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   360714篇
  免费   27667篇
  国内免费   9647篇
耳鼻咽喉   3343篇
儿科学   10042篇
妇产科学   5387篇
基础医学   52098篇
口腔科学   8758篇
临床医学   25625篇
内科学   67484篇
皮肤病学   7127篇
神经病学   26153篇
特种医学   11262篇
外国民族医学   68篇
外科学   42692篇
综合类   35364篇
现状与发展   31篇
一般理论   6篇
预防医学   17929篇
眼科学   4797篇
药学   43183篇
  69篇
中国医学   11114篇
肿瘤学   25496篇
  2023年   7271篇
  2022年   9124篇
  2021年   18127篇
  2020年   13817篇
  2019年   19949篇
  2018年   17484篇
  2017年   13012篇
  2016年   9960篇
  2015年   11953篇
  2014年   17767篇
  2013年   18432篇
  2012年   15475篇
  2011年   20866篇
  2010年   15149篇
  2009年   15982篇
  2008年   15326篇
  2007年   13720篇
  2006年   12249篇
  2005年   11210篇
  2004年   9762篇
  2003年   8350篇
  2002年   7326篇
  2001年   6656篇
  2000年   7081篇
  1999年   6911篇
  1998年   6391篇
  1997年   5201篇
  1996年   4159篇
  1995年   3470篇
  1994年   3244篇
  1993年   2602篇
  1992年   2331篇
  1991年   2097篇
  1990年   1895篇
  1989年   1503篇
  1988年   1467篇
  1987年   1150篇
  1985年   3906篇
  1984年   5240篇
  1983年   3865篇
  1982年   3970篇
  1981年   3644篇
  1980年   3172篇
  1979年   2854篇
  1978年   2325篇
  1977年   1983篇
  1976年   2144篇
  1975年   1745篇
  1974年   1482篇
  1973年   1430篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
81.
文题释义: 细胞膜片技术:是在体外接种培养高密度的细胞,使其相互融合生长至100%而形成的透明致密膜状物。该技术不需要胰酶消化即可收集细胞,因此保留了大量的胞外基质、细胞间连接以及细胞-基质连接等结构。目前细胞膜片技术已成为组织工程领域的研究热点,已被推广应用于牙周膜、角膜、心脏、软骨、食管等多种组织器官修复。 成骨细胞:主要由内外骨膜和间充质始祖细胞分化而来,在复杂的骨形成过程中发挥着主要的功能,承担着骨基质的合成、分泌和矿化。骨髓间充质干细胞具有多向分化潜能,能定向分化为成骨细胞,其成骨分化过程可受多种因素的影响,如细胞因子的调控、遗传因素和激素水平等。背景:现阶段骨形态发生蛋白2和碱性成纤维生长因子2对骨髓间充质干细胞膜片增殖、成骨分化的影响和作用机制还尚未可知,如何将生长因子与组织工程细胞膜片技术相整合,最终将其用于骨缺损修复具有重要意义。 目的:探讨单独及联合应用骨形态发生蛋白2和碱性成纤维生长因子2对骨髓间充质干细胞膜片增殖和成骨分化的影响。 方法:体外分离培养鉴定SD大鼠骨髓间充质干细胞并构建细胞膜片,选用不同质量浓度的骨形态发生蛋白2和碱性成纤维生长因子2单独及联合诱导骨髓间充质干细胞膜片,CCK-8法结合碱性磷酸酶活性检测确定2种因子促进膜片增殖和成骨分化的最佳有效质量浓度;然后对骨髓间充质干细胞膜片进行成骨诱导,通过大体及显微镜观察、Vonkossa染色、茜素红染色、RT-PCR检测相关成骨标志物来评估诱导效果。 结果与结论:单独应用骨形态发生蛋白2可增强骨髓间充质干细胞膜片的碱性磷酸酶活性,最佳质量浓度为100 μg/L(P < 0.001),单独应用碱性成纤维生长因子2能加速骨髓间充质干细胞膜片的增殖,最佳质量浓度为20 μg/L(P < 0.001),而联合应用既可以促进膜片增殖又能提高其碱性磷酸酶活性(P < 0.001);经成骨诱导后,4组膜片在形态学上无明显差异,均能诱导骨髓间充质干细胞膜片的成骨分化,其中联合组钙结节最明显(P < 0.001),可显著促进膜片晚期成骨分化并抑制其早期成骨分化,具有明显的协同促进作用(P < 0.001)。结果表明,骨形态发生蛋白2和碱性成纤维生长因子2联合应用时具有协同作用,既可以促进骨髓间充质干细胞膜片增殖,又能显著增强其成骨诱导能力。ORCID: 0000-0003-1918-579X(何惠宇) 中国组织工程研究杂志出版内容重点:干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程  相似文献   
82.
83.
84.
目的:探究归脾丸加减对围绝经期功血患者免疫功能、白细胞介素2(IL-2)、可溶性白细胞介素-2受体(sIL-2R)的影响。方法:选取2019年3月至2018年6月山东省济南市中西医结合医院收治的符合纳入条件的围绝经期功血患者118例作为研究对象,按照就诊顺序编号随机分为对照组和观察组,每组59例。对照组常规西医治疗,观察组加用归脾丸加减治疗,均治疗3个月。观察2组治疗前、完成治疗后T淋巴细胞亚群、IL-2、sIL-2R、凝血功能、子宫内膜厚度、激素水平、症状积分变化;完成治疗后统计治疗过程中的不良反应。结果:1)完成治疗后,2组CD3+、CD4+、CD4+/CD8+、IL-2较治疗前均显著升高,CD8+、sIL-2R则显著下降(P<0.05);完成治疗后观察组CD8+、sIL-2R显著低于于对照组,余均高于对照组(P<0.05)。2)完成治疗后2组凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、子宫内膜厚度较治疗前均显著下降(P<0.05),完成治疗后观察组以上指标均显著低于对照组(P<0.05)。3)完成治疗后2组黄体生成素(LH)、促排卵生成素(FSH)、雌二醇(E2)、孕酮(P)、血管内皮生长因子(VEGF)、碱性成纤维细胞生长因子(bFGF)较治疗前均显著下降(P<0.05),完成治疗后观察组以上指标均显著低于对照组(P<0.05)。4)完成治疗后2组月经周期、阴道出血量、阴道出血天数、神疲乏力积分较治疗前均显著下降(P<0.05),完成治疗后观察组以上指标均显著低于对照组(P<0.05)。5)完成治疗后观察组胃肠道反应、体质量增加、肝功能异常、乳房胀痛发生率均显著低于对照组,2组比较差异有统计学意义(P<0.05)。结论:归脾丸加减能提高围绝经期功血患者免疫功能,抑制IL-2、sIL-2R,改善凝血功能,从而改善症状,提高疗效。  相似文献   
85.
Background: Self sampled HPV testing is a cervical cancer screening method . However, cytology in self-sampled specimen cannot be used as a triage test.  Therefore, other methods for triage should be considered. CyclinA1 (CCNA1) promoter methylation has strong association with cervical precancerous and cancerous lesion. The objective of this study was to compare the diagnostic value of CCNA1 and self-sampled specimen for detecting high-grade cervical intraepithelial lesions or worse (CIN2+). Materials and Methods: A cross sectional study was conducted. Women with abnormal cytology or positive for high risk HPV (hrHPV) indicated for colposcopic examination were enrolled.  Self-collected sampling for hrHPV DNA (SS-HPV) and CCNA1 were performed. hrHPV DNA testing was done by Cobas 4800 method. CCNA1 promoter methylation was detected by CCNA1 duplex methylation specific PCR. Histopathologic result as CIN2+ obtaining from colposcopic directed biopsy or excisional procedure  was considered as positive a gold standard. The results of hrHPV and CCNA1 were reported as positive or negative. Sensitivity specificity, positive predictive value, and negative predictive value of SS-HPV and CCNA1 were calculated by comparing the results with the gold standard. Results: Two hundreds and eighty women were recruited. High-grade cervical lesions and cervical cancer (CIN2+) were diagnosed in 21.8% (61 cases) of the patients. The most common type of hrHPV was non 16, 18 subtype, followed by HPV16 and 18. CCNA1 was positive in 13 patients out of whom, twelve were CIN2+. Sensitivity of CCNA1 was 19.7 % and its  specificity and accuracy were 99.5% and 82.14%, respectively.  The sensitivity of SS-HPV was 70.5%, and its  specificity and accuracy were 39.2% and 43.3%, respectively. Conclusion:  Due to high specificity and positive predictive value of CCNA1, it can be used as alarming sign of having high-grade cervical intraepithelial lesions, especially in patient who has positive hrHPV DNA test based on self-collected sampling.  相似文献   
86.
目的:研究Toll样受体4(TLR4) mRNA及其下游炎性因子肿瘤坏死因子-α(TNF-α)与肝衰竭肠源性内毒素血症(IETM)大鼠肝细胞凋亡的关系,并探索温阳解毒化瘀颗粒对内毒素介导的肝细胞凋亡的调控机制。方法:SPF级雄性SD大鼠85只,随机分为正常组,模型组,TLR4单克隆抗体组和温阳解毒化瘀颗粒组(8.925 g·kg^-1)。采用D-半乳糖胺(D-Gal)腹腔注射建立肝衰竭IETM模型,TLR4单克隆抗体组和温阳解毒化瘀颗粒组在造模前5 d给予温阳解毒化瘀颗粒溶液灌胃,正常组、模型组以等容积蒸馏水代替,直至处死。各组分别在24,48,72 h随机处死大鼠并采集标本。检测24,48,72 h各组时间点血清丙氨酸氨基转移酶(ALT),天门冬氨酸氨基转移酶(AST)水平,苏木素-伊红(HE)染色观察肝组织病理变化,实时荧光定量聚合酶链式反应(Real-time PCR)检测肝组织TLR4 mRNA表达,酶联免疫吸附测定法(ELISA)检测肝组织TNF-α表达,流式细胞仪检测肝细胞凋亡率。结果:与正常组比较,模型组ALT,AST升高,肝组织病理损伤程度明显加重,TLR4mRNA,TNF-α表达均增高(P<0.05,P<0.01),肝细胞凋亡率明显上升(P<0.05,P<0.01);与模型组比较,温阳解毒化瘀颗粒组ALT,AST显著降低(P<0.01),肝组织病理损伤程度明显减轻(P<0.05),TLR4 mRNA,TNF-α表达显著下降(P<0.01),肝细胞凋亡率亦显著降低(P<0.01)。结论:TLR4 mRNA,TNF-α在肝衰竭时与肝细胞凋亡呈正相关,温阳解毒化瘀颗粒能够改善肝衰竭IETM大鼠肝功能,减轻肝细胞损伤,减少肝细胞凋亡,其机制可能与其下调肝脏TLR4 mRNA表达,抑制TNF-α释放,降低肝细胞凋亡率有关。  相似文献   
87.
BackgroundLymph node recurrences (LNR) from colorectal cancer (CRC) still represent a therapeutic challenge, as standardized recommendations have yet to be established. The aim of this study was to analyze short- and long-term oncological outcomes following resection of LNR from CRC.MethodsAll patients with previously resected CRC who underwent histopathologically confirmed LNR resection in 3 tertiary referral centers between 2010 and 2017 were reviewed. Short- and long-term outcomes were analyzed, mainly recurrence-free and overall survival. Further recurrences following LNR resection were also analyzed.ResultsOverall, 18 patients were included. Primary CRC was left-sided in 16 (89%) patients, staged T3-4 in 15 (83%), N+ in 14 (78%) and presented with synchronous metastases in 8 (43%). Median time interval between primary CRC and LNR resections was 31 months. Performed lymphadenectomies were aortocaval (n = 10), pelvic (n = 7), in hepatic pedicle (n = 3) and mesenteric (n = 1). Four patients had associated liver metastases resection. Three (17%) presented with postoperative complications, of which one Clavien-Dindo 3. Fourteen (78%) patients presented with further recurrences after a mean delay of 9 months, with 36% of patients presenting with early (<6 months) recurrence. Five (36%) patients could undergo secondary recurrence resection and 3 (21%) patients radiotherapy. Median overall survival following LNR resection reached 44 months.ConclusionsCurrent results suggest that LNR resection is feasible and associated with improved survival, in selected patients. Longer time interval between primary CRC resection and LNR occurrence appeared to be a favorable prognostic factor whereas multisite recurrence appeared to be associated with impaired long-term survival.  相似文献   
88.
89.
Introduction: Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype associated with an increased risk of recurrence and cancer-related death. Unlike hormone receptor-positive or HER2-positive breast cancers, there are limited targeted therapies available to treat TNBC and cytotoxic chemotherapy remains the mainstay of treatment. Sacituzumab govitecan (IMMU-132) is an antibody-drug conjugate targeting Trop-2 expressing cells and selectively delivering SN-38, an active metabolite of irinotecan.

Areas covered: This review covers the mechanism of action, safety and efficacy of sacituzumab govitecan in patients with previously treated, metastatic TNBC. Additionally, efficacy data in other epithelial malignancies is included based on a PubMed search for ‘sacituzumab govitecan’ and ‘clinical trial’.

Expert opinion: Sacituzumab govitecan has promising anti-cancer activity in patients with metastatic TNBC previously treated with at least two prior lines of systemic therapy based on a single arm Phase I/II clinical trial. A confirmatory Phase III randomized clinical trial is ongoing. Sacituzumab govitecan has a manageable side effect profile, with the most common adverse events being nausea, neutropenia, and diarrhea. The activity of sacituzumab govitecan likely extends beyond TNBC with promising early efficacy data in many other epithelial cancers, including hormone receptor-positive breast cancer.  相似文献   

90.
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