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   65931篇
  免费   4647篇
  国内免费   396篇
耳鼻咽喉   904篇
儿科学   1385篇
妇产科学   1040篇
基础医学   10092篇
口腔科学   1475篇
临床医学   6491篇
内科学   13545篇
皮肤病学   1814篇
神经病学   5974篇
特种医学   3024篇
外国民族医学   11篇
外科学   8671篇
综合类   575篇
现状与发展   3篇
一般理论   38篇
预防医学   4195篇
眼科学   1226篇
药学   5283篇
中国医学   519篇
肿瘤学   4709篇
  2023年   518篇
  2022年   1233篇
  2021年   2058篇
  2020年   1258篇
  2019年   1698篇
  2018年   2014篇
  2017年   1603篇
  2016年   2063篇
  2015年   2513篇
  2014年   2953篇
  2013年   3582篇
  2012年   5382篇
  2011年   5282篇
  2010年   3096篇
  2009年   2497篇
  2008年   3784篇
  2007年   3735篇
  2006年   3422篇
  2005年   3145篇
  2004年   2802篇
  2003年   2394篇
  2002年   2139篇
  2001年   1014篇
  2000年   999篇
  1999年   866篇
  1998年   480篇
  1997年   380篇
  1996年   339篇
  1995年   293篇
  1994年   261篇
  1993年   211篇
  1992年   430篇
  1991年   426篇
  1990年   414篇
  1989年   338篇
  1988年   335篇
  1987年   349篇
  1986年   361篇
  1985年   330篇
  1984年   264篇
  1983年   213篇
  1982年   150篇
  1979年   289篇
  1978年   197篇
  1977年   164篇
  1975年   171篇
  1974年   157篇
  1973年   161篇
  1972年   158篇
  1971年   168篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
91.
Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.  相似文献   
92.
93.
94.
Integrated surveillance of infectious multi-source diseases using a combination of epidemiology, ecology, genetics and evolution can provide a valuable risk-based approach for the control of important human pathogens. This includes a better understanding of transmission routes and the impact of human activities on the emergence of zoonoses. Until recently New Zealand had extraordinarily high and increasing rates of notified human campylobacteriosis, and our limited understanding of the source of these infections was hindering efforts to control this disease. Genetic and epidemiological modeling of a 3-year dataset comprising multilocus sequence typed isolates from human clinical cases, coupled with concurrent data on food and environmental sources, enabled us to estimate the relative importance of different sources of human disease. Our studies provided evidence that poultry was the leading cause of human campylobacteriosis in New Zealand, causing an estimated 58–76% of cases with widely varying contributions by individual poultry suppliers. These findings influenced national policy and, after the implementation of poultry industry-specific interventions, a dramatic decline in human notified cases was observed in 2008. The comparative-modeling and molecular sentinel surveillance approach proposed in this study provides new opportunities for the management of zoonotic diseases.  相似文献   
95.
The X‐linked McLeod neuroacanthocytosis syndrome strongly resembles Huntington's disease and has been reported in various countries world‐wide. Herein, we report two Chilean brothers with predominant psychiatric features at disease onset including schizophrenia‐like psychosis and obsessive compulsive disorder. Molecular genetic analysis revealed a small deletion in the XK gene (938‐942delCTCTA), which has been already described in a North American patient of Anglo‐Saxon descent and a Japanese family, presenting with seizures, muscle atrophy or chorea yet absence of psychiatric features. These findings argue against a founder effect and indicate a profound phenotypic variability associated with the 938‐942delCTCTA deletion. Our report supports the inclusion of McLeod syndrome in the differential diagnosis of Huntington's disease as well as acute psychosis in male subjects. © 2007 Movement Disorder Society  相似文献   
96.
Laparoscopic transhiatal surgery of the esophagus.   总被引:4,自引:0,他引:4  
OBJECTIVE: Esophagectomy is an operation with high morbidity and mortality. Its adoption as a minimally invasive operation worldwide has been slow, but the potential benefits of reducing the trauma of surgery need to be considered. Our 30-month experience with transhiatal esophagectomy in a district general hospital is presented herein. METHODS: Patients were considered for surgery after radiological staging had excluded inoperable disease. Laparoscopic staging was initially performed. Patients with tumors of the esophagus and high-grade dysplasia in a Barrett's esophagus were included. RESULTS: Twenty-nine patients were referred for consideration for resectional surgery. Nine underwent outpatient laparoscopy only. Twenty patients (age range, 34 to 78, 15 males:5 females) underwent resectional surgery. Seventeen transhiatal resections were completed, 2 were converted to open procedures, and 1 transhiatal resection of a benign tumor was performed. Median time of surgery was 415 minutes (range, 320 to 480) and blood loss was 300 mL (range, 200 to 350). The median length of post-operative ventilation and critical care stay were 1 (range, 1 to 4) and 4 (range, 2 to 8) days. Median duration of hospitalization was 17 days (range, 10 to 28). Thirty-day mortality was 0; 1 patient who was converted to an open procedure died after a cerebrovascular event on day 34. CONCLUSION: A zero mortality rate for laparoscopic resection and a low-morbidity rate compare well with morbidity and mortality in reported series using this method and open surgery. Laparoscopic transhiatal esophagectomy is an advanced, complex procedure that can be performed safely in a district general hospital setting.  相似文献   
97.
OBJECTIVE: We performed a prospective, randomized clinical trial to compare the usefulness of the minute ventilation test (MVT) with clinical judgement in predicting readiness for extubation in preterm newborns with respiratory distress syndrome requiring surfactant therapy and mechanical ventilation. STUDY DESIGN: A total of 42 preterm infants with respiratory distress syndrome were randomized when they reached preselected ventilator settings. The primary outcome measure was the time from study entry to extubation, provided the infant remained extubated for at least 24 hours. RESULTS: Infants evaluated by the MVT were extubated in a significantly shorter period of time (mean of 8 hours) than those evaluated clinically (mean of 36 hours). The extubation failure rate was similar in the two groups. CONCLUSION: The MVT is an easily performed objective measure that can be used to predict readiness for extubation in preterm infants. In this study, it significantly shortened the time for extubation and was not associated with a higher rate of reintubation.  相似文献   
98.
99.
100.
OBJECTIVE: Tacrolimus has been shown to provide superior immunosuppression in various solid organ transplant settings. The purpose of our study was to compare the survival of porcine lung allografts after induction with either cyclosporine A (CsA) or tacrolimus. METHODS: Single lung transplantation from MHC mismatched donors was performed in 10 minipigs. Immunosuppression included 1.5 mg/kg per day methylprednisolone and 1.0 mg/kg per day azathioprine. CsA (n=5) was adjusted to trough levels of 300-500 ng/ml, tacrolimus (n=5) was adjusted to 16-26 ng/ml. All immunosuppressive drugs were discontinued on postoperative day (POD) 28. Allograft survival was monitored by sequential chest radiographs, bronchoscopy and transbronchial biopsy histology. Peripheral blood leukocytes were scanned for donor chimerism and CD3, CD4, CD8 and CD25 expression. RESULTS: The animals survived a 4-week course of immunosuppression without radiological or histological signs of rejection on POD 28. Median allograft survival in CsA-treated animals was 55+/-15 days and all animals rejected their grafts within 42 days after withdrawal of immunosuppression. In tacrolimus-treated animals, median survival was 152+/-65 days with the longest survivor being electively sacrificed on POD 390 (P=0.0064). The degree of donor leukocyte chimerism and the frequency of CD4+CD25+ T-cells were higher in the tacrolimus group, however, these differences were not statistically significant. CONCLUSION: The results of our study show that primary immunosuppression with tacrolimus is superior to cyclosporine after pulmonary allotransplantation in a large animal model.  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