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   3043篇
  免费   183篇
  国内免费   18篇
耳鼻咽喉   31篇
儿科学   90篇
妇产科学   66篇
基础医学   291篇
口腔科学   55篇
临床医学   295篇
内科学   634篇
皮肤病学   46篇
神经病学   145篇
特种医学   105篇
外科学   517篇
综合类   52篇
一般理论   9篇
预防医学   322篇
眼科学   114篇
药学   315篇
中国医学   26篇
肿瘤学   131篇
  2024年   8篇
  2023年   33篇
  2022年   107篇
  2021年   116篇
  2020年   88篇
  2019年   128篇
  2018年   145篇
  2017年   109篇
  2016年   114篇
  2015年   116篇
  2014年   157篇
  2013年   222篇
  2012年   265篇
  2011年   282篇
  2010年   147篇
  2009年   132篇
  2008年   183篇
  2007年   163篇
  2006年   153篇
  2005年   122篇
  2004年   99篇
  2003年   90篇
  2002年   64篇
  2001年   29篇
  2000年   24篇
  1999年   13篇
  1998年   14篇
  1997年   13篇
  1996年   10篇
  1995年   6篇
  1994年   7篇
  1993年   2篇
  1992年   7篇
  1991年   6篇
  1990年   8篇
  1989年   12篇
  1988年   5篇
  1987年   9篇
  1986年   2篇
  1985年   3篇
  1984年   4篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1975年   6篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1968年   1篇
  1963年   1篇
排序方式: 共有3244条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
Lasers in Medical Science - Low-level laser has been indicated to have the capability to facilitate the differentiation of the osteoclastic and osteoblastic cells which are responsible for the bone...  相似文献   
66.
BACKGROUND: The epidemiology and natural history of hepatitis C virus (HCV) infection in the UK are uncertain. Previous reports are from small or selected populations such as blood donors or tertiary referral centres. AIMS: To study the epidemiology and natural history of HCV infection. METHODS: Prospective study incorporating five centres within the Trent region. Patients were managed and followed up according to a commonly agreed protocol. SUBJECTS: A total of 1128 HCV positive patients. Patients with haemophilia, human immunodeficiency virus, and chronic renal failure were excluded. RESULTS: Between September 1991 and December 1998, 2546 anti-HCV positive patients were identified of whom 1128 (44%) were enrolled in the cohort. A risk factor(s) for infection was identified in 93.4% of patients who completed the questionnaire; 81% of patients were HCV RNA positive. A total of 397 initial liver biopsies were scored by a single pathologist. These showed a correlation between high alcohol intake and fibrosis score. Multivariate analysis showed fibrosis to be associated with age over 40, past evidence of hepatitis B virus infection, and higher necroinflammatory grade but not with sex, viral genotype, maximum known alcohol intake, estimated duration of infection, or mode of transmission. Twelve (7.8%) of 153 patients who received interferon therapy had sustained serum virus clearance. Sixty six patients have died during the follow up period, 31 with a liver related cause of death. This represents a considerable excess over the expected death rate for a cohort of this age and sex distribution. CONCLUSIONS: HCV infection is an emerging health problem in the Trent region. Identifying risk factors for infection and disease severity will enhance understanding and facilitate improved intervention. An excess mortality in infected individuals is already evident in this unselected cohort.  相似文献   
67.
In search of novel genes expressed in metastatic prostate cancer, we subtracted cDNA isolated from benign prostatic hypertrophic tissue from cDNA isolated from a prostate cancer xenograft model that mimics advanced disease. One novel gene that is highly expressed in advanced prostate cancer encodes a 339-amino acid protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This structure suggests a potential function as a channel or transporter protein. This gene, named STEAP for six-transmembrane epithelial antigen of the prostate, is expressed predominantly in human prostate tissue and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. Immunohistochemical analysis of clinical specimens demonstrates significant STEAP expression at the cell-cell junctions of the secretory epithelium of prostate and prostate cancer cells. Little to no staining was detected at the plasma membranes of normal, nonprostate human tissues, except for bladder tissue, which expressed low levels of STEAP at the cell membrane. Protein analysis located STEAP at the cell surface of prostate-cancer cell lines. Our results support STEAP as a cell-surface tumor-antigen target for prostate cancer therapy and diagnostic imaging.  相似文献   
68.
Oxidative stress and antioxidant status in type 1 diabetes mellitus   总被引:2,自引:0,他引:2  
OBJECTIVES: To test the hypothesis that type 1 diabetes is associated with increased oxidative stress and/or antioxidant status by investigating concentrations of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) in urine and plasma and malondialdehyde (MDA) in plasma as indicators of lipid peroxidation in vivo, and antioxidant status in diabetic subjects compared with healthy control subjects. DESIGN AND SUBJECTS: Thirty-eight subjects with type 1 diabetes mellitus and 41 healthy age- and sex-matched control subjects were included in the study. Blood and urine samples were obtained and analysed for 8-iso-PGF2alpha with a newly developed radioimmunoassay, as well as for MDA, total antioxidant capacity (TAOC) and serum tocopherol levels. RESULTS: None of the variables of lipid peroxidation showed any significant difference between the two groups. Similarly, there were no significant correlations between the levels of 8-iso-PGF2alpha or MDA, and degree of glycemic control (HbA1c). Total antioxidant capacity in plasma was 16% lower amongst the subjects with type 1 diabetes than in the control group (P < 0.0005). Lipid corrected levels of alpha-tocopherol in serum were significantly increased in type 1 diabetic subjects (P < 0.05), as were gamma-tocopherol levels (P < 0.005). CONCLUSIONS: In spite of lower total antioxidant defence, our results do not support the oxidative stress hypothesis for type 1 diabetes mellitus. The higher tocopherol levels suggest that no vitamin E supplementation is necessary for subjects with type 1 diabetes mellitus.  相似文献   
69.

Background

Surgical myectomy reverses heart failure symptoms in the vast majority of obstructive hypertrophic cardiomyopathy patients. However, a small subgroup fails to experience sustained postoperative improvement despite relief of obstruction. Clinical profile of such patients has not been well defined.

Methods

Consecutive obstructive hypertrophic cardiomyopathy patients undergoing myectomy at Tufts Medical Center for drug-refractory New York Heart Association III/IV heart failure symptoms, 2004 to 2017, were followed postoperatively for 2.5 ± 2.8 years and assessed for outcome.

Results

Of the 503 patients, there were 4 postoperative deaths (0.8%); 480 patients (96%) had sustained improvement to New York Heart Association classes I or II (responders), but 19 (3.8%) developed advanced symptoms (classes III or IV) in the absence of obstruction (nonresponders). Compared with responders, nonresponders were younger (40 ± 13 vs 53 ± 14 years; P < .001) and had greater septal thickness (25 ± 9 vs 20 ± 4 mm; P < .001). Massive hypertrophy (≥30 mm) was 5-fold more common in nonresponders (P < .01). Seven nonresponders developed systolic dysfunction (ejection fraction 20%-47%), 2 days to 6.1 years postoperatively. Four nonresponders underwent heart transplant 3.4 to 9.2 years after myectomy, and 2 others have been listed.

Conclusions

Surgical myectomy is highly effective at reversing heart failure symptoms in the vast majority of patients with obstructive hypertrophic cardiomyopathy. However, a small minority experience persistent functional limitation despite surgical relief of outflow obstruction. Predictors of adverse postoperative course were substantial/massive septal thickness and youthful age. Patients who failed to respond symptomatically to myectomy were considered for advanced heart failure treatment, including heart transplantation.  相似文献   
70.
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