全文获取类型
收费全文 | 975篇 |
免费 | 3篇 |
专业分类
化学工业 | 1篇 |
机械仪表 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 3篇 |
冶金工业 | 967篇 |
原子能技术 | 1篇 |
自动化技术 | 2篇 |
出版年
2022年 | 1篇 |
2016年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2011年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 1篇 |
1999年 | 22篇 |
1998年 | 286篇 |
1997年 | 169篇 |
1996年 | 106篇 |
1995年 | 51篇 |
1994年 | 62篇 |
1993年 | 57篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 5篇 |
1977年 | 35篇 |
1976年 | 81篇 |
1975年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有978条查询结果,搜索用时 0 毫秒
971.
972.
973.
The technique of injection and the results of a series of 124 chemical lumbar sympathectomies, performed on 97 patients, are described. Sixty-eight patients, over 60 years of age, had their sympathectomy because of peripheral arteriosclerotic disease. Fifty-two of these patients benefited in terms of pain relief and only one required amputation. Sixteen patients, under 60 years of age, had their sympathectomy because of peripheral arteriosclerotic disease. Ten of these patients benefited but it is recommended that, where possible, other methods of treatment should be used in this younger age group. Thirteen patients, mostly elderly, had their sympathectomy because of diabetic ischaemic disease. Six only of these patients benefited, but it is felt that chemical sympathectomy can be recommended as a way of helping some of these patients who would otherwise have amputation. 相似文献
974.
B Tucker F Fabbian M Giles RC Thuraisingham AE Raine LR Baker 《Canadian Metallurgical Quarterly》1997,12(4):724-728
BACKGROUND: Left ventricular hypertrophy (LVH) is both common and an important predictor of risk of death in end-stage renal failure (ESRF). In mild to moderate chronic renal failure (CRF), the timing of onset of LVH and the factors involved in its initial development have not been fully elucidated. The present study was undertaken to examine the prevalence and potential determinants of echocardiographically determined LVH in this connection, and to compare 24-h ambulatory blood pressure (BP) recordings with BP measured at a previous clinic visit. METHODS: From a cohort of 120 non-diabetic patients who had been attending a nephrology clinic, 118 agreed to participate in the study. Of these we selected for analysis 85 stable patients (37 male). Patients with known cardiovascular disease, those with a history of poor compliance with antihypertensive medication, and those in whom such medication had been changed in the previous 3 months were excluded. Clinic BP, 24-h ambulatory BP, echocardiography, body mass index (BMI), serum creatinine (SCr), creatinine clearance (CrCl), haemoglobin (Hb), fasting cholesterol (CHOL), triglyceride TRIGL), plasma glucose, calcium (Ca), phosphate (PO4), alkaline phosphatase (ALK PHOS), parathyroid hormone (PTH) concentrations, and 24-h urinary protein were assessed in all patients. Seventy-seven per cent were on antihypertensive medication. RESULTS: LVH was detected in 16% of patients with CrCL > 30 ml/min, and 38% of patients with CrCl < 30 ml/min. By stepwise regression analysis, ambulatory systolic BP (P < 0.0001), male gender (P < 0.0001), BMI (P < 0.0002), and Hb concentration (P < 0.002) were the only independent determinants of left ventricular (LV) mass. Nocturnal systolic BP (P < 0.02) was the main determinant of LVH in the group of patients with advanced CRF. The correlation between left ventricular mass index (LVMI) and mean 24-h ambulatory systolic BP (r = 0.52, 95% confidence interval 0.50-0.54) was statistically significantly stronger than with outpatient systolic BP (r = 0.25, 95% confidence interval 0.23-0.27). The same was true for the correlation between LVMI and mean 24-h ambulatory diastolic BP (r = 0.42, 95% confidence interval 0.40-0.44), and outpatient diastolic BP (r = 0.22, 95% confidence interval 0.20-0.24). CONCLUSIONS: Twenty-four hour ambulatory BP recording and echocardiography are required for accurate diagnosis of inadequate BP control and early LVH in patients with chronic renal impairment, independent determinants of which are hypertension, male sex, BMI, and anaemia. 相似文献
975.
A variety of laser systems are under investigation as potential tools in dentistry. Most of these systems have been shown to be efficacious for soft tissue surgery of the mucous membranes; however, cutting bone and dental hard tissues has only recently been possible. In this report from the University of California at Los Angeles School of Dentistry, a review of laser applications in dentistry is discussed. The utility of a new laser system using an erbium YSGG medium with air water spray to cut soft tissues, bone, enamel and dentin is under investigation and preliminary research findings are presented. 相似文献
976.
JE Valenzuela DG Kogut AJ McCullough JR Colón Pagán U Shah J Whipple LR Gilde TJ Simon 《Canadian Metallurgical Quarterly》1996,91(12):2516-2522
OBJECTIVE: The purpose of this multicenter, randomized, double-blind study, conducted in 520 patients, was to compare the efficacy and safety of omeprazole (40 and 20 mg once daily) with placebo in the treatment of benign gastric ulcer. METHODS: Treatment with omeprazole or placebo lasted 4 wk; those whose ulcers remained unhealed continued the same treatment regimen for an additional 4 wk. The effects of therapy were determined by endoscopy and assessment of GI symptoms. Safety and tolerability were evaluated through reported adverse events, physical examinations, and laboratory tests. RESULTS: At weeks 4 and 8, the proportion of patients with healed ulcers was significantly greater in the omeprazole 40- and 20-mg groups than in the placebo group (p < 0.01). At week 8, the healing rate was significantly greater in the 40-mg group than in the 20-mg group (82.7 vs 74.8%, p < 0.05). In patients with large ulcers (>1 cm), the 40-mg regimen was associated with a significantly higher healing rate (78.9%) than both the 20-mg regimen (61.4%) and placebo (34.6%) at week 8 (p < 0.05 vs omeprazole 20 mg; p < 0.01 vs placebo). Healing rates in patients with small ulcers were similar for the 40- and 20-mg groups. Omeprazole was well tolerated, with no significant differences versus placebo in the overall incidence of clinical or laboratory adverse events. CONCLUSIONS: Omeprazole 40 and 20 mg, administered once daily, healed a significantly greater proportion of patients than did placebo. The 40-mg regimen offered significant advantages over the 20-mg regimen in patients with large ulcers. 相似文献
977.
Transient memory impairment in monkeys with bilateral lesions of the entorhinal cortex 总被引:1,自引:0,他引:1
Performance on five behavioral tasks was assessed post-operatively in Macaca fascicularis monkeys prepared with bilateral lesions of the entorhinal cortex (E group). Three of the tasks were also readministered 9-14 months after surgery. Initial learning of the delayed nonmatching-to-sample (DNMS) task was impaired in the E animals relative to unoperated control monkeys. On the delay portion of DNMS, the performance of E animals was nearly at control levels at short delays (up to 60 sec) but was impaired at 10 min and 40 min retention intervals. On the retest of DNMS, the E animals performed normally at all retention intervals. The E animals were unimpaired on the four other memory tasks. Neuroanatomical studies revealed a significant transverse expansion of the terminal field of the perirhinal cortical projection in the CA1 region of the hippocampus. Compared to unlesioned, anatomical control monkeys, the transverse length of the perirhinal terminal field in CA1 increased approximately 70% in the E monkeys. Although this was a striking morphological alteration, it is not known whether the sprouting of this projection influenced the behavioral recovery. The results of these studies suggest that the entorhinal cortex may normally participate in the learning and performance of tasks that are dependent on the medial temporal lobe memory system. However, recovery of normal DNMS performance demonstrates that the entorhinal cortex is not, by itself, essential for learning and performance of such tasks. 相似文献
978.
AIM: To compare the proposed diagnostic criteria of subacute infectious endocarditis (SIE) to criteria developed by von Reyn et al. and by Duke Endocarditis Service. MATERIALS AND METHODS: 69 SIE cases and suspected recurrences have been analysed for patients observed in the Therapeutic Clinic of the Moscow medical University in 1990-1997. RESULTS: According to the authors' criteria accurate and tentative SIE diagnosis were made in 82 and 18% of patients, respectively. The other two diagnostic approaches in this situation increase the percentage of presumptive diagnosis and decrease that of the definite one. CONCLUSION: The criteria proposed by the authors are more sensitive in diagnosis of definite SIE, are less dependent on echocardiography quality and bacteriological diagnosis. 相似文献