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991.
On the basis of the positive outcome of animal experiments, several large placebo-controlled trials are underway and aiming for the first time at the prevention of an immune-mediated disease, type 1 diabetes. The first of these trials, The Deutsche Nicotinamide Intervention Study (DENIS), evaluated the clinical efficacy of high doses of nicotinamide in children at high risk for IDDM. Nicotinamide has been shown to protect beta-cells from inflammatory insults and to improve residual beta-cell function in patients after onset of IDDM. Individuals at high risk for developing IDDM within 3 years were identified by screening the siblings (age 3-12 years) of patients with IDDM for the presence of high titer (> or =20 Juvenile Diabetes Foundation [JDF] U) islet cell antibodies. Probands (n = 55) were randomized into placebo and nicotinamide (slow release, 1.2 g x m(-2) x day(-1)) receiving groups and followed prospectively in a controlled clinical trial using a sequential design. Rates of diabetes onset were similar in both groups throughout the observation period (maximum 3.8 years, median 2.1 years). This sequential design provides a 10% probability of a type II error against a reduction of the cumulative diabetes incidence at 3 years from 30 to 6% by nicotinamide. The trial was terminated when the second sequential interim analysis after the eleventh case of diabetes showed that the trial had failed to detect a reduction of the cumulative diabetes incidence at 3 years from 30 to 6% (P = 0.97). The group receiving nicotinamide exhibited decreased first-phase insulin secretion in response to intravenous glucose (P = 0.03). No other side effects were observed. We conclude that in this subgroup of diabetes-prone individuals at very high risk and with an assumed rapid disease progression, nicotinamide treatment did not cause a major decrease or delay of diabetes development. However, the data do not exclude the possibility of a less strong, but potentially meaningful, risk reduction in this cohort, or a major clinical effect of nicotinamide in individuals with less risk of progression to IDDM than studied here.  相似文献   
992.
The influence of selected properties of fly ash on the measurements of an on-line analyser was described. Fly ash studied in the research originated from the pulverized coal fired boiler. The samples were taken using an inspection method within a period of 3 months. Systematic observation of the properties of the ash allowed monitoring of the work of the industrial analyzer during a relatively long period of the power plant work. Samples of coal fly ash were examined for their chemical and physical properties. Morphology was analysed by scanning electron microscopy. Unburned carbon content in fly ash was determined by using loss-on-ignition (LOI) and thermogravimetry analysis (TGA). The particle size distribution of fly ash was examined. Correlation between laboratory and on-line industrial measurements of the unburned carbon content of ash was discussed.  相似文献   
993.
Several polish herbal medicaments were studied to determine trace elements and their bioavailable forms by the use of the ICP-AES method. The contents of Al, B, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, P, Pb, Se, Si, Ti, V and Zn were determined. The total concentrations were measured in samples mineralised with concentrated nitric acid and hydrogen peroxide in a microwave system. The one-step extraction was applied, using, as extractants: deionised water, diluted hydrochloric acid and buffer solution containing pepsin. Efficiencies of the leaching versus time were investigated. The extraction efficiencies were analysed, taking into account bioavailability of elements under conditions simulating digestion processes in the alimentary system. The contents of the examined elements in prescribed amounts of medication, were compared to the nutritional requirements and daily permissible dose. The results are considered in terms of the utility of the natural herbal medicaments as a source of minerals indispensable for proper functioning of the human organism. Some points of merit (precision of measurements, accuracy by Standard Reference Material analysis) are also considered.  相似文献   
994.
Based on results of pilot scale research with source-separated black water (BW) and grey water (GW), a new sanitation concept is proposed. BW and GW are both treated in a UASB (-septic tank) for recovery of CH4 gas. Kitchen waste is added to the anaerobic BW treatment for doubling the biogas production. Post-treatment of the effluent is providing recovery of phosphorus and removal of remaining COD and nitrogen. The total energy saving of the new sanitation concept amounts to 200 MJ/year in comparison with conventional sanitation, moreover 0.14 kg P/p/year and 90 litres of potential reusable water are produced.  相似文献   
995.
This paper presents the results of SSC (Sulfide Stress Cracking) investigations of duplex stainless steel 2205 resistance to cracking failure under the combined action of tensile stress and aqueous environments containing hydrogen sulfide according to the NACE Standard TM0177-96. The investigations were carried out on 9 test pieces that were loaded with a tensile stress ranging from 1.02 × the yield stress (YS) to 0.72 × YS. The tests were terminated either when the test specimen failed or after 720 h (30 days) – whichever occurred first – in accordance with the standard requirements. Only two of the specimens examined, one loaded with 1.02 × YS and the second one with 0.72 × YS, failed during the test. The resulting fracture surfaces were subjected to qualitative and quantitative fractographic examinations. Quantitative fracture analysis included an estimation of such parameters as linear roughness index RL, fractal dimension DF and overlap index OL.  相似文献   
996.
A new method for the preparation of new heterocyclic amine surfactants based on sulfobetaines is proposed. Interfacial activities of the surfactants obtained in aqueous solution were studied by surface tension measurements. The critical micelle concentration, surface excess concentration, minimum area per surfactant molecule, and standard Gibbs energy of adsorption were determined. The adsorption properties of these compounds depend significantly on the alkyl chain length. Alkyl chain length also affects biological properties of the new surfactants, determining the minimum inhibitory concentration and size of inhibited growth zone. The compounds have high antimicrobial activity.  相似文献   
997.
998.
In the first stage, carbon materials were manufactured from chitin and chitosan as the main precursor. Chitin and chitosan were impregnated with Cu2+ ions. Using heat treatment, the organic matter (biopolymers) was transformed into a porous carbon matrix, while copper ions were transformed into copper‐based nano‐crystallites containing copper atoms in a +1 and 0 oxidation state. Such synthesized carbons exhibited high contact antifungal activity, e.g., for sample, CH‐ACu0.1_Ox against R. nigricans the inhibition zone is 10.27 mm. In the second stage, composite polymer films were manufactured by mixing polylactide (PLA) and the obtained microbial carbon material (up to 3 wt % Cu‐carbon content). Despite the very low content of carbon material (3 wt %), the composite PLA films exhibited excellent microbial properties for selected bacteria and fungi, e.g., sample CuCM3%/PLA demonstrated high log10 reduction values of 2.17 and 2.66 for the strains of E. coli and S. aureus, respectively. The composite films, and their components, were examined by means of diversified physicochemical methods like low temperature adsorption of nitrogen, SEM, elemental analysis, XRD, cyclic voltammetry, antifungal, and antibacterial analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43429.  相似文献   
999.
Drainage wells used in lignite mining have to be operated at high efficiency in order to achieve a targeted drawdown in the shortest time period possible. However, oversizing of pump units and excessive pumping can cause accelerated aging of wells and over time, decrease a well’s drainage efficiency. This article analyzes the case of a well that was operated for 10 years and then abandoned at a lignite mine. A common practice in installing dewatering wells in Poland is to protect the well screen with a pre-fabricated granular layer (called a “gravel coat”) that is attached to the screen when it is lowered into the hole. The combination of the gravel coat and well screen is surrounded by a protective gravel pack. Samples of the gravel coat were obtained from the abandoned well. The percentage by weight of precipitates in, and the porosity of the gravel coat from the abandoned well were determined and compared with the properties of new gravel coat material. Tests were conducted in the laboratory to compare hydraulic losses, apparent seepage velocity, effective velocity, and the hydraulic efficiency of the well’s gravel coat. The results of the tests explain the low hydraulic efficiency of the abandoned well and the origin of the damage to the gravel coat. The actual yield was also compared with the calculated theoretical safe yield, which was estimated based on the results of geological records from the construction of the well.  相似文献   
1000.
Surfactants are important ingredients of personal care products and household products. The main characteristic of these compounds is to decrease the surface tension of solvent and resulting many properties such as contact angle, foam properties etc. The coexistence of other ingredients in the product may affect the properties of surfactants. One of the main components contained in almost every personal care and household product is sodium chloride. The main aim of this work was to determine the effect of this salt on some surface and usage properties of cocamidopropyl betaine (CAPB). From our experiments it was shown that the effect of added sodium chloride in the aqueous solutions of CAPB on the properties is the opposite to the one described in the literature for cationic and anionic surfactants, i.e., CMC increases with increasing ionic strength, foam height decreases with increasing salt concentration. Our investigation showed that sodium chloride makes worse the properties of the CAPB solutions examined in this work.  相似文献   
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