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81.
Gourovitch Monica L.; Kirkby Brenda S.; Goldberg Terry E.; Weinberger Daniel R.; Gold James M.; Esposito Giuseppe; Van Horn John D.; Berman Karen Faith 《Canadian Metallurgical Quarterly》2000,14(3):353
To evaluate the functional neuroanatomies underlying letter and category fluency, 18 normal controls were studied with oxygen-15 water regional cerebral blood flow positron emission tomography. Three counterbalanced conditions each consisted of 6 trials (45 s each): letter fluency (generating words when cued with a particular letter), semantic fluency (generating words when cued with a particular category), and a control condition (generating days of the week and months of the year). Relative to the control, participants activated similar brain regions during both fluency tasks, including the anterior cingulate, left prefrontal regions, thalamus, and cerebellum; reductions were found in parietal and temporal regions. In a direct comparison of the 2 fluency tasks, inferior frontal cortex and temporoparietal cortex (hypothesized to participate in a phonologic loop for accessing word pronunciation) were activated more during letter than semantic fluency, whereas left temporal cortex (associated with access to semantic storage) was activated more during semantic than letter fluency. This study identifies subtle differences in the neural networks underlying letter and semantic fluency that may underlie the dissociation of these abilities in patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
83.
Burke M Clarke B Rochev Y Gorelov A Carroll W 《Journal of materials science. Materials in medicine》2008,19(5):1971-1979
As polymer coatings become more widely used in the biomedical device industry, both to improve biocompatibility and as coatings
for localised drug delivery, quantitative methods to measure the adhesive strength between coatings and substrates become
a very important consideration. The aim of this study was to take a method for estimating the interfacial fracture toughness
of a film to a flat substrate and apply it to Nitinol wires used in the production of medical devices. An investigation into
the affect of surface roughness on the fracture toughness was also conducted. For the present study, a thermoresponsive based
Poly (N-isopropylacrylamide) polymer was coated onto nitinol wire substrates and the adhesion strength between the polymer and wire
was measured using a nanoindentation technique. Different surface treated nitinol wires, with different surface topography
and roughness were used, and the affect of these surface properties on adhesion strength was investigated. Results showed
that it was possible to apply the delamination technique to wire samples and obtain fracture toughness values. Results also
showed that the surface roughness is an important parameter that can affect the adhesion between a coating and the substrate.
It was found that, as the average surface roughness increased so also did the adhesive strength between the coating and wire
sample. 相似文献
84.
Gonzalez MV Tang Y Phillips GJ Lloyd AW Hall B Stratford PW Lewis AL 《Journal of materials science. Materials in medicine》2008,19(2):767-775
DC Bead™ is a sulfonate-modified, PVA-based microspherical embolisation agent approved for the treatment of hypervascular
tumours and arterio-venous malformations. The beads have previously been shown to actively sequester oppositely charged drugs,
such as doxorubicin hydrochloride (dox) by an ion-exchange mechanism. In order to characterise the release kinetics and predict
the in vivo behaviour of drug eluting beads (DEB), two elution methods were utilised. The first, an application of the USP
dissolution method Type II - Apparatus, enables study of the complete elution of loaded DC Bead in less than 4 h, allowing
relatively rapid comparison to be made between different products and formulations. Release data obtained using this method
were fitted to first order kinetics (R
2 > 0.998) and the elution constants shown to increase with the total surface area of the beads exposed to the elution medium.
Diffusion coefficients were calculated adopting the Fickian diffusion model, which predicted slow elution rates under physiological
conditions. The second method involved the use of a T-Apparatus where the drug experiences an element of diffusion through
a static environment. This method was developed to resemble the in vivo situation in embolisation procedures more closely.
Slow release of dox from DC Bead with half-lives over 1,500 h were predicted for all size ranges using a slow release model.
A strong linear relationship was found between the release data from T-Apparatus and pharmacokinetic data obtained from patients
treated with DC Bead loaded with dox in transarterial chemoembolisation (TACE) procedures. These data indicated a Level A
in vitro–in vivo correlation (IVIVC) for the first 24 h post embolisation. Both systems developed were automated and good
reproducibility was obtained for all samples, demonstrating the usefulness of these elution techniques for product development
and comparative testing. 相似文献
85.
Changes in the crustacean zooplankton community composition and abundance in Lake Winnipeg (1969–2006) provide a rare opportunity to examine their response to environmental changes in the largest naturally eutrophic lake on the Canadian prairies. Since 1929, zooplankton species composition in Lake Winnipeg has changed little except for the addition of the invasive cladoceran, Eubosmina coregoni in 1994. The dominant taxa in the lake in summer include: Leptodiaptomus ashlandi, Acanthocyclops vernalis, Diacyclops thomasi, Daphnia retrocurva, Daphnia mendotae, Diaphanosoma birgei, Eubosmina coregoni, and Bosmina longirostris. Climate-accelerated nutrient loading to southern Lake Winnipeg over the last two decades has led to increased phytoplankton abundance and higher frequency of cyanobacterial blooms especially in its northern basin. Crustacean zooplankton have likewise increased especially in the North Basin, but less so in the more nutrient rich South Basin, possibly as a consequence of higher densities of pelagic planktivorous fish and light-limited primary production compared with the more transparent North basin (Brunskill et al., 1979, 1980). Calanoid copepods play a larger role in the South basin food web in contrast to cyclopoid copepods and Cladocera in the North basin. The study begins to fill the recognized gap in understanding of Lake Winnipeg's food web structure and provides a baseline for evaluating ongoing changes in the zooplankton community with the arrival of new non-indigenous taxa, e.g. Bythotrephes longimanus and Dreissena polymorpha. It reinforces previous work demonstrating that zooplankton provide valuable indices toward evaluating the health of an ecosystem. 相似文献
86.
Enzymatic modification of trilinolein: Incorporation of n-3 polyunsaturated fatty acids 总被引:2,自引:0,他引:2
Casimir C. Akoh Brenda H. Jennings Dorris A. Lillard 《Journal of the American Oil Chemists' Society》1995,72(11):1317-1321
Two immobilized lipases, IM60 fromMucor miehei and SP435 fromCandida antarctica, were used as biocatalysts for the modification of trilinolein with n-3 polyunsaturated fatty acids (PUFA), such as eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA), by using their ethyl esters as acyl donors (EEPA and EDHA, respectively). Transesterification
(ester-ester interchange) reactions were carried out in organic solvent. The products were analyzed according to their equivalent
carbon number and polarity by reverse-phase high-performance liquid chromatography, and the fatty acid profiles were determined
by gas-liquid chromatography. Modified triacylglycerol products contained 1 or 2 molecules of n-3 PUFA. With EEPA as the acyl
donor, the total EPA product yields with IM60 and SP435 as biocatalysts were 79.6 and 81.4%, respectively. However, with EDHA
as the acyl donor and IM60 and SP435 as biocatalysts, the total DHA product yields were 70.5 and 79.7%, respectively. Effects
of reaction parameters, such as type of solvent, enzyme load, time course, and molar ratio of substrates on the n-3 PUFA incorporation,
were followed with SP435 as the biocatalyst. High yields were obtained, even in the absence of organic solvent. These lipids
do hold promise for specialty nutrition and other therapeutic uses. 相似文献
87.
Prof. Alain Verbeke Ph.D. Assoc. Prof. Vernon Bachor Ph.D. Brenda Nguyen 《Management International Review》2013,53(4):535-554
- This paper empirically tests the effectiveness of information and communications technology (ICT) knowledge transfer and adoption in the multinational enterprise (MNE) as an issue of critical importance to contemporary MNE functioning. In contrast to mainstream thinking on absorptive capacity, but in line with prevailing international business theory, our research supports the proposition that perceptions of procedural justice, rather than absorptive capacity, determine effectiveness, especially in cases of high tacit knowledge transfers.
- Data was collected from senior ICT representatives in 86 Canadian subsidiaries of foreign owned MNEs. Each of these subsidiaries recently experienced a significant ICT transfer imposed by the parent organization.
- Support was found for the main propositions: Procedural justice significantly predicted successful ICT transfer and adoption, while absorptive capacity was not significant. These findings are consistent even when knowledge tacitness was high.
- The perceived success of the ICT transfer as well as its adoption varied widely across these firms. The potential reasons for this divergence in effectiveness are manifold, but our findings suggest that in situations of substantial knowledge tacitness, a higher level of procedural justice, rather than a higher level of absorptive capacity, is critical to effective transfer and adoption.
88.
Michel Bédard Shawn Marshall Malcolm Man-Son-Hing Bruce Weaver Isabelle Gélinas Nicol Korner-Bitensky Barbara Mazer Gary Naglie Michelle M. Porter Mark J. Rapoport Holly Tuokko Brenda Vrkljan 《Accident; analysis and prevention》2013
Background
A new tool, the SIMARD-MD, has been proposed to help physicians identify cognitively impaired drivers who may be unfit to drive, but little empirical evidence is available to justify its use. We analyzed data from a cohort of older Canadian drivers who had undergone cognitive testing to: (1) correlate the SIMARD-MD with other tools that measure cognition (e.g., trail-making test), (2) identify how many drivers, using published cut-offs on the SIMARD-MD, would be recommended to lose their license, or be considered fit to drive, or be required to undergo further driving assessment, and (3) determine if the SIMARD-MD is biased by level of education as many cognitive tools are.Methods
Cross-sectional data from 841 drivers aged 70 and over from seven Canadian sites who are enrolled in a 5-year cohort study were used for the analyses. Scores on the SIMARD-MD were correlated with scores on the other cognitive measures. The recommendations that would be made based on the SIMARD-MD scores were based on published cut-off values suggested by the authors of the tool. The impact of education status was examined using linear regression controlling for age.Results
Correlations between the SIMARD-MD and other cognitive measures ranged from .15 to .86. Using published cut-off scores, 21 participants (2.5%) would have been recommended to relinquish their licenses, 428 (50.9%) would have been deemed fit to drive, and 392 (46.6%) would have been required to undergo further testing. We found a difference of 8.19 points (95% CI = 4.99, 11.40, p < .001) in favor of drivers with post-secondary education versus those without, representing over 11% of the mean score.Discussion
The SIMARD-MD is unlikely to be valuable to clinicians because it lacks sufficient precision to provide clear recommendations about fitness-to-drive. Recommendations based solely on the SIMARD-MD may place many seniors at risk of losing their transportation mobility or incurring unnecessary stress and costs to prove they are safe to drive. Furthermore, the education bias may create an unwanted structural inequity. Hence, adoption of the SIMARD-MD as a tool to determine fitness-to-drive appears premature. 相似文献89.
Andrew Woolnough Danish Salim Shawn C. Marshall Kelly Weegar Michelle M. Porter Mark J. Rapoport Malcolm Man-Son-Hing Michel Bédard Isabelle Gélinas Nicol Korner-Bitensky Barbara Mazer Gary Naglie Holly Tuokko Brenda Vrkljan 《Accident; analysis and prevention》2013
Background
Chronic health conditions associated with ageing can lead to changes in driving ability. The Canadian Driving Research Initiative for Vehicular Safety in the Elderly (Candrive II) is a 5-year prospective study funded by the Canadian Institutes of Health Research aiming to develop an in-office screening tool that will help clinicians identify potentially at-risk older drivers. Currently, no tools exist to directly predict the risk of motor vehicle collision (MVC) in this population. The American Medical Association (AMA), in collaboration with the National Highway Traffic Safety Association, has designed an opinion-based guide for assessing medical fitness to drive in older adults and recommends that physicians use the Assessment of Driving Related Skills (ADReS) as a test battery to measure vision, cognition and motor/somatosensory functions related to driving. The ADReS consists of the Snellen visual acuity test, visual fields by confrontation test, Trail Making Test part B, clock drawing test, Rapid Pace Walk, and manual tests of range of motion and motor strength. We used baseline data from the Candrive/Ozcandrive common cohort of older drivers to evaluate the validity of the ADReS subtests. We hypothesized that participants who crashed in the 2 years before the baseline assessment would have poorer scores on the ADReS subtests than participants who had not crashed.Methods
In the Candrive/Ozcandrive study, 1230 participants aged 70 years or older were recruited from 7 Canadian cities, 1 Australian city and 1 New Zealand city, all of whom completed a comprehensive clinical assessment at study entry. The assessment included all tests selected as part of the ADReS. For this historical cohort study, data on all crashes (at-fault and non-at-fault) that occurred within 2 years preceding the baseline assessment were obtained from the respective licensing jurisdictions. Those who crashed were compared to those who had not crashed on their ADReS subtest scores using Pearson's chi-squared test and Student's t-test.Results
Sixty-three of the 1230 participants (5.1%) were involved in an MVC within the 2 years preceding the baseline assessment. Contrary to our hypothesis, there were no statistically significant associations between abnormal performance on the tests constituting the ADReS and history of crash in the previous 2 years (p > 0.01).Discussion
We found that a history of crash in the previous 2 years was not associated with abnormalities on the subtests comprising the ADReS. This suggests the need for prospective analyses of risk factors over time to establish sensitive, valid predictors of crash that can be incorporated in clinical practice guidelines. 相似文献90.