全文获取类型
收费全文 | 446篇 |
免费 | 29篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 23篇 |
妇产科学 | 7篇 |
基础医学 | 66篇 |
口腔科学 | 12篇 |
临床医学 | 50篇 |
内科学 | 91篇 |
皮肤病学 | 19篇 |
神经病学 | 22篇 |
特种医学 | 49篇 |
外科学 | 42篇 |
综合类 | 17篇 |
预防医学 | 28篇 |
眼科学 | 21篇 |
药学 | 23篇 |
肿瘤学 | 9篇 |
出版年
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 21篇 |
2010年 | 24篇 |
2009年 | 28篇 |
2008年 | 26篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 23篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 19篇 |
1997年 | 22篇 |
1996年 | 22篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 10篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1948年 | 1篇 |
1947年 | 1篇 |
1940年 | 1篇 |
1928年 | 2篇 |
排序方式: 共有488条查询结果,搜索用时 0 毫秒
41.
Anderson JG Fordahl SC Cooney PT Weaver TL Colyer CL Erikson KM 《Neurotoxicology》2008,29(6):1044-1053
Unlike other essential trace elements (e.g., zinc and iron) it is the toxicity of manganese (Mn) that is more common in human populations than its deficiency. Data suggest alterations in dopamine biology may drive the effects associated with Mn neurotoxicity, though recently γ-aminobutyric acid (GABA) has been implicated. In addition, iron deficiency (ID), a common nutritional problem, may cause disturbances in neurochemistry by facilitating accumulation of Mn in the brain. Previous data from our lab have shown decreased brain tissue levels of GABA as well as decreased 3H-GABA uptake in synaptosomes as a result of Mn exposure and ID. These results indicate a possible increase in the concentration of extracellular GABA due to alterations in expression of GABA transport and receptor proteins. In this study weanling-male Sprague–Dawley rats were randomly placed into one of four dietary treatment groups: control (CN; 35 mg Fe/kg diet), iron-deficient (ID; 6 mg Fe/kg diet), CN with Mn supplementation (via the drinking water; 1 g Mn/l) (CNMn), and ID with Mn supplementation (IDMn). Using in vivo microdialysis, an increase in extracellular GABA concentrations in the striatum was observed in response to Mn exposure and ID although correlational analysis reveals that extracellular GABA is related more to extracellular iron levels and not Mn. A diverse effect of Mn exposure and ID was observed in the regions examined via Western blot and RT-PCR analysis, with effects on mRNA and protein expression of GAT-1, GABAA, and GABAB differing between and within the regions examined. For example, Mn exposure reduced GAT-1 protein expression by approximately 50% in the substantia nigra, while increasing mRNA expression approximately four-fold, while in the caudate putamen mRNA expression was decreased with no effect on protein expression. These data suggest that Mn exposure results in an increase in extracellular GABA concentrations via altered expression of transport and receptor proteins, which may be the basis of the neurological characteristics of manganism. 相似文献
42.
The serotonin2A receptor (5-HT2AR) is implicated in many neurological disorders and has a role in cognitive processes, reliant upon hippocampal glutamate receptors. Recent studies show that 5-HT2AR agonists and/or antagonists can influence cognitive function, suggesting a critical hippocampal role for these receptors, yet their cellular and subcellular distribution within this region has not been comprehensively analysed. Here, we have conducted an electron microscopic examination of 5-HT2AR distribution with the glutamate N-methyl-d-aspartate (NMDA) and amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptor subunits NR1 and GluR2 in the hippocampal dentate gyrus (DG) in order to investigate whether 5-HT2AR location is compatible with a modulatory role over NMDA and/or AMPA receptor mediated neurotransmission. Of 5-HT2AR positive profiles, 56% were dendrites and 16% were dendritic spines. Labelling was both cytoplasmic and membranous. Spinous labelling was more frequently membranous at peri- and extra-synaptic sites, though was also associated with synaptic specialisations. Profiles displaying colocalisation of immunoreactivity for 5-HT2ARs with NR1 or GluR2 were predominantly dendrites, representing 11% and 8% of 5-HT2AR positive profiles, respectively. Additionally, 12% of 5-HT2AR labelled profiles also displayed immunoreactivity for γ-aminobutyric acid (GABA). These data indicate most 5-HT2ARs are expressed on granule cell projections, with a smaller subpopulation expressed on GABAergic interneurons. 相似文献
43.
Background
The Abductor hallucis muscle (AbdH) plays an integral role during gait and is often affected in pathological foot conditions. The aim of this study was to evaluate the within and between-session intra-tester reliability using diagnostic ultrasound of the dorso-plantar thickness, medio-lateral width and cross-sectional area, of the AbdH in asymptomatic adults.Methods
The AbdH muscles of thirty asymptomatic subjects were imaged and then measured using a Philips HD11 Ultrasound machine. Interclass correlation coefficients (ICC) with 95% confidence intervals (CI) were used to calculate both within and between session intra-tester reliability.Results
The within-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.99–0.99); medio-lateral width an ICC: of 0.97 (95% CI: 0.92–0.97) and cross-sectional area an ICC of 0.98 (95% CI: 0.98–0.99). Between-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.95 to 0.98); medio-lateral width an ICC of 0.94 (95% CI 0.90 to 0.96) and for cross-sectional area an ICC of 0.79 (95% CI 0.65 to 0.88).Conclusion
Diagnostic ultrasound has the potential to be a reliable tool for evaluating the AbdH muscle in asymptomatic subjects. Subsequent studies may be conducted to provide a better understanding of the AbdH function in foot and ankle pathologies. 相似文献44.
Grace Gard Joanna Oakley Michael Harold Duncan Colyer Wendy Benson Katya Gray Nik Zeps Peter Gibbs 《Internal medicine journal》2023,53(11):2111-2114
Clinical trials offer access to novel therapies and potential major benefits for patients, but identifying and accessing suitable trials remains a significant challenge for consumers. A burgeoning range of online services aims to meet this need; however, there is a paucity of data on whether these services are addressing the requirements and concerns of consumers. Here, we report our findings from a survey of cancer consumers, with results we believe are relevant to the broader research community. 相似文献
45.
46.
47.
48.
49.
Adherence of L1210 murine leukemia cells to sephacryl- aminopropylcobalamin beads treated with transcobalamin-II 总被引:1,自引:0,他引:1
Sephacryl beads containing an immobilized aminopropylcobalamin- transcobalamin-II complex serve as foci for the adherence of L1210 murine leukemia cells. Bead-cell interaction does not occur when (A) nonderivatized beads are used; (B) transcobalamin-II is omitted or presaturated with cyanocobalamin in the preparation of the bead complex; (C) intrinsic factor replaces transcobalamin-II; and (D) the complex is removed from beads by photolysis. These observations suggest that adherence results from the ability of transcobalamin-II to form a bridge between immobilized cobalamin on the bead and receptors in the plasma membrane of the cell. 相似文献
50.
Hematopoietic progenitors and interleukin-3-dependent cell lines synthesize histamine in response to calcium ionophore 总被引:1,自引:1,他引:1
The calcium ionophore A23187 promotes histamine synthesis in murine bone marrow cells by increasing the expression of mRNA encoding histidine decarboxylase (HDC), the histamine-forming enzyme. The cells responsible for this biological activity copurify with hematopoietic progenitors in terms of density, light scatter characteristics, and rhodamine retention, similar to interleukin (IL) 3-induced histamine- producing cells. Yet, the effect of calcium ionophore is not mediated by IL-3. The most purified rhodamine-bright bone marrow subset contains 80% cells that respond to calcium ionophore by increased HDC mRNA expression. This high frequency makes the involvement of one particular progenitor subset in histamine synthesis unlikely. The finding that all IL-3-dependent cell lines tested so far exhibit increased histamine production and HDC mRNA expression in response to calcium influx lends further support to this notion. Cell lines requiring other growth factors or proliferating spontaneously lack this ability. Finally, it should be noted that IL-3-dependent cell lines do not produce histamine in response to their growth factor. It might, therefore, be suggested that the pathway transducing the signal for increased histamine synthesis after IL-3 receptor binding in normal hematopoietic progenitors is modified in these cell lines. 相似文献