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   4024篇
  免费   421篇
  国内免费   11篇
耳鼻咽喉   16篇
儿科学   191篇
妇产科学   67篇
基础医学   561篇
口腔科学   112篇
临床医学   508篇
内科学   742篇
皮肤病学   38篇
神经病学   284篇
特种医学   243篇
外国民族医学   1篇
外科学   470篇
综合类   130篇
一般理论   5篇
预防医学   465篇
眼科学   33篇
药学   236篇
中国医学   6篇
肿瘤学   348篇
  2021年   50篇
  2019年   46篇
  2018年   48篇
  2017年   47篇
  2016年   42篇
  2015年   61篇
  2014年   75篇
  2013年   159篇
  2012年   154篇
  2011年   173篇
  2010年   99篇
  2009年   89篇
  2008年   186篇
  2007年   156篇
  2006年   139篇
  2005年   127篇
  2004年   170篇
  2003年   149篇
  2002年   158篇
  2001年   154篇
  2000年   121篇
  1999年   129篇
  1998年   51篇
  1997年   62篇
  1996年   53篇
  1995年   45篇
  1994年   48篇
  1993年   40篇
  1992年   105篇
  1991年   80篇
  1990年   81篇
  1989年   86篇
  1988年   78篇
  1987年   90篇
  1986年   87篇
  1985年   91篇
  1984年   57篇
  1983年   50篇
  1981年   30篇
  1980年   36篇
  1979年   67篇
  1978年   38篇
  1974年   43篇
  1973年   47篇
  1972年   49篇
  1971年   45篇
  1970年   36篇
  1969年   46篇
  1968年   39篇
  1967年   32篇
排序方式: 共有4456条查询结果,搜索用时 15 毫秒
1.
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
2.
3.
4.
5.
We have described a method for the microtransplantation of a suspension of a few thousand cells from mid to late embryonic mouse hippocampi into the fimbria of immunosuppressed adult rat hosts. There was close graft-to-host contact, across a non-scarred interface. The transplanted cells included CA3 type pyramids, and were enclosed within the host myelinated fibre tract, whose glial framework was largely undisturbed. Immunohistochemistry of two species-specific markers (M6 and Thy-1.2) showed that the donor mouse neurons grew fine (<0.5 μm diameter) axons which extended singly or in fascicles through the rat host fimbria for a maximum distance of at least 10 mm. The donor axons were intimately integrated among and closely aligned to the host tract axons and to the interfascicular glial rows of the host tract. The axons travelled (i) laterally through the ipsilateral fimbria, (ii) medially across the midline in the ventral hippocampal commissure to reach the contralateral fimbria and alveus, and (iii) rostro-medially to the septum. On approaching the terminal fields appropriate to hippocampal CA3 pyramidal cell axons, the transplant axons gave rise to fine preterminal branches which were continuous with a reticular or amorphous immunoreactivity in the stratum oriens and stratum pyramidale of the ipsilateral hippocampus, and in the lateral and triangular septal nuclei. The donor axons extended along the host fimbria at a rate of ∼ 1 mm per day, reaching their terminal field destinations by ∼1–2 weeks. At 7 weeks the projections were maintained, but with little further extension. These observations indicate that the microenvironment of myelinated adult fibre tracts is permissive for an abundant and rapid growth of axons from transplanted embryonic cell suspensions. These axons can leave host tracts to invade appropriate terminal fields.  相似文献   
6.
7.
8.
9.
Forty normal one-month-old infants were randomly assigned to a breast-like nipple (Healthflow) bottlefeeding or a standard nipple (Evenflo) bottlefeeding group for one 20-minute feeding by the infants' mothers. The data suggested that the mothers' bottlefeeding behaviors did not differ, but the infants who fed on the breast-like nipples spent less time asleep, more time awake and active and less time fussing and crying. In addition, the vagal tone of that group decreased more during bottlefeeding and increased more after the feeding, suggesting that the breast-like nipple bottlefeedings were more similar to breastfeedings (vagal tone being lower during breastfeeding and higher after breastfeeding versus bottlefeeding). Because many women who breastfeed return to work, bottlefeeding that more closely approximate breastfeedings may ease this transition and may provide more effective supplemental feedings for the breastfed infants.  相似文献   
10.
In this study, ethnographic interviews were used to identify first-time fathers' experiences of the birth of their first child. Fourteen fathers were interviewed, and prenatal expectations of the experience are compared with the fathers' perceptions after the birth. Although the fathers expected to be treated as part of a laboring couple, they found that they were relegated to a supporting role. Initially the fathers were confident of their ability to support their wives, but they found that labor was more work than they had anticipated. They became fearful of the outcome, but hid these fears from their partners. Later, they found that their focus moved from their wives to their babies at the time of birth. The men all completed the experience with an enhanced respect for their wives. Fathers should be included in labor management plans and need support for their role as coach, particularly when their wives experience pain. They also need to be encouraged to eat and take a break from their wives' labor when appropriate.  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