全文获取类型
收费全文 | 876篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 9篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
轻工业 | 4篇 |
石油天然气 | 2篇 |
无线电 | 2篇 |
一般工业技术 | 6篇 |
冶金工业 | 845篇 |
原子能技术 | 1篇 |
自动化技术 | 5篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 2篇 |
1999年 | 23篇 |
1998年 | 238篇 |
1997年 | 149篇 |
1996年 | 102篇 |
1995年 | 47篇 |
1994年 | 34篇 |
1993年 | 45篇 |
1992年 | 4篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1983年 | 2篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 27篇 |
1976年 | 91篇 |
1974年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有878条查询结果,搜索用时 343 毫秒
101.
AM Sartori MH Lopes LA Benvenuti B Caramelli A di Pietro EV Nunes LP Ramirez MA Shikanai-Yasuda 《Canadian Metallurgical Quarterly》1998,59(5):784-786
We report a human immunodeficiency virus (HIV)-infected man with chronic Chagas' disease who developed a congestive heart failure that could not be clinically controlled. Endomyocardial biopsy revealed severe myocarditis and the xenodiagnosis result was positive, but Trypanosoma cruzi by direct microscopic examination of the blood was found only four months after the symptoms had started. Treatment with benznidazole was effective in reducing parasitemia, stabilizing the clinical status, and controlling tissue damage related to the parasite. Although the finding of T. cruzi trypomastigotes by direct microscopic examination of the blood has been considered the mark of Chagas' reactivation in immunocompromised patients with chronic disease, in this case it was a late finding. 相似文献
102.
The material comprises 77 patients with suspected appendicitis seen in a district community hospital. In the presence of a surgeon with laparoscopic experience laparoscopy was performed in 23 patients. In two patients the laparoscopy was only diagnostic, and in two patients adhesions or friable gangrenous appendicitis necessitated conversion to conventional appendicectomy. Nineteen patients thus had a laparoscopic appendicectomy performed with a median operation time of 63 minutes and a median hospital stay of two days. One patient with gangrenous appendicitis and a periappendicular abscess was readmitted after three weeks because of deep infection, which resolved after antibiotic treatment. The remaining 54 patients had a conventional appendicectomy performed, with a median operation time of 40 minutes and a median hospital stay of three days. There were six complications in this group. We conclude that laparoscopic appendicectomy is a safe alternative to open operation with benefits for the patient in form of lesser pain, shorter hospital stay, fewer complications, better cosmetic outcome, and shorter time to normal activity. 相似文献
103.
To evaluate the effects of contractions on the kinetics of uptake and oxidation of palmitate in a physiological muscle preparation, rat hindquarters were perfused with glucose (6 mmol/l), albumin-bound [1-14C]palmitate, and varying amounts of albumin-bound palmitate (200-2,200 micro mol/l) at rest and during muscle contractions. When plotted against the unbound palmitate concentration, palmitate uptake and oxidation displayed simple Michaelis-Menten kinetics with estimated maximal velocity (Vmax) and Michaelis-Menten constant (Km) values of 42.8 +/- 3.8 (SE) nmol . min-1 . g-1 and 13.4 +/- 3.4 nmol/l for palmitate uptake and 3.8 +/- 0.4 nmol . min-1 . g-1 and 8.1 +/- 2.9 nmol/l for palmitate oxidation, respectively, at rest. Whereas muscle contractions increased the Vmax for both palmitate uptake and oxidation to 91.6 +/- 10.1 and 16.5 +/- 2.3 nmol . min-1 . g-1, respectively, the Km remained unchanged. Vmax and Km estimates obtained from Hanes-Woolf plots (substrate concentration/velocity vs. substrate concentration) were not significantly different. In the resting perfused hindquarter, an increase in palmitate delivery from 31.9 +/- 0.9 to 48.7 +/- 1.2 micro mol . g-1 . h-1 by increasing perfusate flow was associated with a decrease in the fractional uptake of palmitate so that the rates of uptake and oxidation of palmitate remained unchanged. It is concluded that the rates of uptake and oxidation of long-chain fatty acids (LCFA) saturate with an increase in the concentration of unbound LCFA in perfused skeletal muscle and that muscle contractions, but not an increase in plasma flow, increase the Vmax for LCFA uptake and oxidation. The data are consistent with the notion that uptake of LCFA in muscle may be mediated in part by a transport system. 相似文献
104.
MI Matee EF Lyamuya EE Simon JH Mwinula EC Mbena LP Samaranayake FF Scheutz 《Canadian Metallurgical Quarterly》1995,72(11):694-698
Seroprevalence of HIV-1 infection was determined in children aged between eighteen months and five years, attending maternal and child health (MCH) clinics in Dar es Salaam, Tanzania. A total of 889 children were eligible for the study, however seven children could not be enrolled because their mothers/guardians absconded and blood could not be drawn from 21 children due to refusal of mothers/guardians and from another 12 children due to technical reasons. Therefore, the participation rate was 95.5%. Of the 849 children screened, 14 (1.65%) were found to have IgG anti HIV-1 antibodies in their sera. The main clinical features found in children with symptomatic HIV-1 disease were weight loss, generalized lymphadenopathy, recurrent fevers, and prolonged diarrhoea. The utility of clinical features suggestive of HIV-1 infection (according to CDC classification) in identifying HIV-1 infection in children was evaluated and found to have high sensitivity (100%), specificity (96.9%) and negative predictive value (100%), but a low positive predictive value (35%). Marked variations in progression to symptomatic phase were noted, whereby some relatively young children had progressed to symptomatic phase (CDC class P-2A), while some older children were still in the asymptomatic stage (CDC class P-1 C). None of the symptomatic HIV-1 infected children presented with neurological disease, severe opportunistic infections, or malignancies. Although reduced mid-upper arm circumference and weight-for-age were associated with HIV seropositivity, these clinical parameters had low positive predictive values compared to the CDC classification. 相似文献
105.
JH Krystal LP Karper A Bennett DC D'Souza A Abi-Dargham K Morrissey D Abi-Saab JD Bremner MB Bowers RF Suckow P Stetson GR Heninger DS Charney 《Canadian Metallurgical Quarterly》1998,135(3):213-229
Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist with psychotogenic and dissociative effects in healthy humans. These cognitive and perceptual effects in humans are reportedly reduced by benzodiazepine premedication. This study assessed the interactive effects of a ketamine (i.v. bolus of 0.26 mg/kg followed by an infusion of 0.65 mg/kg per hour) and lorazepam 2 mg., PO, in humans. Twenty-three healthy subjects completed 4 test days involving the oral administration of lorazepam or matched placebo 2 h prior to the i.v. infusion of ketamine or placebo. Ketamine: 1) produced behaviors similar to the positive and negative symptoms of schizophrenia as assessed by the Brief Psychiatric Rating Scale (BPRS); 2) evoked perceptual alterations as measured by the Clinician-Administered Dissociative States Scale (CADSS); 3) impaired performance on the Wisconsin Card Sorting Test (WCST) and other tests sensitive to frontal cortical impairment; and 4) had amnestic effects. Lorazepam produced attention impairments, concrete proverb interpretations, and recall impairments. Lorazepam reduced ketamine-associated emotional distress and there was a non-significant trend for it to decrease perceptual alterations produced by ketamine. However, it failed to reduce many cognitive and behavioral effects of ketamine, including psychosis. Further, lorazepam exacerbated the sedative, attention-impairing, and amnestic effects of ketamine. There was no evidence of pharmacokinetic interaction between these medications. These data suggest that subhypnotic lorazepam and ketamine show a spectrum of interactive effects, ranging from antagonism to potentiation. 相似文献
106.
E Souied B Segues I Ghazi JM Rozet S Chatelin S Gerber I Perrault A Michel-Awad ML Briard G Plessis JL Dufier A Munnich J Kaplan 《Canadian Metallurgical Quarterly》1997,34(10):793-797
The aim of this study was to assess the effect of menopause on circadian profile of blood pressure (BP) and heart rate (HR) in the normotensive pre- and postmenopausal women. Systolic BP (SBP), diagnostic BP (DBP) and HR were monitored every 30 min for 48 hrs using noninvasive ambulatory BP monitoring in 24 premenopausal and 40 postmenopausal women. Mean 48-hours, daytime (awake), and nighttime (sleeping) SBP, DBP and HR values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP, DBP and HR were calculated according to the following formula. NRR (%9 = [(daytime mean-nighttime mean)/daytime mean] x 100. The study subjects were then divided into two groups according to the presence (dipper) or absence (nondipper) of a significant reduction in nocturnal BP (> 10%). Mean SBP, DBP and HR measured over 48 hours were similar between the premenopausal and the postmenopausal group. The NRR of DBP and HR in the postmenopausal group were significantly smaller than those in the premenopausal group (17.1 +/- 6.0% vs. 13.5 +/- 7.0%, 241.1 +/- 6.0% vs. 19.8 +/- 9.0%: p < 0.05). There tended to be higher prevalence of nondipper in the postmenopausal (37%) than in the premenopausal group (29%). 相似文献
107.
108.
SJ Mubarak AR Hargens CA Owen LP Garetto WH Akeson 《Canadian Metallurgical Quarterly》1976,58(7):1016-1020
The wick catheter technique was developed in 1968 for measurement of subcutaneous pressure and has been modified for easy intramuscular insertion and continuous recording of interstitial fluid pressure in animals and humans. Studies in dogs of the anterolateral compartment of the leg in simulation of the compartment syndrome showed the technique to be accurate and reproducible. The wick catheter technique is capable of important clinical applications in the diagnosis and treatment of acute and chronic compartment syndromes. 相似文献
109.
110.