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   2053篇
  免费   250篇
  国内免费   112篇
耳鼻咽喉   10篇
儿科学   29篇
妇产科学   63篇
基础医学   344篇
口腔科学   65篇
临床医学   122篇
内科学   297篇
皮肤病学   22篇
神经病学   167篇
特种医学   47篇
外科学   226篇
综合类   216篇
预防医学   191篇
眼科学   20篇
药学   214篇
中国医学   27篇
肿瘤学   355篇
  2024年   9篇
  2023年   39篇
  2022年   115篇
  2021年   160篇
  2020年   115篇
  2019年   126篇
  2018年   87篇
  2017年   99篇
  2016年   111篇
  2015年   107篇
  2014年   162篇
  2013年   158篇
  2012年   125篇
  2011年   132篇
  2010年   95篇
  2009年   111篇
  2008年   122篇
  2007年   103篇
  2006年   92篇
  2005年   61篇
  2004年   36篇
  2003年   16篇
  2002年   26篇
  2001年   21篇
  2000年   23篇
  1999年   15篇
  1998年   17篇
  1997年   15篇
  1996年   17篇
  1995年   12篇
  1994年   10篇
  1993年   9篇
  1992年   5篇
  1991年   8篇
  1990年   6篇
  1988年   6篇
  1987年   3篇
  1986年   3篇
  1985年   5篇
  1984年   7篇
  1981年   3篇
  1980年   3篇
  1978年   2篇
  1977年   3篇
  1975年   2篇
  1973年   2篇
  1972年   3篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
排序方式: 共有2415条查询结果,搜索用时 218 毫秒
61.
目的探讨环状RNA PUM1(circPUM1)对结肠癌细胞增殖、凋亡、迁移、侵袭的影响及其分子机制。方法实时荧光定量聚合酶链反应(qRT-PCR)检测结肠癌组织、癌旁组织中circPUM1、微小RNA-524-5p(miR-524-5p)的表达量。体外培养人结肠癌细胞株SW620,分别将si-NC、si-circPUM1、miR-NC、miR-524-5p mimics、si-circPUM1与anti-miR-NC、si-circPUM1与anti-miR-524-5p转染至SW620细胞。甲基噻唑基四唑(MTT)检测细胞增殖;Transwell小室实验检测细胞迁移、侵袭能力;流式细胞术检测细胞凋亡率;双荧光素酶报告实验验证circPUM1是否能够结合miR-524-5p;蛋白免疫印迹法(Western blotting)检测细胞周期蛋白1(Cyclin D1)、p21、基质金属蛋白酶-2(MMP-2)、基质金属蛋白酶-9(MMP-9)、B淋巴细胞瘤-2(Bcl-2)、B淋巴细胞瘤-2相关蛋白(Bax)表达量。结果结肠癌组织circPUM1的表达水平显著高于癌旁组织(P<0.05),miR-524-5p的表达水平显著降低(P<0.05);干扰circPUM1表达或miR-524-5p过表达后,细胞活力显著降低(P<0.05),迁移细胞数与侵袭细胞数显著减少(P<0.05),细胞凋亡率显著升高(P<0.05),Cyclin D1、MMP-2、MMP-9、Bcl-2蛋白表达显著降低(P<0.05),p21、Bax蛋白表达显著升高(P<0.05);双荧光素酶报告实验证实circPUM1可靶向结合miR-524-5p的作用位点;抑制miR-524-5p表达可减弱干扰circPUM1表达对SW620细胞增殖、凋亡、迁移、侵袭的作用。结论circPUM1可通过海绵吸附miR-524-5p促进结肠癌细胞增殖、迁移、侵袭,抑制细胞凋亡。  相似文献   
62.
Endogenous plasma prolactin and baseline corticosterone concentrations were measured in Dark-eyed Juncos (Junco hyemalis, n=27) photostimulated into migratory condition to look at how these hormones may be linked to the development of migratory condition. In addition to the commonly used assay for corticosterone, a recombinant-derived European starling prolactin assay validated for Dark-eyed juncos was used to measure endogenous prolactin in order to detect small but significant changes in plasma prolactin levels. In response to transfer from short (10.5L:13.5D) to long (18L:6D) days, the birds increased in body mass, fat score, daily food intake, and nocturnal migratory locomotor activity (Zugunruhe). On short-days, both hormones were low (corticosterone mean=2.89ng/mL+/-0.48 SE; prolactin mean=6.43ng/mL+/-1.31 SE). But, within 14 days of photostimulation both hormones increased significantly (Day 14: corticosterone mean=5.71ng/mL+/-0.77 SE; prolactin mean=19.67ng/mL+/-2.81 SE), rising further by Day 48 (corticosterone mean=8.41ng/mL+/-0.72; prolactin mean=112.67ng/mL+/-9.18 SE). On Day 48, birds with the most fat (fat score=3) had significantly higher corticosterone levels than those with less fat (fat score=2). This pattern, albeit not statistically significant, was similar for prolactin. These results illustrate that, independent of the seasonal peak in prolactin associated with the onset of photorefractoriness, plasma prolactin levels can rise, in concert with corticosterone, as birds come into spring migratory condition, providing some support for earlier hypotheses that these two hormones play an integral role in the development of migratory condition. Whether similar changes in plasma prolactin occur with respect to autumn migration, as does baseline corticosterone, has yet to be determined.  相似文献   
63.
目的观察白藜芦醇(Resveratrol,Res)对人结肠癌细胞HCT-8上皮间-质转化(EMT)的影响,初步探讨其可能存在的机制。方法取对数生长期的人结肠癌HCT-8细胞,采用不同浓度的白藜芦醇(0、40、80、120μmol/L)对细胞分别进行干预24、48、72 h;MTT法检测不同时间Res对HCT-8细胞增殖活性的影响;细胞黏附试验检测Res对HCT-8细胞黏附能力的影响;Transwell小室试验检测Res对HCT-8细胞迁移和侵袭能力的影响;进一步采用蛋白免疫印迹法和qRT-PCR分别检测Res对HCT-8细胞中蛋白激酶B(AKT)、磷酸化蛋白激酶B(P-AKT)、E-钙黏蛋白(E-cadherin)、N-钙黏蛋白(N-cadherin)、波形蛋白(Vimentin)和mRNA表达的影响。结果 Res(浓度为40、80、120μmol/L)在干预后24、48、72 h均可以明显抑制HCT-8细胞的增殖活性(P<0.05)。与空白对照组相比,细胞的同种黏附能力增强,异种黏附能力降低,差异有统计学意义(P<0.05)。与空白对照组相比,Res 120μmol/L对细胞迁移和侵袭能力均具有明显的抑制作用(P<0.05),Res 120μmol/L作用HCT-8细胞48 h后,HCT-8细胞中上皮间质标志性蛋白E-钙黏蛋白(E-cadherin)和mRNA的相对表达量增加(P<0.05),而AKT蛋白的表达无明显变化(P>0.05),P-AKT蛋白的表达明显减少(P<0.05);N-钙黏蛋白(N-cadherin)、波形蛋白(Vimentin)和mRNA的相对表达量显著减少,差异有统计学意义(P<0.05)。结论白藜芦醇通过调控细胞EMT抑制人结肠癌HCT-8细胞的迁移和侵袭能力,其作用机制可能受PI3K/AKT信号通路的调控。  相似文献   
64.
目的 探讨长链非编码RNA-癌基因SEI1-1(lnc-SERTAD1-1)对结直肠癌增殖、迁移及预后的影响。方法 选取125例结直肠癌患者的标本,检测癌组织和癌旁正常组织中lnc-SERTAD1-1的表达水平,分析lnc-SERTAD1-1与临床病理特征的相关性,分析lnc-SERTAD1-1对结直肠癌预后的影响。检测正常人结肠组织细胞CCD-18Co与人结直肠癌细胞HCT15中lnc-SERTAD1-1的表达。慢病毒转染构建含有目的基因lnc-SERTAD1-1过表达的HCT15(HO)及含有空白载体质粒的HCT15(HOC),检测其lnc-SERTAD1-1以及SERTAD1蛋白的表达,并检测lnc-SERTAD1-1对结直肠癌细胞增殖和迁移能力的影响。结果 与癌旁正常组织比较,lnc-SERTAD1-1在结直肠癌组织(0.002 198±0.000 499 vs. 0.002 998±0.000 392,P < 0.001)和癌细胞(0.000 123±0.000 010 vs. 0.000 182±0.000 012,P = 0.004)中呈低表达水平 ;其表达高低与结直肠癌患者的肿瘤部位、肿瘤大小及肿瘤的大体分型相关(P均< 0.05)。在125例结直肠癌患者中,lnc-SERTAD1-1高表达(≥0.000 970)是其术后总生存及无病生存的独立保护因素(总生存HR = 0.228,95% CI:0.107 ~ 0.485,P < 0.001;无病生存HR = 0.228,95% CI:0.103 ~ 0.506,P < 0.001)。体外实验显示lnc-SERTAD1-1表达上调能抑制结直肠癌细胞的增殖和迁移(P均< 0.05)。结论 lnc-SERTAD1-1通过抑制结直肠癌细胞的增殖和迁移发挥抑癌基因的作用,是结直肠癌重要的预后影响因素。  相似文献   
65.
66.
67.
Background and Aim: The migration of mesenchymal cells to areas of mucosal or submucosal tissue damage is an essential factor for wound healing in the intestine. Thus far, neither migration inducing factors nor signal transduction cascades involved in the migration of colonic myofibroblasts (CMF) have been studied in detail. Methods: Primary CMF were isolated from the mucosa of surgical specimens or endoscopic biopsies. Migration assays of CMF were performed in the modified 48-well Boyden chamber. Secreted growth factors were quantified by ELISA. Results: CMF secrete autocrine or paracrine migration stimulating factors. Culture supernatant of CMF collected after 24, 48, and 72 h (=conditioned media) stimulated the migration of CMF ( 48.9 &#45 4.5; 60.3 &#45 5.3 and 67.8 &#45 6.4 cells/hpf, respectively). Heating of conditioned media to 95°C or addition of cycloheximide during the conditioning period abolished migration. Addition of PDGF-AB (2.5-50 ng/ml) or IGF-I (10-300 ng/ml) to CMF conditioned media further increased the migration of CMF to a maximum of 177 and 160%, respectively, when compared to the migration induced by conditioned medium alone. Addition of EGF (2.5-50 ng/ml) or TGF- &#103 1 (1-50 pg/ml) caused an increased CMF migration up to 139 and 128%, respectively. MCP-1 (5-50 ng/ml) and bFGF (10-200 ng/ml) had no effect on CMF migration. Conclusion: The growth factors PDGF-AB, IGF-I, EGF and TGF- &#103 1 stimulate the migration of CMF. However, factors secreted by CMF are essential for their ability to migrate in response to these growth factors. The identification of physiologically relevant migration inducing factors may help to elucidate the network of interactions and the complex mechanisms involved in intestinal wound healing or fibrosis.  相似文献   
68.
69.
《Acta histochemica》2021,123(7):151776
ObjectiveThis work aims to determine the role of circular RNA (circRNA) AGFG1 and related molecular mechanism in esophageal squamous cell carcinoma (ESCC) cells.MethodsCircAGFG1 expression in ESCC cell lines was probed with qRT-PCR. ESCC cells were transfected/cotransfected with si-circAGFG1, pcDNA3.1-circAGFG1, si-Microtubule Associated Protein RP/EB Family Member 2 (MAPRE2), pcDNA3.1-circAGFG1 + miR-4306 mimic or pcDNA3.1-circAGFG1 + si-MAPRE2. The interactions between circAGFG1 and miR-4306 as well as miR-4306 and MAPRE2 were confirmed by dual-luciferase reporter assay. Cell proliferation, migration and invasion were detected by CCK-8, cell scratch and Transwell assays, respectively. Relative RNA expression levels of circAGFG1, miR-4306 and MAPRE2 in ESCC cells were measured by qRT-PCR. The protein level of MAPRE2 in ESCC cells was monitored by Western blot.ResultsCircAGFG1 was observably upregulated in ESCC cell lines. Besides, circAGFG1 silencing hindered ESCC cell development in vitro, and these effects were enhanced by miR-4306 overexpression or MAPRE2 silencing. Mechanistic analysis evidenced that circAGFG1 might act as a competitive endogenous RNA of miR-4306 to relieve the repressive effect of miR-4306 on its target MAPRE2.ConclusionCircAGFG1 facilitates ESCC progression via the miR-4306/MAPRE2 axis, and it may act as a possible biomarker for therapy and diagnosis in ESCC treatment.  相似文献   
70.
Osteosarcoma is a highly malignant tumor that occurs in the bone. Previous studies have shown that multiple microRNAs (miRNAs) regulate the development of osteosarcoma. This study aimed to explore the role of miR-629-5p and its target gene, caveolin 1 (CAV1), in osteosarcoma development. To analyze the expression of miR-629-5p and CAV1 mRNA in osteosarcoma tissues and cell lines, qRT-PCR analysis was performed. Dual-luciferase reporter experiments were subsequently performed to validate the relationship between CAV1 and miR-629-5p. CCK8 assay was used to measure osteosarcoma cell proliferation, and wound-healing assay was performed to study their migratory phenotype. Our findings revealed that miR-629-5p was overexpressed in osteosarcoma tissues and cells, and thereby enhanced cell proliferation and migration. Further, we validated that miR-629-5p targets CAV1 mRNA directly. CAV1 expression, which was negatively correlated with miR-629-5p expression, was found to be downregulated in osteosarcoma tissue samples. Moreover, our data showed that an increase in CAV1 level led to a decline in osteosarcoma cell proliferation and migration, which could be rescued by miR-629-5p upregulation. Overall, our study confirmed that miR-629-5p promoted osteosarcoma proliferation and migration by directly inhibiting CAV1.  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