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   2428篇
  免费   151篇
  国内免费   42篇
耳鼻咽喉   17篇
儿科学   124篇
妇产科学   16篇
基础医学   329篇
口腔科学   176篇
临床医学   215篇
内科学   590篇
皮肤病学   94篇
神经病学   121篇
特种医学   223篇
外科学   251篇
综合类   29篇
预防医学   182篇
眼科学   38篇
药学   124篇
中国医学   10篇
肿瘤学   82篇
  2023年   14篇
  2022年   36篇
  2021年   79篇
  2020年   59篇
  2019年   88篇
  2018年   85篇
  2017年   77篇
  2016年   56篇
  2015年   80篇
  2014年   83篇
  2013年   105篇
  2012年   137篇
  2011年   160篇
  2010年   119篇
  2009年   109篇
  2008年   116篇
  2007年   108篇
  2006年   125篇
  2005年   108篇
  2004年   62篇
  2003年   57篇
  2002年   41篇
  2001年   35篇
  2000年   37篇
  1999年   38篇
  1998年   56篇
  1997年   52篇
  1996年   55篇
  1995年   36篇
  1994年   43篇
  1993年   37篇
  1992年   20篇
  1991年   21篇
  1990年   18篇
  1989年   29篇
  1988年   53篇
  1987年   25篇
  1986年   27篇
  1985年   35篇
  1984年   12篇
  1983年   6篇
  1982年   9篇
  1981年   9篇
  1980年   10篇
  1979年   9篇
  1978年   5篇
  1977年   7篇
  1976年   12篇
  1972年   4篇
  1968年   3篇
排序方式: 共有2621条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Cecal intubation is a critical aspect of effective, complete colonoscopy. Difficult colonoscopy is most often considered as one in which it is challenging or impossible to reach the cecum. It may be a common occurrence due to patient and/or endoscopist factors. Incomplete colonoscopies should be avoided, since patients in this context present an important prevalence of lesions that escape examination. The approach to successful cecal intubation should depend on characterization of the problem as redundant colon or difficult sigmoid colon. Most patients with a prior incomplete colonoscopy can be colonoscoped successfully, if careful attention is paid to technique, using a variety of scopes, colonoscopy methods and additional equipment. Sufficient time should be allotted to make the attempt.  相似文献   
5.
6.
OBJECTIVE: The authors tested the effect of blood sampling (skin versus venous puncture) on some biochemical and hematological blood parameters in athletes to answer whether skin puncture could be used as a substitute for venous puncture. DESIGN: Comparative study of 2 methods of blood samples collection. SETTING: The blood was collected in the same athletes at 3 different moments of the preparatory training phase. PARTICIPANTS: Fourteen male indoor soccer players (22 +/- 1 years old) and 7 female handball players (18 +/- 1 years old) participated. MAIN OUTCOME MEASUREMENT: Blood was collected in heparin and K3EDTA by Vacutainer BD or Microvette Sarstedt system for biochemical and hematological analyses, respectively. RESULTS: There were no significant statistical differences between the 2 methods for the values of creatine kinase, urea, creatinine, lymphocytes, and platelets. The other hematological analyzes and uric acid exhibited significant higher values in skin blood, although they were all within the normal expected range. A high degree of correlation was observed between the 2 techniques for all parameters. CONCLUSIONS: Skin puncture is a reliable, easy, accurate, and less invasive sampling method for assessing hematological and some biochemical parameters in athletes, respecting that blood samples should always be obtained from the same site, especially in follow-up studies.  相似文献   
7.
BACKGROUND: Vitiligo is the most common pigmentary disorder with a global incidence from 0.1% to 2% in different geographical areas. Histopathology and histochemistry have shown the reduction of melanocytes in achromic patches, but microscopic changes of lesional and non-lesional skin are still not completely understood. Reflectance confocal microscopy (RCM), based on the different light reflectance index of cutaneous structures, allowed in vivo, en face microscopic evaluation of superficial skin layers with a resolution similar to skin histology. AIM: The purpose of this study was to evaluate RCM features of lesional and non-lesional skin of vitiligo patients. Moreover, re-pigmented areas were taken into consideration in order to evaluate melanocyte response to ultraviolet B (UVB) radiation. SUBJECTS AND METHODS: Sixteen patients of different phototypes affected by active non-segmental vitiligo and 10 controls were enrolled in the study. In vivo skin imaging was done using a commercially available RCM (Lucid, Vivascope 1500. Re-pigmented areas from 6 to 16 patients (after UVB narrow-band therapy) were also examined. RESULTS: Vitiligo lesions showed the disappearance of the bright rings normally seen at the dermo-epidermal junction. Moreover, non-lesional skin of vitiligo patients showed unexpected changes as the presence of half-rings or scalloped border-like features of the bright papillary rings. In re-pigmented areas after UVB narrow band therapy, the presence of activated, dendritic melanocytes was seen. CONCLUSIONS: Considering our results, and following further studies, RCM clinical applications could be used in the therapeutic monitoring and evaluation of the evolution of vitiligo.  相似文献   
8.
9.
10.
Leukoplakias are oral lesions that may have many clinical and histological aspects and they are usually associated with malignancy when dysplastic alterations are shown. However, these transformations may occur in non-dysplastic lesions that show harmless clinical aspect. For this reason, the proposal was to study the p53 and PCNA immunohistochemical expression in non-dysplastic leukoplakias, trying to correlate the results only with the epithelial keratinization degree. For this, 24 leukoplakias degrees I, II and III of Grinspan were used, all of them located in oral mucosa. Most of the leukoplakias showed p53 and PCNA expression in their different keratinization degrees. The p53 marking was confined to the basal and parabasal layers, while the PCNA marking occurred in practically all epithelial layers. The expression pattern of these markers was histologically and statistically similar between the lesions with these keratinization variations. It was evident that non-dysplastic epithelium of leukoplakias showed submicroscopical signs of alterations that lead to malignant transformation, and that the keratinization degree did not correlate to a greater risk of this event.  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