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   75650篇
  免费   7333篇
  国内免费   5675篇
耳鼻咽喉   558篇
儿科学   812篇
妇产科学   581篇
基础医学   7699篇
口腔科学   1219篇
临床医学   9456篇
内科学   10014篇
皮肤病学   594篇
神经病学   3705篇
特种医学   3024篇
外国民族医学   39篇
外科学   8133篇
综合类   15675篇
现状与发展   14篇
一般理论   16篇
预防医学   6074篇
眼科学   1559篇
药学   8460篇
  82篇
中国医学   5046篇
肿瘤学   5898篇
  2024年   287篇
  2023年   1091篇
  2022年   2818篇
  2021年   3493篇
  2020年   2865篇
  2019年   2250篇
  2018年   2413篇
  2017年   2349篇
  2016年   2126篇
  2015年   3515篇
  2014年   4373篇
  2013年   4365篇
  2012年   6409篇
  2011年   7140篇
  2010年   5009篇
  2009年   4222篇
  2008年   4677篇
  2007年   4627篇
  2006年   4356篇
  2005年   3959篇
  2004年   2774篇
  2003年   2454篇
  2002年   2106篇
  2001年   1624篇
  2000年   1457篇
  1999年   1144篇
  1998年   771篇
  1997年   743篇
  1996年   578篇
  1995年   516篇
  1994年   386篇
  1993年   285篇
  1992年   239篇
  1991年   194篇
  1990年   189篇
  1989年   183篇
  1988年   137篇
  1987年   127篇
  1986年   98篇
  1985年   95篇
  1984年   49篇
  1983年   33篇
  1982年   28篇
  1981年   24篇
  1980年   15篇
  1979年   17篇
  1978年   7篇
  1973年   5篇
  1972年   6篇
  1971年   4篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
11.
本文作者比较了不同时期的纸质病案的使用率,讨论了旧病案的缺点,如难于保存,占用空间及实用价值不大.作者提出了改进保存病案的办法.  相似文献   
12.
王霞芳治疗小儿泄泻的经验   总被引:1,自引:0,他引:1  
小儿泄泻的病因病机因其自身稚阴稚阳的生理特点而较成人为多发,泄泻久甚,易耗伤气液,甚至出现伤阴伤阳的重证、变证。故要重视及时正确地治疗,以防产生危候。王霞芳老师治疗小儿泄泻首先注重审证求因,在精确辨证基础上立法选方而施治,并在病变过程中法随症变,灵活化裁,刻刻护卫脾气胃津,斡旋脾胃气机,重视清浊升降枢机作用。尝用葛根、扁豆衣、荷叶等轻灵升清之品,宣发清阳,泄泻自和。对屡治不愈、迁延日久者,王师认为应辨证细致,选药精到,且又及时而适当地参入止涩药物。固肠止涩法之运用,必须具备苔净,腹软,溲通,无表证和里积等条件,方为合宜。  相似文献   
13.
With the introduction of more potent immunosuppressive agents, rejection has decreased in simultaneous pancreas/kidney transplant (SPK) recipients. However, as a consequence, opportunistic infections have increased. The purpose of this report is to outline the course of SPK patients who developed polyomavirus-associated nephropathy (PVAN). A retrospective review of 146 consecutive SPK recipients from January 1, 1996 to December 31, 2002 was performed. Immunosuppression, rejection and development of PVAN were reviewed. Nine patients were identified. All received induction with either OKT3 or thymoglobulin. Immunosuppression included tacrolimus/cyclosporine, MMF/azathioprine and sirolimus/prednisone. Two patients were treated for kidney rejection prior to the diagnosis of PVAN. Time to diagnosis was an average of 359.3 days post-transplantation. Immunosuppression was decreased but five ultimately lost function. However, none developed pancreatic abnormalities as demonstrated by normal glucose and amylase. Two underwent renal retransplantation after PVAN diagnosis and both have normal kidney function. PVAN was the leading cause of renal loss in SPK patients in the first 2 years after transplantation and is a serious concern for SPK recipients. The pancreas, however, is spared from evidence of infection, and no pancreatic rejection occurred when immunosuppression was decreased.  相似文献   
14.
15.
16.
Bone marrow stromal cells (MSCs) increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis after stroke. Angiopoietin-1 (Ang1) and its receptor Tie2 mediate vascular integrity and angiogenesis as does VEGF and its receptors. In this study, we tested whether MSC treatment of stroke increases Ang1/Tie2 expression, and whether Ang1/Tie2 with VEGF/ vascular endothelial growth factor receptor 2 (VEGFR2) (Flk1), in combination, induced by MSCs enhances angiogenesis and vascular integrity. Male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) and treated with or without MSCs. Marrow stromal cell treatment significantly decreased blood-brain barrier (BBB) leakage and increased Ang1, Tie2, and occludin (a tight junction protein) expression in the ischemic border compared with MCAo control. To further test the mechanisms of MSC-induced angiogenesis and vascular stabilization, cocultures of MSCs with mouse brain endothelial cells (MBECs) or astrocytes were performed. Supernatant derived from MSCs cocultured with MBECs significantly increased MBEC expression of Ang1/Tie2 and Flk1 compared with MBEC alone. Marrow stromal cells cocultured with astrocytes also significantly increased astrocyte VEGF and Ang1/Tie2 expression compared with astrocyte culture alone. Conditioned media from MSCs alone, and media from cocultures of MSCs with astrocytes or MBECs, all significantly increased capillary tube-like formation of MBEC compared with control Dulbecco's modified Eagle's medium media. Inhibition of Flk1 and/or Ang1 significantly decreased MSC-induced MBEC tube formation. Knockdown of Tie2 expression in MBECs significantly inhibited MSC-induced tube formation. Our data indicate MSC treatment of stroke promotes angiogenesis and vascular stabilization, which is at least partially mediated by VEGF/Flk1 and Ang1/Tie2.  相似文献   
17.
Three kinds of lectins (UEA-I, ConA, PNA) were used to study normal, dysplastic, neoplastic nasopharyngeal epithelium by lectin affinitive histochemical method. UEA-I (ulex europeus agglutinin-I) displayed membrane distribution in normal squamous epithelium, but most of nasopharyngeal carcinoma cells were negative. Notably, severe dysplastic epithelium (precancerous lesion) exhibited a strong membranous and cytoplasmic affinity, which contrasted sharply with the normal epithelium and carcinoma cells. The statistically significant difference in the content and distribution of lectin UEA-I in these three groups suggest that UEA-I is a hopeful marker for diagnosing precancerous lesion of the nasopharynx. However, PNA and ConA are of less diagnostic value.
  相似文献   
18.
一种新的正交参数选优法及其在非线性回归分析中的应用   总被引:2,自引:0,他引:2  
非线性回归分析是工程中经常采用的一种用来估计数学模型参数的方法,该方法能否顺利运用与参数初始值的选择有极大关系。本研究提出一种新的正交参数选优法——阻尼正交表法,它不仅可以保证非线性回归分析算法的顺利收敛,而且能够显著提高后者的收敛速度,进而极大改善非线性回归分析算法的应用性能。本研究的数值试验及心肌造影超声心动图定量分析应用实例表明,作为对传统正交参数选优法的一种改进,阻尼正交表法在科学与工程计算或信号与信息处理领域有着很好的应用前景。  相似文献   
19.
20.
Serum interleukin-2 receptor (sIL-2R) level, activities of natural killer cell (NK) and lymphokine activated killer (LAK) cells were determined in 60 patients with advanced carcinoma (AC) before and after treatment with Shenmai Injection (SMI), forty healthy persons were taken as non-carcinoma control (NC). The results showed that: Serum sIL-2R level in AC were much higher than those in NC (P<0.05) and activities of NK and LAK cells in AC were much lower than those in NC (P<0.05) before treatment. There was no significant difference among gastric, colonic and lung cancer (P>0.05). After treatment with SMI, it was found that the level of sIL-2R in all patients were obviously lowered (P<0.05) while the activities of NK and LAK cells were signifficantly higher than that prior the treatment (P<0.05). Relevancy was not found between sIL-2R and NK, LAK cells. These data suggested that the immune function was compromised in AC, and SMI has a wide effect of immuno-regulation.  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