全文获取类型
收费全文 | 1022篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 267篇 |
金属工艺 | 30篇 |
机械仪表 | 63篇 |
建筑科学 | 10篇 |
能源动力 | 33篇 |
轻工业 | 99篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 140篇 |
一般工业技术 | 175篇 |
冶金工业 | 141篇 |
原子能技术 | 12篇 |
自动化技术 | 70篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 26篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 34篇 |
2013年 | 42篇 |
2012年 | 45篇 |
2011年 | 50篇 |
2010年 | 45篇 |
2009年 | 45篇 |
2008年 | 47篇 |
2007年 | 41篇 |
2006年 | 23篇 |
2005年 | 33篇 |
2004年 | 43篇 |
2003年 | 44篇 |
2002年 | 46篇 |
2001年 | 30篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 52篇 |
1997年 | 28篇 |
1996年 | 35篇 |
1995年 | 28篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1971年 | 2篇 |
1970年 | 4篇 |
排序方式: 共有1048条查询结果,搜索用时 19 毫秒
61.
Untersuchung der gemeinsamen Einflüsse von Nickel und Silizium sowie Chrom und Silizium auf die chemischen Aktivitäten von Kohlenstoff und Sauerstoff im flüssigen Eisen bei 1600°C unter Kohlenmonoxid-Kohlendioxid-Atmosfhäre. Zeichnerische Darstellung der Versuchsergebnisse. Vergleich mit Wirkungsparametern der Randsysteme. 相似文献
62.
J. T. Lawhon K. C. Rhee E. W. Lusas 《Journal of the American Oil Chemists' Society》1981,58(3):377-384
The production of food ingredients from undefatted soybeans by aqueous processing and isolation of protein from soy flour
by ultrafiltration membranes has been demonstrated adequately during the past decade. These relatively new techniques offer
significant advantages over conventional soy processing methods. Aqueous processing requires no petroleum-based solvent and
consequently provides increased safety and flexibility of operation (because start-up and shutdown are safe and easy). It
also provides opportunities for removal or deactivation of undesirable constituents of raw materials with appropriate water-soluble
chemicals. It is, however, less efficient in oil extraction, and demulsification is required to recover clear oil when emulsions
form. Ultrafiltration processes recover protein directly from soy flour extracts and thereby avoid generation of the whey
which results from the conventional isoelectric precipitation. These processes have the advantages of increased isolate yield
(as whey proteins are recovered in the isolate), and produce products having enhanced functionality and nitrogen solubility.
The two processing techniques have subsequently been combined to obtain a single procedure with the advantages of each. Extracts
from undefatted soybeans have been membrane processed with and without separating the oil to produce a variety of new soy
protein ingredients. 相似文献
63.
Asymptotic solutions to countercurrent moving-bed exchange equations are discussed considering the effect of axial dispersion and interphase mass transfer. Existence conditions are derived by using perturbation theory in a properly defined moving coordinate system. The flow are ratio turns out to be a very important parameter and its effect on the exchange performance is carefully examined. In particular, the effect of interphase mass transfer disappears when the exchange zone becomes stationary. Applications are illustrated by using the Langmuir adsorption isotherm. Numerical solutions of the transient equations show that the asymptotic solution may be useful. 相似文献
64.
Physicochemical characterization of diclofenac sodium-loaded poloxamer gel as a rectal delivery system with fast absorption 总被引:1,自引:0,他引:1
Yong CS Sah H Jahng Y Chang HW Son JK Lee SH Jeong TC Rhee JD Baek SH Kim CK Choi HG 《Drug development and industrial pharmacy》2003,29(5):545-553
Rectal poloxamer gel systems composed of poloxamers and bioadhesive polymers were easy to administer to the anus and were mucoadhesive to the rectal tissues without leakage after the dose. However, a poloxamer gel containing diclofenac sodium could not be developed using bioadhesive polymers, since the drug was precipitated in this preparation. To develop a poloxamer gel using sodium chloride instead of bioadhesive polymers, the physicochemical properties such as gelation temperature, gel strength, and bioadhesive force of various formulations composed of diclofenac sodium, poloxamers, and sodium chloride were investigated. Furthermore, the pharmacokinetic study of diclofenac sodium delivered by the poloxamer gel was performed. Diclofenac sodium significantly increased the gelation temperature and weakened the gel strength and bioadhesive force, while sodium chloride did the opposite. The poloxamer gels with less than 1.0% sodium chloride, in which the drug was not precipitated, were inserted into the rectum without difficulty and leakage, and were retained in the rectum of rats for at least 6 hr. Furthermore, poloxamer gel gave significantly higher initial plasma concentrations and faster Tmax of diclofenac sodium than did solid suppository, indicating that drug from poloxamer gel could be absorbed faster than that from the solid one in rats. Our results suggested that a rectal poloxamer gel system with sodium chloride and poloxamers was a more physically stable, convenient, and effective rectal dosage form for diclofenac sodium. 相似文献
65.
A transient, 3-D solution to the heat conduction equation with a small square heat source on an adiabatic surface and Newtonian convection on the opposite side was obtained using Green's functions. The geometry conservatively models conduction spreading resistance encountered by small, concentrated heat sources such as light-emitting diodes and integrated circuits in general, mounted to larger substrates such as the base of a heat sink experiencing Newtonian convection. The solution is presented for a range of nondimensional parameters. Superposition techniques can also be used to extend the applicability of the current solution to the temperature prediction of arbitrary heat flux patterns in certain cases. This technique only holds for applications where the heat transfer coefficient is not a function of temperature, such as thermal management strategies designed to rely on forced convection with air. 相似文献
66.
Pramod K. Singh B. Bhattacharya R.K. Nagarale Kang-Wook Kim Hee-Woo Rhee 《Synthetic Metals》2010,160(1-2):139-142
Biopolymer composite membranes based on chitosan doped with an ionic liquid (IL) 1-ethyl 3-methylimidazolium thiocyanate (EMImSCN) have been developed and characterized. The doped ionic liquid films show remarkable enhancement in ionic conductivity (σ). The Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and X-ray diffraction studies (XRD) affirmed the composite nature, good incorporation of ionic liquid and reduction in crystallinity of films, respectively. The interaction between ionic liquid, chitosan and iodide polymer electrolyte matrix was evaluated by cyclic voltammetry. The fabricated dye sensitized solar cell (DSSC) using this new biopolymer electrolyte membranes shows promising performance. 相似文献
67.
Seung Yong Cho Jin Won Lee Chul Rhee 《International Journal of Food Science & Technology》2010,45(5):1042-1049
Deep‐fried instant noodles were cooked in a microwave oven at 557 W (medium power) and 657 W (full power). The microwave cooking times were determined based on textural parameters and the qualities of microwave oven cooked noodles at medium power and full power were compared with those of products cooked using a conventional gas stove for 9.1 min (CON). Heating in the microwave increased the temperature of the noodle block faster than the cooking water, led to an increased degree of gelatinisation of instant noodles, and reduced the cooking times to 8.5 min (medium power) and to 7.5 min (full power). Cooking in the medium power microwave resulted in high water absorption and weak hardness values. Cooking in the full power microwave resulted in higher hardness and tensile strength than the medium power microwave and sensory evaluated organoleptic scores were comparable to the CON, despite having a significantly higher rancidity. 相似文献
68.
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
69.
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
70.
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