全文获取类型
收费全文 | 40377篇 |
免费 | 2856篇 |
国内免费 | 209篇 |
专业分类
耳鼻咽喉 | 634篇 |
儿科学 | 1031篇 |
妇产科学 | 879篇 |
基础医学 | 5461篇 |
口腔科学 | 737篇 |
临床医学 | 3738篇 |
内科学 | 8560篇 |
皮肤病学 | 650篇 |
神经病学 | 3608篇 |
特种医学 | 1775篇 |
外科学 | 6581篇 |
综合类 | 426篇 |
现状与发展 | 1篇 |
一般理论 | 52篇 |
预防医学 | 2710篇 |
眼科学 | 837篇 |
药学 | 2490篇 |
中国医学 | 206篇 |
肿瘤学 | 3066篇 |
出版年
2023年 | 354篇 |
2022年 | 621篇 |
2021年 | 1730篇 |
2020年 | 871篇 |
2019年 | 1307篇 |
2018年 | 1608篇 |
2017年 | 1115篇 |
2016年 | 1178篇 |
2015年 | 1529篇 |
2014年 | 1949篇 |
2013年 | 2435篇 |
2012年 | 3611篇 |
2011年 | 3471篇 |
2010年 | 1898篇 |
2009年 | 1525篇 |
2008年 | 2294篇 |
2007年 | 2284篇 |
2006年 | 2078篇 |
2005年 | 1869篇 |
2004年 | 1612篇 |
2003年 | 1354篇 |
2002年 | 1165篇 |
2001年 | 542篇 |
2000年 | 467篇 |
1999年 | 405篇 |
1998年 | 242篇 |
1997年 | 182篇 |
1996年 | 177篇 |
1995年 | 161篇 |
1994年 | 124篇 |
1993年 | 126篇 |
1992年 | 229篇 |
1991年 | 204篇 |
1990年 | 197篇 |
1989年 | 206篇 |
1988年 | 172篇 |
1987年 | 160篇 |
1986年 | 143篇 |
1985年 | 145篇 |
1984年 | 127篇 |
1983年 | 112篇 |
1982年 | 117篇 |
1981年 | 90篇 |
1980年 | 79篇 |
1979年 | 95篇 |
1978年 | 102篇 |
1977年 | 59篇 |
1975年 | 55篇 |
1974年 | 61篇 |
1973年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
1.
Patrick W. Keeley Mikayla C. Lebo Jordan D. Vieler Jason J. Kim Ace J. St. John Benjamin E. Reese 《The Journal of neuroscience》2021,41(1):103
Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina. 相似文献
2.
3.
Sung‐Hyun Hwang Myung‐Chul Kim Sumin Ji Yeseul Yang Yeji Jeong Yongbaek Kim 《Cancer science》2019,110(4):1256-1267
Metformin, a drug for type 2 diabetes mellitus, has shown therapeutic effects for various cancers. However, it had no beneficial effects on the survival rate of human malignant mesothelioma (HMM) patients. The present study was performed to elucidate the underlying mechanism of metformin resistance in HMM cells. Glucose‐starved HMM cells had enhanced resistance to metformin, demonstrated by decreased apoptosis and autophagy and increased cell survival. These cells showed abnormalities in mitochondria, such as decreased ATP synthesis, morphological elongation, altered mitochondrial permeability transition pore and hyperpolarization of mitochondrial membrane potential (MMP). Intriguingly, Mdr1 was significantly upregulated in mitochondria but not in cell membrane. The upregulated mitochondrial Mdr1 was reversed by treatment with carbonyl cyanide m‐chlorophenyl hydrazone, an MMP depolarization inducer. Furthermore, apoptosis and autophagy were increased in multidrug resistance protein 1 knockout HMM cells cultured under glucose starvation with metformin treatment. The data suggest that mitochondrial Mdr1 plays a critical role in the chemoresistance to metformin in HMM cells, which could be a potential target for improving its therapeutic efficacy. 相似文献
4.
5.
Autoimmune comorbid diseases associated with lichen planus: a nationwide case–control study 下载免费PDF全文
6.
Jamaal L. Benjamin MD PhD Rebecca Dennis DO Stacy White Jr MD David Munson MD Sudha A. Anupindi MD Maciej Piskunowicz MD Kassa Darge MD PhD Ami Gokli MD Misun Hwang MD 《Journal of ultrasound in medicine》2020,39(5):1031-1036
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates. 相似文献
7.
Feasibility and Diagnostic Potential of Pulmonary Transit Time Measurement by Contrast Echocardiography: A Pilot Study 下载免费PDF全文
8.
Weiyu Ye Anna Olsson-Brown Robert A. Watson Vincent T. F. Cheung Robert D. Morgan Isar Nassiri Rosalin Cooper Chelsea A. Taylor Umair Akbani Oliver Brain Rubeta N. Matin Nicholas Coupe Mark R. Middleton Mark Coles Joseph J. Sacco Miranda J. Payne Benjamin P. Fairfax 《British journal of cancer》2021,124(10):1661
Background Immune checkpoint blockers (ICBs) activate CD8+ T cells, eliciting both anti-cancer activity and immune-related adverse events (irAEs). The relationship of irAEs with baseline parameters and clinical outcome is unclear.Methods Retrospective evaluation of irAEs on survival was performed across primary (N = 144) and secondary (N = 211) independent cohorts of patients with metastatic melanoma receiving single agent (pembrolizumab/nivolumab—sICB) or combination (nivolumab and ipilimumab—cICB) checkpoint blockade. RNA from pre-treatment and post-treatment CD8+ T cells was sequenced and differential gene expression according to irAE development assessed.Results 58.3% of patients developed early irAEs and this was associated with longer progression-free (PFS) and overall survival (OS) across both cohorts (log-rank test, OS: P < 0.0001). Median survival for patients without irAEs was 16.6 months (95% CI: 10.9–33.4) versus not-reached (P = 2.8 × 10−6). Pre-treatment monocyte and neutrophil counts, but not BMI, were additional predictors of clinical outcome. Differential expression of numerous gene pathway members was observed in CD8+ T cells according to irAE development, and patients not developing irAEs demonstrating upregulated CXCR1 pre- and post-treatment.Conclusions Early irAE development post-ICB is associated with favourable survival in MM. Development of irAEs is coupled to expression of numerous gene pathways, suggesting irAE development in-part reflects baseline immune activation.Subject terms: Immunotherapy, Melanoma 相似文献
9.
Marcel Toussaint Raymond J. Gilles Noura Azzabou Benjamin Marty Alexandre Vignaud Andreas Greiser Pierre G. Carlier 《Medicine》2015,94(43)
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis. 相似文献
10.
Comparative outcomes of vascular access in patients older than 70 years with end-stage renal disease
Deokbi Hwang Sujin Park Hyung-Kee Kim Seung Huh 《Journal of vascular surgery》2019,69(4):1196-1206.e5