全文获取类型
收费全文 | 524篇 |
免费 | 14篇 |
专业分类
电工技术 | 6篇 |
综合类 | 1篇 |
化学工业 | 131篇 |
金属工艺 | 4篇 |
机械仪表 | 9篇 |
建筑科学 | 8篇 |
能源动力 | 22篇 |
轻工业 | 59篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 83篇 |
冶金工业 | 115篇 |
原子能技术 | 25篇 |
自动化技术 | 41篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 14篇 |
2013年 | 30篇 |
2012年 | 19篇 |
2011年 | 30篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 25篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 15篇 |
1998年 | 45篇 |
1997年 | 30篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1965年 | 1篇 |
1963年 | 3篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有538条查询结果,搜索用时 15 毫秒
91.
Shao-Wen Chen Shuichiro Miwa Matt Griffiths Shanbin Shi Takashi Hibiki Mamoru Ishii 《Journal of Nuclear Science and Technology》2016,53(1):34-47
Dry-out phenomena in packed beds or porous media may cause a significant digression of cooling/reaction performance in heat transfer/chemical reactor systems. One of the phenomena responsible for the dry-out in packed beds is known as the counter-current flow limitation (CCFL). In order to investigate the CCFL phenomena induced by gas–liquid two-phase flow in packed beds inside a pool, a natural circulation packed bed test facility was designed and constructed. A total of 27 experimental conditions covering various packing media sizes (sphere diameters: 3.0, 6.4 and 9.5 mm), packed bed heights (15, 35 and 50 cm) and water level heights (1.0, 1.5 and 2.0 m) were tested to examine the CCFL criteria with adiabatic air–water two-phase flow under natural circulation conditions. Both CCFL and flow reversal phenomena were observed, and the experimental data including instantaneous and time-averaged void fraction, differential pressure and superficial gas–liquid velocities were collected. The CCFL criteria were determined when periodical oscillations of void fraction and differential pressure appear. In addition, the Wallis correlation for CCFL was utilized for data analysis, and the Wallis coefficient, C, was determined experimentally from the packed bed CCFL tests. Compared to the existing data-sets in literature, the higher C values obtained in the present experiment suggest a possibly higher dry-out heat flux for natural circulation debris systems, which may be due to the water supply from both top and bottom surfaces of the packed beds. Considering the effects of bed height and hydraulic diameter of the packing media, a newly developed model for the Wallis coefficient, C, under natural circulation CCFL is presented. The present model can predict the experimental data with an averaged absolute error of ±7.9%. 相似文献
92.
Katsuyuki Tsuda Ken'ichi Tsutsumi Manabu Yaegashi Masahiro Miyajima Takashi Ishizone Akira Hirao Fumiaki Ishii Toyoji Kakuchi 《Polymer Bulletin》1998,40(6):651-658
Summary
The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M1) with styrene (M2) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M
ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r
1= 1.80 and r
2= 0.51 for 1a, r
1= 1.72 and r
2= 0.53 for 1b, and r
1= 3.17 and r
2= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition
of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C.
Received: 28 January 1998/Accepted: 5 March 1998 相似文献
93.
Tanaka Takanori; Miwa Naofumi; Kawamura Satoru; Sohma Hitoshi; Nitta Katsutoshi; Matsushima Norio 《Protein engineering, design & selection : PEDS》1999,12(5):395-405
P26olf from olfactory tissue of frog, which may be involvedin olfactory transduction or adaptation, is a Ca2+-binding proteinwith 217 amino acids. The p26olf molecule contains two homologousparts consisting of the N-terminal half with amino acids 1109and the C-terminal half with amino acids 110217. Eachhalf resembles S100 protein with about 100 amino acids and containstwo helixloophelix Ca2+-binding structural motifsknown as EF-hands: a normal EF-hand at the C-terminus and apseudo EF-hand at the N-terminus. Multiple alignment of thetwo S100-like domains of p26olf with 18 S100 proteins indicatedthat the C-terminal putative EF-hand of each domain containsa four-residue insertion when compared with the typical EF-handmotifs in the S100 protein, while the N-terminal EF-hand ishomologous to its pseudo EF-hand. We constructed a three-dimensionalmodel of the p26olf molecule based on results of the multiplealignment and NMR structures of dimeric S100B(ßß)in the Ca2+-free state. The predicted structure of the p26olfsingle polypeptide chain satisfactorily adopts a folding patternremarkably similar to dimeric S100B(ßß). Each domainof p26olf consists of a unicornate-type four-helix bundle andthey interact with each other in an antiparallel manner formingan X-type four-helix bundle between the two domains. The twoS100-like domains of p26olf are linked by a loop with no sterichindrance, suggesting that this loop might play an importantrole in the function of p26olf. The circular dichroism spectraldata support the predicted structure of p26olf and indicatethat Ca2+-dependent conformational changes occur. Since theC-terminal putative EF-hand of each domain fully keeps the helixloophelixmotif having a longer Ca2+-binding loop, regardless of the four-residueinsertion, we propose that it is a new, novel EF-hand, althoughit is unclear whether this EF-hand binds Ca2+. P26olf is a newmember of the S100 protein family. 相似文献
94.
Jianglong Pu Fumiaki Ikegami Katsuki Nishikado Eika W. Qian 《International Journal of Hydrogen Energy》2017,42(31):19733-19743
NiRu bimetallic catalysts with different amount of CeO2 loaded on the γ-Al2O3 support were prepared. The properties of catalysts were characterized by means of N2 adsorption-desorption, XRD, H2-TPR and XPS techniques. Catalytic activities for the steam reforming of acetic acid over these catalysts were investigated at the temperature range from 650 °C to 750 °C. The addition of CeO2 dramatically improved the activity and stability of the catalyst. Among these catalysts, the NiRu/10CeAl catalyst showed the highest catalytic activity as well as a good stability owing to the abundant Ce3+ on the surface of catalyst. The existence of Ce3+ promoted the formation of CO2 from CO because of the mobilizable oxygen, which was favorable for the formation of hydrogen. The coke amount and species deposited on the catalysts after the activity tests were analyzed by DTG. As expected, the NiRu/10CeAl catalyst showed the best resistance to carbon formation. The temperature stepwise steam decoking experiment of the spent catalysts was conducted to elucidate the relationship between the existence of Ce3+ and the decoking abilities of various catalysts. It was verified that the existence of Ce3+ significantly promoted the decoking abilities of the catalysts. 相似文献
95.
Matsuoka-Sakata A Tamura H Asada H Miwa I Taketani T Yamagata Y Sugino N 《Reproduction (Cambridge, England)》2006,131(2):351-360
The present study investigates changes in blood vessel stability and its regulation in the corpus luteum (CL) during pregnancy in the rat. First, blood vessel stability in the CL was evaluated during pregnancy based on vascular leakage, which was quantified by the Evans blue assay. Vascular leakage was highest on day 3, thereafter decreased until day 15 and increased again on day 21. Secondly, to study the regulation of vascular leakage, the expression of angiopoietins was examined in the CL during pregnancy. Angiopoietin-1 (Ang-1) effects maturation and stabilization of newly formed blood vessels, while Ang-2 produces the opposite effect by allowing vascular remodeling. An immunohistochemical study showed both Ang-1 and Ang-2 expression in luteal cells. mRNA and protein levels of Ang-1 were significantly higher on days 12 and 15 than those on days 3 and 21, whereas there was no significant change in Ang-2 expression. Since estradiol contributes to CL development during mid-pregnancy, we finally studied whether estradiol regulates vascular leakage and angiopoietin expression. Rats undergoing hypophysectomy and hysterectomy (hypox-hect) on day 12 were treated with estradiol until day 15. Vascular leakage was increased and Ang-1 expression was decreased by hypox-hect, and these effects were completely reversed by estradiol treatment. In conclusion, blood vessel stability in the CL is likely to be associated with CL development and CL regression, and may be regulated by angiopoietins. Estradiol contributes to blood vessel stabilization in the CL during mid-pregnancy, which is associated with an increase in Ang-1 expression. 相似文献
96.
Average adult Japanese male (JM-103 phantom) and female (JF-103 phantom) voxel (volume pixel) phantoms were newly constructed by modifying the JM and JF phantoms previously developed at Japan Atomic Energy Agency. The JM-103 and JF-103 have average characteristics with respect to organ masses and body sizes. Their tissue segmentations were based on International Commission on Radiological Protection (ICRP) Publication 103. The anatomical and dosimetric characteristics of JM-103 and JF-103 were compared with those of ICRP adult reference male (AM phantom) and female (AF phantoms) phantoms. This study discusses their anatomical and dosimetric characteristics, and applications to the dose assessment of the atomic bomb survivors. 相似文献
97.
Kato S Hokama R Okayasu H Saitoh Y Iwai K Miwa N 《Journal of nanoscience and nanotechnology》2012,12(5):4019-4027
The 'colloidal platinum' stabilized with polyvinylpyrrolidone (Pt/PVP-colloid) was dispersed in hydrogen-rich water (HW; hydrogen concentration, 0.82 ppm; oxidation-reduction potential, -583 mV) or regular water (RW; <0.01 ppm, +218 mV). And we evaluated the antioxidant activity of Pt/PVP-colloid in HW or RW on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and improvement of blood fluidity under 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress. When applied with the 0.25-0.5 ppm Pt/PVP-colloid in RW or HW, the level of DPPH radicals decreased to 77.5-59.6% or 16.1-5.6%, in contrast to the level as high as 81.3% for HW alone, respectively, as measured by an electron spin resonance method. The horse blood, which was subjected to AAPH-induced oxidative stress, was incubated for 24 hr with RW or HW, and thereafter required 13.7 sec (100%) or 5.7 sec (42.3%) for passing through the micro-channels in a rheology equipment. When treated with 0.5-1.0 ppm Pt/PVP-colloid in RW or HW, the blood passage time in the micro-channels decreased dose-dependently to 9.7-7.3 sec (71.6-53.8%) or 4.3-1.3 sec (32.8-10.3%), and the rate of micro-channels clogged with erythrocyte aggregates decreased to 23.8-21.0% or 15.8-9.8%, respectively, from 42.8% for no addition of Pt/PVP. By scanning electron microscopy, AAPH-treated erythrocytes lost intact surface morphology on the membrane together with protrusions and without hollows, being indicative of impaired transforming ability, and the rate of erythrocyte agglutination was increased to 46.2%. When treated the horse blood with HW alone significantly decreased the rate of erythrocyte agglutination to 29.6%, whereas 1.0 ppm Pt/PVP-colloid in RW or HW decreased it to 24.1% or 21.1%, respectively. Thus, DPPH-radical-scavenging and erythrocyte-protecting effects of Pt/PVP-colloid in HW were superior to those of Pt/PVP-colloid in RW or Pt/PVP-free HW. The results could be mainly attributed to the enhanced antioxidant activity of Pt/PVP in HW, which may be due to captured-hydrogen on platinum. 相似文献
98.
Kato S Kimura M Kageyama K Tanaka H Miwa N 《Journal of nanoscience and nanotechnology》2012,12(6):4472-4477
The nitroimidazole-related hypoxic radiosensitizer, pimonidazole (Pmz) was encapsulated in liposome composed of dipalmitoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol (molar ratio = 1:1:0.2; diameter = 112.9 nm), and the radiosensitization was evaluated in human melanoma cells HMV-II. Cell proliferation was examined by WST-8 assay after X-ray irradiation in the presence of liposomal Pmz or free-Pmz under hypoxic conditions. On 7th day after X-ray irradiation of 5 Gy, cell proliferation decreased more markedly in the administration of liposomal Pmz than free-Pmz at equivalent Pmz doses. Chromatin fragmentation or nuclear condensation was observed in liposomal Pmz-treated HMV-II cells. Radiosensitization was enhanced dose-dependently along with Pmz amounts of 250-2000 microM contained in liposomal Pmz. Intracellular uptake was more abundant for liposomal Pmz for 60-240 min than for free-Pmz. Thus liposomal Pmz has a potential to overcome radiation resistance in hypoxia, owing to enhanced intracellular uptake by melanoma cells. 相似文献
99.
Advenit Makaya Takuya Tamura Kenji Miwa 《Metallurgical and Materials Transactions A》2010,41(7):1646-1657
A process combining cooling slope casting and suction casting was developed to generate a semisolid structure in a Zr-based bulk metallic glass matrix composite. The melt was injected onto a cooling slope and subsequently vacuum sucked into a cylindrical copper mold placed at the end of the slope. The structure obtained for 4-mm-diameter specimens of composition Zr66.4Nb6.4Cu10.5Ni8.7Al8 consists of a dispersion of spheroidal and rosettelike bcc crystals in a glassy matrix. Various slope angles, slope lengths, and injection pressures were tested. The coarsest and most spheroidal crystal structure was obtained at short slope lengths and high injection pressures. Microstructure analysis suggests that the slope is the location of extensive crystal nucleation and possible fragmentation, while the microstructure’s morphological evolution seems to occur mainly in the mold. The semisolid structure is expected to confer improved mechanical properties and ductility to the composite material. 相似文献
100.
Silver nanowire films are promising alternatives to tin-doped indium oxide (ITO) films as transparent conductive electrodes.
In this paper, we report the use of vacuum filtration and a polydimethylsiloxane (PDMS)-assisted transfer printing technique
to fabricate silver nanowire films on both rigid and flexible substrates, bringing advantages such as the capability of patterned
transfer, the best performance among various ITO alternatives (10 Ω/sq at 85% transparency), and good adhesion to the underlying
substrate, thus eliminating the previously reported adhesion problem. In addition, our method also allows the preparation
of high quality patterned films of silver nanowires with different line widths and shapes in a matter of few minutes, making
it a scalable process. Furthermore, use of an anodized aluminum oxide (AAO) membrane in the transfer process allows annealing
of nanowire films at moderately high temperature to obtain films with extremely high conductivity and good transparency. Using
this transfer technique, we obtained silver nanowire films on a flexible polyethylene terephthalate (PET) substrate with a
transparency of 85%, a sheet resistance of 10 Ω/sq, with good mechanical flexibility. Detailed analysis revealed that the
Ag nanowire network exhibits two-dimensional percolation behavior with good agreement between experimentally observed and
theoretically predicted values of critical volume.
相似文献