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51.
Several studies have been carried out on the grinding characteristic of three species of common wheat (Triticum aestivum, ssp. vulgare). The three-day germinated kernels were pulverized in a micro hammer mill equipped with a changeable screen. The moisture of samples was 12% (w.b.). The results showed that the sprouting of wheat had a significant influence on the grinding process. The average particle size of the pulverized material obtained from the sprouted kernels was almost always significantly lower than those from the sound kernels. The highest changes were observed in the increase of the fraction of particles below a size of 200 μm, caused by sprouting. The sprouting caused a decrease in the value of specific grinding energy in all cultivars. Based on the parameters of screen openings and cultivar, the values of specific grinding energy ranged from 35.5 to 141.6 kJ kg−1 and from 41.4 to 164.3 kJ kg−1 for the sprouted and sound kernels, respectively. In addition, the other values of grinding energy indices confirmed that sprouting significantly reduced the grinding energy requirements. The average value of the grinding ability index was 3.9 and 4.8 kJ m−2 for the sprouted and sound wheat, respectively. Whereas, sprouting caused a decrease in the average value of the grinding index from 71.2 to 58.0 kJ kg−1 mm0.5.  相似文献   
52.
A simple and effective way to manufacture graphene from a coal tar pitch (CTP) is demonstrated. Silica (SiO2) nanoparticles were used to modify the CTP as carbon precursor. A silica nanofiller introduced into the CTP matrix underwent carboreduction during heat treatment to 2000 °C, resulting in the formation of silicon carbide. Surfaces of SiC grains were sites for graphene formation. The influence of SiO2 on the structure and microstructure of CTP- based carbon matrix, after annealing up to 2800 °C, was studied. Carbon samples were analyzed using X- ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Raman Spectroscopy. Crystallite sizes (La, Lc) and interplanar distance (d002) were determined. The presence of SiO2 in CTP carbon precursor favored the crystallites’ growth in the ‘a′ crystallographic graphite direction, and inhibited their growth on the ‘c′ axis. The crystallites composing of graphene layers, were characterized by an elongated dimension in the ‘a′ axis direction. Above 2000 °C silicon carbide decomposed, followed by the sublimation of silicon from the carbon matrix.  相似文献   
53.
Atherosclerosis involves an ongoing inflammatory response of the vascular endothelium and vessel wall of the aorta and vein. The pleiotropic effects of statins have been well described in many in vitro and in vivo studies, but these effects are difficult to achieve in clinical practice due to the low bioavailability of statins and their first-pass metabolism in the liver. The aim of this study was to test a vessel wall local drug delivery system (DDS) using PLA microstructures loaded with simvastatin. Wistar rats were fed high cholesterol chow as a model. The rat vessels were chemically injured by repeated injections of perivascular paclitaxel and 5-fluorouracil. The vessels were then cultured and treated by the injection of several concentrations of poly(L,L-lactide) microparticles loaded with the high local HMG-CoA inhibitor simvastatin (0.58 mg/kg) concentration (SVPLA). Histopathological examinations of the harvested vessels and vital organs after 24 h, 7 days and 4 weeks were performed. Microcirculation in mice as an additional test was performed to demonstrate the safety of this approach. A single dose of SVPLA microspheres with an average diameter of 6.4 μm and a drug concentration equal to 8.1% of particles limited the inflammatory reaction of the endothelium and vessel wall and had no influence on microcirculation in vivo or in vitro. A potent pleiotropic (anti-inflammatory) effect of simvastatin after local SVPLA administration was observed. Moreover, significant concentrations of free simvastatin were observed in the vessel wall (compared to the maximum serum level). In addition, it appeared that simvastatin, once locally administered as SVPLA particles, exerted potent pleiotropic effects on chemically injured vessels and presented anti-inflammatory action. Presumably, this effect was due to the high local concentrations of simvastatin. No local or systemic side effects were observed. This approach could be useful for local simvastatin DDSs when high, local drug concentrations are difficult to obtain, or systemic side effects are present.  相似文献   
54.
This study concerns green thermoplastic polyurethanes (TPU) obtained by controlling the chemical structure of flexible segments. Two types of bio-based polyether polyols—poly(trimethylene glycol)s—with average molecular weights ca. 1000 and 2700 Da were used (PO3G1000 and PO3G2700, respectively). TPUs were prepared via a two-step method. Hard segments consisted of 4,4′-diphenylmethane diisocyanates and the bio-based 1,4-butanodiol (used as a chain extender and used to control the [NCO]/[OH] molar ratio). The impacts of the structure of flexible segments, the amount of each type of prepolymer, and the [NCO]/[OH] molar ratio on the chemical structure and selected properties of the TPUs were verified. By regulating the number of flexible segments of a given type, different selected properties of TPU materials were obtained. Thermal analysis confirmed the high thermal stability of the prepared materials and revealed that TPUs based on a higher amount of prepolymer synthesized from PO3G2700 have a tendency for cold crystallization. An increase in the amount of PO3G1000 at the flexible segments caused an increase in the tensile strength and decrease in the elongation at break. Melt flow index results demonstrated that the increase in the amount of prepolymer based on PO3G1000 resulted in TPUs favorable in terms of machining.  相似文献   
55.
Physical exercise is known to influence hormonal mediators of appetite, but the effect of short-term maximal intensity exercise on plasma levels of appetite hormones and cytokines has been little studied. We investigated the effect of a 30 s Wingate Test, followed by a postprandial period, on appetite sensations, food intake, and appetite hormones. Twenty-six physically active young males rated their subjective feelings of hunger, prospective food consumption, and fatigue on visual analogue scales at baseline, after exercise was completed, and during the postprandial period. Blood samples were obtained for the measurement of nesfatin-1, ghrelin, leptin, insulin, pancreatic polypeptide (PP), human growth factor (hGH) and cytokine interleukin-6 (IL-6), irisin and plasma lactate concentrations, at 30 min before exercise, immediately (210 s) after exercise, and 30 min following a meal and at corresponding times in control sedentary males without ad libitum meal intake, respectively. Appetite perceptions and food intake were decreased in response to exercise. Plasma levels of irisin, IL-6, lactate, nesfatin-1 and ghrelin was increased after exercise and then it was returned to postprandial/control period in both groups. A significant rise in plasma insulin, hGH and PP levels after exercise was observed while meal intake potentiated this response. In conclusion, an acute short-term fatiguing exercise can transiently suppress hunger sensations and food intake in humans. We postulate that this physiological response involves exercise-induced alterations in plasma hormones and the release of myokines such as irisin and IL-6, and supports the notion of existence of the skeletal muscle–brain–gut axis. Nevertheless, the detailed relationship between acute exercise releasing myokines, appetite sensations and impairment of this axis leading to several diseases should be further examined.  相似文献   
56.
Arabidopsis thaliana possesses two acyl-CoA:lysophosphatidylethanolamine acyltransferases, LPEAT1 and LPEAT2, which are encoded by At1g80950 and At2g45670 genes, respectively. Both single lpeat2 mutant and double lpeat1 lpeat2 mutant plants exhibit a variety of conspicuous phenotypes, including dwarfed growth. Confocal microscopic analysis of tobacco suspension-cultured cells transiently transformed with green fluorescent protein-tagged versions of LPEAT1 or LPEAT2 revealed that LPEAT1 is localized to the endoplasmic reticulum (ER), whereas LPEAT2 is localized to both Golgi and late endosomes. Considering that the primary product of the reaction catalyzed by LPEATs is phosphatidylethanolamine, which is known to be covalently conjugated with autophagy-related protein ATG8 during a key step of the formation of autophagosomes, we investigated the requirements for LPEATs to engage in autophagic activity in Arabidopsis. Knocking out of either or both LPEAT genes led to enhanced accumulation of the autophagic adaptor protein NBR1 and decreased levels of both ATG8a mRNA and total ATG8 protein. Moreover, we detected significantly fewer membrane objects in the vacuoles of lpeat1 lpeat2 double mutant mesophyll cells than in vacuoles of control plants. However, contrary to what has been reported on autophagy deficient plants, the lpeat mutants displayed a prolonged life span compared to wild type, including delayed senescence.  相似文献   
57.
The cycloaddition of CO2 to epoxides represents a green efficient method to form bis(cyclic carbonate)s. The main purpose of the work reported in this paper was to examine the effect of the gas flow rate (20, 40, 60 and 100 mL min–1) during carbonation on the conversion yield, chemical structure, rheological behaviour and thermal properties of the prepared compounds. A series of new bis(cyclic carbonate)s was obtained from bio‐based polyether polyol. The syntheses were performed in the absence of toxic solvents and the process did not require the use of elevated pressure. The progressive structural changes and the presence of characteristic chemical groups were monitored by attenuated total reflection Fourier transform infrared spectroscopy. The characterization of the structure by 1H NMR and 13C NMR also confirmed the formation of cyclic carbonate moieties. The non‐Newtonian behaviour and the optimal mathematical model (Herschel–Bulkley) were verified by rheological measurements. The materials obtained could be used as a chemical intermediate to synthesize advanced materials based upon polyurethanes without using isocyanates. © 2019 Society of Chemical Industry  相似文献   
58.
In vivo, proteins are the main targets for radicals and other reactive species. Their reactions result in formation of amino acid radicals on the protein surface that often yield tryptophan and tyrosyl radicals or, in the presence of O2, protein peroxyl radicals and hydroperoxides. All these species may propagate damage to biomolecules. Low molecular weight antioxidants, such as ascorbate, urate, and glutathione, are part of the defense system and function by repairing damaged proteins. We briefly review the existing knowledge about protein and amino acid radicals and their repair by antioxidants, including results of our investigations. The main question addressed is whether the antioxidants ascorbate, urate, and glutathione are able to repair amino acid radicals in model compounds and in proteins in vitro by pulse radiolysis. We show that ascorbate and urate repair tryptophan and tyrosyl radicals efficiently and inhibit proton-coupled electron transfer from tyrosine residues to tryptophan radicals in a number of proteins. In contrast, repair by glutathione is much slower. Ascorbate also rapidly reduces the peroxyl radicals of the N-acetylamide derivatives of glycine, alanine, and proline, whereas glutathione reduces peroxyl radicals in lysozyme. In vivo urate, ascorbate, and glutathione may prevent biological damage or, at least, reduce its rate, because they: (a) repair tryptophan and tyrosyl radicals in proteins and (b) reduce protein peroxyl radicals to the corresponding protein hydroperoxides. Most likely, in vivo, ascorbate and glutathione do not inhibit the reaction of C-centered amino acid radicals with O2. Glutathione is less efficient that urate and ascorbate in repairing protein radicals; furthermore, the resulting glutathiyl radical is harmful. Ascorbate may be the more important repair agent in cells and tissues characterized by high ascorbate concentrations, such as the lens and brain; urate may be mainly responsible for repair in tissue compartments with higher urate concentrations, such as in plasma and saliva.  相似文献   
59.
60.
The novel μ3-oxo-bridged heterotrinuclear iron(III)-copper(II) trichloroacetates of the composition [Fe2CuO(CCl3COO)6(THF)3] (1a) and [Fe2CuO(CCl3COO)6(4-DMAP)3] (1b) have been synthesized and characterized by X-ray crystallography, IR and Mossbauer spectroscopy. These clusters were used as precursors for the synthesis of the nanosized catalytic system (~5–6 nm of γ-Fe2O3/CuO), which works as an efficient organic phase catalyst (~0.02 mol%) in a one-pot three component Biginelli synthesis.  相似文献   
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