全文获取类型
| 收费全文 | 3476495篇 |
| 免费 | 228963篇 |
| 国内免费 | 5991篇 |
专业分类
| 耳鼻咽喉 | 47268篇 |
| 儿科学 | 112680篇 |
| 妇产科学 | 94010篇 |
| 基础医学 | 499281篇 |
| 口腔科学 | 98429篇 |
| 临床医学 | 314370篇 |
| 内科学 | 665988篇 |
| 皮肤病学 | 77098篇 |
| 神经病学 | 273181篇 |
| 特种医学 | 129277篇 |
| 外国民族医学 | 693篇 |
| 外科学 | 518742篇 |
| 综合类 | 76042篇 |
| 现状与发展 | 14篇 |
| 一般理论 | 1255篇 |
| 预防医学 | 267760篇 |
| 眼科学 | 82892篇 |
| 药学 | 255249篇 |
| 89篇 | |
| 中国医学 | 7554篇 |
| 肿瘤学 | 189577篇 |
出版年
| 2021年 | 27494篇 |
| 2019年 | 28813篇 |
| 2018年 | 39191篇 |
| 2017年 | 29607篇 |
| 2016年 | 33058篇 |
| 2015年 | 37208篇 |
| 2014年 | 52427篇 |
| 2013年 | 78207篇 |
| 2012年 | 107879篇 |
| 2011年 | 114348篇 |
| 2010年 | 68230篇 |
| 2009年 | 64007篇 |
| 2008年 | 106782篇 |
| 2007年 | 113786篇 |
| 2006年 | 115051篇 |
| 2005年 | 111040篇 |
| 2004年 | 106802篇 |
| 2003年 | 102387篇 |
| 2002年 | 98839篇 |
| 2001年 | 163010篇 |
| 2000年 | 167349篇 |
| 1999年 | 140354篇 |
| 1998年 | 39864篇 |
| 1997年 | 34858篇 |
| 1996年 | 35046篇 |
| 1995年 | 33251篇 |
| 1994年 | 30574篇 |
| 1993年 | 28584篇 |
| 1992年 | 108242篇 |
| 1991年 | 105204篇 |
| 1990年 | 101938篇 |
| 1989年 | 98357篇 |
| 1988年 | 90196篇 |
| 1987年 | 88287篇 |
| 1986年 | 83050篇 |
| 1985年 | 79483篇 |
| 1984年 | 59010篇 |
| 1983年 | 50285篇 |
| 1982年 | 29364篇 |
| 1979年 | 53685篇 |
| 1978年 | 37853篇 |
| 1977年 | 31788篇 |
| 1976年 | 30146篇 |
| 1975年 | 32055篇 |
| 1974年 | 38828篇 |
| 1973年 | 37184篇 |
| 1972年 | 34708篇 |
| 1971年 | 32633篇 |
| 1970年 | 30278篇 |
| 1969年 | 28630篇 |
排序方式： 共有10000条查询结果，搜索用时 62 毫秒
91.
C. Ludes A. Labani F. Severac M.Y. Jeung P. Leyendecker C. Roy M. Ohana 《Diagnostic and interventional imaging》2019,100(2):85-93
Purpose
To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80 kVp and 135 kVp.Materials and methods
Fifty-one patients referred for unenhanced chest CT were prospectively included. There were 29 men and 22 women, with a mean age of 64.7 ± 11.6 (SD) years (range: 35–91 years) and a mean body mass index of 26.2 ± 6.3 (SD) (range: 17–54.9). All patients underwent two different ULD-CT protocols (80 kVp-40 mA and 135 kVp-10 mA). Image quality of both ULD-CT examinations using a 5-level scale as well as assessability of 6 predetermined lung parenchyma lesions were blindly evaluated by three radiologists and compared using a logistic regression model. Image noise of the two protocols was compared with Wilcoxon signed-rank test.Results
The mean dose-length product at 80 kVp and at 135 kVp were 14.7 ± 1.8 (SD) mGy.cm and 15.6 ± 1.9 (SD) mGy.cm, respectively (P < 0.001). Image noise was significantly lower at 135 kVp (58.9 ± 12.4) than at 80 kVp (74.7 ± 14.5) (P < 0.001). For all readers and for all examinations, the 135 kVp protocol yielded better image quality than 80 kVp protocol, with a mean qualitative score of 4.5 ± 0.7 versus 3.9 ± 0.8 (P < 0.001). The 135 kVp protocol was significantly more often of diagnostic quality than the 80 kvp protocol (92.3% versus 77.8%, respectively) (P < 0.001) and was less prone to image quality deterioration in obese patients. Parenchymal lesions were never better depicted on the 80 kVp protocol than with the 135 kVp protocol.Conclusion
Unenhanced chest ULD-CT should be acquired at a high kilovoltage and low current, such as 135 kVp-10 mA, over a low kilovoltage and high current protocol. 相似文献92.
P. Herent B. Schmauch P. Jehanno O. Dehaene C. Saillard C. Balleyguier J. Arfi-Rouche S. Jégou 《Diagnostic and interventional imaging》2019,100(4):219-225
Purpose
The purpose of this study was to assess the potential of a deep learning model to discriminate between benign and malignant breast lesions using magnetic resonance imaging (MRI) and characterize different histological subtypes of breast lesions.Materials and methods
We developed a deep learning model that simultaneously learns to detect lesions and characterize them. We created a lesion-characterization model based on a single two-dimensional T1-weighted fat suppressed MR image obtained after intravenous administration of a gadolinium chelate selected by radiologists. The data included 335 MR images from 335 patients, representing 17 different histological subtypes of breast lesions grouped into four categories (mammary gland, benign lesions, invasive ductal carcinoma and other malignant lesions). Algorithm performance was evaluated on an independent test set of 168 MR images using weighted sums of the area under the curve (AUC) scores.Results
We obtained a cross-validation score of 0.817 weighted average receiver operating characteristic (ROC)-AUC on the training set computed as the mean of three-shuffle three-fold cross-validation. Our model reached a weighted mean AUC of 0.816 on the independent challenge test set.Conclusion
This study shows good performance of a supervised-attention model with deep learning for breast MRI. This method should be validated on a larger and independent cohort. 相似文献93.
Background and purpose — No difference in outcome has been demonstrated comparing cemented taper-slip and composite beam designs in short-term randomised trials; we assessed outcome differences using a registry analysis.
Patients and methods — All cemented stems with > 100 implantations were identified in the National Joint Registry of England and Wales from April 1, 2003 to September 31, 2013 and categorised as taper-slip or composite beam. Survival analyses using Kaplan–Meier and Cox regression were performed.
Results — We identified 292,987 cemented arthroplasties, of which 16% (47,586) were composite beam stems, with taper-slip stems making up the remainder (n = 245,401). There was a statistically significant increased chance of revision in the composite beam group compared with the taper-slip group (1.7% vs 1.3%, p < 0.001) but statistically no significant differences of survival estimates (p = 0.06). When the 2 groups were segregated to delineate the most implanted model in each category, the differences became more profound with the most implanted taper-slip stem (Exeter V40) showing statistically and clinically significant superior 8-year survival: 97.9% compared with 97.6% for all other taper-slip; 97.5% for the most implanted composite beam (Charnley cemented stem); and 97.7% for all other composite beam.
Interpretation — There was an increased incidence of revision for composite beam stems. The most implanted taper-slip stem demonstrated significant survival advantage vs. all other stems. 相似文献
94.
V. Jenkins I. Solis-Trapala H. Payne M. Mason L. Fallowfield S. May L. Matthews S. Catt 《Clinical oncology (Royal College of Radiologists (Great Britain))》2019,31(2):99-107
Aims
Delaying progression, ameliorating symptoms and maintaining quality of life (QoL) are primary aims of treatment for metastatic castrate-resistant prostate cancer (mCRPC). Real-world rather than clinical trial data about symptoms and side-effects are sparse. In EXTREQOL, patients' QoL, pain and information needs were recorded during treatment.Material and methods
Men with mCRPC from 20 UK cancer centres starting various systemic mCRPC treatments completed QoL, pain and information needs questionnaires at baseline, 3 and 6 months.Results
In total, 132 patients were recruited. Overall QoL declined significantly by 6 months (Functional Assessment of Cancer Therapy-Prostate [FACT-P] mean = –3.89, 95% confidence interval –6.7 to –1.05, P = 0.007; Trial Outcome Index [TOI] analysis mean = –3.10, 95% confidence interval –5.34 to –0.83, P = 0.007). Those who came off novel therapy and remained on luteinising hormone-releasing hormone agonist therapy alone had worse scores than patients receiving concomitant chemotherapy (Prostate Concerns Subscale mean difference = –4.45, 95% confidence interval –7.06 to –1.83, P = 0.001; TOI mean difference = –5.62, 95% confidence interval –10.97 to –0.26, P = 0.040). At 3 and 6 months, men who reported pain at baseline improved (43%, 40%), but for others pain levels remained the same (45%, 42%) or worsened (13%, 18%). Information regarding supportive care was lacking throughout the period of time on the study.Conclusion
Most mCRPC treated patients experience reduced QoL and inadequate pain control. More help with pain management and better information provision regarding supportive care is warranted. 相似文献95.
K.A. Lee M.T.A. Sharabiani D. Tumino J. Wadsley V. Gill G. Gerrard R. Sindhu M.N. Gaze L. Moss K. Newbold 《Clinical oncology (Royal College of Radiologists (Great Britain))》2019,31(6):385-390
Aims
To obtain an overview of the management and outcomes of children aged 18 years or younger diagnosed with differentiated thyroid carcinoma of follicular cell origin across the UK, by collecting and analysing data from the limited number of centres treating these patients. This multicentre data might provide a more realistic perspective than single-institution series.Materials and methods
Six centres submitted data extracted from historical records on patients aged 18 years or younger, diagnosed between 1964 and 2017. The univariate and multivariable Cox proportional hazard model was used to identify potential predictors of progression-free survival, using national data as a control.Results
Data on 166 patients were available for analysis. Females (74%) were predominant, and the age ranged from 3 to 19 years at diagnosis, mean 14.1 years. Nodal metastases were present in 51%; 12% had distant metastases. After surgery, 95% received radioactive iodine (39% on more than one occasion) and 4% received external beam radiotherapy. With a median follow-up duration of 5 years, 69% are alive with no evidence of disease; 20% are alive with a raised thyroglobulin level as the only evidence of residual disease; 6% have residual structural disease detectable on imaging; 2% have died, from cerebral metastases.Conclusion
Despite most patients having advanced disease at presentation, outcomes are very good. A national prospective registry should allow systematic collection of good-quality data and may facilitate research to further improve outcomes. 相似文献96.
Edward J.A. Harris Steven Kao Brian McCaughan Takashi Nakano Nobuyuki Kondo Rebecca Hyland Anna K. Nowak Nicholas H. de Klerk Fraser J.H. Brims 《Journal of thoracic oncology》2019,14(2):288-293
Introduction
Malignant pleural mesothelioma (MPM) is an uncommon cancer with a poor prognosis and heterogeneous survival. Surgery for MPM is offered in some specialist centers to highly selected patients. A previously described classification and regression tree (CART) model stratified survival in unselected MPM patients using routinely collected clinical data. This study aimed to examine the performance of this CART model on a highly selected surgical population.Methods
Data were collected from subjects undergoing cytoreductive surgery for MPM from specialist centers in Hyõgo, Japan, and Sydney, Australia, between 1991 and 2016. The CART model was applied using the combination of clinical variables to stratify subjects into risk groups (1 through 4); survival characteristics were then compared.Results
Two hundred eighty-nine cases were included (205 from Australia, 84 from Japan). Overall median survival was 34.6 (interquartile range: 17.5–56.1) months; median age was 63.0 (interquartile range: 57.0–67.8) years, and 83.0% (n = 240) were male. There were no clinically meaningful differences between the two cohorts. Survival across the four risk groups was significantly different (p < 0.0001); the model stratified survival well with a Harrell's concordance statistic of 0.62 (95% confidence interval: 0.57–0.66) at 36 months. The group with the longest survival (median, 82.5 months) had: no weight loss, hemoglobin > 153 g/L and serum albumin > 43 g/L at time of referral to the surgical center.Conclusions
Using routinely available clinical variables, the CART model was able to stratify surgical patients into risk groups with statistically different survival characteristics with fair to good performance. Presence of weight loss, anemia, and low albumin should confer caution when considering surgical therapy for MPM. 相似文献97.
98.
Sabin J. Bozso Jeevan Nagendran Michael W.A. Chu Bob Kiaii Ismail El-Hamamsy Maral Ouzounian Jörg Kempfert Christoph Starck Michael C. Moon 《The Annals of thoracic surgery》2021,111(2):463-470
- Download : Download high-res image (134KB)
- Download : Download full-size image
99.
Sarah J. Schrauben Haochang Shou Xiaoming Zhang Amanda Hyre Anderson Joseph V. Bonventre Jing Chen Steven Coca Susan L. Furth Jason H. Greenberg Orlando M. Gutierrez Joachim H. Ix James P. Lash Chirag R. Parikh Casey M. Rebholz Venkata Sabbisetti Mark J. Sarnak Michael G. Shlipak Sushrut S. Waikar Paul L. Kimmel Ramachandran S. Vasan Harold I. Feldman Jeffrey R. Schelling 《Journal of the American Society of Nephrology : JASN》2021,32(1):115