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排序方式: 共有98条查询结果,搜索用时 31 毫秒
1.
Chakraborty Biplab Ketan Bhuyan M. K. MacDorman Karl F. 《Multimedia Tools and Applications》2021,80(16):24319-24341
Multimedia Tools and Applications - Many vision-based human-computer interaction (HCI) applications require skin detection. However, their performance relies on accuracy in detecting skin regions... 相似文献
2.
Joshi A Qian X Dione DP Bulsara KR Breuer CK Sinusas AJ Papademetris X 《IEEE transactions on visualization and computer graphics》2008,14(6):1603-1610
The effective visualization of vascular structures is critical for diagnosis, surgical planning as well as treatment evaluation. In recent work, we have developed an algorithm for vessel detection that examines the intensity profile around each voxel in an angiographic image and determines the likelihood that any given voxel belongs to a vessel; we term this the "vesselness coefficient" of the voxel. Our results show that our algorithm works particularly well for visualizing branch points in vessels. Compared to standard Hessian based techniques, which are fine-tuned to identify long cylindrical structures, our technique identifies branches and connections with other vessels. Using our computed vesselness coefficient, we explore a set of techniques for visualizing vasculature. Visualizing vessels is particularly challenging because not only is their position in space important for clinicians but it is also important to be able to resolve their spatial relationship. We applied visualization techniques that provide shape cues as well as depth cues to allow the viewer to differentiate between vessels that are closer from those that are farther. We use our computed vesselness coefficient to effectively visualize vasculature in both clinical neurovascular x-ray computed tomography based angiography images, as well as images from three different animal studies. We conducted a formal user evaluation of our visualization techniques with the help of radiologists, surgeons, and other expert users. Results indicate that experts preferred distance color blending and tone shading for conveying depth over standard visualization techniques. 相似文献
3.
Ketan P. Detroja Ravindra D. Gudi Sachin C. Patwardhan 《Control Engineering Practice》2012,20(10):1033-1041
Historical data based fault diagnosis methods exploit two key strengths of multivariate statistical approaches, viz.: (i) data compression ability, and (ii) discriminatory ability. It has been shown that correspondence analysis (CA) is superior to principal components analysis (PCA) on both these counts (Detroja, Gudi, Patwardhan, & Roy, 2006a), and hence is more suited for the task of fault detection and isolation (FDI). In this paper, we propose a CA based methodology for fault diagnosis that can facilitate significant data reduction as well as better discrimination. The proposed methodology is based on the principle of distributional equivalence (PDE). The PDE is a property unique to the CA algorithm and can be very useful in analyzing large datasets. The principle, when applied to historical data sets for FDI, can significantly reduce the data matrix size without significantly affecting the discriminatory ability of the CA algorithm. This can significantly reduce computational load during statistical model building. The data reduction ability of the proposed methodology is demonstrated using a simulation case study involving benchmark quadruple tank laboratory process. The proposed methodology when applied to experimental data obtained from the quadruple tank process also demonstrated data reduction capabilities of the principle of distributional equivalence. The above aspect has also been validated for large-scale data sets using the benchmark Tennessee Eastman process simulation case study. 相似文献
4.
A new inorganic–organic POM-based hybrid material comprising Keggin type mono manganese substituted phosphotungstate and enantiopure S-(+)-sec-butyl amine was synthesized in an aqueous media by simple ligand substitution method. The synthesized hybrid material was systematically characterized in solid as well as solution by various physicochemical techniques such as elemental analysis, TGA, UV–vis, FT-IR, ESR and multinuclear solution NMR (31P, 1H, 13C). The presence of chirality in the synthesized material was confirmed by CD spectroscopy and polarimeter. The above study reveals the attachment of S-(+)-sec-butyl amine to Keggin type mono manganese substituted phosphotungstate through N → Mn bond. It also indicates the retainment of Keggin unit and presence of chirality in the synthesized material. An attempt was made to use the synthesized material as a heterogeneous catalyst for carrying out aerobic asymmetric oxidation of styrene using molecular oxygen. The catalyst shows the potential of being used as a stable recyclable catalytic material after simple regeneration without significant loss in conversion. 相似文献
5.
6.
Lopez-Espinosa MJ Fletcher T Armstrong B Genser B Dhatariya K Mondal D Ducatman A Leonardi G 《Environmental science & technology》2011,45(19):8160-8166
Animal studies suggest that perfluorocarbons (PFCs) may alter sexual maturation. Relationships of human PFC exposure with puberty are not clear. We conducted a cross-sectional study to investigate whether perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were associated with indicators of sexual maturation in a 2005-2006 survey of residents with PFOA water contamination from the Mid-Ohio Valley. Participants were 3076 boys and 2931 girls aged 8-18 years. They were classified as having reached puberty based on either hormone levels (total >50 ng/dL and free >5 pg/mL testosterone in boys and estradiol >20 pg/mL in girls) or onset of menarche. We estimated the odds of having reached puberty classified by these criteria and the fitted median age of reaching puberty in relation to serum PFOA and PFOS concentrations measured when puberty status was assigned. For boys, there was a relationship of reduced odds of reached puberty (raised testosterone) with increasing PFOS (delay of 190 days between the highest and lowest quartile). For girls, higher concentrations of PFOA or PFOS were associated with reduced odds of postmenarche (130 and 138 days of delay, respectively). In conclusion, our study showed a later age of puberty in this population correlated with PFC concentrations. 相似文献
7.
Δ9-tetrahydrocannabinol (THC) and merthiolate have been utilized as lysophospholipid acyltransferase inhibitors in metabolic
studies. However, their effects on acyltransferases other than lysophosphatidylcholine:acyl-CoA acyltransferase (LPCAT) are
not known. We have therefore investigated the effectiveness of THC and merthiolate in inhibiting the acylation of lysophosphatidylcholine,
lysophosphatidylethanolamine, lysophosphatidylserine, lysophosphatidylinositol (LPI) and lysophosphatidic acid (LPA) in guinea
pig liver microsomes using oleoyl-CoA and arachidonoyl-CoA as acyl donors. THC inhibited LPCAT and lysophosphatidylethanolamine:
acyl-CoA acyltransferase (LPEAT) by 40–50%, but had no effect or only slightly increased the activities of the other acyltransferases
when assayed with oleoyl-CoA as the acyl donor. The results obtained with arachidonoyl-CoA were similar to those with oleoyl-CoA,
with the exception of a 40% inhibition of lysophosphatidylserine:acyl-CoA acyltransferase (LPSAT) at concentrations of 50
μM or higher. At similar concentrations, merthiolate was more effective than THC in inhibiting the acyltransferases examined.
Selective effects on the acyltransferases were observed at low concentrations of merthiolate (20 μM or less). Thus, LPCAT
was most susceptible, followed by LPI acyltransferases, LPSAT, LPEAT and lysophosphatidic acid:acyl-CoA acyltransferases (LPAAT).
The presence of LPA did not affect the inhibition of LPCAT by merthiolate. Thus the resilience of LPAAT to merthiolate inhibition
was not due to chelation of the compound by the acidic lysolipid. Thiol reagents includingN-ethylmaleiamide, 5,5′-dithio-bis-nitrobenzoic acid, iodoacetate, β-mercaptoethanol and dithiothreitol had little or no effect on the acyltransferases relative
to equimolar concentrations of merthiolate. The above results indicate that merthiolate is a much more effective inhibitor
of lysophospholipid:acyl-CoA acyltransferases than is THC, and that the selectivity exhibited by merthiolate may be due to
direct and specific interaction with the acyltransferases. 相似文献
8.
Ketan Pancholi Nassim Ahras Eleanor Stride Mohan Edirisinghe 《Journal of materials science. Materials in medicine》2009,20(4):917-923
Uniform spherical chitosan particles of size <10 μm in diameter are important in drug delivery applications due to their excellent
biocompability and biodegradability. A high concentration of chitosan in the particles can help to control the release of
drugs and methods for processing high viscosity chitosan solutions are therefore required. In principle, any type of polymer,
whether hydrophobic or hydrophilic, can be electrosprayed to obtain monodisperse particles of diameter <10 μm. In practice,
however, electrospraying of biopolymers having viscosities of >100 mPa s results in particles >10 μm diameter. In this study,
by reducing surface tension of a high viscosity chitosan suspension, it was found that smaller diameter particles could be
prepared. Chitosan solutions were electrosprayed in the stable cone-jet mode to systematically study the relationship between
particle diameter, viscosity and surface tension. Increasing viscosity resulted in larger diameter particles with a broad
size distribution, but decreasing surface tension had the opposite effect. Results show that a chitosan solution having a
viscosity of ~80 mPa s can be used to prepare chitosan particles of diameter ~2.5 μm which on drying reduced to particles
of 500 nm. 相似文献
9.
Analysis‐preserving video microscopy compression via correlation and mathematical morphology 下载免费PDF全文
Chong Shao Alfred Zhong Jeremy Cribb Lukas D. Osborne E. Timothy O'Brien III Richard Superfine Ketan Mayer‐Patel Russell M. Taylor II 《Microscopy research and technique》2015,78(12):1055-1061
The large amount video data produced by multi‐channel, high‐resolution microscopy system drives the need for a new high‐performance domain‐specific video compression technique. We describe a novel compression method for video microscopy data. The method is based on Pearson's correlation and mathematical morphology. The method makes use of the point‐spread function (PSF) in the microscopy video acquisition phase. We compare our method to other lossless compression methods and to lossy JPEG, JPEG2000, and H.264 compression for various kinds of video microscopy data including fluorescence video and brightfield video. We find that for certain data sets, the new method compresses much better than lossless compression with no impact on analysis results. It achieved a best compressed size of 0.77% of the original size, 25× smaller than the best lossless technique (which yields 20% for the same video). The compressed size scales with the video's scientific data content. Further testing showed that existing lossy algorithms greatly impacted data analysis at similar compression sizes. Microsc. Res. Tech. 78:1055–1061, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
10.
Production of protein and volatile fatty acids by anaerobic digestion of blackstrap molasses was investigated. This protein
may have potential as a feed for animals (and, we hope, for humans) in the near future. Volatile fatty acids can be further
fermented to produce methane. Fermentation of molasses byEubacterium ruminantium was studied in a chemostat at a constant temperature of 37 C. This study focused on kinetics of growth of the pure culture.
The maximum rate of protein production of about 0.326 g/l/hr was obtained when the pH and retention times were 6.2 and between
5 and 7 hrs, respectively. Average cell yield was 12.6% and carbohydrate conversion was 82 to 99%. Volatile fatty acids also
were produced, with acetic acid and n-butyric acid being the predominant products. Two different kinetic models were used
to fit the experimental data. The kinetic parameters obtained for the Monod model were: μmax=0.207 (1/hr); ks=0.165 g/l. 相似文献