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排序方式: 共有373条查询结果,搜索用时 828 毫秒
81.
Muthu Vignesh Vellayappan Arunpandian Balaji Aruna Priyadarshini Subramanian Agnes Aruna John Saravana Kumar Jaganathan Selvakumar Murugesan Hemanth Mohandas Eko Supriyanto Mustafa Yusof 《Science and Technology of Advanced Materials》2015,16(3)
Cardiovascular disease claims millions of lives every year throughout the world. Biomaterials are used widely for the treatment of this fatal disease. With the advent of nanotechnology, the use of nanocomposites has become almost inevitable in the field of biomaterials. The versatile properties of nanocomposites, such as improved durability and biocompatibility, make them an ideal choice for various biomedical applications. Among the various nanocomposites, polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane, bacterial cellulose with polyvinyl alcohol, carbon nanotubes, graphene oxide and nano-hydroxyapatite nanocomposites have gained popularity as putative choices for biomaterials in cardiovascular applications owing to their superior properties. In this review, various studies performed utilizing these nanocomposites for improving the mechanical strength, anti-calcification potential and hemocompatibility of heart valves are reviewed and summarized. The primary motive of this work is to shed light on the emerging nanocomposites for heart valve applications. Furthermore, we aim to promote the prospects of these nanocomposites in the campaign against cardiovascular diseases. 相似文献
82.
An extra 30–40 million tonnes of food fish will be required by 2050 to meet the increasing need for a growing population. In the wake of plateauing of the traditional food fish supplies from marine capture fisheries, the gap in the supplies will have to be met from aquaculture and other plausible strategies, including increased inland fish production. The existing fisheries in tropical reservoirs and lakes traditionally tend to target only table-sized fish, often exotics and/or translocated species, using a single type of gear, mostly gill nets. In such fisheries, many small indigenous species (SIS) are unexploited due to the prohibition of the use of suitable fishing gear. The status of fisheries for small, indigenous species of four Sri Lankan reservoirs was investigated with a view to identifying regulatory constraints to the establishment of SIS fisheries without adversely impacting existing commercial fisheries. It is estimated that a potential of 7.5 t per fisher per annum of SIS through the introduction of a new fishery is obtainable. This study is significant as SIS are recognized as important sources of essential macro- and micronutrients which can play a crucial role in combating malnutrition and micronutrient deficiencies in rural populations of many South and Southeast Asian countries. 相似文献
83.
This research presents schemes for automated visual inspection for boundary defects and classification using neural networks. An efficient method for representing circular boundaries is proposed utilizing a curvature and circular fitting algorithm. For classification, two types of neural network modelling schemes are established. First, a multi-layer perceptron is discussed for defect classification problems. Second, a Hopfield network is modelled to be used for continuous-type variables by a minimizing energy function. Extensive tests are conducted on the casting parts, then the results of neural networks are compared with those of traditional pattern classifiers. 相似文献
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86.
Aruna Kumar Mohanty Anindita Ghosh Pravin Sawai Kapil Pareek Susanta Banerjee Amit Das Petra Pötschke Gert Heinrich Brigitte Voit 《Polymer Engineering and Science》2014,54(11):2560-2570
Multiwalled carbon nanotube (MWCNT) filled poly(ether sulfone) (PES) and poly(ether imide) (PEI) composites were prepared with different MWCNT weight fractions (0.5–5wt%) by a solution mixing technique. Their electrical conductivities, electromagnetic interference (EMI), shielding effectiveness (SE), return loss (RL), and absorption loss (AL) were investigated. Morphologies of the fracture surfaces of nanocomposites studied by scanning electron and transmission electron microscopy showed relatively good MWCNT dispersion and distribution. The electrical conductivity of compression molded samples measured at room temperature indicated that the electrical percolation network was achieved already at 0.5% loading. The measurements of shielding effectiveness (SE) carried out in the frequency range of 8 to 12 GHz (X‐band range) showed that SE increases with measurement frequency and with filler loading, whereby no significant differences could be observed between PES and PEI as matrices. The nanocomposites based on both matrices with 5 wt% loading of MWCNT exhibited shielding levels at 8 GHz between 42 and 45 dB in comparison with the pure polymers which showed value in the range of 1 to 2 dB. RL and AL showed significantly lower values for the composites as compared to unfilled polymers, but no systematic trends were observed on frequency. POLYM. ENG. SCI., 54:2560–2570, 2014. © 2013 Society of Plastics Engineers 相似文献
87.
Aruna B. Wijeratne Jose Gracia Samuel H. Yang Peter Kroll Daniel W. Armstrong Kevin A. Schug 《Inorganic chemistry communications》2010,13(12):1504-1508
Theoretical calculations (density functional theory and ab initio (MP2)) and nuclear magnetic resonance experiments reveal a new metal-oxygen-bridged isomeric form for antimony(III)-l-tartrate that co-exists in solution and in the gas phase with its crystallographically-determined structure. 相似文献
88.
The photopolymerization of multifunctional acrylate monomers synthesized from castor oil was investigated by photo-DSC. These studies revealed that the extent of photopolymerization depended on the double bond concentration and a greater degree of crosslinking occurred in monomer mixtures with higher difunctional content. The monomer mixtures displayed significantly higher maximum rate of polymerization (Rpmax) and shorter time to reach peak maximum than the pure monomers. DMTA studies of films showed good storage modulus and broad tan δ transitions indicating heterogeneity in the crosslinked networks. The films displayed sub-Tg transitions in the loss modulus curves were possibly due to the side chain motions of the monomer acrylates which increased with increasing triacrylate concentration. Glass transition temperature (Tg) of these networks depended on composition and shifted to higher values with increasing amount of triacrylate. 相似文献
89.
In reactions centered at phosphorus, whether chemical or biochemical, a pentacoordinate transition state species or an intermediate or a stable molecule is very often encountered. In this Account, recent developments in this important area are discussed and compared with the earlier literature. Particular reference, with results from our laboratory, will be made to the apicophilicity, fluxional behavior, bond parameters, and tetra- vs pentacoordination. It is shown that the familiar apicophilicity rules give an oversimplified picture as demonstrated by several exceptions. Extremities of the P-O or P-N bond distances in PX(4)N and PO(4)N systems as revealed by a database search and possible future directions in this area are also discussed. 相似文献
90.
Geetha Baskar S. Venkatesan Aruna Dhathathreyan A. B. Mandal 《Journal of the American Oil Chemists' Society》1999,76(7):853-858
Methoxy ethyl oleate, a nonionic surfactant, has been investigated at the air/water interface for various surface properties by employing the Langmuir film balance technique. The ester forms an expanded isotherm at the air/water interface. The minimum area of packing (A 0), initial area of increase of surface pressure (A i ), collapse pressure (π c ), and area/molecule at collapse pressure (A c ) have been estimated from the isotherm curve.The higher compressibility coefficient (K) suggests that the ester forms a more expanded liquid film than the parent oleic acid. Besides, the ester film is fairly stable as suggested by only about 30% loss in area over a period of 20 min. The relaxation rates of the ester film at different surface pressures of 10, 15, and 20 mN·m?1 have been estimated from changes in the surface area/molecule with time. Interestingly, the surface area (54.2 Å2/molecule) that corresponds to a minimized structure projected for the ester, calculated theoretically, agrees reasonably well with the experimental value (57.2 Å2/molecule). 相似文献