全文获取类型
收费全文 | 845篇 |
免费 | 53篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 31篇 |
妇产科学 | 15篇 |
基础医学 | 106篇 |
口腔科学 | 15篇 |
临床医学 | 87篇 |
内科学 | 207篇 |
皮肤病学 | 7篇 |
神经病学 | 44篇 |
特种医学 | 83篇 |
外科学 | 65篇 |
综合类 | 17篇 |
预防医学 | 100篇 |
眼科学 | 9篇 |
药学 | 50篇 |
中国医学 | 3篇 |
肿瘤学 | 76篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 30篇 |
2012年 | 32篇 |
2011年 | 32篇 |
2010年 | 35篇 |
2009年 | 32篇 |
2008年 | 34篇 |
2007年 | 43篇 |
2006年 | 45篇 |
2005年 | 43篇 |
2004年 | 22篇 |
2003年 | 31篇 |
2002年 | 30篇 |
2001年 | 19篇 |
2000年 | 32篇 |
1999年 | 25篇 |
1998年 | 26篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 19篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1969年 | 4篇 |
排序方式: 共有926条查询结果,搜索用时 15 毫秒
1.
2.
报道新化合物A-失碳-17β-羟基-17α-乙炔基-Δ3(5),9(10)-雌甾二烯-2-酮2的合成。文中探讨了用炔钾粗品对A-失碳-Δ3(5),9(10)-雌甾二烯-2,17-二酮1和A-失碳-6β,19-环氧-Δ3-雄甾-2,17-二酮3的选择性炔化,分别得标题化合物2(44%)及A-失碳-17β-羟基-17α-乙炔基-6β,19-环氧-Δ3雄甾-2-酮4(65%),4经还原性破开环氧、去羟甲基和去醋酰氧基合成了标题化合物2。四步总收率为34%。 相似文献
3.
Two modified helical basket extractors are described that have increased the success rate of removing ureteral calculi using fluoroscopy from 63% to 92%. Initially a rather stiff and expandable basket with a 20-cm filiform tip is used with coaxial catheters and sheath (stage 1). If this procedure is unsuccessful, a basket with two long cable ends is passed from the nephrostomy out through the urethra (stage 2). When used with coaxial bladder catheters, this technique allows dilatation of the vesicoureteric junction and retrograde catheterization and injection of fluids or gas to dislodge the stone prior to extraction. In a series of 38 patients, stones were removed in all but three (a success rate of 92%). In five cases small stones (less than 5 mm) were not retrieved but subsequent studies were normal. Ureteral stones were found in the abdominal ureter in 28 cases, in the pelvic ureter in seven cases, and in multiple sites in three cases. Stones were larger than 1 cm in 27.7% of cases. Postextraction mucosal edema with reduced ureteral patency was common but usually cleared in 2-3 days. Occasional complications were related to the nephrostomy. 相似文献
4.
S.L. Atkin A.M. Coady D. Horton N. Sutaria L. Sellars C. Walton 《Diabetic medicine》1995,12(3):267-270
A 15-year-old girl presented de novo in diabetic ketoacidosis having been comatose for 24 h (day 1). A CT scan and lumbar puncture performed on admission were normal and her conscious level slowly improved over several days. On day 7 she had central neurological signs of bilateral knee clonus and an extensor plantar response. In addition, she had developed lower motor neurological signs of an ulnar nerve palsy of the left forearm, and ulnar, median, and radial nerve palsies of the right forearm. Magnetic resonance imaging (MRI), performed on day 12, showed multiple small cerebral haematomata with appearances at least several days of age. The scattered lesions were localized particularly to the parieto-occipital region, with sparing of the basal ganglia and without cerebral oedema, a novel feature not previously described in juvenile ketoacidosis. Four months later there was minimal residual disability of her right arm. The clinical findings together with the MRI images suggested that the peripheral nerve and central lesions were temporally related, suggesting a common aetiology. However, it is likely that MRI showed cerebral lesions which may have been missed by the conventional CT scanning performed initially. 相似文献
5.
6.
7.
The comparison of disease risk in populations stratified by certain demographic variables provides important clues as to the underlying causes of disease. There are fundamental variations in the risk of occurrence of different cancers by gender, area of residence, and time of diagnosis. Men are, for instance, at considerably higher risk of developing most of the common cancers that occur in both sexes, and there are substantial variations in the occurrence of particular cancers in different regions of the World. This paper attempts to highlight some of these remarkable variations using cancer incidence data by sex, area of residence and year of diagnosis, emphasising the strong evidence that many of the contrasts can be appropriated to a number of modifiable “environmental” factors.Rates of cancer occurrence in the developed world are double that of less developed regions, although risk patterns are of very different magnitude and direction depending on the cancer site examined. Lung cancer is the most common neoplasm in men globally, but is overshadowed by prostate cancer in certain westernised countries, notably in the U.S. Cancers of the colon and rectum are important in the developed world, whereas stomach and liver cancer are common in developing areas.Men have systematically higher rates than women for the vast majority of the tumours that develop in both sexes, with the exception of thyroid cancer. There are also huge variations in the extent of the inequality: men have notably elevated risks, relative to women, of developing tumours of the head and neck, bladder, lung, oral cavity and liver.In Europe, incidence trends of lung cancer tend to be declining in men, although there is substantial between-country variation. In women, lung cancer rates are systematically on the increase in most Western, Southern and European countries. Trends in prostate cancer are increasing, as are trends in colorectal cancer (in both sexes), although more noticeably in Southern and Eastern Europe. Stomach cancer continues to fall in most European areas. Bladder cancer is decreasing in both men and women, apart from in Eastern Europe, whereas cancers of the kidney and non-Hodgkin lymphoma are steadily increasing in both sexes.We have estimated that men have better and more readily achievable prospects of avoiding death from cancer since they have lower rates of gender specific cancers, that are probably hormonal in origin, then women. Tobacco consumption plays a dominating role in the excess risk of cancer in men but it is apparent that the male excess disease burden can be effectively reduced by various prevention measures. As well as avoiding (or quitting) smoking, these include, moderating alcohol consumption, avoiding obesity, undertaking regular physical exercise, and maintaining a diet high in fruit and vegetables. The adoption of a healthier lifestyle will be of considerable benefit to the general health of both men and women, with an expectation of a major reduction in the burden of cancer, as well as other major diseases. 相似文献
8.
Retrorenal colon: implications for percutaneous diskectomy 总被引:1,自引:0,他引:1
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary. 相似文献
9.
10.
N.D. Stafford L.T. Condon M.J.C. Rogers A.W. MacDonald S.L. Atkin 《Clinical otolaryngology》2003,28(4):314-319
The expression of somatostatin receptors 1 and 2 in benign, pre‐malignant and malignant laryngeal lesions The role of chemotherapy in squamous cell carcinoma of the larynx has not been clearly defined. Whilst toxic chemotherapy regimes may confer a marginal improvement in survival, surgery and radiotherapy remain the mainstay of treatment. Somatostatin is a naturally occurring peptide, which exerts antiproliferative and antiangiogenic effects via five membrane‐bound receptor subtypes. The expression of somatostatin receptor subtypes (SSTRs) 1 and 2 was studied in benign, pre‐malignant and malignant laryngeal specimens. Epithelial expression of SSTR1 was detected in 4/6 (67%) Reinke's oedema, 5/6 (83%) pre‐malignant and 8/12 (67%) malignant specimens, with virtually no stromal or vascular expression. High levels of epithelial SSTR2 expression were noted in all Reinke's oedema specimens, compared with low‐to‐moderate levels in only 2/6 (33%) pre‐malignant and 3/12 (25%) malignant specimens (P < 0.01). This ‘loss’ of epithelial SSTR2 expression may provide a growth advantage in pre‐malignant and malignant laryngeal lesions. Vascular expression of SSTR2 was ubiquitous in all groups, with scant stromal expression. Overall, most (>80%) pre‐malignant and malignant laryngeal specimens expressed at least one of the two SSTR subtypes studied. Somatostatin analogues may have a therapeutic role in squamous cell carcinoma of the larynx. 相似文献