全文获取类型
收费全文 | 8381篇 |
免费 | 1369篇 |
国内免费 | 305篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 53篇 |
妇产科学 | 207篇 |
基础医学 | 683篇 |
口腔科学 | 245篇 |
临床医学 | 830篇 |
内科学 | 1103篇 |
皮肤病学 | 24篇 |
神经病学 | 99篇 |
特种医学 | 263篇 |
外科学 | 2628篇 |
综合类 | 1409篇 |
现状与发展 | 2篇 |
预防医学 | 565篇 |
眼科学 | 11篇 |
药学 | 884篇 |
4篇 | |
中国医学 | 852篇 |
肿瘤学 | 185篇 |
出版年
2025年 | 19篇 |
2024年 | 150篇 |
2023年 | 366篇 |
2022年 | 525篇 |
2021年 | 541篇 |
2020年 | 530篇 |
2019年 | 459篇 |
2018年 | 312篇 |
2017年 | 287篇 |
2016年 | 297篇 |
2015年 | 264篇 |
2014年 | 537篇 |
2013年 | 744篇 |
2012年 | 430篇 |
2011年 | 485篇 |
2010年 | 403篇 |
2009年 | 359篇 |
2008年 | 420篇 |
2007年 | 383篇 |
2006年 | 355篇 |
2005年 | 301篇 |
2004年 | 313篇 |
2003年 | 283篇 |
2002年 | 237篇 |
2001年 | 264篇 |
2000年 | 145篇 |
1999年 | 130篇 |
1998年 | 96篇 |
1997年 | 89篇 |
1996年 | 56篇 |
1995年 | 43篇 |
1994年 | 31篇 |
1993年 | 26篇 |
1992年 | 32篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 17篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
ALBERTO Q FARIAS LUCIANA L GONÇALVES EDUARDO LR CANÇADO ANTONIO C SEGURO SILVIA B CAMPOS CLARICE P ABRANTES-LEMOS FLAIR J CARRILHO 《Journal of gastroenterology and hepatology》2006,20(1):147-152
Background and Aims: Primary biliary cirrhosis (PBC) might be complicated by osteoporosis, whose etiology remains unknown but seems to be multifactorial. Prevalence rates of 30% to 60% for distal renal tubular acidosis (DRTA) have been reported in PBC patients, generally as incomplete DRTA. Although it is undisputed that a reduced bone mineral density (BMD) is the expected outcome among patients who have been suffering from longstanding chronic metabolic acidosis, it is unclear if incomplete DRTA is also associated with metabolic bone disease in PBC patients. The present study was undertaken to compare the BMD of PBC patients with and without DRTA.
Methods: The BMD of 23 PBC patients (11 with DRTA and 12 without), all with normal clearance of creatinine, was assessed by dual energy radiograph absorptiometry. The diagnosis of DRTA was made if the urine pH was above 5.4 in all samples after the oral acid overload, showing tubular inability to acidify urine in the presence of test-induced systemic metabolic acidosis.
Results: Densitometric signs of osteoporosis were found in 82% of DRTA cases and in 83% of patients without DRTA (difference not significant). There were no significant differences in BMD measurement, T and Z scores of patients with and without DRTA.
Conclusions: The present study could not support a correlation between the presence of DRTA and the bone loss observed in PBC patients. 相似文献
Methods: The BMD of 23 PBC patients (11 with DRTA and 12 without), all with normal clearance of creatinine, was assessed by dual energy radiograph absorptiometry. The diagnosis of DRTA was made if the urine pH was above 5.4 in all samples after the oral acid overload, showing tubular inability to acidify urine in the presence of test-induced systemic metabolic acidosis.
Results: Densitometric signs of osteoporosis were found in 82% of DRTA cases and in 83% of patients without DRTA (difference not significant). There were no significant differences in BMD measurement, T and Z scores of patients with and without DRTA.
Conclusions: The present study could not support a correlation between the presence of DRTA and the bone loss observed in PBC patients. 相似文献
2.
Michael Nelson† Gillian F. Hague† Cyrus Cooper‡ Valda W. Bunker§ 《Journal of human nutrition and dietetics》1988,1(2):115-127
Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly. 相似文献
3.
Dmitriy A. Yablonskiy William R. Reinus Helmut Stark E. Mark Haacke 《Magnetic resonance in medicine》1997,37(2):214-221
In this paper, the authors quantitate the anisotropy of susceptibility effects in an uniaxial trabecular bone model and show its relevance to clinical MR bone mineral density measurements. A physical model is described that quantitates the anisotropic MR behavior of uniaxial trabecular bone. To test the model, a phantom of parallel polyethylene filaments was scanned every 15° between 0° and 90° with respect to the system's main magnetic field (B0). The distal radial metaphysis of a healthy female volunteer was scanned in orthogonal projections. The signal from each phantom image and each radial image was separated in a pixel-wise fashion into R2 and R2′ maps. As predicted, R2′ relaxation showed anisotropic behavior and changed according to sin2 (?), confirming that columnar structures parallel with B0 will cause no MR susceptibility effects. Scans of the distal radius showed that R2′ relaxation was twice as great with the forearm perpendicular to B0 as when it was parallel to it, demonstrating different contributions from struts and columns. For both phantom and radial bone scans, R2 relaxation was isotropic and did not change with object orientation. 相似文献
4.
VILHJALMUR FINSEN 《Journal of internal medicine》1988,223(5):443-449
Questionnaire responses from 120 men and 337 women over the age of 50 years were studied to determine the prevalence of back pain among the elderly. In order to gain a rough indication of the back pain among elderly women which might be due to osteoporosis, the prevalence was compared in the two sexes. The prevalence of back pain without radiation to the legs and concomitant morbidity was found to be similar among men and women up to the 70–79-year age-group. After this age the prevalence was higher in women. Those with exceptional loss of body height or kyphosis had a high prevalence of back pain, while those who had sustained previous hip or radius fractures did not. There was increasing prevalence of back pain among women with increasing number of previous fractures. The study gives little indication of serious morbidity of osteoporosis in the form of back pain before very old age. 相似文献
5.
Cyclic hormonal replacement therapy after the menopause: Transdermal versus oral treatment 总被引:2,自引:0,他引:2
M. Cortellaro T. Nencioni C. Boschetti S. Ortolani F. Buzzi B. Francucci M. P. Caraceni P. Abelli F. Polvani C. Zanussi 《European journal of clinical pharmacology》1991,41(6):555-559
Summary In an open, randomized, comparative, between-patient trial, 45 postmenopausal women were treated for 4 months with cyclical transdermal oestradiol 0.05 mg per day or oral conjugated equine oestrogens 0.625 mg per day, in both cases, plus, medroxyprogesterone acetate 10 mg per day on the last 8 days of each cycle. Similar relief from postmenopausal symptoms was obtained with both treatments. Post-treatment histological evaluation of the endometrium did not reveal neoplastic or hyperplastic change in any patient.Early follicular-phase plasma oestradiol levels were observed only after transdermal oestradiol. There was a significant reduction in serum total cholesterol and LDL cholesterol in both treatment groups, with no difference between treatments, whereas serum triglyceride levels were decreased only by transdermal oestradiol. Plasma calcium and phosphorus fell significantly and serum intact parathyroid hormone rose significantly, with no difference between the therapies. No significant changes were observed in clotting factors.Transdermal oestradiol appears to be an effective and safe hormonal replacement therapy, and this route of administration may be responsible for the more useful action of the drug on serum lipids and plasma oestradiol levels. 相似文献
6.
Boonen S, Broos P, Dequeker J, Bouillon R (Department of Internal Medicine, Division of Geriatric Medicine, the Arthritis and Metabolic Bone Disease Research Unit, the Department of Traumatology and Emergency Surgery and the Laboratory for Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium). The prevention or treatment of age-related osteoporosis in the elderly by systemic recombinant growth factor therapy (rhIGF-I or rhTGFβ): a perspective (Review). J Intern Med 1997; 242 : 285–90.
Both insulin-like growth factor-I (IGF-I) and transforming growth factor β (TGFβ) have powerful modulatory effects in a variety of tissues. A major target of action is the skeletal system, where they enhance bone formation and decrease matrix degradation, thus playing a part in the maintenance of bone mass. Because of the potent mitogenic effect of these agents on osteoblasts, recombinant IGF-I (rhIGF-I) and recombinant TGFβ (rhTGFβ) have potential as drugs to stimulate bone formation in the prevention and treatment of osteoporosis. Using biochemical markers, subcutaneous rhIGF-I therapy has been shown to increase bone turnover and bone formation in nonosteoporotic older people. However, a corresponding increase in bone mass has not yet been documented nor have there been reports yet on the effects of systemically administered rhTGFβ in humans. Further investigation is required to define the clinical potential of rhIGF-I and rhTGFβ as therapeutic agents in age-related osteoporosis. 相似文献
Both insulin-like growth factor-I (IGF-I) and transforming growth factor β (TGFβ) have powerful modulatory effects in a variety of tissues. A major target of action is the skeletal system, where they enhance bone formation and decrease matrix degradation, thus playing a part in the maintenance of bone mass. Because of the potent mitogenic effect of these agents on osteoblasts, recombinant IGF-I (rhIGF-I) and recombinant TGFβ (rhTGFβ) have potential as drugs to stimulate bone formation in the prevention and treatment of osteoporosis. Using biochemical markers, subcutaneous rhIGF-I therapy has been shown to increase bone turnover and bone formation in nonosteoporotic older people. However, a corresponding increase in bone mass has not yet been documented nor have there been reports yet on the effects of systemically administered rhTGFβ in humans. Further investigation is required to define the clinical potential of rhIGF-I and rhTGFβ as therapeutic agents in age-related osteoporosis. 相似文献
7.
B Schwahn E Mokov K Scheidhauer B Lettgen E Schönau 《Acta paediatrica (Oslo, Norway : 1992)》1998,87(1):61-63
The bone mineral density (BMD) of 14 children, adolescents, and adults with phenylketonuria (PKU) on dietary treatment (age 5-28 y; 6F, 8M) was investigated using peripheral quantitative computed tomography (pQCT) of the distal radius. BMD of total (TBMD) and spongy bone (SBMD) were compared to those of healthy gender-, age-, weight- and height-matched controls. We found a significant decrease of SBMD in patients with PKU while TBMD was only slightly decreased, reaching no statistical significance. These results indicate minor changes of BMD in patients with PKU under treatment, which are more accentuated in the trabecular bone compartment. One additional patient who was untreated until the pQCT investigation at the age of 10 y also showed markedly decreased SBMD and TBMD. 相似文献
8.
目的 探讨低剂量结合型雌激素(CE)和安宫黄体酮(MPA)联合应用对骨代谢的影响,方法34例绝经后妇女随机分为两组,试验组17例,CE0.625mg与MPA2mg隔日口服交替应用,对照组17例,口服CD0.625mg/d,每月连续服用25d,后10d加用MPA4mg。两组均连续服用4周期,于用药前后分别测定血碱性磷酸酶(ALP)及尿Ca/Cr比值。结果 实验组完成治疗者16例,对照组完成治疗者15 相似文献
9.
10.
Obesity and subcutaneous fat patterning in relation to survival of postmenopausal breast cancer patients participating in the DOM-project 总被引:2,自引:0,他引:2
Isolde den Tonkelaar Frits de Waard Jacob C. Seidell Jacques Fracheboud 《Breast cancer research and treatment》1995,34(2):129-137
Summary The effect of obesity and fat distribution on survival of breast cancer patients was studied prospectively in 241 women with a natural menopause who participated in a breast cancer screening project, the DOM-project in Utrecht, The Netherlands. Mean follow-up time was 9.1 years and endpoint of interest was death from breast cancer. Fat distribution was assessed by contrasting groups of subscapular and triceps skinfold thickness.No significant differences in survival time between more obese (Quetelet's index 26 kg/m2) and leaner (Quetelet's index < 26 kg/m2) patients or between patients with central fat distribution and patients with peripheral fat distribution were observed. Analyses were stratified by axillary node status, estrogen receptor status, and way of detection (by first screening or afterwards). Results of the stratified analyses were suggestive of a modifying effect of these factors.The absence of an association between obesity and survival time might be explained by two counteracting mechanisms. On the one hand obesity might be related to impaired survival, due to a tumor growth promoting effect of extra-ovarian estrogens. On the other hand obesity might be related to improved survival in a screened population, because obese patients profit more from screening by earlier detection of tumors than leaner counterparts. 相似文献