全文获取类型
收费全文 | 886篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 38篇 |
化学工业 | 130篇 |
金属工艺 | 18篇 |
机械仪表 | 19篇 |
建筑科学 | 12篇 |
能源动力 | 15篇 |
轻工业 | 96篇 |
无线电 | 93篇 |
一般工业技术 | 167篇 |
冶金工业 | 261篇 |
原子能技术 | 12篇 |
自动化技术 | 47篇 |
出版年
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 17篇 |
2013年 | 33篇 |
2012年 | 21篇 |
2011年 | 41篇 |
2010年 | 24篇 |
2009年 | 36篇 |
2008年 | 34篇 |
2007年 | 25篇 |
2006年 | 19篇 |
2005年 | 25篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 32篇 |
1998年 | 87篇 |
1997年 | 73篇 |
1996年 | 47篇 |
1995年 | 33篇 |
1994年 | 23篇 |
1993年 | 26篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1977年 | 9篇 |
1976年 | 15篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有908条查询结果,搜索用时 40 毫秒
91.
H Kambara M Kinoshita M Nakagawa T Sakurai C Kawai 《Canadian Metallurgical Quarterly》1995,25(2):55-61
Clinical indicators and the incidence of sudden death among 1,000 consecutive patients (816 males and 184 females) with myocardial infarction were investigated between 1983 and 1987 after coronary arteriography. Twenty-four patients died suddenly during a study period of 3.3 +/- 2.0 yrs. The yearly incidence of sudden death calculated by the Kaplan-Meier method was 0.7%, nearly half of the incidence of cardiac death (1.5%/yr). Univariate analysis demonstrated statistically significant differences in the number of cases with coronary thrombolysis in the acute phase, degree of coronary artery stenosis, the frequency and degree of congestive heart failure and angina in the acute and chronic phase, the presence of serious post-infarction arrhythmia, ejection fraction, recurrent myocardial infarction, and administration of digitalis and diuretics. between the sudden-death group and the cardiac and other patient groups. There was also a tendency to higher frequency of history of diabetes mellitus, presence of acute mitral regurgitation, nitrates and nicorandil treatment, and coronary artery bypass graft in the sudden-death group. Multivariate analysis revealed that digitalis and nitrates treatment and left anterior descending artery involvement were major contributing factors. Re-infarction, left ventricular ejection fraction, and nicorandil therapy were not significant and minor contributing factors. The incidence of sudden death increased with digitalis therapy (Odds' ratio of 9.59), and left anterior descending artery disease, and decreased with nitrates (0.34). 相似文献
92.
Yoshino K. Yin X.H. Tada K. Kawai T. Hamaguchi M. Araki H. Sugimoto R. Uchikawa N. Asanuma T. Kawahigashi M. Kato H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1996,3(3):331-344
Novel properties of recently developed conducting and insulating polymers and their composites are discussed. Properties of conducting polymer whose main chains are composed of unsaturated π-bonds depend strongly on the main chain structure, substituent and also molecular dopants. Various applications of conducting polymers such as electroluminescence (EL) elements, electrolyte capacitors, photoconductors, photovoltaic cells, superconductors and insulators at cryogenic temperature, are discussed by taking effects of molecular dopants such as C60 into consideration. A new type of insulating polymer, syndiotactic polypropylene prepared by newly developed metallocene catalysts has been studied and found to exhibit much superior electrical, thermal and mechanical characteristics compared with those of conventional isotactic polypropylene, atactic polypropylene and polyethylene. These excellent characteristics originate from lower crystallinity, smaller spherulites and different crystal lattice than in isotactic polypropylene. Negligible degradation of syndiotactic polypropylene by contact with copper is interpreted in terms of difference of catalysts and suppression of diffusion of copper cation. New types of conducting polymer, insulating polymer composites were prepared. Their conductivity was controlled over more than 10 orders of magnitude by small amounts of a conducting polymer, polypyrrole, which can be interpreted in terms of the percolation model depending on the shape and density of polypyrrole coated insulating polymer particles. Nonlinear current-voltage characteristics were also studied 相似文献
93.
For lightweight and compact implementation of a generation set, many attempts have been made by some researchers to develop a brushless self-excited synchronous generator without an ac exciter. A previous paper proposed a novel self-excitation scheme by which the second-space harmonic component of armature mmf is used for exciting the rotor field system. In this excitation scheme the effect of the series excitation characteristic, as well as a self-excited and brushless implementation without an ac exciter is automatically obtained. However, in the case of system configuration of the generator already reported, voltage regulation in the inductive load condition was very large. To remove this problem, this paper presents a new system configuration of the generator with a self-regulating feature that can compensate voltage regulation automatically. The new generator consists of a stator installing two three-phase windings, externally connected to a load and a capacitor bank, respectively, and a rotor with field and harmonic windings. In this paper the system configuration and theoretical concepts of the presented generator are described and detailed experimental investigations with a laboratory machine are also shown. 相似文献
94.
Young-Geun Park Teruo Kanki Hea-Yeon Lee Hidekazu Tanaka Tomoji Kawai 《Solid-state electronics》2003,47(12):2221
We investigated a photoconductor(PC)/ferroelectric oxide(OF)/semiconductor oxide(SO) POS-FET structure photomemory consisting of organic photoconductor CuPc/inorganic ferroelectric PbZr0.2Ti0.8O3 heterojunction gate and a ferromagnetic oxide semiconductor La0.87Ba0.13MnO3 channel. Visible light information detected by photoconductor CuPc can be memorized in ferroelectric PbZr0.2Ti0.8O3, and non-volatile and non-destructive reading out process of light information memorized in this ferroelectric layer were achieved by reading out the resistance modulation of ferromagnetic semiconductor oxide La0.87Ba0.13MnO3 channel under the photoconductor/ferroelectric gate. 相似文献
95.
A 3 dB gain-reduction bandwidth up to 65 nm (1549-1614 nm) is achieved using a two-stage erbium-doped fibre amplifier, together with an intermediate equaliser and Raman amplification in the transmission fibre 相似文献
96.
The effects of the GABAergic pathway on the dynamic range of the light response of cone-driven horizontal cells (HCs) in the carp retina were investigated using conventional intracellular recordings and computer simulations. The amplitude of the HC responses to repetitive test flashes was altered by background illumination in control Ringer's solution, but was not changed following the application of picrotoxin or bicuculline, which suggests that GABAA receptors mediate the subsequent change in light response. This phenomenon was simulated by introducing the desensitization mechanism of the GABAA receptor into a cone-HC network model. These results suggest that desensitization of the GABAA receptor shifts the dynamic range of the HCs due to light and dark adaptation. 相似文献
97.
Ulex europaeus agglutinin I (UEA I) binding was studied in 83 patients with various neuromuscular disorders. UEA I labelled endomysial capillaries and endothelial cells of perimysial blood vessels in all the examined muscles. There was no UEA I binding to muscle fibres except for all (9) cases of distal myopathy with rimmed vacuole formation (DMRV), 1 of 5 cases of inclusion body myositis and 1 of 36 cases of inflammatory myopathies. The UEA I binding was completely eliminated by preincubation of UEA I solution with L-fucose. Using electron microscopy, the UEA I binding was localized to sarcolemma and intrasarco-plasmic membranous organelles other than mitochondria. Myosatellite cells were not labelled. These findings revealed the existence of fucosylated proteins or lipids in a subset of skeletal muscles suffering from DMRV. Biochemical identification of the fucosylated substance and further detailed study on subcellular localization of UEA I binding may yield important clues to the unknown pathogenesis of DMRV. 相似文献
98.
Tamon Ozaki Noriyuki Ito Shuhei Nakamura Jiro Kawai 《Electrical Engineering in Japan》2003,144(1):12-20
The capacitance C and dielectric dissipation factor tan δ of a water‐treed XLPE sheet sample have been measured under the application of 100 V or 1 kV at 60 Hz. The values of C and tan δ at 1 kV are much larger than those at 100 V. The value of tan δ gradually decreases with the length of exposure to a voltage of 1 kV. On the other hand, C is almost constant versus the exposure time. The results have been discussed on the basis of a model in which filling of channels interconnecting voids by water is taken into account. It has been found that the increase of C and tan δ is caused by the growth of the water‐filled channel region on the application of voltage. The gradual decrease in tan δ with the exposure time is explained by the change in the conductivity of the water‐filled channel region, as a result of which the relaxation time shifts to higher frequencies. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(1): 12–20, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10160 相似文献
99.
S Nishikawa T Sonoki T Kasahara T Obi S Kubota S Kawai N Morohoshi Y Katayama 《Canadian Metallurgical Quarterly》1998,64(3):836-842
A growing body of evidence supports the existence of a tissue-based renin-angiotensin system (RAS) in the vasculature, but the functional capacity of vascular RAS was not investigated in humans. In 28 normotensive healthy control subjects, the metabolism of angiotensins through vascular tissue was investigated in normal, low, and high sodium diets by the measurement of arterial-venous gradient of endogenous angiotensin (Ang) I and Ang II in two different vascular beds (forearm and leg), combined with the study of 125I-Ang I and 125I-Ang II kinetics. In normal sodium diet subjects, forearm vascular tissue extracted 36+/-6% of 125I-Ang I and 30+/-5% of 125I-Ang II and added 14.9+/-5.1 fmol x 100 mL(-1) x min(-1) of de novo formed Ang I and 6.2+/-2.8 fmol x 100 mL(-1) x min(-1) of Ang II to antecubital venous blood. Fractional conversion of 125I-Ang I through forearm vascular tissue was about 12%. Low sodium diet increased (P<.01) plasma renin activity, whereas de novo Ang I and Ang II formation by forearm vascular tissue became undetectable. Angiotensin degradation (33+/-7% for Ang I and 30+/-7% for Ang II) was unchanged, and vascular fractional conversion of 125I-Ang I decreased from 12% to 6% (P<.01). In high sodium diet subjects, plasma renin activity decreased, and de novo Ang I and Ang II formation by forearm vascular tissue increased to 22 and 14 fmol x 100 mL(-1) x min(-1), respectively (P<.01). Angiotensin degradation did not significantly change, whereas fractional conversion of 125I-Ang I increased from 12% to 20% (P<.01). Leg vascular tissue functional activities of RAS paralleled those of forearm vascular tissue both at baseline and during different sodium intake. These results provide consistent evidence for the existence of a functional tissue-based RAS in vascular tissue of humans. The opposite changes of plasma renin activity and vascular angiotensin formation indicate that vascular RAS is independent from but related to circulating RAS. 相似文献
100.
Morimoto M. Orihara K. Mutoh N. Toyoda A. Ohbo M. Kawakami Y. Nakano T. Chiba K. Kawai S. Hatano K. Arai K. Nishimura M. Nakashiba Y. Kohno A. Akiyama I. Teranishi N. Hokari Y. 《Electron Devices, IEEE Transactions on》1995,42(1):50-57
A 1-inch 2-million pixel FIT-CCD image sensor for HDTV has been developed, which features a tungsten photo-shield and horizontal CCD (H-CCD) shunt wiring. Tungsten photo-shield, which has low reflectance and good step coverage characteristics, reduces smear level to -110 dB, combined with a frame-interline-transfer (FIT) scheme. The tungsten photo-shield also acts as a shunt busline, supplying transfer pulses to vertical CCD (V-CCD) electrodes, so that a 1.2×10ˆ5 electron charge handling capability is obtained at a frame transfer frequency of 1 MHz. Newly developed H-CCD shunt wiring suppresses vertical line pair FPN, even with smaller transfer pulse amplitudes. H-CCD shunt wiring also helps reduce power consumption in the H-CCD by 2/3 as compared to that achieved with conventional wiring 相似文献