全文获取类型
收费全文 | 1671篇 |
免费 | 76篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 31篇 |
妇产科学 | 35篇 |
基础医学 | 259篇 |
口腔科学 | 33篇 |
临床医学 | 148篇 |
内科学 | 315篇 |
皮肤病学 | 35篇 |
神经病学 | 177篇 |
特种医学 | 130篇 |
外科学 | 299篇 |
综合类 | 13篇 |
预防医学 | 55篇 |
眼科学 | 20篇 |
药学 | 76篇 |
中国医学 | 2篇 |
肿瘤学 | 93篇 |
出版年
2023年 | 20篇 |
2022年 | 30篇 |
2021年 | 48篇 |
2020年 | 29篇 |
2019年 | 31篇 |
2018年 | 52篇 |
2017年 | 31篇 |
2016年 | 44篇 |
2015年 | 39篇 |
2014年 | 60篇 |
2013年 | 94篇 |
2012年 | 109篇 |
2011年 | 117篇 |
2010年 | 60篇 |
2009年 | 54篇 |
2008年 | 103篇 |
2007年 | 108篇 |
2006年 | 79篇 |
2005年 | 97篇 |
2004年 | 82篇 |
2003年 | 80篇 |
2002年 | 75篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1956年 | 4篇 |
1943年 | 4篇 |
1935年 | 4篇 |
1933年 | 19篇 |
1932年 | 4篇 |
1931年 | 5篇 |
1930年 | 7篇 |
1929年 | 4篇 |
1925年 | 5篇 |
1922年 | 4篇 |
1914年 | 3篇 |
1913年 | 5篇 |
1912年 | 5篇 |
排序方式: 共有1751条查询结果,搜索用时 562 毫秒
41.
Erwin?Stolz Franziska?Gro?sch?dl Hannes?Mayerl éva?Rásky Wolfgang?FreidlEmail author 《BMC medical ethics》2015,16(1):81
Background
End-of-life decisions remain a hotly debated issue in many European countries and the acceptance in the general population can act as an important anchor point in these discussions. Previous studies on determinants of the acceptance of end-of-life interventions in the general population have not systematically assessed whether determinants differ between withdrawal of life-prolonging treatment (WLPT) and euthanasia (EUT).Methods
A large, representative survey of the Austrian adult population conducted in 2014 (n?=?1,971) included items on WLPT and EUT. We constructed the following categorical outcome: (1) rejection of both WLPT and EUT, (2) approval of WLPT but rejection of EUT, and (3) approval of both WLPT and EUT. The influence of socio-demographics, personal experiences, and religious and socio-cultural orientations on the three levels of approval were assessed via multinomial logistic regression analysis.Results
Higher education and stronger socio-cultural liberal orientations increased the likelihood of approving both WLPT and EUT; personal experience with end-of-life care increased only the likelihood of approval of WLPT; and religiosity decreased approval of EUT only.Conclusion
This study found evidence for both shared (education, liberalism) and different (religiosity, care experiences) determinants for the acceptance of WLPT and EUT.42.
Michaela Lackner Ulrike Binder Martin Reindl Beyhan G?nül Hannes Fankhauser Christian Mair Markus Nagl 《Antimicrobial agents and chemotherapy》2015,59(10):6454-6462
N-Chlorotaurine (NCT), a well-tolerated endogenous long-lived oxidant that can be applied topically as an antiseptic, was tested on its fungicidal activity against Scedosporium and Lomentospora, opportunistic fungi that cause severe infections with limited treatment options, mainly in immunocompromised patients. In quantitative killing assays, both hyphae and conidia of Scedosporium apiospermum, Scedosporium boydii, and Lomentospora prolificans (formerly Scedosporium prolificans) were killed by 55 mM (1.0%) NCT at pH 7.1 and 37°C, with a 1- to 4-log10 reduction in CFU after 4 h and a 4- to >6-log10 reduction after 24 h. The addition of ammonium chloride to NCT markedly increased this activity. LIVE/DEAD staining of conidia treated with 1.0% NCT for 0.5 to 3 h increased the permeability of the cell wall and membrane. Preincubation of the test fungi in 1.0% NCT for 10 to 60 min delayed the time to germination of conidia by 2 h to >12 h and reduced their germination rate by 10.0 to 100.0%. Larvae of Galleria mellonella infected with 1.0 × 107 conidia of S. apiospermum and S. boydii died at a rate of 90.0 to 100% after 8 to 12 days. The mortality rate was reduced to 20 to 50.0% if conidia were preincubated in 1.0% NCT for 0.5 h or if heat-inactivated conidia were used. Our study demonstrates the fungicidal activity of NCT against different Scedosporium and Lomentospora species. A postantifungal effect connected with a loss of virulence occurs after sublethal incubation times. The augmenting effect of ammonium chloride can be explained by the formation of monochloramine. 相似文献
43.
Ahmet Arac Michele A. Grimbaldeston Andrew R.B. Nepomuceno Oluwatobi Olayiwola Marta P. Pereira Yasuhiro Nishiyama Anna Tsykin Gregory J. Goodall Ulrich Schlecht Hannes Vogel Mindy Tsai Stephen J. Galli Tonya M. Bliss Gary K. Steinberg 《The American journal of pathology》2014,184(9):2493-2504
Stroke is the leading cause of adult disability and the fourth most common cause of death in the United States. Inflammation is thought to play an important role in stroke pathology, but the factors that promote inflammation in this setting remain to be fully defined. An understudied but important factor is the role of meningeal-located immune cells in modulating brain pathology. Although different immune cells traffic through meningeal vessels en route to the brain, mature mast cells do not circulate but are resident in the meninges. With the use of genetic and cell transfer approaches in mice, we identified evidence that meningeal mast cells can importantly contribute to the key features of stroke pathology, including infiltration of granulocytes and activated macrophages, brain swelling, and infarct size. We also obtained evidence that two mast cell-derived products, interleukin-6 and, to a lesser extent, chemokine (C-C motif) ligand 7, can contribute to stroke pathology. These findings indicate a novel role for mast cells in the meninges, the membranes that envelop the brain, as potential gatekeepers for modulating brain inflammation and pathology after stroke.Stroke, the leading cause of adult disability and the fourth most common cause of death in the Unites States,1,2 occurs when there is insufficient blood flow to the brain, and the resultant injury initiates a cascade of inflammatory events, including immune cell infiltration into the brain.3–5 This post-stroke inflammation is a critical determinant of damage and recovery after stroke; understanding the interplay between the immune system and the brain after stroke holds much promise for therapeutic intervention.4–7 However, successfully exploiting this therapeutic potential requires a detailed understanding of the interplay between the immune system and the brain after stroke.4An understudied but important aspect of this interplay is the role of meningeal-located immune cells in modulating brain pathology. The meninges have long been recognized as an anatomical barrier that protects the central nervous system (CNS). However, accumulating evidence suggests that the meninges are important for communication between the CNS and immune system during health and disease.8–10 All blood vessels pass through the meningeal subarachnoid space before entering the brain, and this vascular connection and the close proximity of the meninges to the underlying parenchymal nervous tissue make them ideally located to act as a gatekeeper to modulate immune cell trafficking to the CNS. To support this gatekeeper function is evidence that the meninges modulate brain infiltration of T cells, neutrophils, and monocytes during meningitis and autoimmune conditions,11–14 with immune cells observed in some instances accumulating in the meninges before they infiltrate into the parenchyma.11,13Emerging evidence suggests that the actions of immune cells resident in the meninges are important for this gatekeeper function.11,12,15 Mast cells (MCs), best known as proinflammatory effector cells, can play critical roles in the development of inflammation in many disease settings.16–18 MCs reside in high numbers within the meninges, but their function in this site has not been fully investigated in stroke pathology. Unlike most immune cells, mature MCs do not circulate in the blood but are long-term residents of tissues, often in perivascular locations, and can rapidly perform their functions in situ. CNS MCs are found in the brain parenchyma and the meninges of rodents and humans.18 It has been proposed that brain parenchymal MCs can enhance brain neutrophil numbers after stroke and can exacerbate stroke pathology.19–24 However, much of the evidence to support such conclusions is indirect. For example, some of the studies that implicate MCs in stroke pathology used pharmacologic approaches to interfere with MC activation,19,20,22 but such drugs can have effects on other cell types.25 Moreover, the role of the meningeal MCs in modulating post-stroke inflammation and pathology is unknown. Finally, little is understood about which among the many MC-derived mediators may be important in stroke pathology.17,26To address these questions, we used genetic and cell transfer approaches to study the role of MCs in the pathology of ischemic stroke in mice. Specifically, we tested a c-kit–mutant mouse model (ie, WBB6F1-KitW/W-v mice) which is profoundly MC deficient and can be repaired of this deficiency by engraftment of in vitro-derived MCs from wild-type (WT) mice. This MC knock-in approach enables the MC-dependent effects in the mutant mice to be separated from effects due to other abnormalities associated with their mutation,11,17,26,27 because only the MC deficiency is repaired by MC engraftment. Furthermore, one can investigate the mechanisms by which MCs influence stroke pathology by engrafting MCs from transgenic mice that lack specific MC-associated products. We also tested our newly described Cpa3-Cre; Mcl-1fl/fl mice, in which MC (and basophil) numbers are reduced constitutively via Cre-mediated depletion of the anti-apoptotic factor, myeloid cell leukemia sequence 1 (Mcl-1), in the affected lineages.28
Cpa3-Cre; Mcl-1fl/fl mice lack the other abnormalities associated with the c-kit mutations in WBB6F1-KitW/W-v mice.28With the use of these in vivo models, we identified meningeal MCs as important contributors to key features of stroke pathology, including increased numbers of brain granulocytes and activated macrophages, brain swelling, and infarct size. We also obtained evidence that two potentially proinflammatory MC-derived products, IL-6 and, to a lesser extent, chemokine (C-C motif) ligand 7 (CCL7), can contribute to pathology in this setting. 相似文献
44.
Colin K. Khoury Anne D. Bjorkman Hannes Dempewolf Julian Ramirez-Villegas Luigi Guarino Andy Jarvis Loren H. Rieseberg Paul C. Struik 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(11):4001-4006
The narrowing of diversity in crop species contributing to the world’s food supplies has been considered a potential threat to food security. However, changes in this diversity have not been quantified globally. We assess trends over the past 50 y in the richness, abundance, and composition of crop species in national food supplies worldwide. Over this period, national per capita food supplies expanded in total quantities of food calories, protein, fat, and weight, with increased proportions of those quantities sourcing from energy-dense foods. At the same time the number of measured crop commodities contributing to national food supplies increased, the relative contribution of these commodities within these supplies became more even, and the dominance of the most significant commodities decreased. As a consequence, national food supplies worldwide became more similar in composition, correlated particularly with an increased supply of a number of globally important cereal and oil crops, and a decline of other cereal, oil, and starchy root species. The increase in homogeneity worldwide portends the establishment of a global standard food supply, which is relatively species-rich in regard to measured crops at the national level, but species-poor globally. These changes in food supplies heighten interdependence among countries in regard to availability and access to these food sources and the genetic resources supporting their production, and give further urgency to nutrition development priorities aimed at bolstering food security.A shared axiom of ecology and nutrition is that, within certain ranges, diversity enhances the health and function of complex biological systems. Species diversity has been shown to stimulate productivity, stability, ecosystem services, and resilience in natural (1–5) and in agricultural ecosystems (6–13). Likewise, variation in food species contributing to diet has been associated with nutritional adequacy (14–17) and food security (18).The development of sedentary agricultural societies and further rise of modern agriculture is generally considered to have led to a decline in the total number of plant species upon which humans depend for food (19, 20), particularly the wild, semidomesticated, and cultivated vegetables and fruits, spices, and other food plants that supplemented staple crops with the provision of micronutrients and that bolstered food security historically during crop failures (21). Harlan (20) warned that
most of the food for mankind comes from a small number of crops and the total number is decreasing steadily. In the United States in the past 40 years, many vegetables and fruits have disappeared from the diet, and the trend is going on all over the world. More and more people will be fed by fewer and fewer crops.More recent analyses of dietary transition in developing countries in association with globalization have noted increases in the diversity of plants contributing to diets locally, along with a Westernization transition in preference of energy-dense foods (i.e., animal products, plant oils, and sugars) over cereals, pulses, and vegetables, and of particular major crop plants within these food categories over traditional crops (22, 23). The impact of such changes on overall crop diversity worldwide has not been comprehensively documented, although recent changes in varietal and allelic level diversity of some crops have been investigated (24–26). Given the potential food security implications of narrowing of the diversity of crop species both in production systems and in food supplies, an assessment of the global state of crop plant species diversity is warranted.Here we examine changes in the diversity of the portfolio of crop species upon which humans primarily depend for food security in regard to calories, protein, fat, and food weight. Using national per capita food supply data published by the Food and Agriculture Organization (FAO) of the United Nations, we analyzed trends in the richness, abundance, and composition of measured crop commodities in the food supplies of 152 countries comprising 98% of the world’s population from 1961 to 2009. 相似文献
45.
Hendrik Ruge Magdalena Erlebach Eveline Lieberknecht Rüdiger Lange 《Catheterization and cardiovascular interventions》2020,95(4):859-862
Transcatheter heart valve implantation into degenerated bioprosthetic valves (ViV‐THV implantation) has become an established procedure for high risk patients. In general, paravalvular leak (PVL) is a contraindication for valve‐in‐valve‐TAVR (ViV‐TAVR). Herein, we report on a 81‐year‐old patient presenting with acute heart failure for a failing aortic bioprosthesis (Medtronic Mosaic 27 mm). Intraoperative transesophageal echocardiography during urgent ViV‐TAVR revealed a PVL previously not detected. After transfemoral implantation of a 26 mm‐Evolut‐R, balloon‐fracturing of the bioprosthetic ring was performed using a 24 mm True Dilatation balloon for treatment of the PVL. Afterward, left ventricular to aortic peak‐to‐peak pressure gradient measured 2–4mmHg. Transesophageal echocardiography merely revealed trace PVL. Aortic root angiography showed no PVL. At discharge, echocardiography measured a transprosthetic mean gradient of 5mmHg detecting no PVL. Intentional ring‐fracturing of an aortic valve prostheses may prove not only to be effective in lowering transvalvular gradients after valve‐in‐valve‐TAVR, but may also be a tool to treat PVL alongside degenerated surgical aortic bioprostheses in certain patients. 相似文献
46.
Halbach M Krausgrill B Hannes T Wiedey M Peinkofer G Baumgartner S Sahito RG Pfannkuche K Pillekamp F Reppel M Müller-Ehmsen J Hescheler J 《Journal of molecular and cellular cardiology》2012,53(3):401-408
Electrophysiological maturation and integration of transplanted cardiomyocytes are essential to enhance safety and efficiency of cell replacement therapy. Yet, little is known about these important processes. The aim of our study was to perform a detailed analysis of electrophysiological maturation and integration of transplanted cardiomyocytes. Fetal cardiomyocytes expressing enhanced green fluorescent protein were transplanted into cryoinjured mouse hearts. At 6, 9 and 12days after transplantation, viable slices of recipient hearts were prepared and action potentials of transplanted and host cardiomyocytes within the slices were recorded by microelectrodes. In transplanted cells embedded in healthy host myocardium, action potential duration at 50% repolarization (APD50) decreased from 32.2±3.3ms at day 6 to 27.9±2.6ms at day 9 and 19.6±1.6ms at day 12. The latter value matched the APD50 of host cells (20.5±3.2ms, P=0.78). Integration improved in the course of time: 26% of cells at day 6 and 53% at day 12 revealed no conduction blocks up to a stimulation frequency of 10Hz. APD50 was inversely correlated to the quality of electrical integration. In transplanted cells embedded into the cryoinjury, which showed no electrical integration, APD50 was 49.2±4.3ms at day 12. Fetal cardiomyocytes transplanted into healthy myocardium integrate electrically and mature after transplantation, their action potential properties after 12days are comparable to those of host cardiomyocytes. Quality of electrical integration improves over time, but conduction blocks still occur at day 12 after transplantation. The pace of maturation correlates with the quality of electrical integration. Transplanted cells embedded in cryoinjured tissue still possess immature electrophysiological properties after 12days. 相似文献
47.
Ruge T Sukonina V Kroupa O Makoveichuk E Lundgren M Svensson MK Olivecrona G Eriksson JW 《Metabolism: clinical and experimental》2012,61(5):652-660
Our aims were to compare the systemic effects of insulin on lipoprotein lipase (LPL) in tissues from subjects with different degrees of insulin sensitivity. The effects of insulin on LPL during a 4-hour hyperinsulinemic, euglycemic clamp were studied in skeletal muscle, adipose tissue, and postheparin plasma from young healthy subjects (YS), older subjects with type 2 diabetes mellitus (DS), and older control subjects (CS). In addition, we studied the effects of insulin on the expression of 2 recently recognized candidate genes for control of LPL activity: angiopoietin-like protein 4 (ANGPTL4) and glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1. As an effect of insulin, LPL activity decreased by 20% to 25% in postheparin plasma and increased by 20% to 30% in adipose tissue in all groups. In YS, the levels of ANGPTL4 messenger RNA in adipose tissue decreased 3-fold during the clamp. In contrast, there was no significant change in DS or CS. Regression analysis showed that the ability of insulin to reduce the expression of ANGPTL4 was positively correlated with M-values and inversely correlated with factors linked to the metabolic syndrome. Expression of glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 tended to be higher in YS than in DS or CS, but the expression was not affected by insulin in any of the groups. Our data imply that the insulin-mediated regulation of LPL is not directly linked to the control of glucose turnover by insulin or to ANGPTL4 expression in adipose tissue or plasma. Interestingly, the response of ANGPTL4 expression in adipose tissue to insulin was severely blunted in both DS and CS. 相似文献
48.
NB Eloy N Gonzalez J Van Leene K Maleux H Vanhaeren L De Milde S Dhondt L Vercruysse E Witters R Mercier L Cromer GT Beemster H Remaut MC Van Montagu G De Jaeger PC Ferreira D Inzé 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(34):13853-13858
The anaphase-promoting complex/cyclosome (APC/C) is a large multiprotein E3 ubiquitin ligase involved in ubiquitin-dependent proteolysis of key cell cycle regulatory proteins, including the destruction of mitotic cyclins at the metaphase-to-anaphase transition. Despite its importance, the role of the APC/C in plant cells and the regulation of its activity during cell division remain poorly understood. Here, we describe the identification of a plant-specific negative regulator of the APC/C complex, designated SAMBA. In Arabidopsis thaliana, SAMBA is expressed during embryogenesis and early plant development and plays a key role in organ size control. Samba mutants produced larger seeds, leaves, and roots, which resulted from enlarged root and shoot apical meristems, and, additionally, they had a reduced fertility attributable to a hampered male gametogenesis. Inactivation of SAMBA stabilized A2-type cyclins during early development. Our data suggest that SAMBA regulates cell proliferation during early development by targeting CYCLIN A2 for APC/C-mediated proteolysis. 相似文献
49.
50.