全文获取类型
收费全文 | 2933篇 |
免费 | 95篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 64篇 |
妇产科学 | 85篇 |
基础医学 | 363篇 |
口腔科学 | 65篇 |
临床医学 | 315篇 |
内科学 | 805篇 |
皮肤病学 | 28篇 |
神经病学 | 286篇 |
特种医学 | 73篇 |
外科学 | 378篇 |
综合类 | 10篇 |
一般理论 | 5篇 |
预防医学 | 257篇 |
眼科学 | 41篇 |
药学 | 139篇 |
中国医学 | 1篇 |
肿瘤学 | 102篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 37篇 |
2020年 | 24篇 |
2019年 | 26篇 |
2018年 | 32篇 |
2017年 | 29篇 |
2016年 | 45篇 |
2015年 | 51篇 |
2014年 | 55篇 |
2013年 | 143篇 |
2012年 | 171篇 |
2011年 | 163篇 |
2010年 | 96篇 |
2009年 | 111篇 |
2008年 | 193篇 |
2007年 | 197篇 |
2006年 | 183篇 |
2005年 | 234篇 |
2004年 | 204篇 |
2003年 | 190篇 |
2002年 | 192篇 |
2001年 | 42篇 |
2000年 | 26篇 |
1999年 | 34篇 |
1998年 | 41篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 31篇 |
1993年 | 31篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 13篇 |
1985年 | 34篇 |
1984年 | 23篇 |
1983年 | 30篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1974年 | 14篇 |
1971年 | 6篇 |
排序方式: 共有3039条查询结果,搜索用时 15 毫秒
81.
Esa Pekkala Eeva-Liisa Hietala Matti Puukka Markku Larmas 《Acta odontologica Scandinavica》2013,71(4):155-159
Previous studies show that a high sucrose diet reduces the rate of primary dentinogenesis and increases dental caries, although their cause-effect relationship is still obscure. The purpose of this study was to explore whether the effect of sucrose load on the dentinogenesis and dental caries of young rat molars is mediated by systemic (intragastric) or by systemic and local (dietary) factors. At weaning (19 days), animals were randomized into the control, intragastric sucrose, and dietary sucrose groups for 4 weeks. The areas of dentin appositions and dentinal caries lesions were measured planimetrically. Caries was also determined with Shiff's staining and the width of predentin by histology. Urinary Ca, K, and Na levels were measured by flame photometry, urinary P levels using an UV method, and serum insulin levels using radioimmunoassay. Systemic and local sucrose load reduced dentin appositions and intragastric sucrose increased urinary Ca excretion. No differences in the width of predentin were noticed. Only dietary sucrose enhanced the occurrence and progression of caries. The present findings show that sucrose load reduces dentinogenesis by impairing the synthesis of dentin matrix, but also point out the crucial importance of the local sucrose challenge in the initiation of dental caries. 相似文献
82.
Sandra Merscher-Gomez Johanna Guzman Christopher E. Pedigo Markku Lehto Robier Aguillon-Prada Armando Mendez Mariann I. Lassenius Carol Forsblom TaeHyun Yoo Rodrigo Villarreal Dony Maiguel Kevin Johnson Ronald Goldberg Viji Nair Ann Randolph Matthias Kretzler Robert G. Nelson George W. Burke III Per-Henrik Groop Alessia Fornoni the FinnDiane Study Group 《Diabetes》2013,62(11):3817-3827
Diabetic kidney disease (DKD) remains the most common cause of end-stage kidney disease despite multifactorial intervention. We demonstrated that increased cholesterol in association with downregulation of ATP-binding cassette transporter ABCA1 occurs in normal human podocytes exposed to the sera of patients with type 1 diabetes and albuminuria (DKD+) when compared with diabetic patients with normoalbuminuria (DKD−) and similar duration of diabetes and lipid profile. Glomerular downregulation of ABCA1 was confirmed in biopsies from patients with early DKD (n = 70) when compared with normal living donors (n = 32). Induction of cholesterol efflux with cyclodextrin (CD) but not inhibition of cholesterol synthesis with simvastatin prevented podocyte injury observed in vitro after exposure to patient sera. Subcutaneous administration of CD to diabetic BTBR (black and tan, brachiuric) ob/ob mice was safe and reduced albuminuria, mesangial expansion, kidney weight, and cortical cholesterol content. This was followed by an improvement of fasting insulin, blood glucose, body weight, and glucose tolerance in vivo and improved glucose-stimulated insulin release in human islets in vitro. Our data suggest that impaired reverse cholesterol transport characterizes clinical and experimental DKD and negatively influences podocyte function. Treatment with CD is safe and effective in preserving podocyte function in vitro and in vivo and may improve the metabolic control of diabetes.Diabetic kidney disease (DKD) is responsible for nearly half of the incidents of end-stage kidney disease in the U.S. (1), yet our current understanding of the pathophysiological processes responsible for DKD has led to limited improvements in patient outcomes. Multifactorial intervention reduces the rate of progression of DKD but does not prevent end-stage kidney disease in type 1 (T1D) or type 2 diabetes (T2D) (2,3). A key factor for this translation gap is the current lack of adequate mechanistic insight into DKD in humans.The kidney glomerulus is a highly specialized structure that ensures the selective ultrafiltration of plasma so that essential proteins are retained in the blood (4). Podocytes are glomerular epithelial cells that contribute to the glomerular filtration barrier through a tight regulation of actin cytoskeleton remodeling (4). Currently, the diagnosis of DKD relies on the detection of microalbuminuria (5). However, a growing body of evidence suggests that key histological lesions precede the development of albuminuria (6,7); among them, decreased podocyte number (podocytopenia) has been described as an independent predictor of DKD progression (8–12). Although we have previously shown that podocyte insulin resistance and susceptibility to apoptosis is already present at the time of onset of microalbuminuria in experimental models of DKD, the cause of podocyte injury in early DKD remains unknown (13).We used a previously established cell-based assay in which differentiated human podocytes are exposed to 4% patient sera for 24 h (14) to identify new pathways and targets in DKD. Podocytes exposed to the sera of patients with DKD showed increased cholesterol accumulation in association with downregulation of ATP-binding cassette transporter 1 (ABCA1) expression that was independent of circulating cholesterol.ABCA1 is a major regulator of cellular cholesterol homeostasis by mediating efflux to lipid-poor apolipoprotein acceptors in the bloodstream (15). ABCA1 genetic variants are strongly associated with the risk of coronary artery disease (16). Furthermore, the capacity of patient sera to induce ABCA1-mediated cholesterol efflux in macrophages is impaired in patients with T2D and incipient or overt nephropathy (17). Excessive cholesterol accumulation has been described in glomeruli of rodent models of T1D and T2D (18–20) and may contribute to DKD development and progression. Finally, inactivating mutations of ABCA1 result in Tangier disease, which causes premature atherosclerosis and proteinuria (21).Although interventions that increase ABCA1 expression (such as liver X receptor agonists) may be beneficial in DKD, they have a relatively high incidence of adverse events (22) as well as intrinsic lipogenic effects (23). We used β-cyclodextrins, cyclic oligosaccharides consisting of seven β(1-4)-glucopyranose rings, to remove cholesterol from differentiated human podocytes in vitro and from diabetic animals in vivo. The exact mechanism by which cyclodextrins (CDs) remove cholesterol from cells is not completely understood, but the formation of cholesterol/CD inclusion complexes at the membrane surface plays an important role in this process (24).We hypothesized that 2-hydroxypropyl-β-cyclodextrin, which was recently approved by the U.S. Food and Drug Administration (FDA) for the cure of Niemann-Pick disorder (25,26), would be an effective way to sequester cholesterol and to protect podocytes from cholesterol-dependent damage in DKD in vivo and in vitro. 相似文献
83.
Sipilä K Kähönen M Salomaa V Päivänsalo M Karanko H Varpula M Jula A Kaaja R Kesäniemi YA Reunanen A Moilanen L 《Acta diabetologica》2012,49(3):215-223
The association between diabetes and subclinical atherosclerosis is well established. The effect of non-diabetic glucose intolerance on early atherosclerosis is not as straightforward, and the data regarding sex-related differences in this matter are limited. Therefore, our aim was to investigate these associations in men and women separately. We studied 1,304 Finnish men and women over 45?years of age who participated in the Finnish Health 2000 Survey. Ultrasonically determined carotid artery intima-media thickness and elasticity were used as markers of early atherosclerosis. Glucose tolerance was categorized according to the American Diabetes Association criteria for diabetes mellitus. Age-adjusted means for carotid artery intima-media thickness and elasticity indices were significantly (P?<?0.05) associated with glucose tolerance status in both sexes. There was a trend of increasing early atherosclerosis with the worsening of glucose tolerance in men and women. These associations were weakened in both sexes after further adjustments for other cardiovascular risk factors. In women, but not in men, significant (P?<?0.05) associations between glucose tolerance status and carotid artery elasticity were seen even after these further adjustments. Diabetes and non-diabetic glucose intolerance are associated with increased early carotid atherosclerosis compared with normal glucose tolerance in both sexes. Our results suggest that women with glucose intolerance may be in greater risk than men. 相似文献
84.
Ukkola A Mäki M Kurppa K Collin P Huhtala H Kekkonen L Kaukinen K 《European Journal of Internal Medicine》2012,23(4):384-388
ObjectiveThe clinical presentation of coeliac disease has changed and patients are often overweight at diagnosis. There is concern that patients might gain further weight while on a gluten-free diet (GFD). The aim of the study was to evaluate the impact of a GFD on the body mass index (BMI) in a nationwide cohort of coeliac patients and to determine variables predictive of favourable or unfavourable BMI changes.MethodsWe prospectively investigated weight and disease-related issues in 698 newly detected adults diagnosed due to classical or extraintestinal symptoms or by screening. BMI at diagnosis and after one year on a GFD were assessed and compared with that in the general population.ResultsAt diagnosis, 4% of subjects were underweight, 57% normal, 28% overweight and 11% obese. On a GFD, 69% of underweight patients gained and 18% of overweight and 42% of obese lost weight; in the rest BMI remained stable. Changes were similar in both symptom- and screen-detected patients. The coeliac group had a more favourable BMI pattern than the general population. Favourable BMI changes were associated with subjects' self-rated expertise on GFD and young age at diagnosis, but not dietary counselling received.ConclusionsBMI improved similarly in screen- and symptom-detected coeliac disease patients on a GFD. 相似文献
85.
Greve AM Olsen MH Bella JN Lønnebakken MT Gerdts E Okin PM Palmieri V Boman K Nieminen MS Omvik P Dahlöf B Devereux RB Wachtell K 《American journal of hypertension》2012,25(9):1017-1023
BackgroundPharmaceutical differences in central hemodynamics might influence cardiac response to antihypertensive treatment despite similar lowering of brachial blood pressure (BP).MethodsData from all patients with at least two echocardiographic examinations in the Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) echocardiographic substudy (n = 801); high-risk patients on losartan- vs. atenolol-based antihypertensive therapy. Echocardiography was performed annually for 4 years to measure stroke index (SI), heart rate, cardiac index (CI), conduit artery stiffness assessed as pulse pressure/stroke index (PP/SI) and total peripheral resistance index (TPRI).ResultsAtenolol- and losartan-based therapy reduced BP similarly (cumulative difference in mean brachial blood pressure 0.3 mm Hg, P = 0.65). After 4 years the cumulative means of SI and heart rate were 1.8 ml/m(2) higher and 5.7 beats/min lower on atenolol-based treatment, respectively (both P < 0.001). This kept CI below baseline in atenolol-treated patients, whereas in the losartan group CI was unchanged from baseline throughout the study. TPRI was decreased more and remained lower in the losartan group (cumulative difference in mean TPRI 287 dynes/sec(-5)/cm/m(2), P < 0.001). These findings partly explained univariate differences in systolic- and diastolic function indices between the two treatments; fully adjusted losartan was only associated with a smaller left atrial diameter (cumulative mean difference 0.07 cm; 95% confidence intervals, -0.13 to -0.01, P = 0.03).ConclusionsContrasting hemodynamics impacted cardiac response to similar reductions in brachial BP on losartan- vs. atenolol-based therapy. The similar reduction of PP/SI suggests that the antihypertensive regimens used in the LIFE study had comparable effects on arterial stiffness (LIFE study; NCT00338260)American Journal of Hypertension, (2012); doi:10.1038/ajh.2012.81. 相似文献
86.
87.
Virve Koljonen Markku Laitila Harri Sintonen Risto P. Roine 《Burns : journal of the International Society for Burn Injuries》2013
Objective
Health-related quality of life (HRQoL) has gained increasing interest as an important indicator of adaptation after a burn injury. Our objective was to compare HRQoL of medium severity hospitalized burn victims with no need for intensive care treatment with that of the general population.Methods
The 15D HRQoL questionnaire at discharge, and 6, 12 and 24 months thereafter.Results
44 patients filled in the baseline questionnaire between June 2007 and December 2009. At discharge the mean (SD) HRQoL score (on a scale of 0–1) of the patients was worse in comparison with that of the general population (0.839 (0.125) vs. 0.936 (0.071)), p < 0.001. The most striking differences (p < 0.001) were seen on the dimensions of sleeping, usual activities, discomfort and symptoms, and sexual activity. At the 2-year follow-up the mean HRQoL score had increased from 0.835 (0.121) to 0.856 (0.149), but the difference was not statistically significant. Of the dimensions, moving and usual activities improved statistically significantly.Conclusions
HRQoL of patients hospitalized for treatment of burns is, at discharge, compromised compared with that of the general population. During follow-up HRQoL showed slight improvement but remained at a clearly lower level. 相似文献88.
Juho-Antti Junno Markus Paananen Jaro Karppinen Tuija Tammelin Jaakko Niinimäki Eveliina Lammentausta Markku Niskanen Miika T. Nieminen Marjo-Riitta Järvelin Jani Takatalo Osmo Tervonen Juha Tuukkanen 《The spine journal》2013,13(2):184-189
Background contextReduced vertebral strength is a clear risk factor for vertebral fractures. Men and women with vertebral fractures often have reduced vertebral size and bone mineral density (BMD). Vertebral strength is controlled by both genetic and developmental factors. Malnutrition and low levels of physical activity are commonly considered to result in reduced bone size during growth. Several studies have also demonstrated the general relationship between BMD and physical activity in the appendicular skeleton.PurposeIn this study, we wanted to clarify the role of physical activity on vertebral bodies. Vertebral dimensions appear to generally be less pliant than long bones when lifetime changes occur. We wanted to explore the association between physical activity during late adolescence and vertebral strength parameters such as cross-sectional size and BMD.Study designThe association between physical activity and vertebral strength was explored by measuring vertebral strength parameters and defining the level of physical activity during adolescence.Patient sampleThe study population consisted of 6,928 males and females who, at 15 to 16 and 19 years of age, responded to a mailed questionnaire inquiring about their physical activity. A total of 558 individuals at the mean age of 21 years underwent magnetic resonance imaging (MRI) scans.MethodsWe measured the dimensions of the fourth lumbar vertebra from the MRI scans of the Northern Finland Birth Cohort 1986 and performed T2* relaxation time mapping, reflective of BMD. Vertebral strength was based on these two parameters. We analyzed the association of physical activity on vertebral strength using the analysis of variance.Results and conclusionsWe observed no association between the level of physical activity during late adolescence and vertebral strength at 21 years. 相似文献
89.
Pia Pajunen Mikko Syvänne Graciela Castro Markku S. Nieminen Marja-Riitta Taskinen 《Scandinavian cardiovascular journal : SCJ》2013,47(2):96-100
Objective - To investigate the relation between severity and extent of coronary artery disease (CAD) and in vitro cholesterol efflux capacity. Design - This study consisted of 46 type 2 diabetic, and 42 nondiabetic men undergoing coronary angiography. Quantitative coronary angiography was used to estimate the severity, extent, and overall "atheroma burden" of CAD. The capacity of patient plasma to induce cholesterol efflux from cultured Fu5AH rat hepatoma cells was measured in vitro. Results - In the combined study population (n = 88), there was a significant inverse correlation between efflux and global atheroma burden (r = -0.23, p < 0.05). In the diabetic group, the global atheroma burden index was independently associated both with cholesterol efflux and with LpA-I levels. However, in the nondiabetic CAD group this association was lost when efflux and LpA-I levels were included in the same model. Conclusion - The present study demonstrated that efflux capacity was inversely associated with the severity and extent of CAD. In the diabetic group this association was independent of LpA-I levels, suggesting impaired antiatherogenic potential of these particles in type 2 diabetic patients. 相似文献
90.
Mäki M Aine L 《Journal of the American Dental Association (1939)》2012,143(7):730; author reply 730, 732