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   3678篇
  免费   238篇
  国内免费   3篇
电工技术   28篇
化学工业   757篇
金属工艺   86篇
机械仪表   115篇
建筑科学   129篇
矿业工程   11篇
能源动力   192篇
轻工业   813篇
水利工程   13篇
石油天然气   19篇
无线电   441篇
一般工业技术   587篇
冶金工业   168篇
原子能技术   35篇
自动化技术   525篇
  2024年   16篇
  2023年   51篇
  2022年   55篇
  2021年   139篇
  2020年   104篇
  2019年   105篇
  2018年   163篇
  2017年   122篇
  2016年   159篇
  2015年   132篇
  2014年   150篇
  2013年   517篇
  2012年   142篇
  2011年   160篇
  2010年   168篇
  2009年   170篇
  2008年   98篇
  2007年   77篇
  2006年   67篇
  2005年   46篇
  2004年   36篇
  2003年   36篇
  2002年   38篇
  2001年   84篇
  2000年   87篇
  1999年   86篇
  1998年   127篇
  1997年   111篇
  1996年   46篇
  1995年   26篇
  1994年   21篇
  1993年   24篇
  1990年   13篇
  1985年   15篇
  1984年   13篇
  1976年   20篇
  1973年   11篇
  1924年   17篇
  1917年   14篇
  1916年   27篇
  1912年   12篇
  1909年   15篇
  1908年   12篇
  1907年   17篇
  1906年   14篇
  1905年   18篇
  1901年   13篇
  1900年   12篇
  1899年   13篇
  1898年   27篇
排序方式: 共有3919条查询结果,搜索用时 15 毫秒
11.
The Journal of Supercomputing - Deep learning algorithms have yielded remarkable results in medical diagnosis and image analysis, besides their contribution to improvements in a number of fields...  相似文献   
12.
The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies.  相似文献   
13.
Herein, we report the use of tungsten(VI) oxide (WO3) as support for Rh0 nanoparticles. The resulting Rh0/WO3 nanoparticles are highly active and stable catalysts in H2 generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh0/WO3 catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh0/WO3 (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min?1 in releasing 3.0 equivalent H2 per mole of AB from the hydrolysis at 25.0 °C. The high catalytic activity of Rh0/WO3 catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh0/WO3 (0.5 % wt. Rh) catalyst in the hydrolysis reaction.  相似文献   
14.
Phospholamban (PLN) was expressed in Escherichia coli as a protein fusion with glutathione S-transferase (GST). GST-PLN was mostly present in the insoluble protein fraction and accounted for approximately 50% of total insoluble protein. Attempts to suppress inclusion body formation or to use GST as an affinity-purification tag failed. A successful purification method is based on preparative SDS/PAGE and electrodialysis. From 1 g cells we typically purified 13.5 mg fusion protein with a PLN content of 2.8 mg. We genetically inserted an enterokinase (EK) protease site just in front of the PLN sequence and demonstrated the proteolytical liberation of PLN from the carrier protein. The approach described represents a substantial advancement in PLN expression and purification.  相似文献   
15.
16.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time.  相似文献   
17.
The past decade may be regarded as the phase of the fundamental developments in fieldbus systems that were based on the OSI model. Today we are entering a second stage. It is the objective of this issue to present the current state and where the further developments will lead to. This introductory article is intended to give an overview on the subject.  相似文献   
18.
Recently appeared defects on high voltage cables have required an urgent evaluation of the impact of lightning strikes necessary. In some cases overvoltages between the copper wire screen of the cable and earth may appear which cause damages of the cablesheath. Field measurements with a classification of the voltage impulses at the copper wire screen have been made to evaluate the number of events. Additionally a numerical model was developed to study the effects of atmospheric discharges on underground cables with emphasis to the influence on the cablesheath. This numeric method was also applied to estimate the effectiveness of different protection arrangements. This contribution presents evaluation methods for overvoltages of cables and a model used firstly for calculating the stress caused by differential voltages and secondly to determinate the influence of protection measures.  相似文献   
19.
Hemiballism is a rare hyperkinetic disorder which is characterized by irregular vigorous rotatory movements of the limbs of one side of the body. The disabling and exhausting movements with their high risk of severe injuries require an acute drug treatment. However, there are no common guidelines for the treatment of this disorder. Therefore we reviewed the available literature to establish a concept for a rational symptomatic drug treatment. Furthermore, own observations in 6 patients with hemiballism of different origins are reported.  相似文献   
20.
The aim of this study was to determine the tocopherol contents of wine by-products including grape seed, pomace (seed, skin and stem) and bagasse (skin and stem) by using two different extraction methods in order to evaluate the possibilities of them as natural non-polar antioxidants. Cold extraction appeared to give more tocopherol contents in seeds than hot extraction. But hot extraction was found more suitable for pomace and bagasse. α-Tocopherol was the most abundant tocopherol in the grape seed, pomace and bagasse. Although γ- and δ-tocopherols were found in the samples with low concentrations, β-tocopherol was not detected in the samples. Kalecik karası had the highest α and total tocopherol compared to the other cultivars. On the other hand, hot extracted bagasse in all cultivars gave the highest tocopherol contents. As a conclusion, wine by-products, a large scale wastes, can be evaluated both to get natural tocopherol source and to obtain economical gain.  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