首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   766篇
  免费   11篇
  国内免费   1篇
电工技术   21篇
综合类   2篇
化学工业   198篇
金属工艺   17篇
机械仪表   15篇
建筑科学   14篇
能源动力   32篇
轻工业   49篇
无线电   79篇
一般工业技术   147篇
冶金工业   130篇
原子能技术   11篇
自动化技术   63篇
  2024年   14篇
  2023年   14篇
  2022年   21篇
  2021年   28篇
  2020年   18篇
  2019年   15篇
  2018年   20篇
  2017年   24篇
  2016年   26篇
  2015年   10篇
  2014年   27篇
  2013年   38篇
  2012年   34篇
  2011年   45篇
  2010年   29篇
  2009年   30篇
  2008年   23篇
  2007年   25篇
  2006年   20篇
  2005年   17篇
  2004年   15篇
  2003年   12篇
  2002年   8篇
  2001年   8篇
  2000年   14篇
  1999年   15篇
  1998年   55篇
  1997年   40篇
  1996年   29篇
  1995年   13篇
  1994年   14篇
  1993年   16篇
  1992年   6篇
  1991年   4篇
  1990年   5篇
  1989年   3篇
  1988年   3篇
  1987年   7篇
  1986年   2篇
  1983年   2篇
  1982年   4篇
  1981年   3篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1976年   4篇
  1974年   2篇
  1973年   3篇
  1972年   2篇
  1968年   1篇
排序方式: 共有778条查询结果,搜索用时 0 毫秒
611.
Bloody urine was grossly observed and multinodular shadow confirmed in both lungs of an 81-year-old male, who had been referred to our department. The diagnosis was bladder cancer (TCC, G3, T4N3M1) from detailed examination. With his advanced age and lowered ADL, the family did not wish for aggressive treatment, so no combination multidrug chemotherapy was attempted. Instead he was given 300 mg/day UFT per os. After 4 weeks administration, the metastatic focus decreased and tended to contract; at the same time gross observation revealed no more bloody urine. Moreover, following 7 weeks of administration, the bladder tumor disappeared, the lung metastatic focus showed overall shrinkage of over 50%, the lymph node metastasis also was more than 50% less, and the case was considered to be PR. The literature reveals UFT was efficacious in only 2 other cases of progressive bladder carcinoma. Since UFT has fewer complications, such as myelosuppression, among antitumor agent, it is considered worth trying in cases where intensive treatment is not feasible.  相似文献   
612.
Electroluminescence (EL) properties of AlN:Tb thin film EL device (TFELD) prepared on a glass substrate by a rf-magnetron sputtering method have been studied. The AlN:Tb emission layer consists of hexagonal (110)-oriented poly-crystals of AlN with a high transparency in visible region. Four emission peaks originating from 5D→ 7F j (j = 6, 5, 4, 3) transitions of Tb3+ were found in both photoluminescence (PL) and EL spectra of the AlN:Tb thin film. The peak emission intensity of the 5D→ 7F6 transitions is almost the same magnitude with that of the 5D→ 7F5 transitions, being largely different from the intensity ratio of Tb3+in other host materials.  相似文献   
613.
We have fabricated a new layered structure, named "U-mag," for perpendicular magnetic recording media, in terms of stacked films including a very thin (2 nm) ferromagnetic (Co) intermediate layer and lattice spacing control layers. The formed medium having a 100-nm soft magnetic underlayer with high coercivity over 6 kOe and sufficient nucleation field (-1.5 kOe) shows higher signal-to-noise ratio (SNR) than a medium with a conventional Ru underlayer. The detailed microstructures of the U-mag medium were also revealed by a transmission electron microscope with an energy dispersive spectrometer. A double Co intermediate layer gave a significant improvement in the SNR compared to a single Co layer.  相似文献   
614.
Murata  Yuya  Cavallucci  Tommaso  Tozzini  Valentina  Pavliček  Niko  Gross  Leo  Meyer  Gerhard  Takamura  Makoto  Hibino  Hiroki  Beltram  Fabio  Heun  Stefan 《Nano Research》2018,11(2):864-873
Nano Research - Si dangling bonds at the interface of quasi-free-standing monolayer graphene (QFMLG) are known to act as scattering centers that can severely affect carrier mobility. Herein, we...  相似文献   
615.
We realize a uniform submicron-gap electrode by using an electrospun single fiber as a shadow-mask. By stretching an electrospun fiber, we can decrease the diameter of the fiber from 2 μm to 564 nm with its standard deviation of 57.7 nm. We place the fiber on the center of a Si/SiO2 substrate followed by the deposition of a molybdenum trioxide adhesion layer and Au electrode. After removing the fiber from the Si/SiO2 substrate, the submicron-gap gold electrode is formed. Characterization of the gap with scanning electron microscope revealed that the gap has a good uniformity; the average gap length is 865 nm throughout 2 mm gap width.  相似文献   
616.
The effect of solute ions on the thermal expansion of ZrP2O7 solid solutions was studied. The abrupt thermal expansion at the high-low inversion can be interpreted as due to the rotation of the polyhedra from the low-temperature form in the partially collapsed state to the high-temperature form in the fully expanded state. The replacement of zirconium ions by larger ions and/or the stuffing of cations into the cavities of the framework stabilized the expanded structure, and then depressed the abruptness of the expansion. Consequently the thermal expansion was reduced in Ce x Zr1-x P2O7 or (Li, Y) x Zr1-x P2O7 solid solutions.  相似文献   
617.
High-damping materials are widely used in engineering fields. In order to increase the precision of vibration control to different levels, high-damping materials with high-rigidity are required. This study attempts to develop a new high-damping high-rigidity material using ductile ceramics based on the Al2TiO5–MgTi2O5 system, which has many continuous microcracks along the grain boundaries. Ductile ceramics have high internal friction (Q −1 = 0.01–0.037), but very low rigidity (<10 GPa). The rigidity of Al2TiO5–MgTi2O5 ceramics was improved by combining them with a polymer such as acrylic resin. The Young’s modulus and internal friction of the composites of Al2TiO5–MgTi2O5 ceramics and acrylic resin are investigated. They show high-damping capacity (Q −1 = 0.03–0.04) with high rigidity (E = 50–60 GPa), and their properties depend on those of the polymer. Thus, the composites fabricated using the above method can serve as high-damping high-rigidity materials.  相似文献   
618.
Shoji Y  Mizumoto T 《Applied optics》2006,45(27):7144-7150
A wideband design is proposed for nonreciprocal phase shift magneto-optical isolators based on Mach-Zehnder interferometers. The wavelength dependence of nonreciprocal phase difference between the backward waves propagating in two interferometer arms is compensated for by that of reciprocal phase difference. This is realized by introducing an appropriate phase bias in one of interferometer arms. Two design examples are presented with a backward loss of >30 dB in the wavelength range of 1.40-1.63 microm for a magnetic garnet waveguide isolator and of 1.485-1.630 microm for a Si-wire waveguide isolator.  相似文献   
619.
为了去除与法兰装配面数据点混合在一起的噪声并更好地保留装配面的特征,将装配面点云数据中的噪声分为 2 类。利用空间栅格划分将点云数据栅格化,使用 K 领域搜索的方法筛选出第 1 类噪声点,运用采样点邻域点数统计法删除第 1 类噪声点;采用改进的双边滤波法对第 2 类噪声点进行去噪。通过与各类算法进行比较,实验结果表明,该去噪算法在达到预期去噪效果的同时还可以增加装配面特征的保持度,并且能够避免传统双边滤波在去噪后产生光顺过度的现象。  相似文献   
620.
Sn-filled carbon nanofibres (CNFs) are fabricated by microwave plasma chemical deposition. Scanning electron microscopy observations revealed the existence of a Sn island under the CNFs. The structure of the CNFs is investigated, and the behaviour of Sn in the internal space of CNFs is revealed by performing in situ heating observations by environmental transmission electron microscopy (ETEM). ETEM observations reveal that they have low-crystallized carbon wall and Sn occupies not only the CNF’s internal space but also its carbon wall. The Sn inside the CNF is completely covered by the carbon wall. Further, the in situ heating observations reveal that Sn within the internal space and the carbon wall of the CNFs diffused to the outside during heating. Moreover, it is found that higher membered carbon rings and defects in the graphite layer act as diffusion routes between disordered carbon layers.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号