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   177727篇
  免费   1104篇
  国内免费   15篇
耳鼻咽喉   1180篇
儿科学   6695篇
妇产科学   3027篇
基础医学   16947篇
口腔科学   1564篇
临床医学   12553篇
内科学   31615篇
皮肤病学   724篇
神经病学   16545篇
特种医学   8926篇
外科学   29059篇
综合类   2316篇
预防医学   18205篇
眼科学   2740篇
药学   9613篇
中国医学   627篇
肿瘤学   16510篇
  2023年   23篇
  2022年   46篇
  2021年   130篇
  2020年   70篇
  2019年   118篇
  2018年   22002篇
  2017年   17421篇
  2016年   19554篇
  2015年   966篇
  2014年   879篇
  2013年   852篇
  2012年   7111篇
  2011年   21136篇
  2010年   18884篇
  2009年   11590篇
  2008年   19622篇
  2007年   21816篇
  2006年   703篇
  2005年   2268篇
  2004年   3473篇
  2003年   4451篇
  2002年   2588篇
  2001年   335篇
  2000年   493篇
  1999年   243篇
  1998年   221篇
  1997年   218篇
  1996年   113篇
  1995年   116篇
  1994年   106篇
  1993年   73篇
  1992年   60篇
  1991年   117篇
  1990年   149篇
  1989年   89篇
  1988年   75篇
  1987年   56篇
  1986年   40篇
  1985年   36篇
  1984年   24篇
  1983年   25篇
  1982年   27篇
  1980年   45篇
  1939年   20篇
  1938年   60篇
  1937年   25篇
  1935年   22篇
  1934年   30篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
Prostate cancer is a prevalent public health problem worldwide. While imaging has played a major role in this disease, there still remain many challenges and opportunities. Positron emission tomography with various physiologically based radiotracers is fundamentally suited to interrogate this biologically and clinically heterogeneous disease along the course of its natural history. In this article, I review briefly the published evidence for the use of positron emission tomography with 18F-fluorodeoxyglucose, 11C-acetate, and 18F- or 11C-choline in the imaging evaluation of prostate cancer. Although the focus of the article will be on these radiotracers given the accumulated experience with them, but I will also comment on the outlook for the use of other emerging PET radiotracers such as those targeted to the prostate-specific membrane antigen and the amino acid metabolism pathway. It is anticipated that PET will play major role in the evaluation of prostate cancer in the current evidence-based medicine environment. There will also be exciting novel prospects for the use of therapeutic-diagnostic (theransotic) pairs in the management of patients with prostate cancer.  相似文献   
942.
943.
Incarceration of a rectal prolapse is an unusual entity that represents a surgical emergency. Even more rarely, it becomes strangulated, requiring emergency surgery. When surgery becomes inevitable, the choice of procedure varies. A 57-year-old man who presented with strangulated rectal prolapse is described. The patient underwent emergency perineal proctosigmoidectomy, the Altemeier operation, combined with diverting loop sigmoid colostomy. The postoperative course was uneventful. After a 6-month follow-up, there was no recurrence, but the patient continued with fecal incontinence. This case underlines the importance of the Altemeier procedure as treatment in the patient with a strangulated prolapsed rectal segment.  相似文献   
944.
945.
946.
Haemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory condition with impairment of cytotoxic T-cells and natural killer cells. Causes in infants are mostly hereditary immune defects as well as various infectious triggering factors, amongst these cytomegalovirus (CMV). Vertical CMV transmission may occur in utero, during birth, and by breast feeding. Usually, a CMV infection transmitted via breast milk is symptomatic only in very immature preterm infants. We report on a late preterm infant born after 35 + 5 weeks of gestation with a birth weight of 1840 g, being admitted to our intensive care unit at the age of 9 weeks with acute enteritis and severe dehydration. After a prolonged recovery, the infant developed a sepsis-like condition with hyperpyrexia, hepatosplenomegaly, and pancytopenia. Combination with high ferritin levels (2809 μg/l), hypertriglyceridaemia (481 mg/dl), elevated soluble IL-2 receptor (sCD25, 9120 U/ml), and reduced perforin expression allowed diagnosis of HLH, caused by an acute CMV infection. Since connatal CMV infection had been ruled out earlier, we report the rare case of secondary HLH triggered by a postnatally acquired symptomatic CMV infection in an immunocompetent infant, most likely transmitted via breast milk. The infant was successfully treated with ganciclovir without need for immunosuppressive therapy.  相似文献   
947.
Here, we show that AU-1, spirostanol saponin isolated from Agavaceae plants, causes a transient increase in cyclin-dependent kinase inhibitor (CDKI) p21/Cip1 through the upregulation of miRNAs, miR-34 and miR-21. AU-1 stimulated p21/Cip1 expression without exerting cytotoxicity against different types of carcinoma cell lines. In renal adenocarcinoma ACHN cells, AU-1 transiently elevated the expression level of p21/Cip1 protein without marked increases in p21/Cip1 mRNA levels. Rapid and transient increases in miR-34 and miR-21, both of which are known to upregulate p21/Cip1, were observed in AU-1-treated cells. Inhibitor for miR-34 and for miR-21 significantly blocked the AU-1-caused increase in p21/Cip1, indicating that elevation of p21/Cip1 protein by AU-1 is dependent on these microRNAs. We further clarified that NAD-dependent deacetylase SIRT1, a direct target of miR-34, is decreased by the treatment with AU-1. Furthermore, we found that SIRT1-knockdown increases p21/Cip1 protein levels in an miR-21-dependent manner. On the other hand, ectopic expression of p21/Cip1 resulted in the lowered expression of miR-34 and miR-21, suggesting that reciprocal regulation exists between p21/Cip1 and these miRNAs. We propose that the following feedback network composed of miR-34/SIRT1/miR-21/p21 is triggered by the treatment with AU-1: in cells treated with AU-1, transient elevation of miR-34 leads to the downregulation of SIRT1, thereby miR-21 is freed from SIRT1-dependent suppression. Then, elevated miR-21 upregulates p21/Cip1 protein, followed by the suppression of miR-34 expression.  相似文献   
948.
Radon is the second leading cause of lung cancer among smokers and the leading cause among nonsmokers. The Centers for Disease Control and Prevention’s National Comprehensive Cancer Control Program (NCCCP) funds every state, seven tribes, seven territories and the District of Columbia to develop formal cancer plans that focus efforts in cancer control. A 2010 review of cancer plans identified radon-related activities in 27 (42%) plans. Since then, 37 coalitions have updated their plans with new or revised cancer control objectives. There has also been recent efforts to increase awareness about radon among cancer coalitions. This study assesses NCCCP grantees current radon activities and changes since the 2010 review. We reviewed all 65 NCCCP grantee cancer plans created from 2005 to 2015 for radon related search terms and categorized plans by radon activities. The program’s most recent annual progress report to CDC was also reviewed. We then compared the results from the updated plans with the findings from the 2010 review to assess changes in radon activities among cancer coalitions. Changes in state radon laws between 2010 and 2015 were also assessed. While a number of cancer plans have added or expanded radon-specific activities since 2010, approximately one-third of NCCCP grantees still do not include radon in their cancer plans. Cancer programs can consider addressing radon through partnership with existing radon control programs to further reduce the risk of lung cancer, especially among non-smokers.  相似文献   
949.
950.
Diaphragm weakness is highly prevalent in critically ill patients. It may exist prior to ICU admission and may precipitate the need for mechanical ventilation but it also frequently develops during the ICU stay. Several risk factors for diaphragm weakness have been identified; among them sepsis and mechanical ventilation play central roles. We employ the term critical illness-associated diaphragm weakness to refer to the collective effects of all mechanisms of diaphragm injury and weakness occurring in critically ill patients. Critical illness-associated diaphragm weakness is consistently associated with poor outcomes including increased ICU mortality, difficult weaning, and prolonged duration of mechanical ventilation. Bedside techniques for assessing the respiratory muscles promise to improve detection of diaphragm weakness and enable preventive or curative strategies. Inspiratory muscle training and pharmacological interventions may improve respiratory muscle function but data on clinical outcomes remain limited.  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