全文获取类型
收费全文 | 407篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 92篇 |
金属工艺 | 1篇 |
机械仪表 | 9篇 |
建筑科学 | 14篇 |
能源动力 | 27篇 |
轻工业 | 37篇 |
石油天然气 | 1篇 |
无线电 | 45篇 |
一般工业技术 | 52篇 |
冶金工业 | 91篇 |
原子能技术 | 4篇 |
自动化技术 | 40篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 26篇 |
2012年 | 11篇 |
2011年 | 22篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 17篇 |
2007年 | 15篇 |
2006年 | 19篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 23篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 33篇 |
1997年 | 17篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 16篇 |
1992年 | 5篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有417条查询结果,搜索用时 15 毫秒
351.
Transition metal catalysts widely used in refineries are provided as oxides and require pre-reduction to become activated. The auto-reduction of a NiO/Al2O3 catalyst with acetic acid (HAc) followed by HAc steam reforming was investigated in a packed bed reactor. Effects of temperature and molar steam to carbon ratio (S/C) on reduction kinetics and catalyst performance were analysed. Results showed that a steady steam reforming regime along with complete NiO reduction could be obtained after a coexistence stage of reduction and reforming. A 2D nucleation and nuclei growth model fitted the NiO auto-reduction. The maximum reduction rate constant was attained at S/C = 2. Steam reforming activity of the auto-reduced catalyst was just below that of the H2-reduced catalyst, probably attributed to denser carbon filament formation and larger loss of active Ni. Despite this, a H2 yield of 76.4% of the equilibrium value and HAc conversion of 88.97% were achieved at 750 °C and S/C = 3. 相似文献
352.
G. Nagaraju K. Manjunath T. N. Ravishankar B. S. Ravikumar H. Nagabhushan G. Ebeling J. Dupont 《Journal of Materials Science》2013,48(24):8420-8426
Anatase TiO2 nanoparticles have been successfully synthesized at 130 °C for 2 days via ionic liquid-assisted hydrothermal method. The obtained products are characterized using various techniques. The X-ray diffraction data reveal that the nanoparticles are anatase TiO2. FTIR spectrum shows that the presence of ionic liquid and indicates Ti–O–Ti peak at around 398 cm?1, and the bands at 1500 and 1600 cm?1 indicates C–H in-plane vibrations and stretching of imidazolium ring. Raman spectroscopy show bands at 142, 393, 513, and 636 cm?1 reveal crystalline anatase phase. UV–Vis spectroscopy shows the λ max at 355 nm corresponding to a band gap of 3.49 eV. TEM images reveal that the average diameters of anatase TiO2 nanoparticles are in the range 50–100 nm. Anatase TiO2 exhibited excellent photocatalysis for the degradation of organic dye. 相似文献
353.
Generating annotated behavior models from end-user scenarios 总被引:2,自引:0,他引:2
354.
GA Orban P Dupont B De Bruyn R Vandenberghe A Rosier L Mortelmans 《Canadian Metallurgical Quarterly》1998,122(1):9-22
This study examined the ionic mechanism of ibutilide, a class III antiarrhythmic in clinical use, on freshly isolated human atrial cells. Cells had resting potentials of -71.4 +/- 2.4 mV, action potentials with overshoot of 36.8 +/- 1.8 mV, duration of 265 +/- 89 msec at 90% repolarization and slow repolarization (n = 16). Ibutilide, at 10(-7) M, markedly increased action potential duration. Four types of outward currents were detected: Ito, Iso, a delayed rectifier and IK1. Ibutilide had no inhibitory effect on these outward currents at 10(-7) M (n = 28). In K(+)-free solutions and -40 mV holding potential, mean peak inward current at 20 mV was -1478 +/- 103 pA (n = 12). Ibutilide increased this current to -2347 +/- 75 pA at 10(-7) M, with half maximal effect (Kd) of 0.1 to 0.9 nM between -10 and +40 mV (n = 21). At similar concentrations, the drug increased APD, with Kd of 0.7 and 0.23 nM at 70 and 90% repolarization, respectively (n = 8). Ibutilide shifted the mid-point of the steady-state inactivation curve from -21 to -12.2 mV (n = 6), and reduced current decline during repetitive depolarization (n = 5). The drug induced inward current was carried by Na+o through a nifedipine inhibited inward channel because Na+o removal eliminated the effect, and nifedipine abolished the inward current and the drug induced APD prolongation. We propose that a Na+ current through the L-type Ca++ channel mediates ibutilide's potent clinical class III antiarrhythmic action. 相似文献
355.
The aim of this article was to study the instrumental measurement of whiteness related specifically to structured textiles. Both brightened and unbrightened white textiles have been investigated. A method of controlling the acceptability of whites is proposed specifically for highly structured textiles. 相似文献
356.
J. Mall gol G. Bennett P. J. McDonald J. L. Keddie O. Dupont 《The Journal of Adhesion》2006,82(3):217-238
Tackifying resins (TR) are often used to improve the adhesive properties of waterborne pressure-sensitive adhesives (PSAs) derived from latex dispersions. There is a large gap in the understanding of how, and to what extent, the film formation mechanism of PSAs is altered by the addition of TR. Herein, magnetic resonance profiling experiments show that the addition of TR to an acrylic latex creates a coalesced surface layer or “skin” that traps water beneath it. Atomic force microscopy of the PSA surfaces supports this conclusion. In the absence of the TR, particles at the surface do not coalesce but are separated by a second phase composed of surfactant and other species with low molecular weight. The function of the TR is complex. According to dynamic mechanical analysis, the TR increases the glass transition temperature of the polymer and decreases its molecular mobility at high frequencies. On the other hand, the TR increases the molecular mobility at lower frequencies and thereby promotes the interdiffusion of latex particles to create a skin layer. In turn, the skin layer is a barrier that prevents the exudation of surfactant to the surface. The TR probably enhances the coalescence of the latex particles by increasing the compatibility between the acrylic copolymer and the solids in the serum phase. 相似文献
357.
BACKGROUND/AIMS: Animal studies have shown that the induction of cytochrome P4502E1 (CYP2E1) modulates oxidative damage induced by ethanol. Since CYP2E1 activity varies substantially in humans, we have investigated whether differences in CYP2E1 activity might influence the formation of hydroxyethyl free radicals and the stimulation of lipid peroxidation among alcohol abusers. METHODS: Chlorzoxazone oxidation, an index of CYP2E1 activity, and the levels of antibodies reacting with hydroxyethyl radical and malonyldialdehyde protein adducts were investigated in 51 alcoholic patients. RESULTS: We observed that in 40 out of 51 (78%) alcoholics, chlorzoxazone oxidation was increased over the control levels, consistently with CYP2E1 induction by ethanol. However, in the remaining 22% of the patients, in spite of a similar alcohol intake, chlorzoxazone oxidation was within the control range, indicating a lack of CYP2E1 inducibility. IgG reacting with hydroxyethyl free radical-protein adducts were absent in subjects without CYP2E1 induction, while they were significantly increased in alcoholics with induced CYP2E1 activity. IgG against malonyldialdehyde protein-adducts were increased in all patients, irrespective of CYP2E1 inducibility. Moreover, chlorzoxazone oxidation was significantly lower in alcoholics without clinical and biochemical signs of liver disease as compared to patients with alcoholic liver disease. CONCLUSIONS: These results indicate that CYP2E1 activity greatly influences the formation of hydroxyethyl radicals in humans, and suggest a possible role of CYP2E1 in the development of alcoholic liver disease. 相似文献
358.
N Jabado JL Casanova E Haddad F Dulieu JC Fournet B Dupont A Fischer C Hennequin S Blanche 《Canadian Metallurgical Quarterly》1998,27(6):1437-1441
The aim of this study was to investigate of the relationship of ovarian stromal volume, measured using three-dimensional ultrasound, to serum androgen concentrations in patients with polycystic ovaries. Serum gonadotrophin, oestradiol and androgen concentrations and ovarian volume measurements were obtained in the early follicular phase from 100 women undergoing assisted conception treatment cycles. Group 1 contained 50 women with regular menstrual cycles and normal ovarian morphology, group 2 contained 24 women with regular menstrual cycles and polycystic ovaries seen on ultrasound scan and group 3 contained 26 women with polycystic ovary syndrome. Statistical analysis included analysis of variance, Scheffé's procedure and Pearson's correlation. Total ovarian volume (15.7-16.1 versus 11 ml, P < 0.05), stromal volume (14.5 versus 9.4 ml, P < 0.05) and thecal steroid concentrations were significantly greater in groups 2 and 3. Stromal volume was positively correlated with serum androstenedione concentrations (r = 0.45, P = 0.0019 in group 3) but was not correlated with any other endocrine parameter. It was concluded that polycystic ovaries are characterized by increased ovarian stroma with associated overproduction of theca-derived steroids, particularly androstenedione. 相似文献
359.
Round-robin analysis of the RILEM TC 162-TDF beam-bending test: Part 2—Approximation of δ from the CMOD response 总被引:1,自引:0,他引:1
B. I. G. Barr M. M. Lee E. J. de Place Hansen D. Dupont E. Erdem S. Schaerlaekens B. Schnütgen H. Stang L. Vandewalle 《Materials and Structures》2003,36(9):621-630
A round robin test programme was carried out using the beam-bending test recommended by RILEM TC 162-TDF [1]. The test programme included both plain and steel fibre reinforced concrete (SFRC) beams. A detailed analysis was carried out to investigate the influence of different test configurations on measurements of the crack mouth opening displacement (CMOD). Linear elastic fracture mechanics (LEFM) and non-linear fracture mechanics (NLFM) methods were utilised to investigate the problem analytically. From the analytical studies carried out, it is proposed that the CMOD should not be measured at a distance more than 5mm from the bottom fibre of the beam. A larger distance than 5mm will cause the deviation between the measured CMOD and the true CMOD to reach an unacceptable level. A simple rigid body model has been proposed to relate the CMOD to the mid-span deflection. The NLFM analysis and experimental results were compared for both the plain and SFRC beam results and it was found that results based on the basis of CMOD can be compared to those based on deflections, for practical purposes, using the simple rigid body model. The experimental results strongly suggest that the rigid body model could be effectively applied for all the types of materials tested in the round robin test programme. In addition it was found that the conversion from CMOD to the equivalent mid-span deflection, δc, revealed good agreement between the load-average mid-span deflection (P-δ) curve and the load-equivalent mid-span deflection (P-δ) curve especially for the SFRC specimens. It is proposed that the load-CMOD (P-CMOD) curve be used to calculate the proposed RILEM design parameters (as opposed to the P-δ curve) via the use of a correction factor determined using the simple rigid body model. 相似文献
360.
N Kalach PH Benhamou F Briet J Raymond C Dupont 《Canadian Metallurgical Quarterly》1998,5(12):1359-1365
Helicobacter pylori gastric infection in children is a public health problem. Classical diagnostic tools such as endoscopy are excessively invasive in the usual clinical context. Serology at this age has multiple drawbacks. The urea-13C breath test seems today the most appropriate alternative method. The principle of the test relies upon the indirect detection of H pylori through its high urease activity. The test uses a stable (ie, non radioactive) isotope, which allows its repeated use. The main indications are the detection and the follow-up of H pylori infection. 相似文献