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   19673篇
  免费   1614篇
  国内免费   45篇
耳鼻咽喉   210篇
儿科学   614篇
妇产科学   490篇
基础医学   2572篇
口腔科学   688篇
临床医学   2508篇
内科学   3681篇
皮肤病学   295篇
神经病学   1965篇
特种医学   394篇
外科学   2332篇
综合类   306篇
一般理论   20篇
预防医学   2585篇
眼科学   396篇
药学   1148篇
  1篇
中国医学   22篇
肿瘤学   1105篇
  2023年   79篇
  2022年   75篇
  2021年   333篇
  2020年   231篇
  2019年   337篇
  2018年   464篇
  2017年   303篇
  2016年   350篇
  2015年   402篇
  2014年   582篇
  2013年   956篇
  2012年   1298篇
  2011年   1354篇
  2010年   766篇
  2009年   724篇
  2008年   1257篇
  2007年   1337篇
  2006年   1256篇
  2005年   1206篇
  2004年   1180篇
  2003年   1030篇
  2002年   1054篇
  2001年   150篇
  2000年   124篇
  1999年   136篇
  1998年   176篇
  1997年   148篇
  1996年   115篇
  1995年   130篇
  1994年   123篇
  1993年   140篇
  1992年   97篇
  1991年   84篇
  1990年   69篇
  1989年   101篇
  1988年   104篇
  1987年   68篇
  1985年   99篇
  1984年   130篇
  1983年   133篇
  1982年   165篇
  1981年   162篇
  1980年   174篇
  1979年   107篇
  1978年   128篇
  1977年   110篇
  1976年   103篇
  1975年   80篇
  1973年   79篇
  1972年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.

Background

Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism.

Methods

A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status.

Results

Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (–0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (–1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients.

Conclusion

Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile.  相似文献   
6.
Although histopathology is the time‐honored gold standard diagnostic measure in dermatology, several factors may detract from an accurate microscopic diagnosis. Limiting factors include: human error, suboptimal biopsy‐site selection or biopsy technique, and inherent restrictions of vertical tissue sectioning that lead to incomplete microscopic evaluation of the lesion. Reflectance confocal microscopy (RCM) is a non‐invasive imaging tool that allows for the cellular‐level examination of the lesion, at a horizontal plane, which may complement the subsequent vertical histopathological tissue examination. Herein, we report a case series whereby prebiopsy RCM examination enhanced the accuracy of histopathological diagnosis or allowed for a critical appraisal of initial histopathological misdiagnosis.  相似文献   
7.
Attenuation coefficient estimation has the potential to be a useful tool for placental tissue characterization. A current challenge is the presence of inhomogeneities in biological tissue that result in a large variance in the attenuation coefficient estimate (ACE), restricting its clinical utility. In this work, we propose a new Attenuation Estimation Region Of Interest (AEROI) selection method for computing the ACE based on the (i) envelope signal-to-noise ratio deviation and (ii) coefficient of variation of the transmit pulse bandwidth. The method was first validated on a tissue-mimicking phantom, for which an 18%–21% reduction in the standard deviation of ACE and a 14%–24% reduction in the ACE error, expressed as a percentage of reported ACE, were obtained. A study on 59 post-delivery clinically normal placentas was then performed. The proposed AEROI selection method reduced the intra-subject standard deviation of ACE from 0.72 to 0.39 dB/cm/MHz. The measured ACE of 59 placentas was 0.77 ± 0.37 dB/cm/MHz, which establishes a baseline for future studies on placental tissue characterization.  相似文献   
8.
BackgroundThe efficacy of ticagrelor in the long-term post–ST-segment elevation myocardial infarction (STEMI) treated with fibrinolytic therapy remains uncertain.ObjectivesThe purpose of this study was to evaluate the efficacy of ticagrelor when compared with clopidogrel in STEMI patients treated with fibrinolytic therapy.MethodsThis international, multicenter, randomized, open-label with blinded endpoint adjudication trial enrolled 3,799 patients (age <75 years) with STEMI receiving fibrinolytic therapy. Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300- to 600-mg loading dose, 75 mg daily thereafter). The key outcomes were cardiovascular mortality, myocardial infarction, or stroke, and the same composite outcome with the addition of severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events at 12 months.ResultsThe combined outcome of cardiovascular mortality, myocardial infarction, or stroke occurred in 129 of 1,913 patients (6.7%) receiving ticagrelor and in 137 of 1,886 patients (7.3%) receiving clopidogrel (hazard ratio: 0.93; 95% confidence interval: 0.73 to 1.18; p = 0.53). The composite of cardiovascular mortality, myocardial infarction, stroke, severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events occurred in 153 of 1,913 patients (8.0%) treated with ticagrelor and in 171 of 1,886 patients (9.1%) receiving clopidogrel (hazard ratio: 0.88; 95% confidence interval: 0.71 to 1.09; p = 0.25). The rates of major, fatal, and intracranial bleeding were similar between the ticagrelor and clopidogrel groups.ConclusionAmong patients age <75 years with STEMI, administration of ticagrelor after fibrinolytic therapy did not significantly reduce the frequency of cardiovascular events when compared with clopidogrel. (Ticagrelor in Patients With ST Elevation Myocardial Infarction Treated With Pharmacological Thrombolysis [TREAT]; NCT02298088)  相似文献   
9.
10.
Kaposiform lymphangiomatosis (KLA) is a rare, life‐threatening congenital lymphatic malformation. Diagnosis is often delayed due to complex indistinct symptoms. Blood angiopoietin‐2 (ANG2) levels are elevated in KLA and may be useful as a biomarker to monitor disease status. We report a 7‐year‐old male child with easy bruising, inguinal swelling, and consumptive coagulopathy, diagnosed with KLA. A multimodal treatment regimen of prednisone, sirolimus, vincristine, and adjunctive zoledronate was used. Plasma ANG2 levels were highly elevated at diagnosis but decreased during treatment. The patient showed significant clinical improvement over a 38‐month period and normalization of ANG2 levels correlated with resolution of the coagulopathy.  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