全文获取类型
收费全文 | 684篇 |
免费 | 10篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 35篇 |
综合类 | 1篇 |
化学工业 | 108篇 |
金属工艺 | 42篇 |
机械仪表 | 15篇 |
建筑科学 | 6篇 |
能源动力 | 21篇 |
轻工业 | 21篇 |
无线电 | 108篇 |
一般工业技术 | 105篇 |
冶金工业 | 164篇 |
原子能技术 | 23篇 |
自动化技术 | 50篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 4篇 |
2018年 | 12篇 |
2016年 | 11篇 |
2015年 | 3篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 14篇 |
2011年 | 24篇 |
2010年 | 31篇 |
2009年 | 23篇 |
2008年 | 27篇 |
2007年 | 18篇 |
2006年 | 24篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 10篇 |
2001年 | 16篇 |
2000年 | 5篇 |
1999年 | 31篇 |
1998年 | 60篇 |
1997年 | 39篇 |
1996年 | 31篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 14篇 |
1976年 | 11篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有699条查询结果,搜索用时 15 毫秒
41.
BACKGROUND: Neutrophils contribute to the host defense mechanism, but they can cause remote organ injury in peritonitis. The purpose of this study was to examine neutrophil adhesion to the peritoneum and remote organs simultaneously in peritonitis using a fluorescence microscopic method. STUDY DESIGN: Experiment 1: Sprague-Dawley rats (n = 16) were injected intraperitoneally (ip) with saline solution or 10(5), 10(7), or 10(9) Escherichia coli. Five hours after challenge, 1 x 10(6) fluorescein-labeled neutrophils were infused. Two minutes after neutrophil injection, five peritoneal samples (the greater omentum, mesentery, parietal peritoneum, colon, and ileum), both lungs, the liver, and the right kidney were harvested for counting of labeled neutrophils under epifluorescent microscopy. Lung myeloperoxidase (MPO) activity was also determined. Experiment 2: Rats (n = 23) were given 10(9) E. coli ip. Before challenge (0 h) or at 1, 5, or 10 h after challenge, labeled neutrophils were infused. Then, the labeled neutrophil numbers in organs and lung MPO activities were assessed as described for Experiment 1. Hemodynamic and arterial blood gas data were also obtained in another set of rats before and at 1, 5, 8 and 10 h after 10(9) E. coli ip challenge. RESULTS: Experiment 1: The labeled neutrophil numbers in the peritoneum, lungs, and kidney showed significant positive correlations with the injected bacterial numbers. Lung MPO also positively correlated with E. coli number and labeled neutrophil number in the lungs. Experiment 2: Labeled neutrophil numbers in the peritoneum and kidney peaked at 5 h. The pulmonary labeled neutrophil number rose, reaching a plateau at 5 h. No remarkable change was observed in the hepatic labeled neutrophil number. There was a positive correlation between lung MPO activity and pulmonary labeled neutrophil number. Hemodynamic and blood gas data reflected a hyperdynamic state. CONCLUSIONS: Concomitant dose-dependent increases in neutrophil adhesion in the peritoneum, lungs, and kidney were observed in this peritonitis model. Increased neutrophil adhesion was transient in the peritoneum and kidney but persistent in the lungs. Strategies modulating neutrophil adhesion in organs are anticipated to be useful for the treatment of peritonitis. 相似文献
42.
43.
Metal-in-gap (MIG) heads are commonly used for high-density magnetic recording. Metal core recession and head stains increase the gap between the tape and the head, resulting in signal loss. In this study, accelerated sliding wear tests of Co-γFe2O3, and metal particle (MP) tapes against MIC heads made of three different amorphous and, nanocrystalline metals were conducted under various operating conditions. Metal core recess and propensity for head staining were measured. The degree of tape contact with a recessed core was also measured by pressing the tape against a glass slide with Cr grids and using an optical interference technique. The authors found that the core recess was about the same for all three core metals. Core recess by MP tape was larger than that, by oxide tape. The tape speed appeared to have little effect on the recess value. The authors also found that significant recess may occur during initial contouring of the head surface; however, after sliding for about 250 km, core recess reaches a steady-stale value which may be either higher or lower than the initial values. The mechanism of core recession was studied. The authors believe that core recession occurs as a consequence of the debris trapped, between the tape and the core, in addition to that caused by some tape contact. Formation of head stains was observed in all combinations. The stains fanned on the metal cores were heaviest for CoNbZr metal, followed by CoTaZr and FeTaC. Co-γFe2O3 tape produced a more severe stain than the MP tape. The apparent roughening of head rubbing surface observed for CoNbZr heads sliding against Co-γFe2O3, tape was due to the formation of stains. 相似文献
44.
M Tanaka H Yanagi C Hirano K Kobayashi S Tomura S Tsuchiya 《Canadian Metallurgical Quarterly》1997,44(9):702-712
The characteristics of elderly being cared for at home and their caregivers were analyzed based on a questionnaire about health and care for the elderly. We also assessed the problems of home care in view of activities of daily living (ADL) of the home-care recipient. Subjects were members of a health insurance union or their families and ages were more than 65 years old. Results were as follows; 1. The total number of released questionnaires was 5,472, of which responses totally 2,567 (46.9%) were received. Frequencies of the elderly at home without care, at home with care, and in hospitals or nursing home were 86.3%, 9.6% and 4.1%, respectively. 2. We categorized the home care recipient according to their ADL and analyzed their status. The frequency of using health care equipment for home care was significantly higher in the low ADL groups than in the high ADL groups. Caregivers in low ADL groups felt much more care burden than those in high ADL groups. 3. There was a tendency for differences in the use of community welfare services such as visiting nurses or short-stay between the home care recipient with dementia (group D) and the bedfast home care recipient (group C). Approximately 30% of caregivers in group D wanted to transfer the care of the elderly to hospitals or nursing home. 4. In Tokyo and nearby prefectures, there was a highly frequency that main caregivers were recipients' children. In the rural prefecture it was more frequent that the main caregiver was recipients' wife or husband only. 相似文献
45.
Zhanpeng Lu Tetsuo Shoji Yoichi Takeda Yuzuru Ito Akira Kai Nobuhisa Tsuchiya 《Corrosion Science》2008,50(3):625-638
The stress corrosion cracking (SCC) growth rates of 316L weld heat-affected zone (HAZ) and weld metal materials in high temperature pure water at 288 °C were measured using contoured double cantilever beam (CDCB) specimens and an alternating current potential drop (ACPD) in situ crack-length monitoring system. The effects of loading mode and dissolved oxygen and hydrogen on crack growth rate (CGR) were experimentally quantified. Typical intergranular SCC was found in the HAZ specimen and interdendritic SCC was identified in the weld metal specimen. The HAZ specimen and the weld metal specimen showed quite a similar response to the applied loading modes and the water chemistry, even though their absolute CGR values were different. The crack growth rates under trapezoidal loading were moderately higher than those under constant loading by several tenths percent. Switching the water chemistry from the oxygen-bearing water to the hydrogen-bearing water drastically decreased the electrochemical potential and the crack growth rate, and vice versa. A time-lag period for crack growth was observed after switching the water chemistry back to the oxygen-bearing water, where the crack growth rate was low even the dissolved oxygen concentration and the electrochemical potential had become high. Strain hardening and the resultant uneven distribution of deformation contribute to the enhanced intergranular SCC growth behavior in the HAZ area. The crack growth kinetics is analyzed based on the deformation/oxidation interaction at the crack tip, considering the importance of the electric-charge transfer, mass transport kinetics and the crack tip strain rate. 相似文献
46.
Douseki T. Shigematsu S. Yamada J. Harada M. Inokawa H. Tsuchiya T. 《Solid-State Circuits, IEEE Journal of》1997,32(10):1604-1609
This paper proposes a multithreshold CMOS (MTCMOS) circuit that uses SIMOX process technology. This MTCMOS/SIMOX circuit combines fully depleted low-threshold CMOS logic gates and partially depleted high-threshold power-switch transistors. The low-threshold CMOS gates have a large noise margin for fluctuations in operating temperature in addition to high-speed operation at the low supply voltage of 0.5 V. The high-threshold power-switch transistor in which the body is connected to the gate through the reverse-diode makes it possible to obtain large channel conductance in the active mode without any increase of the leakage current in the sleep mode. The effectiveness of the MTCMOS/SIMOX circuit is confirmed by an evaluation of a gate-chain test element group (TEG) and an experimental 0.5-V, 40-MHz, 16-b ALU, which were designed and fabricated with 0.25-μm MTCMOS/SIMOX technology 相似文献
47.
A Kano K Kambara M Arakawa F Ando M Ohno M Tsuchiya K Nishigaki H Fujiwara 《Canadian Metallurgical Quarterly》1995,79(4):1320-1329
We studied the effects of ventilation and pleural effusion on measurements of airway thermal volume (ATV) and pulmonary blood flow (PBF) by using the airway gas thermometry method of V. B. Serikov, M. S. Rumm, K. Kambara, M. I. Bootomo, A. R. Osmack, and N. C. Staub (J. Appl. Physiol. 72: 944-953, 1992) in 39 anesthetized dogs with or without lung edema or pleural effusion. To examine the differential effects of increased-pressure and increased-permeability lung edema on accuracy and sensitivity of ATV and PBF, two models of lung edema were induced by intravenous infusion of a Dextran 70 solution and alloxan monohydrate, respectively. Dogs were hyperventilated for 3 min by using a wide range of minute ventilation (VE) to produce two steady-state conditions of airway temperature. Higher levels of VE increased an estimated amount of ATV. The ATV produced by hyperventilation at VE values of 559, 158, and 72 ml.min-1.kg-1 was consistent with the gravimetric total lung mass, the blood-free wet lung weight, and the extravascular lung water volume, respectively. The coefficient of lung thermal conductivity, a practical index of the rate of heat conduction through tissue from lung vessels, was related to the ratio of the decrease in expired air temperature to VE, and estimated PBF was consistent with the thermodilution cardiac output. Pleural effusion had little effect on measurements of ATV and PBF. However, ATV and PBF showed increased variation in dogs with dextran-induced lung edema. 相似文献
48.
T Kawauchi T Sasaki K Yoshida H Matsumoto RX Chen MY Huang KS Tsuchiya T Otani 《Canadian Metallurgical Quarterly》1997,50(4):297-303
beta-(2-Hydroxyethoxy)-5 alpha-cholest-8(14)-en-15-one, a synthetic inhibitor of cholesterol biosynthesis, was shown to exhibit a high affinity to oxysterol binding protein. This was proved by ultracentrifugation of the protein fraction from rabbit liver in the presence of the 3H-labeled inhibitor, 3 beta-(2-hydroxy-2-[3H]ethoxy)-5 alpha-cholest-8(14)-en-15-one, or by the substitution of the [3H]-25-hydroxycholesterol in its complex with the oxysterol binding protein. In human hepatoma Hep G2 cells, the inhibitor decreased activity of 3-hydroxy-3-methylglutaryl CoA reductase [ID50 (2.7 +/- 0.7) x 10(-5) M] and was transformed into 3 beta-[2-(9-Z-octadecenoyloxy)ethoxy]-5 alpha-cholest-8(14)-en-15-one. 相似文献
49.
Nakahara K. Tsuchiya T. Kitatani T. Shinoda K. Kikawa T. Hamano F. Fujisaki S. Taniguchi T. Nomoto E. Sawada M. Yuasa T. 《Lightwave Technology, Journal of》2004,22(1):159-165
Direct modulation at 12.5 Gb/s of 1.3-/spl mu/m InGaAlAs distributed feedback (DFB) ridge waveguide (RWG) lasers with low-resistance notch-free gratings running up to 115/spl deg/C is experimentally demonstrated. It was achieved by the combination of the high differential gain of an InGaAlAs MQW active layer, high characteristic temperature of RWG structure, and low-resistance notch-free grating. Moreover, successful transmission of 10-Gb/s modulated signals over 30-km standard single-mode fiber was achieved with the laser running at up to 115/spl deg/C. These results confirm the suitability of this type of laser for use as the cost-effective light source in 12.5-Gb/s and 10-Gb/s datacom applications. 相似文献
50.
Influence of different fluoride containing electrolytes on the formation of self-organized titania nanotubes by Ti anodization 总被引:1,自引:0,他引:1
J. M. Macak L. V. Taveira H. Tsuchiya K. Sirotna J. Macak P. Schmuki 《Journal of Electroceramics》2006,16(1):29-34
The formation of self-organized porous titania nanotubes is achieved by electrochemical anodization under specific experimental
conditions. In present work, the formation of porous titania nanotubes on titanium substrates is investigated in several SO42−/F− based electrolytes. The presence of some non-porous layers covering the porous layers and accompanying the pore growth is
observed. We discuss in details the influence of different electrolyte composition on the structure of self-organized porous
layers, investigate the conditions for ideal pore growth. SEM investigations and XRD, AES and EDX surface analyses are carried
out to characterize the self-organized porous layers. The results show that using SO42−/F− electrolytes with different cations can drastically influence the final morphology of the self-organized porous nanotubes.
We furthermore show that the nanotubes consist of TiO2 and that they remain unchanged when annealed. 相似文献