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71.
Tae-Hyun Kim Jin-Goo Kang Jeong-Soo Sohn Kang-In Rhee Seoung-Won Lee Shun-Myung Shin 《Metals and Materials International》2008,14(5):655-658
The treatment of spent zinc-carbon batteries for the recovery of valuable metals followed by conversion to Mn−Zn ferrite has
been conducted employing two-stage alkali and acid leaching and co-precipitation method. In the first stage, leaching process
was carried out with 4 M NaOH, which resulted in a recovery of 63.4 %Zn and 0.1% Mn. Electrowinning of alkali leaching solution
containing 12.75 g/L Zn at a current density of 0.2 A/cm2 produced Zn metal of 15 nm to 30 nm size and 99.9% purity. The second stage leaching of residue with 3 M H2SO4 and 6 vol.% H2O2 at a solid/liquid ratio of 1∶10 indicated the leaching efficiency of 98.0% Zn, 97.9% Mn and 55.2% Fe. The obtained leaching
solution was finally adjusted to suitable mole ratios of Mn∶Zn∶Fe (1∶1∶4) by the addition of Zn and Fe sulfate salts followed
by pH control to produce Mn−Zn ferrite powder. The characterization of the ferrite powder showed uniform nano-crystalline
particles of about 20 nm size with spinel structure. 相似文献
72.
Sung-Chan Kim Baek-Seok Ko Tae-Jong Baek Byeong-Ok Lim An D. Dong-Hoon Shin Jin-Koo Rhee 《Microwave and Wireless Components Letters, IEEE》2005,15(10):652-654
The hybrid ring coupler was designed and fabricated on a GaAs substrate using surface micromachining techniques, which adopted dielectric-supported air-gapped microstrip line (DAML) structure. The fabrication process of DAML is compatible with the standard monolithic microwave integrated circuit (MMIC) techniques, and the hybrid ring coupler can be simply integrated into a plane-structural MMIC. The fabricated hybrid ring coupler shows wideband characteristics of the coupling loss of 3.57 /spl plusmn/ 0.22dB and the transmission loss of 3.80 /spl plusmn/ 0.08dB across the measured frequency range of 85 to 105GHz. The isolation characteristics and output phase differences are -34dB and 180/spl plusmn/1/spl deg/, at 94GHz, respectively. 相似文献
73.
S. Nourbakhsh O. Sahin W. H. Rhee H. Margolin 《Metallurgical and Materials Transactions A》1991,22(12):3059-3064
A pressure-cast NiAl composite reinforced with polycrystalline alumina (PRD-166) fibers containing 0.2 weight fraction of
partially stabilized zirconia was examined by optical and transmission electron microscopy (TEM). Fibers in the preform used
for casting were forced into contact, and fiber bonding occurred in a number of instances. Fiber volume fraction was increased
from an initial value of 0.4 to 0.6 as a consequence of the applied pressure. An explanation is offered for the interaction
of applied pressure, wetting angle, and the rigidity of the fiber preform on the final volume fraction of the fibers in the
composite. At the fiber/matrix interface, the alumina was free of zirconia particles. It is proposed that alumina grain growth
forced the zirconia into the molten NiAl, where it dissolved. As solidification took place, the concentration of zirconium
in the molten NiAl increased to a point where zirconium reacted with alumina to form zirconia again. 相似文献
74.
Vivek Chidambaram Eric Phua Jian Rong Gan Chee Lip Rhee Min Woo Daniel 《Journal of Electronic Materials》2013,42(9):2803-2812
Cyanate ester resin-based composite materials have been proposed as potential encapsulants for high-temperature applications. The objective of this study is to develop a cyanate ester-based encapsulant, which can also serve as a flip-chip underfill as well as for traditional encapsulation. Two different materials, quartz and alumina fillers, have been studied. The impact of shapes and sizes of the fillers on the overall thermomechanical properties has been investigated. The adhesion strengths of the materials to the ceramic substrate, Kovar lid, and silicon die have also been characterized. The modulus of the resin and the shape of the fillers play a pivotal role in minimizing thermal stress, generated by coefficient of thermal expansion mismatches. Smaller filler particles were found to have better adhesion to the cyanate ester resin. The high-temperature performance of the cyanate ester-based encapsulants was evaluated by thermal aging at 300°C for up to 500 h. 相似文献
75.
Wireless technologies are gaining increased acceptance as a viable technology within the industrial solution space. However, it is important for control system architects to fully understand not only the benefits but also the challenges and limitations of wireless technologies. The complex interrelationships between the various wireless technology characteristics require careful tradeoffs to be made in the design of the solution. This is especially true for applications that need to handle continuous data streams where high capacity is critical to maintain the scalability and reliability of the network. Although still relatively new, mesh networks have proven themselves to have significant advantages in robustness, scalability, and low-power consumption over other wireless technologies for use in industrial monitoring applications. Mesh networks employing PDR address the scalability challenges of wireless sensor networking that can limit implementation in production situations by significantly increasing overall packet-delivery rate and reducing network communication overhead. HC_WSN, an approach that will emerge as the important next trend in the wireless sensor networking industry, can be implemented in addition to PDR techniques and will further support the increasing number of applications that require the wireless sensor network to handle greater amounts of data. 相似文献
76.
H Kook JH Rhee SE Lee SY Kang SS Chung KW Cho YH Baik 《Canadian Metallurgical Quarterly》1999,365(2-3):267-272
Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s). 相似文献
77.
Edible oxygen barrier bilayer film pouches from corn zein and soy protein isolate for olive oil packaging 总被引:1,自引:0,他引:1
An edible oxygen barrier film pouch was fabricated from a heat sealable corn zein (CZ) layer laminated on soy protein isolate (SPI) film and used to package olive oil condiments for use with instant noodles. The mechanical, barrier, and physical properties of the CZ/SPI bilayer films were then investigated and the oxidative stability of olive oil in the pouches was measured during storage under dry and intermediate relative humidity conditions. When compared to the SPI film, lamination with an additional layer of CZ film led to increased tensile strength and water barrier properties, while it had a lower elongation at break and decreased oxygen barrier properties. Nevertheless, the oxygen permeability of the CZ/SPI film (0.81 × 10−18 m3 m/m2 s Pa) was lower than that of nylon-metalocene catalyzed linear low-density polyethylene (NY/mLLDPE) film (3.51 × 10−18 m3 m/m2 s Pa) which is the material usually used for such condiments. The CZ/SPI bilayer films generated here were heat sealable at 120-130 °C and produced a seal strength greater than 300 N/m. The higher oxygen barrier property of the CZ/SPI bilayer films resulted in reduced oxidative rancidity of olive oil packaged in the CZ/SPI film when compared to olive oil packaged in NY/mLLDPE films. 相似文献
78.
Dong‐Seon Won Jin‐Hyang Kim Hyo Jin No You Jin Cho Ju‐Yeon Lee Bum Ku Rhee Hee‐Dok Choi 《Polymer International》2010,59(2):162-168
Stabilization of electrically induced dipole alignment is one of the important criteria in the development of nonlinear optical (NLO) polymers for electro‐optic device applications. Polyurethanes for NLO applications have attracted attention because of their high thermal stability due to hydrogen bonding. In the work reported here, we designed and synthesized a new type of NLO polyurethane, in which the pendant NLO chromophores are part of the polymer backbone. This mid‐type NLO polymer is expected to have the merits of both main‐chain and side‐chain NLO polymers, namely stable dipole alignment and good solubility. 1‐[3,4‐Di‐(2‐hydroxyethoxy)phenyl]‐2‐(2‐thienyl)ethene was prepared and condensed with 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate to yield a polyurethane. This polyurethane was reacted with tetracyanoethylene to give a novel Y‐type polyurethane (7) containing 1‐(3,4‐dioxyphenyl)‐2‐[5‐(1,2,2‐tricyanovinyl)‐2‐thienyl]ethenes as NLO chromophores, which constitute part of the polymer backbone. Polyurethane 7 is soluble in common organic solvents such as N,N‐dimethylformamide and dimethylsulfoxide. It shows a thermal stability up to 280 °C from thermogravimetric analysis with a glass transition temperature obtained from differential scanning calorimetry of ca 162 °C. The second harmonic generation (SHG) coefficient (d33) of a poled polymer film of he polyurethane at 1560 nm fundamental wavelength is ca 1.11 × 10?18 C. Polymer 7 exhibits an enhanced thermal stability and no significant SHG decay is observed below 150 °C, which is acceptable for NLO device applications. Copyright © 2009 Society of Chemical Industry 相似文献
79.
Se-Ra Won Deug-Chan Lee Seuk Hyun Ko Jang-Won Kim Hae-Ik Rhee 《Food research international (Ottawa, Ont.)》2008,41(10):952-956
The major proteins in honey have different molecular weights depending upon the honeybee species. To confirm the origin of major honey proteins, honey protein produced by Apis cerana or Apis mellifera were purified and analyzed by MALDI-TOF. Two major proteins were identified as a major royal jelly protein 1. Although two major proteins shared primary structure, they showed different molecular weights of 56 and 59 kDa, respectively. To discriminate the honeybee species producing honey using SDS–PAGE, artificial marker proteins, 56 and 59 kDa, were produced from Escherichia coli. Two artificial marker proteins were co-electrophoresed with honey samples and the difference in molecular weight was readily distinguished by SDS–PAGE. Therefore, the measurement of major proteins in honey is a useful method to discriminate the honey that produced from different honeybee species. 相似文献
80.
M. R. Geller D. J. Thouless S. W. Rhee W. F. Vinen 《Journal of Low Temperature Physics》2000,121(5-6):411-416
It has been known since the pioneering work of Onsager and Feynman that the statistical mechanics and dynamics of vortices play an essential role in the behavior of superfluids and superconductors. However, the theory of vortices in quantum fluids remains in a most unsatisfactory state, with many conflicting results in the literature. In this paper we review the theory of Thouless, Ao and Niu, which gives an expression for the total transverse force acting on a quantized vortex that is in apparent disagreement with the word of lordanskii and of Lifshitz and Pitaevskii. In particular, no transverse force proportional to the asymptotic normal fluid velocity was found. We use two-fluid hydrodynamics to study this discrepancy. 相似文献