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   38740篇
  免费   3857篇
  国内免费   1927篇
电工技术   2218篇
技术理论   6篇
综合类   2693篇
化学工业   6559篇
金属工艺   2435篇
机械仪表   2570篇
建筑科学   2900篇
矿业工程   1393篇
能源动力   1117篇
轻工业   2630篇
水利工程   750篇
石油天然气   2308篇
武器工业   284篇
无线电   4363篇
一般工业技术   4733篇
冶金工业   1968篇
原子能技术   507篇
自动化技术   5090篇
  2024年   252篇
  2023年   863篇
  2022年   1567篇
  2021年   2170篇
  2020年   1628篇
  2019年   1284篇
  2018年   1352篇
  2017年   1491篇
  2016年   1363篇
  2015年   1682篇
  2014年   2133篇
  2013年   2401篇
  2012年   2507篇
  2011年   2725篇
  2010年   2340篇
  2009年   2166篇
  2008年   1973篇
  2007年   1716篇
  2006年   1626篇
  2005年   1419篇
  2004年   1045篇
  2003年   1039篇
  2002年   1082篇
  2001年   1049篇
  2000年   814篇
  1999年   887篇
  1998年   742篇
  1997年   595篇
  1996年   537篇
  1995年   443篇
  1994年   379篇
  1993年   267篇
  1992年   210篇
  1991年   156篇
  1990年   121篇
  1989年   106篇
  1988年   76篇
  1987年   51篇
  1986年   57篇
  1985年   24篇
  1984年   29篇
  1983年   27篇
  1982年   20篇
  1981年   19篇
  1980年   13篇
  1979年   15篇
  1978年   5篇
  1976年   13篇
  1970年   6篇
  1951年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
文章采用Logistic混沌序列对实时视频传输系统进行数据的分块加/解密,并从算法的安全性、效率等方面进行了性能分析,该算法具有良好的实时性、快速性和易实施性,可以有效地防止敏感信息被轻易的窃取、篡改和传播,有效保障网络视频传输的流畅性及安全性。  相似文献   
72.
不法分子为了逃避过滤,将不良信息中的敏感关键词进行变形。为了识别这些变形的关键词,提出了一种柔性过滤算法。在此基础上,利用浏览器帮助对象(BHO),构建了一个中文网页内容柔性过滤器,用于实时过滤由变形关键词生成的不良网页。该过滤器改善了传统过滤器不能过滤变形关键词的现状,是对传统的基于关键词过滤方法的补充。  相似文献   
73.
决策支持系统合理应用到跨部门电子政务工程中不但可以降低大量的人力和财力成本,还会为电子政务中半结构化或非结构化问题提供重要的决策支持。文章提供了一种跨部门电子政务工程中决策支持系统技术架构的设计,为决策支持系统在跨部门电子政务工程中的实现提供了一种方法。  相似文献   
74.
Although arthroscopic Bankart repair has become an accepted surgical stabilization technique for anterior shoulder instability, the failure rate remains unacceptably high. Little information is available concerning healing of the Bankart repair. The purpose of this article is to clarify this issue by analyzing a cohort of 15 patients who underwent a "second-look" arthroscopy to evaluate and treat pain or recurrent instability following arthroscopic Bankart repair with the Suretac device (Acufex Microsurgical, Mansfield, MA). "Second-look" arthroscopy was performed at an average of 9 months following the index surgical procedure. The reasons for this second surgery were recurrent instability in 7, pain in 6, and pain and stiffness in 2. In the 7 patients with recurrent instability, the Bankart repair was found to be completely healed in 3 (43%), partially healed in 1 (14%), and had recurred in 3 (43%); however, 6 of 7 were observed to have lax capsular tissue. In 4 of these cases, retrospective review of the index surgical procedure showed that a technical error had been made during the repair. Two cases had biopsy of the repair site on "second-look" at 6 to 8 months, and this showed residual polyglyconate polymer debris surrounded by a histiocytic infiltrate. In the remaining 8 cases with stable shoulders, the Bankart repair had completely healed in 5 cases (62.5%) and partially healed in 3 cases (37.5%). The higher failure rate with this approach compared with open approaches appears to result from improper patient selection and errors in surgical technique. There is some question concerning healing strength of the Bankart repair, although complete healing of the Bankart does not seem to be a prerequesite for shoulder stability. Success of the procedure might be expected to improve by selecting only patients with unidirectional, posttraumatic, anterior instability who are found to have a discrete Bankart lesion and well-developed ligamentous tissue.  相似文献   
75.
Radiotherapy is identified as a crucial treatment for patients with glioblastoma, but recurrence is inevitable. The efficacy of radiotherapy is severely hampered partially due to the tumor evolution. Growing evidence suggests that proneural glioma stem cells can acquire mesenchymal features coupled with increased radioresistance. Thus, a better understanding of mechanisms underlying tumor subclonal evolution may develop new strategies. Herein, data highlighting a positive correlation between the accumulation of macrophage in the glioblastoma microenvironment after irradiation and mesenchymal transdifferentiation in glioblastoma are presented. Mechanistically, elevated production of inflammatory cytokines released by macrophages promotes mesenchymal transition in an NF-κB-dependent manner. Hence, rationally designed macrophage membrane-coated porous mesoporous silica nanoparticles (MMNs) in which therapeutic anti-NF-κB peptides are loaded for enhancing radiotherapy of glioblastoma are constructed. The combination of MMNs and fractionated irradiation results in the blockage of tumor evolution and therapy resistance in glioblastoma-bearing mice. Intriguingly, the macrophage invasion across the blood-brain barrier is inhibited competitively by MMNs, suggesting that these nanoparticles can fundamentally halt the evolution of radioresistant clones. Taken together, the biomimetic MMNs represent a promising strategy that prevents mesenchymal transition and improves therapeutic response to irradiation as well as overall survival in patients with glioblastoma.  相似文献   
76.
Qian  Li Ping  Han  Shuai  Ji  Bo  Zhang  Yan 《Mobile Networks and Applications》2022,27(3):1081-1083
Mobile Networks and Applications -  相似文献   
77.
Wang  Bilin  Wang  Shengsheng  Zhang  Zhe  Zhao  Xin  Fu  Zihao 《Applied Intelligence》2022,52(12):14070-14084
Applied Intelligence - Unsupervised Domain Adaptation (UDA) aims to transfer knowledge from a label-rich source domain to an unlabeled target domain with a different but related distribution....  相似文献   
78.
Liu  Zixian  Du  Guansan  Zhou  Shuai  Lu  Haifeng  Ji  Han 《Computational Economics》2022,59(4):1481-1499
Computational Economics - The study aims to analyze and forecast Internet financial risks based on the model based on deep learning and the Back Propagation Neural Network (BPNN). First, the theory...  相似文献   
79.
80.
The capability to study the dynamic formation of plasmonic molecular junction is of fundamental importance, and it will provide new insights into molecular electronics/plasmonics, single‐entity electrochemistry, and nanooptoelectronics. Here, a facile method to form plasmonic molecular junctions is reported by utilizing single gold nanoparticle (NP) collision events at a highly curved gold nanoelectrode modified with a self‐assembled monolayer. By using time‐resolved electrochemical current measurement and surface‐enhanced Raman scattering spectroscopy, the current changes and the evolution of interfacial chemical bonding are successfully observed in the newly formed molecular tunnel junctions during and after the gold NP “hit‐n‐stay” and “hit‐n‐run” collision events. The results lead to an in‐depth understanding of the single NP motion and the associated molecular level changes during the formation of the plasmonic molecular junctions in a single NP collision event. This method also provides a new platform to study molecular changes at the single molecule level during electron transport in a dynamic molecular tunnel junction.  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