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   472146篇
  免费   5791篇
  国内免费   1839篇
电工技术   9326篇
综合类   583篇
化学工业   68580篇
金属工艺   19658篇
机械仪表   14414篇
建筑科学   11621篇
矿业工程   1513篇
能源动力   11928篇
轻工业   43192篇
水利工程   4114篇
石油天然气   5135篇
武器工业   71篇
无线电   60688篇
一般工业技术   88045篇
冶金工业   92267篇
原子能技术   8578篇
自动化技术   40063篇
  2021年   3429篇
  2019年   3286篇
  2018年   5484篇
  2017年   5471篇
  2016年   5844篇
  2015年   4012篇
  2014年   6815篇
  2013年   20824篇
  2012年   11288篇
  2011年   15580篇
  2010年   12484篇
  2009年   13897篇
  2008年   15057篇
  2007年   15114篇
  2006年   13777篇
  2005年   12613篇
  2004年   12096篇
  2003年   12056篇
  2002年   11757篇
  2001年   11868篇
  2000年   11035篇
  1999年   11786篇
  1998年   29067篇
  1997年   20650篇
  1996年   16056篇
  1995年   12230篇
  1994年   10875篇
  1993年   10647篇
  1992年   7995篇
  1991年   7618篇
  1990年   7127篇
  1989年   6793篇
  1988年   6637篇
  1987年   5680篇
  1986年   5555篇
  1985年   6574篇
  1984年   6045篇
  1983年   5436篇
  1982年   5100篇
  1981年   5179篇
  1980年   4922篇
  1979年   4600篇
  1978年   4479篇
  1977年   5447篇
  1976年   7343篇
  1975年   3948篇
  1974年   3848篇
  1973年   3838篇
  1972年   3124篇
  1971年   2917篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Home parenteral nutrition (HPN) is used to treat intestinal failure. A minority of HPN patients are dependent on opiates and benzodiazepines to control pain and anxiety. The aim of this study was to determine what effects such drug dependence had on patient outcomes. METHODS: Ten dependent patients were prospectively compared with 10 well-matched, nondependent HPN patients for the same 12-month period. Episodes of line sepsis and other complications were documented and the cost of treatment estimated. Health status was measured using the SF36 and EuroQol instruments. RESULTS: The dependent group had significantly more episodes of central line sepsis (p = .0007) as well as other complications (p = .0002). This led to significantly longer periods of inpatient care (p = .0004) and therefore higher costs of treatment. Health status was lower in the dependent group; they reported more pain (p = .04) and less energy (p = .04). CONCLUSIONS: The complication rate and increased cost of treatment for opiate- and sedative-dependent patients receiving HPN significantly detract from the overall outcome of this therapy.  相似文献   
62.
63.
64.
A new commercially available diode model is described. This unified model is capable of simulating the widest range of diode technologies of any presently available. The emphasis of this paper is on describing the model's extensive features and flexibility in the different domains of operation and is of particular interest in power applications  相似文献   
65.
66.
67.
We present the design of E-kernel, an embedding kernel on the Victor V256 message-passing partitionable multiprocessor, developed for the support of program mapping and network reconfiguration. E-kernel supports the embedding of a new network topology onto Victor's 2D mesh and also the embedding of a task graph onto the 2D mesh network or the reconfigured network. In the current implementation, the reconfigured network can be a line or an even-size ring, and the task graphs meshes or tori of a variety of dimensions and shapes or graphs with similar topologies. For application programs having these task graph topologies and that are designed according to the communication model of E-kernel, they can be run without any change on partitions connected by the 2D mesh, line, or ring. Further, E-kernel attempts the communication optimization of these programs on the different networks automatically, thus making both the network topology and the communication optimization attempt completely transparent to the application programs. Many of the embeddings used in E-kernel are optimal or asymptotically optimal (with respect to minimum dilation cost). The implementation of E-kernel translated some of the many theoretical results in graph embeddings into practical tools for program mapping and network reconfiguration in a parallel system. E-kernel is functional on Victor V256. Measurements of E-kernel's performance on V256 are also included  相似文献   
68.
69.
70.
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