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61.
Novy J Becvarova P Skorpikova J Mornstein V Janisch R 《Microscopy research and technique》2005,68(1):1-5
Cytoskeletal structures can be affected by external factors including ultrasound. Our task was to develop a structure analysis method to evaluate these changes quantitatively. We exposed HeLa cells to continuous ultrasound (1 MHz, 1 and 2 W/cm2, 10 min at 37 degrees C). The microtubules were detected by the monoclonal antibody TU-01/SwAM/FITC, observed in a fluorescence microscope and photographed digitally. The images were processed by "FFT magic" software. The structure analysis is based on frequency domain filtering using discrete Fourier transform. The basic idea is to design filters to extract information describing best the structural changes. The properties of the filter can be enhanced by direction filtering, i.e., extraction of a symmetric angular segment in the frequency domain centered on a zero frequency. The final image is a normalized sum of inverse FFT's of such segmented spectra. We needed a method yielding a single number assigned to the structure, e.g., the ratio of the area of microtubules to the total cell area. Assuming that the image background intensity is constant, we can use thresholding to detect areas occupied by the cells. The information about the area of the microtubules is contained in a wide range of higher intensities. Therefore, we use a gamma correction. The area occupied by microtubules is then considered an area with intensities above the selected threshold. There were tested three different filters to extract information about microtubules. The mathematical method chosen seems sensitive enough for quantitative assessment of changes of the microtubular network. 相似文献
62.
Karasek M. Kanka J. Bohac L. Krcmarik D. Radil J. Vojtech J. 《Lightwave Technology, Journal of》2007,25(3):664-672
In this paper, the effect of addition and/or dropping of wavelength-division-multiplexed channels in an all- optical gain-clamped (AOGC) second-order (SO) pumped lumped Raman fiber amplifier (LRFA) has been investigated experimentally and analyzed by numerical simulation. Channel addition/ removal was simulated by transmitting ten signals through a counter-directionally pumped LRFA consisting of a 16-km-long dispersion-compensating fiber. The light from eight lasers was square-wave modulated at 500 Hz; power transients of the surviving channels caused by cross-gain modulation of the LRFA were monitored at the output of the amplifier. All-optical feedback loop was implemented in the form of a ring laser. Gain-clamping properties of the SO-pumped LRFA are compared with those of the first-order pumped LRFA having the same ON/OFF Raman gain. Theoretical analysis of the AOGC LRFA was based on numerical solution of coupled propagation equations for the backward propagating pump, signals, and both forward and backward propagating spectral components of amplified spontaneous emission powers. 相似文献
63.
64.
The hypolipidemic drug clofibrate is known to affect the hepatic transport of various organic anions including bilirubin,
fatty acids and sulfobromophthalein. Changes in the rate of metabolism and/or intracellular transport have been claimed responsible
for the effect. To evaluate these possibilities, the transport of sulfobromophthalein-glutathione, a model compound that does
not require metabolism for biliary excretion, was studied in perfused livers isolated from clofibrate-treated and control
rats. Cytosolic fatty acid binding protein and glutathione S-transferase activity were also measured. Clofibrate treatment
significantly increased liver weight; as a result glutathione S-transferase activity (toward 1-chloro-2,4-dinitrobenzene)
fell if expressed per gram of liver (4560±420 (SE) vs 7010±260 nmoles/min for clofibrate treated and controls respectively,
p<0.002), but was unchanged when expressed per total liver (60.8±6.5 vs 64.6±3.5 μmoles/min for clofibrate and controls p>0.5).
Irrespective of how it was expressed fatty acid binding protein was significantly increased by the drug treatment. Steady
state sulfobromophthalein-glutathione removal velocity was saturble with increasing concentrations of sulfobromophthalein-glutathione
in both control and clofibrate-treated livers. Steady state extraction ratio, as well as Vmax and Km for removal, did not
differ between the two groups. In keeping with other observations, these data collectively indicate that the hepatic steady
state removal of nonmetabolized compounds is not affected by clofibrate. Because the concomitant decrease in glutathione S-transferase
activity only reflects an opposite change in liver weight, it remains to be determined whether clofibrate alters the hepatic
transport of sulfobromophthalein and other compounds that are conjugated with glutathione solely by changing their rate of
metabolism. 相似文献
65.
66.
Tomas Baca Petr Stepan Vojtech Spurny Daniel Hert Robert Penicka Martin Saska Justin Thomas Giuseppe Loianno Vijay Kumar 《野外机器人技术杂志》2019,36(5):874-891
This paper addresses the perception, control, and trajectory planning for an aerial platform to identify and land on a moving car at 15 km/hr. The hexacopter unmanned aerial vehicle (UAV), equipped with onboard sensors and a computer, detects the car using a monocular camera and predicts the car future movement using a nonlinear motion model. While following the car, the UAV lands on its roof, and it attaches itself using magnetic legs. The proposed system is fully autonomous from takeoff to landing. Numerous field tests were conducted throughout the year‐long development and preparations for the Mohamed Bin Zayed International Robotics Challenge (MBZIRC) 2017 competition, for which the system was designed. We propose a novel control system in which a model predictive controller is used in real time to generate a reference trajectory for the UAV, which are then tracked by the nonlinear feedback controller. This combination allows to track predictions of the car motion with minimal position error. The evaluation presents three successful autonomous landings during the MBZIRC 2017, where our system achieved the fastest landing among all competing teams. 相似文献
67.
Markus M. Schubert Vojtech Plzak Jürgen Garche R. Jürgen Behm 《Catalysis Letters》2001,76(3-4):143-150
A comparative study of the catalytic performance and long-term stability of various metal oxide supported gold catalysts during preferential CO oxidation at 80°C in a H2-containing atmosphere (PROX) reveals significant support effects. Compared to Au/-Al2O3, where the support is believed to behave neutrally in the reaction process, catalysts supported on reducible transition metal oxides, such as Fe2O3, CeO2, or TiO2, exhibit a CO oxidation activity of up to one magnitude higher at comparable gold particle sizes. The selectivity is also found to strongly depend on the employed metal oxide, amounting, e.g., up to 75% for Au/Co3O4 and down to 35% over Au/SnO2. The deactivation, which is observed for all samples with increasing time on stream, except for Au/-Al2O3, is related to the build-up of surface carbonate species. The long-term stability of the investigated catalysts in simulated methanol reformate depends crucially on the ability to form such by-products, with magnesia and Co3O4 supported catalysts being most negatively affected. Overall, Au/CeO2 and, in particular, Au/-Fe2O3 represent the best compromise under the applied reaction conditions, especially due to the superior activity and the easily reversible deactivation of the latter catalyst. 相似文献
68.
Jarmila Kruseova David Hynek Vojtech Adam Rene Kizek Richard Prusa Jan Hrabeta Tomas Eckschlager 《International journal of molecular sciences》2013,14(6):12170-12185
Metallothioneins (MT) are low molecular weight, cysteine-rich proteins maintaining metal ions homeostasis. They play a role in carcinogenesis and may also cause chemoresistance. The aim of the study was to explore the importance of MT serum levels in children suffering from malignant tumours. This prospective study involves examination of 865 samples from 172 patients with malignant tumours treated from 2008 to 2011 at University Hospital Motol. MT serum levels were determined using differential pulse voltammetry–Brdicka reaction. Mean MT level was 2.7 ± 0.5 μM. There was no statistically significant difference between MT levels in different tumours. We also did not find any correlation between MT levels and response to therapy or clinical stages. However, we found a positive correlation between MT levels and age (p = 0.009) and a negative correlation with absolute lymphocyte number (p = 0.001). The fact that patients who had early disease recurrence had lower MT levels during the treatment (complete remission 2.67 vs. recurring 2.34, p = 0.001) seems to be important for clinical practice. Accordingly we believe that there is benefit in further studies of serum MT levels in tumours. 相似文献
69.
70.
Marketa Kominkova Petr Michalek Kristyna Cihalova Roman Guran Natalia Cernei Lukas Nejdl Kristyna Smerkova Simona Dostalova Dagmar Chudobova Zbynek Heger Radek Vesely Jaromir Gumulec Jindrich Kynicky Kledi Xhaxhiu Ondrej Zitka Vojtech Adam Rene Kizek 《International journal of molecular sciences》2015,16(4):7210-7229
In this work, we focused on the differences between bacterial cultures of E. coli obtained from swabs of infectious wounds of patients compared to laboratory E. coli. In addition, blocking of the protein responsible for the synthesis of glutathione (γ-glutamylcysteine synthase—GCL) using 10 mM buthionine sulfoximine was investigated. Each E. coli showed significant differences in resistance to antibiotics. According to the determined resistance, E. coli were divided into experimental groups based on a statistical evaluation of their properties as more resistant and more sensitive. These groups were also used for finding the differences in a dependence of the glutathione pathway on resistance to antibiotics. More sensitive E. coli showed the same kinetics of glutathione synthesis while blocking GCL (Km 0.1 µM), as compared to non-blocking. In addition, the most frequent mutations in genes of glutathione synthetase, glutathione peroxidase and glutathione reductase were observed in this group compared to laboratory E.coli. The group of “more resistant” E. coli exhibited differences in Km between 0.3 and 0.8 µM. The number of mutations compared to the laboratory E. coli was substantially lower compared to the other group. 相似文献