全文获取类型
收费全文 | 275篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 2篇 |
建筑科学 | 2篇 |
轻工业 | 4篇 |
无线电 | 1篇 |
一般工业技术 | 3篇 |
冶金工业 | 262篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2016年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2004年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 5篇 |
1998年 | 66篇 |
1997年 | 41篇 |
1996年 | 27篇 |
1995年 | 23篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 24篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有275条查询结果,搜索用时 0 毫秒
1.
2.
3.
(1) The effects of long term treatment with 3-acetylpyridine on the stability of enzymes towards heat and trypsin treatment were studied. (2) In the liver NAD or NADP provided a similar degree of protection against heat inactivation at 55 degrees C for 6-phosphogluconate dehydrogenase (24%), glyceraldehyde-3-phosphate dehydrogenase (24%) and malic enzyme (20%), low level of protection of lactate dehydrogenase (13%) but didn't affect acetylcholinesterase at all. In the muscle, however, there was substantial protection against heat inactivation by coenzyme of glyceraldehyde-3-phosphate dehydrogenase (52%), an intermediate level of protection of lactate dehydrogenase (25%), low level of protection of 6-phosphogluconate dehydrogenase (17%) and malic enzyme (17%) and almost no protection of acetylcholinesterase. (3) In the susceptibility towards trypsin a low but similar degree of protection for dehydrogenases by coenzymes was observed in the liver whereas in the muscle there was substantial protection against trypsin inactivation by NAD of glyceraldehyde-3-phosphate dehydrogenase, an intermediate level of protection of 6-phosphogluconate dehydrogenase and malic enzyme and very little protection of lactate dehydrogenase but no protection of acetylcholinesterase. Among enzymes tested, glyceraldehyde-3-phosphate dehydrogenase showed the greatest protection against heat and trypsin inactivation by NAD. (4) The results suggest that the effect of 3-acetylpyridine treatment on the stability of muscle glyceraldehyde-3-phosphate dehydrogenase appears to be quite specific and selective. 相似文献
4.
The Kjeldahl and Dumas (combustion) methods were compared in 11 laboratories analyzing samples of milk, skim milk powder, whole milk powder, whey protein concentrate, infant formula, casein, caseinate, 2 reference compounds (glycine and EDTA), and a secondary reference skim milk powder. The comparison was conducted by using international standards where applicable. Overall means were 8.818 g N/100 g by the Kjeldahl method and 8.810 g N/100 g by the Dumas method. No evidence was found for a consistent bias between methods that may be of concern in the trading of dairy produce. A review of more than 10 related trials revealed a lack of consensus in the bias between the 2 methods, suggesting that differences in methodology and sources of systematic error may be contributors. For samples containing > 2 g N/100 g, the Dumas relative repeatability and reproducibility standard deviations were consistently about 0.35 and 0.75%, respectively, whereas the corresponding Kjeldahl values declined generally with N content and were significantly larger. The Dumas precision characteristics may be due to the dominance of Leco analyzers in this trials, and in most other recent trials, rather than an inherent method attribute. Protein determination methods for dairy products need to be reviewed and updated. The Dumas method needs Codex Alimentarius status as a recognized test method. 相似文献
5.
JR Bearder VM Frydman P Gaskin IK Hatton WE Harvey J McMillan BO Phinney 《Canadian Metallurgical Quarterly》1976,39(2):178-183
Angiotensin II (A II) and analogues were tested for their ability to restore electrical and mechanical activity to cardiac muscle preparations in which the fast Na+ channels had been inactivated by partial depolarization (22-27 mM K+) or by tetrodotoxin (TTX). The partially depolarized or TTX-blocked preparations were chosen because under these conditions electrical and mechanical responses are primarily Ca2+ -dependent. In depolarized rabbit right atria, A II restored spontaneous mechanical and electrical activity (measured by both intracellular and extracellular recording techniques). The frequency of action potential discharge was concentration-dependent; the threshold concentration of A II was 10(-10) M, the ED50 was 8 X 10(-9) M, and the maximum effect was observed at 5 X 10(-8) M. In contrast, depolarized guinea pig atria were insensitive to A II, Sar1-angiotensin II, and des-Asp1-angiotensin II, even at concentrations as high as 10(-5) M. Rabbit papillary muscle (TTX-blocked), embryonic (18-day) chick heart (partially depolarized) and chick heart reaggregates (TTX-blocked) responded similarly to rabbit atria in that A II (9.6 X 10(-7) M) restored both electrical and mechanical activity. We found that in these preparations the action of A II was unaffected by propranolol (5.0 X 10(-6) M to 5.0 X 10(-5) M) but was blocked by Mn2+ (10(-3) M), D-600 (1 X 10(-7) g/ml) and the specific A II antagonists Sar1-Ala8-angiotensin II (P-113) (5.0 X 10(-5) M) and Sar1-Ile8-angiotensin II (5.28 X 10(-5) M). We conclude that the positive inotropic effect of A II on the myocardium is due to its ability to increase transmembrane ion movements in or through the cell membrane. The ability of Mn2+ and D-600 to block this effect suggests that this ion movement is via the so-called "slow channels." 相似文献
6.
用于测量GIS中瞬态外壳电压的电阻性阻抗分压器 总被引:6,自引:2,他引:4
设计了用于测量GIS中TEV的阻抗分压器及其测量系统 ;分析了该系统的特性 ,并对其刻度因数和阶跃响应进行了实测 ,在实验室和现场进行了应用。结果表明 ,该系统主要性能满足IEC6 132 1标准的要求 ,可以在工程中应用 相似文献
7.
8.
Expression of the third component of complement, C3, in regenerating limb blastema cells of urodeles 总被引:1,自引:0,他引:1
K Del Rio-Tsonis PA Tsonis IK Zarkadis AG Tsagas JD Lambris 《Canadian Metallurgical Quarterly》1998,161(12):6819-6824
In this study we have shown that complement component C3 is expressed in the regenerating tissue during urodele limb regeneration. C3 was expressed in the dedifferentiated regeneration blastema and in the redifferentiated limb tissues in the axolotl, Amblystoma mexicanum, and in Notophthalmus viridescens. This expression was verified by immunofluorescent staining using an Ab against axolotl C3 and by in situ hybridization with an axolotl C3 cDNA probe. In the early stages of regeneration C3 appeared to be equally present in all mesenchymal cells and in the wound epithelium, whereas in the later stages it was mainly expressed in the differentiating muscle cells. Since no expression was seen in the developing limb, it appears that the C3 expression was specific to the regeneration process. We then demonstrated by hybridization experiments that a blastema cell line of myogenic origin expresses C3. All these findings implicate C3 in the dedifferentiation process and may indicate a new role for this molecule in muscle differentiation. 相似文献
9.
Forty-one consecutive patients who underwent a revision microlumbar exploration for recurrent or persistent sciatica were reviewed retrospectively to analyse the operative findings and assess the clinical outcome following surgery. Thirty-three (80%) patients were found to have a recurrent intervertebral disc protrusion at the previous site, two patients had a disc herniation at a new site, one had severe perineural scarring, two had lateral recess stenosis, one patient had undergone previous exploration at an incorrect site and in two patients no cause for ongoing symptoms was found. Nineteen of the 33 patients with a re-prolapse presented with persistent or recurrent sciatica within 1 year of their first operation. The other 14 patients presented with a late re-prolapse (after 1 year) and their clinical outcome was better than for those patients with an early re-prolapse (12/14 vs 11/19 satisfactory result, respectively). The result of operating on patients with a late re-prolapse was comparable to the 80-95% satisfactory outcomes following primary lumbar microdiscectomy reported by other authors. 相似文献
10.
IK Temple RJ Gardner DO Robinson MS Kibirige AW Ferguson JD Baum JC Barber RS James JP Shield 《Canadian Metallurgical Quarterly》1996,5(8):1117-1121
Transient neonatal diabetes mellitus (TNDM) is a rare form of childhood diabetes which usually resolves in the first 6 months of life but which predisposes to type 2 diabetes of adult onset. We recently reported paternal uniparental isodisomy of chromosome 6 (UPD6) in two children with TNDM and proposed that there may be an imprinted gene important in the aetiology of diabetes on chromosome 6. We now describe two unrelated families which independently suggest that the gene is imprinted, is paternally expressed and maps to 6q22-q23. One family has a duplication while the other, with familial TNDM, shows linkage to a marker in this region. 相似文献