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511.
512.
On the application of supercritical fluid extraction to the deacidification of olive oils 总被引:1,自引:0,他引:1
M. Gonçalves A. M. P. Vasconcelos E. J. S. Gomes de Azevedo H. J. Chaves das Neves M. Nunes da Ponte 《Journal of the American Oil Chemists' Society》1991,68(7):474-480
A recent suggestion on the applicability of supercritical fluid extraction to the deacidification of olive oils of high acid
content was based on solubility data in clear disagreement with the results of other authors. In this work, we measured the
solubilities of substances chosen for their importance in that extraction process, namely pure glycerol trioleate, the most
abundant triglyceride in olive oil, and of a husk oil with a high acid content. Our results agree well with some of the previous
reports on this subject. These seem to be a trustworthy data base, but more results are needed for a definite conclusion about
the technical feasibility of the process. 相似文献
513.
A chemical method to coat submicron silica particles with nanocrystalline zinc sulfide is described. The ZnS nanocoating was obtained by the thermalysis of zinc diethyldithiocarbamate in the presence of morphologically well defined silica particles. The powders obtained were isolated and were characterized by UV/visible optical reflectance, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the silica surfaces became homogeneously coated with ZnS as the reaction time was increased. This coating consists in clusters of small ZnS particles whose dimensions are within the nanometric range. 相似文献
514.
Jandre FC Pino AV Lacorte I Neves JH Giannella-Neto A 《IEEE transactions on bio-medical engineering》2004,51(5):823-831
A closed-loop lung ventilation controller was designed, aiming to: 1) track a desired end-tidal CO2 pressure (Pet CO2), 2) find the positive end-expiratory pressure (PEEP) of minimum estimated respiratory system elastance (Ers,e), and 3) follow objective functions conjectured to reduce lung injury. After numerical simulations, tests were performed in six paralyzed piglets. Respiratory mechanics parameters were estimated by the recursive least squares (RLS) method. The controller incorporated a modified PI controller for Pet CO2 and a gradient descent method for PEEP. In each animal, three automated PEEP control runs were performed, as well as a manual PEEP titration of Ers,e and a multiple PetCO2 step change trial. Overall performance indexes were obtained from PEEP control, such as minimum Ers,e (37.0 +/- 4.5 cmH2O x L(-1)), time to reach the minimum Ers,e (235 +/- 182 s) and associated PEEP (6.5 +/- 1.0 cmH2O), and from Pet CO2 control, such as rise time (53 +/- 22 s), absolute overshoot/undershoot of PetCO2 (3 +/- 1 mmHg), and settling time (145 +/- 72 s). The resulting CO2 controller dynamics approximate physiological responses, and results from PEEP control were similar to those obtained by manual titration. Multiple dependencies linking the involved variables are discussed. The present controller can help to implement and evaluate objective functions that meet clinical goals. 相似文献
515.
Brown ME Kowalewski M Neves RJ Cherry DS Schreiber ME 《Environmental science & technology》2005,39(6):1455-1462
This study utilized freshwater mussel shells to assess mercury (Hg) contamination in the North Fork Holston River that extirpated (caused local extinctions of) a diverse mussel fauna. Shells (n = 366) were collected from five sites situated upstream (two sites), just below (one site), and downstream (two sites) of the town of Saltville, Virginia, where Hg was used to produce chlorine and caustic soda from 1950 to 1972. Shell samples were used to test the (1) utility of geochemical signatures of shells for assessing the spatial variation in Hg levels in the river relative to the contamination source and (2) value of taphonomy (post-mortem shell alteration) for distinguishing sites that differ in extirpation histories. Geochemical signatures of 40 shells, analyzed using atomic absorption spectroscopy, indicated a strong longitudinal pattern. All shells from the two upstream sites had low Hg concentrations (<5-31 microg/kg), shells directly below Saltville had variable, but dramatically higher concentrations (23-4637 microg/kg), and shells from the two downstream sites displayed intermediate Hg levels (<5-115 microg/kg) that declined with distance from Saltville. Two pre-industrial shells, collected at Saltville in 1917, yielded very low Hg estimates (5-6 microg/kg). Hg signatures were consistent among mussel species, suggesting that Hg concentrations were invariant to species type; most likely, highly variable Hg levels, both across sites and through time, overwhelmed any interspecific differences in Hg acquisition. Also, a notable postmortem incorporation of Hg in mussel shells seemed unlikely, as the Hg content was not correlated with shell taphonomy (r= 0.18; p = 0.28). The taphonomic analysis (n = 366) showed that the degree of shell alteration reliably distinguished sites with different extirpation histories. At Saltville, where live mussels have been absent for at least 30 years, shells were most heavily altered and fragmented. Conversely, fresh-looking shells abounded upstream, where reproducing mussel populations are still present. In summary, relic shells offered valuable spatio-temporal data on Hg concentrations in a polluted ecosystem, and shell taphonomic signatures discriminated sites with different extirpation histories. The shell-based strategies exemplified here do not require sampling live specimens and may augment more standard strategies applied to environmental monitoring. The approach should prove especially useful in areas with unknown extirpation and pollution histories. 相似文献
516.
The albumin and globulin fractions from lentil seeds were isolated and characterised by gel filtration. The latter was shown to be homogeneous and the former heterogeneous on PAGE. The amino acid analysis revealed high values of amidic amino acids for both fractions with great differences in the sulphur-containing amino acids. Native albumin, globulin and salt-soluble proteins were markedly resistant to trypsin hydrolysis compared to casein. The SDS-PAGE of native salt-soluble proteins indicated that the globulin fragments (20 to 30 kD) were slowly digested in the presence of albumin. The heating increased the hydrolysis of the proteins in the order: salt-soluble, albumin and globulin. The facilitated hydrolysis of the heated salt-soluble fraction seemed to be due to protein-protein interactions induced by heat. 相似文献
517.
The authors discuss a technique that offers the combination of shared bandwidth and rejection rate parameters, together with the quality of service predicted by neural networks in a novel strategy for connection admission control and call routing 相似文献
518.
519.
Eisenberger Robert; Karagonlar Gokhan; Stinglhamber Florence; Neves Pedro; Becker Thomas E.; Gonzalez-Morales M. Gloria; Steiger-Mueller Meta 《Canadian Metallurgical Quarterly》2010,95(6):1085
In order to account for wide variation in the relationship between leader–member exchange and employees' affective organizational commitment, we propose a concept termed supervisor's organizational embodiment (SOE), which involves the extent to which employees identify their supervisor with the organization. With samples of 251 social service employees in the United States (Study 1) and 346 employees in multiple Portuguese organizations (Study 2), we found that as SOE increased, the association between leader–member exchange and affective organizational commitment became greater. This interaction carried through to in-role and extra-role performance. With regard to antecedents, we found in Study 1 that supervisor's self-reported identification with the organization increased supervisor's expression of positive statements about the organization, which in turn increased subordinates' SOE. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
520.
Sylwia Czonka Eduardo Fischer Kerche Roberta Motta Neves Anna Strkowska Krzysztof Strzelec 《International journal of molecular sciences》2021,22(20)
This study aims to evaluate the influence of using a bleached Curauá fiber (CF) as filler in a novel rigid polyurethane foam (RPUF) composite. The influence of 0.1, 0.5 and 1 wt.% of the reinforcements on the processing characteristics, cellular structure, mechanical, dynamic-mechanical, thermal, and flame behaviors were assessed and discussed for RPUF freely expanded. The results showed that the use of 0.5 wt.% of CF resulted in RPUF with smoother cell structure with low differences on the processing times and viscosity for the filled pre-polyol. These morphological features were responsible for the gains in mechanical properties, in both parallel and perpendicular rise directions, and better viscoelastic characteristics. Despite the gains, higher thermal conductivity and lower flammability were reported for the developed RPUF composites, related to the high content of cellulose and hemicellulose on the bleached CF chemical composition. This work shows the possibility of using a Brazilian vegetable fiber, with low exploration for the manufacturing of composite materials with improved properties. The developed RPUF presents high applicability as enhanced cores for the manufacturing of structural sandwich panels, mainly used in civil, aircraft, and marine industries. 相似文献