全文获取类型
收费全文 | 1177篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 49篇 |
化学工业 | 174篇 |
金属工艺 | 40篇 |
机械仪表 | 51篇 |
建筑科学 | 19篇 |
能源动力 | 38篇 |
轻工业 | 90篇 |
水利工程 | 6篇 |
无线电 | 137篇 |
一般工业技术 | 190篇 |
冶金工业 | 284篇 |
原子能技术 | 22篇 |
自动化技术 | 114篇 |
出版年
2023年 | 4篇 |
2022年 | 16篇 |
2021年 | 18篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 27篇 |
2013年 | 54篇 |
2012年 | 33篇 |
2011年 | 44篇 |
2010年 | 43篇 |
2009年 | 33篇 |
2008年 | 49篇 |
2007年 | 37篇 |
2006年 | 41篇 |
2005年 | 43篇 |
2004年 | 29篇 |
2003年 | 16篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 33篇 |
1998年 | 115篇 |
1997年 | 58篇 |
1996年 | 65篇 |
1995年 | 42篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 27篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1214条查询结果,搜索用时 0 毫秒
31.
Xi Zhang Author Vitae Wai-Ming Tsang Author Vitae Author Vitae Kazuo Yamazaki Author Vitae 《Computers in Industry》2010,61(7):711-726
Collision detection by machining simulation requires the 3D models of rotating cutters. However, the 3D models of a cutter and holder are not always available. In this paper, a new method is proposed to design an automatic vision-based 3D modeling system, which is able to quickly reconstruct the 3D model of a cutter and holder when they are installed onto the spindle. Only a single camera is mounted on the machine tool to capture the image of the rotating cutter and holder. By viewing the rotating cutter and holder as an object of surface of revolution, the contour of the imaged cutter and holder can be used to reconstruct the 3D model as a stack of circular cross-sections. Then the complete generating function of the cutter and holder can be recovered from the cross-sections. Finally, the 3D model of the cutter is built by rotating the generating function around the spindle axis. The effectiveness and accuracy of the proposed method are verified by experiments on-machine using 12 kinds of cutters and holders, which can satisfy the requirement of collision detection. 相似文献
32.
Parametric interpolation has been widely used in CNC machining because of its advantages over the traditional linear or circular interpolation. Many researchers focused on this field and have made great progress in the specific one, NURBS curve interpolation. These works greatly improved the CNC machining with constant feedrate, confined chord error and limited acceleration/deceleration. However, during CNC machining process, mechanical shocks to machine tool caused by the undesired acceleration/deceleration profile will dramatically deteriorate the surface accuracy and quality of the machined parts. This is, in most occasions, very harmful to machine tools. In this paper, an accurate adaptive NURBS curve interpolator is proposed with consideration of acceleration–deceleration control. The proposed design effectively reduces the machining shocks by constraining the machine tool jerk dynamically. Meanwhile, the constant feedrate is maintained during most time of machining process, and thus high accuracy is achieved while the feedrate profile is greatly smoothed. In order to deal with the sudden change of the acceleration/deceleration around the corner with large curvature, a real-time flexible acceleration/deceleration control scheme is introduced to adjust the feedrate correspondingly. Case study has been taken to verify the feasibility and advantages of the proposed design. 相似文献
33.
34.
Characterization of terrestrial water dynamics in the Congo Basin using GRACE and satellite radar altimetry 总被引:1,自引:0,他引:1
Hyongki Lee R. Edward Beighley Hahn Chul Jung Jianbin Duan Dai Yamazaki 《Remote sensing of environment》2011,115(12):3530-3538
The Congo Basin is the world's third largest in size (~ 3.7 million km2), and second only to the Amazon River in discharge (~ 40,200 m3 s− 1 annual average). However, the hydrological dynamics of seasonally flooded wetlands and floodplains remains poorly quantified. Here, we separate the Congo wetland into four 3° × 3° regions, and use remote sensing measurements (i.e., GRACE, satellite radar altimeter, GPCP, JERS-1, SRTM, and MODIS) to estimate the amounts of water filling and draining from the Congo wetland, and to determine the source of the water. We find that the amount of water annually filling and draining the Congo wetlands is 111 km3, which is about one-third the size of the water volumes found on the mainstem Amazon floodplain. Based on amplitude comparisons among the water volume changes and timing comparisons among their fluxes, we conclude that the local upland runoff is the main source of the Congo wetland water, not the fluvial process of river-floodplain water exchange as in the Amazon. Our hydraulic analysis using altimeter measurements also supports our conclusion by demonstrating that water surface elevations in the wetlands are consistently higher than the adjacent river water levels. Our research highlights differences in the hydrology and hydrodynamics between the Congo wetland and the mainstem Amazon floodplain. 相似文献
35.
A new approach for the solution of singular optima in truss topology optimization with stress and local buckling constraints 总被引:3,自引:1,他引:2
The present paper investigates problems of truss topology optimization under local buckling constraints. A new approach for
the solution of singular problems caused by stress and local buckling constraints is proposed. At first, a second order smooth-extended
technique is used to make the disjoint feasible domains connect, then the so-called ε-relaxed method is applied to eliminate
the singular optima from problem formulation. By means of this approach, the singular optimum of the original problem caused
by stress and local buckling constraints can be searched approximately by employing the algorithms developed for sizing optimization
problems with high accuracy. Therefore, the numerical problem resulting from stress and local buckling constraints can be
solved in an elegant way. The applications of the proposed approach and its effectiveness are illustrated with several numerical
examples.
Received May 2, 2000 相似文献
36.
37.
Koichiro Hirano Masafumi Fukuda Mikio Takano Yoshio Yamazaki Toshiya Muto Sakae Araki Nobuhiro Terunuma Masao Kuriki Mitsuo Akemoto Hitoshi Hayano Junji Urakawa 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2006,560(2):233-239
A multi-bunch photo-cathode RF gun system has been developed as an electron source for the production of intense quasi-monochromatic X-rays based on inverse Compton scattering. The desired multi-bunch beam is 100 bunches/pulse with a total charge of 500 nC and a bunch spacing of 2.8 ns. We modified the gun cavity of a ‘BNL-type IV’ RF gun to allow a CsTe cathode plug in the end plate. The system uses a four-dipole chicane beam line to allow the injection of laser light normal to the cathode surface. We compensate the gun cavity beam loading caused by the high-intensity multi-bunch electron beam by injecting the laser pulse before RF power has filled the cavity. We have achieved a total intensity of 220 nC in 100 bunches with a bunch-to-bunch energy spread under 1.3% (peak-to-peak). This paper concentrates on experiments to generate the high-intensity multi-bunch beam with compensation of the bunch-to-bunch energy spread due to heavy beam loading. 相似文献
38.
M. Ishimoto Y. Yamazaki K. Shinohe A. Tokai H. Hirakawa H. Yamada K. Awamoto T. Shinoda 《Journal of the Society for Information Display》2004,12(3):263-268
Abstract— The plasma‐tube array is expected to realize a wall‐sized display. This method will realize an emissive‐type display with a flexible screen shape and an expandable screen size. The shape of the plasma tube was investigated to realize high luminance, high luminance efficacy, and high flexural strength. As the result, a cylindroid tube is proposed to satisfy these demands. An experimental display of 1 m × 128 mm has been developed with these cylindroid tubes and it demonstrated a high luminous efficacy of 3.1 lm/W. 相似文献
39.
Masanori Ono Natsumi Toyoda Kyosuke Kagami Takashi Hosono Takeo Matsumoto Shin-ichi Horike Rena Yamazaki Mitsuhiro Nakamura Yasunari Mizumoto Tomoko Fujiwara Hitoshi Ando Hiroshi Fujiwara Takiko Daikoku 《International journal of molecular sciences》2022,23(14)
Recently, it was demonstrated that the expression of BMAL1 was decreased in the endometrium of women suffering from recurrent spontaneous abortion. To investigate the pathological roles of uterine clock genes during pregnancy, we produced conditional deletion of uterine Bmal1 (cKO) mice and found that cKO mice could receive embryo implantation but not sustain pregnancy. Gene ontology analysis of microarray suggested that uterine NK (uNK) cell function was suppressed in cKO mice. Histological examination revealed the poor formation of maternal vascular spaces in the placenta. In contrast to WT mice, uNK cells in the spongiotrophoblast layer, where maternal uNK cells are directly in contact with fetal trophoblast, hardly expressed an immunosuppressive NK marker, CD161, in cKO mice. By progesterone supplementation, pregnancy could be sustained until the end of pregnancy in some cKO mice. Although this treatment did not improve the structural abnormalities of the placenta, it recruited CD161-positive NK cells into the spongiotrophoblast layer in cKO mice. These findings indicate that the uterine clock system may be critical for pregnancy maintenance after embryo implantation. 相似文献
40.
Shunpei Yamazaki Takuya Hirohashi Masahiro Takahashi Shunsuke Adachi Masashi Tsubuku Junichi Koezuka Kenichi Okazaki Yohsuke Kanzaki Hiroshi Matsukizono Seiji Kaneko Shigeyasu Mori Takuya Matsuo 《Journal of the Society for Information Display》2014,22(1):55-67
Our crystalline In–Ga–Zn oxide (IGZO) thin film has a c‐axis‐aligned crystal (CAAC) structure and maintains crystallinity even on an amorphous base layer. Although the crystal has c‐axis alignment, its a‐axis and b‐axis have random arrangement; moreover, a clear grain boundary is not observed. We fabricated a back‐channel‐etched thin‐film transistor (TFT) using the CAAC‐IGZO film. Using the CAAC‐IGZO film, more stable TFT characteristics, even with a short channel length, can be obtained, and the instability of the back channel, which is one of the biggest problems of IGZO TFTs, is solved. As a result, we improved the process of manufacturing back‐channel‐etched TFTs. 相似文献