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981.
Soh Maruyama Kazuyuki Takase Ryutaroh Hino Naoki Izawa Hiroshi Kawamura Hiroaki Shimomura 《Nuclear Engineering and Design》1987,102(1)
Tests on heat transfer and fluid-dynamics of the mock-up fuel stack of the Very High Temperature Gas Cooled Reactor (VHTR) were performed by the multi-channel test rig (T1 - M) of the Helium Engineering Demonstration Loop (HENDEL). The T1 - M simulated one column of the fuel stack in the VHTR core and contained twelve simulated fuel rods. The heat generation rate of each fuel rod was varied to simulate the power distribution of the VHTR core in the horizontal plane. In parallel with this experiment, a three-dimensional thermal analysis code was developed in order to check the experimental temperature distribution of the fuel stack.Experimental results showed that the distribution of the helium gas flow rate was influenced by the temperature distortion in the mock-up fuel stack. The maximum deviation of the helium gas flow rate from the mean value was 10% in the case of an asymmetric power distribution test at a low Reynolds number. The variation of the calculated temperature distribution in the fuel stack was about 17-35°C in each case, indicating that the temperature distortion in the fuel stack was flattened by thermal conduction in the graphite block. 相似文献
982.
Indium phosphide dry etching is carried out using a reactive beam extracted from a Br2-N2 gas discharge plasma. Keeping the N2 gas pressure constant at 0.23 mTorr, the Br2 gas pressure was varied from 0 to 0.1 mTorr and the sample temperature was varied from 40 to 200°C. The etched shapes and
etching rates are investigated in terms of the etching beam composition. Two distinct types of etching mechanisms come into
play depending on the Br2 gas pressure. Smooth vertical side walls and a temperature independent etching rate can be obtained at a Br2 gas pressure of 0.04 mTorr or less and a temperature above 100°C, where the etching is induced by the ambient Br2 gas species and N2 beam. Undercut etching with a temperature dependent etching rate is seen at a Br2 gas pressure of 0.07 mTorr or higher, where the etching beam contains both N2 and Br2 gas species. Neutralized Br species generated by the discharge of the Br2 gas are shown to form the undercut. A waveguide corner mirror with a loss of less than 1 dB is made by using an etching beam
with no neutralized Br species. 相似文献
983.
To write a reliable program in an assembly language for microprocessor-based controller, we introduce data abstraction facility into an assembly language. For this purpose, we has designed and implemented ADT-RASM86 and its symbolic debugger. This paper presents the figure of the system and describes how the system is effective for writing a reliable program for microprocessors. 相似文献
984.
N Hirono E Mori M Yasuda Y Ikejiri T Imamura T Shimomura M Ikeda M Hashimoto H Yamashita 《Canadian Metallurgical Quarterly》1998,64(5):648-652
BACKGROUND: The incidence of abdominal aortic aneurysm (AAA) has increased steadily during the past 30 years. METHODS: Trends in the incidence and surgical intervention for AAA in Western Australia were reviewed for the interval 1985-1994. A population-based health database was used to link morbidity and mortality records of all patients aged 55 years or more who died from rupture or were admitted and treated surgically for AAA. Three groups were separated for analysis: patients with a ruptured AAA, those admitted for elective repair and those admitted as an emergency with an acute (non-ruptured) aneurysm. RESULTS: There was a decline in the incidence of both emergency and elective procedures for AAA after 1992. While the mortality rate from ruptured AAA has also fallen since 1991, the overall case fatality rate for ruptured AAA has fallen by only 1.3 per cent (from 80.7 to 79.3 per cent). CONCLUSION: The decline in mortality rate and emergency procedures may result from a fall in the incidence of ruptured AAA, due to an increasing rate of elective surgery before 1992. The decline in elective procedures from 1992 may be due to a fall in the prevalence of AAA owing to high rates of elective surgery, or to a fall in the incidence of the disease itself. 相似文献
985.
Hoonjoo Na Hyeongjoon Kim Kazuhiro Adachi Norihiko Kiritani Satoshi Tanimoto Hideyo Okushi Kazuo Arai 《Journal of Electronic Materials》2004,33(2):89-93
We have fabricated planar 4H-SiC, metal-semiconductor field-effect transistors (MESFETs) with high-quality metal/SiC contacts.
To eliminate potential damage to the gate region caused by etching and simplify the device fabrication process, gate Schottky
contacts were formed without any recess gate etching, and an ideality factor of 1.03 was obtained for these gate contacts.
The interface state density between the contact metal and SiC was 5.7×1012 cm−2eV−1, which was found from the relationship between the barrier height and the metal work function. These results indicate that
the interface was well controlled. Thus, a transconductance of 30 mS/mm was achieved with a 3-μm gate length as the performance
figure of these MESFETs with high-quality metal/SiC contacts. Also, a low ohmic contact resistance of 1.2×10−6 Θcm2 was obtained for the source and drain ohmic contacts by using ion implantation. 相似文献
986.
Satoshi Iwakata Yoshiaki Ajioka Masafumi Hagiwara 《Electrical Engineering in Japan》2006,157(2):50-56
In this paper, we propose a thresholding algorithm. This algorithm works under a severe constraint: each pixel in a processed image must be derived from only information of its neighboring pixels. This constraint is very important for a low‐cost device such as a mobile camera, because it makes it possible to process each pixel in parallel. The proposed algorithm deals with gray‐scale images, and determines the threshold based on edge information. The proposed algorithm is represented by local and parallel image processing and has been tested using 104 scenery images. The result shows that the proposed algorithm can binarize images. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 50–56, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20267 相似文献
987.
Satoshi Tanaka Chiu Chia Pin Keizo Uematsu 《Journal of the American Ceramic Society》2006,89(6):1903-1907
The influence of binder systems on the structure and properties of alumina ceramics was examined. Two types of binders were used to prepare alumina granules by spray drying: poly-acrylic acid (PAA) and poly-vinyl alcohol (PVA). PVA segregated to the surface and subsurface of the granules, whereas PAA was homogeneously distributed. Compaction tests on a single granule showed that the PAA binder provides lower yield stress of granules than PVA. In the die compaction process, the relative density of the compact body started to increase at a lower pressure, and a more homogeneous internal structure was observed in the green compact prepared with the PAA binder than PVA. The homogeneous structure resulted in a sintered body with a strength of 580 vs 485 MPa when PVA was used. 相似文献
988.
Pichai Jintakosonwit Hirofumi Akagi Hideaki Fujita Satoshi Ogasawara 《Electrical Engineering in Japan》2003,142(4):56-65
This paper discusses automatic gain adjustment in a fully‐digital‐controlled shunt active filter intended for installation on power distribution systems. This is the first step in cooperative control of multiple shunt active filters based on voltage detection for harmonic damping throughout power distribution systems. In general, an optimal control gain is equal to the characteristic impedance of a distribution line. However, it is difficult to know the circuit parameters of a real distribution line, which depend strongly on feeder connections, shunt capacitors, and loads. Therefore, the main purpose of the gain adjustment is to help the active filter to damp out harmonic propagation without considering the circuit parameters. Moreover, the gain adjustment can reduce the compensating current and losses in the active filter. The active filter having the function of automatic gain adjustment is experimentally compared to that with a constant gain. Experiment results verify the effectiveness of the active filter having the function of automatic gain adjustment. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 142(4): 56–65, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10094 相似文献
989.
Takahiro Takada Keisuke Kageyama Mitsuharu Yonemura Naoki Hara Satoshi Takao 《Journal of Materials Science: Materials in Electronics》2003,14(4):205-214
The effect of different chemical compositions on the microwave dielectric properties of Ba(Zn1/3Ta2/3)O3–xCaTiO3 and xMgTiO3–yCaTiO3–z(Nd2O3,wTiO2) was studied. High fQ dielectrics were designed by optimizing composition and firing conditions. Adding up to 1 mol % CaTiO3 to Ba(Zn1/3Ta2/3)O3 increased εr from 25 to 30 at a firing temperature of 1450 °C, and produced very high fQ values of more than 100 000 GHz at a firing temperature of 1550 °C. EPMA and XRD suggested that ceramics based on Ba(Zn1/3Ta2/3)O3 with CaTiO3 had mixed phases of Ba(Zn1/3Ta2/3)O3 and Ca–Ti–Zn–O. Addition of CaTiO3 increased the Ba(Zn1/3Ta2/3)O3 peak observed in XRD and decreased the Ba3Ta2O8 peak. Prolonged sintering of Ba(Zn1/3Ta2/3)O3 with CaTiO3 increased the fQ value but kept εr constant. 0.5MgTiO3–0.5CaTiO3–z(Nd2O3,wTiO2) showed a high dielectric constant εr>40 and fQ>20 000 GHz. When w=1, τf decreased linearly with z around 0 ppm/ °C in 0.5MgTiO3–0.5CaTiO3–z(Nd2O3,TiO2) (0.25≤z≤0.5). X-ray and EDX analysis revealed a mixed phase matrix of MgTiO3 and (Ca1?αNd2α/3)TiβO3. It was concluded that εr of the high fQ materials Ba(Zn1/3Ta2/3)O3–xCaTiO3 and xMgTiO3–yCaTiO3–z(Nd2O3,wTiO2) would be increased by varying their chemical compositions, x, y, z, and w, and that their fQ value would be improved by appropriate choices of heating temperature and time. 相似文献
990.
This paper proposes a new selection method of a gene from a population for reducing the number of fitness value calculations in genetic algorithms. The proposed method effectively reduces the computation time required to search for a solution to the optimization of a process involving a large number of such calculations as in robot behavior decisions and neural network learnings. In the proposed method, the use of a special buffer for storing a gene and its associated fitness value is introduced. The gene in the buffer is used as a candidate for the solution to the optimization problem. This gene is compared with a gene selected from the population, and one of the values is used in the next generation depending on the results of the comparison. The proportion of suitable genes in the population is increased in the possible shortest time. The convergence speed of our buffer depends on the population topology, which is introduced for choosing a gene from the population to compare with the buffer gene. Three kinds of topology are applied to our algorithm and they are compared and evaluated. The proposed method is applied to a robot control problem to demonstrate the validity of the technique. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 42–49, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10148 相似文献