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   4762篇
  免费   305篇
  国内免费   2篇
耳鼻咽喉   113篇
儿科学   74篇
妇产科学   70篇
基础医学   615篇
口腔科学   60篇
临床医学   475篇
内科学   1084篇
皮肤病学   181篇
神经病学   514篇
特种医学   163篇
外科学   505篇
综合类   22篇
一般理论   1篇
预防医学   359篇
眼科学   76篇
药学   339篇
中国医学   3篇
肿瘤学   415篇
  2023年   33篇
  2022年   42篇
  2021年   141篇
  2020年   102篇
  2019年   146篇
  2018年   137篇
  2017年   103篇
  2016年   116篇
  2015年   120篇
  2014年   189篇
  2013年   243篇
  2012年   347篇
  2011年   344篇
  2010年   192篇
  2009年   151篇
  2008年   269篇
  2007年   270篇
  2006年   270篇
  2005年   253篇
  2004年   220篇
  2003年   175篇
  2002年   159篇
  2001年   78篇
  2000年   74篇
  1999年   68篇
  1998年   33篇
  1997年   33篇
  1996年   36篇
  1995年   48篇
  1994年   24篇
  1993年   27篇
  1992年   49篇
  1991年   52篇
  1990年   40篇
  1989年   43篇
  1988年   46篇
  1987年   33篇
  1986年   22篇
  1985年   27篇
  1984年   33篇
  1983年   28篇
  1982年   34篇
  1981年   20篇
  1979年   24篇
  1978年   15篇
  1977年   16篇
  1975年   15篇
  1974年   20篇
  1972年   18篇
  1970年   12篇
排序方式: 共有5069条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.

Assessment of size and growth are key radiological factors in low-grade gliomas (LGGs), both for prognostication and treatment evaluation, but the reliability of LGG-segmentation is scarcely studied. With a diffuse and invasive growth pattern, usually without contrast enhancement, these tumors can be difficult to delineate. The aim of this study was to investigate the intra-observer variability in LGG-segmentation for a radiologist without prior segmentation experience. Pre-operative 3D FLAIR images of 23 LGGs were segmented three times in the software 3D Slicer. Tumor volumes were calculated, together with the absolute and relative difference between the segmentations. To quantify the intra-rater variability, we used the Jaccard coefficient comparing both two (J2) and three (J3) segmentations as well as the Hausdorff Distance (HD). The variability measured with J2 improved significantly between the two last segmentations compared to the two first, going from 0.87 to 0.90 (p?=?0.04). Between the last two segmentations, larger tumors showed a tendency towards smaller relative volume difference (p?=?0.07), while tumors with well-defined borders had significantly less variability measured with both J2 (p?=?0.04) and HD (p?<?0.01). We found no significant relationship between variability and histological sub-types or Apparent Diffusion Coefficients (ADC). We found that the intra-rater variability can be considerable in serial LGG-segmentation, but the variability seems to decrease with experience and higher grade of border conspicuity. Our findings highlight that some criteria defining tumor borders and progression in 3D volumetric segmentation is needed, if moving from 2D to 3D assessment of size and growth of LGGs.

  相似文献   
75.
Osteoarthritis of the hands is very common, particularly in elderly people. Little is known though, is the subset of erosive osteoarthritis (EOA), which predicts a poorer prognosis and causes much more discomfort. Even less known is the fact that this subset can evolve into spontaneous ankylosis. We describe eight women (average age 62.6, range 54–74 years) with EOA and spontaneous ankylosis of the proximal interphalangeal (PIP) and/or distal interphalangeal (DIP) joints. In total, 21 PIP joints (0–7 per patient) were found with EOA and nine PIP joints (0–3 per patient) with ankylosis. In one patient, ankylosis of the PIP was already seen at the first presentation. In the other cases, it took an average of 77.4 months (range 34–119) for EOA to develop into ankylosis of the PIP. For DIP joints, the numbers were 17 joints (1–4 per patient) with EOA and three joints (0–1 per patient) with ankylosis, respectively. In one patient, ankylosis of the DIP was already seen at the first presentation. Ankylosis was found significantly more often on the left hand (n?=?10) compared to the right hand (n?=?2; p?<?0.0005), while all the patients were right handed. No difference in handedness was found for the occurrence of EOA. Although rare, PIP or DIP joint with EOA can—over the course of several painful years—develop into a spontaneous pain-free ankylosis. Ankylosis was more commonly found in the left hand than in the right hand, probably due right handedness.  相似文献   
76.
77.
Illicit drug profiling performed by forensic laboratories assists law enforcement agencies through providing information about chemical and/or physical characteristics of seized specimens. In this article, a model was developed for the comparison of seized cocaine based on retrospective analysis of data generated from ultrahigh performance liquid chromatography with time-of-flight mass spectrometry (UHPLC-TOF-MS) comprehensive drug screening. A nontargeted approach to discover target compounds was employed, which generated 53 potential markers using data from cocaine positive samples. Twelve marker compounds were selected for the development of the final profiling model. The selection included a mixture of commonly used cocaine profiling targets and other cocaine-related compounds. Combinations of pretreatments and comparison metrics were assessed using receiver operating characteristic curves to determine the combination with the best discrimination between linked and unlinked populations. Using data from 382 linked and 34,519 unlinked distances, a classification model was developed using a combination of the standardization and normalization transformations with Canberra distance, resulting in a linked cut-off with a 0.5% false positive rate. The present study demonstrates the applicability of retrospectively developing a cocaine profiling model using data generated from UHPLC-TOF-MS nontargeted drug screening without pre-existing information about cocaine impurities. The developed workflow was not specific to cocaine and thus could potentially be applied to any seized drug in which there are both sufficient data and impurities present.  相似文献   
78.
79.
Summary To demonstrate the wide variety of clinical syndromes associated with the lupus anticoagulant (LAC), we report the case histories of three young females with arterial thrombosis in whom LAC was demonstrated. Two patients had a diagnosis of systemic lupus erythematosus and mixed connective tissue disease respectively; the other patient had no signs of underlying auto-immune disease. Arterial thrombotic events in young females should arouse suspicion of the presence of LAC although its pathophysiological significance is not established.  相似文献   
80.
Previous research has documented that people with diabetes report lower psychological well-being than do people with no reported disease. In recent years, new treatment regimens for diabetes have been introduced, including improved insulin and tablet treatment, easier blood sugar tests, and transfer of responsibility from doctor to patient. Have these improved methods for controlling diabetes resulted in enhanced psychological well-being for this group of patients? In this paper, we analyze changes in psychological well-being between 1984-1986 and 1995-1997 among diabetic patients. On these two occasions, the entire adult population of one county in Norway was invited to a health screening (the Nord-Tr?ndelag Health Studies, HUNT 1 and HUNT 2). Participants reached 77,224 and 65,599 persons, respectively (90.7% in HUNT 1 and 71.0% in HUNT 2). The participants responded to questionnaires, including questions on several diseases and impairments, as well as self-assessed health and psychological well-being. People with diabetes reported significantly lower well-being than people with no reported diabetes in HUNT 1 as well as in HUNT 2. However, the relationship between diabetes and well-being was significantly weaker in HUNT 2 than in HUNT 1. Self-reported Subjective health, the feeling of being strong and fit, the use of Tranquilizers, and Psychological distress had improved between the two surveys, for people with diabetes compared to people with no reported diabetes. Other outcome variables - Calmness, Cheerfulness, and Life satisfaction - were only weakly related to diabetes, and the relationship did not change significantly from HUNT 1 to HUNT 2.  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