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   1412篇
  免费   91篇
  国内免费   33篇
耳鼻咽喉   5篇
儿科学   15篇
妇产科学   24篇
基础医学   294篇
口腔科学   13篇
临床医学   155篇
内科学   262篇
皮肤病学   20篇
神经病学   55篇
特种医学   26篇
外科学   76篇
综合类   101篇
预防医学   89篇
眼科学   6篇
药学   229篇
中国医学   15篇
肿瘤学   151篇
  2024年   1篇
  2023年   12篇
  2022年   40篇
  2021年   48篇
  2020年   38篇
  2019年   51篇
  2018年   43篇
  2017年   51篇
  2016年   52篇
  2015年   49篇
  2014年   60篇
  2013年   141篇
  2012年   72篇
  2011年   100篇
  2010年   73篇
  2009年   68篇
  2008年   81篇
  2007年   66篇
  2006年   48篇
  2005年   53篇
  2004年   44篇
  2003年   35篇
  2002年   32篇
  2001年   24篇
  2000年   16篇
  1999年   19篇
  1998年   18篇
  1997年   19篇
  1996年   14篇
  1995年   22篇
  1994年   17篇
  1993年   6篇
  1992年   16篇
  1991年   8篇
  1990年   9篇
  1989年   12篇
  1988年   6篇
  1987年   4篇
  1986年   5篇
  1985年   20篇
  1984年   11篇
  1983年   5篇
  1982年   9篇
  1981年   5篇
  1980年   6篇
  1979年   2篇
  1978年   2篇
  1976年   1篇
  1973年   1篇
  1971年   1篇
排序方式: 共有1536条查询结果,搜索用时 15 毫秒
71.
One of the most common sites of extra-thoracic distant metastasis of nonsmall-cell lung cancer is the brain. Our study was performed to discover genes associated with postoperative brain metastasis in operable lung adenocarcinoma (LUAD). RNA seq was performed in specimens of primary LUAD from seven patients with brain metastases and 45 patients without recurrence. Immunohistochemical (IHC) assays of the differentially expressed genes were conducted in 272 surgical-resected LUAD specimens. LASSO Cox regression was used to filter genes related to brain metastasis and construct brain metastasis score (BMS). GSE31210 and GSE50081 were used as validation datasets of the model. Gene Set Enrichment Analysis was performed in patients stratified by risk of brain metastasis in the TCGA database. Through the initial screening, eight genes (CDK1, KPNA2, KIF11, ASPM, CEP55, HJURP, TYMS and TTK) were selected for IHC analyses. The BMS based on protein expression levels of five genes (TYMS, CDK1, HJURP, CEP55 and KIF11) was highly predictive of brain metastasis in our cohort (12-month AUC: 0.791, 36-month AUC: 0.766, 60-month AUC: 0.812). The validation of BMS on overall survival of GSE31210 and GSE50081 also showed excellent predictive value (GSE31210, 12-month AUC: 0.682, 36-month AUC: 0.713, 60-month AUC: 0.762; GSE50081, 12-month AUC: 0.706, 36-month AUC: 0.700, 60-month AUC: 0.724). Further analyses showed high BMS was associated with pathways of cell cycle and DNA repair. A five-gene predictive model exhibits potential clinical utility for the prediction of postoperative brain metastasis and the individual management of patients with LUAD after radical resection.  相似文献   
72.
From the beginning, Drosophila was a high-throughput model organism. Unbiased and genome-wide efforts ranging from Morgan's search for spontaneous mutations and subsequent saturating loss-of-function and gain-of-function screens up to more recent techniques such as microarrays, proteomics and cellular assays have been and will continue to be the backbone of Drosophila research. Integrating these large datasets is one of the next challenges. However, once achieved, a plethora of information far exceeding the information content of the singular experiments will be revealed. Several high-throughput techniques and experimental strategies highlighting the unbiased and integrative nature of Drosophila research during the last century will be discussed.  相似文献   
73.
目的 使用分子线性探针杂交技术结合仪器法液体快速培养分析耐多药( multidrug resistant,MDR)及广泛耐药(extensively drug resistant,XDR)结核分枝杆菌(Mycobacterium tuberculosis,MTB)的耐药基因和表型特征.方法 运用GenoType MTBDR试剂盒检测M/XDR-TB菌株中各耐药基因的突变位点及类型,平行用BD MGIT960系统检测所选菌株对一线及二线抗结核药物的敏感性.结果 (1)94株MDR-TB经MGIT960检测,乙胺丁醇(ethambutol,EMB)、阿米卡星(amikacin,AMK)、氧氟沙星(ofloxacin,OFX)及莫西沙星(moxifloxacin,MFX)的耐药率分别为36.2%、17.0%、54.3%和55.3%.XDR-TB检出率为13.8%.(2)以MGIT960药敏结果作为参考标准,94株MDR-TB中,GenoType MTBDRplus检测MTB对异烟肼(isoniazid,INH)、利福平(rifampin,RFP)耐药的符合率分别为86.2%和95.7%;GenoType MTBDRsl检测MTB对EMB、AMK、OFX及MFX耐药的敏感性分别为47.1%、81.3%、94.1%、94.2%;特异性分别为75.0%、98.7%、90.7%、92.9%.(3)rpoB基因突变中以S531L最多;INH耐药主要由katG基因发生突变导致,以S315T1类型居多;gyrA突变位点主要集中在第94位密码子.所测菌株中有23例为复合耐药,7例为未知突变.结论 M/XDR-TB中,INH、RFP、AMK、OFX及MFX耐药株大多分别是由katG、rpoB、rrs及gyrA突变导致,乙胺丁醇与embB之间的耐药关联性相对较低.GenoType MTBDR试剂盒检测M/XDR-TB敏感性和特异性较好,可以在未获得传统细菌表型药敏结果前指导临床用药治疗.  相似文献   
74.
精子蛋白17抗体免疫磁性颗粒活性分析及细胞成像研究   总被引:1,自引:0,他引:1  
目的:制备精子蛋白17(Sp17)抗体免疫磁性纳米颗粒, 以期用于卵巢癌的磁共振成像靶向诊断.方法:在偶联剂EDC/NHS作用下, 将壳聚糖修饰磁性氧化铁纳米颗粒与抗人Sp17抗体结合, 制备抗Sp17抗体免疫磁性纳米颗粒(IMNPs).透射电镜观察颗粒的形貌特征, 非变性聚丙烯酰胺凝胶电泳评价抗体与磁性颗粒的结合效果, ELISA检测免疫磁性颗粒的免疫活性.将IMNPs与转染人Sp17的卵巢癌HO-8910细胞共孵育, 进行体外磁共振成像检测.结果:成功实现了抗体与磁性纳米颗粒的偶联, 并且IMNPs保持良好的抗体活性.磁共振显示该颗粒成功靶向Sp17阳性的细胞, 没有发生明显的非特异吸附.结论:该免疫磁性纳米颗粒特异性良好, 可进一步用作卵巢癌的靶向治疗研究.  相似文献   
75.
目的探讨血栓弹力图(TEG)在急性一氧化碳中毒(ACOP)患者抗凝治疗中的应用价值。方法选取44例确诊为ACOP的患者作为ACOP组,以及45例健康体检者作为对照组,于治疗前后抽取静脉血,做TEG检测及常规凝血试验,并对检测结果进行统计学分析。结果 ACOP患者的TEG主要检测参数,包括反应时间(R)、血栓形成的速度(由α角度反映)、血栓最大幅度(MA),均高于对照组,差异有统计学意义(P0.01);常规凝血检测的指标,包括凝血酶原时间、活化部分凝血酶原时间、凝血酶时间、纤维蛋白原,两组差异无统计学意义(P0.01)。结论 TEG指标能更敏感地反映ACOP患者的血小板功能活性,为临床治疗提供一定的参考。  相似文献   
76.
目的探讨γ-干扰素(γ-IFN)体外释放试验(IGRA)对诊断结核病的临床价值。方法 479例结核病患者纳入结核病组,42例体检健康者纳入对照组。两组被试均行IGRA、蛋白芯片法检测,采用抗酸染色(AFB)检测结核病患者痰液中的抗酸杆菌。比较IGRA与蛋白芯片法对结核病的诊断效能及在肺结核与肺外结核中的检测效果,并比较IGRA对AFB阳性和阴性的肺结核和肺外结核患者的检测效果。结果IGRA和结核分枝杆菌蛋白芯片法敏感度分别为89.56%(429/479)和76.20%(365/479),特异度分别为100.00%(42/42)和88.10(37/42),准确率分别为90.40%(471/521)和77.16%(402/521)。418例肺结核患者中AFB阳性127例,AFB阴性者291例,其中AFB阳性肺结核患者中IGRA阳性率为93.70%(119/127),AFB阴性肺结核患者阳性率为88.66%(258/291);肺外结核61例患者AFB均阴性,IGRA和结核分枝杆菌蛋白芯片阳性率分别为85.25%(52/61)和68.85%(42/61)。结论 IGRA与结核分枝杆菌蛋白芯片法相比,对结核病诊断有较高的敏感度与特异度,尤其是对AFB阴性的结核病有较高的检出率,值得临床推广应用。  相似文献   
77.

Background

Bioluminescence imaging (BLI) is an ideal tool for noninvasive, quantitative monitoring of tumor progression/regression in animal models. The effectiveness of different treatment strategies is displayed by an altered intensity of bioluminescence, demonstrating a change of the tumor burden. The aim of this study was to establish a reliable, reproducible colorectal hepatic metastases cancer animal model.

Methods

Cells of the human colon carcinoma cell line HCT-116 Lucpos expressing the firefly luciferase enzyme gene were used. HCT-116 Lucpos cells (2.5 × 106) were injected through the portal vein into the liver of immunoincompetent nude mice. BLI was used to analyze intrahepatic tumor burden and growth kinetic.

Results

HCT-116 Lucpos cells demonstrated a progressive and reproducible growth in the liver after intraportal injection. Four days after injection, the animals were analyzed for tumor growth by BLI, and mice without or too low bioluminescence signals were excluded (between 10% and 20% animals). HCT-116 Lucpos intrahepatic tumors responded successfully to different dosages (5 and 10 mg/kg) of 5-fluorouracil.

Conclusions

BLI is an important tool with many potential advantages for investigators. The measurement of intrahepatic tumor growth by imaging luciferase activity noninvasively provides valuable information on tumor burden and effectiveness of therapy. Thus, the presented intrahepatic metastases model based on the growth of HCT-116 Lucpos cells is suitable for in vivo testing of different cancer therapy strategies.  相似文献   
78.
Epithelial Progenitors in the Normal Human Mammary Gland   总被引:8,自引:0,他引:8  
The human mammary gland is organized developmentally as a hierarchy of progenitor cells that become progressively restricted in their proliferative abilities and lineage options. Three types of human mammary epithelial cell progenitors are now identified. The first is thought to be a luminal-restricted progenitor; in vitro under conditions that support both luminal and myoepithelial cell differentiation, this cell produces clones of differentiating daughter cells that are exclusively positive for markers characteristic of luminal cells produced in vivo (i.e., keratins 8/18 and 19, epithelial cell adhesion molecule [EpCAM] and MUC1). The second type is a bipotent progenitor. It is identified by its ability to produce mixed colonies in single cell assays. These colonies contain a central core of cells expressing luminal markers surrounded by cells with a morphology and markers (e.g., keratin 14+) characteristic of myoepithelial cells. Serial passage in vitro of an enriched population of bipotent progenitors promotes the expansion of a third type of progenitor that is thought to be myoepithelial-restricted because it only produces cells with myoepithelial features. Luminal-restricted and bipotent progenitors can prospectively be isolated as distinct subpopulations from freshly dissociated suspensions of normal human mammary cells. Both are distinguished from many other cell types in mammary tissue by their expression of EpCAM and CD49f (6 integrin). They are distinguished from each other by their differential expression of MUC1, which is expressed at much higher levels on the luminal progenitors. To relate the role of these progenitors to the generation of the three-dimensional tubuloalveolar structure of the mammary tree produced in vivo, we propose a model in which the commitment to the luminal versus the myoepithelial lineage may play a determining role in the generation of alveoli and ducts.  相似文献   
79.
【目的】构建小鼠高迁移率族蛋白B1(high-mobility group box 1 protein,HMGB1)启动子全长序列的荧光素酶报告基因用于药物筛选。【方法】采用PCR技术扩增小鼠HMGB1基因启动子全长序列,用GV238载体构建报告质粒GV238-HMGB1-P-Luc,以pGL3-basic作为阴性对照质粒,与内参质粒pRL共转染Hela细胞,以内毒素(LPS,0.2μg/mL)作为激活剂,以正丁酸钠(SB,10 mmol/L)作为抑制剂,分组处理24 h后检测荧光素酶活性。【结果】经酶切、PCR及测序鉴定证实克隆的HMGB1基因启动子全长2 140 bp,DNA序列正确无突变。与pGL3-basic组比较,GV238-HMGB1-P-Luc组荧光素酶活性显著增强(P0.05);与GV238-HMGB1-P-Luc组比较,LPS组荧光素酶活性显著增强(P0.01);与LPS组比较,SB组荧光素酶活性显著降低(P0.01)。【结论】HMGB1基因启动子报告基因构建成功,LPS可以增强其表达,SB则可以抑制LPS刺激下的HMGB1启动子表达增强,可为下一步筛选具有调控HMGB1启动子活性的药物奠定基础。  相似文献   
80.
目的 通过检测经前期综合征(premenstrual syndrome,PMS)肝气逆证模型大鼠大脑皮质和海马γ-氨基丁酸A受体(GABAAR)结合活性变化,探讨中药经前平颗粒对PMS肝气逆证的干预作用。方法 多因素综合刺激法复制PMS肝气逆证大鼠模型。放射性配体受体结合技术测定大鼠皮质和海马GABAAR的结合活性变化。结果 与正常组相比,肝气逆证造模组大鼠大脑皮质和海马GABAAR结合活性均明显增加。与模型组相比,经前平颗粒组大鼠皮质和海马GABAAR活性均明显下降。结论 大鼠皮质和海马GABAAR结合活性增加可能是PMS肝气逆证的重要机制之一。中药经前平颗粒可对GABAAR 结合活性含量异常变化起到调节作用。  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