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   454460篇
  免费   12067篇
  国内免费   5500篇
电工技术   12129篇
技术理论   11篇
综合类   7161篇
化学工业   67432篇
金属工艺   22893篇
机械仪表   20078篇
建筑科学   16262篇
矿业工程   5304篇
能源动力   10643篇
轻工业   30062篇
水利工程   5685篇
石油天然气   13217篇
武器工业   734篇
无线电   53268篇
一般工业技术   87445篇
冶金工业   61765篇
原子能技术   9636篇
自动化技术   48302篇
  2022年   4213篇
  2021年   6085篇
  2020年   4653篇
  2019年   4618篇
  2018年   14258篇
  2017年   15205篇
  2016年   11067篇
  2015年   6784篇
  2014年   9277篇
  2013年   18176篇
  2012年   15933篇
  2011年   24457篇
  2010年   21092篇
  2009年   20986篇
  2008年   21171篇
  2007年   22581篇
  2006年   13820篇
  2005年   15894篇
  2004年   12600篇
  2003年   11599篇
  2002年   10108篇
  2001年   9613篇
  2000年   9420篇
  1999年   10097篇
  1998年   19132篇
  1997年   14056篇
  1996年   11158篇
  1995年   8731篇
  1994年   7554篇
  1993年   7268篇
  1992年   5350篇
  1991年   4925篇
  1990年   4662篇
  1989年   4542篇
  1988年   4131篇
  1987年   3671篇
  1986年   3584篇
  1985年   3908篇
  1984年   3564篇
  1983年   3294篇
  1982年   3107篇
  1981年   3091篇
  1980年   3071篇
  1979年   2858篇
  1978年   2893篇
  1977年   3164篇
  1976年   4131篇
  1975年   2425篇
  1974年   2384篇
  1973年   2405篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration.  相似文献   
55.
Traditionally, in supervised machine learning, (a significant) part of the available data (usually 50%-80%) is used for training and the rest—for validation. In many problems, however, the data are highly imbalanced in regard to different classes or does not have good coverage of the feasible data space which, in turn, creates problems in validation and usage phase. In this paper, we propose a technique for synthesizing feasible and likely data to help balance the classes as well as to boost the performance in terms of confusion matrix as well as overall. The idea, in a nutshell, is to synthesize data samples in close vicinity to the actual data samples specifically for the less represented (minority) classes. This has also implications to the so-called fairness of machine learning. In this paper, we propose a specific method for synthesizing data in a way to balance the classes and boost the performance, especially of the minority classes. It is generic and can be applied to different base algorithms, for example, support vector machines, k-nearest neighbour classifiers deep neural, rule-based classifiers, decision trees, and so forth. The results demonstrated that (a) a significantly more balanced (and fair) classification results can be achieved and (b) that the overall performance as well as the performance per class measured by confusion matrix can be boosted. In addition, this approach can be very valuable for the cases when the number of actual available labelled data is small which itself is one of the problems of the contemporary machine learning.  相似文献   
56.
Journal of Communications Technology and Electronics - Abstract—The two-dimensional diffraction problem of a plane polarized TM-wave on two identical solid silver nanocylinders is considered....  相似文献   
57.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
58.
徐浩  吴炜  陈浩  王子康 《电子测试》2020,(10):117-118,27
无人机技术目前的快速发展使得我们国家输电线路自身的巡检能力得到了持续的提升,基于此本文在对无人机技术给予认识的情况下,在了解了输电线路巡检过程中的使用优势之后,还总结了无人机技术在当前我国线路巡检过程中的应用路径以及应用方法;之后使用案例分析的方式分析了无人机技术在当前输电线路巡检过程中的应用方法。  相似文献   
59.
Yan  Jing  Zhu  Rongying  Wu  Fan  Zhao  Ziyin  Ye  Huan  Hou  Mengying  Liu  Yong  Yin  Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally...  相似文献   
60.
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition.  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