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   536篇
  免费   63篇
耳鼻咽喉   7篇
儿科学   8篇
妇产科学   55篇
基础医学   62篇
口腔科学   2篇
临床医学   45篇
内科学   165篇
皮肤病学   3篇
神经病学   17篇
特种医学   42篇
外科学   73篇
综合类   22篇
预防医学   12篇
眼科学   13篇
药学   46篇
中国医学   6篇
肿瘤学   21篇
  2021年   12篇
  2020年   8篇
  2019年   26篇
  2018年   23篇
  2017年   22篇
  2016年   21篇
  2015年   25篇
  2014年   32篇
  2013年   45篇
  2012年   45篇
  2011年   36篇
  2010年   34篇
  2009年   30篇
  2008年   28篇
  2007年   36篇
  2006年   24篇
  2005年   13篇
  2004年   26篇
  2003年   16篇
  2002年   22篇
  2001年   11篇
  2000年   8篇
  1999年   5篇
  1998年   3篇
  1997年   5篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   3篇
  1983年   3篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有599条查询结果,搜索用时 171 毫秒
91.
92.
The central nervous system vasculature consists of a tightly sealed endothelium that forms the blood-brain barrier (BBB); these blood vessels are impermeable to large-molecular-size agents. The aim of this study was to determine the influence of prenatal ultrasound exposure on blood-brain barrier (BBB) integrity as measured by the permeation of Evans blue (EB) through the BBB during the postnatal development of the rat. Diagnostic levels of ultrasound (2.89 MHz, mechanical index = 1.1, acoustic output power = 70.5 mW) for 1 h and 2 h per day, for 9 consecutive days were used on Sprague-Dawley rats. Offspring were assessed postnatally on days 10, 17, 24 and 38. Our analysis of over 139 animals reveals that, when exposed to diagnostic levels of ultrasound during embryonic development, a statistically significant amount of EB extravasation into the cerebrum and cerebellum could be detected on postnatal day 10 but not later. In addition, small changes in pup body weight, cerebrum weight and cerebellum weight were observed after relatively prolonged ultrasound exposure on all postnatal days. Taken together, these results emphasize the need for further investigation of the effects of ultrasound exposure during the potentially vulnerable period of intense BBB development in the human fetus.  相似文献   
93.
Myocardial aging is characterized by left ventricular (LV) fibrosis leading to diastolic and systolic dysfunction. Studies have established the potent antifibrotic and antiproliferative properties of C-type natriuretic peptide (CNP); however, the relationship between circulating CNP, LV fibrosis, and associated changes in LV function with natural aging are undefined. Accordingly, we characterized the relationship of plasma CNP with LV fibrosis and function in 2-, 11-, and 20-month-old male Fischer rats. Further in vitro, we established the antiproliferative actions of CNP and the participation of the clearance receptor using adult human cardiac fibroblasts. Here we establish for the first time that a progressive decline in circulating CNP characterizes natural aging and is strongly associated with a reciprocal increase in LV fibrosis that precedes impairment of diastolic and systolic function. Additionally, we demonstrate in cultured adult human cardiac fibroblasts that the direct antiproliferative actions of high-dose CNP may involve a non-cGMP pathway via the clearance receptor. Together, these studies provide new insights into myocardial aging and the relationship to the antifibrotic and antiproliferative peptide CNP.  相似文献   
94.
95.
96.
97.
The positive rate of rickettsial antibodies of 107 rats in the Kinmen area by indirect immunofluorescent antibody (IFA) technique was 0% (0/107) in typhus fever, 38.3% (41/107) in scrub typhus and 66.4% (71/107) in spotted fever group; the positive rate (42.9%) of spotted fever group of 21 rats in Taiwan island also higher than scrub typhus (19.0). It suggests that spotted fever group patients may be present in our country but have not been discovered.  相似文献   
98.
Epigallocatechin gallate (EGCG) is a green tea polyphenol that presents anticancer activities in multiple cancer cells, but no available report was addressed for the underling molecular mechanism of cytotoxic impacts on drug‐resistant oral squamous cell carcinoma cells. In the present study, the inhibitory effects of EGCG were experienced on cisplatin‐resistant oral cancer CAR cells. EGCG inhibited cell viability in a time‐ and concentration‐dependent manner by a sulforhodamine B (SRB) assay. EGCG induced CAR cell apoptosis and autophagy by 4′,6‐diamidino‐2‐phenylindole (DAPI) dye, acridine orange (AO) staining and green fluorescent protein (GFP)‐tagged LC3B assay, respectively. EGCG also significantly enhanced caspase‐9 and caspase‐3 activities by caspase activity assay. EGCG markedly increased the protein levels of Bax, cleaved caspase‐9, cleaved caspase‐3, Atg5, Atg7, Atg12, Beclin‐1, and LC3B‐II, as well as significantly decreased the expression of Bcl‐2, phosphorylated AKT (Ser473) and phosphorylation of STAT3 on Tyr705 by western blotting in CAR cells. Importantly, the protein and gene expression of multidrug resistance 1 (MDR1) were dose‐dependently inhibited by EGCG. Overall, downregulation of MDR1 levels and alterations of AKT/STAT3 signaling contributed to EGCG‐induced apoptosis and autophagy in CAR cells. Based on these results, EGCG has the potential for therapeutic effect on oral cancer and may be useful for long‐term oral cancer prevention in the future. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 845–855, 2017.  相似文献   
99.
The concept of the heart as an endocrine organ has been attractive since the discovery of atrial natriuretic peptide. This review focuses on the second discovered natriuretic peptide from the heart - B-type natriuretic peptide (BNP), widely used as a tool in the diagnosis of heart failure (HF). Controversy remains regarding its use as a therapeutic agent in HF. This article places into perspective some of the debate and provides insights into the therapeutics of BNP and the importance of its second messenger 3'5' cyclic guanosine monophosphate, which also is the second messenger for nitric oxide and is modulated by renal phosphodiesterases.  相似文献   
100.
In an overcrowded emergency department (ED), trauma surgeons and emergency physicians need an accurate prognostic predictor for critical decision-making involving patients with severe trauma. We aimed to develope a machine learning-based early prognostic model based on admission features and initial ED management.We only recruited patients with severe trauma (defined as an injury severity score >15) as the study cohort and excluded children (defined as patients <16 years old) from a 4-years database (Chi-Mei Medical Center, from January 2015, to December 2018) recording the clinical features of all admitted trauma patients. We considered only patient features that could be determined within the first 2 hours after arrival to the ED. These variables included Glasgow Coma Scale (GCS) score; heart rate; respiratory rate; mean arterial pressure (MAP); prehospital cardiac arrest; abbreviated injury scales (AIS) of head and neck, thorax, and abdomen; and ED interventions (tracheal intubation/tracheostomy, blood product transfusion, thoracostomy, and cardiopulmonary resuscitation). The endpoint for prognostic analyses was mortality within 7 days of admission.We divided the study cohort into the early death group (149 patients who died within 7 days of admission) and non-early death group (2083 patients who survived at >7 days of admission). The extreme Gradient Boosting (XGBoost) machine learning model provided mortality prediction with higher accuracy (94.0%), higher sensitivity (98.0%), moderate specificity (54.8%), higher positive predict value (PPV) (95.4%), and moderate negative predictive value (NPV) (74.2%).We developed a machine learning-based prognostic model that showed high accuracy, high sensitivity, and high PPV for predicting the mortality of patients with severe trauma.  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