全文获取类型
收费全文 | 32329篇 |
免费 | 2684篇 |
国内免费 | 1075篇 |
专业分类
耳鼻咽喉 | 170篇 |
儿科学 | 644篇 |
妇产科学 | 323篇 |
基础医学 | 9197篇 |
口腔科学 | 511篇 |
临床医学 | 2596篇 |
内科学 | 5573篇 |
皮肤病学 | 1003篇 |
神经病学 | 1096篇 |
特种医学 | 346篇 |
外国民族医学 | 13篇 |
外科学 | 3126篇 |
综合类 | 4145篇 |
现状与发展 | 6篇 |
预防医学 | 1026篇 |
眼科学 | 271篇 |
药学 | 1929篇 |
1篇 | |
中国医学 | 664篇 |
肿瘤学 | 3448篇 |
出版年
2024年 | 33篇 |
2023年 | 310篇 |
2022年 | 412篇 |
2021年 | 927篇 |
2020年 | 755篇 |
2019年 | 964篇 |
2018年 | 923篇 |
2017年 | 894篇 |
2016年 | 923篇 |
2015年 | 1146篇 |
2014年 | 1888篇 |
2013年 | 1957篇 |
2012年 | 1633篇 |
2011年 | 2348篇 |
2010年 | 2004篇 |
2009年 | 2138篇 |
2008年 | 1907篇 |
2007年 | 1949篇 |
2006年 | 1823篇 |
2005年 | 1613篇 |
2004年 | 1460篇 |
2003年 | 1311篇 |
2002年 | 1071篇 |
2001年 | 847篇 |
2000年 | 720篇 |
1999年 | 637篇 |
1998年 | 586篇 |
1997年 | 460篇 |
1996年 | 451篇 |
1995年 | 452篇 |
1994年 | 355篇 |
1993年 | 273篇 |
1992年 | 153篇 |
1991年 | 151篇 |
1990年 | 76篇 |
1989年 | 48篇 |
1988年 | 29篇 |
1987年 | 16篇 |
1985年 | 50篇 |
1984年 | 50篇 |
1983年 | 41篇 |
1982年 | 48篇 |
1981年 | 31篇 |
1980年 | 37篇 |
1979年 | 46篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1976年 | 27篇 |
1975年 | 23篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
Effect of Replacement of Wharton Acellular Jelly With FBS on the Expression of Megakaryocyte Linear Markers in Hematopoietic Stem Cells CD34+ 下载免费PDF全文
zahra Jalili Behnam Emamgolizadeh Hossein Abbaszadeh Shahla JaliliMehdi Derakhshani Mehdi YousefiMehdi TalebiKarim Shams Asenjan Ali Akabr Movassaghpour 《Asian Pacific journal of cancer prevention》2022,23(10):3281-3286
Objective: Animal environments for the growth of stem cells cause the transmission of some diseases and immune problems for the recipient. Accordingly, replacing these environments with healthy environments, at least with human resources, is essential. One of the media that can be used as an alternative to animal serums is Wharton acellular jelly (AWJ). Therefore, in this study, we intend to replace FBS with Wharton jelly and investigate its effect on the expression of megakaryocyte-related genes and markers in stem cells. Materials and Methods: In this study, cord blood-derived CD34 positive HSCs were cultured and expanded in the presence of cytokines including SCF, TPO, and FLT3-L. Then, the culture of expanded CD34 positive HSCs was performed in two groups: 1) IMDM culture medium containing 10% FBS and 100 ng / ml thrombopoietin cytokine 2) IMDM culture medium containing 10% AWJ, 100 ng / ml thrombopoietin cytokine. Finally, CD41 expressing cells were analyzed with the flow cytometry method. The genes related to megakaryocyte lineage including FLI1 and GATA2 were also evaluated using the RT-PCR technique. Results: The expression of CD41, a specific marker of megakaryocyte lineage in culture medium containing Wharton acellular jelly was increased compared to the FBS group. Additionally, the expression of GATA2 and FLI1 genes was significantly increased related to the control group. Conclusion: This study provided evidence of differentiation of CD34 positive hematopoietic stem cells from umbilical cord blood to megakaryocytes in a culture medium containing AWJ. 相似文献
2.
背景:原发性线粒体病具有高度的临床和遗传异质性,其中周围神经是线粒体病的常见受累器官之一。
目的:总结COX20基因变异相关周围神经病的临床表型及遗传学特征。
设计:病例系列报告。
方法:回顾性收集2018年5月至2020年5月复旦大学附属儿科医院诊治的COX20基因变异相关周围神经病患儿的临床资料,总结其临床表现、基因检测结果及治疗效果,并以“COX20”、“线粒体复合物Ⅳ缺乏症(Complex Ⅳ deficiency)”为关键词检索中英文数据库。检索时间均为从建库至2021年12月。总结已报道COX20基因变异与临床表型的关系。
主要结局指标:临床表型和COX20基因变异位点。
结果:4例患儿纳入分析,男、女各2例,其中3例自幼运动发育落后。4例均在儿童期起病,均以行走不稳为首发症状。肌电图均提示多发性周围神经损害改变,感觉神经轴索受累为主。4例患儿均携带COX20基因复合杂合变异,包括错义变异2个,无义变异和移码变异各1个,其中移码变异c.262delG(p.E88Kfs*35)尚未见报道。文献复习目前共报道COX基因变异18个家系22例患儿(包括本文病例),起病中位年龄为5(1.0~17)岁,22例均以行走困难或步态不稳起病,11例(50.0%)有精神运动发育迟滞,病程中14例(63.6%)出现构音障碍,14例(63.6%)出现肌力下降和/或足部畸形,8例(36.4%)出现共济失调,6例(27.3%)出现肌张力障碍,5例(22.7%)存在认知倒退等。21例患儿行神经传导及肌电图检查,19例(90.5%)提示多发性周围神经病变。头颅(18例)及脊髓(10例)MR检查提示,脊髓萎缩4例(40%),小脑萎缩4例(22.2%)。9例患儿已无法独立行走,丧失独立行走能力中位年龄为10(7~21)岁。目前共报道9个变异位点,4种变异类型,其中错义变异5个,剪切变异2个,无义变异和移码变异各1个。
结论:COX20基因变异患者多早期起病,以周围神经系统病变为主要表现,可合并构音障碍、共济失调、肌张力障碍、认知倒退等,病情逐渐进展,致残率高。COX20基因变异类型以错义变异最常见。 相似文献
3.
《Clinical neurophysiology》2021,132(9):2003-2011
ObjectiveA large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS.MethodsA total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis.ResultsPatients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively).ConclusionsThe HFO amplitude in ALS is increased, but does not predict survival.SignificanceThe enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons. 相似文献
4.
5.
Ahmed M. Abu El-Asrar Ajmal Ahmad Eef Allegaert Mohammad Mairaj Siddiquei Priscilla W. Gikandi Gert De Hertogh 《Ocular immunology and inflammation》2020,28(4):575-588
ABSTRACT
Purpose
To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR). 相似文献6.
背景与目的:CD44分子是众多肿瘤细胞的标志分子,其表达水平与肿瘤细胞的恶性程度有关。该研究探讨CD44基因中的单核苷酸多态性(single nucleotide polymorphism,SNP)位点与云南汉族人群宫颈癌和非小细胞肺癌(nonsmall cell lung cancer,NSCLC)易感性的相关性。方法:选取了CD44基因中的两个SNP位点rs13347和rs8193,采用TagMan基因分型的方法,分析这两个多态性位点在497例宫颈癌患者和500例健康对照个体以及483例NSCLC患者和471例健康对照个体中的分布特征,并分析CD44基因中的多态性位点与云南汉族人群宫颈癌和NSCLC的相关性。结果:rs13347和rs8193位点等位基因和基因型在宫颈癌组和对照组中的分布频率的差异无统计学意义(P>0.05)。而在NSCLC组和对照组的比较中:rs13347和rs8193位点等位基因在NSCLC组和对照组中的分布频率的差异有统计学意义(P=0.020和P=0.004);这两个位点基因型在NSCLC组和对照组中分布频率的差异有统计学意义(P=0.027和P=0.020);其中rs13347位点等位基因C在NSCLC组中的分布频率显著高于对照组,可能是NSCLC发生的风险因素(OR=1.250,95% CI:1.035~1.509),rs8193位点等位基因C在对照组中的分布频率显著高于NSCLC组,可能是NSCLC发生的保护性因素(OR=0.768,95%CI:0.641~0.921)。单倍型分析结果显示,rs13347C-rs8193T和rs13347T-rs8193C在NSCLC组和对照组中的分布频率差异有统计学意义(P=0.003和0.022);该结果说明单倍型rs13347C-rs8193T可能是云南汉族人群NSCLC发生的风险性因素(OR=1.316,95%CI:1.096~1.579)。结论:CD44基因中的两个SNP位点rs13347和rs8193可能与云南汉族人群宫颈癌发病风险无关,而可能与云南汉族人群NSCLC具有相关性。 相似文献
7.
8.
Cis-diamminedichloridoplatinum(II)(CDDP)-based combination chemotherapy is frequently used in gastrointestinal cancer. The synergistic mechanism of all-trans retinoic acid (ATRA), cisplatin (CDDP) and 5-fluorouracil (5-FU) in combination remains unclear. Despite their potent antitumor properties, resistance to CDDP and 5-FU develops frequently in tumors. To clarify this mechanism, we determined the sensitivity to each drug and their combination in two gastrointestinal cancer stem cells (CSCs) subpopulation.Here, we report the identification and separation of CD44+ cells from human gastric carcinoma (AGS) and human esophageal squamous cell carcinoma (KYSE-30) cancer cell lines by magnetic activated cell sorting (MACS). We allowed the CD44± cells to grow 6 days at a subtoxic concentration of ATRA and then treated with different concentration of CDDP and 5-FU for 24 h. The cytotoxicity was examined by cell proliferation MTT assay. Additionally, AO/EB staining was used for detection of apoptotic cells. In order to determine whether the growth inhibition was also associated with changes in cell cycle distribution, cell cycle analysis was performed using flow cytometry.Low concentration of ATRA (1 μM, 6days) followed by 5-FU and CDDP was found to be more effective than either drugs alone, thus resulting in synergistic cytotoxicity in Kyse-30 and AGSCD44± cells. Furthermore, there was an indication that the combination of ATRA with 5FU and CDDP caused an increase in cell cycle arrest in G2/M and G0/G1.We conclude that low concentration of ATRA enhances the cytotoxicity of CDDP and 5FU by facilitating apoptosis and cell cycle arrest in gastrointestinal CSCs and provide a rational basis for the design of novel, well-tolerated CDDP- and 5FU-based chemotherapy in human gastrointestinal carcinoma. 相似文献
9.
目的探讨对先天性耳甲腔型小耳畸形患者行全扩张法全耳再造术后,利用残耳皮瓣改善再造耳颅耳沟的效果。方法回顾分析 2012 年 1 月—2017 年 1 月收治的 150 例先天性耳甲腔型小耳畸形患者。其中男 92 例,女 58 例;年龄 6.5~35.0 岁,平均 11.1 岁。采用一期扩张器埋置、二期全扩张法全耳再造术后发现上部颅耳沟浅显;于 6~12 个月后行三期再造耳修整。将残耳垂通过“Z”字改型转移以再造耳垂。在残耳上部作蒂在轮屏切迹的残耳上部皮瓣,弧形切开松解并加深上部颅耳沟,将上部残耳皮瓣向颅耳沟创面旋转推进缝合以覆盖创面;将带皮下组织蒂的残耳软骨组织瓣插入支架底部形成的腔隙内,并缝合固定,以增加支架的高度;耳甲腔区其余残耳皮瓣用以覆盖耳甲腔创面。结果术后拆线时 1 例患儿皮瓣远端出现直径约 0.5 cm 的表皮水疱,经换药 2 周后愈合;其余患者皮瓣成活良好。患者均获随访,随访时间 6~12 个月,平均 9.6 个月。再造耳上部颅耳沟均明显加深,再造耳支架高度不同程度增加,双耳对称性佳,耳甲腔无明显挛缩变小,再造耳外观满意。再造耳上部表面毛发明显减少,耳周发际线上移。结论采用耳甲腔型小耳畸形的残耳皮瓣及残耳软骨瓣转移,不仅可加深颅耳沟,而且可增加上部支架的高度,术后颅耳沟变形较轻,再造耳与正常耳廓的对称性更佳。 相似文献
10.