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   7790篇
  免费   674篇
  国内免费   33篇
耳鼻咽喉   58篇
儿科学   369篇
妇产科学   221篇
基础医学   919篇
口腔科学   133篇
临床医学   932篇
内科学   1317篇
皮肤病学   64篇
神经病学   726篇
特种医学   352篇
外科学   1271篇
综合类   169篇
一般理论   2篇
预防医学   747篇
眼科学   166篇
药学   547篇
中国医学   4篇
肿瘤学   500篇
  2021年   109篇
  2020年   65篇
  2019年   97篇
  2018年   119篇
  2017年   92篇
  2016年   98篇
  2015年   114篇
  2014年   142篇
  2013年   258篇
  2012年   295篇
  2011年   342篇
  2010年   186篇
  2009年   167篇
  2008年   306篇
  2007年   343篇
  2006年   350篇
  2005年   298篇
  2004年   297篇
  2003年   266篇
  2002年   264篇
  2001年   291篇
  2000年   288篇
  1999年   269篇
  1998年   157篇
  1997年   119篇
  1996年   114篇
  1995年   109篇
  1994年   85篇
  1993年   80篇
  1992年   193篇
  1991年   184篇
  1990年   189篇
  1989年   157篇
  1988年   176篇
  1987年   140篇
  1986年   151篇
  1985年   145篇
  1984年   137篇
  1983年   111篇
  1982年   75篇
  1981年   64篇
  1980年   55篇
  1979年   107篇
  1978年   76篇
  1977年   68篇
  1976年   52篇
  1975年   75篇
  1974年   74篇
  1973年   77篇
  1972年   63篇
排序方式: 共有8497条查询结果,搜索用时 343 毫秒
101.
BackgroundShort gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis.MethodsFemale juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature.ResultsA statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ± 0.7 vessels, after: 4.7 ± 1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ± 3.0 vessels/mm, spring: 7.0 ± 9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ± 3.0 vessels/mm, spring: 8.0 ± 8.0 vessels/mm, p = 0.003).ConclusionIntestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine.Level of evidenceN/AType of studyTreatment study.  相似文献   
102.
Introductionshort bowel syndrome is marked by inadequate intestinal surface area to absorb nutrients. Current treatments are focused on medical management and surgical reconfiguration of the dilated intestine. We propose the use of spring-mediated distraction enterogenesis as a novel intervention to increase intestinal length. Given our previous success lengthening intestinal segments using springs with spring constant ~7 N/m that exerts 0.46 N or higher, we sought to determine the minimal force needed to lengthen porcine small intestinal segments, and to explore effects on intestine over time.MethodsJuvenile Yucatan pigs underwent laparotomy with enterotomy to introduce nitinol springs intraluminally (n = 21 springs). Bowel segments (control, spring-distracted) were retrieved on post-operative day (POD) 7 and 14, and lengths measured. Thickness of cross-sectional intestinal layers were measured using H&E, and submucosal collagen fiber orientation measured using trichrome stained sections.Resultsall pigs survived to POD7 and 14. Spring constants of at least 2 N/m exerting a minimum force of 0.10 N significantly lengthened intestinal segments (p <0.0001). The stronger the spring force, the greater the induced thickness of various intestinal layers at POD7 and 14. Collagen fiber orientation was also more disordered because of stronger springs.Conclusiona spring constant of approximately 2 N/m exerting 0.10 N and greater significantly lengthens intestinal segments and stimulates intestinal structural changes at POD7 and 14. This suggests a decreased force is capable of inducing spring-mediated distraction enterogenesis.  相似文献   
103.
104.
BackgroundThe aetiology of chronic therapy resistant plantar fasciitis (CTRPF) is multifactorial with more focus in recent times on the gastroc-soleus complex. This study evaluates the effect of lengthening the gastrocnemius muscle in CTRPF.MethodsAll patients with CRTPF complaints for at least one year underwent the same standard conservative treatment prior to surgery. 32 patients failed this treatment and underwent gastrocnemius recession. Silfverskiöld test, questionnaires and plantar pressure measurements were obtained at 5 visits.ResultsOne year follow up showed a significantly increase in dorsiflexion of the ankle (16 degrees), a decrease in VAS; 78 (SD: 19) to 20 (SD: 24) and significant improved functional scores. Plantar pressure measurements showed an increase of pressure under the medial proximal part of the midfoot and the 1 st metatarsal and a decrease under the hallux.ConclusionsA gastrocnemius recession results in a significant gain in dorsiflexion, altered loading of the foot and good clinical outcome in patients with CTRPF.Level of EvidenceLevel 2  相似文献   
105.
106.
Viral hepatitis     
Viral hepatitis is the most common serious contagious disease caused by viruses that attack the liver. Approximately 70,000 cases are reported to the Centers for Disease Control each year, representing only a fraction of U.S. cases. There are five types of viral hepatitis currently known: Hepatitis A--formerly called infectious hepatitis; Hepatitis B--formerly called serum hepatitis, and the most serious form; Hepatitis C--formerly called non-A, non-B hepatitis; Hepatitis D--formerly called delta hepatitis; Hepatitis E--formerly called enteric or epidemic non-A, non-B hepatitis. The following Open Forum, prepared by leading EMS experts, explores the differences among the types of hepatitis, signs and symptoms, and EMS implications.  相似文献   
107.
108.
109.
Comprehensive quality management is a goal that requires major corporate commitment to implement and maintain. The best results in a quality management program will be achieved when all components are tied together in a comprehensive program. To do that, a significant investment in personnel and equipment is required. As the benefits of having a program such as the one as described above become more widely known and accepted, more and more managed care insurers and providers will adopt these or similar standards. The question, "How do you know that patients are getting high-quality and sufficient care?" cannot be answered today by insurers who do not have such a program.  相似文献   
110.
Seizures are a frequent sequela of impaired brain development and can be expected to affect more children with radiation-related brain damage than children without such damage. This report deals with the incidence and type of seizures among survivors prenatally exposed to the atomic bombing of Hiroshima and Nagasaki, and their association with specific stages of prenatal development at the time of irradiation. Fetal radiation dose was assumed to be equal to the dose to the maternal uterus. Seizures here include all references in the clinical record to "seizure," "epilepsy," or "convulsion." Histories of seizures were obtained at biennial routine clinical examinations starting at about the age of 2 years. These clinical records were used to classify seizures as febrile or unprovoked (without precipitating cause). No seizures were ascertained among subjects exposed 0-7 weeks after fertilization at doses higher than 0.10 Gy. The incidence of seizures was highest with irradiation at the eighth through the 15th week after fertilization among subjects with doses exceeding 0.10 Gy and was linearly related to the level of fetal exposure. This obtains for all seizures without regard to the presence of fever or precipitating causes, and for unprovoked seizures. When the 22 cases of severe mental retardation were excluded, the increase in seizures was only suggestively significant and only for unprovoked seizures. After exposure at later stages of development, there was no increase in recorded seizures.  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