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   815篇
  免费   50篇
  国内免费   6篇
耳鼻咽喉   2篇
儿科学   15篇
妇产科学   18篇
基础医学   89篇
口腔科学   12篇
临床医学   98篇
内科学   194篇
皮肤病学   10篇
神经病学   30篇
特种医学   58篇
外科学   70篇
综合类   137篇
预防医学   27篇
眼科学   7篇
药学   45篇
中国医学   4篇
肿瘤学   55篇
  2022年   10篇
  2021年   8篇
  2020年   7篇
  2019年   9篇
  2018年   12篇
  2017年   4篇
  2016年   11篇
  2015年   17篇
  2014年   27篇
  2013年   25篇
  2012年   36篇
  2011年   28篇
  2010年   17篇
  2009年   27篇
  2008年   47篇
  2007年   54篇
  2006年   44篇
  2005年   33篇
  2004年   41篇
  2003年   37篇
  2002年   32篇
  2001年   46篇
  2000年   30篇
  1999年   22篇
  1998年   27篇
  1997年   31篇
  1996年   24篇
  1995年   9篇
  1994年   11篇
  1993年   7篇
  1992年   14篇
  1991年   14篇
  1990年   11篇
  1989年   10篇
  1988年   18篇
  1987年   13篇
  1986年   6篇
  1985年   9篇
  1984年   5篇
  1983年   5篇
  1982年   3篇
  1981年   9篇
  1980年   4篇
  1978年   3篇
  1976年   2篇
  1975年   4篇
  1974年   1篇
  1973年   1篇
  1970年   2篇
  1966年   1篇
排序方式: 共有871条查询结果,搜索用时 15 毫秒
1.
2.

Introduction  

Procalcitonin (PCT) has been proposed as a marker of infection in critically ill patients; its level is related to the severity of infection. We evaluated the value of PCT as a marker of bacterial infection for emergency department patients.  相似文献   
3.
4.
5.
Schick  PK; Wojenski  CM; Bennett  VD; Ivanova  T 《Blood》1996,87(5):1817-1823
There are several species of alternatively spliced fibronectin (FN). One of these, FN EIIIB, is primarily present in embryonic and in proliferating and migrating cells and is believed to be important for cell maturation. We have studied the synthesis, localization, and secretion of this FN isoform in isolated guinea pig megakaryocytes, nonmegakaryocytic bone marrow cells, and platelets. There was 7.5 times more general FN in megakaryocytes than in nonmegakaryocytic cells based on the analysis of equivalent amounts of protein. FN EIIIB was detected by Western blotting in megakaryocytes but not in nonmegakaryocytic cells present in bone marrow. Neither megakaryocytes nor platelets secreted FN EIIIB, while megakaryocytes secreted 25.3% +/- 4.6% general FN and platelets secreted about 61% general FN in response to thrombin. Analysis of immunostained cells by confocal microscopy revealed that FN EIIIB had been redistributed to the surface of megakaryocytes in response to thrombin. Synthesis was studied by metabolic labeling, and megakaryocytes were shown to synthesize FN and FN EIIIB. Thus, megakaryocytes and platelets are among a small number of adult cells and tissues that synthesize and contain FN EIIIB. The expression of FN EIIIB on the megakaryocyte surface may influence migration and maturation.  相似文献   
6.
7.
8.
Summary DNA enriched for supercoiled plasmids prepared from the 3 m plasmid-enriched, [ +], [2 m°] strain 6-1G-P188 and from the [2 m+] [+] strain LL20 can be used to transform a recipient strain to +. Fractionation of the former preparation by electrophoresis showed that the 3 Mm plasmid band contained the transforming activity.  相似文献   
9.
BACKGROUND: Peanut allergy is an important health problem in the United States, affecting approximately 0.6% of children. Inadvertent exposure to peanut is a risk factor for life-threatening food-induced anaphylaxis. OBJECTIVE: The purpose of this investigation was to develop an immunoassay for a major peanut allergen, Ara h 1, to detect peanut allergen in foods so that the risk of inadvertent exposure can be reduced. METHODS: A specific 2-site monoclonal antibody-based ELISA was developed to measure Ara h 1 in foods. The sensitivity of the assay was 30 ng/mL. Ara h 1 was measured in foods (n = 83) with or without peanut and in experiments to optimize allergen yield and to determine peanut contamination in spiked foods. RESULTS: Ara h 1 levels in food products ranged from less than 0.1 microg/g to 500 microg/g. Ara h 1 measured in ng/mL was transformed to microg/g for food products. Peanut butter contained the highest amounts of Ara h 1. Peanut extracts contained from 0.5 to 15 mg Ara h 1/g of peanut depending on the extraction conditions. Optimal extraction of Ara h 1 was obtained by using phosphate buffer with 1 mol/L NaCl and Tween at 60 degrees C. Ara h 1 was not always detected in presence of chocolate under the extraction conditions tested. Spiking experiments showed that the assay could detect approximately 0.1% Ara h 1 contamination of food with ground peanut. There was an excellent correlation between Ara h 1 levels and peanut content measured by using a commercial polyclonal antibody-based ELISA (r = 93, n = 31, P <.001). CONCLUSION: A new sensitive and specific monoclonal antibody-based ELISA was used to monitor Ara h 1 content in food products. This assay should be useful for monitoring peanut contamination in the food manufacturing and processing industry and in developing thresholds for sensitization or allergic reaction in persons with peanut allergy.  相似文献   
10.
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