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   676篇
  免费   50篇
  国内免费   3篇
儿科学   6篇
基础医学   72篇
口腔科学   23篇
临床医学   43篇
内科学   172篇
皮肤病学   8篇
神经病学   91篇
特种医学   22篇
外科学   125篇
综合类   1篇
预防医学   12篇
眼科学   15篇
药学   75篇
中国医学   1篇
肿瘤学   63篇
  2023年   5篇
  2022年   8篇
  2021年   8篇
  2020年   8篇
  2019年   8篇
  2018年   10篇
  2017年   8篇
  2016年   14篇
  2015年   17篇
  2014年   13篇
  2013年   11篇
  2012年   32篇
  2011年   47篇
  2010年   12篇
  2009年   19篇
  2008年   26篇
  2007年   35篇
  2006年   27篇
  2005年   27篇
  2004年   27篇
  2003年   29篇
  2002年   22篇
  2001年   19篇
  2000年   19篇
  1999年   19篇
  1998年   13篇
  1997年   8篇
  1995年   6篇
  1994年   6篇
  1993年   6篇
  1992年   25篇
  1991年   15篇
  1990年   20篇
  1989年   10篇
  1988年   9篇
  1987年   12篇
  1986年   15篇
  1985年   17篇
  1984年   14篇
  1983年   14篇
  1982年   5篇
  1981年   6篇
  1980年   8篇
  1979年   9篇
  1978年   6篇
  1977年   4篇
  1975年   4篇
  1974年   5篇
  1973年   4篇
  1967年   4篇
排序方式: 共有729条查询结果,搜索用时 15 毫秒
71.
72.
Red-crowned cranes (Grus japonensis) are native to eastern Hokkaido (island population), in contrast to the mainland, which migrates between the Amur River basin and eastern China-Korea peninsula. During the 1990s we found that Red-crowned cranes in Hokkaido were highly contaminated with mercury: however, the source was unknown. We investigated the time trend of mercury contamination in Red-crowned cranes. Total mercury levels in the livers and kidneys from cranes dead in the 2000s were lower than those dead in the 1990s. Feather is a major pathway of mercury excretion for many bird species and is used as an indicator of blood mercury level during feather growth. As internal organs from the specimens collected before 1988 were not available, we analyzed the flight feather shavings from stuffed Red-crowned cranes dead in 1959-1987 and found that the mercury level of feathers from cranes dead in the 1960s and 1970s was not more than those from the cranes dead in the 2000s. These results suggest that mercury contamination in Red-crowned cranes in Hokkaido decreased temporally during the 1990s-2000s. This indicates the possible occurrence of some mercury pollution in Red-crowned cranes' habitat in this region in the 1990s or before.  相似文献   
73.
74.
Aim: Nonalcoholic fatty liver disease (NAFLD) represents a growing health concern due to its rapidly increasing prevalence worldwide. Nonalcoholic steatohepatitis (NASH) is a progressing form of NAFLD, and recently many studies have reported that it could eventually develop into hepatocellular carcinoma (HCC). We previously reported that 6‐month‐old male galectin‐3 knockout (gal3?/?) mice developed clinicopathological features similar to those of NAFLD in humans. Our aim was to investigate the changes in liver histology in gal3?/? mice by long‐term observation. Methods: We initially investigated three 15‐month‐old gal3?/? mice, of which two developed multiple liver nodules with dysplastic changes. Then, we histopathologically examined the liver specimens of the 15‐, 20‐ and 25‐month‐old gal3?/? mice and attempted to evaluate the liver morphology by contrast enhanced computed tomography (CT) before sacrifice. Results: At the age of 15 months or later, gal3?/? mice developed liver nodules with varying degrees of architectural and nuclear atypia based on mild to moderate delicate zone 3 fibrosis. In addition, we successfully confirmed the presence of some of the liver nodules by CT. We report herein that gal3?/? mice develop dysplastic liver nodules and HCC. Conclusions: We believe that it would be interesting to use this murine model to investigate liver carcinogenesis based on a natural history of NAFLD. Furthermore, CT scanning might be a useful tool for longitudinal evaluation of morphological changes in vivo.  相似文献   
75.
76.
The aim of the present study was to evaluate exercise limiting factors using cardiopulmonary exercise testing (CPET) in patients with idiopathic pulmonary fibrosis (IPF), and to investigate whether these parameters are related to survival after CPET. We evaluated 41 patients with IPF (mean 68.2 years, 27 male) who performed CPET. The exercise capacity in patients with IPF was limited more strongly by gas exchange and/or ventilatory impairments, compared with cardiac impairment. Using univariate analysis, the severity of exercise-induced hypoxemia (EIH) evaluated by deltaPaO2/deltaVO2 (PaO2-slope), oxygen uptake at maximum exercise, oxygen pulse at maximum exercise, ventilatory equivalent for carbon dioxide at maximum exercise and age were significantly related to the survival rate. Interestingly, the PaO2-slope was most closely correlated with the survival rate using multiple analysis with a stepwise evaluation. Nevertheless, PaO2 at rest and at maximum exercise were not factors influencing survival. In patients with IPF, CPET can simultaneously evaluate the ability of both the cardiovascular and respiratory systems, and should be available so that parameters can be derived to make the necessary prognostic estimations, with the most useful parameter being the degree of EIH as represented by the PaO2-slope.  相似文献   
77.
OBJECTIVES: To examine the direct detection of rifampicin (RFP)-resistant Mycobacterium tuberculosis in sputum by Line Probe Assay (LiPA). MATERIALS AND METHODS: We collected 130 sputa and analyzed both by LiPA and the Amplicor M.tuberculosis assay. For culture-positive samples, RFP resistance testing was performed and compared with the results by LiPA. RESULTS: Eighty two out of 84 M. tuberculosis samples were detected by LiPA and all of 10 Mycobacteria other than M. tuberculosis (MOTT) samples and 36 negative samples were negative by LiPA. The detection rate is same as Amplicor. For culture-positive samples, LiPA showed mutation pattern for all of 22 RFP-resistant strains and wild type pattern for 19 of 20 RFP-sensitive strains. The one remaining showed mixed pattern of wild type and mutation pattern. CONCLUSION: The use of LiPA for sputum coould enable early detection of RFP-resistant tuberculosis and seems to be useful for the control of tuberculosis.  相似文献   
78.
Percutaneous vertebroplasty (PVP) is an interventional treatment for painful vertebral compression fractures caused by osteoporosis and malignant diseases such as multiple myeloma and metastatic bone tumors. We present the first case of PVP performed on a man in his thirties with vertebral compression fractures secondary to acute lymphoblastic leukemia. PVP at T11 and L1 levels resulted in a marked improvement in refractory pain although he developed delayed pyogenic spondylitis two months after the intervention. This case suggests that PVP could be one of the useful therapeutic procedures for intractable back pain associated with vertebral compression fractures in acute lymphoblastic leukemia if we are extremely vigilant for the risk of spondylitis.  相似文献   
79.
Direct-acting antivirals (DAAs) are either part of the current standard of care or are in advanced clinical development for the treatment of patients chronically infected with hepatitis C virus (HCV) genotype 1, but concern exists with respect to the patients who fail these regimens with emergent drug-resistant variants. In the present study, ultradeep sequencing was performed to analyze resistance to daclatasvir (DCV), which is a highly selective nonstructural protein 5A (NS5A) inhibitor. Eight patients with HCV genotype 1b, who were either treatment naive or prior nonresponders to pegylated interferon plus ribavirin (Rebetol; Schering-Plough) (PEG-IFN/RBV) therapy, were treated with DCV combined with PEG-IFN alpha-2b (Pegintron; Schering-Plough, Kenilworth, NJ) and RBV. To identify the cause of viral breakthrough, the preexistence and emergence of DCV-resistant variants at NS5A amino acids were analyzed by ultradeep sequencing. Sustained virological response (SVR) was achieved in 6 of 8 patients (75%), with viral breakthrough occurring in the other 2 patients (25%). DCV-resistant variant Y93H preexisted as a minor population at higher frequencies (0.1% to 0.5%) in patients who achieved SVR. In patients with viral breakthrough, DCV-resistant variant mixtures emerged at NS5A-31 over time that persisted posttreatment with Y93H. Although enrichment of DCV-resistant variants was detected, the preexistence of a minor population of the variant did not appear to be associated with virologic response in patients treated with DCV/PEG-IFN/RBV. Ultradeep sequencing results shed light on the complexity of DCV-resistant quasispecies emerging over time, suggesting that multiple resistance pathways are possible within a patient who does not rapidly respond to a DCV-containing regimen. (This study has been registered at ClinicalTrials.gov under registration no. NCT01016912.)  相似文献   
80.
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