全文获取类型
收费全文 | 2172篇 |
免费 | 94篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 69篇 |
儿科学 | 98篇 |
妇产科学 | 107篇 |
基础医学 | 168篇 |
口腔科学 | 147篇 |
临床医学 | 108篇 |
内科学 | 419篇 |
皮肤病学 | 65篇 |
神经病学 | 103篇 |
特种医学 | 127篇 |
外国民族医学 | 1篇 |
外科学 | 405篇 |
综合类 | 33篇 |
预防医学 | 57篇 |
眼科学 | 112篇 |
药学 | 160篇 |
中国医学 | 12篇 |
肿瘤学 | 79篇 |
出版年
2023年 | 19篇 |
2022年 | 31篇 |
2021年 | 54篇 |
2020年 | 43篇 |
2019年 | 51篇 |
2018年 | 78篇 |
2017年 | 70篇 |
2016年 | 59篇 |
2015年 | 72篇 |
2014年 | 84篇 |
2013年 | 106篇 |
2012年 | 171篇 |
2011年 | 182篇 |
2010年 | 104篇 |
2009年 | 78篇 |
2008年 | 113篇 |
2007年 | 177篇 |
2006年 | 141篇 |
2005年 | 155篇 |
2004年 | 118篇 |
2003年 | 107篇 |
2002年 | 93篇 |
2001年 | 18篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 4篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1969年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有2270条查询结果,搜索用时 0 毫秒
51.
Wassef Amr Mohamed Abdelaziz Abdelhakim Mohamad Amr Salah Eddin Macky Tamer Ahmed Raafat Karim Adly Youssef Maha Mohamed 《International ophthalmology》2021,41(12):4163-4174
International Ophthalmology - To investigate the retinal microvascular and choroidal thickness changes in eyes with active Beh?et’s disease posterior uveitis and post-remission. A... 相似文献
52.
Background: The aim of this study is to evaluate CD4+, CD8+, and CD45RO+ T cells, and vascular endothelial growth factor (VEGF) expression in cyclosporin A (CsA)–induced rat overgrown gingival tissue during an 8‐week period. Methods: Sixty male Sprague‐Dawley rats weighing 200 to 250 g were used in this study. Mandibular first molars were ligated with 3–0 silk suture. The rats received daily doses of 0.09% NaCl (control group) or 10 mg/kg body weight of CsA (test group) by intraperitoneal injections. Five rats from the control group and 10 rats from the test group were sacrificed at each experimental period (2, 4, 6, and 8 weeks after the beginning of CsA treatment). The specimens were examined immunohistochemically. Results: CD4+, CD8+, and CD45RO+ T cells, and VEGF expression were more prevalent in the CsA‐treated group than in the control group (P <0.05). VEGF was significantly correlated with CD4+ T cells, CD4+/CD8+ ratio, and CD45RO+ cells (P <0.05). Conclusion: Based on our findings, we conclude that VEGF, a major regulator of angiogenesis, and CD4+, CD8+, and CD45RO+ memory T cells play a key role in CsA‐induced gingival overgrowth. 相似文献
53.
Rehab A. Karam Noha A. Rezk Hadeel M. Abdelrahman Tamer H. Hassan Doaa Mohammad Haitham M. Hashim Nelly R.A. Abdel Fattah 《Research in developmental disabilities》2013,34(7):2092-2097
Catechol-O-methyltransferase (COMT) plays an important role in the catabolism of brain dopamine and norepinephrine, which have been implicated in the pathogenesis of Autism spectrum disorder (ASD) as well as in other neuropsychatric disorders. We aimed to investigate the association of COMT Val158Met gene polymorphism with ASD and to examine the influence of such genotypes on hyperactivity symptoms in ASD patients. Eighty ASD patients (mean age 9 ± 1.9 years) and 100 control children (mean age 8.9 ± 1.9 years) were examined. COMT Val58Met polymorphism was genotyped using Tetra-primer ARMS-PCR method. The clinical diagnosis of ASD and ADHD were confirmed according to the DSM-IV criteria for research. We found no significant difference in genotypes or alleles’ frequencies of COMT Val158Met polymorphism between ASD patients and control group. There was a significant association between COMT (Val/Val) genotype and both increasing CARS (p = 0.001) and hyperactivity scores (p = 0.006). Regarding Conner's Score, the DSM-IV hyperactive impulsive were significantly higher in Val/Val genotype than both Met/Val and Met/Met genotypes (p = 0.03). Our data suggested an association between COMT Val58Met polymorphism and hyperactivity symptoms in Egyptian children with ASD. 相似文献
54.
55.
Alloush Taha K. Mansour Osama Alloush Adel T. Roushdy Tamer Hamid Eman El-Shamy Mahmoud Shokri Hossam M. 《Neurological sciences》2022,43(2):799-809
Neurological Sciences - COVID-19 is a pandemic disease which predominantly affects the respiratory system with high critical care mortality and morbidity; however, it also causes multi-organ... 相似文献
56.
Chan Yong Schüle Bente Thamsen Bastian Blümel Michael Lommel Tamer Karakaya Christian Oliver Paschereit Klaus Affeld Ulrich Kertzscher 《Artificial organs》2016,40(11):E192-E202
Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near‐wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds‐averaged Navier–Stokes simulations‐computational fluid dynamics (URANS‐CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall‐particle image velocimetry technique, and the visualization of near‐wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS‐CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal. 相似文献
57.
Baculovirus-insect cell system (BICS) is considered one of the most efficient eukaryotic gene expression systems. This system has also been used for producing different recombinant baculoviruses with increased insect toxicity as potential biopesticides. Establishing a universal gene silencing (UGS) system is very important due to the increasing number of studies using RNA interference (RNAi) with BICS. In this work, the enhanced green fluorescent protein (EGFP) was used as the RNAi consistent target sequence located downstream of a depressant insect-neurotoxin gene, LqqIT2 used as a model of the gene of interest. Small interfering RNA (siRNA) and inverted repeats of EGFP gene (IR-EG) were examined in targeting the EGFP-LqqIT2 (EL)-fusion mRNA or LqqIT2-EGFP (LE)-bicistronic mRNA for degradation. Suppression efficiencies using these inducers were examined transiently and stably in uninfected and infected insect Sf9 cells. Moreover, RNAi showed persistence for 4 and 8 days in baculovirus-infected as well as uninfected Sf9 cells, respectively. Bicistronic RNA seems an efficient way to lower cost and effort of the gene silencing approach while maintaining the biological activity of the protein of interest when the RNAi is not in use. 相似文献
58.
59.
60.
Assessment of left ventricular diastolic function with Doppler tissue imaging: effects of preload and place of measurements 总被引:6,自引:2,他引:6
Dincer I Kumbasar D Nergisoglu G Atmaca Y Kutlay S Akyurek O Sayin T Erol C Oral D 《The international journal of cardiovascular imaging》2002,18(3):155-160
Mitral inflow velocities are widely used for the evaluation of left ventricular (LV) diastolic function. However, they are closely affected by other factors such as preload. The purpose of this study was to evaluate the usefulness of tissue Doppler velocities obtained from the mitral annulus for the evaluation of ventricular relaxation in patients under different loading conditions. We also evaluated the effect of preload at different sides on the mitral annulus. The study population consisted of 62 consecutive patients (38 male, 24 female with a mean age of 42 ± 13 years) who have undergone hemodialysis. Both mitral inflow velocities (E wave, A wave, E wave deceleration time and isovolumetric relaxation time) and mitral annulus tissue Doppler velocities (E, A) from the septal, lateral, anterior, posterolateral and inferior sides of the mitral annulus were measured immediately before and after hemodialysis. Mitral inflow E and A wave velocities and E/A ratio decreased significantly (p < 0.001, p = 0.007, p < 0.001, respectively) after hemodialysis. Mitral annulus E wave velocities and E/A ratios obtained from five different sides of the annulus also changed significantly (p < 0.001 for all); however, there was no change in the A wave velocity (p > 0.05 for all) after hemodialysis. The decrease in E wave and E/A ratio in mitral inflow measurements and E velocities and E/A ratios in tissue Doppler measurements were correlated with the amount of fluid extracted (for mitral inflow E wave, r = 0.392, p = 0.002 and E/A ratio, r = 0.280 and p = 0.027; for lateral side E, r = 0.329, p = 0.009 and E/A ratio, r = 0.286, p = 0.04; for septal side E, r = 0.376, p = 0.003 and E/A ratio, r = 0.297, p = 0.019; for anterior side E, r = 0.342, p = 0.007 and E/A ratio, r = 0.268, p = 0.035; for posterolateral side E, r = 0.423, p = 0.001 and E/A ratio, r = 0.343, p = 0.007; and for inferior side E, r = 0.326, p = 0.01 and E/A ratio, r = 0.278, p = 0.029). We conclude that mitral annular velocities obtained by tissue Doppler are preload dependent parameters for the evaluation of LV diastolic function. 相似文献