全文获取类型
收费全文 | 120321篇 |
免费 | 43156篇 |
国内免费 | 221篇 |
专业分类
耳鼻咽喉 | 1918篇 |
儿科学 | 5186篇 |
妇产科学 | 1264篇 |
基础医学 | 23391篇 |
口腔科学 | 5981篇 |
临床医学 | 15794篇 |
内科学 | 31303篇 |
皮肤病学 | 8548篇 |
神经病学 | 17665篇 |
特种医学 | 4042篇 |
外科学 | 19909篇 |
综合类 | 204篇 |
一般理论 | 42篇 |
预防医学 | 6348篇 |
眼科学 | 2365篇 |
药学 | 8707篇 |
中国医学 | 1041篇 |
肿瘤学 | 9990篇 |
出版年
2023年 | 202篇 |
2022年 | 310篇 |
2021年 | 1782篇 |
2020年 | 5382篇 |
2019年 | 11274篇 |
2018年 | 10688篇 |
2017年 | 11902篇 |
2016年 | 12754篇 |
2015年 | 12632篇 |
2014年 | 12783篇 |
2013年 | 13667篇 |
2012年 | 6312篇 |
2011年 | 6393篇 |
2010年 | 10383篇 |
2009年 | 6702篇 |
2008年 | 4690篇 |
2007年 | 3625篇 |
2006年 | 3553篇 |
2005年 | 3487篇 |
2004年 | 3270篇 |
2003年 | 3188篇 |
2002年 | 3337篇 |
2001年 | 1315篇 |
2000年 | 1084篇 |
1999年 | 827篇 |
1998年 | 722篇 |
1997年 | 563篇 |
1996年 | 500篇 |
1995年 | 462篇 |
1994年 | 382篇 |
1993年 | 365篇 |
1992年 | 297篇 |
1991年 | 288篇 |
1990年 | 252篇 |
1989年 | 240篇 |
1988年 | 266篇 |
1987年 | 206篇 |
1986年 | 195篇 |
1985年 | 219篇 |
1984年 | 236篇 |
1983年 | 215篇 |
1982年 | 265篇 |
1981年 | 206篇 |
1980年 | 174篇 |
1978年 | 173篇 |
1933年 | 174篇 |
1932年 | 186篇 |
1931年 | 170篇 |
1930年 | 173篇 |
1928年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Human Papillomaviruses in Transplant-Associated Skin Cancers 总被引:1,自引:0,他引:1
Eggert Stockfleth MD Ingo Nindl Ph D Wolfram Sterry MD Claas Ulrich MD Tobias Schmook MD Thomas Meyer Ph D 《Dermatologic surgery》2004,30(4P2):604-609
Background. Human papillomavirus (HPV) infection has been suggested to be involved in the development of nonmelanoma skin cancer, the most common malignancy after solid-organ transplantation.
Objective. The objective of this study was to analyze the prevalence of different HPV types in squamous cell carcinomas (SCC) and basal cell carcinomas (BCC) of transplant recipients and nonimmunosuppressed patients.
Methods. To include the complete spectrum of HPV types in skin lesions, a comprehensive polymerase chain reaction assay with five different primer combinations was used.
Results. For SCC, HPV DNA was detected more frequently in tumors of transplant recipients (12/16, 75%) than of nonimmunosuppressed patients (7/19, 37%). In contrast, the HPV detection rate was similar in BCC specimens (4/8 or 50% in transplanted patients; 27/56 or 48% in nonimmunosupressed patients). Overall, 22 different HPV types were identified. HPV types 5 and 8 were detected predominately in SCC from transplant recipients. The amount of viral DNA was slightly higher in SCC of transplanted than in nonimmunosuppressed patients, but much lower than in both cutaneous and genital warts.
Conclusions. Cutaneous infections with HPV5 and HPV8 may represent an increased risk for SCC development in transplant recipients. The mechanisms by which these viruses may contribute to skin cancer development still remain unclear. 相似文献
Objective. The objective of this study was to analyze the prevalence of different HPV types in squamous cell carcinomas (SCC) and basal cell carcinomas (BCC) of transplant recipients and nonimmunosuppressed patients.
Methods. To include the complete spectrum of HPV types in skin lesions, a comprehensive polymerase chain reaction assay with five different primer combinations was used.
Results. For SCC, HPV DNA was detected more frequently in tumors of transplant recipients (12/16, 75%) than of nonimmunosuppressed patients (7/19, 37%). In contrast, the HPV detection rate was similar in BCC specimens (4/8 or 50% in transplanted patients; 27/56 or 48% in nonimmunosupressed patients). Overall, 22 different HPV types were identified. HPV types 5 and 8 were detected predominately in SCC from transplant recipients. The amount of viral DNA was slightly higher in SCC of transplanted than in nonimmunosuppressed patients, but much lower than in both cutaneous and genital warts.
Conclusions. Cutaneous infections with HPV5 and HPV8 may represent an increased risk for SCC development in transplant recipients. The mechanisms by which these viruses may contribute to skin cancer development still remain unclear. 相似文献
992.
Axel Stäbler M.D. Richard G. H. Baumeister M.D. Ulrike Szeimies Ulrich Fink M.D. Hermann Berger M.D. 《Skeletal radiology》1994,23(2):103-106
Post-traumatic ulnar carpal translocation is a rare, severe ligamentous injury to the wrist. Radiologic findings include widening of the radiocarpal joint space at the radial styloid process and ulnar displacement of the carpus. Less than 50% of the lunate articulates with the radius in the neutral position; the lunate is tilted dorsally with palmar subluxation due to a ruptured radioscapholunate (RSL) ligament. This malposition should be called rotatory palmar subluxation of the lunate (RPSL), by analogy to rotatory subluxation of the scaphoid (RSS). In contrast to dorsiflexed intercalated segment instability (DISI), in RPSL the RSL ligament is ruptured and, in the majority of cases, the scapholunate ligament remains intact. A prompt diagnosis should lead to successful treatment. 相似文献
993.
Eight brains from patients with a mean age of 82 years showing clinical and neuropathological manifestations of senile dementia of the Alzheimer type (SDAT) and 6 control brains from individuals with a mean age of 89 years who were mentally normal or who had minimal senile impairment of memory, were selected by a rigorous elimination procedure for final evaluation from a total of 26 brains. Using an optical electronic image-analysis system, stereological measurements were made of the size and number of senile plaques, and of nerve cell area, capillary diameter, capillary length and intercapillary distance in the medial frontal gyrus, medial temporal gyrus and precentral gyrus. The number and size of senile plaques did not correlate with any of the other parameters measured, whereas Mountjoy et al. (1983) found a correlation between neuronal count and plaque count. In SDAT the cerebral cortex displayed significant atrophy of the neuronal perikarya (mean decrease approximately 50%). The greatest decrease in nerve cell area (55%) was seen in layers III and IV of the medial temporal cortex. Stereological measurements on the capillary network revealed only moderate neuropil shrinkage. Capillary volume was on average 30% greater in SDAT as a result of a decrease in intercapillary distance. These findings indicate that nerve cell shrinkage is a characteristic indicator of senile dementia. Neuropil atrophy may be of secondary importance. 相似文献
994.
B O Lindhardt J Gerstoft K Ulrich K Bentzen E Scheibel J Dalsg?rd Nielsen E Dickmeiss 《Scandinavian journal of haematology》1985,35(4):379-385
18 out of 40 healthy Danish type A haemophiliacs had antibodies against HTLV-III as measured by an enzyme linked immunosorbent assay (ELISA). The overall seropositivity was 45%. A significant positive correlation was found between seropositivity and total lifetime dose of factor VIII and the age of the patients. 63% and 79% of the patients predominantly treated with commercial American and European preparations, respectively, had antibodies, compared with 11% among patients predominantly treated with Danish cryoprecipitate. Patients exclusively treated with preparations from a single source in the year prior to investigation showed 69% seropositivity when treated with American and European preparations. None of the patients treated with Danish cryoprecipitates prepared from voluntary Danish donors had antibodies. No difference between seropositive and seronegative groups was found in total lymphocyte count, leu 2+ cells, leu 3+ cells and leu 2+/leu 3+ ratio but the seropositive group had significantly higher total IgG and lower skin test score. It is concluded that treatment with local European preparation carries less risk of HTLV-III infection compared with commercial preparations from either the USA or Europe. The results also suggested that T-cell subset alterations among haemophiliacs are not primarily due to HTLV-III infection. 相似文献
995.
Brain‐derived neurotrophic factor prevents dendritic retraction of adult mouse retinal ganglion cells 下载免费PDF全文
Kate E. Binley Wai S. Ng Yves‐Alain Barde Bing Song James E. Morgan 《The European journal of neuroscience》2016,44(3):2028-2039
We used cultured adult mouse retinae as a model system to follow and quantify the retraction of dendrites using diolistic labelling of retinal ganglion cells (RGCs) following explantation. Cell death was monitored in parallel by nuclear staining as ‘labelling’ with RGC and apoptotic markers was inconsistent and exceedingly difficult to quantify reliably. Nuclear staining allowed us to delineate a lengthy time window during which dendrite retraction can be monitored in the absence of RGC death. The addition of brain‐derived neurotrophic factor (BDNF) produced a marked reduction in dendritic degeneration, even when application was delayed for 3 days after retinal explantation. These results suggest that the delayed addition of trophic factors may be functionally beneficial before the loss of cell bodies in the course of conditions such as glaucoma. 相似文献
996.
Perceived state of self during motion can differentially modulate numerical magnitude allocation 下载免费PDF全文
Q. Arshad Y. Nigmatullina R. E. Roberts U. Goga M. Pikovsky S. Khan R. Lobo A.‐S. Flury V. E. Pettorossi R. Cohen‐Kadosh P. A. Malhotra A. M. Bronstein 《The European journal of neuroscience》2016,44(6):2369-2374
Although a direct relationship between numerical allocation and spatial attention has been proposed, recent research suggests that these processes are not directly coupled. In keeping with this, spatial attention shifts induced either via visual or vestibular motion can modulate numerical allocation in some circumstances but not in others. In addition to shifting spatial attention, visual or vestibular motion paradigms also (i) elicit compensatory eye movements which themselves can influence numerical processing and (ii) alter the perceptual state of ‘self’, inducing changes in bodily self‐consciousness impacting upon cognitive mechanisms. Thus, the precise mechanism by which motion modulates numerical allocation remains unknown. We sought to investigate the influence that different perceptual experiences of motion have upon numerical magnitude allocation while controlling for both eye movements and task‐related effects. We first used optokinetic visual motion stimulation (OKS) to elicit the perceptual experience of either ‘visual world’ or ‘self’‐motion during which eye movements were identical. In a second experiment, we used a vestibular protocol examining the effects of perceived and subliminal angular rotations in darkness, which also provoked identical eye movements. We observed that during the perceptual experience of ‘visual world’ motion, rightward OKS‐biased judgments towards smaller numbers, whereas leftward OKS‐biased judgments towards larger numbers. During the perceptual experience of ‘self‐motion’, judgments were biased towards larger numbers irrespective of the OKS direction. Contrastingly, vestibular motion perception was found not to modulate numerical magnitude allocation, nor was there any differential modulation when comparing ‘perceived’ vs. ‘subliminal’ rotations. We provide a novel demonstration that numerical magnitude allocation can be differentially modulated by the perceptual state of self during visual but not vestibular mediated motion. 相似文献
997.
Differences in spatial and temporal frequency interactions between central and peripheral parts of the feline area 18 下载免费PDF全文
Chunzhen Zhao Ryosuke Hata Jun‐ya Okamura Gang Wang 《The European journal of neuroscience》2016,44(8):2635-2645
The visual system demonstrates significant differences in information processing abilities between the central and peripheral parts of the visual field. Optical imaging based on intrinsic signals was used to investigate the difference in stimulus spatial and temporal frequency interactions related to receptive field eccentricity in the cat area 18. Changing either the spatial or the temporal frequency of grating stimuli had a significant impact on responses in the cortical areas corresponding to the centre of the visual field and more peripheral parts at 10 degrees eccentricity. The cortical region corresponding to the centre of the gaze was tuned to 0.4 cycles per degree (c/deg) for spatial frequency and 2 Hz for temporal frequency. In contrast, the cortical region corresponding to the periphery of the visual field was tuned to a lower spatial frequency of 0.15 c/deg and a higher temporal frequency of 4 Hz. Interestingly, when we simultaneously changed both the spatial frequency and the temporal frequency of the grating stimuli, the responses were significantly different from those estimated with an assumption of independence between the spatial and temporal frequency in the cortical region corresponding to the periphery of the visual field. However, in the cortical area corresponding to the centre of the gaze, spatial frequency showed significant independence from temporal frequency. These properties support the notion of relative specialization of visual information processing for peripheral representations in cortical areas. 相似文献
998.
999.
1000.
Epidemiology,pathophysiology and putative genetic basis of carbamazepine‐ and oxcarbazepine‐induced hyponatremia 下载免费PDF全文
B. Berghuis G.‐J. de Haan M. P. H. van den Broek J. W. Sander D. Lindhout B. P. C. Koeleman 《European journal of neurology》2016,23(9):1393-1399
The use of carbamazepine (CBZ) and oxcarbazepine (OXC) as first‐line antiepileptic drugs in the treatment of focal epilepsy is limited by hyponatremia, a known adverse effect. Hyponatremia occurs in up to half of people taking CBZ or OXC and, although often assumed to be asymptomatic, it can lead to symptoms ranging from unsteadiness and mild confusion to seizures and coma. Hyponatremia is probably due to the antidiuretic properties of CBZ and OXC that are, at least partly, explained by stimulation of the vasopressin 2 receptor/aquaporin 2 pathway. No known genetic risk variants for CBZ‐ and OXC‐induced hyponatremia exist, but likely candidate genes are part of the vasopressin water reabsorption pathway. 相似文献