全文获取类型
收费全文 | 932191篇 |
免费 | 64274篇 |
国内免费 | 2397篇 |
专业分类
耳鼻咽喉 | 12751篇 |
儿科学 | 29674篇 |
妇产科学 | 26818篇 |
基础医学 | 131681篇 |
口腔科学 | 24950篇 |
临床医学 | 77837篇 |
内科学 | 190777篇 |
皮肤病学 | 19678篇 |
神经病学 | 74377篇 |
特种医学 | 37355篇 |
外国民族医学 | 363篇 |
外科学 | 146077篇 |
综合类 | 19183篇 |
一般理论 | 251篇 |
预防医学 | 66979篇 |
眼科学 | 20619篇 |
药学 | 66085篇 |
中国医学 | 1874篇 |
肿瘤学 | 51533篇 |
出版年
2018年 | 10020篇 |
2017年 | 7849篇 |
2016年 | 8339篇 |
2015年 | 9568篇 |
2014年 | 13209篇 |
2013年 | 20511篇 |
2012年 | 28027篇 |
2011年 | 29577篇 |
2010年 | 17692篇 |
2009年 | 16626篇 |
2008年 | 28235篇 |
2007年 | 29900篇 |
2006年 | 29942篇 |
2005年 | 29540篇 |
2004年 | 28342篇 |
2003年 | 27360篇 |
2002年 | 26883篇 |
2001年 | 42098篇 |
2000年 | 43328篇 |
1999年 | 36872篇 |
1998年 | 10120篇 |
1997年 | 9250篇 |
1996年 | 9192篇 |
1995年 | 8548篇 |
1994年 | 8171篇 |
1993年 | 7657篇 |
1992年 | 28519篇 |
1991年 | 27289篇 |
1990年 | 26699篇 |
1989年 | 25631篇 |
1988年 | 23804篇 |
1987年 | 23410篇 |
1986年 | 22494篇 |
1985年 | 21379篇 |
1984年 | 15967篇 |
1983年 | 13613篇 |
1982年 | 8163篇 |
1979年 | 14710篇 |
1978年 | 10275篇 |
1977年 | 8697篇 |
1976年 | 8212篇 |
1975年 | 9022篇 |
1974年 | 10793篇 |
1973年 | 10267篇 |
1972年 | 9746篇 |
1971年 | 9007篇 |
1970年 | 8674篇 |
1969年 | 8123篇 |
1968年 | 7773篇 |
1967年 | 7163篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Rènée du Toit Katherine Soong Garry Brian Jacqueline Ramke 《Optometry and vision science》2006,83(8):582-588
PURPOSE: The advantages of a focometer (FOCOMETER) over other methods of refraction for use in developing countries are that it is lightweight, compact, relatively inexpensive, fairly quick, and easy to use with minimal training. This clinical trial compared the repeatability, validity, and ease of use of the focometer with an autorefractor. METHODS: The refractive status of the right eye of 80 participants was determined with an autorefractor (Canon RK3). Three measurements were also taken with the focometer. RESULTS: The spherical equivalent (M) of the focometer was 0.25 D more positive than the autorefractor (p < 0.001) and 84% of measurements were within 0.75 D of the autorefractor. The autorefractor detected astigmatism in 91% (73) of the eyes, whereas the focometer identified only 32% (26). The design of the clock target restricts cylinder axis accuracy to the nearest 15 degrees . There was evidence of a learning effect for the focometer: the second and third measurements were more repeatable in the untrained group. There were no differences between the mean (1.03 +/- 2.28) and third focometer (-1.05 +/- 2.32) measurements (p = 0.34). However, using the third focometer measurement, 94% of participants had visual acuities of at least 6/12(-2). CONCLUSIONS: This study highlighted the focometer's restricted power range, inaccuracy of astigmatism and axis determination, and dependence on subject understanding and compliance. Therefore, in most clinical settings, the focometer would not be adequate for quantifying refractive error, but the focometer spherical equivalent was within acceptable limits of the autorefractor, and the visual acuity with lenses determined by the focometer indicates its potential usefulness in public health settings, especially where only spherical ready-made spectacles are dispensed. There may be more cost-effective ways to determine refractive error in these circumstances. A potentially important enhancement in focometer methodology that improves its ease of use was identified: use only the third measurement for each eye. 相似文献
53.
54.
55.
56.
57.
To examine the prevalence of Internet sex networking among men who have sex with men (MSM) in Hong Kong and risk behaviors associated with the behavior, a telephone survey of 15,230 Hong Kong Chinese men aged 18-60 was conducted. Of the 283 active MSM (having engaged in some MSM behaviors in the last 6 months) identified, 17.7% had networked for MSM partners via the Internet in the last 6 months. Younger age (odds ratio [OR] for age < or = 25 vs. age >25 = 4.67, 95% confidence interval [CI] = 2.35-9.28) and being an anal-sex MSM (OR = 4.72, 95% CI=2.36-9.44) were independent predictors of Internet sex networking. Being an Internet sex networker was associated with some risk behaviors such as having contracted a sexually transmitted disease (adjusted OR = 4.79, 95% CI = 1.34-17.11), having had > or = 3 MSM partners (adjusted OR = 4.74, 95% CI = 2.20-10.23), and having engaged in anal sex (adjusted OR = 3.95, 95% CI = 1.89-8.23). HIV prevention programs for MSM should thereby include Internet-based interventions. 相似文献
58.
59.
60.
P F Plouin D L Clement H Boccalon J Dormandy I Durand-Zaleski G Fowkes L Norgren T Brown 《International angiology》2003,22(4):333-339
Atherosclerotic renal artery stenosis (ARAS) may cause hypertension, progressive renal failure, and recurrent pulmonary edema. It typically occurs in high risk patients with coexistent vascular disease elsewhere. Most patients with ARAS are likely to die from coronary heart disease or stroke before end-stage renal failure occurs. Recent controlled trials have shown that most patients undergoing angioplasty to treat renovascular hypertension still need antihypertensive agents 6 or 12 months after the procedure. Nevertheless, the number of antihypertensive agents required to control blood pressure adequately is lower following angioplasty than for medication alone. Trials assessing the value of revascularization for preserving renal function or preventing clinical events are only in the early recruitment phase. Revascularization should be undertaken in patients with ARAS and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition. With or without revascularization, medical therapy using antihypertensive, hypolipidemic and antiplatelet agents is necessary in almost all cases. 相似文献