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21.
River-groundwater interactions show strong scale-dependencies and are often strongly transient. In this regard, small-scale flow conditions in the hyporheic zone at the interface between surface- and groundwater can be important for process-understanding. This especially includes questions concerning flow conditions in salmonid redds of gravel-bed rivers. The Swiss subalpine river Enziwigger was chosen as an example for a small channelized river with artificial steps within the riverbed. Several methods were developed, tested and combined that capture the four dimensions (three spatial and one temporal) of the interactions between surface water, the hyporheic zone and groundwater, for individual river segments. The setup of a monitoring network as well as the realization of field-measurements provided data for groundwater flow models. Continuous time series of hydraulic data, temperature and electrical conductivity within the river and the riverbed, as well as within the riverine groundwater, allowed identifying zones with significant exchange of surface water and groundwater. Additionally, the data helped describe the transient character of groundwater flow-paths under various hydrological boundary conditions. Results of the field-measurements in combination with transient groundwater flow modeling and scenario analyses illustrate the relevance of dynamically changing infiltration and exfiltration patterns within the riverbed.  相似文献   
22.
The importance of resilience is contextualized within the sustainable long-term management of the built environment. The built environment is considered as a set of different capitals (natural, physical, economic, social and cultural) with limited possibilities for substitution between the capitals. Resilience is related to other concepts used in the search for a sustainable development of the built environment: continuity, stability and equilibrium, duration and durability, robustness and vulnerability, fast- and slow-moving risks. Cultural capital (in its material and intangible forms) as well as natural capital are significant due to long foresight considerations, high uncertainty and limitations on substitutions. Different time and scale categories and the conservation of different capitals need different anticipation and resilience strategies. It is argued that natural and cultural capitals can be transmitted if they are conservatively used and if adaptation occurs slowly. Specific strategies are needed for the ‘non-recoverability’ of cultural capital.  相似文献   
23.
A numerical scoring system to predict credit payment was developed from the payment records of customers of a large Los Angeles department store. The following types of items were used: number of payments of less than amount due, number of payments missed completely, number of collection notices previously sent, etc. Results showed good (rbi = .71) ability to discriminate between potentially good accounts and those likely to require special collection efforts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
24.
Two cave-ins occurred in the Päijänne Tunnel, the repair of both being completed in the spring of 1999. One cave-in occurred near Hämeenkoski and the other near Pulkkila. The Hämeenkoski cave-in was probably caused by the accelerated weathering of a weakness zone, which led to a rather complex cave-in process. The construction of the tunnel in the 1970s changed the groundwater conditions, thus increasing the rate of weathering. The Hämeenkoski cave-in was repaired by a bypass tunnel. The Pulkkila cave-in was caused by a water flow, which flushed out joint fillings, leading to the fall of key-blocks. The Pulkkila cave-in was repaired by penetrating the cave-in.  相似文献   
25.
The Radiation Assessment Detector (RAD) on-board NASA’s Mars Science Laboratory (MSL) rover will measure charged particles as well as neutron and gamma radiation on the Martian surface. Neutral particles are an important contribution to this radiation environment. RAD measures them with a CsI (Tl) and a plastic scintillator, which are both surrounded by an anticoincidence. The incident neutron/gamma spectrum is obtained from the measurements using inversion methods which often fit a functional behavior, e.g., a power law, to the measured data applying the instrument response function and, e.g., a least-squares method. In situations where count rates are small, i.e., where the stochastic nature of the measurement is evident, maximum likelihood estimates with underlying Poissonian statistics improve the resulting spectra. We demonstrate the measurement and inversion of gamma/neutron spectra for a detector concept featuring one high-density scintillator and one high-proton-content scintillator. The applied inversion methods derive the original spectra without any strong assumptions of the functional behavior. Instrument response functions are obtained from Monte-Carlo simulations in matrix form with which the instrument response is treated as a set of linear equations. Using the response matrices we compare a constrained least-squares minimization, a chi-squared minimization and a maximum likelihood method with underlying Poissonian statistics. We make no assumptions about the incident particle spectrum and the methods intrinsically satisfy the constraint of non-negative counts. We analyzed neutron beam measurements made at the Physikalisch Technische Bundesanstalt (PTB) and inverted the measurement data for both neutron and gamma spectra. Monte-Carlo-generated measurements of the expected Martian neutron/gamma spectra were inverted as well, here the maximum likelihood method with underlying Poissonian statistics produces significantly better results.  相似文献   
26.
OBJECTIVE: If lungs could be retrieved for transplant after circulatory arrest, the shortage of donors might be significantly alleviated. Great controversy still exists concerning the optimal mode of preservation of pulmonary grafts in these non-heart-beating donors. METHODS: Graft function was measured in an isolated room air-ventilated rabbit lung model during reperfusion with homologous, diluted (Hb +/- 8.0 g/dl) and deoxygenated (PaO2 +/- 40 mmHg) blood up to 4 h. Five groups of cadavers (n = 4 in each group) were studied: In the control group, lungs were immediately reperfused. In the other groups, cadavers were left at room temperature for 4 h after death with lungs either deflated (group 1), inflated with room air (group 2), or ventilated with room air (group 3) or 100% nitrogen (group 4). RESULTS: After 1 h of reperfusion, significant differences were noted between group 1 and groups 2, 3, and 4 in peak airway pressure (27 +/- 5 cm H2O vs. 15 +/- 1 cm H2O, 17 +/- 2 cm H2O, and 16 +/- 1 cm H2O, respectively; P < 0.05), in weight gain (137 +/- 24 vs. 31 +/- 7, 30 +/- 3, and 30 +/- 2%, respectively; P < 0.05), and in veno-arterial oxygen pressure gradient (9 +/- 5 vs. 95 +/- 13, 96 +/- 7 and 96 +/- 4 mmHg, respectively; P < 0.05). Also, wet-to-dry weight ratio at end of reperfusion was significantly different (10.2 +/- 1.0 vs. 6.0 +/- 0.3. 5.2 +/- 0.3 and 5.4 +/- 0.5, respectively; P < 0.05). No significant differences in any of these parameters were observed between groups 2, 3, and 4. CONCLUSIONS: These data suggest that: (1) pulmonary edema will develop in atelectatic lungs if reperfusion is delayed for 4 h after death; (2) postmortem room air-inflation is as good as ventilation in prolonging warm ischemic tolerance; (3) ventilation with room air is no different from that with nitrogen; (4) therefore, prevention of alveolar collapse appears to be the critical factor in protecting the warm ischemic lung from reperfusion injury independent of continuous oxygen supply.  相似文献   
27.
BACKGROUND: If lungs could be retrieved for transplantation from non-heart-beating cadavers, the shortage of donors might be significantly alleviated. METHODS: Peak airway pressure, mean pulmonary artery pressure, pulmonary vascular resistance, and wet to dry weight ratio were measured during delayed hypothermic crystalloid flush in rabbit lungs (n = 6) at successive intervals after death comparing cadavers with lungs left deflated (group 1), inflated with room air (group 2) or 100% oxygen (group 4), or ventilated with room air (group 3), or 100% nitrogen (group 5), or 100% oxygen (group 6). RESULTS: There was a gradual increase in mean pulmonary artery pressure and pulmonary vascular resistance with longer postmortem intervals in all study groups (p = not significant, group 1 versus group 2 versus group 3). There was also a gradual increase in peak airway pressure and wet-to-dry weight ratio over time in all groups, which reflected edema formation during flush (airway pressure, from 14.5 +/- 1.0 cm H2O to 53.7 +/- 12.2 cm H2O, and wet-to-dry weight ratio, from 3.6 +/- 0.1 to 11.5 +/- 1.2, in group 1 at 0 and 6 hours postmortem, respectively; p < 0.05). Compared with group 1, however, the increase in groups 2 and 3 was much slower (airway pressure, 20.9 +/- 0.5 cm H2O and 18.8 +/- 1.2 cm H2O, and wet-to-dry weight ratio, 5.2 +/- 0.3 and 4.6 +/- 0.4 at 6 hours postmortem, respectively; p < 0.05 versus group 1 and p = not significant, group 2 versus group 3). Airway pressure and wet-to-dry weight ratio did not differ between groups 2 and 4 or between groups 3, 5, and 6. CONCLUSIONS: These data suggest that (1) pulmonary edema will develop in atelectatic lungs if hypothermic flush is delayed for 2 hours after death, (2) postmortem inflation is as good as ventilation in prolonging warm ischemic tolerance, (3) inflation with oxygen or ventilation with nitrogen or oxygen is no different from that with room air, and (4) therefore, prevention of alveolar collapse appears to be the critical factor in protecting the lung from warm ischemic damage independent of continued oxygen delivery.  相似文献   
28.
A procedure for the constant potential electrodeposition of rhodium onto nickel electrodes, the subsequent surface characterizations, and electrochemical evaluation is presented. The resulting Ni/Rh electrodes were evaluated for their activity as anode catalysts for the electro-oxidation of urea. A detailed procedure for the electrodeposition of Rh onto Ni foil is provided. It is shown that the electrocatalytic performance of Ni/Rh electrodes on the oxidation of urea in alkaline medium is primarily influenced by two electrodeposition parameters: the applied electrodeposition potential and the loading of Rh (mg?cm?2). An optimization for electrocatalytic performance based on the electrodeposition potential and Rh loading is demonstrated. The effect of these parameters on visual finish, surface morphology, and crystal structure was also studied.  相似文献   
29.
Recent studies have shown that dissolved organic matter (DOM) may inhibit the excited triplet-induced oxidation of several aromatic water contaminants, in particular those containing an aniline functionality. Such an inhibition was ascribed to antioxidant moieties of DOM. The present study was conducted with the aim of verifying whether well-defined antioxidants could act as inhibitors in analogy to DOM. Various substituted phenols exhibiting antioxidant character were able, at micromolar concentration, to slow down the photoinduced depletion of several anilines and sulfonamides in aerated aqueous solution containing 2-acetonaphthone as the photosensitizer. A concomitant accelerated degradation of the phenols in the presence of such contaminants was observed. This reinforces the hypothesis of reduction of oxidation intermediates of the contaminants by the phenols. Phenol (unsubstituted) was found to be a useful inhibitor even in the case of DOM-photosensitized transformations. Phenolic antioxidants are proposed as diagnostic tools to investigate the aquatic photochemistry of aromatic amines.  相似文献   
30.
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