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   26231篇
  免费   2622篇
  国内免费   2098篇
耳鼻咽喉   213篇
儿科学   266篇
妇产科学   368篇
基础医学   3255篇
口腔科学   509篇
临床医学   3577篇
内科学   4031篇
皮肤病学   197篇
神经病学   1517篇
特种医学   981篇
外国民族医学   14篇
外科学   2755篇
综合类   4206篇
现状与发展   8篇
一般理论   4篇
预防医学   1704篇
眼科学   615篇
药学   2885篇
  16篇
中国医学   1590篇
肿瘤学   2240篇
  2024年   324篇
  2023年   436篇
  2022年   1115篇
  2021年   1384篇
  2020年   1064篇
  2019年   933篇
  2018年   892篇
  2017年   904篇
  2016年   778篇
  2015年   1188篇
  2014年   1563篇
  2013年   1316篇
  2012年   1930篇
  2011年   1992篇
  2010年   1308篇
  2009年   999篇
  2008年   1408篇
  2007年   1350篇
  2006年   1276篇
  2005年   1393篇
  2004年   932篇
  2003年   915篇
  2002年   729篇
  2001年   587篇
  2000年   642篇
  1999年   654篇
  1998年   428篇
  1997年   382篇
  1996年   324篇
  1995年   312篇
  1994年   275篇
  1993年   181篇
  1992年   204篇
  1991年   171篇
  1990年   138篇
  1989年   99篇
  1988年   103篇
  1987年   76篇
  1986年   77篇
  1985年   52篇
  1984年   34篇
  1983年   27篇
  1982年   12篇
  1981年   9篇
  1980年   8篇
  1979年   10篇
  1978年   3篇
  1977年   4篇
  1975年   2篇
  1929年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Wu  Jie  Wu  Xiao  Yang  You Qing  Ding  Han  Yang  Le  Bao  You Yuan  Zhou  Lin  Yang  Chen Xing  Hong  Tao 《Neurosurgical review》2022,45(1):139-150

It is controversial whether there is a different risk of recurrence between two histological subtypes in craniopharyngioma (CP) patients. Some reported that adamantinomatous craniopharyngioma (ACP) had a higher risk of recurrence than papillary craniopharyngioma (PCP), but others reported that there is no significant difference between them. So, we conducted this systematic review and meta-analysis to determine the association between the histological subtype of CP and the rate of recurrence. A comprehensive literature search was undertaken in PubMed, EMBASE, and Web of Science for all English articles published up to November 2020. Recurrence data stratified by ACP and PCP were extracted from studies meeting inclusion criteria. A pooled analysis of the association between the histological subtype of craniopharyngioma and rates of recurrence was performed. Thirteen articles containing 974 patients were included. When stratified by two pathological subtypes, the total recurrence rate of ACP was 26.0% and PCP was 14.1%, which showed ACP associated with a higher risk of tumor recurrence than PCP (odds ratio [OR]?=?2.12, 95% confidence interval [CI]?=?1.36, 3.30, P?=?0.00). This is the first meta-analysis focusing on histological subtypes of CP. PCP associates with a lower risk of recurrence than ACP, indicating that ACP could act as one of recurrence risk factors for CP patients. Nevertheless, large sample size and well-designed multicenter studies in which the other clinical variables are controlled to determine the histological subtype of CP as an independent recurrence risk factor are needed.

  相似文献   
72.

Purpose

To evaluate the mechanism for enhancing cell death induced by microwave ablation (MWA) combined with doxorubicin treatment in breast cancer cells.

Materials and methods

Different temperatures of heat treatment were used to mimic the tumor affected by sublethal heat during MWA in vitro. Breast cancer cells were treated at 43 °C and 45 °C, with or without doxorubicin. Cell viability, apoptosis, and intracellular reactive oxygen species (ROS) were evaluated in MDA-MB-231 and SUM-1315 cells. Nude mice breast cancer models were randomly divided into control, MWA, doxorubicin, and combined treatment groups. Tumor apoptosis and DNA damage were evaluated in these groups.

Results

The combined group had lower cell viability than the heat or doxorubicin group (all P < 0.05), and enhanced apoptosis rate was observed in the combined group compared to others (all P < 0.01) in MDA-MB-231 and SUM-1315. Increased capase3 (all P < 0.01) and decreased Bcl-Xl (all P < 0.01) were detected after combined therapy compared to single treated group in vitro. The raisedCaspase3 and DNA damage marker histone H2A.X induced by combined treatment were also approved in the nude mice models. Combined treatment promoted ROS generation compared to doxorubicin or MWA treatment (all P < 0.01). NF-κB expression in the combined group was higher than that of the single treatment group (all P < 0.05). N-acetylcysteine (NAC), a ROS scavenger, partly restrained the combined treatment induced cell proliferation inhibition, Caspase3 and NF-κB compared to doxorubicin treatment (all P < 0.05).

Conclusion

MWA combined with doxorubicin promote cell death via ROS induced cell apoptosis and DNA damage. Increasing ROS has potential for improving the efficiency of combined treatment.  相似文献   
73.
Meng  Xiang-Pan  Tang  Tian-Yu  Ding  Zhi-Min  Wang  Jitao  Lu  Chun-Qiang  Yu  Qian  Xia  Cong  Zhang  Tao  Long  Xueying  Xiao  Wenbo  Wang  Yuan-Cheng  Ju  Shenghong 《Annals of surgical oncology》2022,29(5):2960-2970
Annals of Surgical Oncology - Prediction models with or without radiomic analysis for microvascular invasion (MVI) in hepatocellular carcinoma (HCC) have been reported, but the potential for...  相似文献   
74.
Although Newcastle disease virus (NDV) has a worldwide distribution, some NDV genotypes have more regional geographical ranges within continents. In this study, we isolated a subgenotype XIIb NDV strain, Goose/CH/GD/E115/2017 (E115), from geese in Guangdong province, Southern China, in 2017. Phylogenetic analysis showed that E115 and six other NDVs from geese in China were grouped under subgenotype XIIb and were distinct from subgenotype XIIa, isolated from chickens in South Africa, and subgenotype XIId, isolated from chickens in Vietnam. To better understand the pathogenicity and transmission of the subgenotype XIIb NDVs from geese in Guangdong province, we inoculated chickens and geese with 106 EID50 of the E115 virus. Eight hours after inoculation, three naïve chickens and three naïve geese were co‐housed with the infected chickens or geese to assess intraspecific and interspecific horizontal transmission of the E115 virus. The E115 virus induced significant clinical signs without mortality in chickens, while it was not pathogenic to geese. Intraspecific and interspecific horizontal transmission of the E115 virus was observed among chickens and geese via direct contact. Furthermore, although the current vaccines provided complete protection against disease in chickens after challenging them with the E115 virus, the virus could also be transmitted from vaccinated chickens to naïve contact chickens. Collectively, our findings highlight the need for avoiding the mixing of different bird species to reduce cross‐species transmission and for surveillance of NDV in waterfowl.  相似文献   
75.
Hearts are usually procured from brain‐dead (BD) donors. However, brain death may induce hemodynamic instability, which may contribute to posttransplant graft dysfunction. We hypothesized that BD‐donor heart preservation with a conditioned medium (CM) from mesenchymal stem cells (MSCs) would improve graft function after transplantation. Additionally, we explored the PI3K pathway's potential role. Rat MSCs‐derived CM was used for conservation purposes. Donor rats were either exposed to sham operation or brain death by inflation of a subdural balloon‐catheter for 5.5 hours. Then, the hearts were explanted, stored in cardioplegic solution‐supplemented with either a medium vehicle (BD and sham), CM (BD + CM), or LY294002, an inhibitor of PI3K (BD + CM + LY), and finally transplanted. Systolic performance and relaxation parameters were significantly reduced in BD‐donors compared to sham. After transplantation, systolic and diastolic functions were significantly decreased, terminal deoxynucleotidyl transferase‐mediated dUTP nick end‐labeling (TUNEL)‐positive cells and endonuclease G positive cells were increased in the BD‐group compared to sham. Preservation of BD‐donor hearts with CM resulted in a recovery of systolic graft function (dP/dtmax: BD + CM: 3148 ± 178 vs BD: 2192 ± 94 mm Hg/s at 110 µL, P < .05) and reduced apoptosis. LY294002 partially lowered graft protection afforded by CM in the BD group. Our data suggest that PI3K/Akt pathway is not the primary mechanism of action of CM in improving posttransplant cardiac contractility and preventing caspase‐independent apoptosis.  相似文献   
76.
目的比较急性肾损伤(AKI)2期与AKI 3期连续肾脏替代治疗(CRRT)对危重AKI患者预后的影响。方法以2017年2月至2018年10月在本院ICU实施CRRT的56例危重AKI 2~3期患者为研究对象,按照2012年国际改善全球肾脏病预后组织(KDIGO)制订的新的AKI标准,将患者分为AKI 2期组(26例)与AKI 3期组(30例)。比较两组的预后指标(住院时间、CRRT持续时间、28 d肾功能恢复率、28 d全因病死率)及治疗前后的急性生理学和慢性健康状况Ⅱ(APACEⅡ)评分,采用Kaplan-Meier法对两组进行生存分析。结果AKI 3期组患者的CRRT持续时间[(188.6±112.5)h vs.(96.3±44.7)h]、28 d全因病死率[66.7%(20/30)vs.15.4%(4/26)]均明显高于AKI 2期组(P<0.05),28 d肾功能恢复率[36.7%(11/30)vs.92.3%(24/26)]均明显低于AKI 2期组(P<0.05);治疗后,两组患者APACEⅡ评分均明显降低(P<0.05),AKI 3期组患者的APACEⅡ评分[(23.4±3.6)分vs.(19.8±2.1)分]明显高于AKI 2期组(P<0.05);AKI 3期组患者的生存中位时间(34 d vs.109 d)明显短于AKI 2期组(P<0.05)。结论AKI 2期启动CRRT能够明显降低28 d全因病死率,延长生存中位时间,改善患者的健康状况。  相似文献   
77.
中医学将《伤寒杂病论》所载方剂尊称为经方,古往今来有效指导后世医家治疗外感热病及内伤杂病。虽以现有医疗手段不能将系统性红斑狼疮治愈,但经方在缓解系统性红斑狼疮临床症状、降低糖皮质激素不良反应、防治并发症等方面疗效显著,优势逐渐凸显,值得谨慎辨证分析,深入学习钻研。  相似文献   
78.
The aim of the present study was to investigate the expression and prognostic value of microRNA-135a (miR-135a) and matrix metalloproteinase-13 (MMP-13) in serum of colon cancer (CC). A total of 117 cases of patients admitted to Sheng Li Oil Field Central Hospital from May 2015 to May 2017 were enrolled in the research group (RG), and 120 cases of subjects undergoing normal health examination were included in the control group (CG). The expression of miR-135 and MMP-13 in peripheral blood of the two groups were compared, and their values were analyzed. It was found that miR-135a was decreased and MMP-13 was increased in the RG (P<0.050), both of which were closely related to the pathological features and prognosis of CC (P<0.050), and was also significantly correlated with CEA (P<0.001). ROC curve analysis showed that both of them had great predictive value for the occurrence, prognosis and death of CC. In conclusion, miR-135a was low expressed in CC, while MMP-13 was increased in CC, suggesting that the combined detection of the two had a good diagnostic effect on the occurrence of CC, and was closely related to the prognosis of CCC patients, which might be an excellent potential indicator for the diagnosis and treatment of CC in the future.  相似文献   
79.
80.
目的分析重症坏死性筋膜炎(necrotizing fasciitis,NF)临床特点及诊断治疗要点。方法回顾性分析安徽省儿童医院PICU2007年1月至2013年9月14例NF患儿临床体征、辅助检查、治疗及预后。结果14例患儿中,男8例,女6例,年龄(15.86±10.48)个月,住院天数(29.07±16.30)d,热程(10.64±5.64)d,清创次数(3.07±1.33)次;均有脓毒性休克,5例有多脏器功能衰竭。发病部位:臀部5例,下肢4例,背部2例,会阴部2例,颈部1例;血培养:6例金黄色葡萄球菌(1例耐甲氧西林金黄色葡萄球菌),4例铜绿假单胞菌,3例培养未见明显细菌生长,1例咽峡炎群链球菌。CT均见皮肤及皮下组织水肿,筋膜增厚,11例见软组织气体影。组织活检均确诊为NF;病初表现不典型以局部组织红肿为主,随病情进展患处皮肤苍白伴血疱,后颜色逐渐发紫发黑,部分患儿有皮下握雪感,切开后见筋膜大片苍白坏死;均行切开引流(5例行封闭负压引流持续吸引)、彻底清创、有效抗生素治疗、胶体支持治疗;1期愈合7例(50.00%,7/14),2期植皮4例(28.57%,4/14),死亡3例(21.43%,3/14);随访2年,6例患儿有局部肢体活动受限。结论NF病情危重,常见于会阴部、腹部及四肢,易导致脓毒性休克,多脏器功能衰竭,革兰阴性杆菌感染临床症状极危重,病死率高。NF需尽早确诊,强有力抗生素使用,积极广泛、彻底地外科清创,充分引流,加强支持对症处理可降低病死率。  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