首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   15259篇
  免费   1418篇
  国内免费   67篇
耳鼻咽喉   204篇
儿科学   368篇
妇产科学   230篇
基础医学   2014篇
口腔科学   220篇
临床医学   1555篇
内科学   3319篇
皮肤病学   378篇
神经病学   952篇
特种医学   612篇
外科学   2578篇
综合类   108篇
现状与发展   1篇
一般理论   4篇
预防医学   1273篇
眼科学   510篇
药学   1148篇
中国医学   83篇
肿瘤学   1187篇
  2023年   155篇
  2022年   125篇
  2021年   704篇
  2020年   459篇
  2019年   558篇
  2018年   661篇
  2017年   436篇
  2016年   510篇
  2015年   532篇
  2014年   669篇
  2013年   724篇
  2012年   1148篇
  2011年   1105篇
  2010年   658篇
  2009年   528篇
  2008年   912篇
  2007年   898篇
  2006年   761篇
  2005年   711篇
  2004年   627篇
  2003年   553篇
  2002年   509篇
  2001年   497篇
  2000年   452篇
  1999年   365篇
  1998年   106篇
  1997年   87篇
  1996年   81篇
  1995年   75篇
  1994年   68篇
  1993年   60篇
  1992年   155篇
  1991年   107篇
  1990年   121篇
  1989年   112篇
  1988年   95篇
  1987年   80篇
  1986年   68篇
  1985年   63篇
  1984年   51篇
  1983年   34篇
  1982年   19篇
  1981年   11篇
  1980年   17篇
  1979年   16篇
  1978年   7篇
  1977年   10篇
  1976年   8篇
  1975年   7篇
  1974年   5篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
1.
2.
3.
Quantitative ultrasound (QUS) was used to classify rabbits that were induced to have liver disease by placing them on a fatty diet for a defined duration and/or periodically injecting them with CCl4. The ground truth of the liver state was based on lipid liver percents estimated via the Folch assay and hydroxyproline concentration to quantify fibrosis. Rabbits were scanned ultrasonically in vivo using a SonixOne scanner and an L9-4/38 linear array. Liver fat percentage was classified based on the ultrasonic backscattered radiofrequency (RF) signals from the livers using either QUS or a 1-D convolutional neural network (CNN). Use of QUS parameters with linear regression and canonical correlation analysis demonstrated that the QUS parameters could differentiate between livers with lipid levels above or below 5%. However, the QUS parameters were not sensitive to fibrosis. The CNN was implemented by analyzing raw RF ultrasound signals without using separate reference data. The CNN outputs the classification of liver as either above or below a threshold of 5% fat level in the liver. The CNN outperformed the classification utilizing the QUS parameters combined with a support vector machine in differentiating between low and high lipid liver levels (i.e., accuracies of 74% versus 59% on the testing data). Therefore, although the CNN did not provide a physical interpretation of the tissue properties (e.g., attenuation of the medium or scatterer properties) the CNN had much higher accuracy in predicting fatty liver state and did not require an external reference scan.  相似文献   
4.
5.
ObjectiveTo evaluate differences in postoperative pain control and opioids requirement in thoracic surgical patients following implementation of an Enhanced Recovery after Thoracic Surgery protocol with a comprehensive postoperative pain management strategy.Material and MethodsA retrospective analysis of a prospectively maintained database of patients undergoing pulmonary resections by robotic thoracoscopy or thoracotomy from January 1, 2017, to January 31, 2019, was conducted. Multimodal pain management strategy (opioid-sparing analgesics, infiltration of liposomal bupivacaine to intercostal spaces and surgical sites, and elimination of thoracic epidural analgesia use in thoracotomy patients) was implemented as part of Enhanced Recovery after Thoracic Surgery on February 1, 2018. Outcome metrics including patient-reported pain levels, in-hospital and postdischarge opioids use, postoperative complications, and length of stay were compared before and after protocol implementation.ResultsIn total, 310 robotic thoracoscopy and 62 thoracotomy patients met the inclusion criteria. This pain management strategy was associated with significant reduction of postoperative pain in both groups with an overall reduction of postoperative opioids requirement. Median in-hospital opioids use (morphine milligram equivalent per day) was reduced from 30 to 18.36 (P = .009) for the robotic thoracoscopy group and slightly increased from 15.48 to 21.0 (P = .27) in the thoracotomy group. More importantly, median postdischarge opioids prescribed (total morphine milligram equivalent) was significantly reduced from 480.0 to 150.0 (P < .001) and 887.5 to 150.0 (P < .001) for the thoracoscopy and thoracotomy groups, respectively. Similar short-term perioperative outcomes were observed in both groups before and following protocol implementation.ConclusionsImplementation of Enhanced Recovery after Thoracic Surgery allows safe elimination of epidural use, better pain control, and less postoperative opioids use, especially a drastic reduction of postdischarge opioid need, without adversely affecting outcomes.  相似文献   
6.

Background

With the worldwide spread of antibiotic resistance, delivering antibiotic susceptibility test (AST) results in a timely manner represents a major challenge. In cases of sepsis, rapid AST may facilitate early optimization of empiric antibiotic therapy. Disc diffusion is a well-standardized AST method, however 16 to 24?h are required to achieve an overall AST profile according to antimicrobial societies.

Methods

In this prospective pilot study, we evaluated the performance of Mueller-Hinton-Rapid-SIR (MHR-SIR) agar after 6–8?h of incubation in comparison with standard MH agar after 16?h of incubation directly on positive blood cultures caused by Enterobacteriaceae and Staphylococcus aureus from routine clinical microbiology.A total of 133 positive blood samples including 110 Enterobacteriaceae (83%) and 23 Staphylococcus aureus (17%) were tested in parallel by two direct AST methods, each using EUCAST breakpoints. For each combination bacterium and antibiotic, we compared the categorical agreement and the correlation between the diameters obtained by MHR-SIR and by standard MH.

Results

Our results showed 97.7% categorical agreement for Enterobacteriaceae, with 1.4% minor errors, 0.4% major errors and 0.5% very major errors. For S. aureus, we observed 97.8% categorical agreement, 1.9% minor errors, 0.3% major errors and no very major errors.

Conclusion

Our results showed excellent categorical agreement and correlations between diameters for MHR-SIR and standard MH methods. MHRSIR can predict the result of overall AST profile within 6–8?h with reliable results. AST is obtained on the same day the blood culture becomes positive, with a very moderate cost.  相似文献   
7.

Purpose

Although current Delphi Consensus guidelines do not recommend a specific definition of biochemical recurrence after partial gland therapy, these guidelines acknowledge that serial prostate-specific antigen (PSA) tests remain the best marker for monitoring disease after treatment. The purpose of this study was to determine whether PSA velocity at failure per the Phoenix (nadir + 2 ng/mL) definition is associated with metastasis and prostate cancer-specific mortality (PCSM) in a cohort of patients who experienced PSA failure after partial gland therapy.

Methods

Between 1997 and 2007, 285 patients with favorable risk prostate cancer underwent partial prostate brachytherapy to the peripheral zone. PSA velocity was calculated for 94 patients who experienced PSA failure per the Phoenix (nadir + 2) definition. Fine and Gray competing risks regression was performed to determine whether PSA velocity and other clinical factors were associated with metastasis and PCSM.

Results

The median time to PSA failure was 4.2 years (interquartile range: 2.2, 7.9), and the median followup time after PSA failure was 6.5 years (3.5–9.7). Seventeen patients developed metastases, and five experienced PCSM. On multivariate analysis, PSA velocity ≥3.0 ng/mL/year (adjusted hazard ratio 5.97; [2.57, 13.90]; p < 0.001) and PSA nadir (adjusted hazard ratio 0.39; [0.24, 0.64]; p < 0.001) were significantly associated with metastasis. PSA velocity ≥3.0 ng/mL/year was also associated with PCSM (HR 15.3; [1.8, 128.0]; p = 0.012) on univariate analysis.

Conclusions

Rapid PSA velocity at PSA failure after partial gland treatment may be prognostic for long-term outcomes.  相似文献   
8.
9.
10.
There is increasing evidence showing that clinicians employ different management strategies in their use of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this meta-analysis, we investigated the differences in diagnosis frequency, resection rate (RR), and risk of malignancy (ROM) between Western (ie, American and European) and Asian cytopathology practices. We searched PubMed and Web of Science from January 2010 to January 2019. Proportion and 95% CIs were calculated using a random-effect model. We used independent sample t tests to compare frequencies, RR, and ROM between Western and Asian practices. We analyzed a total of 38 studies with 145,066 fine-needle aspirations. Compared with Asian practice, Western series had a significantly lower ROM in most of TBSRTC categories, whereas the RR was not statistically different. Focusing on indeterminate nodules, the RR in Western series was significantly higher (51.3% vs 37.6%; P = .048), whereas the ROM was significantly lower (25.4% vs 41.9%; P = .002) compared with those in Asian series. The addition of Asian cohorts increased ROM for most of diagnostic categories compared with the original TBSRTC. In conclusion, this study demonstrates a difference in Western and Asian thyroid cytology practice, especially regarding the indeterminate categories. Lower RR and higher ROM suggest that Asian clinicians adopt a more conservative approach, whereas immediate diagnostic surgery is favored in Western practice for indeterminate nodules. The addition of Asian series into a meta-analysis of TBSRTC altered ROM for several categories, which should be considered in future revisions of TBSRTC.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号