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   30163篇
  免费   3503篇
  国内免费   1398篇
电工技术   1827篇
技术理论   3篇
综合类   2013篇
化学工业   5188篇
金属工艺   1731篇
机械仪表   1918篇
建筑科学   2020篇
矿业工程   704篇
能源动力   1084篇
轻工业   2565篇
水利工程   616篇
石油天然气   1437篇
武器工业   195篇
无线电   3838篇
一般工业技术   4096篇
冶金工业   1203篇
原子能技术   373篇
自动化技术   4253篇
  2024年   474篇
  2023年   690篇
  2022年   1015篇
  2021年   1350篇
  2020年   1029篇
  2019年   936篇
  2018年   1045篇
  2017年   1036篇
  2016年   1128篇
  2015年   1241篇
  2014年   1512篇
  2013年   1792篇
  2012年   1908篇
  2011年   2141篇
  2010年   1777篇
  2009年   1697篇
  2008年   1634篇
  2007年   1551篇
  2006年   1483篇
  2005年   1290篇
  2004年   989篇
  2003年   1048篇
  2002年   1214篇
  2001年   1082篇
  2000年   746篇
  1999年   666篇
  1998年   449篇
  1997年   408篇
  1996年   387篇
  1995年   322篇
  1994年   207篇
  1993年   171篇
  1992年   156篇
  1991年   102篇
  1990年   77篇
  1989年   65篇
  1988年   53篇
  1987年   45篇
  1986年   35篇
  1985年   19篇
  1984年   13篇
  1983年   9篇
  1982年   13篇
  1981年   8篇
  1980年   11篇
  1979年   10篇
  1976年   3篇
  1975年   3篇
  1974年   6篇
  1973年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
本文对用户初始服务密码管理困难的原因进行了深入的分析,提出了将初始服务密码印制在SIM卡涂层下的新型管理方式。  相似文献   
72.
随着大量的各种类型的体育场馆的兴建,体育场馆的照明工程成为建筑电气行业的一个重要分支.在场馆建设时应根据实际需要进行照明设计和施工,做到场馆的照明满足体育赛事在安全、可靠、达标方面的要求,并且兼顾赛时与赛后照明设施的充分利用,达到既经济又实用的目的.体育场馆照明工程设计和施工中存在一些常见的缺陷,在设计和施工中应认真加以研究,以保证工程的质量.  相似文献   
73.
HDAC6 is overexpressed in ovarian cancer and is known to be correlated with tumorigenesis. Accordingly, ACY-241, a selective HDAC6 inhibitor, is currently under clinical trial and has been tested in combination with various drugs. HDAC8, another member of the HDAC family, has recently gained attention as a novel target for cancer therapy. Here, we evaluated the synergistic anticancer effects of PCI-34051 and ACY-241 in ovarian cancer. Among various ovarian cancer cells, PCI-34051 effectively suppresses cell proliferation in wild-type p53 ovarian cancer cells compared with mutant p53 ovarian cancer cells. In ovarian cancer cells harboring wild-type p53, PCI-34051 in combination with ACY-241 synergistically represses cell proliferation, enhances apoptosis, and suppresses cell migration. The expression of pro-apoptotic proteins is synergistically upregulated, whereas the expressions of anti-apoptotic proteins and metastasis-associated proteins are significantly downregulated in combination treatment. Furthermore, the level of acetyl-p53 at K381 is synergistically upregulated upon combination treatment. Overall, co-inhibition of HDAC6 and HDAC8 through selective inhibitors synergistically suppresses cancer cell proliferation and metastasis in p53 wild-type ovarian cancer cells. These results suggest a novel approach to treating ovarian cancer patients and the therapeutic potential in developing HDAC6/8 dual inhibitors.  相似文献   
74.
As the most recent melanocortin receptor (MCR) identified, melanocortin-5 receptor (MC5R) has unique tissue expression patterns, pharmacological properties, and physiological functions. Different from the other four MCR subtypes, MC5R is widely distributed in both the central nervous system and peripheral tissues and is associated with multiple functions. MC5R in sebaceous and preputial glands regulates lipid production and sexual behavior, respectively. MC5R expressed in immune cells is involved in immunomodulation. Among the five MCRs, MC5R is the predominant subtype expressed in skeletal muscle and white adipose tissue, tissues critical for energy metabolism. Activated MC5R triggers lipid mobilization in adipocytes and glucose uptake in skeletal muscle. Therefore, MC5R is a potential target for treating patients with obesity and diabetes mellitus. Melanocortin-2 receptor accessory proteins can modulate the cell surface expression, dimerization, and pharmacology of MC5R. This minireview summarizes the molecular and pharmacological properties of MC5R and highlights the progress made on MC5R in energy metabolism. We poInt. out knowledge gaps that need to be explored in the future.  相似文献   
75.
Neural Computing and Applications - To realize real-time fault detection in power devices and enhance reliability of inverter circuits, this paper proposes a detection method based on Park’s...  相似文献   
76.
需求管理、配置管理和项目范围管理在软件项目管理中具有重要的地位和作用。透彻分析了需求管理、配置管理和项目范围管理知识理论中的基本概念,有助于形成对需求管理、配置管理和项目范围管理的深刻理解,有利于规范和促进日常项目管理工作。  相似文献   
77.
通过介绍贵州电网输电线路在线监测系统的应用和运行情况,对系统在运行过程中发生的缺陷和故障进行了统计和梳理,通过对故障原因的分析,提出了相应的改进对策。  相似文献   
78.
Journal of Mechanical Science and Technology - Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage...  相似文献   
79.
With the introduction of low‐powered pico/femto‐base stations and relay nodes into the macro‐cell, recent heterogeneous networks provide an attractive approach for future wireless communication. Although it may achieve better coverage and higher capacity, several problems remain unsolved before practical deployment. For example, how to select the proper cell from neighbor low‐powered cells and then occupy the radio resource without interference on macro‐users is both important and challenging, especially for rigorous multimedia applications. The traditional cell access algorithms and quality‐control parameters such as delay or throughput no longer suit well in this complex environment. An effective approach should be pursued. In this paper, we investigate this interesting cell association problem and propose a complete green resolution on the basis of thorough discussions about the multimedia transmission under these concerns. Cognitive radio is introduced to share spectrum between macro‐cell and low‐powered cells while securing the transmission of authorized macro‐users. We also bring forth the concept of ‘interference balance’ to better manage the overall interference and energy consumption in the network. Restless bandit model is formulated on the basis of channel state, data rate, interference control, and the carefully chosen intra‐refreshing rate for multimedia traffic. Then the cell association scheme is designed to be efficient and practical because of the simple index property of our model output. Simulation results have proven the performance of our proposed resolution compared with existing algorithms on interference constraint, multimedia distortion, and overall network energy consumption balance. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
80.
Dual-wavelength lasing at 1480 and 1500 nm has been demonstrated from a cascaded Raman fibre laser with a WDM coupler and two pairs of Bragg gratings. Intensity-adjustable, wavelength-tunable laser operation was achieved by tensile stress wavelength tuning of the gratings  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