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   1821篇
  免费   105篇
  国内免费   44篇
耳鼻咽喉   8篇
儿科学   104篇
妇产科学   14篇
基础医学   138篇
口腔科学   35篇
临床医学   158篇
内科学   326篇
皮肤病学   24篇
神经病学   55篇
特种医学   163篇
外科学   170篇
综合类   231篇
预防医学   145篇
眼科学   17篇
药学   170篇
中国医学   79篇
肿瘤学   133篇
  2023年   15篇
  2022年   17篇
  2021年   37篇
  2020年   27篇
  2019年   18篇
  2018年   21篇
  2017年   38篇
  2016年   30篇
  2015年   39篇
  2014年   68篇
  2013年   89篇
  2012年   108篇
  2011年   131篇
  2010年   100篇
  2009年   102篇
  2008年   119篇
  2007年   100篇
  2006年   86篇
  2005年   71篇
  2004年   54篇
  2003年   55篇
  2002年   54篇
  2001年   49篇
  2000年   37篇
  1999年   40篇
  1998年   32篇
  1997年   29篇
  1996年   27篇
  1995年   17篇
  1994年   14篇
  1993年   13篇
  1992年   20篇
  1991年   31篇
  1990年   21篇
  1989年   32篇
  1988年   24篇
  1987年   21篇
  1986年   18篇
  1985年   19篇
  1984年   13篇
  1983年   16篇
  1982年   11篇
  1981年   14篇
  1980年   9篇
  1979年   12篇
  1978年   12篇
  1977年   15篇
  1976年   7篇
  1975年   12篇
  1971年   4篇
排序方式: 共有1970条查询结果,搜索用时 31 毫秒
71.
There is evidence of the existence of a bidirectional relationship between the thymus gland and the thyroid axis. Since the thymic peptide thymulin possesses hypophysiotropic activity, we undertook the task of assessing the histomorphometric changes induced by thymulin deficiency on the thyrotrope population of normal mice and the action of neonatal thymulin gene therapy on the thyrotropin (TSH)-cells of nude mice. C57BL/6 mice were subjected to immunoneutralization of circulating thymulin from postnatal day 1 to the end of the study (postnatal day 32) by intraperitoneal injections of rabbit anti-factor thymulin serum (α-FTS) and normal rabbit serum in controls. Also, neonatal thymulin gene therapy was implemented in athymic nude mice using an adenoviral vector expressing a gene for thymulin (RAd-FTS). On postnatal day 1, heterozygous (nu/+) and homozygous (nu/nu) pups received a single bilateral intramuscular (i.m.) injection of either RAd-FTS or RAd-GFP (the latter being the control vector). The pituitaries were immunostained for TSH. Thymulin immunoneutralization severely reduced serum thymulin (p < 0.01). We detected a significant (p < 0.05) decrease in cell size (CS) and volume density (VD) with a nonsignificant decrease in cell density (CD) in C57BL/6 in both males and females. A single neonatal i.m. injection of RAd-FTS markedly increased the circulating levels of serum thymulin in the athymic mice and increased the CD (p < 0.05), CS (p < 0.01) and VD (p < 0.01) of the thyrotrope population in nu/nu mice. Thyroid histology was not affected. Our results suggest a possible modulating effect of thymulin on the thyrotrope population.  相似文献   
72.
A variety of pathological changes are seen in lymphoproliferative disorders of the lung but the histogenesis of these abnormalities is not yet fully understood. We previously showed that adenovirus vector-mediated transient expression of both the human interleukin-6 (IL-6) and IL-6 receptor (IL-6R) genes, but not the IL-6 gene alone, in the rat lung induced lymphocytic alveolitis. In the present study, we explored the lung pathology of human IL-6 and IL-6R double transgenic mice to elucidate the effects of prolonged IL-6 signalling on the lung. The transgenic animals developed mononuclear cell accumulation in peribronchovascular regions, but little infiltration into alveolar spaces. Immunohistochemical analysis revealed that the cellular accumulations contained not only mixtures of inflammatory cells but also lymphoid tissue-like structures. As the expression of CXCL13/BLC, the indispensable chemokine for lymphoid organogenesis, was recognized in the B cell follicles of the pulmonary lesions, we speculate that this chemokine plays an inductive role in the development of the lymphoid tissue-like structures. These structures were distinguished from bronchus-associated lymphoid tissues (BALTs) by their location and by the lack of lymphoepithelium, which is a characteristic of BALT. These findings imply that IL-6 signalling may play a role in the pathogenesis of lymphoproliferative disorders of the lung.  相似文献   
73.
目的:探讨高血压丘脑出血破入脑室的治疗方法。方法:回顾分析本院高血压丘脑出血破入脑室30例患者的临床资料,15例行双侧脑室外引流术,6例行血肿穿刺引流+脑室外引流,5例行开颅血肿清除,4例意识清醒。结果:生活自理18例,中残6例,重残3例,死亡3例。结论:高血压丘脑出血破入脑室者应急诊行脑室外引流。  相似文献   
74.
导管室介入封堵及外科小切口介入封堵都已经被广泛地应用于临床,封堵成功的关键在于经胸与经食管超声心动图在术前对病例精确的筛选、术中监测及术后即刻评价。文章结合目前国内外文献及临床病例,对经胸与经食管超声心动图在房间隔缺损、室间隔缺损和动脉导管未闭3种常见先天性心脏病介入治疗中的应用进行综述,为临床提供更加准确的超声影像学诊断依据。  相似文献   
75.
目的:观察携带目的基因的大鼠骨髓间充质干细胞(mesenchymal stem cells ,MSCs) 静脉移植在严重烫伤延迟复苏损伤体内的分布.方法:分离培养MSCs,用Ad-GFP转染MSCs,25只Wistar大鼠随机分为延迟复苏组(A组,10只)、即时复苏组(B组,10只)、假伤组(C组,5只).A、B两组大鼠背部造成Ⅲ度30%烫伤,制备A组为延迟复苏模型,B组为即时复苏模型,同时制备C组为假伤模型,经股静脉移植转染Ad-GFP 48 h后的MSCs.24 h,7 d后取小肠、肝脏、肾脏、烫伤皮肤创缘等组织,快速冰冻切片,荧光显微镜下观察在体内的分布.结果:MSCs 体外分离培养扩增5代,细胞数可达(1~2)×1011个,具有多态性和贴壁生长特性,MOI=100时,Ad-GFP转染MSCs效率可达86.4%.经股静脉移植24 h,在延迟复苏组烫伤皮肤组织创缘,小肠黏膜广泛可见绿色荧光,而在肝、肺等器官少见,即时复苏组荧光以烫伤皮肤创缘分布为主,小肠黏膜较少,假伤组中绿色荧光分布以肝脏为主.延迟复苏组小肠荧光强度明显强于即时复苏组和假伤组(P《0.05),而延迟和即时复苏组皮肤创缘荧光强度又强于假伤组(P《0.05).结论:导入目的基因可能不会改变MSCs归巢特性,并将为后续启动基因治疗烧伤延迟复苏后的损伤研究提供参考.  相似文献   
76.
基于薄板样条和形状内容的医学图像非刚性配准方法研究   总被引:2,自引:0,他引:2  
目的 针对医学图像非刚性点配准的现状,给出一种基于点特征的非刚性配准方法.方法 利用一种新的相似度测量方法--形状内容来解决两幅图像中点的对应关系,并利用点对应关系来估计非刚性映射函数.结果 利用薄板样条实现了医学图像的快速准确非刚性配准.结论 实验结果表明,上述方法获得了很好的配准效果.  相似文献   
77.
富氧对缺氧大鼠心肌琥珀酸脱氢酶及超微结构的影响   总被引:2,自引:0,他引:2  
目的:探讨富氧对缺氧大鼠心肌损伤的保护作用及机理。方法:雄性Wistar大鼠32只随机分为平原对照组、低氧组、富氧组,低氧组在模拟海拔5400m低压舱内24h,富氧组在模拟5400m的低压舱内12h,然后富氧(27.0%的氧混合气)12h,观察心肌琥珀酸脱氢酶(SDH)及超微结构的改变。结果:低氧组心肌细胞灶性变性坏死,肌丝溶解凝固,间质水肿液和纤维素样渗出。富氧组心肌无明显病变,仅滑面内质网轻度扩张。富氧组SDH活性明显高于低氧组。结论:低氧导致心肌SDH活性及超微结构的改变,富氧对心肌有保护作用。  相似文献   
78.
In a prospective study of 65 patients with bile duct obstruction, various radiologic modalities were compared for their capability to demonstrate the level and cause of obstruction and to indicate accurately tumor resectability. Ultrasound (US) was performed in 65 patients, computed tomography (CT) in 51, direct cholangiography (DC) in 57, and angiography in 35. The level of obstruction was correctly indicated by US in 95% of patients and by CT in 90%, and the cause was correctly indicated by US in 88%, by CT in 63%, and by DC in 89%. In predicting tumor resectability, US was correct in 71% of patients, compared with 42% for CT, 58% for DC, and 25% for angiography. US therefore appears to be the single most useful modality in the evaluation bile duct obstruction.  相似文献   
79.
80.
Identification of T lymphocytes in human mixed hemopoietic colonies   总被引:11,自引:0,他引:11  
Messner  HA; Izaquirre  CA; Jamal  N 《Blood》1981,58(2):402-405
The addition of a T-cell growth-promoting medium (PHA-TCM) to culture conditions that support growth of multi-lineage hemopoietic colonies enhances the proliferation of cells with lymphoid morphology within these colonies. These cells were identified as T lymphocytes by their ability to form rosettes with SRBC and their reaction with monoclonal antibodies (OKT3, OKT4) directed against T-cell-specific surface components. They continue to proliferate extensively under the influence of PHA-TCM after transfer of mixed colonies into liquid suspension culture. Supportive evidence for a common progenitor of myeloid and lymphoid cells within single mixed colonies is provided by Y-chromatin body analysis of E-rosette positive and negative cells in colonies grown in cocultures of male and female bone marrow cells.  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