全文获取类型
收费全文 | 33741篇 |
免费 | 10108篇 |
国内免费 | 131篇 |
专业分类
耳鼻咽喉 | 391篇 |
儿科学 | 843篇 |
妇产科学 | 1967篇 |
基础医学 | 448篇 |
口腔科学 | 1522篇 |
临床医学 | 19137篇 |
内科学 | 5858篇 |
皮肤病学 | 644篇 |
神经病学 | 2753篇 |
特种医学 | 695篇 |
外科学 | 3248篇 |
综合类 | 99篇 |
现状与发展 | 2篇 |
预防医学 | 3888篇 |
眼科学 | 369篇 |
药学 | 256篇 |
中国医学 | 4篇 |
肿瘤学 | 1856篇 |
出版年
2024年 | 184篇 |
2023年 | 1886篇 |
2022年 | 387篇 |
2021年 | 864篇 |
2020年 | 1606篇 |
2019年 | 634篇 |
2018年 | 2330篇 |
2017年 | 2662篇 |
2016年 | 2702篇 |
2015年 | 2803篇 |
2014年 | 3143篇 |
2013年 | 3328篇 |
2012年 | 1017篇 |
2011年 | 1312篇 |
2010年 | 2011篇 |
2009年 | 2641篇 |
2008年 | 1145篇 |
2007年 | 856篇 |
2006年 | 983篇 |
2005年 | 708篇 |
2004年 | 612篇 |
2003年 | 535篇 |
2002年 | 452篇 |
2001年 | 696篇 |
2000年 | 396篇 |
1999年 | 621篇 |
1998年 | 803篇 |
1997年 | 930篇 |
1996年 | 892篇 |
1995年 | 786篇 |
1994年 | 547篇 |
1993年 | 458篇 |
1992年 | 348篇 |
1991年 | 314篇 |
1990年 | 296篇 |
1989年 | 259篇 |
1988年 | 205篇 |
1987年 | 178篇 |
1986年 | 166篇 |
1985年 | 183篇 |
1984年 | 137篇 |
1983年 | 124篇 |
1982年 | 104篇 |
1981年 | 107篇 |
1980年 | 65篇 |
1979年 | 85篇 |
1978年 | 71篇 |
1977年 | 74篇 |
1976年 | 72篇 |
1972年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
51.
52.
53.
54.
55.
56.
57.
58.
59.
The purpose of this study was to investigate radiographic measurements in a cohort of patients with juvenile hallux valgus (with a hallux valgus angle > 15 degrees ) using standardized weightbearing x-rays compared with an age-matched control group. First metatarsal protrusion distance, metatarsus primus adductus angle, metatarsus adductus, first metatarsal cuneiform angle, calcaneal inclination angle, and talocalcaneal angles were assessed with discriminant functional analysis. A total of 37 sets of data were analyzed from patients with a mean age of 13.45 +/- 1.75 years. The study identified 2 significant components of juvenile hallux valgus: a positive first metatarsal protrusion distance (P <.001) and metatarsal primus adductus angle (P = .002). Discriminant functional analysis was then used to determine the best predictors of juvenile hallux valgus. This analysis allowed only 1 variable, metatarsal protrusion distance, as a predictor of whether juvenile hallux valgus was present (P < .001), with 94.3% accuracy. This study showed that a positive metatarsal protrusion distance is a significant component of juvenile hallux valgus. 相似文献
60.
Maher Saqqur MD Michael D. Hill MD MSc FRCPC Andrei V. Alexandrov MD Jayanta Roy MD Marcia Schebel BSc Andrea Krol BSc Zsolt Garami MD Ashfaq Shuaib MD FRCPC Andrew M. Demchuk MD FRCPC 《Journal of neuroimaging》2006,16(4):323-328
BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies. 相似文献