全文获取类型
收费全文 | 704篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 6篇 |
金属工艺 | 1篇 |
建筑科学 | 2篇 |
轻工业 | 20篇 |
无线电 | 3篇 |
一般工业技术 | 2篇 |
冶金工业 | 669篇 |
自动化技术 | 2篇 |
出版年
2014年 | 2篇 |
2011年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 1篇 |
1999年 | 15篇 |
1998年 | 191篇 |
1997年 | 110篇 |
1996年 | 83篇 |
1995年 | 45篇 |
1994年 | 48篇 |
1993年 | 43篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 23篇 |
1976年 | 52篇 |
1975年 | 1篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有705条查询结果,搜索用时 0 毫秒
91.
92.
HF Bunn AJ Altman K Stangland SI Firshein B Forget GJ Schmidt RT Jones 《Canadian Metallurgical Quarterly》1978,2(6):531-540
Hemoglobins D-Los Angeles (beta 121 Gln) and Aida (alpha 64 Asn) were encountered in an Asian Indian, unassociated with any clinical manifestations. These hemoglobins had normal oxygen affinities and were stable to heat and isopropanol. The ratio of alpha chain synthesis to beta chain synthesis was close to unity. The identical change in isoelectric points of the two variants produced an interesting electrophoretic pattern. 相似文献
93.
Pharmacoradiography of the digestive system improves often accuracy of diagnostic information compared to conventional X-ray examinations. Pharmacoradiography should be used more often; the examiner has to be familiar with the principal effects and side effects of the pharmaceutica. The present paper gives a short summary about drugs and examination techniques most often used. 相似文献
94.
95.
The retinoid ligand 4-oxo-retinoic acid is a highly active modulator of positional specification 总被引:1,自引:0,他引:1
WW Pijnappel HF Hendriks GE Folkers CE van den Brink EJ Dekker C Edelenbosch PT van der Saag AJ Durston 《Canadian Metallurgical Quarterly》1993,366(6453):340-344
Retinoids (vitamin A and its metabolites) are suspected of regulating diverse aspects of growth, differentiation, and patterning during embryogenesis, but many questions remain about the identities and functions of the endogenous active retinoids involved. The pleiotropic effects of retinoids may be explained by the existence of complex signal transduction pathways involving diverse nuclear receptors of the retinoic acid receptor (RAR) and retinoid X receptor (RXR) families, and at least two types of cellular retinoic acid binding proteins (CRABP-I and -II). The different RARs, RXRs, and CRABPs have different expression patterns during vertebrate embryogenesis, suggesting that they each have particular functions. Another level at which fine tuning of retinoid action could occur is the metabolism of vitamin A to active metabolites, which may include all-trans-retinoic acid, all-trans-3,4-didehydroretinoic acid, 9-cis-retinoic acid, and 14-hydroxy-4,14-retroretinol. Formation of the metabolite all-trans-4-oxo-retinoic acid from retinoic acid was considered to be an inactivation pathway during growth and differentiation. We report here that, in contrast, 4-oxo-retinoic acid is a highly active metabolite which can modulate positional specification in early embryos. We also show that this retinoid binds avidly to and activates RAR beta, and that it is available in early embryos. The different activities of 4-oxo-retinoic acid and retinoic acid in modulating positional specification on the one hand, and growth and differentiation on the other, interest us in the possibility that specific retinoid ligands regulate different physiological processes in vivo. 相似文献
96.
BACKGROUND: A study was carried out to determine the extent to which asthma deaths are wrongly attributed to another cause on UK death certificates. METHODS: Deaths from all causes occurring anywhere in the UK were identified amongst 2382 subjects aged 16-64 years within three years of discharge following hospital treatment for asthma (ICD9 493) in hospitals in the South East Thames region. The deaths were reviewed by an expert panel to assess the proportion of asthma deaths identified by the panel which were attributed to another cause of death on the death certificate (false negatives). RESULTS: Eighty five deaths from all causes were identified in a mean follow up period of two years and three months. In 61 cases (72%) there was sufficient information for the expert panel to be confident about the cause of death. The panel identified 22 deaths from asthma, four of which were certified as non-asthma deaths (two as deaths from chronic obstructive pulmonary disease (COPD) and two as deaths from cardiovascular disease). The proportion of false negative death certificates was four of 22 (18%, 95% confidence interval (CI) 5 to 40). CONCLUSIONS: There is evidence that asthma deaths in the UK are wrongly certified as deaths from both chronic obstructive pulmonary disease and diseases of the cardiovascular system. 相似文献
97.
S van der Heide HF Kauffman AE Dubois JG de Monchy 《Canadian Metallurgical Quarterly》1997,52(9):921-927
This double-blind, placebo-controlled study investigated whether the application of an acaricide (Acarosan) on mattresses and on textile floor coverings in living rooms and bedrooms can contribute to improvement in lung function and airway hyperresponsiveness in 40 adult asthmatic patients sensitized to house-dust mite. In a second group of 19 patients who refused chemical intervention, the clinical effects of application of allergen-impermeable mattress encasings were studied. In all three treatment groups, Der p 1 levels in mattress dust were statistically significantly decreased after 12 months. However, this decrease was much greater in the group who received mattress encasings (final mean level 430 ng/g) than in groups with acaricide- or placebo-treated mattresses (final mean levels 1730 and 2100 ng/g, respectively). Treatment of textile floors with either Acarosan or placebo chemical caused a statistically significant decrease in the level of the house-dust-mite allergen Der p1 in floor dust. In the group with mattress encasings, no significant changes of floor dust Der p 1 were found. Airway hyperresponsiveness (as measured by the PC20 histamine) improved significantly in the mattress cover group after 6 months. The Acarosan group also showed a small but statistically significant improvement after 12 months. 相似文献
98.
Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a multifunctional cytokine and growth factor that has important roles in both pathological and physiological angiogenesis. VPF/VEGF induces vascular hyperpermeability, cell division, and other activities by interacting with two specific receptor tyrosine kinases, KDR/Flk-1 and Flt-1, that are selectively expressed on vascular endothelium. The signaling cascade that follows VPF/VEGF interaction with cultured endothelium is only partially understood but is known to result in increased intracellular calcium, activation of protein kinase C, and tyrosine phosphorylations of both receptors, phospholipase C-gamma (PLC-gamma) and phosphatidylinositol 3'-kinase. For many reasons, signaling events elicited in cultured endothelium may not mimic mediator effects on intact normal or tumor-induced microvessels in vivo. Therefore, we developed a system that would allow measurement of VPF/VEGF-induced signaling on intact microvessels. We used mouse mesentery, a tissue whose numerous microvessels are highly responsive to VPF/VEGF and that we found to express Flk-1 and Flt-1 selectively. At intervals after injecting VPF/VEGF i.p., mesenteries were harvested, extracted, and immunoprecipitated. Immunoblots confirmed that VPF/VEGF induced tyrosine phosphorylation of several proteins in mesenteric microvessels as in cultured endothelium: Flk-1; PLC-gamma; and mitogen-activated protein kinase. Similar phosphorylations were observed when mesentery was exposed to VPF/VEGF in vitro, or when mesenteries were harvested from mice bearing the mouse ovarian tumor ascites tumor, which itself secretes abundant VPF/VEGF. Other experiments further elucidated the VPF/VEGF signaling pathway, demonstrating phosphorylation of both PYK2 and focal adhesion kinase, activation of c-jun-NH2-kinase with phosphorylation of c-Jun, and an association between Flk-1 and PLC-gamma. In addition, we demonstrated translocation of mitogen-activated protein kinase to the cell nucleus in cultured endothelium. Taken together, these experiments describe a new model system with the potential for investigating signaling events in response to diverse mediators on intact microvessels in vivo and have further elucidated the VPF/VEGF signaling cascade. 相似文献
99.
100.