全文获取类型
收费全文 | 505篇 |
免费 | 1篇 |
专业分类
综合类 | 1篇 |
化学工业 | 1篇 |
机械仪表 | 1篇 |
轻工业 | 1篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
冶金工业 | 500篇 |
出版年
2019年 | 1篇 |
2016年 | 1篇 |
2013年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
1999年 | 15篇 |
1998年 | 149篇 |
1997年 | 87篇 |
1996年 | 76篇 |
1995年 | 30篇 |
1994年 | 28篇 |
1993年 | 32篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1977年 | 12篇 |
1976年 | 16篇 |
排序方式: 共有506条查询结果,搜索用时 15 毫秒
111.
Cda S Lacaz MS Vidal CN Pereira EM Heins-Vaccari NT de Melo N Sakai-Valente GL Arriagada 《Canadian Metallurgical Quarterly》1997,39(3):141-144
The shape of the acromion is strongly associated with impingement syndrome and with rotator cuff tears. It is notoriously difficult to image the acromion with conventional radiography. We have developed MRI techniques to depict the acromion in its longitudinal axis. Furthermore, we have measured the subacromial space in both external and internal rotation. In previous studies, three types of acromial shape have been described with the type III or hooked acromion being present in 66% of cases with rotator cuff tears. We studied 31 normal shoulders in 29 people using MRI. Within this population aged 24-36 years, mean age 31 years, no type III acromions were found. Twenty-one were type I (67.7%) and 10 were type II (32.3%). In addition, we found no difference in subacromial height in external or internal rotation. Low rates of intra- and interobserver error were found. These results imply that the hooked acromion is not present in the normal population and is, therefore, likely to be an acquired abnormality. 相似文献
112.
To examine the relation between fetal development and plasma concentrations of fibrinogen and factor VII in adult life we followed up 202 men and women, now aged around 50 years, who had been measured in detail at birth. Plasma concentrations of fibrinogen were related to weight and abdominal circumference at birth. In men, after adjustment for cigarette smoking and current obesity, plasma concentrations of fibrinogen fell by 0.12 g/l (95% CI 0.05-0.19) for each pound increase in birthweight and by 0.10 g/l (95% CI 0.03-0.17) for each inch increase in abdominal circumference. In contrast, analysis of the data for women showed no statistically significant relation between plasma fibrinogen concentration and weight or abdominal circumference at birth. No relation was seen between concentrations of factor VII and measurements made at birth in either sex. These findings suggest that, in men, reduced growth of the liver in fetal life has a long-term influence on fibrinogen metabolism. 相似文献
113.
Increased levels of the endothelial markers soluble E-selectin (P = 0.011), soluble thrombomodulin (P < 0.0001) and von Willebrand factor (VWF, P < 0.0001) were found in 116 patients with ischaemic heart disease compared to an equal number of age- and sex-matched asymptomatic controls. In a multivariate analysis of the markers versus the major risk factors for atherosclerosis, VWF correlated with total cholesterol (P = 0.002) and E-selectin with sex (lower in women, P = 0.004) and triglycerides (P = 0.007). The data point to profound differences in the release mechanisms of these three endothelial cell products and suggests that further studies into the roles of these molecules in coronary artery disease are warranted. 相似文献
114.
115.
Transforming growth factor-beta (TGF-beta) is secreted by many cell types as part of a large latent complex composed of three subunits: TGF-beta, the TGF-beta propeptide, and the latent TGF-beta binding protein (LTBP). To interact with its cell surface receptors, TGF-beta must be released from the latent complex by disrupting noncovalent interactions between mature TGF-beta and its propeptide. Previously, we identified LTBP-1 and transglutaminase, a cross-linking enzyme, as reactants involved in the formation of TGF-beta. In this study, we demonstrate that LTBP-1 and large latent complex are substrates for transglutaminase. Furthermore, we show that the covalent association between LTBP-1 and the extracellular matrix is transglutaminase dependent, as little LTBP-1 is recovered from matrix digests prepared from cultures treated with transglutaminase inhibitors. Three polyclonal antisera to glutathione S-transferase fusion proteins containing amino, middle, or carboxyl regions of LTBP-1S were used to identify domains of LTBP-1 involved in cross-linking and formation of TGF-beta by transglutaminase. Antibodies to the amino and carboxyl regions of LTBP-1S abrogate TGF-beta generation by vascular cell cocultures or macrophages. However, only antibodies to the amino-terminal region of LTBP-1 block transglutaminase-dependent cross-linking of large latent complex or LTBP-1. To further identify transglutaminase-reactive domains within the amino-terminal region of LTBP-1S, mutants of LTBP-1S with deletions of either the amino-terminal 293 (deltaN293) or 441 (deltaN441) amino acids were expressed transiently in CHO cells. Analysis of the LTBP-1S content in matrices of transfected CHO cultures revealed that deltaN293 LTBP-1S was matrix associated via a transglutaminase-dependent reaction, whereas deltaN441 LTBP-1S was not. This suggests that residues 294-441 are critical to the transglutaminase reactivity of LTBP-1S. 相似文献
116.
The usual features of non-Hodgkin lymphomas (NHL) of the mucosa-associated lymphoid tissue (MALT) include monocytoid B-cell proliferation, and chronic inflammatory precursor lesions. Despite a reputation of being indolent, NHL of the MALT may disseminate to other MALT areas, and raise difficult therapeutic questions. We report a case of gastric NHL of the MALT whose evolution, despite an initial surgical treatment considered radical, was noticeable for a well documented breast relapse. 相似文献
117.
118.
CN Christakos 《Canadian Metallurgical Quarterly》1997,78(6):3453-3459
This study considers the possibility of using coherence analysis for detection and measurement of synchrony (correlations) in large neural populations, applied to activities that are relatively easy to record in parallel. Mathematical analysis and computer simulations are used to examine the behavior of the coherence function between both unitary and population-aggregate activity (UTA coherence) and the aggregate activities of two populations (ATA coherence). The results indicate that for a large population showing partial correlations, the UTA coherence function is almost zero at all frequencies for the uncorrelated units. However, unless the synchrony is very restricted, its value is nonzero (i.e., statistically significant by common criteria) at each frequency of synchrony for the units that show correlations to other units. Moreover, this value is indicative of the strength of synchrony for any given unit. These properties enable the identification of the correlated units in a sample of unit/population activities simultaneously recorded in a series of experiments, and hence the detection of synchrony. The extent of synchrony can then be estimated as the fraction of such units in the sample, whereas the values of the UTA coherences in the sample can be used to estimate the strength and its distribution within the population. Similarly, the ATA coherence function is generally nonzero (significant) at the frequencies where there are correlations between members of two large populations. This enables the easy detection of such correlations from simultaneously recorded population activities. However, this function is a very sensitive index of synchrony and even shows saturation effects. It may therefore be used as a general measure of synchrony only under restricted conditions. 相似文献
119.
DM Gibb SE MacDonagh PA Tookey T Duong A Nicoll DJ Goldberg CN Hudson CS Peckham AE Ades 《Canadian Metallurgical Quarterly》1997,11(7):F53-F58
OBJECTIVES: To describe the uptake of interventions to reduce mother-to-child transmission of HIV infection. DESIGN: Voluntary confidential reporting of HIV infection in pregnancy and childhood; telephone interview with key professionals in all London maternity units. SUBJECTS AND SETTING: HIV-infected pregnant women and children in the United Kingdom and Ireland. MAIN OUTCOME MEASURES: Trends in breastfeeding, use of zidovudine, mode of delivery and terminations of pregnancy. RESULTS: Between 1990 and 1995, 14 (4%) out of 314 women diagnosed with HIV infection before delivery breastfed compared with 109 (77%) out of 142 diagnosed after delivery. Since 1994, zidovudine use has increased in each 6-month period (14, 39, 67, and 75%; chi 2 = 17.5, P < 0.001), although in 1995 it was the policy of only 48% of London maternity units to offer zidovudine to HIV-infected women. During 1995, 44% of HIV-infected women were delivered by elective Cesarean section. Since 1990, 20% of women first diagnosed in pregnancy were reported to have their pregnancy terminated. CONCLUSIONS: Although detection of previously undiagnosed HIV infection in pregnancy remains low in the United Kingdom, and particularly in London, HIV-infected pregnant women who are aware of their status are increasingly active in taking up interventions to reduce transmission to their infants. If all HIV-infected women attending for antenatal care in London consented to testing and took up interventions and termination of pregnancy at the rates observed in this study, the number of vertically infected babies born in London each year could be reduced from an estimated 41 to 13. 相似文献
120.
The protective effect of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), a selenoorganic compound, against hydrogen peroxide (H2O2)-induced cytotoxicity and DNA damage was investigated in a human hepatoma cell line, HepG2. The inhibitory effect of H2O2 on cell growth was determined using the tetrazolium dye colorimetric test (MTT test), and the cytotoxicity and lipid peroxidation were estimated by lactate dehydrogenase (LDH) leakage and malondialdehyde (MDA) formation, respectively. DNA damage was detected using single cell gel electrophoresis (comet assay), and intracellular reactive oxygen species (ROS) formation was measured using a fluorescent probe 2',7'-dichlorofluorescein diacetate (DCFH-DA). The results showed that H2O2 suppressed the growth of HepG2 cells and the addition of ebselen significantly reduced the suppression. Furthermore, ebselen also displayed a dose-dependent reduction of LDH leakage and MDA formation in H2O2-treated cells. The results also demonstrate that ebselen was able to reduce the ROS formation and DNA damaging effect caused by H2O2 in a dose-dependent manner. These findings suggest that ebselen has a strong protective ability against the cytotoxicity and DNA damaging effect caused by reactive oxygen species. 相似文献