全文获取类型
收费全文 | 2818篇 |
免费 | 0篇 |
专业分类
化学工业 | 16篇 |
建筑科学 | 1篇 |
矿业工程 | 1篇 |
轻工业 | 5篇 |
无线电 | 6篇 |
一般工业技术 | 2篇 |
冶金工业 | 2787篇 |
出版年
2020年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2010年 | 1篇 |
2008年 | 2篇 |
2005年 | 1篇 |
2003年 | 3篇 |
2000年 | 3篇 |
1999年 | 84篇 |
1998年 | 913篇 |
1997年 | 489篇 |
1996年 | 333篇 |
1995年 | 183篇 |
1994年 | 139篇 |
1993年 | 148篇 |
1992年 | 17篇 |
1991年 | 43篇 |
1990年 | 32篇 |
1989年 | 33篇 |
1988年 | 33篇 |
1987年 | 44篇 |
1986年 | 36篇 |
1985年 | 20篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 56篇 |
1976年 | 133篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2818条查询结果,搜索用时 0 毫秒
31.
Independent intracellular activation of any one of the five identified neurones elicits a behavioral act of pneumostome closing. Similar closing is evoked by adequate stimulation of different modalities. Comparison of unconditioned reflex properties and characteristics of responses of the studied cells leads to the conclusion that neurones under discussion are command elements for the unconditioned reflex. Command neurones respond to all sensory stimuli which can evoke reflex closing. There is a lot of synchronous EPSPs in their spontaneous activity, but no action potentials. A spike discharge of command neurones evoked by an adequate stimulus always precedes the effector movements but there is no action potentials during the pneumostome closing. Conclusion is made that the functional role of command neurones in the unconditioned reflex arc consists in evaluating the sensory input and in triggering motor programmes. 相似文献
32.
Modern methods of semeiological detection of bronchiogenic cancer are discussed in the light of experience gained in a hospital chest surgery centre. Emphasis is laid on the advantages offered by new advances in nuclear diagnosis and bronchial endoscopy. The limitations of exploratory thoractomy are explained. Attention is drawn to the by no means inconsiderable number of cases in which early knowledge of the nature of the process could not be obtained. A series of illustrative cases are presented. 相似文献
33.
Hybrid magnetic nanostructures with high coercivity have immense application potential in various fields. Nickel (Ni) electrodeposited inside Cobalt (Co) nanotubes (a new system named Ni @ Co nanorods) were fabricated using a two-step potentiostatic electrodeposition method. Ni @ Co nanorods were crystalline, and they have an average diameter of 150 nm and length of ~15 μm. The X-ray diffraction studies revealed the existence of two separate phases corresponding to Ni and Co. Ni @ Co nanorods exhibited a very high longitudinal coercivity. The general mobility-assisted growth mechanism proposed for the growth of one-dimensional nanostructures inside nano porous alumina during potentiostatic electrodeposition is found to be valid in this case too. 相似文献
34.
35.
PM Murphy 《Canadian Metallurgical Quarterly》1997,11(2):246-249
TEE is an expensive but useful intraoperative diagnostic strategy for cardiac surgical procedures. It can alter surgical management with tremendous potential benefits to the patient. It also has the potential to avoid unnecessary surgery and reduce the risk of complications such as reoperation, thromboembolism, and stroke. As with any new technology, the indications for its use must be evaluated on the basis of cost, benefits, and efficacy to determine the true value and cost-effectiveness in a particular application. Based on the information presented in this report, it can be concluded that TEE is a cost-effective strategy for valvular and congenital heart repairs. Current data are very convincing that TEE has the potential to be cost-effective in reducing the risk of stroke in selected populations of cardiac surgical patients. As experience with the use of TEE in its various applications increases and the technology itself continues to improve, it will undoubtedly become a more valuable and cost-effective strategy for cardiac surgery. 相似文献
36.
37.
38.
The evidence for and against the prophylactic use of anticonvulsants and antibiotics in head injury is reviewed. There is a lack of blinded placebo-controlled trials in this area. On balance there is no compelling evidence to support the use of either anticonvulsant or antibiotic prophylaxis in head injury, with the possible exception of antibiotic prophylaxis in compound depressed skull fractures and penetrating brain injuries. 相似文献
39.
40.