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31.
Shaker RR Osaili TM Abu Al-Hasan AS Ayyash MM Forsythe SJ 《Journal of food science》2008,73(7):M354-M359
Enterobacter sakazakii is an opportunistic foodborne pathogen that has been isolated from powdered infant milk formula. This study determined the effect of desiccation, starvation, heat and cold stresses on the thermal inactivation of E. sakazakii in rehydrated infant milk formula (RIMF). Stressed cells were mixed with RIMF at 52, 54, 56, and 58 degrees C for various time periods. The D- and z-values were determined by using linear regression analysis. D-values for unstressed E. sakazakii at 52, 54, 56, and 58 degrees C were 15.33, 4.53, 2, and 0.53 min, respectively. Desiccation and heat stresses, but not starvation or cold stress, caused significant (P < 0.05) reduction in D-values. The z-values of desiccated, starved, heat stressed, and cold stressed E. sakazakii were not significantly different from unstressed cells (4.22 degrees C). Thermal resistance of E. sakazakii in RIMF is affected by the environmental stresses; that is, desiccation and heat stresses that may surround the bacterium prior to the contamination of infant formula. The results of this study may be of use to regulatory agencies, infant milk producers, and infant caregivers to design heating processes to eliminate E. sakazakii that may be present in infant milk formula. 相似文献
32.
Rare earth permanent magnets Sm(Co, Fe, Cu, Zr)z with outstanding performance and high-temperature thermal stability were fabricated. Optimized by Fe content and process, Sm(Co0.72Fe0.15Cu0.1Zr0.03)7.5 magnet with B1〉0.75 T and Hci〉1300 kA/m at 300 ℃ can be obtained. According to the performance data of Sm(Co0.72Fe0.15Cu0.1Zr0.03)7.5, the magnetic field along central axis Bz in periodic permanent magnet (PPM) focusing system was simulated using electromagnetic field analysis software Maxwell 2D/3D. The Bz exhibited typical cosine curve along central axis, and the peak value of Bz was high enough to meet the demand of PPM focusing system at room temperature even at 200±20 ℃. Additionally, a kind of simple cooling structure for PPM focusing system was designed by setting cooling pipe between polepieces. Simulated results showed that smooth cosine curve of Bz was successfully achieved with good control of the thickness of cooling pipe. 相似文献
33.
We have measured the temperature and polarization dependence of Silin spin wave spectra in a saturated 3He–4He mixture with a concentration of 9.4% at a pressure of 8 bars. The mixture has been cooled and polarized by a Leiden dilution
refrigerator to temperatures in the range 10–15 mK and polarizations as high as 9.2% corresponding to 3.4 times the equilibrium
polarization of 2.7% in the external magnetic field of 11.36 T. The analysis takes into account the dipolar interactions and
results in the relaxation time τ
⊥
and spin diffusion constant D
⊥
. We find that τ
⊥
and D
⊥
are proportional to
where T is the temperature,
is the polarization enhancement factor and T
a0 is the anisotropy temperature for the mixture at equilibrium in the external field. Our result T
a0=3.66±0.14 mK is 30% higher than the theoretical prediction for very dilute mixtures and is evidence for the existence of
polarization induced relaxation of transverse spin currents. 相似文献
34.
35.
D. Wittwer F.Sh. Abdullin Yu.V. Albin S.N. Dmitriev R. Eichler H.W. Gäggeler R.A. Henderson J.M. Kenneally Yu.V. Lobanov Yu.Ts. Oganessian A.N. Polyakov P. Rasmussen A. Serov I.V. Shirokovsky S.V. Shishkin M.A. Stoyer E.E. Tereshatov V.K. Utyonkov M. Wegrzecki 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(1):28-1519
Currently, gas phase chemistry experiments with heaviest elements are usually performed with the gas-jet technique with the disadvantage that all reaction products are collected in a gas-filled thermalisation chamber adjacent to the target. The incorporation of a physical preseparation device between target and collection chamber opens up the perspective to perform new chemical studies. But this approach requires detailed knowledge of the stopping force (STF) of the heaviest elements in various materials. Measurements of the energy loss of mercury (Hg), radon (Rn), and nobelium (No) in Mylar and argon (Ar) were performed at low kinetic energies of around (40-270) keV per nucleon. The experimentally obtained values were compared with STF calculations of the commonly used program for calculating stopping and ranges of ions in matter (SRIM). Using the obtained data points an extrapolation of the STF up to element 114, eka-lead, in the same stopping media was carried out. These estimations were applied to design and to perform a first chemical experiment with a superheavy element behind a physical preseparator using the nuclear fusion reaction 244Pu(48Ca; 3n)289114. One decay chain assigned to an atom of 285112, the α-decay product of 289114, was observed. 相似文献
36.
A.F. Qasrawi 《Materials Science and Engineering: B》2013,178(12):851-856
In this work, the design and characterization of magnesium oxide based tunneling diodes which are produced on Al and InSe films as rectifying substrates are investigated. It was found that when Al thin films are used, the device exhibit tunneling diode behavior of sharp valley at 0.15 V and peak to valley current ratio (PVCR) of 11.4. In addition, the capacitance spectra of the Al/MgO/C device show a resonance peak of negative capacitance (NC) values at 44.7 MHz. The capacitance and resistance–voltage characteristics handled at an ac signal frequency of 100 MHz reflected a build in voltage (Vbi) of 1.29 V and a negative resistance (NR) effect above 2.05 V. This device quality factor (Q)–voltage response is ~104. When the Al substrate is replaced by InSe thin film, the tunneling diode valley appeared at 1.1 V. In addition, the PVCR, NR range, NC resonance peak, Q and Vbi are found to be 135, 0.94–2.24 and 39.0 MHz, ~105 and 1.34 V, respectively. Due to the wide differential negative resistance and capacitance voltage ranges and due to the response of the C/MgO/InSe/C device at 1.0 GHz, these devices appear to be suitable for applications as frequency mixers, amplifiers, and monostable–bistable circuit elements (MOBILE). 相似文献
37.
Kamonpatana K Giusti MM Chitchumroonchokchai C MorenoCruz M Riedl KM Kumar P Failla ML 《Food chemistry》2012,135(2):738-747
Some fruits and their anthocyanin-rich extracts have been reported to exhibit chemopreventive activity in the oral cavity. Insights regarding oral metabolism of anthocyanins remain limited. Anthocyanin-rich extracts from blueberry, chokeberry, black raspberry, red grape, and strawberry were incubated ex vivo with human saliva from 14 healthy subjects. All anthocyanins were partially degraded in saliva. Degradation of chokeberry anthocyanins in saliva was temperature dependent and decreased by heating saliva to 80 °C and after removal of cells. Glycosides of delphinidin and petunidin were more susceptible to degradation than those of cyanidin, pelargonidin, peonidin and malvidin in both intact and artificial saliva. Stability of di- and tri-saccharide conjugates of anthocyanidins slightly, but significantly, exceeded that of monosaccharide compounds. Ex vivo degradation of anthocyanins in saliva was significantly decreased after oral rinsing with antibacterial chlorhexidine. These results suggest that anthocyanin degradation in the mouth is structure-dependent and largely mediated by oral microbiota. 相似文献
38.
Thermal Inactivation of Microorganisms 总被引:1,自引:0,他引:1
This paper serves as an overview of various aspects of thermal processing. Heat processing of foods has a long history and is still one of the most important preservation methods. To guarantee microbiological safety and stability, large safety margins are often applied in traditional heat processes. Because of the need for more fresh like foods, there is a need for milder preservation methods without compromising on safety and stability. The review deals with heat resistance data and mathematical models that describe heat inactivation. The effects of food composition are not yet fully clear and more knowledge of the cell physiology of the target microorganism could be of help in predicting the effects of food constituents. Finally, special attention has been paid to biological time temperature indicators to enable proper process calculations. 相似文献
39.
40.
There are many multi‐input multi‐output (MIMO) systems in chemical plants, and they have multiple time delays of different length in each input and output pair. This paper explains a two‐degree‐of‐freedom (2DOF) control system based on generalized minimum variance control (GMVC) for MIMO systems. It can improve the tracking performance with respect to the reference signals and the response properties for the disturbance. The states between the sampling period can be expressed by using the modified z transform to take account of multiple time delays. Additionally, a tracking controller is designed to decouple the plant. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(1): 28–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21046 相似文献