首页 | 官方网站   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   191篇
  免费   2篇
  国内免费   1篇
工业技术   194篇
  2024年   1篇
  2023年   1篇
  2021年   1篇
  2020年   1篇
  2018年   1篇
  2017年   2篇
  2016年   1篇
  2014年   1篇
  2013年   5篇
  2011年   10篇
  2010年   4篇
  2009年   8篇
  2008年   4篇
  2007年   9篇
  2006年   4篇
  2005年   10篇
  2004年   5篇
  2003年   4篇
  2002年   5篇
  2001年   3篇
  2000年   5篇
  1999年   9篇
  1998年   24篇
  1997年   17篇
  1996年   11篇
  1995年   6篇
  1994年   7篇
  1993年   5篇
  1992年   2篇
  1991年   7篇
  1990年   3篇
  1989年   4篇
  1988年   3篇
  1986年   1篇
  1985年   4篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1976年   1篇
  1972年   1篇
排序方式: 共有194条查询结果,搜索用时 15 毫秒
41.
42.
The zone-annealing method was attempted to prepare high-modulus and high-strength poly(ethylene terephthalate) (PET) film. The film having Young′s modulus of 14.5 × 1010 dyn/cm2 and a tensile strength of 86.9 kg/mm2 in the drawing direction was obtained. These values correspond to four times those of a biaxial-stretched PET film available commercially. The dyanmic viscoelastic properties also were measured. The dynamic storage modulus was 15.4 × 1010 dyn/cm2 at room temperature, and a high value of 3.6 × 1010 dyn/cm2 even at 200°C. The latter value is slightly higher than the room temperature modulus of the commercially available film. From the intensity and temperature position of α-dispersion E″ peak, it was suggested that the amorphous chains in the zone-annealed film was densely packed in a highly oriented state. Furthermore, the crystallinity, orientation, especially double orientation, and molecular chain conformation of the films in the zone-annealing process are discussed in the present paper.  相似文献   
43.
A 32-year-old female, who was admitted with complaints of cough and an abnormal shadow in the left lower lobe, was diagnosed as adenocarcinoma of the lung by TBLB. She underwent left lower lobectomy and lymph node dissection. Histopathological findings showed well differentiated fetal adenocarcinoma (WDFA). Well differentiated fetal adenocarcinomas are considered to have a histogenesis similar to that of pulmonary blastoma and may be a tumor with one-sided development of pulmonary blastoma showing only an epithelial component.  相似文献   
44.
A growth-inhibiting activity was identified in supernatants of the neoplastic V79 Chinese hamster cell line based on its ability to inhibit the proliferation of the same cell line. The partially purified activity, provisionally termed "growth inhibiting factor" (GIF) activity, inhibited the growth of a wide variety of human tumor cells, but not various normal human fibroblasts. This species-nonspecific activity was reversible, saturable, and highly potent in tumorigenic cell lines, and was noted in both monolayer culture and in soft agar. The inhibitory activity of GIF was also exhibited in a chemically defined serum-free medium supplemented with insulin and transferrin. GIF activity was stable to acid, heat, trypsin, and dithiothreitol but sensitive to alpha-chymotrypsin. The pattern of growth modulation by GIF on V79 cells was apparently different from those exhibited by bifunctional peptides such as transforming growth factor-beta, tumor necrosis factor-alpha, and interleukin-1-alpha. In addition, GIF activity cannot be ascribed to these cytokines based on the physicochemical and immunologic properties. Although GIF has yet to be purified to homogeneity, these data suggest that GIF might be a novel growth regulator which has a critical role in regulating growth of V79 cells. The growth modulation of tumor cells by this tumor-derived growth inhibiting activity suggested the presence of an autocrine growth regulatory mechanism even in tumor cells.  相似文献   
45.
纳米金属微粒催化制备的洋葱状富勒烯的结构表征   总被引:9,自引:5,他引:9  
采用金属Cu,Al做粒/石墨混合材料.用直流电弧放电方法制备了洋葱状富勒烯。对两种产物进行了XRD、SEM、HRTEM和Raman结构表征。结果表明:两种纳米金属微粒均可催化得到洋葱状富勒烯;所得产物中有单纯洋葱状富勒烯和内包纳米金属微粒洋葱状富勒烯,且石墨化程度都很高;纳米金属微粒尺寸大小不同决定洋葱状富勒烯的直径分布不均匀,从而造成其拉曼谱峰相对于石墨特征峰1582cm^-1发生了频移;用汽-液-固(VLS)生长模型描述了洋葱状富勒烯生长机理,解释了汽态碳原子通过在液态催化剂中扩散和析出,逐渐长大成形的现象。  相似文献   
46.
In this paper, the long-term trends in surface temperature in several large Asian cities (Seoul, Tokyo, Osaka, Taipei, Manila, Bangkok, and Jakarta) have been analyzed for estimating the effects of urban warming. A new index, E-HII, is proposed: it is the value obtained by subtracting the temperature data of the four grids around the city from the observational temperature data in the city. Osaka shows the largest E-HII, increasing from approximately 2.4 °C in 1901 to almost 3 °C after 1981. The E-HIIs of Seoul, Tokyo, and Taipei, have increased by 1 °C to 2 °C. Jakarta and Bangkok exhibited a lower E-HII. E-HIIs of Manila and Bangkok have been increasing rapidly after 1961.  相似文献   
47.
This paper focuses on selection of wind turbine generation systems that include generators, converters, and gears. We study three systems: a permanent magnet generator (PMG) system, a doubly‐fed generator (DFG) system, and a synchronous generator (SYG) system in terms of the system efficiencies and running costs. The system efficiencies and running costs are calculated by considering the relationship between wind power and wind conditions. According to these results, the one‐step gear PMG system is the best choice for a large wind turbine system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 51–57, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20506  相似文献   
48.
To analyze the effects of stress-shielding on graft maturation after the anterior cruciate ligament (ACL) reconstruction, autogenous ACL reconstruction using Achilles tendon was performed in rabbits. Two-end fixation with a ligament augmentation device (LAD), as a stress-shielding model (SS group), and pull-out fixation with Leeds-Keio artificial ligaments (L-K ligament), as a non-stress-shielding model (non-SS group), were investigated. Intact ACL was used as the control. Specimens were harvested 6 mon postoperatively, and the analysis was focused on collagen fibril maturation in the mid-substance and bone-anchoring pattern in the bone tunnel, under light and transmission electron microscopy. The density of collagen fibrils in the control was lower than that in both experimental groups (p<0.01). The per cent collagen area in the control was higher than that in the SS (p<0.01) and the non-SS group (p<0.01). The per cent collagen area in the non-SS group was higher than that in the SS group (p<0.05). At the ligament-bone interface, intracellular calcification of the degenerated chondrocytes occurred in the non-SS group, while in the SS group hydroxyapatite deposits were observed only in the extracellular matrix. These results show unfavorable influence of stress-shielding on graft maturation not only in the mid-substance but also at the ligament-bone junction. © 1999 Kluwer Academic Publishers  相似文献   
49.
50.
Atomic-resolution high-resolution high-voltage transmission electron microscopy was applied to the chemical structure analysis of silicon carbide. Each atomic column was imaged in dark contrast. Silicon and carbon were distinguished from each other in image contrast, i.e. silicon appeared in darker contrast and carbon appeared in lighter contrast. For the projected potential image to provide chemical structure information, it was estimated that the specimen thickness needs to be less than 5 nm. The precise atomic columnar site was determined by using the maximum entropy method.  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-23

京公网安备 11010802026262号