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   2440081篇
  免费   182280篇
  国内免费   3756篇
耳鼻咽喉   34026篇
儿科学   79437篇
妇产科学   68539篇
基础医学   346090篇
口腔科学   71629篇
临床医学   216446篇
内科学   468524篇
皮肤病学   53295篇
神经病学   192683篇
特种医学   97573篇
外国民族医学   665篇
外科学   370873篇
综合类   56677篇
现状与发展   4篇
一般理论   777篇
预防医学   182814篇
眼科学   56377篇
药学   188268篇
  10篇
中国医学   5189篇
肿瘤学   136221篇
  2018年   23641篇
  2016年   20857篇
  2015年   23790篇
  2014年   32729篇
  2013年   49154篇
  2012年   66736篇
  2011年   70451篇
  2010年   41617篇
  2009年   39478篇
  2008年   66810篇
  2007年   70609篇
  2006年   71948篇
  2005年   69281篇
  2004年   67715篇
  2003年   64849篇
  2002年   63237篇
  2001年   119757篇
  2000年   123538篇
  1999年   104084篇
  1998年   27620篇
  1997年   24716篇
  1996年   24606篇
  1995年   23723篇
  1994年   22004篇
  1993年   20783篇
  1992年   83189篇
  1991年   80513篇
  1990年   79063篇
  1989年   76425篇
  1988年   70409篇
  1987年   69199篇
  1986年   65665篇
  1985年   62960篇
  1984年   46496篇
  1983年   39862篇
  1982年   22881篇
  1981年   20240篇
  1980年   19067篇
  1979年   43564篇
  1978年   29948篇
  1977年   25809篇
  1976年   23644篇
  1975年   25607篇
  1974年   30795篇
  1973年   29689篇
  1972年   27707篇
  1971年   26105篇
  1970年   23957篇
  1969年   22720篇
  1968年   20618篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
BACKGROUND: Alternaria alternata is one of the most important allergenic fungi worldwide. Mannitol dehydrogenase (MtDH) has previously been shown to be a major allergen of Cladosporium herbarum and cross-reactivity has been demonstrated for several fungal allergens. OBJECTIVE: The present study's objective was to clone the MtDH from an A. alternata cDNA library, express and purify the recombinant non-fusion protein and test its IgE-binding properties. Methods A cDNA library prepared from A. alternata hyphae and spores was screened for mannitol dehydrogenase by DNA hybridization with the radioactively labelled C. herbarum homologue as a probe. The resulting clone was sequenced and heterologously expressed in Escherichia coli as a recombinant non-fusion protein, which was purified to homogeneity and analysed for its IgE-binding capacity. RESULTS: The coding sequence of the full-length cDNA clone comprises 798 bp encoding a protein with a molecular mass of 28.6 kDa and a predicted pI of 5.88. Protein sequence analysis revealed an identity of 75% and a homology of 86% between the MtDHs of A. alternata and C. herbarum. The functional mannitol dehydrogenase was expressed in the E. coli strain BL21(DE3) transformed with the vector pMW172 and purified to homogeneity. The enzyme catalyses the NADPH-dependent conversion of d-fructose to d-mannitol. In IgE-ELISA and immunoblots, MtDH is recognized by 41% of A. alternata-allergic patients. In vivo immunoreactivity of the recombinant MtDH was verified by skin prick testing. Finally, inhibition-ELISA experiments confirmed cross-reactivity between the MtDHs of A. alternata and C. herbarum. CONCLUSION: Mannitol dehydrogenase (Alt a 8) represents an important new allergen of the ascomycete A. alternata that might be suitable for improving diagnostic and therapeutic procedures.  相似文献   
994.
995.
996.
A diagnosis of sarcoidosis should be substantiated by pathological means in order to thoroughly exclude other diseases. The role of real-time endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in the diagnosis of sarcoidosis has not been reported. The purpose of the present study is to evaluate the diagnostic yield of EBUS-TBNA in demonstrating the pathological features of sarcoidosis. In total, 65 patients with suspected sarcoidosis, with enlarged hilar or mediastinal lymph nodes on computed tomography, were included in the study. Patients with a suspected or known malignancy or previously established diagnosis of sarcoidosis were excluded. Convex probe endobronchial ultrasonography integrated with a separate working channel was used for EBUS-TBNA. Surgical methods were performed in those in whom no granulomas were detected by EBUS-TBNA. Patients were followed up clinically. EBUS-TBNA was performed on a total of 77 lymph node stations in 65 patients. A final diagnosis of sarcoidosis was made for 61 (93.8%) of the patients. The remaining four patients were diagnosed as having Wegener's granulomatosis (n=1) or indefinite (n=3). In patients with a final diagnosis of sarcoidosis, EBUS-TBNA demonstrated noncaseating epithelioid cell granulomas in 56 (91.8%) of the patients. No complications were reported. Endobronchial ultrasound-guided transbronchial needle aspiration proved to be a safe procedure with a high yield for the diagnoses of sarcoidosis.  相似文献   
997.
998.
SETTING: Homes in Delhi, India. OBJECTIVE: To study the reach of mass media campaigns and their impact on awareness about tuberculosis (TB) control among homemakers/housewives. DESIGN: A community-based cross-sectional survey among homemakers residing in Delhi for more than 6 months. RESULTS: Of a total of 920 women interviewed, about 74.2% had seen specific TB-related health messages in one or more of the mass media. The maximum number of subjects could recall having seen billboards or television campaigns. The percentage of respondents who had correct information about various aspects of the disease was higher among those who had seen TB campaigns on any of the mass media. The effectiveness of radio and newsprint in communicating TB messages was found to be more limited than that of television and billboards. CONCLUSION: The mass media can be effective in getting messages about TB across to the community of women who are homemakers, especially in developing countries. In view of our findings, it may be recommended that television and billboards be used as tools for reaching out to them with specific campaigns regarding TB control, and that the use of these media should be strengthened further.  相似文献   
999.
SETTING: This paper describes an outbreak of human and related bovine tuberculosis (TB) caused by Mycobacterium caprae in Croatia. A 13-year-old boy clinically presented enlargement of cervical lymph node with consecutive isolation of M. caprae. His 7-year-old sister, who had no clinical signs of disease, hyper-reacted to the purified protein derivative (PPD) test (>25 mm) and peribronchial infiltration was found by radiology. The children came from a family that ran a small-sized cattle dairy farm. DESIGN: All cattle on the farm were subjected to cutaneous TB testing: six of the 14 reacted positive, while three were suspicious. The entire herd was slaughtered, their carcasses examined and collected material subjected to pertinent diagnostic procedures. RESULTS: Gross examination findings consistent with TB were observed in the PPD-positive cows. Mycobacteria isolated from the boy and cattle were identified by classical and molecular methods, confirming M. caprae as the causative agent. CONCLUSION: Although not bacteriologically proven, consumption of raw milk or non-pasteurised milk products from infected dairy cattle was suspected as the source of infection in humans. Our findings confirm the domination of M. caprae among cattle in Croatia and represent the first evidence of M. caprae infection in humans in Croatia.  相似文献   
1000.
Many types of seafood require cooking before ingestion and it has been demonstrated that this cooking process may affect the antigenicity and allergenicity of the food. We describe a case of anaphylaxis caused by selective sensitization to razor shell, a mollusc. In vivo and in vitro studies confirmed sensitization to boiled razor shell. Analysis of the nature of the allergen yielded results that were consistent with the findings of other authors and suggested that allergens involved in seafood allergy are commonly high molecular weight proteins that, in most cases, are heat stable.  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