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   2838篇
  免费   96篇
  国内免费   61篇
电工技术   69篇
综合类   138篇
化学工业   205篇
金属工艺   75篇
机械仪表   62篇
建筑科学   54篇
矿业工程   21篇
能源动力   43篇
轻工业   178篇
水利工程   26篇
石油天然气   9篇
武器工业   4篇
无线电   92篇
一般工业技术   160篇
冶金工业   1686篇
原子能技术   15篇
自动化技术   158篇
  2023年   17篇
  2022年   37篇
  2021年   43篇
  2020年   37篇
  2019年   18篇
  2018年   16篇
  2017年   26篇
  2016年   32篇
  2015年   30篇
  2014年   43篇
  2013年   56篇
  2012年   79篇
  2011年   79篇
  2010年   77篇
  2009年   81篇
  2008年   83篇
  2007年   92篇
  2006年   84篇
  2005年   51篇
  2004年   50篇
  2003年   45篇
  2002年   38篇
  2001年   44篇
  2000年   28篇
  1999年   55篇
  1998年   506篇
  1997年   307篇
  1996年   180篇
  1995年   102篇
  1994年   81篇
  1993年   99篇
  1992年   26篇
  1991年   12篇
  1990年   21篇
  1989年   10篇
  1988年   17篇
  1987年   10篇
  1986年   9篇
  1985年   8篇
  1983年   7篇
  1982年   9篇
  1981年   16篇
  1980年   19篇
  1978年   12篇
  1977年   60篇
  1976年   145篇
  1975年   14篇
  1974年   7篇
  1969年   6篇
  1955年   5篇
排序方式: 共有2995条查询结果,搜索用时 15 毫秒
1.
Presents the Satellite Communications Network Expert (SaNE), a knowledge-based aid designed to provide engineering support for fault diagnosis. The SaNE is composed of two elements: a satcom network model, which simulates the structure and functionality of a system based loosely upon a large military satcom network, and a diagnostic component, which uses knowledge- and model-based reasoning techniques to analyse system anomalies and diagnose possible causes for the alarms such networks generate. The development cycle is described, emphasising lessons learnt during development and testing and the advantages and disadvantages of the techniques applied. The goal of the SaNE project is primarily commercial acceptance rather than innovation. The authors illustrate how novel concepts can be implemented in a practical system without compromising this goal  相似文献   
2.
3.
4.
5.
Influence of the prenatal hypoinsulinaemia (streptozocin diabetes) on the behaviour of the offsprings of Wistar rats was studied from 1 to 20 postnatal days. In experimental pups there were slower weight increment, later eye opening, later development of elementary behavioural acts (grooming elements, rearing, sniffing), and later formation of complex behavioural patterns (investigation of an environment) than in the control offsprings of healthy females.  相似文献   
6.
Ancylostoma duodenale is still the dominant hookworm species in the Mediterranean area, India, China and Japan. In the present study, biopsied materials were taken from the small intestine of 30 patients infected only with A. duodenale and 12 cross matched controls. The results showed some pathological changes in severely infected cases. However, normal or insignificant changes were seen in the enzymatic activity of the intestinal mucosa.  相似文献   
7.
分析了汽车制动液罐注射件的结构特点,使用Moldflow软件对制品的注射成型过程进行CAE分析,确定了模具的浇注系统和成型工艺条件。模具为三板式点浇口结构,采用嵌件抽芯、斜导柱抽芯和液压抽芯相结合的方式实现模具的抽芯要求,并在此基础上完成了模具设计。  相似文献   
8.
Abdominoperineal resection following anterior resection   总被引:1,自引:0,他引:1  
A series of 11 patients undergoing abdoninoperineal resection for "suture line recurrence" following anterior resection is presented. Five-year survival is 10%. Technically, the procedure is difficult and major problems are encountered, including large blood loss and ureteral complications. These patients had an inadequate distal margin of resection at the time of anterior resection. The survival of this group of patients underscores the importance of making the correct judgment about anterior or abdominoperineal resection at the time of the initial presentation of the patient. The phrase "suture line recurrence" is a misnomer; all of these patients had advanced pelvic malignancy. If the adequacy of the distal margin is questionable or a distal margin of 5 cm cannot be obtained safely at the time of anterior resection, abdominoperineal resection should be performed, as the opportunity for cure of a recurrence should this rule be compromised is limited.  相似文献   
9.
In the past decade, capillary electrophoresis has demonstrated increasing utility for the quantitative analysis of single cells. New applications for the analysis of dynamic cellular properties demand sampling methods with sufficient temporal resolution to accurately measure these processes. In particular, intracellular signaling pathways involving many enzymes can be modulated on subsecond time scales. We have developed a technique to rapidly lyse an adherent mammalian cell using a single electrical pulse followed by efficient loading of the cellular contents into a capillary. Microfabricated electrodes were designed to create a maximum voltage drop across the flattened cell's plasma membrane at a minimum interelectrode voltage. The influence of the interelectrode distance, pulse duration, and pulse strength on the rate of cell lysis was determined. The ability to rapidly lyse a cell and collect and separate the cellular contents was demonstrated by loading cells with Oregon Green and two isomers of carboxyfluorescein. All three fluorophores were detected with a separation efficiency comparable to that of standards. Parallel comparison of electrical lysis to that produced by a laser-based lysis system revealed that the sampling efficiencies of the two techniques were comparable. Rapid cell lysis by an electrical pulse may increase the application of capillary electrophoresis to the study of cellular dynamics requiring fast sampling times.  相似文献   
10.
基于智能制造背景,分析了企业动态联盟下的工艺过程分级新策略。根据企业动态联盟的产品制造与生产方式,提出工艺过程分级策略,进一步构建生产准备资源及加工任务两者之间的映射关系,优化制造资源配置,该分级方式对提升生产效率、优化产品质量具有一定的作用。  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