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   8811篇
  免费   572篇
  国内免费   12篇
电工技术   119篇
综合类   5篇
化学工业   2283篇
金属工艺   133篇
机械仪表   299篇
建筑科学   326篇
矿业工程   17篇
能源动力   375篇
轻工业   1677篇
水利工程   118篇
石油天然气   52篇
武器工业   2篇
无线电   486篇
一般工业技术   1253篇
冶金工业   857篇
原子能技术   62篇
自动化技术   1331篇
  2024年   28篇
  2023年   82篇
  2022年   310篇
  2021年   396篇
  2020年   249篇
  2019年   279篇
  2018年   336篇
  2017年   358篇
  2016年   386篇
  2015年   264篇
  2014年   360篇
  2013年   688篇
  2012年   571篇
  2011年   700篇
  2010年   469篇
  2009年   499篇
  2008年   437篇
  2007年   375篇
  2006年   317篇
  2005年   216篇
  2004年   185篇
  2003年   176篇
  2002年   161篇
  2001年   113篇
  2000年   111篇
  1999年   113篇
  1998年   307篇
  1997年   220篇
  1996年   139篇
  1995年   98篇
  1994年   60篇
  1993年   58篇
  1992年   26篇
  1991年   20篇
  1990年   22篇
  1989年   24篇
  1988年   19篇
  1987年   12篇
  1986年   18篇
  1985年   21篇
  1984年   24篇
  1983年   22篇
  1982年   14篇
  1981年   15篇
  1980年   14篇
  1979年   9篇
  1978年   7篇
  1977年   15篇
  1976年   26篇
  1975年   6篇
排序方式: 共有9395条查询结果,搜索用时 15 毫秒
61.
Long-term effects after blood or bone marrow transplantation (BMT) are emerging as an important issue, as more patients are included in BMT programmes and as this procedure becomes more successful. Long-term liver dysfunction, mainly due to chronic graft-versus-host disease or hepatitis C virus infection, is a well-known complication. Nevertheless, the diagnosis of liver disease in this patient group is sometimes difficult and, despite adequate studies, it may remain undetected. A novel hepatitis-associated virus, hepatitis G virus (HGV), has recently been identified. The virus belongs to the Flaviviridae family and is known to be parenterally transmitted, although there is no clear evidence to implicate this agent in causing acute or chronic hepatitis. We report a patient who developed mild, but persistent, abnormalities in transaminases for 2 years after an autologous BMT. HGV RNA was detected in both serum and liver. HGV RNA persisted in serum for at least 8 months. No other known hepatitis virus was found. This report provides the first direct evidence of a patient with long-term liver abnormalities after a BMT in whom the only known hepatitis virus isolated was the HGV.  相似文献   
62.
The article presents a review of most important research results as well as opinions about the role and importance of body image disturbances in the development and the course of eating disorders. It also contains a review of definitions of body image, and techniques used in the evaluation of this type of disorders.  相似文献   
63.
64.
Total volatile basic nitrogen (TVB-N) as a measure of protein degradation and total microbial counts or stored raw mackerel (Trachurus murphy), which had been treated with chemical preservatives, were compared with the TVB-N and microbial counts of untreated fish. In unpreserved fish, decomposition of fish protein was rapid. Treatment of mackerel with acetic (1000-5000 μg kg?1), which was the most effective of the parameters studied, approximately halved the rate of increase in TVB-N compared with the untreated samples. Changes in the total microbial counts presented a similar trend.  相似文献   
65.
66.
The first part of this paper analyses the influence of the molecular weight and concentration of carboxymethyl cellulose (CMC) and of kaolin concentration on rheology of the coating colours and on paper properties coated with ultra lightweight coatings (ULWC). In the second part, relationships between the rheological characteristics of the coating colour formulations and coated paper surface quality was also studied.New indexes on paper roughness at micro-scale are presented (RZI and SRI). In general, they show good correlation with sheet gloss. A new gloss index (SGI) is presented, accounting for the contribution of gloss from machine direction (MD) and cross direction (CD). Porosimetry was used to access microstructural characteristics in order to correlate them with light scattering and gloss properties. The former property is closely related to Hg intrusion volume of the coated layer while gloss is related to surface porosity with pore diameters in the range of 7–15 μm as measured by Hg intrusion volume.  相似文献   
67.
A three-dimensional (3D) computational fluid dynamics (CFD) model of a contact tank is presented in this paper. The model results are compared against 3D velocities and flow through curve (FTC) data, representing a tracer concentration profile, from a 1:8 scale physical model. The objective is to demonstrate that CFD models can simulate both the FTC and the 3D velocity field quite well. Simultaneous validation of velocities and FTC is important in ascertaining the predictive capabilities of CFD models, as physical model studies indicate that different baffle arrangements can lead to similar FTCs. Therefore, a good prediction of only FTC, as presented in previous 3D CFD model studies, does not necessarily imply a correct simulation of the flow field.  相似文献   
68.
69.
70.
We compute the temperature dependent magnetic susceptibility of the single-impurity, two-channel Anderson model with an alternative multi-step numerical renormalization-group transformation, previously applied only to the two-impurity single-channel Kondo model. Compared with the traditional transformation, the new procedure requires substantially less memory and computational time, and opens therefore perspectives for the application of the numerical renormalization-group procedure to more complex Hamiltonians.  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