首页 | 官方网站   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   5663篇
  免费   485篇
  国内免费   384篇
医药卫生   6532篇
  2024年   9篇
  2023年   52篇
  2022年   97篇
  2021年   211篇
  2020年   179篇
  2019年   195篇
  2018年   176篇
  2017年   158篇
  2016年   168篇
  2015年   278篇
  2014年   335篇
  2013年   277篇
  2012年   442篇
  2011年   428篇
  2010年   308篇
  2009年   246篇
  2008年   280篇
  2007年   371篇
  2006年   317篇
  2005年   316篇
  2004年   184篇
  2003年   189篇
  2002年   181篇
  2001年   158篇
  2000年   134篇
  1999年   146篇
  1998年   87篇
  1997年   95篇
  1996年   50篇
  1995年   55篇
  1994年   59篇
  1993年   39篇
  1992年   42篇
  1991年   38篇
  1990年   34篇
  1989年   33篇
  1988年   50篇
  1987年   30篇
  1986年   16篇
  1985年   18篇
  1984年   9篇
  1983年   4篇
  1982年   5篇
  1981年   5篇
  1979年   5篇
  1978年   4篇
  1975年   4篇
  1970年   3篇
  1964年   2篇
  1962年   3篇
排序方式: 共有6532条查询结果,搜索用时 437 毫秒
1.
Developmental dyslexia affects 40–60% of children with a familial risk (FHD+) compared to a general prevalence of 5–10%. Despite the increased risk, about half of FHD+ children develop typical reading abilities (FHD+Typical). Yet the underlying neural characteristics of favorable reading outcomes in at‐risk children remain unknown. Utilizing a retrospective, longitudinal approach, this study examined whether putative protective neural mechanisms can be observed in FHD+Typical at the prereading stage. Functional and structural brain characteristics were examined in 47 FHD+ prereaders who subsequently developed typical (n = 35) or impaired (n = 12) reading abilities and 34 controls (FHD?Typical). Searchlight‐based multivariate pattern analyses identified distinct activation patterns during phonological processing between FHD+Typical and FHD?Typical in right inferior frontal gyrus (RIFG) and left temporo‐parietal cortex (LTPC) regions. Follow‐up analyses on group‐specific classification patterns demonstrated LTPC hypoactivation in FHD+Typical compared to FHD?Typical, suggesting this neural characteristic as an FHD+ phenotype. In contrast, RIFG showed hyperactivation in FHD+Typical than FHD?Typical, and its activation pattern was positively correlated with subsequent reading abilities in FHD+ but not controls (FHD?Typical). RIFG hyperactivation in FHD+Typical was further associated with increased interhemispheric functional and structural connectivity. These results suggest that some protective neural mechanisms are already established in FHD+Typical prereaders supporting their typical reading development.  相似文献   
2.
Clinical Rheumatology - Since December 2019, the pandemic caused by coronavirus disease 2019 (COVID-19) raises a real public health problem. COVID-19 appeared in Wuhan (Hubei province) in China....  相似文献   
3.
4.
5.
目的 分析不同病理类型甲状旁腺功能亢进(PHPT)的临床表现特点。方法 回顾性分析1958-2005年北京协和医院收治经手术病理证实的280例PHPT患者的临床资料。按病理类型分为甲状旁腺腺瘤组208例,甲状旁腺增生组52例及甲状旁腺腺癌组20例。结果 腺癌组中男性高于另外2组(P〈0.05)。增生及腺癌组中骨畸形、骨软化比例较低,增生组骨吸收、病理性骨折比例低于腺瘤组;胃肠道症状、多饮多尿及泌尿系统病变在腺癌组中高于另外2组(P均〈0.05)。血总钙(TCa)、血游离钙离子(ICa)及24h尿Ca在腺癌组显著高于腺瘤组及增生组(P均〈0.01),在腺瘤组与增生组间差异无统计学意义(P〉0.05)。出现高钙危象的比例在腺癌组显著高于另外2组(P〈0.01)。腺癌组病灶重量高于增生组,腺瘤组病灶直径小于增生组(P均〈0.05)。结论 在本组病例中,腺癌组男性比例较高,泌尿系统病变更为多见,出现高钙危象的比例显著增高,术后复发的比例较高。增生组骨骼系统病变相对较轻,其病变甲状旁腺重量低于腺癌与腺瘤组。  相似文献   
6.
对60例临床疑为头痛型痛痫的患者进行24h脑电监测。结果表明:24h脑电监测对痛痫特殊类型的检出率明显高于常规EEG。在14例(23.3%)有痫样放电的患者中,出现痫样放电以睡眠期多于清醒期;且睡眠周期中以NREMⅠ,Ⅱ期最常见。对6例(16.2%)反复阵发出现高波幅额中线θ节律而无痫性放电的患者亦应考虑头痛型癫痫的诊断。  相似文献   
7.
本文重点论述人工生物材料的可靠性、安全性及其保证措施。  相似文献   
8.
The limitations of current methods of measuring bilirubin are well established and relate to the broad dynamic range and inability of the technique to determine different but structurally similar bilirubin species. New instrumentation and methodology circumvent these limitations, and clinical studies are beginning to reveal their increased diagnostic usefulness. Nevertheless, in several clinical situations, for example, the prediction of kernicterus, better bilirubin determinations may not eliminate the controversy surrounding appropriate therapeutic interventions.  相似文献   
9.
Splenic vein thrombosis with gastric variceal bleeding is difficult to manage, and splenectomy may be necessary to stop variceal bleeding. The authors report the case of a post-orthotopic liver transplant patient with bleeding gastric varices secondary to splenic vein thrombosis treated by partial splenic artery embolization. Successful embolization was performed via transcatheter approach depositing Gianturco coils into the intrasplenic artery resulting in immediate cessation of variceal bleeding. No recurrence of bleeding was noted postembolization. In conclusion, splenic artery embolization can be used as treatment for postliver transplant variceal bleeding with hypersplenism.  相似文献   
10.
Bone morphogenetic protein (BMP) was isolated from the bone matrix of swine and partially purified by means of differential precipitation and molecular sieve chromatography. The molecular weight of BMP estimated by SDS-gel electrophoresis was 19,000 dalton. Bioassay by implanting two milligrams of BMP fraction into thigh muscles of mice resulted in bone formation in 100% of the experimental animals.
  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-23

京公网安备 11010802026262号