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   157032篇
  免费   15306篇
  国内免费   12023篇
耳鼻咽喉   1388篇
儿科学   1551篇
妇产科学   1715篇
基础医学   17841篇
口腔科学   2623篇
临床医学   20878篇
内科学   22746篇
皮肤病学   1636篇
神经病学   7846篇
特种医学   5782篇
外国民族医学   92篇
外科学   15919篇
综合类   28987篇
现状与发展   55篇
一般理论   11篇
预防医学   11614篇
眼科学   4227篇
药学   16686篇
  143篇
中国医学   9728篇
肿瘤学   12893篇
  2024年   560篇
  2023年   2472篇
  2022年   6367篇
  2021年   8195篇
  2020年   6193篇
  2019年   5268篇
  2018年   5454篇
  2017年   5069篇
  2016年   4728篇
  2015年   7213篇
  2014年   8870篇
  2013年   8149篇
  2012年   11604篇
  2011年   12597篇
  2010年   8353篇
  2009年   6735篇
  2008年   8328篇
  2007年   8300篇
  2006年   7927篇
  2005年   7836篇
  2004年   5562篇
  2003年   5477篇
  2002年   4680篇
  2001年   4005篇
  2000年   3727篇
  1999年   3733篇
  1998年   2416篇
  1997年   2430篇
  1996年   1809篇
  1995年   1730篇
  1994年   1502篇
  1993年   940篇
  1992年   1146篇
  1991年   941篇
  1990年   780篇
  1989年   720篇
  1988年   590篇
  1987年   517篇
  1986年   455篇
  1985年   346篇
  1984年   158篇
  1983年   141篇
  1982年   80篇
  1981年   85篇
  1980年   51篇
  1979年   66篇
  1977年   10篇
  1976年   7篇
  1974年   8篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
目的 探讨急性胆囊炎行腹腔镜胆囊切除术的手术时机,并总结操作技巧。方法 回顾性分析2000年6月~2005年6月265例腹腔镜胆囊切除术治疗急性胆囊炎的临床资料。结果 265例中手术成功244例,成功率92.1%。中转开腹21例,其中小于72小时(Ⅰ组),超过72小时(Ⅱ组)的中转率分别为3.1%(4/129),12.5%(17/136)。Ⅰ组与Ⅱ组比较成功率无明显差别(P〉0.05)。全组无死亡病例,也无严重并发症发生。结论 急性胆囊炎行腹腔镜胆囊切除术安全可行,只要无内科禁忌证,应积极开展腹腔镜手术。  相似文献   
42.
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   
43.
SUMMARY: It is desirable to estimate epileptogenic zones with both location and extent information from noninvasive EEG. In the present study, the authors use a subspace source localization method (FINE), combined with a local thresholding technique, to achieve such tasks. The performance of this method was evaluated in interictal spikes from three pediatric patients with medically intractable partial epilepsy. The thresholded subspace correlation, which is obtained from FINE scanning, is a favorable marker, which implies the extents of current sources associated with epileptic activities. The findings were validated by comparing the results with invasive electrocorticographic (ECoG) recordings of interictal spike activity. The surgical resections in these three patients correlated well with the epileptogenic zones identified from both EEG sources and ECoG potential distributions. The value of the proposed noninvasive technique for estimating epileptiform activity was supported by satisfactory surgery outcomes.  相似文献   
44.
Brain tumors are increasingly prevalent. Recent advances focus attention on individual, disseminated tumor cells that cannot be imaged or eliminated. Cells of the immune system may be ideally suited to attack individual tumor cells, but more basic understanding is needed. We describe a rat model, using the lacZ reporter gene, that allows identification of individual tumor cells, and tumor-leukocyte interactions in vivo. The model demonstrates how widely tumor can disseminate, without secondary tumorigenesis or recruitment of nonneoplastic cells. It demonstrates that leukocytes have access to disseminating tumor. Among its many applications, this work lays a foundation for developing cell-mediated immunotherapy against individual brain tumor cells.  相似文献   
45.
The present study was designed to detect three single nucleotide polymorphisms (SNPs) located on 22q11 that was thought as being of particularly importance for genetic research into schizophrenia. We recruited a total of 176 Chinese family trios of Han descent, consisting of mothers, fathers and affected offspring with schizophrenia for the genetic analysis. The transmission disequilibrium test (TDT) showed that of three SNPs, rs10314 in the 3'-untranslated region of the CLDN5 locus was associated with schizophrenia (chi(2) = 4.75, P = 0.029). The other two SNPs, rs1548359 present in the CDC45L locus centromeric of rs10314 and rs739371 in the 5'-flanking region of the CLDN5 locus, did not show such an association. The global chi-square (chi(2)) test showed that the 3-SNP haplotype system was not associated with schizophrenia although the 1-df test for individual haplotypes showed that the rs1548359(C)-rs10314(G)-rs739371(C) haplotype was excessively non-transmitted (chi(2) = 5.32, P = 0.02). Because the claudin proteins are a major component for barrier-forming tight junctions that could play a crucial role in response to changing natural, physiological and pathological conditions, the CLDN5 association with schizophrenia may be an important clue leading to look into a meeting point of genetic and environmental factors.  相似文献   
46.
目的探讨肘、膝、踝关节内外翻畸形的治疗方式。方法对55例8~16岁的关节内、外翻畸形患儿(肘关节30例,膝15例,踝10例),采用肘外侧切口,踝、膝内外侧切口,截骨矫形,1枚或2枚“∩”形钉内崮定治疗,术后石膏托外固定4周,结果随访50例,随访时间3~24个月,截骨均达到骨性愈合,无一例发生感染,内固定松动临床疗效优48例(96%),良2例(4%)。结论用“∩”形钉作为截骨矫形内固定材料.具有操作简单、损伤小、效果好的优点。  相似文献   
47.
CT增强扫描在评价NSCLC血管生成中的临床意义   总被引:3,自引:3,他引:0  
目的 探讨非小细胞肺癌 (NSCLC)血管内皮生长因子 (VEGF)的表达水平与CT增强程度的关系 ,从影像学角度评价肿瘤血管生成在肺癌诊断、治疗及淋巴结转移中的临床价值。方法 对 30例NSCLC病人进行动态螺旋CT扫描 (SCT) ,测量病灶增强幅度 ,并利用免疫组化技术检测VEGF。对病灶增强值、VEGF阳性表达及淋巴结转移情况进行统计学分析。结果  30例肺癌病人CT增强值均数为 (36 .2 8± 6 .41 )HU ,VEGF阳性表达 2 1例 ,阴性表达 9例。VEGF在中晚期的阳性表达高于早期病人 (Ρ<0 .0 5) ,淋巴结转移组高于非淋巴结转移组 (Ρ <0 .0 5) ;癌灶增强值与VEGF阳性表达、肿瘤分期及淋巴结转移亦呈正相关。结论 NSCLC的CT增强程度能够反映肿瘤的血管生成 ,并与淋巴结转移密切相关 ,有助于肺癌的诊断、TNM分期 ,而且可以从肿瘤分子生物学行为方面补充目前肺癌分期方法的不足  相似文献   
48.
H N Xu 《中华外科杂志》1992,30(11):680-1, 700
21 cases of posterior urethral rupture due to pelvic fracture were treated by acute interlocking sound urethroplasty since 1982. Postoperative pericatheter urethrography was carried out to observe the recover of urethral rupture. The results showed that the time for recover of ruptured urethra varied from 4 to 13 weeks. 71% of all cases required more than 8 weeks for recovery. The patients were followed up from 1 to 9 years, and 86% of them showed satisfactory results. It is believed that pericatheter urethrography not only provides an objective proof for the recovery of ruptured urethra but also can be used as a reliable basis for the removal of stenting catheter.  相似文献   
49.
短暂性脑缺血发作患者血浆中TXB2和PGF1α含量检测   总被引:3,自引:0,他引:3  
本文用放射免疫法测定47例短暂性脑缺血发作(TIA)患者血浆中血栓素B_2(TXB_2)和6酮-前列腺F_(1α)(PGF_(1α))的含量。结果发现TIA患者血浆中TXB_2含量增高,PGF_(1α)降低;头颅CT或MRI示有小灶性梗塞者及TIA发作持续时间长于30min者TXB_2升高和PGF_(1α)降低更显著。治疗3个月后,血浆PGF_(1α)显著增高。TXB_2和PGF_(1α)在体内的失平衡是急性脑血管疾病发病的重要机理之一。  相似文献   
50.
为了探讨精神分裂症患者治疗期间多巴胺的变化,我们选择舒必利治疗组20例,非舒必利治疗组10例作为病例组;15例非精神病患者作为对照组;检测脑脊液中多巴胺代谢产物高香草酸的含量;结果显示两组无显著性差异。精神分裂症患者治疗后舒必利组高香草酸含量升高,非舒必利组则降低,进一步分析显示舒必利治疗组非显效者较显效者治疗后高香草酸显著升高。提示机体对药物阻滞多巴胺受体后代偿反应的强弱与疗效有一定关系。  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