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131.
In this work we report the results of a combined biochemical and electrochemical study aimed to analyze both the growth of biofilms of Pseudomonas fluorescens on copper samples and its possible role in the instability of the metal/electrolyte interface.DNA and RNA were quantified along the time for biofilms grown on copper and glass to estimate both the growth of the bacterial population and its metabolic state (through the RNA/DNA ratio). The expression and specific activity of catalase were also determined to gain insight into their possible role in corrosion acceleration. The electrochemical behavior of the biofilm/copper interface was monitored by Linear Polarization Resistance (Rp) and electrochemical impedance spectroscopy (EIS) along the experiments.Results showed a longer lag phase for biofilms developing on copper that included a period of high metabolic activity (as measured by the RNA/DNA ratio) without biomass growth. Biological activity introduced a new time constant at intermediate frequencies in EIS spectra whose capacitive behavior increased with the biofilm development. The increment in this biofilm-related signal was accompanied by a strong limitation to charge transfer through a diffusion controlled process probably due to oxygen exhaustion by cells respiration, while the resistance of the interface decreased presumably due to oxide dissolution by local acidification under the colonies. In addition, catalase activity was found to be high in mature copper-tolerant biofilms, which differentially express a catalase isoform not present in biofilms growing on glass. 相似文献
132.
The paper presents a new approach to deal with combinatorial problems. It makes use of a biological analogy inspired by the performance of viruses. The replication mechanism, as well as the hosts’ infection processes is used to generate a metaheuristic that allows the obtention of valuable results. The viral system (VS) theoretical context is described and it is applied to a library of medium-to-large-sized cases of the Steiner problem for which the optimal solution is known. The method is compared with the metaheuristics that have provided the best results for the Steiner problem. The VS provides better solutions than genetic algorithms and certain tabu search approaches. For the most sophisticated tabu search approaches (the best metaheuristic approximations to the Steiner problem solution) VS provides solutions of similar quality. 相似文献
133.
Pablo Guillermo Gonzales-Ormeo Cludio Geraldo Schn 《Journal of Alloys and Compounds》2009,470(1-2):301-305
The metastable phase diagram of the BCC-based ordering equilibria in the Ti–Fe system has been calculated using a truncated cluster expansion, through the combination of FP-LAPW and cluster variation method (CVM) in the irregular tetrahedron cluster approximation. The results are compared with phenomenological CVM assessments of the system and suggest that the value for the experimental formation enthalpy of the B2-TiFe compound should be significantly more negative than the currently assessed value. 相似文献
134.
Nicolas Magdelaine Pablo S. Rivadeneira Lucy Chaillous AnneLaure FournierGuilloux Michel Krempf Taghreed MohammadRidha Mourad AitAhmed Claude H. Moog 《IET systems biology》2020,14(1):16
Driving blood glycaemia from hyperglycaemia to euglycaemia as fast as possible while avoiding hypoglycaemia is a major problem for decades for type‐1 diabetes and is solved in this study. A control algorithm is designed that guaranties hypoglycaemia avoidance for the first time both from the theory of positive systems point of view and from the most pragmatic clinical practice. The solution consists of a state feedback control law that computes the required hyperglycaemia correction bolus in real‐time to safely steer glycaemia to the target. A rigorous proof is given that shows that the control‐law respects the positivity of the control and of the glucose concentration error: as a result, no hypoglycaemic episode occurs. The so‐called hypo‐free strategy control is tested with all the UVA/Padova T1DM simulator patients (i.e. ten adults, ten adolescents, and ten children) during a fasting‐night scenario and in a hybrid closed‐loop scenario including three meals. The theoretical results are assessed by the simulations on a large cohort of virtual patients and encourage clinical trials.Inspec keywords: biochemistry, medical control systems, blood, diseases, medical computing, closed loop systems, biomedical equipment, state feedback, patient treatment, patient monitoring, biomedical measurement, physiological models, sugarOther keywords: fasting‐night scenario, hybrid closed‐loop scenario, hypoglycaemia‐free artificial pancreas project, blood glycaemia, euglycaemia, type‐1 diabetes, control algorithm, guaranties hypoglycaemia avoidance, pragmatic clinical practice, state feedback control law, required hyperglycaemia correction bolus, rigorous proof, control‐law, glucose concentration error, hypo‐free strategy control 相似文献
135.
Marta Francisco Pablo Velasco Diego A. Moreno Cristina García-Viguera María Elena Cartea 《Food research international (Ottawa, Ont.)》2010,43(5):1455-1463
Cooking Brassica vegetables as a domestic processing method has a great impact on health-promoting bioactive compounds: glucosinolates (GLS), flavonoids, hydroxycinnamic acids, and vitamin C. In Galicia (NorthWestern Spain), one of the most consumed horticultural crops is Brassica rapa, by using the leaves (turnip greens) and the young sprouting shoots (turnip tops) in different culinary preparations. In order to determine the effect of cooking, on turnip greens and turnip tops, bioactive GLS, flavonoids, hydroxycinnamic acids and vitamin C were analysed and simultaneously determined. The level of retention of each individual compound after cooking procedures was evaluated in the edible organs, and also in the cooking water, in order to compare their composition to a fresh uncooked control. Steaming, conventional boiling, and high-pressure cooking, traditional processing methods of this kind of vegetables, were the three domestic processing methods used in this work. Results showed that total GLS and phenolics were significantly affected by the cooking procedure and the loss rate varied among individual compounds. Steaming was the method that better preserved GLS and phenolic compounds. Conventional boiling and high-pressure cooking methods presented similar rate of losses of total GLS content (64%) and total phenolic content (more than 70%). Degradation among glucosinolate classes, aliphatic or indolic, was similar. The total flavonoids lost in turnip greens were 64% and 67% for conventional boiling and high-pressure, respectively. The main losses were caused by leaching into the cooking water. The concentration of vitamin C suffered a drastic loss in the process of sample handling and after cooking. Despite the fact that any cooking procedure affected negatively the nutritional composition of the turnip greens and tops, our results showed high retentions of individual compounds in steaming, and the lowest retentions were obtained in the traditional high-pressure cooking. High retention of health-promoting compounds in the cooking water should be considered for increasing the intake of properties of B. rapa. 相似文献
136.
137.
The Extended Gate Field Effect Transistor (EGFET) is a device composed of a conventional ion-sensitive electrode and a MOSFET
device, which can be applied for the measurement of ion content in a solution. The EGFET is fabricated connecting the sensitive
membrane to a commercial MOSFET. We investigated the use of fluorine-doped tin oxide films (FTO) as sensitive membrane to
EGFET. The commercial FTO shows a low resistivity and a crystalline structure, both determined using conductivity set-up and
X-ray diffraction experiments, respectively. So far, it has been known that an amorphous structure is desirable to obtain
high sensitivity. Despite of the a crystalline structure, we have fabricated the FTO as EGFET for pH sensor and carried out
experiments in order to obtain the response of the device inserted into solutions with pH values from 2 up to 12. In this
range, we have quantified a sensitivity of 50 mV/pH, which may have large potential applications as pH and biosensors. In
addition, both the film and the structure of the sensor are cheaper and easier to make than in common techniques. 相似文献
138.
Albert Albers Tobias Deigendesch Hans-Georg Enkler Stefan Hauser Pablo Leslabay Jochen Oerding 《Microsystem Technologies》2008,14(12):1781-1787
Miniaturization of macroscopic mechanical systems enables the opening of new areas of application for micro technological
systems. Because of technological restrictions, especially when applying miniaturized conventional manufacturing techniques,
shape and material deviations cannot be scaled down in the same dimension like micro parts. Thus, the long-term objective
is to ensure the functioning by appropriate design measures. In doing so, determination of the transfer behavior by modeling
and simulation is required. This work presents two ways for ensuring the required properties of micro gears and describes
how the results do correlate. The experimental way uses the radial composite inspection as it is used in the macroscopic world.
The simulative way deploys a rolling simulation by utilization of finite element analysis. The virtual prototypes are originated
on measured real test gears. When comparing experiment and simulation of the rolling behavior, in some short and long wave
areas deviations can be recognized. These can be ascribed to the reduction from three to two dimensions when modeling. Other
deviations might be based on inaccuracies when mounting into the test rig. In other areas quite good correlations of test
and simulation could be ascertained. 相似文献
139.
A model to explain and predict market-driven investment in renewable energy capital is proposed. The model is suitable for application to the biomass, wind, solar and ocean-derived energy industries. It basically assumes that, given a set of prices and a specific technology, the marginal efficiency of capital invested in these industries only depends on the productivity of the project's site and on its energy transport distance. As suggested by traditional investment theory, the model supposes that only those projects offering marginal efficiencies of capital above the current available rate of interest would be implemented, thus demarcating a region in the productivity–energy transport distance space where all the economically viable projects should lie. By relating this region to the geographic space available for development, total potential investment can be deduced. By using cash flows defined in variable energy transport distance and mean wind speed, a case study for the Chilean wind energy industry is presented. The use of the model to analyse the effect of alternative support schemes for wind energy in Chile is briefly demonstrated. It is concluded that for increasing the area economically available for the development of new wind farms, a research and development support scheme aimed at reducing investment cost of wind turbines by 25% is equivalent to a 20% price subsidy on energy. 相似文献
140.
Helene Perrotin-Brunel Pablo Cabeza Perez Jaap van Spronsen Cor J. Peters 《The Journal of Supercritical Fluids》2010,52(1):6-719
The solubility of Δ9-tetrahydrocannabinol (Δ9-THC) in supercritical carbon dioxide has been determined at 315, 327, 334 and 345 K and in the pressure range from 13.2 to 25.1 MPa using an analytical method with a quasi-flow apparatus. Prior to performing these measurements, the method was validated by measuring anthracene solubilities and comparing these with literature values. The molar solubility for Δ9-THC ranged from 0.20 to 2.95 × 10−4. The data were correlated using the Peng-Robinson equation of state in combination with quadratic mixing rules. Deviations between calculated results and the experimental data ranged from 4.1 to 13.3% absolute average relative deviation (AARD). 相似文献