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   90570篇
  免费   7936篇
  国内免费   4081篇
电工技术   5708篇
技术理论   2篇
综合类   5777篇
化学工业   14160篇
金属工艺   4961篇
机械仪表   5217篇
建筑科学   6724篇
矿业工程   1853篇
能源动力   2654篇
轻工业   7093篇
水利工程   1812篇
石油天然气   3877篇
武器工业   675篇
无线电   12043篇
一般工业技术   11677篇
冶金工业   4622篇
原子能技术   1029篇
自动化技术   12703篇
  2024年   370篇
  2023年   1381篇
  2022年   2578篇
  2021年   3565篇
  2020年   2503篇
  2019年   2108篇
  2018年   2360篇
  2017年   2801篇
  2016年   2456篇
  2015年   3398篇
  2014年   4449篇
  2013年   5670篇
  2012年   6043篇
  2011年   6758篇
  2010年   5864篇
  2009年   5658篇
  2008年   5590篇
  2007年   5350篇
  2006年   5130篇
  2005年   4187篇
  2004年   2852篇
  2003年   2359篇
  2002年   2387篇
  2001年   2034篇
  2000年   1923篇
  1999年   1948篇
  1998年   1834篇
  1997年   1583篇
  1996年   1416篇
  1995年   1187篇
  1994年   934篇
  1993年   765篇
  1992年   615篇
  1991年   469篇
  1990年   388篇
  1989年   304篇
  1988年   255篇
  1987年   183篇
  1986年   152篇
  1985年   140篇
  1984年   100篇
  1983年   78篇
  1982年   71篇
  1981年   60篇
  1980年   54篇
  1979年   35篇
  1978年   34篇
  1977年   32篇
  1976年   56篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Neural Machine Translation (NMT) is an end-to-end learning approach for automated translation, overcoming the weaknesses of conventional phrase-based translation systems. Although NMT based systems have gained their popularity in commercial translation applications, there is still plenty of room for improvement. Being the most popular search algorithm in NMT, beam search is vital to the translation result. However, traditional beam search can produce duplicate or missing translation due to its target sequence selection strategy. Aiming to alleviate this problem, this paper proposed neural machine translation improvements based on a novel beam search evaluation function. And we use reinforcement learning to train a translation evaluation system to select better candidate words for generating translations. In the experiments, we conducted extensive experiments to evaluate our methods. CASIA corpus and the 1,000,000 pairs of bilingual corpora of NiuTrans are used in our experiments. The experiment results prove that the proposed methods can effectively improve the English to Chinese translation quality.  相似文献   
63.
64.
65.
66.
This paper presents a novel approach to the localization of moving targets in a complex environment based on the measurement of the perturbations induced by the target presence on an independently‐generated time‐varying electromagnetic field. Field perturbations are measured via a set of sensors deployed over the domain of interest and used to detect and track a possible target by resorting to a particle Bernoulli filter (PBF). To comply with real‐time operation, the PBF works along with an artificial neural network (ANN) model of the environment trained offline via finite elements (FEs). The performance of the proposed algorithm is assessed via simulation experiments.  相似文献   
67.
Perovskite ferroelectrics possess the fascinating piezoelectric properties near a morphotropic phase boundary, attributing to a low energy barrier that the results in structural instability and easy polarization rotation. In this work, a new lead-free system of (1-x)BaTiO3-xCaHfO3 was designed, and characterized by a coexistence of ferroelectric rhombohedral-orthorhombic-tetragonal (R-O-T) phases. With the increase amount of CaHfO3 (x), a stable coexistence region of three ferroelectric phases (R-O-T) exists at 0.06  x  0.08. Both large piezoelectric coefficient (d33~400 pC/N), inverse piezoelectric coefficient (d33*~547 pm/V) and planar electromechanical coupling factor (kp~58.2%) can be achieved for the composition with x = 0.08 near the coexistence of three ferroelectric phases. Our results show that the materials with the composition located at a region where the three ferroelectric R-O-T phases coexist would have the lowest energy barrier and thus greatly promote the polarization rotation, resulting in a strong piezoelectric response.  相似文献   
68.
Kong  Hao  Lu  Canyi  Lin  Zhouchen 《Machine Learning》2021,110(7):1867-1900
Machine Learning - Recently, the $${ Tensor}~{ Nuclear}~{ Norm}~{ (TNN)}$$ regularization based on t-SVD has been widely used in various low tubal-rank tensor recovery tasks. However, these models...  相似文献   
69.
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA.  相似文献   
70.
垦71井区三维VSP资料波场分离方法应用研究   总被引:8,自引:5,他引:3  
张卫红  陈林  高志凌 《石油物探》2006,45(5):532-536
三维VSP资料是多偏移距VSP资料,资料中多种类型的波叠合在一起形成复杂波场。从复杂波场中分离出单一的保幅反射波波场是三维VSP波场分离的重要工作。常规二维VSP波场处理方法单一,难以适用于复杂的三维波场处理。针对三维VSP资料的波场特点,以分离上行反射P波为例,将单一波场分离方法加以适当组合,对垦71井区三维VSP实际资料进行了应用研究。结果表明,波场分离处理中叠加消去法和中值滤波相结合以及F—K滤波和中值滤波相结合的方法克服了单一方法的缺陷,波场处理后获得了波组特征明显、波场清晰单一的上行反射P波保幅波场,取得了较好的波场分离效果。  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