全文获取类型
收费全文 | 83篇 |
免费 | 1篇 |
专业分类
化学工业 | 4篇 |
金属工艺 | 1篇 |
机械仪表 | 3篇 |
建筑科学 | 2篇 |
能源动力 | 5篇 |
轻工业 | 3篇 |
水利工程 | 1篇 |
无线电 | 12篇 |
一般工业技术 | 11篇 |
冶金工业 | 34篇 |
原子能技术 | 2篇 |
自动化技术 | 6篇 |
出版年
2019年 | 1篇 |
2018年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1967年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有84条查询结果,搜索用时 15 毫秒
51.
52.
Helmke SM Yen CY Cios KJ Nunley K Bristow MR Duncan MW Perryman MB 《Analytical chemistry》2004,76(6):1683-1689
We have developed a novel method for quantifying protein isoforms, in both relative and absolute terms, based on MALDI-TOF mass spectrometry. The utility of the approach is demonstrated by quantifying the alpha and beta protein isoforms of myosin heavy chain (MyHC) in human atrial tissue. Alpha-MyHC (726-741) and beta-MyHC (724-739) were identified as isoform-specific tryptic peptides. A calibration curve was constructed by plotting ion current ratios against molar ratios of the two peptides prepared synthetically. MyHC was digested by trypsin and the ion current ratio determined for the two tryptic peptides. The ion current ratio was converted to the peptide ratio and hence the isoform ratio by reference to the standard curve. The accuracy of the method was confirmed by a comparison between these results and those determined by an established method of MyHC isoform ratio determination. So that the molar ratio could be converted to absolute values, a third peptide, an analogue of the two peptides being measured, was synthesized for use as an internal standard (IS). The measured ion current ratios of synthetic alpha-MyHC (726-741), beta-MyHC (724-739), and IS peptides were used to generate standard curves. A known quantity of the IS was added to the MyHC digests. The measured ion current ratios were converted to the actual quantities of the isoform-specific peptides and hence the actual quantity of each protein isoform by reference to the standard curves. This method is of general applicability, especially when isoform quantification is required. 相似文献
53.
The key aim of this paper is to examine strategic pathways to low carbon personal transport in Britain and to compare these with the current trajectory of transport policy. A 2050 baseline was established using trend information, forecasts and best evidence from the literature on response to policy intervention. A range of strategies are tested including: technological development, pricing, public transport and soft measures. We conclude that even dramatic technological advance cannot meet the more stringent targets for carbon reduction in the absence of considerable behavioural change. The most promising combinations of measures involve clear price signals to encourage both a reduction in the use of motorised transport and the development and purchase of more efficient vehicles; decarbonisation of public transport and facilitating measures to enhance access whilst reducing the need for motorised travel. 相似文献
54.
BD Lowes W Minobe WT Abraham MN Rizeq TJ Bohlmeyer RA Quaife RL Roden DL Dutcher AD Robertson NF Voelkel DB Badesch BM Groves EM Gilbert MR Bristow 《Canadian Metallurgical Quarterly》1997,100(9):2315-2324
Using quantitative RT-PCR in RNA from right ventricular (RV) endomyocardial biopsies from intact nonfailing hearts, and subjects with moderate RV failure from primary pulmonary hypertension (PPH) or idiopathic dilated cardiomyopathy (IDC), we measured expression of genes involved in regulation of contractility or hypertrophy. Gene expression was also assessed in LV (left ventricular) and RV free wall and RV endomyocardium of hearts from end-stage IDC subjects undergoing heart transplantation or from nonfailing donors. In intact failing hearts, downregulation of beta1-receptor mRNA and protein, upregulation of atrial natriuretic peptide mRNA expression, and increased myocyte diameter indicated similar degrees of failure and hypertrophy in the IDC and PPH phenotypes. The only molecular phenotypic difference between PPH and IDC RVs was upregulation of beta2-receptor gene expression in PPH but not IDC. The major new findings were that (a) both nonfailing intact and explanted human ventricular myocardium expressed substantial amounts of alpha-myosin heavy chain mRNA (alpha-MHC, 23-34% of total), and (b) in heart failure alpha-MHC was downregulated (by 67-84%) and beta-MHC gene expression was upregulated. We conclude that at the mRNA level nonfailing human heart expresses substantial alpha-MHC. In myocardial failure this alteration in gene expression of MHC isoforms, if translated into protein expression, would decrease myosin ATPase enzyme velocity and slow speed of contraction. 相似文献
55.
LS Zisman K Asano DL Dutcher A Ferdensi AD Robertson M Jenkin EW Bush T Bohlmeyer MB Perryman MR Bristow 《Canadian Metallurgical Quarterly》1998,98(17):1735-1741
BACKGROUND: The regulation and interaction of ACE and the angiotensin II (Ang II) type I (AT1) receptor in the failing human heart are not understood. METHODS AND RESULTS: Radioligand binding with 3H-ramiprilat was used to measure ACE protein in membrane preparations of hearts obtained from 36 subjects with idiopathic dilated cardiomyopathy (IDC), 8 subjects with primary pulmonary hypertension (PPH), and 32 organ donors with normal cardiac function (NF hearts). 125I-Ang II formation was measured in a subset of hearts. Saralasin (125I-(Sar1,Ile8)-Ang II) was used to measure total Ang II receptor density. AT1 and AT2 receptor binding were determined with the AT1 receptor antagonist losartan. Maximal ACE binding (Bmax) was 578+/-47 fmol/mg in IDC left ventricle (LV), 713+/-97 fmol/mg in PPH LV, and 325+/-27 fmol/mg in NF LV (P<0.001, IDC or PPH versus NF). In IDC, PPH, and NF right ventricles (RV), ACE Bmax was 737+/-78, 638+/-137, and 422+/-49 fmol/mg, respectively (P=0.02, IDC versus NF; P=0.08, PPH versus NF). 125I-Ang II formation correlated with ACE binding sites (r=0.60, P=0.00005). There was selective downregulation of the AT1 receptor subtype in failing PPH ventricles: 6.41+/-1.23 fmol/mg in PPH LV, 2.37+/-0.50 fmol/mg in PPH RV, 5.38+/-0.53 fmol/mg in NF LV, and 7.30+/-1.10 fmol/mg in NF RV (P=0.01, PPH RV versus PPH LV; P=0.0006, PPH RV versus NF RV). CONCLUSIONS: ACE binding sites are increased in both failing IDC and nonfailing PPH ventricles. In PPH hearts, the AT1 receptor is downregulated only in the failing RV. 相似文献
56.
Bristow A.D. Astratov V.N. Shimada R. Culshaw I.S. Skolnick M.S. Whittaker D.M. Tahraoui A. Krauss T.F. 《Quantum Electronics, IEEE Journal of》2002,38(7):880-884
Strong resonant polarization conversion is observed in the reflectivity properties of one-dimensional (1-D) lattices of air trenches deeply etched in AlGaAs surface waveguides. The symmetry properties and the magnitudes of the observed effects are found to be in good agreement with the results of scattering matrix calculations 相似文献
57.
S Bristow 《Canadian Metallurgical Quarterly》1976,72(23):884-887
58.
AF Bristow 《Canadian Metallurgical Quarterly》1993,11(7):301-305
Whilst insulin is a spectacularly successful drug for the management of diabetes mellitus, it remains difficult to mimic the physiological pattern of insulin secretion, even using the various quick-acting and insoluble formulations that are available. The introduction of recombinant-DNA technology to the manufacture of therapeutic insulin has made the rational design and production of insulin analogues with altered pharmacokinetic and pharmacological properties possible. Such analogues include 'monomeric' insulins, which do not form the insulin-zinc hexamer in solution and are absorbed more rapidly from the injection site, and long-acting insulins, which are absorbed very slowly at physiological pH. Many of these analogues are being tested clinically, and it is possible that the next generation of insulin therapy will be various combinations of rationally designed insulin analogues produced by industrial biotechnology. 相似文献
59.
MR Bristow WA Minobe MV Raynolds JD Port R Rasmussen PE Ray AM Feldman 《Canadian Metallurgical Quarterly》1993,92(6):2737-2745
Heart failure in humans is characterized by alterations in myocardial adrenergic signal transduction, the most prominent of which is down-regulation of beta 1-adrenergic receptors. We tested the hypothesis that down-regulation of beta 1-adrenergic receptors in the failing human heart is related to decreased steady-state levels of beta 1 receptor mRNA. Due to the extremely low abundance of beta 1 receptor mRNA, measurements were possible only by quantitative polymerase chain reaction (QPCR) or by RNase protection methods. Because the beta 1 receptor gene is intronless and beta 1 receptor mRNA abundance is low, QPCR yielded genomic amplification in total RNA, and mRNA measurements had to be performed in poly (A)(+)-enriched RNA. By QPCR the concentration of beta 1 receptor mRNA varied from 0.34 to 7.8 x 10(7) molecules/microgram poly(A)(+)-enriched RNA, and the assay was sensitive to 16.7 zeptomol. Using 100-mg aliquots of left ventricular myocardium obtained from organ donors (nonfailing ventricles, n = 12) or heart transplant recipients (failing ventricles, n = 13), the respective beta 1 mRNA levels measured by QPCR were 4.2 +/- 0.7 x 10(7)/micrograms vs. 2.10 +/- 0.3 x 10(7)/micrograms (P = 0.006). In these same nonfailing and failing left ventricles the respective beta 1-adrenergic receptor densities were 67.9 +/- 6.9 fmol/mg vs. 29.6 +/- 3.5 fmol/mg (P = 0.0001). Decreased mRNA abundance in the failing ventricles was confirmed by RNase protection assays in total RNA, which also demonstrated a 50% reduction in beta 1 message abundance. We conclude that down-regulation of beta 1 receptor mRNA contributes to down-regulation of beta 1 adrenergic receptors in the failing human heart. 相似文献
60.
Macroinvertebrate populations associated with Myriophyllum exalbescens, Potamogeton richardsonii, and Vallisneria americana were compared with those on plastic ‘plants’ similar in morphology to P. richardsonii. The density of organisms varied according to macrophyte species (Myriophyllum ? Potamogeton > Vallisneria). The plastic imitations did not differ significantly from Potamogeton in the total numbers of macrophytes they harboured at two different sampling periods during the growing season. A similar macroinvertebrate species composition occurred in association with the three plant species and with the artificial substrates. 相似文献