全文获取类型
收费全文 | 137836篇 |
免费 | 12371篇 |
国内免费 | 3631篇 |
专业分类
耳鼻咽喉 | 1064篇 |
儿科学 | 1938篇 |
妇产科学 | 1378篇 |
基础医学 | 12238篇 |
口腔科学 | 4561篇 |
临床医学 | 22093篇 |
内科学 | 15234篇 |
皮肤病学 | 1457篇 |
神经病学 | 12073篇 |
特种医学 | 24894篇 |
外国民族医学 | 304篇 |
外科学 | 12379篇 |
综合类 | 18102篇 |
现状与发展 | 11篇 |
预防医学 | 5172篇 |
眼科学 | 1947篇 |
药学 | 8122篇 |
72篇 | |
中国医学 | 3972篇 |
肿瘤学 | 6827篇 |
出版年
2024年 | 134篇 |
2023年 | 1988篇 |
2022年 | 2810篇 |
2021年 | 4812篇 |
2020年 | 4931篇 |
2019年 | 4720篇 |
2018年 | 4741篇 |
2017年 | 4865篇 |
2016年 | 5152篇 |
2015年 | 5109篇 |
2014年 | 12325篇 |
2013年 | 11270篇 |
2012年 | 9332篇 |
2011年 | 9727篇 |
2010年 | 9583篇 |
2009年 | 9356篇 |
2008年 | 7627篇 |
2007年 | 6447篇 |
2006年 | 5622篇 |
2005年 | 4922篇 |
2004年 | 4196篇 |
2003年 | 3399篇 |
2002年 | 2688篇 |
2001年 | 2526篇 |
2000年 | 2022篇 |
1999年 | 1631篇 |
1998年 | 1458篇 |
1997年 | 1363篇 |
1996年 | 1146篇 |
1995年 | 1146篇 |
1994年 | 956篇 |
1993年 | 790篇 |
1992年 | 685篇 |
1991年 | 598篇 |
1990年 | 493篇 |
1989年 | 373篇 |
1988年 | 370篇 |
1987年 | 318篇 |
1986年 | 254篇 |
1985年 | 301篇 |
1984年 | 263篇 |
1983年 | 189篇 |
1982年 | 203篇 |
1981年 | 214篇 |
1980年 | 175篇 |
1979年 | 128篇 |
1978年 | 107篇 |
1977年 | 77篇 |
1976年 | 103篇 |
1975年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
73.
目的 分析超声及应变式弹性成像预测超声引导下置入腘静脉血管鞘治疗下肢深静脉血栓形成(DVT)成功与否的价值。方法 回顾性分析103例接受超声引导下置入患侧腘静脉血管鞘的DVT患者的术前超声资料,比较置入血管鞘失败与成功病例腘静脉超声及应变式弹性成像表现差异;绘制差异有统计学意义超声参数的受试者工作特征曲线,获得其预测血管鞘置入失败的阈值,对每个参数阈值赋值1分,得到联合超声评分,以实际置入结果为标准,评价超声单一参数及联合评分的预测效能。结果 103例中,对100例行单侧、3例行双侧腘静脉置入血管鞘,包括左侧腘静脉71支、右侧35支,共106支腘静脉;对其中95支腘静脉置入血管鞘成功(成功组),11支失败(失败组)。相比成功组,失败组腘静脉内径及腘静脉与腘动脉内径比值均较小,血栓为等或高回声,与血管壁边界模糊,腘静脉应变式弹性评分为硬。以超声单一参数及联合评分预测置入血管鞘成功与否的曲线下面积分别为0.909、0.926、0.865、0.899、0.958及0.940(P均<0.001)。结论 患侧腘静脉超声及应变式弹性成像能有效预测对下肢DVT患者行超声引导下置入腘静脉血管鞘成功与否。 相似文献
74.
目的基于功能磁共振成像分析肝豆状核变性(Wilson disease, WD)患者纹状体亚区神经功能损害及其与临床相关分析,探讨其神经心理学症状可能的致病机制。方法收集WD患者29例和健康志愿者30例,进行3.0 T磁共振功能磁共振成像及临床量表测试,采用mICA工具箱的group ICA功能将壳核和尾状核分成8个亚区,做全脑功能连接,提取功能连接异常区域的值与临床量表测试结果做相关性分析。结果与对照组相比,WD患者左侧尾状核中部与全脑未发现功能增强或减弱区域,余感兴趣区与全脑功能连接不同程度减弱。左侧尾状核前部(ROI5)-中扣带回功能连接值与简易智能状态量表(MMSE)值呈显著负相关(r=-0.47,P=0.009);右侧尾状核前部(ROI6)-中扣带回功能连接值与MMSE值呈显著负相关(r=-0.46,P=0.011);右侧尾状核中部(ROI8)-右侧岛叶功能连接值与MMSE值呈显著负相关(r=-0.38,P=0.041)。结论右侧尾状核前中部与背外侧前额叶功能连接减弱,双侧壳核前部与丘脑功能连接减弱,可能破坏皮质-纹状体-丘脑回路引起认知功能损害;参与记忆及动作相关认知的突显网络、默认模式网络的通路连接受阻则可能是WD患者认知障碍的神经病理机制。 相似文献
75.
This study explores the feasibility of using diffusion kurtosis imaging (DKI) in the pelvic floor region and assesses the water diffusivity of the pubovisceral muscle. Twenty-seven healthy young nulliparous females underwent DKI at 3.0 T that included 15 gradient directions and three b values (0, 750, and 1500 s/mm2). The diffusion tensor and diffusion kurtosis metrics values of the pubovisceral muscle were measured after image processing. Two independent sample t-tests, a paired-samples t-test, and a nonparametric hypothesis test were performed as appropriate to compare the differences among different metrics. Twenty-six subjects (mean ± standard deviation age, 25 ± 2 years) were successfully analyzed by measuring the diffusion tensor and diffusion kurtosis metrics of the bilateral pubovisceral muscles. The metrics included mean kurtosis, axial kurtosis, radial kurtosis, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. We found no statistically significant differences for these measurement values between the left and right pubovisceral muscles (p = 0.271–0.931). However, radial kurtosis was greater than axial kurtosis in both pubovisceral muscles (p < 0.001) and axial diffusivity was lower than radial diffusivity in both pubovisceral muscles (p < 0.001). We deem the application of DKI technology to the pelvic floor region to be feasible. 相似文献
76.
Yicheng Chen Ozan Genc Clare B. Poynton Suchandrima Banerjee Christopher P. Hess Janine M. Lupo 《NMR in biomedicine》2022,35(5):e4666
Quantitative susceptibility mapping (QSM) has the potential for being a biomarker for various diseases because of its ability to measure tissue susceptibility related to iron deposition, myelin, and hemorrhage from the phase signal of a T2*-weighted MRI. Despite its promise as a quantitative marker, QSM is faced with many challenges, including its dependence on preprocessing of the raw phase data, the relatively weak tissue signal, and the inherently ill posed relationship between the magnetic dipole and measured phase. The goal of this study was to evaluate the effects of background field removal and dipole inversion algorithms on noise characteristics, image uniformity, and structural contrast for cerebral microbleed (CMB) quantification at both 3T and 7T. We selected four widely used background phase removal and five dipole field inversion algorithms for QSM and applied them to volunteers and patients with CMBs, who were scanned at two different field strengths, with ground truth QSM reference calculated using multiple orientation scans. 7T MRI provided QSM images with lower noise than did 3T MRI. QSIP and VSHARP + iLSQR achieved the highest white matter homogeneity and vein contrast, with QSIP also providing the highest CMB contrast. Compared with ground truth COSMOS QSM images, overall good correlations between susceptibility values of dipole inversion algorithms and the COSMOS reference were observed in basal ganglia regions, with VSHARP + iLSQR achieving the susceptibility values most similar to COSMOS across all regions. This study can provide guidance for selecting the most appropriate QSM processing pipeline based on the application of interest and scanner field strength. 相似文献
77.
78.
Andrea Ferrari MD Daniel Orbach MD Michela Casanova MD Max M. van Noesel MD Pablo Berlanga MD Bernadette Brennan MD Nadege Corradini MD Reineke A. Schoot MD Gema L. Ramirez-Villar MD Lisa Lyngsie Hjalgrim MD Rita Alaggio MD Gabriela Guillen Burrieza MD Akmal Safwat MD Alison L. Cameron MD Rick R. van Rijn MD Veronique Minard-Colin MD Ilaria Zanetti BSc Gianni Bisogno MD Julia C. Chisholm MD Johannes H. M. Merks MD 《Cancer》2023,129(16):2542-2552
Background
Limited data exist on the clinical behavior of pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) with distant metastases at onset, and a clear standard of care has not yet been defined.Methods
This cohort study reports on pediatric adult-type metastatic NRSTS enrolled in two concurrent prospective European studies, i.e., the randomized BERNIE study and the single-arm MTS 2008 study developed by the European paediatric Soft tissue sarcoma Study Group. Treatment programs were originally designed for patients with metastatic rhabdomyosarcoma, i.e., nine courses of multidrug chemotherapy (with or without bevacizumab in the BERNIE study), followed by 12 cycles of maintenance therapy, whereas radiotherapy and/or surgery (on primary tumor and/or metastases) were delayed until after seven courses of chemotherapy had been administered.Results
The study included 61 patients <21 years old treated from July 2008 to December 2016. The lung was the site of metastases in 75% of the cases. All patients received multi-agent chemotherapy, 44% had local therapy to primary tumor, and 18% had treatment of metastases. Median time to progression/relapse was 6 months. A high rate of tumor progression was observed during the initial part of the chemotherapy program. With a median follow-up of 41.5 months (range, 2–111 months), 3-year event-free survival and overall survival were 15.4% (95% confidence interval [CI], 7.6–25.7) and 34.9% (95% CI, 22.7–47.5), respectively. There were no statistically significant differences in outcome depending on the type of treatment administered.Conclusions
The study confirmed the overall poor outcome for patients with metastatic NRSTS, whose treatment remains a challenge.Plain Language Summary
- Pediatric non-rhabdomyosarcoma soft tissue sarcomas form a heterogeneous group of rare tumors.
- Although recent international studies have defined the standard of care for patients with localized disease, limited data are available on the clinical behavior of patients with distant metastases.
- This study on 61 metastatic cases treated on two prospective European protocols confirms that the chances of survival of such patients are often dismal and a standard treatment is still lacking.
79.
80.