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51.
52.
J. Harold Falls 《Nutrient Cycling in Agroecosystems》1991,28(2):239-249
The AOAC indirect, AOAC direct and EEC direct available P2O5 methods are compared by two different collaborative studies on DAP and GTSP. The collaborative studies found the AOAC direct and EEC direct available P2O5 methods to be lower than the AOAC indirect P2O5 method when the citrate insoluble P2O5 was greater than 0.3% P2O5. Results found in the Association of Florida Phosphate Chemist Check Sample Program confirmed the lower analysis.Until 1950 the primary method of analysis for available P2O5 was the AOAC indirect method. A faster method for available P2O5 was developed and adopted in the 50's by the AOAC. Diammonium phosphate from phosphate rock was not manufactured until 1959. The current fertilizer of today was not evaluated by the AOAC direct available P2O5 method because the fertilizer had not been manufactured.The current practice to use the empirical method for determining available P2O5 for plants was evaluated in the 30's, but it is still being applied to fertilizer materials of today. Several agronomic studies with current fertilizers have shown the so-called citrate insoluble P2O5 to be available to plants, which implies a new agronomic study should be evaluated for today's fertilizer to determine its availability.Based on the high cost of P2O5 production, available P2O5 methods must be equal when applied to the same fertilizer. Manufacturers of P2O5 in fertilizers cannot tolerate a 1.0% P2O5 difference between different available P2O5 methods. No one manufacturer or buyer should have an advantage over another because of the analytical method used to determine the available P2O5. If the so-called citrate insoluble P2O5 can be proved as available P2O5, the manufacturer should be able to sell that product as total available P2O5. If every regulatory agency developed their own available P2O5 method, the result would be confusion in determining the available P2O5 and inequities in the marketing of the product. The AOAC should establish methods that are equal in value for available P2O5.Quick, unofficial available P2O5 methods used to determine large volumes of fertilizer samples can be used by regulatory agencies to speed up the analyses. When deficient fertilizer samples are found by the unofficial method, the official methods should be used to determine true availability. The quick methods of questionable accuracy should be used for screening only. Regulatory agencies should operate in a posture of being fair to the consumer and manufacturer. 相似文献
53.
The cermet fuel (U3 O8 dispersed in Al) being considered for use in the Savannah River Site Reactors is thermodynamically unstable because of the potential for an exothermic metallothermic reduction reaction. This paper describes work performed to quantify the extent of reaction during powder metallurgy (P/M) processing of the U3 O8 —Al cermet fuel, and to determine the effect of partial reduction to U4 O9 on the metallothermic reduction reaction. During the fabrication of the U3 O8 —Al cermet fuel by the P/M technique, a significant portion of the U3 O8 is reduced to U4 O9 . The reaction between U4 O9 and Al is also exothermic; however, the maximum heat released by the reaction is substantially less than that released for the U3 O8 —Al reaction, approximately 335 J (80 cal) per gram of oxide reacted compared to 940 J (225 cal). Metallothermic reduction reactions for U3 O8 /U4 O9 /Al mixtures do not occur at the normal reactor operating temperature, ∼ 370 K (∼ 100°C) or at temperatures below the melting point of aluminum, 930 K (660°C). 相似文献
54.
Robert F. Smith Harold D. Pierce Jr. John H. Borden 《Journal of chemical ecology》1991,17(7):1437-1447
The first known sex pheromone for the family Miridae is reported for the mullein bug,Campylomma verbasci (Meyer) (Heteroptera: Miridae). Extracts of and Porapak Q-trapped volatiles from females were attractive to males in field bioassays. Butyl butyrate and hexyl butyrate were the predominant compounds in the females' volatiles, but these compounds previously had been found to be inactive when released alone or in combination. Butyl butyrate in combination with an isolated trace chemical, (E)-crotyl butyrate (which was inactive alone), rivaled the attraction elicited by five live females. When synthetic butyl butyrate and (E)-crotyl butyrate in a 16: 1 ratio were released at 91 or 183 g/day, they comprised an effective attractant for male bugs. 相似文献
55.
Semih Eser Robert G. Jenkins Guangquan Wei Harold H. Schobert Joseph T. Joseph 《Fuel》1991,70(12):1445-1455
High pressure microdilatometer experiments were performed on a subbituminous (Wyodak) and a bituminous (Illinois no. 6) coal in helium and hydrogen atmospheres with and without added tetralin. Wyodak coal samples showed no swelling but contractions ranging between 24 and 40 vol% upon heating at 20 and 100 °C min− 1 under helium or hydrogen pressures between 150 and 1000 psig (˜1.0–6.9 MPa). Under the same conditions, Illinois no. 6 coals displayed contractions (25–60 vol%) prior to swelling up to 117 vol%. Upon tetralin addition (at 35–190 wt% of the coal), Wyodak coal samples did not swell but showed an increasing contraction with increasing helium or hydrogen pressure due to a slight softening and fusion of the coal particles. In contrast, addition of tetralin at much lower concentrations (5–35 wt%) had a marked effect on the contraction and swelling behaviour of Illinois no. 6. A maximum swelling of 200 vol% was obtained at a tetralin addition of 30 wt%. The increased swelling results from more extensive softening and fusion of coal particles in the presence of tetralin. Both coals showed a decreasing char yield with increasing tetralin concentration. The substantially lower extent of interaction observed between Wyodak coal samples and tetralin compared to Illinois no. 6 coal can be attributed to the differences in pore structure and/or chemical constitution of the two coal samples. Examination of the resultant solids by optical microscopy revealed the microstructural changes produced by thermal treatment in dilatometer experiments. 相似文献
56.
It has previously been determined that (13S,9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid was mainly converted into (13S,9Z,11E)-13-hydroxy-9,11-octadecadienoic acid by 5 N KHO with preservation of the stereochemistry of the reactant [Simpson, T.D.,
and Gardner, H.W. (1993)Lipids 28, 325–330]. In addition, about 20–25% of the reactant was converted into several unknown by-products. In the present work
it was confirmed that the stereochemistry was conserved during the hydroperoxy-diene to hydroxydiene transformation, but also,
novel by-products were identified. It was found that after only 40 min reaction (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid accumulated to as much as 7% of the total. Later, (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid began to disappear, and several other compounds continued to increase in yield. Two of these
compounds, 2-butyl-3,5-tetradecadienedioic acid and 2-butyl-4-hydroxy-5-tetradecenedioic acid, were shown to originate from
(9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid, and they accumulated up to 2–3% each after 4 to 6 h. Some other lesser products included
11-hydroxy-9,12-heptadecadienoic acid, 3-hydroxy-4-tridecenedioic acid, 13-oxo-9,11-octadecadienoic acid and 12,13-epoxy-11-hydroxy-9-octadecenoic
acid. Except for the latter two, most or all of the compounds could have originated from Favorskii rearrangement of the early
product, (9Z)-13-oxo-trans-11,12-epoxy-9-octadecenoic acid, through a cyclopropanone intermediate. 相似文献
57.
The energy interaction curves of a number of diatomic and polyatomic dication systems were calculated in order to study their energy-trapping properties. Generally, the ab initio complete active space multiconfiguration self-consistent field method was used in an extended valence + polarization basis set, with compact effective potentials replacing the core electrons. The diatomic dications include all ten possible binary combinations of oxygen, sulphur, selenium, and tellurium. O22+ shows the largest exothermicity, measured from equilibrium to the monocation combination asymptote, and highest barrier to dissociation. The calculated equilibrium bond length and harmonic vibrational frequency agree very well with experiment. The O22+, SO2+, SeO2+, and TeO2+ series show progressively decreasing exothermicities but similar barrier heights. The non-oxides, in contrast, show similar exothermicities but decreasing barriers with increasing size of the atom constituents. These trends are interpreted in terms of both valence bond curve-crossing and molecular orbital bonding models. The ozone dication, O32+, is found to have a number of low-lying singlet and triplet stationary state structures spanning near-linear to D3h2+ symmetries. Although the calculated exothermicity is even larger than for O22+, the barrier to O2+ + O+ dissociation is predicted to be low in each case. O22+ surrounded by six argon atoms to model an isolating environment shows increased equilibrium O–O bond length, decreased exothermicity, and increased barrier to dissociation, relative to the bare dication. O22+ flanked at each end by a perpendicularly oriented H2 molecule in a staggered conformation is obstructed from direct conversion to the water dimer dication by a high barrier. However, [(H2O)2]2+ dissociates smoothly from equilibrium to two water monocations with a large exothermicity but a small barrier. 相似文献
58.
Ten samples of mineral-matter residue were obtained by the radio-frequency low-temperature ashing of subbituminous and bituminous coals. The low-temperature ash samples were then heated progressively from 400 °C to 1400 °C at 100 °C intervals. Mineral phases present at each temperature interval were determined by X-ray diffraction analyses. The minerals originally present in the coals (quartz, kaolinite, illite, pyrite, calcite, gypsum, dolomite, and sphalerite) were all altered to higher temperature phases. Several of these phases, including kaolinite, metakaolinite, mullite, anhydrite, and anorthite, were found only in limited temperature ranges. Therefore the temperature of formation of the ashes in which they occur may be determined. Mineralogical differences were observed between coal samples from the Rocky Mountain Province, the Illinois Basin, and the Appalachians; and as a result of these mineralogical differences, different high-temperature phases resulted as the samples were heated. However, regional generalizations cannot be made until a greater number of samples have been studied. 相似文献
59.
Harold H. Taylor F. E. Luddy J. W. Hampson H. L. Rothbart 《Journal of the American Oil Chemists' Society》1976,53(7):491-495
The United States is the most important beef tallow producer in the world, supplying ca. 5.5 billion pounds annually. Approximately
half of this beef tallow is exported at relatively low prices when compared to other fats and oils. Only ca. 10% of the total
is used in domestic edible products. On the other hand, cocoa butter, coconut oil, palm oil, and palmkernel oil are imported
oils whose demand for use in food and confectionery products has been increasing over the past few years. The first of these
is the most expensive fat in the world. Beef tallow contains specific triglycerides which are also contained in these imported
fats and oils. Through modern technology, beef tallow has been fractionated into products which are compatible with or superior
to the imported fats and oils. It is visualized that products from fractionated beef tallow can be used as substitutes and
extenders to cocoa butter, palm oil, and other fats and oils in the food and confectionery industries. The economic evaluation
in this paper, analyzed through time series data and multiple regression techniques, established the past relationships between
per capita consumption of confectionery food fat, beef tallow, cocoa butter, adjusted per capita disposable income, and adjusted
costs of confectionery, beef tallow, and cocoa butter from 1956 to 1973. The substitutability of fats and oils was evaluated
and the potential uses of fractionated beef tallow investigated.
Presented in part at the AOCS meeting in Cincinnati, September 1975. 相似文献
60.
Beta brass single crystal, bicrystal and tricrystal stress strain behavior were determined for a series of isoaxial specimens
in which the bicrystals and tricrystals were incompatible in shear along the grain boundary. Volume fractions of grain boundary
deformation were also determined to ascertain the effect of increased constraint on grain boundary strengthening. It was found
that bicrystal flow stress was considerably higher than single crystal flow stress and that tricrystal strain hardening was
only slightly larger than that of the bicrystal. For the tricrystals the grain boundary deformation zone is larger than that
of corresponding bicrystals because of both configurational and constraint effects. This larger zone indicates that secondary
stresses extend further from the boundary in tricrystals than in bicrystals. It was concluded that despite increased constraint,
, the average grain boundary stress for the tricrystals, is smaller than that for corresponding bicrystals and that because
of the increased extent of the secondary stress,σ
b
i, the stress in the center component away from the grain boundary, is higher than that of the single crystal at corresponding
strains. The relationship of these observations to corresponding stresses in polycrystalline material is examined.
where Taek Dong Lee was formerly a Graduate Student.
This paper is based on a thesis to be submitted by Taek Dong Lee in partial fulfillment of the requirements for the degree
of Doctor of Philosophy at Polytechnic Institute of New York. 相似文献