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   2498篇
  免费   168篇
  国内免费   11篇
耳鼻咽喉   20篇
儿科学   84篇
妇产科学   40篇
基础医学   447篇
口腔科学   61篇
临床医学   173篇
内科学   635篇
皮肤病学   120篇
神经病学   232篇
特种医学   42篇
外科学   228篇
综合类   10篇
一般理论   3篇
预防医学   112篇
眼科学   59篇
药学   150篇
中国医学   13篇
肿瘤学   248篇
  2023年   18篇
  2022年   31篇
  2021年   43篇
  2020年   27篇
  2019年   50篇
  2018年   48篇
  2017年   56篇
  2016年   75篇
  2015年   68篇
  2014年   79篇
  2013年   110篇
  2012年   165篇
  2011年   205篇
  2010年   92篇
  2009年   91篇
  2008年   155篇
  2007年   186篇
  2006年   167篇
  2005年   153篇
  2004年   190篇
  2003年   177篇
  2002年   158篇
  2001年   24篇
  2000年   13篇
  1999年   26篇
  1998年   35篇
  1997年   20篇
  1996年   17篇
  1995年   11篇
  1994年   17篇
  1993年   16篇
  1992年   18篇
  1991年   17篇
  1990年   12篇
  1989年   7篇
  1988年   7篇
  1987年   11篇
  1986年   7篇
  1985年   5篇
  1984年   5篇
  1983年   11篇
  1982年   11篇
  1981年   5篇
  1980年   8篇
  1979年   3篇
  1978年   4篇
  1977年   7篇
  1976年   3篇
  1975年   4篇
  1969年   3篇
排序方式: 共有2677条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
The data on visceral mycoses reported in the " Annual of Pathological Autopsy Cases in Japan " were analyzed epidemiologically every four years from 1989 to 2005, and in 2007. The frequency rates of visceral mycoses dropped sharply between 1989 (4.5%) and 1994 (3.2%), but by 2001 had risen again and have remained (4.4-4.6%) generally stable since then. The predominant causative agents were Candida and Aspergillus. Although the rate of candidosis showed a gradual decrease, the rate of aspergillosis showed an increase by degrees. Furthermore, the rate of aspergillosis exceeded that of candidosis in 1994, and the difference in the rates between the two conditions apparently further increased until 2001. After 2005, however no changes in this difference were observed. For complicated infections, the incidence of coinfection with Aspergillus and Candida showed a decreasing, and that with Aspergillus and Zygomycetes showed an increasing tendency. Severe infections with Zygomycetes showed a clear increase from 57.4% in 1989 to 88.9% in 2007. Comparing underlying diseases with mycoses in 1989 and 2007, leukemia (including myelodysplastic syndrome) decreased from 26.1% to 18.8% and bacterial infections (including interstitial pneumonia) increased from 11.1% to 22.1%. By age, the highest frequency rate of mycoses was observed in the range of 60-79 years, and the frequency rate of exogenous fungal infections such as aspergillosis, cryptococcosis, zygomycosis and trichosporonosis showed an increasing trend in the less than one-year old group.  相似文献   
996.
997.
Silk fibroin fiber has a long history of use in sutures because of its high strength and toughness. In the work reported in this paper, small-diameter vascular grafts 1.5 mm in diameter and 10 mm in length were prepared by coating a double-raschel knitted silk fiber graft with silk fibroin aqueous solution containing poly(ethylene glycol diglycidyl ether) as a cross-linking agent. The most important character of silk fibroin graft is remodeling, which is never observed for polyester fiber or expanded polytetrafluoroethylene grafts. The double-raschel knitted silk fiber graft with coating has sufficient physical strength and protects the ladder from the end in the implantation process. The coating also gives protection against leakage of blood from the graft, and elasticity to the graft. Eight weeks after implantation of the grafts in rat abdominal aorta, early formation of thrombosis was avoided.  相似文献   
998.
ESCs are most commonly derived from embryos originating from oocytes that reached metaphase II. We describe here a novel approach where ESCs with all pluripotency parameters were established from oocytes in which metaphase I was converted, from the cell cycle perspective, directly into metaphase II-like stage without the intervening anaphase to telophase I transition. The resulting embryos initiate development and reach the blastocyst stage from which the ESC lines are then established. Thus, our approach could represent an ethically acceptable method that can exploit oocytes that are typically discarded in in vitro fertilization clinics. Moreover, our results also indicate that the meiotic cell cycle can be converted into mitosis by modulating chromosomal contacts that are typical for meiosis with subsequent licensing of chromatin for DNA replication.  相似文献   
999.
1000.
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