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   86469篇
  免费   7778篇
  国内免费   3994篇
电工技术   5427篇
技术理论   7篇
综合类   5539篇
化学工业   14601篇
金属工艺   4757篇
机械仪表   5002篇
建筑科学   6796篇
矿业工程   2774篇
能源动力   2531篇
轻工业   7244篇
水利工程   1556篇
石油天然气   5315篇
武器工业   729篇
无线电   9650篇
一般工业技术   10055篇
冶金工业   4273篇
原子能技术   1086篇
自动化技术   10899篇
  2024年   465篇
  2023年   1603篇
  2022年   2966篇
  2021年   4005篇
  2020年   3040篇
  2019年   2487篇
  2018年   2821篇
  2017年   3036篇
  2016年   2719篇
  2015年   3613篇
  2014年   4598篇
  2013年   5319篇
  2012年   5820篇
  2011年   6212篇
  2010年   5329篇
  2009年   4808篇
  2008年   4710篇
  2007年   4475篇
  2006年   4533篇
  2005年   3796篇
  2004年   2424篇
  2003年   2095篇
  2002年   1947篇
  2001年   1622篇
  2000年   1862篇
  1999年   2080篇
  1998年   1671篇
  1997年   1417篇
  1996年   1401篇
  1995年   1188篇
  1994年   989篇
  1993年   660篇
  1992年   543篇
  1991年   429篇
  1990年   341篇
  1989年   294篇
  1988年   230篇
  1987年   151篇
  1986年   132篇
  1985年   88篇
  1984年   73篇
  1983年   52篇
  1982年   51篇
  1981年   39篇
  1980年   32篇
  1979年   10篇
  1977年   10篇
  1976年   14篇
  1959年   9篇
  1951年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Yang  Xi  Gao  Ling  Guo  Qing  Li  Yongjiang  Ma  Yue  Yang  Ju  Gong  Changyang  Yi  Cheng 《Nano Research》2020,13(10):2579-2594

Over the past decade, numerous studies have attempted to enhance the effectiveness of radiotherapy (external beam radiotherapy and internal radioisotope therapy) for cancer treatment. However, the low radiation absorption coefficient and radiation resistance of tumors remain major critical challenges for radiotherapy in the clinic. With the development of nanomedicine, nanomaterials in combination with radiotherapy offer the possibility to improve the efficiency of radiotherapy in tumors. Nanomaterials act not only as radiosensitizers to enhance radiation energy, but also as nanocarriers to deliver therapeutic units in combating radiation resistance. In this review, we discuss opportunities for a synergistic cancer therapy by combining radiotherapy based on nanomaterials designed for chemotherapy, photodynamic therapy, photothermal therapy, gas therapy, genetic therapy, and immunotherapy. We highlight how nanomaterials can be utilized to amplify antitumor radiation responses and describe cooperative enhancement interactions among these synergistic therapies. Moreover, the potential challenges and future prospects of radio-based nanomedicine to maximize their synergistic efficiency for cancer treatment are identified.

  相似文献   
5.
6.
基于MSTP以太网专线进行远程视音频传输,是一种结构简单、线路便宜、容易搭建的传输系统.由于MSTP以太网专线的独特设计,点到点的透传方式,容易实现对用户MAC帧点到点的透传,在线路上能独享带宽,业务延迟小,且和其它业务完全隔离,安全性高,这种业务适合广播级视音频信号远程传输的应用.  相似文献   
7.
8.
In this study, in vitro digestion and fermentation of Flammulina velutipes -derived polysaccharides (FVP) were investigated. It was found that FVP mainly consisted of 48.45% glucose, 15.40% mannose, 14.60% xylose, 11.80% fucose and 9.90% galactose. The -human saliva, simulated gastric and small intestinal juices conditions did not break down the FVP. Based on in vitro fermentation tests, FVP modulated the composition of gut microbiota by elevating the amounts of Bifidobacteriaceae and Bacteroidaceae and reducing the numbers of genera Lachnospiraceae and Enterococcaceae. Meanwhile, FVP affected the synthesis of short-chain fatty acids derived from gut microbiota.  相似文献   
9.
Process object is the instance of process. Vertexes and edges are in the graph of process object. There are different types of the object itself and the associations between object. For the large-scale data, there are many changes reflected. Recently, how to find appropriate real-time data for process object becomes a hot research topic. Data sampling is a kind of finding c hanges o f p rocess o bjects. There i s r equirements f or s ampling to be adaptive to underlying distribution of data stream. In this paper, we have proposed a adaptive data sampling mechanism to find a ppropriate d ata t o m odeling. F irst o f all, we use concept drift to make the partition of the life cycle of process object. Then, entity community detection is proposed to find changes. Finally, we propose stream-based real-time optimization of data sampling. Contributions of this paper are concept drift, community detection, and stream-based real-time computing. Experiments show the effectiveness and feasibility of our proposed adaptive data sampling mechanism for process object.  相似文献   
10.
Electromagnetic signal emitted by satellite communication (satcom) transmitters are used to identify specific individual uplink satcom terminals sharing the common transponder in real environment, which is known as specific emitter identification (SEI) that allows for early indications and warning (I&W) of the targets carrying satcom furnishment and furthermore the real time electromagnetic situation awareness in military operations. In this paper, the authors are the first to propose the identification of specific transmitters of satcom by using probabilistic neural networks (PNN) to reach the goal of target recognition. We have been devoted to the examination by exploring the feasibility of utilizing the Hilbert transform to signal preprocessing, applying the discrete wavelet transform to feature extraction, and employing the PNN to perform the classification of stationary signals. There are a total of 1000 sampling time series with binary phase shift keying (BPSK) modulation originated by five types of satcom transmitters in the test. The established PNNs classifier implements the data testing and finally yields satisfactory accuracy at 8 dB(±1 dB) carrier to noise ratio, which indicates the feasibility of our method, and even the keen insight of its application in military.  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