全文获取类型
收费全文 | 991篇 |
免费 | 65篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 60篇 |
妇产科学 | 4篇 |
基础医学 | 170篇 |
口腔科学 | 10篇 |
临床医学 | 80篇 |
内科学 | 163篇 |
皮肤病学 | 7篇 |
神经病学 | 116篇 |
特种医学 | 103篇 |
外国民族医学 | 3篇 |
外科学 | 143篇 |
综合类 | 37篇 |
预防医学 | 37篇 |
眼科学 | 6篇 |
药学 | 57篇 |
中国医学 | 2篇 |
肿瘤学 | 64篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 31篇 |
2020年 | 30篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 32篇 |
2015年 | 40篇 |
2014年 | 45篇 |
2013年 | 50篇 |
2012年 | 80篇 |
2011年 | 72篇 |
2010年 | 53篇 |
2009年 | 42篇 |
2008年 | 44篇 |
2007年 | 47篇 |
2006年 | 41篇 |
2005年 | 53篇 |
2004年 | 50篇 |
2003年 | 38篇 |
2002年 | 30篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 16篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 2篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1976年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1961年 | 1篇 |
1928年 | 1篇 |
1915年 | 1篇 |
排序方式: 共有1068条查询结果,搜索用时 31 毫秒
61.
62.
OBJECTIVE: B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), although promising as biomarkers for heart failure, are affected by multiple confounders. The purpose of this article is to review the literature on the utility of BNP and NT-proBNP as biomarkers, with a focus on their role in critical illness and pulmonary diseases. DATA SOURCE: Published articles on BNP and NT-proBNP. DATA ANALYSIS: Multiple disorders in the intensive care unit cause elevated BNP and NT-proBNP levels, including cardiac diseases, shock, pulmonary hypertension, acute respiratory distress syndrome, acute pulmonary embolism, chronic obstructive pulmonary disease, renal failure, and other conditions. CONCLUSIONS: Intensivists and pulmonologists should understand that BNP and NT-proBNP levels might be raised to different degrees not only in heart failure but also in critical illness and various pulmonary diseases; in these situations, BNP and NT-proBNP may also serve as markers of severity and prognosis. 相似文献
63.
Apolipoprotein J (apoJ), also known as clusterin and SP-40,40, binds soluble beta-amyloid (Abeta and is up-regulated in the Alzheimer's disease (AD) brain. In the present study we classified apoJ-immunopositive Abeta deposits in AD temporal cortex, and found apoJ-immunoreactive plaques were often associated with dystrophic neurites. Quantitative immunohistochemical analysis of five AD brains showed that 29% of Abeta deposited in the parenchyma was associated with apoJ. Of Abeta deposits with apoJ immunopositivity, 71% were associated with phospho-tau-positive dystrophic neurites in the surrounding tissue. Conversely, 64% of phospho-tau-labeled neuritic deposits were labeled with apoJ. ApoJ was found at the core of these deposits, and co-localized with the amyloid staining agent thioflavine-S. To test the direct effects of apoJ on tau metabolism, we treated cells in culture with apoJ-containing conditioned media, and we injected apoJ-containing media into the rat hippocampus. Using both systems, we observed increases in levels of tau and phosphorylated tau. Our findings demonstrate that apoJ immunopositivity strongly correlates with the presence of amyloid and associated neuritic dystrophy in the neuropil of AD temporal cortex, and supports a model where extracellular apoJ facilitates the conversion of diffuse Abeta deposits into amyloid and enhances tau phosphorylation in neurites surrounding these of plaques. 相似文献
64.
We aimed in this study to assess the clinical usefulness of fractional anisotropy (FA) maps in the evaluation of lacunar infarctions in striatum, internal capsule and thalamus. We retrospectively reviewed 28 patients (18 men, 10 women; mean age 63 years) who had acute lacunar infarction in striatum, internal capsule and thalamus on diffusion weighted MR imaging (DWI). Fractional anisotropy (FA) maps were generated in addition to conventional T2 weighted images (T2WI) and trace maps of DWI. Two radiologists reviewed the location of infarcts in combination with and without FA maps. Exact location of infarction was determined by FA maps, i.e. on the white band of internal capsule or outside the internal capsule. Accuracy and inter-observer agreement on determination of the location of infarction was evaluated. Accuracy of infarct localization by T2WI-DWI only was varied from 72 to 91% according to the observers. Inter-observer agreement value was moderate (Kappa=0.446), when images were interpreted by T2WI-DWI only. Clinical manifestation of each lesions were varied, but sensory motor stroke was mainly observed in thalamic lesion (50%), while pure motor hemiparesis was predominant in the case of infarct involving internal capsule, corona radiata (91%) and basal ganglia (83%). The FA map is useful in the evaluation of lacunar lesions in striatum, internal capsule and thalamus. Clinical presentation varies according to the exact location of lacunar infarctions, and more accurate diagnosis can be made by FA maps as well as conventional T2-weighted image and DWI. 相似文献
65.
Informed consent was obtained from all patients before participation; study was approved by institutional review board. Three-dimensional (3D) gradient-echo magnetic resonance sequences can be optimized for rapid acquisition through asymmetric k-space sampling and interpolation of image data. A T1-weighted volumetric interpolated brain examination sequence (acquisition time, 1 minute 24 seconds) was prospectively compared qualitatively and quantitatively with magnetization-prepared rapid acquisition gradient-echo sequence (acquisition time, 6 minutes 6 seconds) for venography of cerebral venous structures in 21 female and seven male consecutive patients (mean age, 52.9 years; range, 16-81 years). Although signal- and contrast-to-noise ratios were substantially lower for volumetric interpolated sequence, difference in the subjective quality of visualization of cerebral venous structures was not significant (P >.05). Volumetric interpolated brain examination seems promising as a more time-efficient alternative for 3D imaging of cerebral venous structures. 相似文献
66.
OBJECTIVES: We tried to evaluate the feasibility and effectiveness of ureteroscopic lithotripsy under local anesthesia. METHODS: We evaluated the results of ureteroscopic lithotripsy under local anesthesia performed on 200 patients (male 91; female 109). We compared the pain perception during local ureteroscopic procedure to that of cystoscopy using a visual analogue pain scale recorded by the patient. RESULTS: The overall success rate was 93% (185/200). The success rates of the upper, mid and lower ureteral calculi were 83% (5/6), 78% (14/18), and 94% (166/176), respectively. The success rate was 94% (166/176) in calculi less than 10 mm, and 86% (30/35) in those more than 10 mm. There were 5 cases (3%) of complications: ureteral injury (1), pyelonephritis (2), and ureteral stricture (2). Although the mean pain scale score was higher in the ureteroscopy group (3.36+/-1.75) than in the cystoscopy group (3.13+/-1.92), the difference between the two groups was not statistically significant (p>0.05). Most of the patients tolerated pain during the procedure and only two patients required general anesthesia. Postoperative pain was also tolerable in most patients and only 8 (4%) patients required additional analgesics after the procedure. CONCLUSION: As the effectiveness and morbidity of ureteroscopic lithotripsy under local anesthesia are comparable to those of many other previous reports and as most of the patients could tolerate the pain of the procedure, we suggest that ureteroscopic lithotripsy can be performed effectively and safely under local anesthesia. 相似文献
67.
Ischemic cardiomyopathy: value of different MRI techniques for prediction of functional recovery after revascularization 总被引:7,自引:0,他引:7
OBJECTIVE: The purpose of this study was to compare the value of different MRI techniques for the assessment of myocardial viability. SUBJECTS AND METHODS. Eighteen infarct patients (mean age +/- SD, 62 +/- 8 years) with myocardial ischemia were examined using MRI before and after revascularization. The MRI study before treatment consisted of an evaluation of first-pass perfusion, contractile function at rest and during dobutamine stress, and delayed hyperenhancement. Findings were correlated with segmental and global cardiac function after revascularization. RESULTS: In initially dysfunctional segments, the likelihood of functional recovery after revascularization was 91% for segments without delayed hyperenhancement, 43% for segments with delayed hyperenhancement with transmural extent of 75% or less, and 8% for segments with delayed hyperenhancement with transmural extent of more than 75% (p < 0.05). Improved function at dobutamine stress MRI indicated functional recovery in 87%, whereas functional recovery was observed in only 30% of segments not responding at dobutamine stress MRI (p < 0.05). No significant correlation was found between the results of first-pass perfusion MRI and functional recovery. The ejection fraction after revascularization was best predicted by the MRI-derived infarct volume (p < 0.001, R(2) = 0.63). CONCLUSION: A simple protocol consisting of baseline contractility and delayed enhancement MRI studies is adequate to differentiate dysfunctional but viable from nonviable myocardium. Dobutamine stress and perfusion MRI studies offer little or no additional information. 相似文献
68.
Levy JI Welker-Hood LK Clougherty JE Dodson RE Steinbach S Hynes HP 《Environmental health : a global access science source》2004,3(1):13
Background
Children in urban public housing are at high risk for asthma, given elevated environmental and social exposures and suboptimal medical care. For a multifactorial disease like asthma, design of intervention studies can be influenced by the relative prevalence of key risk factors. To better understand risk factors for asthma morbidity in the context of an environmental intervention study, we conducted a detailed baseline evaluation of 78 children (aged 4–17 years) from three public housing developments in Boston. 相似文献69.
Jung HL Wang KC Kim SK Sung KW Koo HH Shin HY Ahn HS Shin HJ Cho BK 《Journal of neuro-oncology》2004,67(1-2):41-46
Cytogenetic and molecular genetic studies have shown that deletions on the short arm of chromosome 17 distal to p53 locus are the most common genetic events in medulloblastoma. We examined the occurrences and frequencies of allelic deletions on chromosome 17p13.1-13.3 by loss of heterozygosity (LOH) analysis to investigate the possible involvement of 17p13.1-13.3 in medulloblastoma development. We also performed survival analysis to determine whether LOH analysis of 17p13.1-13.3 can be used to predict prognosis in medulloblastoma. Loss of heterozygosity was analyzed by polymerase chain reaction on chromosome 17p13.1-13.3 using three microsatellite markers, TP53 on 17p13.1, D17S796 on 17p13.1-13.2, and D17S1574 on 17p13.3, in 17 medulloblastoma DNAs extracted either from archival tissue or fresh frozen tissue specimens. Allelic deletions were detected in five of 17 informative cases (29%) on TP53, eight of 17 informative cases (47%) on D17S796, and four of 17 informative cases (24%) on D17S1574. Overall, nine of 17 cases (53%) showed LOH on chromosome 17p13.1-13.3. The 5-year progression free survival (PFS) and 5-year overall survival rates were identical (59%). The 5-year PFS for nine medulloblastoma patients with LOH on 17p13.1-13.3 was 56%, and the 5-year PFS for eight medulloblastoma patients without LOH on 17p13.1-13.3 was 63%. In our survival analysis, we did not find a significant association between survival and LOH on 17p13.1-13.3. Our results support the notion that deletions of chromosome 17p13.1-13.3 may be involved in the pathogenesis of medulloblastoma. From survival analysis, we conclude that LOH on chromosome 17p13.1-13.3 may not be a significant predictor of prognosis in medulloblastoma. 相似文献
70.
Effects of diabetes mellitus on astrocyte GFAP and glutamate transporters in the CNS 总被引:3,自引:0,他引:3
Diabetes mellitus increases the risk of central nervous system (CNS) disorders such as stroke, seizures, dementia, and cognitive impairment. The cellular mechanisms responsible for the increased risk of these disorders are incompletely understood. Astrocytes are proving critical for normal CNS function, and alterations in their activity could contribute to diabetes-related disturbances in the brain. We examined the effects of streptozotocin (STZ)-induced diabetes in rats on the level of the astrocyte intermediate filament protein, glial fibrillary acidic protein (GFAP), number of astrocytes, and levels of the astrocyte glutamate transporters, glutamate transporter-1 (GLT-1) and glutamate/aspartate transporter (GLAST), in the cerebral cortex, hippocampus, and cerebellum by Western blotting (WB) and immunohistochemistry (IH). Studies were carried out at 4 and 8 weeks of diabetes duration. Diabetes resulted in a significant decrease in GFAP protein levels (WB) in the hippocampus and cerebellum at 4 weeks and in the cerebral cortex, hippocampus and cerebellum by 8 weeks. Attenuated GFAP immunoreactivity (IH) was evident in the hippocampus, cerebellum and white matter regions such as the corpus callosum and external capsule at both 4 and 8 weeks of diabetes. Astrocyte cell counts of adjacent sections immunoreactive for S-100B were not different between control and diabetic animals. No significant differences were noted in astrocyte glutamate transporter levels in the cerebral cortex, hippocampus, or cerebellum at either time period (WB, IH). With the expanding list of astrocyte functions in the CNS, the role of astrocytes in diabetes-induced CNS disorders clearly warrants further investigation. 相似文献