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   1620499篇
  免费   104545篇
  国内免费   2313篇
耳鼻咽喉   21726篇
儿科学   54297篇
妇产科学   44440篇
基础医学   228172篇
口腔科学   41362篇
临床医学   133978篇
内科学   319707篇
皮肤病学   32287篇
神经病学   130998篇
特种医学   63766篇
外国民族医学   457篇
外科学   247015篇
综合类   29482篇
现状与发展   1篇
一般理论   358篇
预防医学   126086篇
眼科学   35455篇
药学   119768篇
  1篇
中国医学   3646篇
肿瘤学   94355篇
  2019年   11433篇
  2018年   38155篇
  2017年   28733篇
  2016年   31893篇
  2015年   17146篇
  2014年   21578篇
  2013年   32946篇
  2012年   53776篇
  2011年   68786篇
  2010年   45085篇
  2009年   35468篇
  2008年   64400篇
  2007年   70131篇
  2006年   50576篇
  2005年   51277篇
  2004年   50182篇
  2003年   49016篇
  2002年   46213篇
  2001年   62712篇
  2000年   64320篇
  1999年   54523篇
  1998年   14347篇
  1997年   12805篇
  1996年   12874篇
  1995年   12860篇
  1994年   12226篇
  1992年   43297篇
  1991年   42524篇
  1990年   42003篇
  1989年   40569篇
  1988年   37841篇
  1987年   36909篇
  1986年   35177篇
  1985年   33496篇
  1984年   24907篇
  1983年   21653篇
  1982年   12863篇
  1981年   11292篇
  1979年   23498篇
  1978年   16452篇
  1977年   14251篇
  1976年   13431篇
  1975年   14776篇
  1974年   17405篇
  1973年   16804篇
  1972年   15992篇
  1971年   14914篇
  1970年   13879篇
  1969年   13429篇
  1968年   12571篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
53.
This meta-analysis focuses on the accuracy of upgrading to clinically significant prostate cancer (PCa) by multiparametric magnetic resonance imaging-targeted biopsy (MRI-TB) versus systematic biopsy (SB). We searched the Medline, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Scopus, and Literatura Latino Americana em Ciências da Saúde databases through January 2020 for comparative, retrospective/prospective, paired-cohort, and randomized clinical trials with paired comparisons. The population consisted of patients with low-risk PCa in active surveillance with at least 1 index lesion on imaging. We evaluated the quality of evidence by using the Quality Assessment of Diagnostic Accuracy Studies-2 score. Group comparisons considered the differences between the area under the curve summary receiver operating characteristic curve in a 2-tailed method. We also compared the positive predictive value of the best single method (MRI-TB or SB) and the referral study test (combined biopsy, a combination of MRI-TB and SB). The meta-analysis included 6 studies enrolling 741 patients. The pooled sensitivity for the 2 groups was 0.79 (95% confidence interval, 0.74-0.83; I2 = 75%) and 0.67 (95% confidence interval, 0.63-0.74; I2 = 55.4%), respectively. The area under the curve for the MRI-TB and SB groups were 0.99 and 0.92 (P < .001), respectively. The positive predictive value for the MRI-TB and combined biopsy groups were similar. The accumulated evidence suggests better results for MRI-TB compared with SB. Therefore, use of MRI-TB alone may be preferable in patients in active surveillance harboring low-risk PCa.  相似文献   
54.
55.
56.
57.
ObjectiveTo assess the evolution of cost per patient/year and the cost per patient/year/drug in patients with rheumatoid arthritis (RA) receiving biological treatments. To analyze and quantify the factors influencing this evolution, such as the optimization of the biological drugs, the use of biosimilars, and official discounts and discounts obtained after negotiated procedures. In addition, to assess specific clinical parameters of disease activity in these patients.MethodsRetrospective, observational study conducted in a Spanish tertiary hospital. Adult patients diagnosed with RA under treatment from 2009 to 2017 were included.Results320, 270 and 389 patients were included in 2009, 2013 and 2017, respectively. The patient/year cost decreased from 10,789€ in 2009, 7491€ in 2013 to 7116€ in 2017. In 2017, due to the established competition, discounts of 14% and 29.5% were achieved on etanercept and its biosimilar; 11.5%, 17.8%, 17.9%, 17.3% on adalimumab, certolizumab, golimumab and tocilizumab IV respectively, and 24.6% and 43.1% on infliximab and its biosimilar. The percentage of patients optimized in 2017 was 35.2%. The annual saving in 2017 was 1,288,535€ (830,000€ due to dose optimization and/or administration regimens, 249,666€ corresponding to 7.5% of the official discount and 208,868€ after negotiated procedures).ConclusionThe annual cost per patient in RA decreased considerably due to different factors, such as discounts on the purchase of drugs due to official discounts and negotiated procedures, together with the optimization of therapies, the latter being the factor that contributed most to this decrease.  相似文献   
58.
There have been a number of investigations of the efficacy and safety of etanercept. This study was performed to obtain long-term drug survival data (ie, time to drug discontinuation) for etanercept, and the reasons for its discontinuation. The study population consisted of patients with psoriatic arthritis and psoriasis followed up by our clinic, registered in the Turkish Psoriasis Registry (PSR-TR) and treated with etanercept for at least 4 weeks between January 1, 2005, and January 31, 2020. The efficacy of etanercept was evaluated in terms of the Psoriasis Area and Severity Index (PASI) 75, PASI 90 and PASI 100 response rates at 12, 24, 36, and 48 weeks, and annually thereafter. The behaviors of the patients with respect to the use of etanercept, and the outcomes of those who continued to use it during the COVID-19 pandemic, were also investigated.  相似文献   
59.
IntroductionOrgan-based tube current modulation (OBTCM) is designed for anterior dose reduction in Computed Tomography (CT). The purpose was to assess dose reduction capability in chest CT using three organ dose modulation systems at different kVp settings. Furthermore, noise, diagnostic image quality and tumour detection was assessed.MethodsA Lungman phantom was scanned with and without OBTCM at 80–135/140 kVp using three CT scanners; Canon Aquillion Prime, GE Revolution CT and Siemens Somatom Flash. Thermo-luminescent dosimeters were attached to the phantom surface and all scans were repeated five times. Image noise was measured in three ROIs at the level of the carina. Three observers visually scored the images using a fivestep scale. A Wilcoxon Signed-Rank test was used for statistical analysis of differences.ResultsUsing the GE revolution CT scanner, dose reductions between 1.10 mSv (12%) and 1.56 mSv (24%) (p < 0.01) were found in the anterior segment and no differences posteriorly and laterally. Total dose reductions between 0.64 (8%) and 0.91 mSv (13%) were found across kVp levels (p < 0.00001). Maximum noise increase with OBTCM was 0.8 HU. With the Canon system, anterior dose reductions of 6–10% and total dose reduction of 0.74–0.76 mSv across kVp levels (p < 0.001) were found with a maximum noise increase of 1.1 HU. For the Siemens system, dose increased by 22–51% anteriorly; except at 100 kVp where no dose difference was found. Noise decreased by 1 to 1.5 HU.ConclusionOrgan based tube current modulation is capable of anterior and total dose reduction with minimal loss of image quality in vendors that do not increase posterior dose.Implications for practiceThis research highlights the importance of being familiar with dose reduction technologies.  相似文献   
60.
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