全文获取类型
收费全文 | 215471篇 |
免费 | 37122篇 |
国内免费 | 2526篇 |
专业分类
耳鼻咽喉 | 5981篇 |
儿科学 | 7174篇 |
妇产科学 | 4001篇 |
基础医学 | 14099篇 |
口腔科学 | 3213篇 |
临床医学 | 32872篇 |
内科学 | 60533篇 |
皮肤病学 | 8447篇 |
神经病学 | 20929篇 |
特种医学 | 9112篇 |
外国民族医学 | 45篇 |
外科学 | 49346篇 |
综合类 | 779篇 |
现状与发展 | 72篇 |
一般理论 | 89篇 |
预防医学 | 12153篇 |
眼科学 | 4569篇 |
药学 | 5774篇 |
中国医学 | 180篇 |
肿瘤学 | 15751篇 |
出版年
2024年 | 702篇 |
2023年 | 4957篇 |
2022年 | 1668篇 |
2021年 | 4131篇 |
2020年 | 6653篇 |
2019年 | 3130篇 |
2018年 | 8545篇 |
2017年 | 8130篇 |
2016年 | 9345篇 |
2015年 | 9509篇 |
2014年 | 16855篇 |
2013年 | 18022篇 |
2012年 | 8647篇 |
2011年 | 8807篇 |
2010年 | 12648篇 |
2009年 | 16095篇 |
2008年 | 8745篇 |
2007年 | 7118篇 |
2006年 | 9517篇 |
2005年 | 6714篇 |
2004年 | 6038篇 |
2003年 | 4720篇 |
2002年 | 4869篇 |
2001年 | 6033篇 |
2000年 | 5340篇 |
1999年 | 5230篇 |
1998年 | 4521篇 |
1997年 | 4202篇 |
1996年 | 4031篇 |
1995年 | 3893篇 |
1994年 | 2518篇 |
1993年 | 2174篇 |
1992年 | 2831篇 |
1991年 | 2792篇 |
1990年 | 2393篇 |
1989年 | 2496篇 |
1988年 | 2110篇 |
1987年 | 1958篇 |
1986年 | 1949篇 |
1985年 | 1690篇 |
1984年 | 1244篇 |
1983年 | 1169篇 |
1982年 | 977篇 |
1981年 | 845篇 |
1980年 | 745篇 |
1979年 | 933篇 |
1978年 | 707篇 |
1977年 | 755篇 |
1975年 | 660篇 |
1972年 | 649篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Toshio Imaizumi MD PhD Toshimi Honma MD PhD Yoshifumi Horita MD Ikuhide Kohama MD PhD Kei Miyata MD Maiko Kawamura MD Jun Niwa MD PhD 《Journal of neuroimaging》2006,16(3):236-242
BACKGROUND AND PURPOSE: Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. METHODS: To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH < or =2 cm was estimated, using the number of dotHSs and risk factors for stroke. RESULTS: The number of dotHSs associated with the diameter < or =2 cm was 9.2 +/- 11.5, significantly larger than that with the diameter > or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). CONCLUSION: Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH. 相似文献
132.
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
133.
134.
Robert J Derksen Fred C Bakker Emil A Heilbron Pieter C Geervliet Irma M Spaans Elly S M de Lange-de Klerk Bart Veenings Peter Patka Henk J Th M Haarman 《European journal of emergency medicine》2006,13(1):3-8
OBJECTIVES: In the quest for a cost-effective and quality-preserving solution to manage crowding in the emergency department, the possibility of deploying regular emergency nurses for the treatment of acute ankle injuries was investigated. The aim of this study is to compare the diagnostic accuracy of emergency nurses with that of senior house officers in interpreting ankle and foot radiographs. METHODS: A prospective study comparing the assessment of 60 radiographs (30 feet and 30 ankles) by 16 emergency nurses before and after an educational session was performed. Each subset of 30 radiographs contained 12 fractures, hand-picked by a radiologist to represent everyday traumatology in the emergency department. The control group consisted of eight senior house officers representing everyday expertise. The outcome of the diagnostic assessment, represented as the pooled sensitivity and specificity for both groups, was compared using Z-statistics. RESULTS: Before the training session, the specialized emergency nurse group showed a sensitivity of 0.87 (confidence interval 0.83-0.91) compared with 0.93 (confidence interval 0.88-0.96) for the control group (P = 0.05). The specificity of specialized emergency nurses was 0.87 (confidence interval 0.81-0.92) compared with 0.93 (confidence interval 0.89-0.95) for the senior house officers (P < 0.05). After the training session, specialized emergency nurse diagnostic parameters did not differ significantly from the control group, displaying a sensitivity of 0.89 (confidence interval 0.86-0.92) and specificity of 0.92 (confidence interval 0.87-0.95). CONCLUSION: Before the training session, the specialized emergency nurse group showed a significantly lower accuracy than the SHO group. After training, however, the diagnostic accuracy did not differ significantly between groups. Therefore, we conclude that emergency nurses are able to accurately interpret foot and ankle radiographs after a short educational session. 相似文献
135.
Lucia Nogovà MD Volker Diehl MD Andreas Engert MD 《Current hematologic malignancy reports》2006,1(1):60-65
Lymphocyte-predominant Hodgkin’s lymphoma (LPHL) differs in histologic and clinical presentation from classical Hodgkin’s
lymphoma (cHL). Treatment of LPHL patients using standard Hodgkin’s lymphoma protocols leads to complete remission in more
than 95% of patients. Survival and freedom from treatment failure are substantially worse in advanced-stage patients than
for early-stage patients. Thus, patients in advanced stages and those in early stages with unfavorable risk factors should
be treated similar to those with cHL. In contrast, patients with early-stage LPHL without risk factors might be sufficiently
treated with reduced-intensity programs having less severe adverse effects. As a result, treatment of early LPHL is rather
heterogeneous, including radiotherapy using extended-fleld technique, involved-fleld radiotherapy (IF-RT), combined-modality
treatment, and, more recently, monoclonal antibodies. Watch-and-wait strategy plays an important role in pediatric oncology,
to avoid adverse effects associated with therapy. IF-RT seems to be emerging as a treatment of choice for patients with stage
IA LPHL; most larger study groups, such as the German Hodgkin Study Group and the European Organisation for Research and Treatment
of Cancer, have adopted IF-RT as the treatment of choice for these patients. 相似文献
136.
137.
138.
139.
140.
Abstract: Data from the National Education Longitudinal Study were combined with census data at the zip code level to examine the impact of neighborhood racial and ethnic diversity and consolidated inequality, in addition to individual, family, and school factors, on the likelihood of dropping out of high school. Results indicate that while the effects for diversity and consolidated inequality did not support the stated hypotheses, main effects for family risk and prior academic achievement were significant and in the stated direction. Also, when controlling for individual, family, school, and neighborhood characteristics, African Americans were less likely than White students to drop out of school. Implications for contextual effects research and educational outcomes are discussed. 相似文献