全文获取类型
收费全文 | 2326篇 |
免费 | 3篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 175篇 |
金属工艺 | 66篇 |
机械仪表 | 25篇 |
建筑科学 | 3篇 |
矿业工程 | 17篇 |
能源动力 | 8篇 |
轻工业 | 6篇 |
水利工程 | 22篇 |
石油天然气 | 62篇 |
无线电 | 21篇 |
一般工业技术 | 170篇 |
冶金工业 | 1644篇 |
原子能技术 | 58篇 |
自动化技术 | 45篇 |
出版年
2022年 | 11篇 |
2021年 | 12篇 |
2019年 | 11篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 33篇 |
2012年 | 23篇 |
2011年 | 20篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 18篇 |
2004年 | 27篇 |
2002年 | 12篇 |
2000年 | 17篇 |
1999年 | 34篇 |
1998年 | 416篇 |
1997年 | 262篇 |
1996年 | 176篇 |
1995年 | 101篇 |
1994年 | 89篇 |
1993年 | 107篇 |
1992年 | 20篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 22篇 |
1988年 | 19篇 |
1987年 | 26篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1982年 | 26篇 |
1981年 | 35篇 |
1980年 | 42篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 98篇 |
1976年 | 195篇 |
1975年 | 20篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1972年 | 10篇 |
1971年 | 11篇 |
1970年 | 14篇 |
1969年 | 13篇 |
排序方式: 共有2329条查询结果,搜索用时 0 毫秒
1.
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
2.
KhKh Sharafetdinov VA Meshcheriakova OA Plotnikova 《Canadian Metallurgical Quarterly》1998,86(3):30-33
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
3.
A model of the electronic structure of graphite-like carbon films, describing the semiconductor properties of this material, is presented. Spectra of optical constants of microcrystalline carbon films in the region λ = 0.4–8.0 μm were studied by the spectral ellipsometry and IR reflection methods. A number of distinctive features of the spectra, associated with both the appearance of C---C- and C---Hn-type bonds and direct energy gaps, were found. Analysis of the optical data using the proposed model makes possible a common interpretation of our results and literature data. Values of a parameter Θ, which is an averaged qualitative parameter of structural distortions within carbon microcrystallites as compared with crystalline graphite, are determined from comparison of theoretical results and experimental data. 相似文献
4.
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
5.
NI Koval'chuk FN Shubin VA Khoroshko FN Sheverdina TT Tarasenko NG Kosheleva 《Canadian Metallurgical Quarterly》1997,(5):88-91
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
6.
7.
Activation energy of electron-stimulated quenching of the photoluminescence of n-type porous silicon
The degradation of photoluminescence of porous silicon by kilovolt electrons and the mechanism and activation energy of this
process have been investigated. Quantitative relations between the integral intensity of the photoluminescence and the irradiation
dose and substrate temperature are obtained. The mechanism of the process is discussed and its activation energy is determined.
Pis’ma Zh. Tekh. Fiz. 23, 44–50 (September 26, 1997) 相似文献
8.
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
9.
Polymorphous low-grade adenocarcinoma is an unusual tumor that has been described as occurring in the minor salivary glands, particularly of the palate. To our knowledge, there is only one previous report that has documented the occurrence of this type of lesion in the major salivary glands. We describe an elderly patient with polymorphous low-grade adenocarcinoma arising in the parotid gland that was originally diagnosed as carcinoma ex pleomorphic adenoma. 相似文献
10.