全文获取类型
收费全文 | 2486篇 |
免费 | 97篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 67篇 |
儿科学 | 86篇 |
妇产科学 | 8篇 |
基础医学 | 348篇 |
口腔科学 | 104篇 |
临床医学 | 231篇 |
内科学 | 581篇 |
皮肤病学 | 12篇 |
神经病学 | 221篇 |
特种医学 | 103篇 |
外科学 | 346篇 |
综合类 | 9篇 |
一般理论 | 1篇 |
预防医学 | 134篇 |
眼科学 | 28篇 |
药学 | 130篇 |
中国医学 | 1篇 |
肿瘤学 | 188篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 34篇 |
2020年 | 22篇 |
2019年 | 33篇 |
2018年 | 36篇 |
2017年 | 25篇 |
2016年 | 40篇 |
2015年 | 42篇 |
2014年 | 66篇 |
2013年 | 114篇 |
2012年 | 136篇 |
2011年 | 159篇 |
2010年 | 107篇 |
2009年 | 81篇 |
2008年 | 140篇 |
2007年 | 177篇 |
2006年 | 160篇 |
2005年 | 150篇 |
2004年 | 170篇 |
2003年 | 182篇 |
2002年 | 180篇 |
2001年 | 38篇 |
2000年 | 17篇 |
1999年 | 32篇 |
1998年 | 31篇 |
1997年 | 36篇 |
1996年 | 27篇 |
1995年 | 26篇 |
1994年 | 31篇 |
1993年 | 27篇 |
1992年 | 23篇 |
1991年 | 28篇 |
1990年 | 16篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 21篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 14篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1957年 | 2篇 |
排序方式: 共有2598条查询结果,搜索用时 15 毫秒
71.
Miriam S. Nokia Sanna Lensu Juha P. Ahtiainen Petra P. Johansson Lauren G. Koch Steven L. Britton Heikki Kainulainen 《The Journal of physiology》2016,594(7):1855-1873
Key points
- Aerobic exercise, such as running, enhances adult hippocampal neurogenesis (AHN) in rodents.
- Little is known about the effects of high‐intensity interval training (HIT) or of purely anaerobic resistance training on AHN.
- Here, compared with a sedentary lifestyle, we report a very modest effect of HIT and no effect of resistance training on AHN in adult male rats.
- We found the most AHN in rats that were selectively bred for an innately high response to aerobic exercise that also run voluntarily and increase maximal running capacity.
- Our results confirm that sustained aerobic exercise is key in improving AHN.
Abstract
Aerobic exercise, such as running, has positive effects on brain structure and function, such as adult hippocampal neurogenesis (AHN) and learning. Whether high‐intensity interval training (HIT), referring to alternating short bouts of very intense anaerobic exercise with recovery periods, or anaerobic resistance training (RT) has similar effects on AHN is unclear. In addition, individual genetic variation in the overall response to physical exercise is likely to play a part in the effects of exercise on AHN but is less well studied. Recently, we developed polygenic rat models that gain differentially for running capacity in response to aerobic treadmill training. Here, we subjected these low‐response trainer (LRT) and high‐response trainer (HRT) adult male rats to various forms of physical exercise for 6–8 weeks and examined the effects on AHN. Compared with sedentary animals, the highest number of doublecortin‐positive hippocampal cells was observed in HRT rats that ran voluntarily on a running wheel, whereas HIT on the treadmill had a smaller, statistically non‐significant effect on AHN. Adult hippocampal neurogenesis was elevated in both LRT and HRT rats that underwent endurance training on a treadmill compared with those that performed RT by climbing a vertical ladder with weights, despite their significant gain in strength. Furthermore, RT had no effect on proliferation (Ki67), maturation (doublecortin) or survival (bromodeoxyuridine) of new adult‐born hippocampal neurons in adult male Sprague–Dawley rats. Our results suggest that physical exercise promotes AHN most effectively if the exercise is aerobic and sustained, especially when accompanied by a heightened genetic predisposition for response to physical exercise.Abbreviations
- AHN
- adult hippocampal neurogenesis
- BDNF
- brain‐derived neurotrophic factor
- BrdU
- bromodeoxyuridine
- HIT
- high‐intensity interval training
- HRT
- high‐response trainer
- LRT
- low‐response trainer
- RW
- running wheel
- Sed
- sedentary
- TBS
- Tris‐buffered saline
- maximal oxygen uptake
72.
Hämäläinen A Pihlajamäki M Tanila H Hänninen T Niskanen E Tervo S Karjalainen PA Vanninen RL Soininen H 《Neurobiology of aging》2007,28(12):1889-1903
Structural and functional magnetic resonance imaging (fMRI) was performed on 21 healthy elderly controls, 14 subjects with mild cognitive impairment (MCI) and 15 patients with mild Alzheimer's disease (AD) to investigate changes in fMRI activation in relation to underlying structural atrophy. The fMRI paradigm consisted of associative encoding of novel picture-word pairs. Structural analysis of the brain was performed using voxel-based morphometry (VBM) and hippocampal volumetry. Compared to controls, the MCI subjects exhibited increased fMRI responses in the posterior hippocampal, parahippocampal and fusiform regions, while VBM revealed more atrophy in MCI in the anterior parts of the left hippocampus. Furthermore, the hippocampal volume and parahippocampal activation were negatively correlated in MCI, but not in controls or in AD. We suggest that the increased fMRI activation in MCI in the posterior medial temporal and closely connected fusiform regions is compensatory due to the incipient atrophy in the anterior medial temporal lobe. 相似文献
73.
Hellquist A Zucchelli M Kivinen K Saarialho-Kere U Koskenmies S Widen E Julkunen H Wong A Karjalainen-Lindsberg ML Skoog T Vendelin J Cunninghame-Graham DS Vyse TJ Kere J Lindgren CM 《Journal of medical genetics》2007,44(5):314-321
Background
Several members of the GIMAP gene family have been suggested as being involved in different aspects of the immune system in different species. Recently, a mutation in the GIMAP5 gene was shown to cause lymphopenia in a rat model of autoimmune insulin‐dependent diabetes. Thus it was hypothesised that genetic variation in GIMAP5 may be involved in susceptibility to other autoimmune disorders where lymphopenia is a key feature, such as systemic lupus erythematosus (SLE).Material and methods
To investigate this, seven single nucleotide polymorphisms in GIMAP5 were analysed in five independent sets of family‐based SLE collections, containing more than 2000 samples.Result
A significant increase in SLE risk associated with the most common GIMAP5 haplotype was found (OR 1.26, 95% CI 1.02 to 1.54, p = 0.0033). In families with probands diagnosed with trombocytopenia, the risk was increased (OR 2.11, 95% CI 1.09 to 4.09, p = 0.0153). The risk haplotype bears a polymorphic polyadenylation signal which alters the 3′ part of GIMAP5 mRNA by producing an inefficient polyadenylation signal. This results in higher proportion of non‐terminated mRNA for homozygous individuals (p<0.005), a mechanism shown to be causal in thalassaemias. To further assess the functional effect of the polymorphic polyadenylation signal in the risk haplotype, monocytes were treated with several cytokines affecting apoptosis. All the apoptotic cytokines induced GIMAP5 expression in two monocyte cell lines (1.5–6 times, p<0.0001 for all tests).Conclusion
Taken together, the data suggest the role of GIMAP5 in the pathogenesis of SLE. 相似文献74.
Al-Sukhun J Ashammakhi N Penttila H 《The Journal of craniofacial surgery》2007,18(4):781-8; discussion 789-91
The purpose of this study was to evaluate biomechanical loading of the temporomandibular joint when using a biodegradable laminate implant to replace the articular disc and to test the hypothesis that the use of the implant reduces stress distribution in the condyle, implant, and glenoid fossa. A finite element model of a female human mandible, including the temporomandibular joint, which had two standard endosseous implants inserted bilaterally in the premolar region, was constructed from computed tomography scan images using a commercially available finite element software. The disc, condyle, and glenoid fossa were arbitrarily divided into five regions: the anterior, posterior, medial, lateral, and central. The disc was then replaced with a poly-L/DL-lactide biodegradable laminate. The finite element model was then used to predict principal and Von Mises stresses. The use of poly-L/DL-lactide implant resulted in remarkable reduction in Von Mises stresses (approximately threefold) in the anterior, central, and medial regions of the mandibular condyle in comparison with slight to moderate stress reductions in the corresponding regions of the implant and glenoid fossa. The mandibular condyle also demonstrated the largest total displacement in all directions followed by the implant and glenoid fossa. The use of an alloplastic implant such as the bioresorbable, poly-L/DL-lactide laminate to replace the articular disc reduces loading of the mandibular condyle rather than the implant and glenoid fossa. These findings lead to support the hypothesis that the mandibular condyle more likely functions as a shock absorber than the disc. The use of bioresorbable laminate implants might prove an efficient technique to replace the articular disc and promote normal function of the temporomandibular joint. 相似文献
75.
Abhisek Bhattarai Behdad Pouran Janne T. A. Mäkelä Rubina Shaikh Miitu K. M. Honkanen Mithilesh Prakash Heikki Kröger Mark W. Grinstaff Harrie Weinans Jukka S. Jurvelin Juha Töyräs 《Journal of orthopaedic research》2020,38(10):2230-2238
Cationic computed tomography contrast agents are more sensitive for detecting cartilage degeneration than anionic or non-ionic agents. However, osteoarthritis-related loss of proteoglycans and increase in water content contrarily affect the diffusion of cationic contrast agents, limiting their sensitivity. The quantitative dual-energy computed tomography technique allows the simultaneous determination of the partitions of iodine-based cationic (CA4+) and gadolinium-based non-ionic (gadoteridol) agents in cartilage at diffusion equilibrium. Normalizing the cationic agent partition at diffusion equilibrium with that of the non-ionic agent improves diagnostic sensitivity. We hypothesize that this sensitivity improvement is also prominent during early diffusion time points and that the technique is applicable during contrast agent diffusion. To investigate the validity of this hypothesis, osteochondral plugs (d = 8 mm, N = 33), extracted from human cadaver (n = 4) knee joints, were immersed in a contrast agent bath (a mixture of CA4+ and gadoteridol) and imaged using the technique at multiple time points until diffusion equilibrium. Biomechanical testing and histological analysis were conducted for reference. Quantitative dual-energy computed tomography technique enabled earlier determination of cartilage proteoglycan content over single contrast. The correlation coefficient between human articular cartilage proteoglycan content and CA4+ partition increased with the contrast agent diffusion time. Gadoteridol normalized CA4+ partition correlated significantly (P < .05) with Mankin score at all time points and with proteoglycan content after 4 hours. The technique is applicable during diffusion, and normalization with gadoteridol partition improves the sensitivity of the CA4+ contrast agent. 相似文献
76.
Helena Johansson John A Kanis Anders Odén Eugene McCloskey Roland D Chapurlat Claus Christiansen Steve R Cummings Adolfo Diez‐Perez John A Eisman Saeko Fujiwara Claus‐C Glüer David Goltzman Didier Hans Kay‐Tee Khaw Marc‐Antoine Krieg Heikki Kröger Andrea Z LaCroix Edith Lau William D Leslie Dan Mellström L Joseph Melton III Terence W O'Neill Julie A Pasco Jerilynn C Prior David M Reid Fernando Rivadeneira Tjerd van Staa Noriko Yoshimura M Carola Zillikens 《Journal of bone and mineral research》2014,29(1):223-233
Several recent studies suggest that obesity may be a risk factor for fracture. The aim of this study was to investigate the association between body mass index (BMI) and future fracture risk at different skeletal sites. In prospective cohorts from more than 25 countries, baseline data on BMI were available in 398,610 women with an average age of 63 (range, 20–105) years and follow up of 2.2 million person‐years during which 30,280 osteoporotic fractures (6457 hip fractures) occurred. Femoral neck BMD was measured in 108,267 of these women. Obesity (BMI ≥ 30 kg/m2) was present in 22%. A majority of osteoporotic fractures (81%) and hip fractures (87%) arose in non‐obese women. Compared to a BMI of 25 kg/m2, the hazard ratio (HR) for osteoporotic fracture at a BMI of 35 kg/m2 was 0.87 (95% confidence interval [CI], 0.85–0.90). When adjusted for bone mineral density (BMD), however, the same comparison showed that the HR for osteoporotic fracture was increased (HR, 1.16; 95% CI, 1.09–1.23). Low BMI is a risk factor for hip and all osteoporotic fracture, but is a protective factor for lower leg fracture, whereas high BMI is a risk factor for upper arm (humerus and elbow) fracture. When adjusted for BMD, low BMI remained a risk factor for hip fracture but was protective for osteoporotic fracture, tibia and fibula fracture, distal forearm fracture, and upper arm fracture. When adjusted for BMD, high BMI remained a risk factor for upper arm fracture but was also a risk factor for all osteoporotic fractures. The association between BMI and fracture risk is complex, differs across skeletal sites, and is modified by the interaction between BMI and BMD. At a population level, high BMI remains a protective factor for most sites of fragility fracture. The contribution of increasing population rates of obesity to apparent decreases in fracture rates should be explored. © 2014 American Society for Bone and Mineral Research. 相似文献
77.
78.
Puumala hantavirus (PUUV), carried and spread by the bank vole (Myodes glareolus), causes a mild form of hemorrhagic fever with renal syndrome (HFRS) called nephropathia epidemica (NE). Acute high fever, acute kidney injury (AKI), thrombocytopenia, and hematuria are typical features of this syndrome. In addition, headache, blurred vision, insomnia, vertigo, and nausea are commonly associated with the disease. This review explores the mechanisms and presentations of ocular and central nervous system involvement in acute NE. 相似文献
79.
80.