全文获取类型
收费全文 | 616篇 |
免费 | 6篇 |
国内免费 | 4篇 |
专业分类
综合类 | 2篇 |
化学工业 | 45篇 |
金属工艺 | 19篇 |
机械仪表 | 8篇 |
建筑科学 | 3篇 |
矿业工程 | 1篇 |
轻工业 | 8篇 |
水利工程 | 1篇 |
石油天然气 | 10篇 |
无线电 | 21篇 |
一般工业技术 | 35篇 |
冶金工业 | 457篇 |
原子能技术 | 2篇 |
自动化技术 | 14篇 |
出版年
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 121篇 |
1997年 | 80篇 |
1996年 | 59篇 |
1995年 | 31篇 |
1994年 | 23篇 |
1993年 | 29篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1977年 | 32篇 |
1976年 | 62篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有626条查询结果,搜索用时 437 毫秒
81.
82.
Intracerebral infection of mice aged 2-3 days with hepatitis C virus (HCV) from chronically infected suckling mouse brain cultures and porcine embryo cells resulted in the death of animals after 12-14 days. Repeated passages of HCV in animals decreased the incubation period to just 3-4 days. Blood serum of surviving mice collected during the 4th week postinfection contained antiHCV antibodies detected by enzyme immunoassay and hemagglutination inhibition test. The results are proof of creation of a new in vivo model of experimental HCV infection. 相似文献
83.
A technique of the optimization of the pultrusion process for rods with a large diameter with the use of methods of mathematical
modeling is described. An example of the search for the optimum technological parameters for the pultrusion of a glass-plastic
rod with a diameter of 80 mm is presented. 相似文献
84.
The report contains the results of clinico-dynamic studies of mental disorders in patients with Schilder's leukoencephalitis and subacute sclerosing panencephalitis after van-Bogart. The authors come to the conclusion that only parallel comparisons of the psychopathological symptomatology with focal neurological signs and a simultaneous study of the EEG and other paraclinical indices may facilitate the differential diagnosis of encephalitis. 相似文献
85.
86.
87.
88.
Plasmid pBS195, detected in a strain of Lactobacillus sp. isolated from long-living persons, has a broad host range, including Gram-positive and Gram-negative microorganisms [1]. Plasmid-harboring colonies of the strain Escherichia coli HB101 give a color reaction with catechol. This indicates that genes mediating the activity of oxygenase are present in this plasmid. The high activity level of this enzyme, mediated by pBS195, and substrate specificity, which has not bee detected in any known metapyrocatechases, were found in cells of E. coli. Hybridization with a 32P-labeled fragment containing the NahC gene revealed a region of homology with a 1.6-kb EcoR I- BamH I fragment of plasmid pBS195. Deletion variants of this plasmid that lost oxygenase activity confirmed the location of the oxygenase gene in this region. The gene responsible for oxygenase activity in the plasmid was cloned on the pUC19 vector in E. coli cells. The expression of the cloned gene is controlled by the lac promoter of this vector. Physical, hybridization, and deletion analyses as well as analysis of polypeptides, which are synthesized in E. coli mini-cells, showed that this activity requires the participation of a polypeptide with molecular mass of 34 kDa. 相似文献
89.
We analyzed 79 consecutive patients with aneurysms and found a patient who lacked type III collagen. Collagen was extracted from the skin, and the lack of type III collagen was determined by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Only 1 of the 79 patients was found to lack type III collagen. This patient was a 55-year-old man who had sustained an abdominal aortic aneurysm and aortic dissection. He did not show any of the typical clinical symptoms of Ehlers-Danlos syndrome type IV, such as hyperextensible skin and joints. He had none of the usual risk factors nor any clear family history of the syndrome. Furthermore, his collagen fibrils demonstrated a homogeneous appearance. This case may represent a new form of type III collagen deficiency. 相似文献
90.
We suggest that toroidal structures in the state of psi-condensation of DNA may be caused by anisotropy on a meso-scale of several thousand A, the conformation of a DNA-molecule being determined by its elasticity and neutralization of phosphate charge. We model a molecule of B-DNA on an anisotropic elastic rod subject to a torque, and make the numerical simulation of the model that reveals that under appropriate conditions, which may be effected in experimental setting by changing the concentration of polymeric solutions, there are toroidal structures having the size of a few persistence lengths, in agreement with the experimental data. On changing the elastic modulii or characteristics of the counterion layer, we see the toroidal structures turn into the spherical ones. To understand the function of anisotropy it would be interesting to investigate the Z-DNA as regards psi-condensation. 相似文献