全文获取类型
收费全文 | 4405篇 |
免费 | 393篇 |
国内免费 | 110篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 46篇 |
妇产科学 | 17篇 |
基础医学 | 379篇 |
口腔科学 | 89篇 |
临床医学 | 553篇 |
内科学 | 437篇 |
皮肤病学 | 27篇 |
神经病学 | 271篇 |
特种医学 | 727篇 |
外国民族医学 | 1篇 |
外科学 | 233篇 |
综合类 | 550篇 |
预防医学 | 530篇 |
眼科学 | 67篇 |
药学 | 650篇 |
中国医学 | 216篇 |
肿瘤学 | 99篇 |
出版年
2024年 | 5篇 |
2023年 | 70篇 |
2022年 | 111篇 |
2021年 | 278篇 |
2020年 | 199篇 |
2019年 | 233篇 |
2018年 | 226篇 |
2017年 | 211篇 |
2016年 | 199篇 |
2015年 | 165篇 |
2014年 | 312篇 |
2013年 | 359篇 |
2012年 | 258篇 |
2011年 | 309篇 |
2010年 | 197篇 |
2009年 | 189篇 |
2008年 | 189篇 |
2007年 | 156篇 |
2006年 | 152篇 |
2005年 | 116篇 |
2004年 | 113篇 |
2003年 | 93篇 |
2002年 | 72篇 |
2001年 | 56篇 |
2000年 | 55篇 |
1999年 | 47篇 |
1998年 | 39篇 |
1997年 | 38篇 |
1996年 | 45篇 |
1995年 | 46篇 |
1994年 | 41篇 |
1993年 | 30篇 |
1992年 | 39篇 |
1991年 | 32篇 |
1990年 | 26篇 |
1989年 | 19篇 |
1988年 | 27篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 26篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有4908条查询结果,搜索用时 78 毫秒
71.
使用随机系数模型估计医疗组织成员的学习率,衡量组织学习的绩效,并且实证性地采用中国台湾地区全民健康保险数据库,比较台湾医学中心医院对内视镜胆囊切除手术成本控制的学习绩效.通过研究的理论性与实证性,组织管理者可以从微观的角度了解到组织内部的学习能力与不同团体和组织之间的学习率差异. 相似文献
72.
《Gait & posture》2021
BackgroundAdequate footwear is an important factor for reducing the risk of slipping; as shoe outsoles wear down, friction decreases, and slip and fall risk increases. Wear theory suggests that gait kinetics may influence rate of tread wear.Research questionDo the kinetics of walking (i.e., the shoe-floor force interactions) affect wear rate?MethodsFourteen participants completed dry walking trials during which ground reaction forces were recorded across different types of shoes. The peak normal force, shear force, and required coefficient of friction (RCOF) were calculated. Participants then wore alternating pairs of shoes in the workplace each month for up to 24 months. A pedometer was used to track the distance each pair of shoes was worn and tread loss was measured. The wear rate was calculated as the volumetric tread loss divided by the distance walked in the shoes. Three, mixed linear regression models were used to assess the impact of peak normal force, shear force, and RCOF on wear rate.ResultsWear rate was positively associated with peak RCOF and with peak shear force, but was not significantly related to peak normal forces.SignificanceThe finding that shear forces and particularly the peak RCOF are related to wear suggests that a person’s gait characteristics can influence wear. Therefore, individual gait kinetics may be used to predict wear rate based on the fatigue failure shoe wear mechanism. 相似文献
73.
Xingchen Wu Seyoum Nerisho Prasun Dastidar Pertti Ryymin Ritva Järvenpää Hannu Pertovaara Hannu Eskola Pirkko‐Liisa Kellokumpu‐Lehtinen 《NMR in biomedicine》2013,26(9):1186-1194
To compare different MRI sequences for the detection of lesions and the evaluation of response to chemotherapy in patients with diffuse large B‐cell lymphoma (DLBCL), 18 patients with histology‐confirmed DLBCL underwent 3‐T MRI scanning prior to and 1 week after chemotherapy. The MRI sequences included T1‐weighted pre‐ and post‐contrast, T2‐weighted with and without fat suppression, and a single‐shot echo‐planar diffusion‐weighted imaging (DWI) with two b values (0 and 800 s/mm2). Conventional MRI sequence comparisons were performed using the contrast ratio between tumor and normal vertebral body instead of signal intensity. The apparent diffusion coefficient (ADC) of the tumor was measured directly on the parametric ADC map. The tumor volume was used as a reference for the evaluation of chemotherapy response. The mean tumor volume was 374 mL at baseline, and decreased by 65% 1 week after chemotherapy (p < 0.01). The T2‐weighted image with fat suppression showed a significantly higher contrast ratio compared with images from all other conventional MRI sequences, both before and after treatment (p < 0.01, respectively). The contrast ratio of the T2‐weighted image with fat suppression decreased significantly (p < 0.01), and that of the T1‐weighted pre‐contrast image increased significantly (p < 0.01), after treatment. However, there was no correlation between the change in contrast ratio and tumor volume. The mean ADC value was 0.68 × 10–3 mm2/s at baseline; it increased by 89% after chemotherapy (p < 0.001), and the change in ADC value correlated with the change in tumor volume (r = 0.66, p < 0.01). The baseline ADC value also correlated inversely with the percentage change in ADC after treatment (r = ?0.62, p < 0.01). In conclusion, this study indicates that T2‐weighted imaging with fat suppression is the best conventional sequence for the detection of lesions and evaluation of the efficacy of chemotherapy in DLBCL. DWI with ADC mapping is an imaging modality with both diagnostic and prognostic value that could complement conventional MRI. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
74.
M. Tang C. Yu P. Hu C. Wang J. Sheng S. Ma 《The British journal of oral & maxillofacial surgery》2018,56(9):854-858
The aim of this retrospective, single-centre study was to identify the risk factors for bleeding after dental extractions in patients aged over 60 who were being treated with antiplatelet drugs. A total of 338 patients who fulfilled the inclusion criteria were enrolled, and their personal and clinical details, and complications with bleeding after extraction, were retrieved and recorded. There were 182 men and 156 women (mean (SD) age 72 (8) years). A total of 469 teeth were extracted, with a mean (SD) of 1.4 (0.6) teeth/patient. Seventy-seven patients (23%) developed mild, and 55 (16%) severe, bleeding postoperatively. No patient developed a major cardiovascular or cerebrovascular event. We calculated the significance of the association of different variables with the occurrence of postoperative haemorrhage using a multivariate stepwise logistic regression model. The presence of three or more coexisting conditions, a complicated tooth extraction, and the use of two antiplatelet drugs were independent risk factors, while discontinuation of antiplatelet treatment four or more days before the tooth was extracted was a protective factor. This suggests that clinicians should assess the thrombotic risk associated with the interruption of antiplatelet drugs as well as the risk of bleeding for each patient before dental extraction. Strong and effective measures for haemostasis may be preferred over blind discontinuation of antiplatelet drugs. This study is registered in the Chinese Clinical Trial Registry (No. ChiCTR1800014355). 相似文献
75.
76.
A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. 相似文献
77.
Rajpaul Attariwala MD PhD FRCPC FANM Wayne Picker M. Hlth. Sc. 《Journal of magnetic resonance imaging : JMRI》2013,38(2):253-268
Diffusion‐weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole‐body MRI. Theory, b‐value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole‐body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b‐values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation. J. Magn. Reson. Imaging 2013;38:253–268. © 2013 Wiley Periodicals, Inc. 相似文献
78.
Myles T. Taffel Lyndon Luk Justin M. Ream Andrew B. Rosenkrantz 《Journal l'Association canadienne des radiologistes》2019,70(4):416-423
PurposeTo evaluate whole-lesion 3D-histogram apparent diffusion coefficient (ADC) metrics for assessment of pancreatic malignancy.MethodsForty-two pancreatic malignancies (36 pancreatic adenocarcinoma [PDAC], 6 pancreatic neuroendocrine [PanNET]) underwent abdominal magnetic resonance imaging (MRI) with diffusion-weighted imaging before endoscopic ultrasound biopsy or surgical resection. Two radiologists independently placed 3D volumes of interest to derive whole-lesion histogram ADC metrics. Mann-Whitney tests and receiver operating characteristic analyses were used to assess metrics’ diagnostic performance for lesion histology, T-stage, N-stage, and grade.ResultsWhole-lesion ADC histogram metrics lower in PDACs than PanNETs for both readers (P ≤ .026) were mean ADC (area under the curve [AUC] = 0.787-0.792), mean of the bottom 10th percentile (mean0-10) (AUC = 0.787-0.880), mean of the 10th-25th percentile (mean10-25) (AUC = 0.884-0.917) and mean of the 25th-50th percentile (mean25-50) (AUC = 0.829-0.829). For mean10-25 (metric with highest AUC for identifying PDAC), for reader 1 a threshold > 0.94 × 10?3 mm2/s achieved sensitivity 94% and specificity 83%, and for reader 2 a threshold > 0.82 achieved sensitivity 97% and specificity 67%. Metrics lower in nodal status ≥ N1 than N0 for both readers (P ≤ .043) were mean0-10 (AUC = 0.789-0.822) and mean10-25 (AUC = 0.800-0.822). For mean10-25 (metric with highest AUC for identifying N0), for reader 1 a threshold <1.17 achieved sensitivity 87% and specificity 67%, and for reader 2 a threshold <1.04 achieved sensitivity 87% and specificity 83%. No metric was associated with T-stage (P > .195) or grade (P > .215).ConclusionVolumetric ADC histogram metrics may serve as non-invasive biomarkers of pancreatic malignancy. Mean10-25 outperformed standard mean for lesion histology and nodal status, supporting the role of histogram analysis. 相似文献
79.
Vicent Caballer-Tarazona Natividad Guadalajara-Olmeda David Vivas-Consuelo 《Health policy (Amsterdam, Netherlands)》2019,123(4):427-434
Objectives
This article has two main purposes. Firstly, to model the integrated healthcare expenditure for the entire population of a health district in Spain, according to multimorbidity, using Clinical Risk Groups (CRG). Secondly, to show how the predictive model is applied to the allocation of health budgets.Methods
The database used contains the information of 156,811 inhabitants in a Valencian Community health district in 2013. The variables were: age, sex, CRG’s main health statuses, severity level, and healthcare expenditure. The two-part models were used for predicting healthcare expenditure. From the coefficients of the selected model, the relative weights of each group were calculated to set a case-mix in each health district.Results
Models based on multimorbidity-related variables better explained integrated healthcare expenditure. In the first part of the two-part models, a logit model was used, while the positive costs were modelled with a log-linear OLS regression. An adjusted R2 of 46–49% between actual and predicted values was obtained. With the weights obtained by CRG, the differences found with the case-mix of each health district proved most useful for budgetary purposes.Conclusions
The expenditure models allowed improved budget allocations between health districts by taking into account morbidity, as opposed to budgeting based solely on population size. 相似文献80.