全文获取类型
收费全文 | 68609篇 |
免费 | 4863篇 |
国内免费 | 2296篇 |
专业分类
耳鼻咽喉 | 363篇 |
儿科学 | 1471篇 |
妇产科学 | 830篇 |
基础医学 | 15422篇 |
口腔科学 | 1265篇 |
临床医学 | 5213篇 |
内科学 | 11037篇 |
皮肤病学 | 1621篇 |
神经病学 | 4559篇 |
特种医学 | 967篇 |
外国民族医学 | 15篇 |
外科学 | 5436篇 |
综合类 | 9131篇 |
现状与发展 | 6篇 |
预防医学 | 2922篇 |
眼科学 | 602篇 |
药学 | 7698篇 |
7篇 | |
中国医学 | 1852篇 |
肿瘤学 | 5351篇 |
出版年
2023年 | 584篇 |
2022年 | 1003篇 |
2021年 | 1658篇 |
2020年 | 1465篇 |
2019年 | 2275篇 |
2018年 | 2023篇 |
2017年 | 1868篇 |
2016年 | 1776篇 |
2015年 | 2112篇 |
2014年 | 3350篇 |
2013年 | 3971篇 |
2012年 | 3361篇 |
2011年 | 4360篇 |
2010年 | 3773篇 |
2009年 | 3950篇 |
2008年 | 3680篇 |
2007年 | 3699篇 |
2006年 | 3494篇 |
2005年 | 2982篇 |
2004年 | 2797篇 |
2003年 | 2518篇 |
2002年 | 2033篇 |
2001年 | 1742篇 |
2000年 | 1495篇 |
1999年 | 1385篇 |
1998年 | 1210篇 |
1997年 | 967篇 |
1996年 | 926篇 |
1995年 | 818篇 |
1994年 | 698篇 |
1993年 | 537篇 |
1992年 | 358篇 |
1991年 | 351篇 |
1990年 | 248篇 |
1989年 | 225篇 |
1988年 | 169篇 |
1987年 | 141篇 |
1985年 | 599篇 |
1984年 | 809篇 |
1983年 | 628篇 |
1982年 | 632篇 |
1981年 | 588篇 |
1980年 | 459篇 |
1979年 | 444篇 |
1978年 | 304篇 |
1977年 | 230篇 |
1976年 | 243篇 |
1975年 | 244篇 |
1974年 | 183篇 |
1973年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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
![点击此处可从《Asian Pacific journal of cancer prevention》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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.
《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
3.
4.
《Research in social & administrative pharmacy》2022,18(9):3694-3698
In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area. 相似文献
5.
目的:探索嘌呤能受体X1(purinergic receptor,P2RX1)与肺腺癌(LUAD)患者预后及免疫细胞浸润的相关性。方法:利用生物信息学技术分析非小细胞肺癌中P2RX1的表达及其甲基化与患者预后的关系,对P2RX1共表达基因进行富集分析并筛选核心基因。利用TIMER 2.0数据库、R软件等分析P2RX1与免疫细胞、免疫检查点、免疫基质评分等的相关性。结果:P2RX1在LUAD中表达下调,低表达P2RX1的患者预后较差(P<0.05),且P2RX1与肿瘤纯度、分期等临床病理因素有关(P<0.05)。P2RX1的表达与肺鳞癌患者预后无明显相关。Cg06475633等P2RX1 CpG位点甲基化与患者预后相关。P2RX1共表达基因主要富集于免疫细胞活化、分化等通路和生物学进程,核心基因主要包括BTK、IKZF1等。P2RX1的表达与B细胞浸润、免疫/基质评分、PD-1、CTLA-4等多个免疫检查点显著相关(P<0.05)。结论:P2RX1有望成为LUAD诊断和免疫治疗的新靶点。 相似文献
6.
�� �������������������л �� 《中国实用口腔科杂志》2015,8(11):679-682
??Objective To discuss the influence of basic periodontal therapy on the level of IL-8?? IL-10 in serum and gingival crevicular fluid in patients who have chronic periodontitis complicated by coronary heart disease. Methods A total of 65 cases of patients with chronic periodontitis complicated by coronary heart disease were selected and divided into two groups randomly??Group A of 35 patients who received the basic periodontal therapy and cardiac medical treatment??Group B of 30 patients who received cardiological treatment only. Then??select 25 patient who had developed chronic severe periodontitis with non-systematic disease to establish group C and give them the basic periodontal therapy only. Observe the changes of the IL-8??IL-10 levels in serum and gingival crevicular fluid and the periodontal infection indexes??BI??PD??. Results The results showed that after three months of basic periodontal therapy the periodontal clinical indices of both group A and group C became better and the IL-8 level obviously reduced??while the IL-10 level obviously increased. There was no obvious difference between group A and group B in each examination index before the therapy. After three months??we found that the periodontal infection index??SBI PD??of group A was obviously better than group B. Compared to group B??the IL-8 level of group A obviously reduced??and the IL-10 level obviously increased. The difference was statistically significant??P < 0.05??. Conclusion The basic periodontal therapy can effectively improve periodontal conditions of the patients with chronic periodontal diseases??and reduce the risk of breaking the normal cardiovascular function. 相似文献
7.
8.
《Clinical neurophysiology》2020,131(1):259-264
ObjectivesFasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).MethodsThirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.ResultsThe mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch’s t-test).ConclusionSmall FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.SignificanceClinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS. 相似文献
9.
10.
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