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101.
Kubuki M. Yoshimoto R. Tanoue K. Hara M. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1995,2(1):155-166
The DC breakdown characteristics of a sphere-to-sphere gap with conducting objects supported by an insulator rod in atmospheric air are investigated experimentally to provide fundamental parameters determining the breakdown voltage in the presence of floating objects around DC power apparatus by an air insulation. The shape of tested floating objects made of metal is plate, needle or sphere. Experimental results show that the main factors affecting the breakdown voltage are the shape and size of floating objects, the object location and the gap length. If the object is placed at the location giving the lowest breakdown voltage, any object lowers the breakdown voltage below that without the relevant objects 相似文献
102.
Kei?IwasakiEmail author Yoshinori?Dobashi Fujiichi?Yoshimoto Tomoyuki?Nishita 《The Visual computer》2008,24(2):77-84
Particle-based simulations are widely used to simulate fluids. We present a real-time rendering method for the results of
particle-based simulations of water. Traditional approaches to visualize the results of particle-based simulations construct
water surfaces that are usually represented by polygons. To construct water surfaces from the results of particle-based simulations,
a density function is assigned to each particle and a density field is computed by accumulating the values of the density
functions of all particles. However, the computation of the density field is time consuming. To address this problem, we propose
an efficient calculation of density field using a graphics processing unit (GPU). We present a rendering method for water
surfaces sampled by points. The use of the GPU permits efficient simulation of optical effects, such as refraction, reflection,
and caustics. 相似文献
103.
104.
Takashi Iizuka Kazuo Yoshimoto Hiroshi Takai Kaori Fukunaga Takashi Maeno 《Electrical Engineering in Japan》1999,129(3):9-16
Internal space charge behavior of insulating materials has recently attracted attention of many researchers, and a large number of experimental studies were carried out by using the materials for dc cables, such as XLPE, LDPE, and HDPE. Epoxy resins are used for insulation under strong electric fields in power apparatus and in electronic devices, and we investigated the behavior of internal space charge using the pulsed electroacoustic method. Two types of epoxy resins were studied: insulation-grade and craft-grade. When dc electric fields were applied to the craft resins treated by immersing them into room-temperature water for 8 and 24 h, positive and negative charges accumulated near the anode and the cathode, respectively, and the charge distribution changed with the immersion time. On the other hand, no charge was observed in the insulation-grade epoxy resin. Next, we treated the samples by immersing them into 100 °C water for 8 h. When the sample was treated for 8 h, hetero charge distribution, which means positive charges near the cathode and negative charges near the anode, was observed. This result is consistent with a previous paper reporting that by chemical analysis, secondary decomposition had occurred. These results show that water and temperature influence the internal space charge behavior of epoxy resins. © 1999 Scripta Technica, Electr Eng Jpn, 129(3): 9–16, 1999 相似文献
105.
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107.
Shaoqing Wang Kenichi Koumatsu Makoto Yoshimoto Katsumi Nakao 《Chemical engineering science》2003,58(15):3353-3360
The external loop airlift bubble column has been regarded as a promising type of gas-liquid or gas-liquid-solid biooreactor because of the liquid circulating flow between the riser and downcomer. A mini-scale column is useful and efficient in the process research and development for highly specialized materials such as fine chemicals, advanced bioproducts and biocatalysts utilized in two or three phase system. In this work, a mini-scale glass column of in volume was designed and characterized. The gas holdup εG in the riser was obtained by measuring the volume expansion through photographs taken with a digital camera. The liquid circulating velocity UL was measured by observing the time required for a tracer particle to travel a fixed distance in the downcomer through analysis of the images taken by a video camera. The gas-liquid volumetric oxygen transfer coefficient kLa and liquid-solid oxygen transfer coefficient kS were determined by our previous method in which the air oxidation of glucose was catalysed by the immobilized glucose oxidase gel beads suspended in the column to obtain a pseudo steady state concentration of the dissolved oxygen and the corresponding constant rate of glucose consumption. It was shown that even such a mini-scale external loop bubble column could be characterized in terms of gas holdup, liquid circulating velocity and mass transfer properties according to our previous correlations proposed for the bench to pilot scale column. 相似文献
108.
It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications. 相似文献
109.
110.
Yoshimoto M. Takine T. Takahashi Y. Hasegawa T. 《Communications, IEEE Transactions on》1993,41(11):1687-1693
The paper provides a performance analysis of automatic-repeat-request (ARQ) protocols in connection-oriented transmission. Each message arriving at a transmitter is divided into several packets, which are continuously transmitted to a receiver according to go-back-N ARQ or selective-repeat ARQ protocols. Because of connection-oriented transmission, messages are served on a first come first served basis, i.e., transmission of a message is commenced after all packets in the previous message are successfully transmitted. For the two ARQ protocols, the authors derive the probability generating functions of message waiting time and queue length at an arbitrary instant, from which the average performance measures are explicitly obtained 相似文献