1.1.3.6) catalyzes the conversion of sterol Δ5-3β-alcohol to the corresponding Δ4-3-ketone with the reduction of oxygen to hydrogen peroxide.Rhodococcus species GK 1, a soil isolated microbe, produces an extracellular and a membrane-bound cholesterol oxidase; the latter is
bound to the outer surface of the microbial cell membrane. A simple and sensitive assay is described to measure the two enzyme
types; no enzyme extraction is needed for measuring the membrane-bound cholesterol oxidase. In this assay, hydrogen peroxide
is reduced by the chromogen 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in the presence of horseradish peroxidase, and the increased absorbance is followed
continuously at 600 nm (εm = 1.82×104 M−1·cm−1 at pH 7.0 and 30°C). The standardized assay medium contained 46.9 mM sodium-potassium phosphate buffer pH 7.0, 0.16% Triton
X-100, 312.5 μM ABTS, 50 μg peroxidase (12.5 units at 25°C), 6.25% isopropanol, 306.3 μM cholesterol or other sterols (kept
in solution with isopropanol), and cholesterol oxidase. Oxidation of one molecule of cholesterol by cholesterol oxidase gives
one molecule of hydrogen peroxide which reacts with two molecules of ABTS. The method is reproducible and the results correlate
well with those obtained by measuring the absorbance of Δ4-cholest-3-one at 240 nm (εm = 1.40×104 M−1·cm−1 at pH 7.0 and 30°C) and by the method of Allainet al. (Clin. Chem. 20, 470–475, 1974). In terms of efficiency, simplicity, and time saved, this coupled assay is expected to be a useful method
for monitoring microbial production of cholesterol oxidase on an industrial scale, and for determining cholesterol or other
sterols in biological fluids. 相似文献
1000.
M. RutnakornpitukM.S. Thompson L.A. HarrisK.E. Farmer A.R. EskerJ.S. Riffle J. ConnollyT.G. St. Pierre 《Polymer》2002,43(8):2337-2348
Stable suspensions of superparamagnetic cobalt nanoparticles have been prepared in poly(dimethysiloxane) (PDMS) carrier fluids in the presence of poly[dimethylsiloxane-b-(3-cyanopropyl)methylsiloxane-b-dimethylsiloxane] (PDMS-PCPMS-PDMS) triblock copolymers as steric stabilizers. A series of the polysiloxane triblock copolymers with systematically varied molecular weights were prepared via anionic polymerization using LiOH as an initiator. These copolymers formed micelles in toluene and served as ‘nanoreactors’ for thermal decomposition of the Co2(CO)8 precursor. The nitrile groups on the PCPMS central blocks are thought to adsorb onto the particle surface, while the PDMS endblocks protrude into the reaction medium to provide steric stability. The particle size can be controlled by adjusting the cobalt to copolymer ratio. TEM shows non-aggregated cobalt nanoparticles with narrow size distributions which are evenly surrounded with copolymer sheaths. However, some degree of surface oxidation was observed over time, resulting in a decrease in magnetic susceptibility. 相似文献