全文获取类型
收费全文 | 1056篇 |
免费 | 3篇 |
专业分类
化学工业 | 33篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
轻工业 | 17篇 |
水利工程 | 2篇 |
一般工业技术 | 11篇 |
冶金工业 | 988篇 |
原子能技术 | 2篇 |
自动化技术 | 3篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 29篇 |
1998年 | 270篇 |
1997年 | 161篇 |
1996年 | 114篇 |
1995年 | 55篇 |
1994年 | 66篇 |
1993年 | 54篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 33篇 |
1976年 | 75篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1059条查询结果,搜索用时 17 毫秒
41.
J Zhang P Alfonso NR Thotakura J Su M Buergin D Parmelee AW Collins M Oelkuct S Gaffney S Gentz DP Radman GF Wagner R Gentz 《Canadian Metallurgical Quarterly》1998,12(3):390-398
Pustulosis palmoplantaris (PPP) is a common chronic skin disease, which is very resistant to treatment. It is not known why the lesions are located in the palms and soles. There are few studies of the disease and in particular studies of the histology. Fifty-nine patients with PPP answered a questionnaire concerning their medical history and 39 of them were clinically examined. Biopsy specimens were taken from involved skin in 22 of the 39 patients and studied immunohistologically for tryptase+ mast cells, EG2+ eosinophils, lipocalin+ neutrophils and CD3+ T lymphocytes. The sweat gland and sweat duct were visualized with AE1/AE3 antibody (cytokeratins 1-8, 10, 14/15, 16, 19). In addition to neutrophils in the pustule and lymphocytes in the upper dermis, there were also large numbers of mast cells and eosinophils in the subpustular area. Numerous eosinophils were present in the pustule. The epidermal part of the eccrine duct was not detectable in any of the specimens from patients with PPP but was present in all of the nine control persons (including two smokers). The results indicate that the acrosyringium is involved in the inflammation and also that mast cells and eosinophils participate in a hitherto unknown way. Of the 39 patients clinically examined, two had previously diagnosed thyroid disease and two had gluten hypersensitivity. Seventeen had one or several abnormal serum concentrations of thyroid-stimulating hormone, thyroxin, antibodies against thyroglobulin or thyroperoxidase and 10 had immunoglobulin (Ig) A antibodies to gliadin. The mean +/- SD for serum IgA and for eosinophil cationic protein was increased. From the questionnaire the most notable finding was that 56 of the 59 patients had been or still were smokers, all of whom had started smoking before the first signs of PPP. We hypothesize that the acrosyringium might be the target for the inflammation and that PPP is linked to autoimmune thyroid disease and smoking. 相似文献
42.
A previous study reported that intercellular adhesion molecule-1 (ICAM-1) expression by human vascular endothelial cells (HUVEC) is augmented by intracellular signal transmission mainly through the protein kinase C (PKC) system stimulated by TXA2 receptors. In the present study, we show that a TXA2 receptor agonist, U46619, augments the expression of not only ICAM-1, but also vascular cell adhesion molecule-1 (VCAM-1) or endothelial leucocyte adhesion molecule-1 (ELAM-1) in HUVEC both at protein and mRNA levels. Pretreatment with SQ29,548 (a TXA2 receptor antagonist) or PKC inhibitors greatly diminished the extent of U46619-induced mRNA accumulation and surface expression of the adhesion molecules. An inhibitor of nuclear factor kappaB (NF-kappaB) activation, PDTC, diminishes U46619-induced VCAM-1 mRNA accumulation. NAC, which inhibits NF-kappaB and activation protein 1 (AP-1) binding activity, inhibits the expression of ICAM-1 or ELAM-1 at protein and mRNA levels. These findings suggest that ICAM-1 or ELAM-1 expression of HUVEC stimulated via TXA2 receptors is augmented by induction of NF-kappaB and AP-1 binding activity through the PKC system, and that VCAM-1 expression is augmented by induction of NF-kappaB binding activity. 相似文献
43.
G Addolorato E Capristo AV Greco GF Stefanini G Gasbarrini 《Canadian Metallurgical Quarterly》1998,244(5):387-395
OBJECTIVES: To evaluate the influence of chronic alcohol abuse on body composition and energy metabolism in patients affected by chronic alcoholism (group A) compared with a group of healthy social drinkers (group B). SETTING: A university hospital clinic in Italy. SUBJECTS: A total of 32 alcoholics without clinical or laboratory signs of liver cirrhosis and malabsorption. MEASUREMENTS: Body composition was assessed by anthropometric measurements. Resting energy expenditure (REE) and substrate oxidation rate was measured by indirect calorimetry. Daily caloric intake was computed on the basis of a food diary compiled over 7 days. RESULTS: Alcoholics showed a significantly lower body weight (P < 0.05) and a significant lower fat mass (P < 0.05) compared with controls. A higher waist-to-hip ratio was found in group A than in group B, both as a whole group (P < 0.01) or separated by gender (females, P < 0.01) and males, P < 0.001), indicating a prevalence of fat distribution in the abdominal region in alcoholics. REE was significantly higher in group A than in group B (P < 0.05). The non-protein respiratory quotient was significantly lower in group A than in group B (P < 0.001) with a consequent higher utilization of lipids (P < 0.01) and a lower carbohydrate oxidation (P < 0.05) in group A. The energy intake provided only by food ingestion was found to be significantly higher in group B (P < 0.01), whilst the total caloric intake, computed as food intake plus alcohol intake, was higher in group A (P < 0.01). CONCLUSIONS: Alcoholics, as compared with social drinkers, showed a lower body weight due essentially to a fat mass reduction, a higher REE value normalized by fat-free mass, and a preferential utilization of lipids as energy substrate. These findings might suggest that chronic ethanol abuse is able to determine an impairment of nutritional status due, at least in part, to an alteration of the substrate oxidation. 相似文献
44.
NR Powe RI Griffiths AJ Watson GF Anderson G de Lissovoy JW Greer RJ Herbert RA Milam PK Whelton 《Canadian Metallurgical Quarterly》1994,4(7):1455-1465
To examine the effects of recombinant human erythropoietin (rHuEPO) on hospital utilization, hospital costs, and Medicare reimbursements for hospital care, a longitudinal, matched cohort study was conducted using Medicare claims data of 23,806 Medicare-eligible, dialysis patients who received rHuEPO, did not have a transplant, and were alive for 18 mo or longer and 22,720 controls matched on age, sex, race, cause of ESRD, and dialysis modality. The relative odds (rHuEPO versus control) of admission for all causes and for specific causes over 9 mo, adjusted for admission in the prior 9 mo and the per patient change in total admissions, inpatient days, hospital costs, and Medicare hospital payments between the prior 9-mo period and the subsequent 9-mo period was examined. The adjusted relative odds (95% confidence interval) of admission (rHuEPO versus control) was: higher and statistically significant for all causes, 1.08 (1.03 to 1.14); seizure, 1.52 (1.28 to 1.75); vascular access revision, 1.11 (1.06 to 1.17), and heart failure, 1.17 (1.09 to 1.26); higher but not statistically significant for angina, 1.09 (0.99 to 1.20) and stroke, 1.08 (0.86 to 1.31); and lower but not statistically significant for myocardial infarction, 0.91 (0.72 to 1.10); peripheral vascular disease, 0.81 (0.60 to 1.02); anemia, 0.86 (0.56 to 1.17); and depression, 0.89 (0.37 to 1.40). The mean change per 1,000 patients in admissions was less by 38 (P = 0.03) because of fewer readmissions, and in days was 1,309 less (P < 0.001), for patients treated with rHuEPO versus controls. The mean change per patient in hospital costs was $371 less and was statistically significant (P = 0.03) and in Medicare hospital payments was $132 less but was not statistically significant (P = 0.43) for patients treated with rHuEPO versus controls. rHuEPO was associated with an increase in the probability of hospital admission (particularly admissions potentially related to adverse effects) but a decrease in readmissions, overall admissions, hospital days, and cost to hospitals in this cohort of patients surviving for 18 mo. Although not realized short term, Medicare savings from potential rHuEPO-related reductions in hospital care may be long term through future adjustments in diagnosis-related group-based hospital payment. 相似文献
45.
46.
RH Swerdlow JK Parks JN Davis DS Cassarino PA Trimmer LJ Currie J Dougherty WS Bridges JP Bennett GF Wooten WD Parker 《Canadian Metallurgical Quarterly》1998,44(6):873-881
Recent data suggesting complex I dysfunction in Parkinson's disease (PD) arises from mitochondrial DNA (mtDNA) mutation does not conclusively answer whether the responsible genetic lesion is inherited (primary) or somatic (secondary). To address this question, we identified a family in which multiple members over three generations are affected with PD through exclusively maternal lines. Cytoplasmic hybrids (cybrids) were created for 15 family members over two generations by transferring each individual's mtDNA to mtDNA-depleted human neuroblastoma cells. Eight of the 15 cybrid lines contained mtDNA obtained from maternally descended family members and seven contained mtDNA from paternally descended family members. After 6 weeks of culture, cybrid cell lines were assayed for complex I activity and oxidative stress, and mitochondrial morphology was analyzed by electron microscopy. Compared with the cybrid lines containing mtDNA from paternal descendants, cybrid lines containing mtDNA from maternal descendants had lower complex I activity, increased reactive oxygen species production, increased radical scavenging enzyme activities, and more abnormal mitochondrial morphologic features. These findings were present in cybrid lines containing mtDNA from maternal descendants with PD as well as in currently asymptomatic young maternal descendants, and support a precedent for inherited mtDNA mutation in some persons with PD. 相似文献
47.
The effector domain mutants of oncogenic Ras, V12S35 Ras, V12G37 Ras, and V12C40 Ras were tested for their abilities to mediate tumorigenic and metastatic phenotypes in athymic nude mice when expressed in NIH 3T3 fibroblasts. All mutants displayed comparable tumorigenic properties, but only the mutant that activates the Raf-mitogen-activated protein kinase kinase (MEK)-extracellular regulated kinase (ERK) 1/2 pathway, V12S35 Ras, induced tumors in the experimental metastasis assay. Furthermore, direct activation of the MEK-ERK1/2 pathway in NIH 3T3 cells by mos or a constitutively active form of MEK was sufficient to induce metastasis whereas R-Ras, which fails to activate the ERK1/2 pathway, is tumorigenic but nonmetastatic. The subcutaneous tumors and lung metastases derived from V12S35 Ras-transformed NIH 3T3 cells expressed higher levels of activated ERK1/2 in culture when compared with the parental cellular pool before injection, indicating that selection for cells with higher levels of activated ERK1/2 occurred during tumor growth and metastasis. By contrast, cells explanted from V12G37-Ras or V12C40-Ras-induced tumors did not show changes in the level of ERK1/2 activation when compared with the parental cells. When tumor-explanted cell lines derived from each of the effector domain mutants were passaged one additional time in vivo, all mediated rapid tumor growth, but, again, only cells derived from V12S35 Ras-tumors formed numerous metastatic lesions within the lung. These results show that the metastatic properties of the Ras effector domain mutants segregate, and that, whereas Ras-mediated tumorigenicity can arise independently of ERK1/2 activation, experimental metastasis appears to require constitutive activation of the ERK1/2 pathway. 相似文献
48.
49.
Vaginal colonization of mothers with Group B beta-hemolytic streptococcus (GBS) has been recognized as a risk factor for neonatal morbidity. The relationship of GBS colonization to risks for the mother who undergoes cesarean section has not been defined. In this study, we found that, among patients who underwent cesarean section, the 19% of them who were colonized with GBS had a higher incidence of standard fever (66.6% vs. 30.5%), clinical diagnosis of endomyometritis (61.1% vs. 12.5%), and use of antibiotics (61.1% vs. 26.3%) in relationship to a significantly increased frequency of premature rupture of the membranes (50.0% vs. 14.8%). Reasons for the association between vaginal colonization and increased morbidity are discussed. 相似文献
50.
A case of a retained gallstone in the common bile duct after cholecystectomy (in a 38-year old man) is reported in which infusions with saline and spasmolytics failed to flush out the retained stone into the duodenum. An infusion with sodium cholate over nine days through the T-tube was successful in dissolution of the radiolucent stone. 相似文献