全文获取类型
收费全文 | 3715篇 |
免费 | 164篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 122篇 |
儿科学 | 219篇 |
妇产科学 | 218篇 |
基础医学 | 254篇 |
口腔科学 | 188篇 |
临床医学 | 253篇 |
内科学 | 717篇 |
皮肤病学 | 75篇 |
神经病学 | 308篇 |
特种医学 | 150篇 |
外科学 | 986篇 |
综合类 | 33篇 |
一般理论 | 1篇 |
预防医学 | 69篇 |
眼科学 | 73篇 |
药学 | 101篇 |
中国医学 | 1篇 |
肿瘤学 | 138篇 |
出版年
2024年 | 4篇 |
2023年 | 38篇 |
2022年 | 70篇 |
2021年 | 125篇 |
2020年 | 94篇 |
2019年 | 103篇 |
2018年 | 123篇 |
2017年 | 107篇 |
2016年 | 156篇 |
2015年 | 180篇 |
2014年 | 198篇 |
2013年 | 230篇 |
2012年 | 328篇 |
2011年 | 293篇 |
2010年 | 160篇 |
2009年 | 148篇 |
2008年 | 267篇 |
2007年 | 278篇 |
2006年 | 229篇 |
2005年 | 213篇 |
2004年 | 148篇 |
2003年 | 108篇 |
2002年 | 116篇 |
2001年 | 35篇 |
2000年 | 34篇 |
1999年 | 28篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 18篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有3906条查询结果,搜索用时 15 毫秒
121.
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
122.
Bulent Erdogan Ozgur Yaycioglu Iffet Feride Sahin Fazilet Kayaselcuk Berker Cemil Emre Cemal Gokce Murad Bavbek 《Neurologia i neurochirurgia polska》2013,47(2):138-144
Background and purposeIn continuation of our previous experimental study on spinal cord injury (SCI) using fetal stem cells, we investigated here the effects of fetal allogeneic umbilical cord tissue transplant on the urinary bladder morphology in a rat SCI model.Material and methodsFive pregnant albino Wistar rats at 12 days of gestation were used to obtain the umbilical cord cell graft. In Group 1 (n = 5), Th8-Th9 laminectomy was performed. Group 2 (n = 5) received spinal cord injury. In Group 3 (n = 5), the cultured fetal umbilical cord cells coated with alginate gel were placed into the lesion cavity. In Group 4 (n = 5), only alginate sponges without umbilical cord cells were placed into the injury cavity. The bladders of animals were analyzed pathologically at 21 days after surgery.ResultsThe thickness of the epithelium and the lamina propria did not differ among studied groups (p > 0.05). The lamina muscularis thickness was significantly higher in Group 2 and Group 4 than the others (p < 0.05). The bladder weight was similar among Groups 1, 2, and 3 (p > 0.05). Fibrosis was significantly increased in Group 2 (p < 0.05); it was greater in Group 2 than in Group 3 (p < 0.05) but did not differ between Groups 1 and 3 (p > 0.05).ConclusionsThis study suggests that allogeneic umbilical cord tissue transplantation after SCI may prevent bladder wall hypertrophy and fibrosis in the rat SCI model. 相似文献
123.
We tested human participants on a modified peak procedure in order to investigate the relation between interval timing and reward processing, and examine the interaction of this relation with three different dopamine-related gene polymorphisms. These gene polymorphisms affected the expression of catechol-o-methyltransferase, which catabolizes synaptic dopamine primarily in the prefrontal cortex (COMT Val158Met polymorphism), D2 dopamine receptors primarily in the striatum (DRD2/ANKK1-Taq1a polymorphism), and dopamine transporters, which clear synaptic dopamine in the striatum (DAT 3′ VNTR variant). The inclusion of these polymorphisms allowed us to investigate dissociable aspects of the dopamine system and their interaction with reward magnitude manipulations in shaping timed behavior. These genes were chosen for their roles in reward processing and cortico-striatal information processing that have been implicated for interval timing. Consistent with recent animal studies, human participants initiated their timed anticipatory responding earlier when expecting a larger reward in the absence of any changes in the timing of response termination or perceived time. This effect however was specific to two out of four evaluated COMT and DRD2 polymorphism combinations that lead to high prefrontal dopamine coupled with high D2 density and low prefrontal dopamine coupled with low D2 density. Larger rewards also decreased timing precision indices, some of which interacted with the COMT polymorphism. Furthermore, the COMT polymorphism that leads to higher prefrontal dopamine resulted in weaker manifestation of memory variability (relative to threshold variability) in timed behavior. There was no effect of DAT polymorphisms on any of the core behavioral measures. These results suggest that the reward modulates decision thresholds rather than clock speed, and that these effects are specific to COMT and DRD2 epistasis effects that presumably constitute a balanced prefrontal and striatal dopamine transmission. 相似文献
124.
Murtaza Emre Durakoğlugil MD Yüksel Çiçek MD Sinan Altan Kocaman MD Mehmet Sabri Balik MD Serkan Kirbaş MD Mustafa Çetin MD Turan Erdoğan MD Aytun Çanga MD 《Muscle & nerve》2013,47(6):872-877
Introduction: Carpal tunnel syndrome (CTS) is associated with cardiovascular risk factors. The aim of our study was to determine whether carotid intima–media thickness (CIMT) and carotid–femoral pulse wave velocity (cf-PWV), as surrogates of cardiovascular disease and arterial stiffness, are increased in patients with carpal tunnel syndrome. Methods: Forty patients with CTS and 40 gender- and age-matched controls underwent cf-PWV assessment, CIMT measurement, and nerve conduction study. Results: CIMT and cf-PWV were increased significantly in patients with CTS. They correlated positively with median sensory and motor nerve distal latency. Whereas both CIMT and PWV related to CTS, only CIMT independently predicted CTS. Conclusions: There is both increased pulse wave velocity and CIMT and a positive correlation between these parameters and median nerve sensory distal latency in patients with CTS. CTS appears to be associated with arterial stiffness and atherosclerotic burden, but the underlying mechanisms require further study. Muscle Nerve 47: 872–877, 2013 相似文献
125.
126.
Oguz Gozen Burcu Balkan Emre Yildirim Ersin O. Koylu Sakire Pogun 《Synapse (New York, N.Y.)》2013,67(9):545-552
Nicotine is a highly addictive drug and exerts its effect partially through causing dopamine release, thereby increasing intrasynaptic dopamine levels in the brain reward systems. Dopaine D1 receptor (DRD1) mRNAs and receptors are localized in reward‐related brain regions, which receive cholinergic input. The aim of this study is to evaluate whether nicotine administration affects the expression of DRD1s, and if so, whether epigenetic mechanisms, such as histone acetylation, are involved. Twenty Male Sprague Dawley rats received nicotine (0.4 mg/kg/day, s.c.) or saline injections for 15 days. After nicotine/saline treatment, rats were perfused with saline; prefrontal cortex (PFC), corpus striatum (STR), and ventral tegmental area (VTA) were dissected. Homogenates were divided into two parts for total RNA isolation and histone H4 acetylation studies. DRD1 mRNA expression was significantly higher in the PFC of the nicotine‐treated group compared with controls; similar trends were observed in the VTA and STR. To study epigenetic regulation, the 2kb upstream region of the DRD1 gene promoter was investigated for histone H4 acetylation in PFC samples. After chromatin immunoprecipitation with anti‐acetyl histone H4 antibody, we found an increase in histone acetylation by two different primer pairs which amplified the ?1365 to ?1202 (P < 0.005) and ?170 to +12 (P < 0.05) upstream regions of the DRD1 promoter. Our results suggest that intermittent subcutaneous nicotine administration increases the expression of DRD1 mRNA in the PFC of rats, and this increase may be due to changes in histone H4 acetylation of the 2kb promoter of the DRD1 gene. Synapse 67:545–552, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
127.
Sezer Eda Can Demirden Birsen Demirkaya eref Bulut Giray Akkulak Merve Evin Emre Adal Orhan 《Neurological sciences》2022,43(4):2611-2620
Neurological Sciences - Patients with multiple sclerosis (MS) have significantly lower vitamin D levels. Cholesterol is known to be the precursor for vitamin D synthesis, and cholesterol removal is... 相似文献
128.
129.
130.