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   273732篇
  免费   39116篇
  国内免费   3517篇
耳鼻咽喉   6940篇
儿科学   7224篇
妇产科学   4275篇
基础医学   23492篇
口腔科学   4611篇
临床医学   37924篇
内科学   68820篇
皮肤病学   11372篇
神经病学   24785篇
特种医学   13578篇
外科学   56822篇
综合类   768篇
现状与发展   75篇
一般理论   29篇
预防医学   13562篇
眼科学   6553篇
药学   12526篇
中国医学   1513篇
肿瘤学   21496篇
  2024年   556篇
  2023年   5298篇
  2022年   2752篇
  2021年   7496篇
  2020年   8008篇
  2019年   5126篇
  2018年   10917篇
  2017年   10166篇
  2016年   12138篇
  2015年   13659篇
  2014年   21600篇
  2013年   22866篇
  2012年   16788篇
  2011年   16342篇
  2010年   16394篇
  2009年   19322篇
  2008年   13270篇
  2007年   11188篇
  2006年   12951篇
  2005年   9776篇
  2004年   8226篇
  2003年   6553篇
  2002年   5982篇
  2001年   6807篇
  2000年   5785篇
  1999年   5314篇
  1998年   4517篇
  1997年   4122篇
  1996年   3857篇
  1995年   3654篇
  1994年   2316篇
  1993年   1893篇
  1992年   2122篇
  1991年   2099篇
  1990年   1697篇
  1989年   1728篇
  1988年   1476篇
  1987年   1319篇
  1986年   1216篇
  1985年   1079篇
  1984年   812篇
  1983年   712篇
  1982年   649篇
  1981年   574篇
  1980年   490篇
  1979年   529篇
  1978年   494篇
  1977年   516篇
  1975年   398篇
  1972年   410篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
73.
74.
ObjectiveTo compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS).Materials and MethodsThe Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements.ResultsLumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm3; 95% confidence interval [CI], 4.9–24.3 mm3); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, −0.7 mm3; 95% CI, −9.1–7.7 mm3). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm2; 95% CI, 0.89–1.25 mm2) but not in the larger lumen area group (mean of difference, −0.07 mm2; 95% CI, −0.22–0.08 mm2). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm2; 95% CI, 0.27–0.65 mm2) than in that of IVUS and SATM (1.53 mm2; 95% CI, 1.27–1.79 mm2).ConclusionSATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM.  相似文献   
75.
76.
Hypertrophic lichen planus (HLP) is a T‐cell‐mediated process typically presenting with hypertrophic or verrucous plaques on the lower limbs. We report the case of a 24‐year‐old woman with a history of HLP since age 3 years presenting with rapid malignant transformation of one lesion into a large squamous cell carcinoma (SCC). Subsequent examination revealed progressive, widespread metastatic involvement, and the patient ultimately died from her disease. SCC associated with HLP is rare, with a review of the literature revealing fewer than 50 cases. This case highlights the need to be aware of suspicious changes in HLP and to educate patients as to when to be reevaluated.  相似文献   
77.
78.
TL1A is a TNF‐like cytokine which has been shown to co‐stimulate TH1 and TH17 responses during chronic inflammation. The expression of this novel cytokine has been investigated in inflammatory disorders like rheumatoid arthritis and inflammatory bowel disease, but little is known about expression and induction in psoriasis. Indeed, the pathogenesis in psoriasis is still not fully understood and it is speculated that cytokines other than TNF‐α are important in subsets of patients. Also, for patients with severe disease that are treated with systemic anti‐TNF‐α blockade, novel candidates to be used as disease and response biomarkers are of high interest. Here, we demonstrate TL1A expression in biopsies from psoriatic lesions. Also, we investigated spontaneous and induced TL1A secretion from PBMCs and blood levels from a cohort of psoriasis patients. Here, increased spontaneous secretion from PBMCs was observed as compared to healthy controls and a small subset of patients had highly elevated TL1A in the blood. Interestingly, activation of PBMCs with various cytokines showed a decreased sensitivity for TL1A activation in psoriasis patients compared to healthy controls.TL1A levels in blood and biopsies could not be correlated with disease activity with this patient cohort. Thus, additional large‐scale studies are warranted to investigate TL1A as a biomarker.  相似文献   
79.
80.
Breast elastography has been available for more than 15 years but is not widely incorporated into clinical practice. Many publications report extremely high accuracy for various breast elastographic techniques. However, results in the literature are extremely variable. This variability is most likely due to variations in technique, a relatively steep learning curve, and variability in methods between vendors. This article describes our protocol for performing breast elastography using both strain elastography and shear wave elastography, which produces high sensitivity and specificity. Additionally, we will describe the most commonly known false-positive and false-negative lesions as well as how to detect them.  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