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排序方式: 共有3135条查询结果,搜索用时 31 毫秒
61.
JP Edwards SJ West CL Pooley KB Marschke LJ Farmer TK Jones 《Canadian Metallurgical Quarterly》1998,8(7):745-750
Typhoid fever is often associated with abnormal liver biochemical tests, but severe hepatic involvement with a clinical feature of acute hepatitis is a rare complication. There have been more than 150 cases of salmonella hepatitis reported from both developed and developing countries. The documented incidence varies widely from less than 1% to 26% patients with enteric fever. The possible associated factors for development of salmonella hepatitis are virulence of the organisms, delayed treatment and poor general health of the patients. The pathogenesis of severe hepatic involvement in salmonella infection may be multifactorial and includes endotoxin, local inflammatory and/or host immune reactions. Clinical jaundice in salmonella hepatitis usually occurs within the first 2 weeks of the febrile illness. Hepatomegaly and moderate elevation of transaminase levels are common findings. Extreme hepatic dysfunction with hepatic encephalopathy is a rare coexisting complication in salmonella hepatitis. A positive culture for salmonella from blood or stool is essential to differentiate salmonella hepatitis from other causes of acute hepatitis. Hepatic pathology is characterized by the presence of typhoid nodules with marked hyperplasia of reticuloendothelial cells. The prognosis is usually good as salmonella hepatitis responds well to a specific antibiotic therapy and juandice resolves with clinical improvement. The clinical course can be severe with a mortality rate as high as 20%, particularly with delayed treatment or in patients with other complications of salmonella infection. As enteric fever is a common infection, the recognition of salmonella hepatitis is of clinical importance. 相似文献
62.
D. Candela N. Masuhara D. S. Sherrill D. O. Edwards 《Journal of Low Temperature Physics》1986,63(5-6):369-399
Standing spin-wave modes in liquid3He have been studied by cw NMR at Larmor frequencies of 1, 2, and 4 MHz and pressures of 0, 6.3, and 12.3 bar. The spin waves, which produce peaks in the NMR line, are visible at temperatures below 5 mK at zero pressure. With the assumption of a slightly simplified sample shape and no transverse spin relaxation at the walls, the theory of Leggett fits the spin-wave frequencies in the normal liquid very well, giving a value of the Fermi liquid parameterF
1
a
=–0.6±0.2 at zero pressure. The width of some of the peaks is larger than expected from other determinations of the quasiparticle diffusion time
D
. This could be due to wall relaxation or to deviations from the assumed sample geometry. In the superfluid A1 and A phases, where the data cannot be fitted to existing theories, the spin-wave modes are shifted in frequency and suffer additional damping as the temperature is decreased. At still lower temperatures in the B phase an inversion of the spin-wave spectrum from one side of the NMR line to the other is observed, agreeing quantitatively with the predictions of the 1975 theory of Combescot. 相似文献
63.
Gang Li Dan I. Enache Jennifer Edwards Albert F. Carley David W. Knight Graham J. Hutchings 《Catalysis Letters》2006,110(1-2):7-13
The oxidation of benzyl alcohol to benzaldehyde has been investigated in the absence of solvent using zeolite-supported Au
and Au–Pd catalysts. Three zeolites were investigated, ZSM-5, zeolite β and zeolite Y, and these were contrasted with the
titanoslicalite TS-1 and TiO2 as supports. For the Au catalysts the best results are obtained with zeolite β as the support and the conversions were comparable
or better than those observed with TiO2 in terms of turn over frequencies. However, the selectivities observed with the acidic zeolites were lower than the non-acidic
TS-1 and TiO2. This is due to the subsequent reaction of benzaldehyde via acid catalysed reactions to give benzyl benzoate and its dibenzyl
acetal, and, in some cases dibenzylether. Initial catalysts were evaluated with a gold loading of 2 wt% and increasing this
to 4 wt% showed the expected increase in activity, indicating that there is scope to improve the performance of these catalysts.
The most active catalysts were prepared by impregnation and catalysts prepared by deposition precipitation were considerably
less active. Introduction of Pd into the catalyst improved the activity without significantly affecting the selectivity. 相似文献
64.
G. Oladunni Taylor John J. Albers G. Russell Warnick Janet L. Adolphson H. McFariane D. R. Sullivan C. E. West V. Sri-Hari R. Edwards 《Lipids》1987,22(3):173-177
The high mortality rate from coronary heart disease (CHD) among Indians compared to Negroes in Trinidad led us to test plasma
lipid profiles to see whether dietary or genetic factors might be involved. There were no interracial differences in the composition
of plasma cholesterol ester fatty acids of the tested women and neonates. This finding suggests that dietary fat does not
account for the interracial difference in CHD, nor does the cause appear to be due to genetic differences in lipid profiles,
as there was no significant difference between values for plasma triglycerides, total cholesterol, high density lipoprotein
(HDL) cholesterol, apo-I, apo-II, apo B or cholesterol ester fatty acids in the cord blood of each racial group.
Blood samples were collected from 69 nonpregnant and 71 postpartum, fasted Negro and Indian women. Also taken were 71 umbilical
cord blood samples. The mean triglyceride level was significantly lower in the Negro nonpregnant and postpartum women than
in the Indians. HDL cholesterol and apo-I values were lower in the Indian women. There were no significant differences in
the total cholesterol and apo B measurements. The triglyceride values for postpartum women were higher than those of the nonpregnant
Negroes and Indians (75% and 47%, respectively), whereas the total cholesterol and HDL cholesterol, apo A-I and apo A-II ranged
from 9% to 29% higher in the postpartum women. Apo B was about 40% higher postpartum in both ethnic groups.
The high CHD rate of Indians in Trinidad cannot be explained by dietary factors, plasma total cholesterol or fatty acid composition.
However, the lower level of HDL cholesterol and plasma A-I could play a role in the higher CHD rate in Indians. 相似文献
65.
Jorge Garcia-Cañadas Jon Kapla Germà Garcia-Belmonte Marten O.M. Edwards 《Electrochimica acta》2004,49(5):745-752
The dynamic response of viologen-activated nanostructured titanium dioxide has been studied by means of electrical and electro-optical measurements. We show that the state of charge of the semiconductor network is the key factor mediating between the electrode potential and colouration of viologen. Theoretically, we relate the electrode potential to the statistics of occupancy of both TiO2 nanoparticles and oxidized viologen molecules attached to the surface, on the assumption of quasi-equilibrium of Fermi levels in these contacting phases. Experimentally, we determine the statistical function from steady-state measurements (electrochemical impedance spectroscopy) of the capacitance of the semiconductor film. From this understanding we explain the main features that correlate the simultaneous voltammetry and transmittance responses. Finally, the redox process of viologen is resolved separately from the TiO2 response by means of transmittance data. 相似文献
66.
The diffusion coefficients of cyclic and linear oligomeric and polymeric dimethyl siloxanes, containing number-average numbers of skeletal bonds in the range , have been measured in toluene solution at 298K. Impermeable diffusion behaviour was observed for all the siloxanes studied, in agreement with previous findings for ethylene oxide and hexamethylene oxide oligomers and polymers. The ratio of the friction coefficients for the ring (r) and linear (l) dimethyl siloxanes was found to be (within the limits of experimental error) over the whole range of molecular weights studied. Values of the expansion factor αf for the linear poly(dimethyl siloxanes) (obtained from the diffusion measurements) were found to be approximately equal to the corresponding values for αη (found previously by viscometric studies) for small values of the excluded volume parameter z; and αf was larger than αη for large z, as predicted by first-order perturbation theory. Mean-square radii of gyration 〈s2G〉 were calculated from the diffusion data for both cyclic and linear poly(dimethyl siloxanes) assuming Gaussian statistics, and found to be in good agreement with the corresponding values obtained by neutron scattering. However, the values of 〈s2G,l〉 for the short chain poly(dimethyl siloxanes) did not agree with the corresponding values of 〈s2O,l〉, calculated using the rotational isomeric state model of Flory, Crescenzi and Mark. This discrepancy is thought to arise from deviations from Gaussian behaviour, and considerably better agreement between experiment and theory was achieved by using appropriate values of a function ψl(x), which relates radii of gyration and impermeable hydrodynamic diffusion radii. 相似文献
67.
Dan I. Enache Dean Barker Jennifer K. Edwards Stuart H. Taylor David W. Knight Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):407-411
The oxidation of benzyl alcohol with molecular oxygen under solvent-free conditions has been investigated using a range of titania-supported Au–Pd alloy catalysts to examine the effect of the Au–Pd ratio on the conversion and selectivity. The catalysts have been compared at high reaction temperature (160 °C) as well as at 100 °C, to determine the effect on selectivity since at lower reaction temperature the range of by-products that are formed are limited. Under these conditions the 2.5 wt.% Au–2.5 wt.% Pd/TiO2 was found to be the most active catalyst, whereas the Au/TiO2 catalyst demonstrated the highest selectivity to benzaldehyde. Toluene, formed via either a hydrogen transfer process or an oxygen transfer process, was observed as a major by-product under these forcing conditions. 相似文献
68.
Several classes of multiple‐mode rheological constitutive equations are examined for predicting the viscoelastic flow properties of a typical polymer melt in single and double step‐strain flows. The phenomenological parameters appearing in these models have been obtained by the fitting of experimental data taken in small‐amplitude oscillatory shear and steady shear flows. The performance of the models for predicting the experimental data in the step‐strain experiments is examined in detail. Specifically, we examine whether or not mode coupling is necessary to describe the experimental behavior under step‐strain flows. Furthermore, it is demonstrated that the reversing double step‐strain experiment is a very powerful tool for testing viscoelastic constitutive equations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
69.
Peter A. Edwards Grant Striemer Dean C. Webster 《Journal of Coatings Technology and Research》2005,2(7):517-527
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins.
Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol.
The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and
cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on
the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to
determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model
amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate
functional group is more reactive than a glycidyl ether group.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献
70.
Wen-I Li Michael Perzl Joachim Heyder Robert Langer Joseph D. Brain K.-H. Englmeier Ralph W. Niven David A. Edwards 《Journal of aerosol science》1996,27(8):1269-1286
The results of numerical simulations of the aerodynamics and of solid aerosol deaggregation phenomena arising in the process of airflow through various model human oropharyngeal cavities are reported. Special attention is given to the relevance of these simulations to the inhalation of dry-powder therapeutic aerosols. Several two- and three-dimensional mouth and throat geometries (terminating just beyond the larynx) are considered. Cross-sectional area-averaged viscous stress values are numerically determined as a function of distance from the mouth opening. These values, ranging from approximately 10 to 500 dyn cm−2, are compared with estimates of Van der Waals attractive forces per unit area of particle-particle contact so as to evaluate the ability of the flowing airstream to deaggregate aerosol particles that enter the mouth in an aggregated state (held together principally by Van der Waals attractive forces). Estimates of airstream viscous stress differ markedly depending on whether the geometry is two- or three-dimensional. Quantitative differences between flow in a 90°-bend model and an oropharyngeal geometry numerically reconstructed from a cast of a human mouth and throat are especially significant in regards to the ability of the airstream to break apart particle agglomerates. For all geometries it is observed that increasingly smaller particle agglomerates may potentially be separated as the airflow rate increases from 30 to 2001 min−1. At the highest airflows, aggregated particles of diameter near to or even below 1 μm may potentially be separated by the airflow. If separation of particle agglomerates is to occur, it appears far more likely to take place in the throat than in the mouth. This is especially apparent for the more physiologically faithful oropharyngeal geometries considered. 相似文献