全文获取类型
收费全文 | 51996篇 |
免费 | 3887篇 |
国内免费 | 202篇 |
学科分类
医药卫生 | 56085篇 |
出版年
2023年 | 648篇 |
2022年 | 481篇 |
2021年 | 2284篇 |
2020年 | 1429篇 |
2019年 | 1946篇 |
2018年 | 2254篇 |
2017年 | 1513篇 |
2016年 | 1670篇 |
2015年 | 1830篇 |
2014年 | 2289篇 |
2013年 | 2937篇 |
2012年 | 4689篇 |
2011年 | 4686篇 |
2010年 | 2397篇 |
2009年 | 2078篇 |
2008年 | 3342篇 |
2007年 | 3297篇 |
2006年 | 3089篇 |
2005年 | 2867篇 |
2004年 | 2555篇 |
2003年 | 2251篇 |
2002年 | 1929篇 |
2001年 | 340篇 |
2000年 | 283篇 |
1999年 | 326篇 |
1998年 | 386篇 |
1997年 | 287篇 |
1996年 | 176篇 |
1995年 | 193篇 |
1994年 | 142篇 |
1993年 | 130篇 |
1992年 | 129篇 |
1991年 | 119篇 |
1990年 | 102篇 |
1989年 | 106篇 |
1988年 | 80篇 |
1987年 | 62篇 |
1986年 | 71篇 |
1985年 | 68篇 |
1984年 | 59篇 |
1983年 | 62篇 |
1982年 | 37篇 |
1981年 | 47篇 |
1980年 | 34篇 |
1979年 | 42篇 |
1978年 | 28篇 |
1977年 | 34篇 |
1974年 | 23篇 |
1973年 | 34篇 |
1969年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
61.
62.
The clinical syndrome of tuberculous (TB) meningitis leading to ischemic strokes is rarely seen today in immunocompetent adults native to North America. This entity is also notoriously difficult to diagnose because the presenting symptoms are often nonspecific. The authors describe a case of a man with TB meningitis which progressed to recurrent ischemic cerebral infarcts. 相似文献
63.
Spinal cord stimulation (SCS) is widely used for pain relief in patients with failed back surgery syndrome (FBSS), and muscle weakness is a common finding in patients with chronic pain. We present here a single case report of a 47‐year‐old woman, who, after SCS for FBSS, had continuous improvement in lower leg muscle strength and gait, but only transient and minimal pain relief. To the authors’ knowledge, this is only the second published case report of significant improvement in “motor” function, independent of the analgesic effect following SCS in FBSS. If SCS, in fact, does improve muscle strength, new strategies for the management of patients with chronic pain might be opened up. Further studies are needed to verify this hypothesis. 相似文献
64.
Eileen Dauer John Salassa Laura Iuga Jan Kasperbauer 《Otolaryngology--head and neck surgery》2006,134(5):830-835
OBJECTIVE: To illustrate the safety and efficacy of the endoscopic laser approach for cricopharyngeal myotomy (CPM) compared to the traditional transcervical approach. STUDY DESIGN AND SETTING: Retrospective chart review of 22 patients undergoing CPM from 1996 to 2003 at the Mayo Clinic, Jacksonville. RESULTS: The laser CPM technique was used in 14 patients, and an open approach in 8. The mean hospital stay and operative times were shorter for the laser group. Functional outcome analyses showed improvement in both groups. There were no major complications in the laser group, while 1 patient in the transcervical group had a pharyngocutaneous fistula. CONCLUSIONS: The laser technique is at least as effective as the transcervical approach for CPM to improve dysphagia symptoms in the properly selected patient, with a low risk of major complications. SIGNIFICANCE: In this report, we provide the reader with data to support the safety and efficacy of laser CPM. EBM rating: B-3b. 相似文献
65.
Mary Ann Richardson Helen M Chao Laura L Read James D Clelland Raymond F Suckow 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2006,(2):195-197
Phenylketonuria (PKU), an inborn error of phenylalanine metabolism, has been shown to be a risk factor for tardive dyskinesia (TD). In male psychiatric patients there was a significant relationship between TD and measures of plasma phenylalanine following ingestion of a standardized phenylalanine dose that was indicative of higher brain availability of phenylalanine in patients with TD. In addition, a medical food formulation consisting of branched chain amino acids, which compete with phenylalanine for transport across the blood-brain barrier, has been demonstrated to be an efficacious treatment for TD. Cumulatively these findings suggested that TD was related to phenylalanine metabolism and thus that sequence variants in the gene for phenylalanine hydroxylase (PAH), the rate-limiting enzyme in the catabolism of phenylalanine, could be associated with TD susceptibility. Genetic screening of PAH in a group of 123 psychiatric patients revealed ten sequence polymorphisms and two mutations, but none appeared to be a significant risk factor for TD. 相似文献
66.
Estrogenic microenvironment generated by organochlorine residues in adipose mammary tissue modulates biomarker expression in ERα-positive breast carcinomas 下载免费PDF全文
67.
68.
69.
70.
Celia F Hybels Dan G Blazer Carl F Pieper Bruce M Burchett Judith C Hays Gerda G Fillenbaum Laura D Kubzansky Lisa F Berkman 《The American journal of geriatric psychiatry》2006,14(6):498-506
OBJECTIVE: Neighborhood sociodemographic characteristics may be important to the mental health of older adults who have decreased mobility and fewer resources. Our objective was to examine the association between neighborhood context and level of depressive symptomatology in older adults in a diverse geographic region of central North Carolina. METHODS: The sample included 2,998 adults 65 or older residing in 91 census tracts. Depressive symptoms were measured using the Center for Epidemiologic Studies-Depression scale (CES-D). Neighborhoods were characterized by five census-based characteristics: socioeconomic disadvantage, socioeconomic advantage, racial/ethnic heterogeneity, residential stability, and age structure. RESULTS: In ecologic level analyses, level of census tract socioeconomic disadvantage was associated with increased depressive symptoms. To determine whether neighborhood context was associated with depressive symptoms independently of individual characteristics, the authors used multilevel modeling. The authors examined the ability of each of five neighborhood (level 2) characteristics to predict a level 1 outcome (CES-D symptoms) controlling for the effects of individual (level 1) characteristics. Younger age, being widowed, lower income, and having some functional limitations were associated with increased depression symptoms conditional on census tract random effects. However, none of the neighborhood characteristics was significantly associated with depression symptoms, conditional on census tract random effects, either unadjusted or adjusted for individual characteristics. CONCLUSION: Any observed association between neighborhood sociodemographic characteristics and individual depressive symptoms in our sample may reflect the characteristics of the individuals who reside in the neighborhood rather than the neighborhood characteristics themselves. The use of multilevel modeling is important to separate these effects. 相似文献