首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   724篇
  免费   75篇
  国内免费   1篇
儿科学   32篇
妇产科学   11篇
基础医学   61篇
口腔科学   14篇
临床医学   81篇
内科学   252篇
皮肤病学   14篇
神经病学   19篇
特种医学   131篇
外科学   22篇
综合类   28篇
预防医学   47篇
眼科学   10篇
药学   57篇
肿瘤学   21篇
  2022年   5篇
  2021年   8篇
  2019年   4篇
  2018年   10篇
  2016年   6篇
  2015年   14篇
  2014年   9篇
  2013年   27篇
  2012年   6篇
  2011年   9篇
  2010年   24篇
  2009年   33篇
  2008年   10篇
  2007年   9篇
  2006年   15篇
  2005年   20篇
  2004年   23篇
  2003年   16篇
  2002年   15篇
  2001年   14篇
  2000年   15篇
  1999年   24篇
  1998年   32篇
  1997年   32篇
  1996年   34篇
  1995年   27篇
  1994年   27篇
  1993年   23篇
  1992年   19篇
  1991年   19篇
  1990年   20篇
  1989年   26篇
  1988年   20篇
  1987年   17篇
  1986年   17篇
  1985年   15篇
  1984年   13篇
  1983年   8篇
  1982年   13篇
  1981年   13篇
  1980年   11篇
  1979年   10篇
  1978年   10篇
  1977年   19篇
  1976年   15篇
  1975年   15篇
  1974年   6篇
  1973年   3篇
  1970年   5篇
  1969年   4篇
排序方式: 共有800条查询结果,搜索用时 15 毫秒
71.
Results of the pilot study for the Hypertension in the Very Elderly Trial   总被引:14,自引:0,他引:14  
BACKGROUND: The risks and benefits of treating hypertension in individuals older than 80 years are uncertain. A meta-analysis has suggested that a reduction in stroke events of 36% may have to be balanced against a 14% increase in total mortality. OBJECTIVES: To report the results of the pilot study of the Hypertension in the Very Elderly Trial (HYVET), which is in progress to address these issues. METHODS: The HYVET-Pilot was a multicentre international open pilot trial. In 10 European countries, 1283 patients older than 80 years and with a sustained blood pressure of 160-219/90-109 mmHg were allocated randomly to one of three treatments: a diuretic-based regimen (usually bendroflumethiazide; n = 426), an angiotensin-converting enzyme inhibitor regimen (usually lisinopril; n = 431) or no treatment (n = 426). The procedure permitted doses of the drug to be titrated and diltiazem slow-release to be added to active treatment. Target blood pressure was < 150/80 mmHg and mean follow-up was 13 months. RESULTS: In the combined actively treated groups, the reduction in stroke events relative hazard rate (RHR) was 0.47 [95% confidence interval (CI) 0.24 to 0.93] and the reduction in stroke mortality RHR was 0.57 (95% CI 0.25 to 1.32). However, the estimate of total mortality supported the possibility of excess deaths with active treatment (RHR 1.23, 95% CI 0.75 to 2.01). CONCLUSIONS: The preliminary results support the need for the continuing main HYVET trial. It is possible that treatment of 1000 patients for 1 year may reduce stroke events by 19 (nine non-fatal), but may be associated with 20 extra non-stroke deaths.  相似文献   
72.
Understanding diet and energy balance as risk factors for breast, colon, and other cancers requires information on the contribution of each factor and of interactions among factors to cancer risk. Rodent models for breast cancer provide extensive data on effects of dietary fat and calories, energy balance, body weight gain, and physical activity on tumor development. Analyses of the combined data from many studies have shown clearly that quality and quantity of dietary fat and energy balance contribute independently to increased mammary gland tumorigenesis. These findings were seen in female rats fed diets high in fat (35-40% of calories) compared to rats fed control diets, with approximately 10% of calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46, 215-223). The methods used permit comparison of experimental and epidemiological data, and they may be useful in extrapolating between species and developing public health recommendations. In addition to the contributions of lifetime-diet composition, intake, energy balance, and physical activity to cancer risk, there are questions about the timing and duration of alterations in these factors and about the "dose-response" characteristics of cancer risk to the factors. Endocrine mechanisms may be significant in mammary gland tumor risk, but experimental and epidemiological data indicate that cancers at other sites, such as colon and liver, also are influenced by the factors listed. Other diet and lifestyle factors that influence energy, or specifically fat, metabolism may also affect risk for cancers that are promoted by increased intake of fat and calories. Studies of separate and interactive effects of dietary fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using adjustment of carcinogenesis endpoints for body weight, tumor burden, and latency, they were found to be related to weight gain within treatment groups in 2 of 3 experiments.   相似文献   
73.
Successful pregnancy in a transfusion-dependent thalassaemic patient receiving subcutaneous desferrixaomine is reported. This is the first such case to be described.  相似文献   
74.
Three sibs all presented in the early neonatal period with a salt-losing syndrome. The salt-losing form of congenital adrenal hyperplasia was diagnosed and appropriate treatment with glucocorticosteroids, mineralocorticosteroids, and additional dietary salt started. Although early life was maintained with difficulty, with age all 3 children required decreasing amounts of replacement steroids to maintain normal plasma electrolyte balance. They were reinvestigated at the ages of 15 years and 8 years (twins), when cortisol synthesis and metabolism proved normal, but aldosterone synthesis was blocked by deficiency of 18-dehydrogenase. Rational treatment of these cases of a salt-losing syndrome in which aldosterone synthesis alone is blocked due to lack of the enzyme 18-dehydrogenase requires the administration of a mineralocorticosteroid drug only. Since deoxycorticosterone (acetate or pivalate) requires intramuscular administration, as life-long therapy oral fludrocortisone is preferable. Although fludrocortisone has glucocorticoid activity, the "hydrocortisone equivalent" effect of the small dosage used was unlikely to inhibit either pituitary corticotrophin or growth hormone production.  相似文献   
75.
76.
Blood lead concentration was measured in 398 male and 133 female London civil servants not subject to industrial exposure to heavy metals. The relation between blood lead and serum creatinine concentrations and blood pressure were examined. Blood lead concentration ranged from 0.20 to 1.70 mumol/l with a geometric mean concentrations of 0.58 mumol/l in men and 0.46 mumol/l in women (p less than 0.001). In women blood lead concentration increased with age (r = +0.27; p = 0.002). In the two sexes blood lead concentration was positively correlated with the number of cigarettes smoked a day (men r = +0.17 and women r = +0.22; p less than or equal to 0.01), with the reported number of alcoholic beverages consumed a day (men r = +0.34 and women r = 0.23; p less than 0.01), and with serum gamma-glutamyltranspeptidase (men r = +0.23 and women r = +0.14; for men p less than 0.01). Blood lead concentration was not correlated with body weight, body mass index, and employment grade. In men 14% of the variance of blood lead concentration was explained by the significant and independent contributions of smoking and alcohol intake and in women 16% by age, smoking, and alcohol consumption. In men serum creatinine concentration tended to rise by 0.6 mumol/l (95% confidence interval from -0.2 to +1.36 mumol/l) for each 25% increment in blood lead concentration. In men and women the correlations between blood lead concentration and systolic and diastolic blood did not approach statistical significance. In conclusion, in subjects not exposed to heavy metals at work gender, age, smoking, and alcohol intake are determinants of blood lead concentration. At a low level of exposure, lead accumulation may slightly impair renal function, whereas blood pressure does not seem to be importantly influenced. Alternatively, a slight impairment of renal function may give rise to an increase in blood lead concentration.  相似文献   
77.
Five hundred and seven elderly hypertensive patients were followed for 1 year, 371 for 2 years and 270 for 3 years in a double-blind, randomized, controlled trial in which they received either placebo or 25-50 mg hydrochlorothiazide and 50-100 mg of triamterene daily. One third of the active treatment group also received 250 mg to 2 g methyldopa daily. After 1 year the active treatment group had an average increase in fasting blood sugar of 2.5 mg/dl compared with an average fall of 1.4 mg/dl in the placebo group (P = 0.01). The increase in blood sugar 1 hour and 2 hours after 50 g oral glucose tended to be greater in the actively treated group but these increases did not achieve statistical significance. The effects of diuretic treatment were established after one year and did not increase further over the next 2 years. Overall there was an increase in fasting blood sugar of 5 mg/dl in the active treatment group which occurred mainly in the first year. The hyperglycaemic effect of diuretics appeared to be partly or wholly related to potassium loss since, in both groups, impairment of glucose tolerance was most marked in those in whom serum potassium decreased. The measures of blood sugar were also positively related to systolic pressure before and after treatment.  相似文献   
78.
The QL of patients on long-term pharmacologic treatment needs to be evaluated, especially in the elderly. This article discusses how this should be done and gives the results of studies on three groups of drugs commonly taken by elderly patients. Diuretic treatment does not appear to grossly impair QL, transdermal nitrates for angina do impair QL if used continuously, and tolerance limits their efficacy. Antihypertensive drugs appear to vary widely in their effects on QL. Drugs such as ACE inhibitors, verapamil, and atenolol appear preferable to the older drugs such as methyldopa and the beta-blocker propranolol, which have a central action.  相似文献   
79.
Twenty-six patients (4 months to 6 years old) with achondroplasia complicated by sleep apnea and/or other neurologic manifestations underwent plain computed tomography (CT) of the craniocervical junction; six also underwent CT myelography. For objectification, multiplanar reconstruction was used to complement axial plane measurements by providing coronal and sagittal measurements; multiplanar reconstruction also improved perception of the longitudinal relationships between the brain stem and subarachnoid space. A narrow subarachnoid space was found in all 26 patients; marked cord compression was present in nine, six of whom underwent CT myelography. These six had marked focal obliteration of the subarachnoid space on both plain CT and CT myelography. Since the subarachnoid space immediately above and below the craniocervical junction is normally capacious, when marked constriction was present, no additional information could have been gained from CT myelography. Thus, plain CT was shown to be sufficient for surgical planning (suboccipital decompression) in nine patients with cord compression due to achondroplasia.  相似文献   
80.
Levine  MS; Gasparaitis  AE 《Radiology》1986,160(1):264-265
Severe glucagon-resistant spasm on double-contrast barium enema (DCE) examinations may occasionally lead to a nondiagnostic examination or erroneously suggest colonic disease. In such cases, this glucagon-resistant spasm may be overcome by refilling the colon with single-contrast barium immediately after completion of the DCE examination.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号