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51.
Aifantis KE Shrivastava S Odegard GM 《Journal of materials science. Materials in medicine》2011,22(6):1375-1381
The mechanical properties of collagenous tissues, such as tendon and ligaments, are of particular interest as they are found
extensively in the human body. In the present study the transverse mechanical properties of collagen fibers are reported for
the first time. The elastic modulus was found to be 63 ± 4 MPa, while the viscosity was estimated to be
14 \textGPa £ h £ 56 \textGPa \texts 14\;{\text{GPa}} \le \eta \le 56\;{\text{GPa}}\;{\text{s}} . Comparison with similar data in the literature, for bulk tendon and collagen fibrils, suggests that the apparent modulus
of a network of interconnected building blocks is reduced as compared to the modulus of the individual building blocks; in
particular E
tendon < E
fiber < E
fibril; this is due to the fact that as the scale of the microstructure increases (i) slippage and sliding between the respective
building blocks (fibrils or fibers) increases, (ii) the volume fraction of the stiff collagen proteins decreases. 相似文献
52.
Silicon nanowire (SiNW) field-effect transistors (FETs) were fabricated from nanowire mats mechanically transferred from a donor growth wafer. Top- and bottom-gate FET structures were fabricated using a doped a-Si:H thin film as the source/drain (s/d) contact. With a graded doping profile for the a-Si:H s/d contacts, the off-current for the hybrid nanowire/thin-film devices was found to decrease by 3 orders of magnitude. Devices with the graded contacts had on/off ratios of ~10(5), field-effect mobility of ~50 cm(2)/(V s), and subthreshold swing of 2.5 V/decade. A 2 in. diagonal 160 × 180 pixel image sensor array was fabricated by integrating the SiNW backplane with an a-Si:H p-i-n photodiode. 相似文献
53.
Ashok Samal Author Vitae Sanjiv Bhatia Author Vitae Author Vitae David Marx Author Vitae 《Pattern recognition》2009,42(11):2502-2513
Due to the advances in imaging and storage technologies, the number and size of images continue to grow at a rapid pace. This problem is particularly acute in the case of remotely sensed imagery. The continuous stream of sensory data from satellites poses major challenges in storage and retrieval of the satellite imagery. In the mean time, the ubiquity of Internet has resulted into an ever-growing population of users searching for various forms of information. In this paper, we describe the search engine SIMR—Satellite Image Matching and Retrieval system. SIMR provides an efficient means to match remotely sensed imagery. It computes spectral and spatial attributes of the images using a hierarchical representation. A unique aspect of our approach is the coupling of second-level spatial autocorrelation with quad tree structure. The efficiency of the web-based SIMR has been evaluated using a database of images with known characteristics: cities, towns, airports, lakes, and mountains. Results show that the integrated signature can be an effective basis for accurately searching databases of satellite based imagery. 相似文献
54.
In an ongoing study, rat and human urine have been examined for the presence of malondialdehyde (MDA) derivatives as indicators
of the nature of lipid peroxidative damage caused by this compoundin vivo. MDA in urine was found to be present mainly in the form of two lysine adducts, one acetylated and the other unacetylated,
reflectingin vivo reactions with tissue proteins. Two minor metabolites were identified as adducts with the phospholipid bases serine and ethanolamine
and a third one as an adduct with the nucleic acid base guanine. The identification of an MDA adduct with deoxyguanosine (dG-MDA)
among the products of hydrolysis of rat liver DNA suggested the possible occurrence of this compound in urine. In the present
study dG-MDA was identified in rat and in human urine, and a high-performance liquid chromatographic method utilizing fluorescence
detection was developed for its estimation. The method is sensitive to 1 pmol of dG-MDA and requires a minimum of 1 mL of
rat urine or 5 mL of human urine. Its rate of excretion by five-week-old rats (28.54±2.28 nmol/kg/24 h) (mean±SEM) was higher
than that for nine-week-old rats (6.29±1.02) and much higher than that for adult humans (0.40±0.05). The results indicate
that, as reported for 8-hydroxy-deoxyguanosine, dG-MDA excretion is related to metabolic rate. Excretion of dG-MDA by the
rat, like the excretion of total MDA, declines during growth on a body weight basis at a rate similar to the decrease in resting
energy metabolism. In contrast to other MDA derivatives excreted in rat urine, vitamin E deficiency had no effect on the excretion
of dG-MDA. Together with evidence that the dG-MDA content of rat liver DNA likewise is unaffected by vitamin E depletion or
by administration of catalysts ofin vivo lipid peroxidation, these findings indicate that DNA is protected from lipid peroxidative damage, possibly through conservation
of the vitamin E associated with the lipids of the nuclear membrane. 相似文献
55.
Colloidal Gas Aphrons (CGA) are finding increasing application in wastewater processing, bioseparations, etc. This article describes effect of various operating conditions such as pH, power input, impeller location, surfactant type and its concentration and viscosity of liquid on half life of CGA generated. Further, effects of various additives like, polymer, enzyme, solvents, salt, etc. are also investigated. A procedure for predicting the drainage rate of CGA has been proposed. 相似文献
56.
We consider self-organizing data structures when the number of data accesses is unknown. We show that certain general rearrangement rules can be modified to reduce significantly the number of data moves, without affecting the asymptotic cost of a data access. As a special case, explicit formulae are given for the expected cost of a data access and the expected number of data moves for the modified move-to-front rules for linear lists and binary trees. Since a data move usually costs at least as much as a data access, the modified rule eventually leads to a savings in total cost (the sum of data accesses and moves).This research was supported in part by the National Science Foundation, Grant Number MCS 81-17364 相似文献
57.
De la Zerda A Zavaleta C Keren S Vaithilingam S Bodapati S Liu Z Levi J Smith BR Ma TJ Oralkan O Cheng Z Chen X Dai H Khuri-Yakub BT Gambhir SS 《Nature nanotechnology》2008,3(9):557-562
Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects. 相似文献
58.
Split reporter-based bioluminescence imaging is a useful strategy for studying protein-protein as well as other intracellular interactions. We have used a combinatorial strategy to identify a novel split site for firefly luciferase with improved characteristics over previously published split sites. A combination of fragments with greater absolute signal with near-zero background signals was achieved by screening 115 different combinations. The identified fragments were further characterized by using five different interacting protein partners and an intramolecular folding strategy. Cell culture studies and imaging in living mice was performed to validate the new split sites. In addition, the signal generated by the newly identified combination of fragments (Nfluc 398/ Cfluc 394) was compared with different split luciferase fragments currently in use for studying protein-protein interactions and was shown to be markedly superior with a lower self-complementation signal and equal or higher postinteraction absolute signal. This study also identified many different combinations of nonoverlapping and overlapping firefly luciferase fragments that can be used for studying different cellular events such as subcellular localization of proteins, cell-cell fusion, and evaluating cell delivery vehicles, in addition to protein-protein interactions, both in cells and small living animals. 相似文献
59.