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411.
Copolymerization of styrene with acrylamide was carried out in an emulsifier-free aqueous medium. The resulting latex contained an appreciable amount of acrylamide-rich copolymer in the serum. The copolymerization course was divided into three stages on the basis of the main reaction locus. At first, acrylamide polymerized in preference to styrene in the aqueous phase. Water-soluble growing radicals lost hydrophilicity rapidly and nucleated the particles. After particle formation, styrene polymerized exclusively in the particles until styrene droplets disappeared. The decrease in the concentration of residual styrene monomer caused growing radicals to keep the hydrophilicity for a long time, and polymerization of acrylamide was accelerated in the aqueous phase. Polymerizations at higher temperature and lower pH resulted in prolongation of the first stage of the polymerization, that is, preferential polymerization of acrylamide in the aqueous phase. An increase in the acrylamide fraction in monomer feed caused some decreases in the particle size and its uniformity. 相似文献
412.
The photodarkening process in amorphous As-S films has been studied for different film thickness as a function of exposure time. The transient characteristics of the process are described by a set of differential equations based on a modified first-order reaction model. 相似文献
413.
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416.
A cationic colloidal iron method was introduced for electron microscopic detection of anionic sites in hydrophilic resin-embedded specimens, and the method was applied to Paneth cells of the mouse jejunum. Mouse jejunal blocks were embedded in hydrophilic acrylic resin (LR White), cut into ultrathin sections, stained with the diluted cationic colloidal iron, and exposed to osmium vapor. The jejunal tissues, including the Paneth cells, embedded in hydrophilic resin were reactive to the fine cationic colloidal iron. At pH value 1.5, fine electron dense colloidal iron deposited along the rims of the secretory granules and the Golgi apparatus of the Paneth cell. Colloidal particles distributed on the osmiophilic reticular structures in the rim and in dot-like fashion lined the border between the granular core and rim. At pH value 4.0, ribosomes reacted to cationic colloidal iron particles in addition to the granular rims and Golgi apparatus. At pH 7.0, even the cores of the secretory granules were stained. Semi-thin sections prepared from the LR White-embedded specimens and stained at pH 1.5 with the diluted (1:3 in volume) cationic colloidal iron showed sufficient Prussian blue reaction for light microscopy in the rims of Paneth granules and mucus of goblet cells. This method is therefore useful for correlative light and electron microscopic detection of tissue anionic sites, including sulfate, carboxyl and phosphate groups, at various pH values. 相似文献
417.
M Tamura Y Ueki E Ohtsuka M Oribe M Seita K Oribe M Ito 《Canadian Metallurgical Quarterly》1994,58(5):374-377
We report a patient who experienced a reversible prolongation of the QT interval and episodes of syncope while receiving probucol. A 64-year-old woman experienced syncopal attacks 8 and 11 weeks after beginning probucol treatment (500 mg twice daily). The pre-treatment ECG showed a slight prolongation of the corrected QT interval (QTc) (0.46 sec). Her QTc increased to 0.62 sec 12 weeks after beginning probucol treatment and decreased to about the baseline value (0.48 sec) 6 weeks after treatment was discontinued. Probucol is known to prolong the QT interval. A long QT interval has been linked to an increased risk of ventricular arrhythmias, syncope or sudden death. However, clinical reports which causally relate probucol treatment to syncope are very rare. Although an ECG during the episodes of syncope was not available, this patient's syncope might be due to ventricular tachyarrhythmia associated with probucol-induced QT prolongation. This case emphasizes the need for careful evaluation of the QT interval before and during probucol treatment. 相似文献
418.
Census data was analyzed for 20 municipalities along the Tohoku Line in Tokyo Megalopolis to elucidate the changes in the population structure and the commuting situation in the last two decades. The major findings were: (1) the changing pattern of population structure markedly varied among the municipalities, and (2) the long-distance commuting workers have increased particularly among those 50 km or more from central Tokyo. 相似文献
419.
420.
Yasuo Ohtsuka Tsunenori Nozawa Akira Tomita Yasukatsu Tamai Masahiro Hatano 《Fuel》1984,63(10):1363-1366
High-field, high-resolution 13C cross-polarization and magic angle spinning nuclear magnetic resonance experiments are reported on Yallourn brown coal and on products obtained from the coal by heat treatment. The spectral resolution at 75 MHz is much improved over that previously reported for lower frequencies. A comparison of experimental and simulated spectra allowed the distribution of carbon types in Yallourn coal to be determined; the carbon aromaticity is 42%, and 30% of the carbon is present in methylene groups. The method was also used to determine structural changes during pyrolysis. At 773 K, aliphatic carbon structures are lost, but higher temperatures are necessary to decompose phenolic structures. 相似文献