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   2401篇
  免费   185篇
  国内免费   22篇
耳鼻咽喉   10篇
儿科学   60篇
妇产科学   47篇
基础医学   292篇
口腔科学   41篇
临床医学   284篇
内科学   559篇
皮肤病学   30篇
神经病学   224篇
特种医学   200篇
外科学   262篇
综合类   33篇
一般理论   1篇
预防医学   326篇
眼科学   39篇
药学   100篇
中国医学   17篇
肿瘤学   83篇
  2023年   12篇
  2022年   23篇
  2021年   56篇
  2020年   25篇
  2019年   35篇
  2018年   59篇
  2017年   39篇
  2016年   48篇
  2015年   40篇
  2014年   45篇
  2013年   89篇
  2012年   123篇
  2011年   123篇
  2010年   74篇
  2009年   65篇
  2008年   84篇
  2007年   116篇
  2006年   99篇
  2005年   81篇
  2004年   70篇
  2003年   70篇
  2002年   66篇
  2001年   62篇
  2000年   47篇
  1999年   50篇
  1998年   46篇
  1997年   34篇
  1996年   41篇
  1995年   34篇
  1994年   37篇
  1993年   29篇
  1992年   39篇
  1991年   36篇
  1990年   34篇
  1989年   59篇
  1988年   55篇
  1987年   42篇
  1986年   31篇
  1985年   44篇
  1984年   25篇
  1983年   19篇
  1982年   22篇
  1981年   17篇
  1980年   25篇
  1979年   27篇
  1977年   26篇
  1972年   15篇
  1971年   11篇
  1968年   14篇
  1966年   12篇
排序方式: 共有2608条查询结果,搜索用时 15 毫秒
1.
The ileocecal reservoir (Indiana pouch) is a large volume, low pressure continent reservoir well suited for urinary diversion. The mechanism of continence is believed to be the result of several factors, including the natural ileocecal valve resistance, resistance produced by the plication of the ileal segment and normal peristalsis of the ileum. We report the results of a video-urodynamic study in patients with an Indiana pouch, aimed at establishing the factors that contribute to continence and their relative significance. Video-urodynamic studies clearly demonstrate that continence in this type of urinary reservoir is dependent upon a synergism of the aforementioned factors in combination with the low intraluminal pressure of the detubularized bowel. Video-urodynamic studies offer an objective demonstration of the reservoir dynamics and its continence mechanisms, and provide an insight into the possible etiology of incontinence. Such studies also offer an objective means for critical comparison of the different continent urinary reservoirs.  相似文献   
2.
3.
4.
5.
Background The aim of the present study was to identify factors associated with the level of psychological distress reported by family carers of children with intellectual disability living in a large urban conurbation. Method Information was collected by postal questionnaire (or interview for family carers who did not have English as their first language) from the family carers of 408 children with intellectual disability (31% of all children within the area administratively identified as having an intellectual disability). Results Results indicated that 47% of primary carers scored above the threshold for psychological distress on the GHQ and that scoring above the threshold was strongly related to the emotional and behavioural needs of the index child and South‐Asian ethnicity and moderately associated with the severity of the child's delay in communication. Conclusions The rates of psychological distress (47% overall, 70% among South‐Asian carers) were markedly higher than that found in previous studies of carers supporting a child with intellectual disabilities. It is suggested that these elevated rates of psychological distress may be mediated by socio‐economic deprivation.  相似文献   
6.
Chitambar  CR; Zivkovic  Z 《Blood》1989,74(2):602-608
Information regarding transferrin (Tf) receptor degradation is largely incomplete. HL60 cells were shown to release to their growth medium a Tf-binding protein which could be immunoprecipitated by anti-Tf receptor monoclonal antibodies (MoAbs) B3/25 and OKT9. Soluble Tf receptor was detected in the medium within one hour of replating of cells, and its release was inhibited at 4 degrees C. The affinity of Tf for the soluble receptor released by cells (kd = 2.3 x 10(-10) mol/L) was slightly lower than its affinity for the detergent-solubilized cellular receptor (kd = 1.2 x 10(-10) mol/L). 125I-Tf internalized and released by cells subsequently bound to Tf receptor released by the same cells, and soluble Tf receptor in the conditioned medium (CM) inhibited 125I-Tf binding to intact cells. The soluble Tf receptor isolated from the CM was smaller (78,000 daltons) than the cell surface receptor (94,000 daltons) when analyzed by gel electrophoresis under reducing conditions. Isolated cell membranes readily released soluble receptor; however, this release could be blocked by protease inhibitors. The soluble Tf receptor may represent the extracytoplasmic domain of the cellular Tf receptor released from the surface of HL60 cells through proteolytic cleavage by a membrane-based protease.  相似文献   
7.
8.
The purpose of this study was to examine motor learning and retention given extensive practice in two fundamentally different movement sequences. One sequence was a memory-driven task (performing a series of whole body positions from memory) and the other a context-driven task (buttoning). Practice took place over 3 weeks, with performance measured weekly; retention was measured weekly for 3 weeks after practice. There were 7 people with Parkinson's disease (PD) and 7 age-matched neurologically healthy people who participated in this study. Both groups improved performance on both tasks with practice, with the majority of the change for the PD group occurring between 1 and 2 weeks of practice. Although those with PD did not necessarily perform as well as age-matched controls, they learned both sequences in a manner similar to age-matched controls, and exhibited retention across the 3-week retention interval. If people with PD are given sufficient practice they can learn and retain both memory-based and context-driven movement sequences as well as age-matched controls. The results provide support for maintaining physical activity and for intervention through movement therapy.  相似文献   
9.
Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).  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