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   1985篇
  免费   70篇
  国内免费   9篇
电工技术   107篇
综合类   3篇
化学工业   559篇
金属工艺   53篇
机械仪表   34篇
建筑科学   42篇
矿业工程   4篇
能源动力   114篇
轻工业   221篇
水利工程   2篇
石油天然气   3篇
武器工业   1篇
无线电   118篇
一般工业技术   411篇
冶金工业   181篇
原子能技术   55篇
自动化技术   156篇
  2023年   6篇
  2022年   7篇
  2021年   45篇
  2020年   17篇
  2019年   30篇
  2018年   39篇
  2017年   31篇
  2016年   45篇
  2015年   31篇
  2014年   50篇
  2013年   104篇
  2012年   83篇
  2011年   115篇
  2010年   87篇
  2009年   104篇
  2008年   119篇
  2007年   98篇
  2006年   90篇
  2005年   97篇
  2004年   80篇
  2003年   79篇
  2002年   68篇
  2001年   45篇
  2000年   45篇
  1999年   44篇
  1998年   78篇
  1997年   63篇
  1996年   37篇
  1995年   43篇
  1994年   46篇
  1993年   42篇
  1992年   28篇
  1991年   23篇
  1990年   11篇
  1989年   20篇
  1988年   16篇
  1987年   11篇
  1986年   11篇
  1985年   9篇
  1984年   10篇
  1983年   13篇
  1982年   9篇
  1981年   5篇
  1979年   5篇
  1978年   3篇
  1977年   4篇
  1976年   5篇
  1973年   3篇
  1972年   2篇
  1968年   2篇
排序方式: 共有2064条查询结果,搜索用时 15 毫秒
1.
Background: Within the claudin (CLDN) family, CLDN12 mRNA expression is altered in various types of cancer, but its clinicopathological relevance has yet to be established due to the absence of specific antibodies (Abs) with broad applications. Methods: We generated a monoclonal Ab (mAb) against human/mouse CLDN12 and verified its specificity. By performing immunohistochemical staining and semiquantification, we evaluated the relationship between CLDN12 expression and clinicopathological parameters in tissues from 138 cases of cervical cancer. Results: Western blot and immunohistochemical analyses revealed that the established mAb selectively recognized the CLDN12 protein. Twenty six of the 138 cases (18.8%) showed low CLDN12 expression, and the disease-specific survival (DSS) and recurrence-free survival rates were significantly decreased compared with those in the high CLDN12 expression group. We also demonstrated, via univariable and multivariable analyses, that the low CLDN12 expression represents a significant prognostic factor for the DSS of cervical cancer patients (HR 3.412, p = 0.002 and HR 2.615, p = 0.029, respectively). Conclusions: It can be concluded that a reduced CLDN12 expression predicts a poor outcome for cervical cancer. The novel anti-CLDN12 mAb could be a valuable tool to evaluate the biological relevance of the CLDN12 expression in diverse cancer types and other diseases.  相似文献   
2.
3.
We have investigated the characteristics of radiated electromagnetic (EM) waves from positive and negative partial discharges (PD) in epoxy resin and cross‐linked polyethylene. We found that there is a correlation among the EM level from PD, the positive PD current, and electrical trees. Therefore, the growth of an electrical tree produces a lot of positive PD. We have also investigated the characteristics of the frequency region of EM waves from PD in air, insulating oil, and liquid epoxy in addition to the above insulators. EM waves were detected in the frequency region of 40 MHz to 300 MHz from positive and negative PD in epoxy resin and cross‐linked polyethylene. EM waves were also detected in the frequency region of 40 MHz to 150 MHz from positive and negative PD in air. In the case of insulating oil and liquid epoxy, EM waves were detected in the frequency regions of 40 MHz to 150 MHz from positive PD, and 40 MHz to 250 MHz from negative PD. The frequency region differed depending on the material and the discharge polarity. Our investigation indicates that the cause is differences in electric field strength at the time of PD occurrence.  相似文献   
4.
The microbial transformation of l‐menthol ( 1 ) was investigated by using 12 isolates of soil‐borne plant pathogenic fungi, Rhizoctonia solani (AG‐1‐IA Rs24, Joichi‐2, RRG97‐1; AG‐1‐IB TR22, R147, 110.4; AG‐1‐IC F‐1, F‐4, P‐1; AG‐1‐ID RCP‐1, RCP‐3, and RCP‐7) as a biocatalyst. Rhizoctonia solani F‐1, F‐4 and P‐1 showed 89.7–99.9% yields of converted product from 1 , RCP‐1, RCP‐3, and RCP‐7 26.0–26.9% and the other isolates 0.1–12.0%. In the cases of F‐1, F‐4 and P‐1, substrate 1 was converted to (?)‐(1S,3R,4S,6S)‐6‐hydroxymenthol ( 2 ), (?)‐(1S,3R,4S)‐1‐hydroxymenthol ( 3 ) and (+)‐(1S,3R,4R,6S)‐6,8‐dihydroxymenthol ( 4 ), which was a new compound. Substrate 1 was converted to 2 and/or 3 by RRG97‐1, 110.4, RCP‐1, RCP‐3 and RCP‐7. The structures of the metabolic products were elucidated on the basis of their spectral data. In addition, metabolic pathways of the biotransformation of 1 by Rhizoctonia solani are discussed. Finally, from the main component analysis and the differences in the yields of converted product from 1 , the 12 isolates of Rhizoctonia solani were divided into three groups based on an analysis of the metabolites. Copyright © 2003 Society of Chemical Industry  相似文献   
5.
6.
Specimens of partially stabilized zirconia were slip cast from aqueous suspensions and sintered at 1500°C for 3 h. The relative density of the cast specimens and the firing shrinkage of the sintered specimens depend on the milling time for the suspension. Vickers hardness and KIC values of 11.46±s0.07 GN/m2 and 6.10 ±0.04 MN.m3/2, respectively, were obtained for all sintered specimens. The dispersion of the suspension is important in increasing the relative density of the cast specimens.  相似文献   
7.
A 16 Mb embedded DRAM macro in a fully CMOS logic compatible 90 nm process with a low noise core architecture and a high-accuracy post-fabrication tuning scheme has been developed. Based on the proposed techniques, 61% improvement of the sensing accuracy is realized. Even with the smallest 5 fF/cell capacitance, a 322 MHz random-cycle access while 32 ms data retention time which contributes to save the data retention power down to 60 /spl mu/W are achieved.  相似文献   
8.
The deuterium (hydrogen) passivation effect on acceptors in boron-doped CVD homoepitaxial diamond was studied by electrical (Hall-effect) and secondary ion mass spectroscopy (SIMS) measurements. Deuterium was incorporated into the samples using microwave (MW) deuterium plasma at 673 K for 2–24 h. We observed the progress of acceptor passivation with p-type conduction, which finally resulted in a highly resistive state.  相似文献   
9.
10.
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