全文获取类型
收费全文 | 7808篇 |
免费 | 513篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 184篇 |
妇产科学 | 179篇 |
基础医学 | 806篇 |
口腔科学 | 127篇 |
临床医学 | 977篇 |
内科学 | 1414篇 |
皮肤病学 | 62篇 |
神经病学 | 806篇 |
特种医学 | 261篇 |
外科学 | 790篇 |
综合类 | 169篇 |
一般理论 | 11篇 |
预防医学 | 1035篇 |
眼科学 | 139篇 |
药学 | 803篇 |
中国医学 | 9篇 |
肿瘤学 | 568篇 |
出版年
2024年 | 8篇 |
2023年 | 41篇 |
2022年 | 75篇 |
2021年 | 169篇 |
2020年 | 104篇 |
2019年 | 176篇 |
2018年 | 182篇 |
2017年 | 157篇 |
2016年 | 188篇 |
2015年 | 198篇 |
2014年 | 260篇 |
2013年 | 380篇 |
2012年 | 572篇 |
2011年 | 582篇 |
2010年 | 307篇 |
2009年 | 284篇 |
2008年 | 497篇 |
2007年 | 576篇 |
2006年 | 564篇 |
2005年 | 601篇 |
2004年 | 551篇 |
2003年 | 481篇 |
2002年 | 454篇 |
2001年 | 97篇 |
2000年 | 74篇 |
1999年 | 111篇 |
1998年 | 104篇 |
1997年 | 91篇 |
1996年 | 74篇 |
1995年 | 53篇 |
1994年 | 42篇 |
1993年 | 50篇 |
1992年 | 37篇 |
1991年 | 17篇 |
1990年 | 21篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 21篇 |
1985年 | 17篇 |
1984年 | 19篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 8篇 |
排序方式: 共有8380条查询结果,搜索用时 15 毫秒
21.
Tony M. Keaveny Tania P. Pinilla R. Paul Crawford David L. Kopperdahl Albert Lou 《Journal of orthopaedic research》1997,15(1):101-110
We sought to quantify the systematic and random errors associated with-artifacts in the platens compression test for trabecular bone. Our hypothesis was that while errors may depend on anatomic site, they do not depend on apparent density and therefore have substantial random components. Trabecular bone specimens were first tested nondestructively using newly developed accurate protocols and then were tested again using the platens compression test. Percentage differences in modulus between the techniques (bovine) proximal tibia [n = 18] and humerus [n = 17] and human lumbar spine, [n = 9] were in the range of 4-86%. These differences did not depend on anatomic site (p = 0.21) and were only weakly dependent on apparent density and specimen aspect ratio (r2 < 0.10). The mean percentage difference in modulus was 32.6% representing the systematic component of the end-artifact error. Neglecting the minor variations explained by density and specimen size (approximately 10%), an upper bound on the random error from end-artifacts in this experiment was taken as the SD of the modulus difference (±18.2%). Based on a synthesis of data taken from this study and from the literature, we concluded that the systematic underestimation error in the platens compression test can be only approximated and is in the range of 20-40%; the substantial random error (±12.5%) confounds correction, particularly when the sample size is small. These errors should be considered when interpreting results from the platens test, and more accurate testing techniques should be used when such errors are not acceptable. 相似文献
22.
Primary care referrals for lumbar spine radiography: diagnostic yield and clinical guidelines. 下载免费PDF全文
William Hollingworth Christopher J Todd Hugh King Tony Males Adrian K Dixon Kanti R Karia Ann Louise Kinmonth 《The British journal of general practice》2002,52(479):475-480
BACKGROUND: Primary care requests for radiographs of the lumbar spine have come under increasing scrutiny. Guidelines aiming to reduce unnecessary radiographs by limiting referrals to patients at high risk of serious disease have been widely distributed. Trial evidence suggests that guidelines can reduce radiography referrals. It is not clear whether this reduction has been achieved in routine practice. AIM: This study, using routine data, was conducted to measure trends in pnmary care referrals for lumbar spine radiography at two hospitals between 1994 and 1999. DESIGN OF STUDY: Analysis of primary care requests for lumbar spine radiography from computerised records. SETTING: Addenbrooke's Hospital, Cambridge (1 July 1994 to 30 June 1999), and Ipswich General Hospital (1 July 1995 to 30 June 1999), United Kingdom. METHOD: All primary care requests for lumbar radiography were identified electronically from computerised information systems. A random sample of 2100 radiography reports were classified according to clinical importance. These classifications were used to examine whether the proportion of radiographs demonstrating potentially more serious findings had increased between 1994 and 1999. RESULTS: There was no evidence that primary care referrals for radiography of the lumbar spine had decreased between 1994 and 1999 at either hospital. General practitioners did not progressively refer more high-risk patients for lumbar radiography. Only a small proportion of patients had important radiographic findings that might warrant specialist referral or specific therapy. CONCLUSION: The implementation of diagnostic guidelines offers much to the NHS. However in these two hospitals, the reduction in radiograph utilisation evident in trials was not achieved. Guideline development is a resource intensive process; distribution must be supported by more effective implementation strategies. 相似文献
23.
24.
Aspergillus osteomyelitis is a rare condition and is a recognized infection of the immunosuppressed. The pediatric cases that were documented suggest that in children, chronic granulomatous disease is the major underlying disease [Tack et al.1982 73(2):295–300, Baez-Escudero et al. 2000 Case report—primary sternal Aspergillus osteomyelitis. Infect Med 17(7):505–516]. We report an interesting case of Aspergillus osteomyelitis of the thumb in a 5-year-old boy with aplastic anemia. The infection progressed despite a combination of antifungal therapy with Voriconazole and surgical debridement. The thumb was amputated and the child recovered. This case highlights the difficulty in diagnosing Aspergillus osteomyelitis and also the failure of conventional management in this child, which resulted in the amputation of the thumb as a life-saving measure. We believe this to be the first case report of Aspergillus osteomyelitis in the thumb. 相似文献
25.
26.
27.
Measuring central corneal thickness with ultrasound pachymetry. 总被引:2,自引:0,他引:2
PURPOSE: To determine how many ultrasound pachymetry measurements are required to obtain a reasonable estimate of central corneal thickness. METHODS: Five central corneal thickness measurements were obtained from each eye of 101 patients with normal corneas. The means of fewer than five readings were compared with the mean of five values for each eye to determine the incremental clinical value of additional measurements. RESULTS: Compared with the mean of five values, fewer than three measurements per eye provided a mean central corneal thickness value with inadequate confidence. Conversely, means of more than three readings provided little additional confidence over means of three values. CONCLUSIONS: Central corneal thickness by ultrasound pachymetry can be adequately assessed in the majority of eyes by taking three measurements per eye. 相似文献
28.
29.
30.