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   3430430篇
  免费   241334篇
  国内免费   9375篇
耳鼻咽喉   48379篇
儿科学   111459篇
妇产科学   97265篇
基础医学   481771篇
口腔科学   97186篇
临床医学   308493篇
内科学   669738篇
皮肤病学   81693篇
神经病学   279967篇
特种医学   132670篇
外国民族医学   1122篇
外科学   516414篇
综合类   72785篇
现状与发展   11篇
一般理论   1301篇
预防医学   256868篇
眼科学   79096篇
药学   252471篇
  12篇
中国医学   7127篇
肿瘤学   185311篇
  2018年   35987篇
  2017年   27945篇
  2016年   32156篇
  2015年   36208篇
  2014年   50075篇
  2013年   75581篇
  2012年   99753篇
  2011年   105654篇
  2010年   63744篇
  2009年   61119篇
  2008年   99334篇
  2007年   106304篇
  2006年   107853篇
  2005年   103741篇
  2004年   100199篇
  2003年   97059篇
  2002年   93951篇
  2001年   160872篇
  2000年   164938篇
  1999年   139514篇
  1998年   40151篇
  1997年   35817篇
  1996年   35460篇
  1995年   34215篇
  1994年   31556篇
  1993年   29592篇
  1992年   109073篇
  1991年   105318篇
  1990年   102331篇
  1989年   99256篇
  1988年   91553篇
  1987年   89806篇
  1986年   84829篇
  1985年   81075篇
  1984年   60764篇
  1983年   51624篇
  1982年   30927篇
  1981年   27709篇
  1979年   55252篇
  1978年   39255篇
  1977年   33841篇
  1976年   31034篇
  1975年   34024篇
  1974年   40105篇
  1973年   38498篇
  1972年   36376篇
  1971年   33948篇
  1970年   31661篇
  1969年   30542篇
  1968年   28342篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
992.
993.
994.
Renal transplantation has provided women of childbearing age with increased fertility and the possibility of successful pregnancy outcomes. Approximately 14,000 births among women with transplanted organs have been reported worldwide, but pregnancy complications have been frequent: spontaneous or therapeutic abortion, preterm birth, low birth weight, and intrauterine growth restriction. Herein we have described a case of an acute rejection episode in a renal transplant recipient, occurring 6 months after successful delivery, despite the fulfillment of all European best practice guidelines criteria and the maintenance of adequate immunosuppression. Our case demonstrated that even a presumably low-risk patient can face worsening of renal function during or after pregnancy. Acute immune activation is uncommon but may occur in late-onset fashion. Despite adequate levels of maintenance immunosuppression, there is a risk of developing antibodies against the partner or the donor, causing acute renal immune damage.  相似文献   
995.
In 2002/2005, separate energy requirement equations were generated by the Institute of Medicine's (IOM) Dietary Reference Intake process for normal weight and overweight/obese children and adolescents. The current paper questions the theoretical rationale of having two sets of equations (based solely on body-weight classification): when body weight is considered, overweight and obese children and adolescents do not seem to differ from their normal weight counterparts in energy expended for basal metabolism or physical activity tasks. However, energy needs for weight maintenance among overweight/obese girls were consistently higher when predicted using the equations for overweight/obese individuals compared with those developed for normal weight individuals. In contrast, among overweight/obese boys, they were consistently lower . Although the differences are within the variability of the estimates, even theoretical support for a higher energy intake (as occurs in girls) seems unwise because of the potential contribution to a higher body mass in children who are already at risk. It is the opinion of the authors that the IOM revisit the use of two separate equations and generate one set that is appropriate for all children and adolescents.  相似文献   
996.
997.
Protracted or recurrent pain and inflammation in the early neonatal period may cause long-lasting changes in central neural function. However, more research is necessary to better characterize the long-term behavioral sequelae of such exposure in the neonatal period. Objectives: (1) to study whether timing of postnatal exposure to persistent inflammation alters responsiveness to thermal pain in the adult animal; (2) to assess whether animals experiencing early postnatal chronic inflammation display altered anxiety related behavior; (3) to study the importance of genetic background. Newborn mice (outbred strain, CD1 and F1 hybrid strain, B6C3F1) received an injection of Complete Freund's Adjuvant (CFA) or saline on either postnatal day 1 or 14 (PND1; PND14) into the left hind paw. Pain to radiant heat and anxiety were examined in 12-week-old adult animals. Adult baseline PWL was significantly decreased in CD1 mice exposed to CFA on PND 1 and 14 as compared to their saline treated counterparts. B6C3F1 mice exposed to CFA on PND14 showed markedly reduced baseline PWL compared to the PND14 saline group. Persistent inflammation experienced by B6C3F1 mice on PND1 failed to affect baseline adult thermal responsiveness. Adult mice, CD1 and B6C3F1, displayed low anxiety traits only if they had been exposed to persistent inflammation on PND1 and not on PND14. Our research suggests a role for genetic background in modulating long-term behavioral consequences of neonatal persistent inflammation: the data support the hypothesis that pain experienced very early in life differentially affects adult behavioral and emotional responsiveness in outbred (CD1) and hybrid mice (B6C3F1).  相似文献   
998.
999.
Contrary to popular beliefs, a recent empirical study using eye tracking has shown that a non-clinical sample of socially anxious adults did not avoid the eyes during face scanning. Using eye-tracking measures, we sought to extend these findings by examining the relation between stable shyness and face scanning patterns in a non-clinical sample of 11-year-old children. We found that shyness was associated with longer dwell time to the eye region than the mouth, suggesting that some shy children were not avoiding the eyes. Shyness was also correlated with fewer first fixations to the nose, which is thought to reflect the typical global strategy of face processing. Present results replicate and extend recent work on social anxiety and face scanning in adults to shyness in children. These preliminary findings also provide support for the notion that some shy children may be hypersensitive to detecting social cues and intentions in others conveyed by the eyes. Theoretical and practical implications for understanding the social cognitive correlates and treatment of shyness are discussed.  相似文献   
1000.
When studying histological characteristics of human and porcine pancreata in relation to islet isolation, we encountered a remarkably high number of hyperemic islets. The abnormalities observed in these islets ranged from a single dilated vessel through multiple widely dilated vessels to hemorrhages extending into the surrounding exocrine tissue. We determined their possible relevance for outcomes of islet isolation. This study involved a histological examination of 143 porcine pancreata (72 juvenile and 71 adult) and islet isolation from 48 adult pancreata. Human pancreata obtained from 71 multiple organ donors yielded islet isolation in 24 cases. To determine their endocrine content, tissue samples were stained with Aldehyde Fuchsin. The presence of hyperemic islets was scored semiquantitatively with pancreata allotted to categories based on the severity. In humans and pigs we observed hyperemic islets in 48% of pancreata, but only 4.0 ± 2.4% of the islets were hyperemic. In both humans and pigs, significantly higher endocrine content was found in the most severely affected pancreata. When the higher endocrine content was taken into account and isolation results were expressed as ratios of yield and content, we observed significantly lower yields in the most affected pancreata in pigs with a trend toward lower yields in humans. A substantial proportion of human and porcine pancreata contain hyperemic islets. Although the results in humans are preliminary, our data suggest that this phenomenon may contribute to the unpredictable, highly variable islet yields in pigs and humans.  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