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   1947篇
  免费   6篇
电工技术   17篇
化学工业   48篇
金属工艺   32篇
机械仪表   23篇
建筑科学   2篇
矿业工程   10篇
能源动力   2篇
轻工业   11篇
水利工程   10篇
石油天然气   21篇
无线电   24篇
一般工业技术   126篇
冶金工业   1563篇
原子能技术   41篇
自动化技术   23篇
  2021年   9篇
  2020年   7篇
  2019年   10篇
  2018年   18篇
  2017年   17篇
  2016年   24篇
  2015年   6篇
  2014年   14篇
  2013年   20篇
  2012年   12篇
  2011年   15篇
  2010年   16篇
  2009年   10篇
  2008年   8篇
  2007年   16篇
  2006年   9篇
  2005年   6篇
  2004年   7篇
  2003年   8篇
  2001年   12篇
  1999年   26篇
  1998年   414篇
  1997年   255篇
  1996年   170篇
  1995年   105篇
  1994年   77篇
  1993年   115篇
  1992年   16篇
  1991年   15篇
  1990年   11篇
  1989年   13篇
  1988年   16篇
  1987年   18篇
  1986年   9篇
  1985年   8篇
  1984年   4篇
  1983年   5篇
  1982年   18篇
  1981年   26篇
  1980年   30篇
  1979年   4篇
  1978年   8篇
  1977年   100篇
  1976年   186篇
  1975年   12篇
  1972年   6篇
  1970年   4篇
  1967年   4篇
  1966年   3篇
  1965年   3篇
排序方式: 共有1953条查询结果,搜索用时 234 毫秒
1.
Russian Journal of Non-Ferrous Metals - This article is devoted to the influence of sodium lignosulfonate (SL), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate...  相似文献   
2.
Vascular injuries may occur as complications of elbow dislocation and usually involve the brachial artery. A case report is presented in which only the radial artery was compromised as a result of the dislocation.  相似文献   
3.
The paper analyzes left ventricular structure-fraction relationships in the development of postinfarct aneurysm. The altered internal architectonics induces to systemic hemodynamic changes, drastically elevated intraventricular pressure. This is caused by to the dysfunction of the papillary-trabecular complex in the left ventricular cavity, which in turn. This leads to the fact that the heart work as a positive-displacement pump, by losing its capacity as a centrifugal component, by making the myocardium require additional energy expenditures, which in turn appears as varying heart failure. This investigation is of definite practical value in developing adequate correction methods for postinfarct aneurysm which can occur with the retained or formed certain ratios of cardiac structures.  相似文献   
4.
5.
The possibilities of using influenza A (Leningrad) 385/80 (H3N2) virus matrix protein-specific FITC-labeled D8 monoclonal antibodies in immunofluorescence assays were investigated. The virus antigen accumulation was detected in chorioallantoic cells of chick embryos. Exhibiting the type-specific properties, the fluorescent antibodies stain the perinuclear space, cytoplasmic membrane, and granular structures in the cytoplasm of infected cells. The haemagglutination test tires in the corresponding specimens were at least 1:16.  相似文献   
6.
Echo-planar techniques in MRI use a rapidly oscillating frequency-encoding gradient with the potential to produce peripheral nerve stimulation. To evaluate the incidence, type, and location of stimulation in a commercial whole-body scanner, we studied two groups: (a) 173 consecutive individuals scanned by echo-planar imaging for other purposes and (b) seven subjects who were scanned with an extensive set of 36 echo-planar sequences (with prompting after each scan to report any peripheral nerve stimulation) to test the effects of various parameters. Although only 5% of group A reported symptoms of peripheral nerve stimulation, all in group B experienced some type of stimulation, dependent primarily on direction of the oscillating gradient and location of the body within the gradient coil. Maximum stimulation typically occurred 30 to 40 cm from isocenter in the region of maximum dB/dt. Generally, y gradients produced truncal stimulation, and x gradients produced stimulation in the head. When hands were clasped over the abdomen, a tingling in the hands occasionally was felt. Patients should be instructed to keep their hands apart.  相似文献   
7.
The results of the comparative study of the phenotypical properties and the plasmid profile of 63 strains of salmonellae, belonging to 44 serotypes of groups B, C1, C2, C3, D, E1, E4, F. The study revealed that strains of different serotypes had their individual plasmid profile. Strains of the same serotype of salmonellae isolated from similar sources had an identical plasmid profile, while strains isolated from different sources differed in their plasmid profiles, though they might have a similar phenotype. Plasmid analysis was shown to be an effective method for the intraspecific typing of rarely isolated Salmonella serotypes and suitable for use as the basis of the microbiological monitoring of salmonellae.  相似文献   
8.
OBJECTIVE: To evaluate the discrepancy index between the clinical and histological diagnosis and the prevalence of epithelial dysplasia and carcinoma in 45 patients with potentially malignant epithelial oral lesions (PMEL). PATIENTS AND METHODS: We submitted 45 patients with PMEL to clinical examination and obtained a biopsy from each. The results of histological diagnosis were compared to the clinical diagnosis. RESULTS: Clinical diagnosis showed that the most common PMEL was leukoplakia followed by lichen planus and by actinic cheilitis associated with leukoplakia. The most common site was the buccal mucosa. Histological diagnosis revealed that 46.7% of the PMEL were lichen planus. The discrepancy index between clinical and histological diagnosis was 24.4%. The higher discrepancy index occurred among leukoplakias. The prevalence of epithelial dysplasia and carcinoma was 17.8%. CONCLUSIONS: We conclude that all PMEL should be submitted to a microscopic analysis because the discrepancy between clinical and histological diagnosis was present in a quarter of these lesions. Otherwise, the epithelial dysplasia and carcinoma were more frequent in the leukoplakias.  相似文献   
9.
10.
Controlling and diagnostic processes in the bioengineering artificial clearance systems despite of the procedures applied, their functional use and design seem to occur in the artificial organs, each of them consists of controlling and actuating processors ensuring their homogeneous (material, energy-producing, informational) or combined interaction with the patient's body. Centralized control over artificial clearance is proposed by using universal controlling processes which are informationally connected with the operator, the central computer and other controlling processes of the bioengineering system.  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