全文获取类型
收费全文 | 8333篇 |
免费 | 553篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 138篇 |
妇产科学 | 104篇 |
基础医学 | 1125篇 |
口腔科学 | 242篇 |
临床医学 | 878篇 |
内科学 | 1628篇 |
皮肤病学 | 130篇 |
神经病学 | 956篇 |
特种医学 | 591篇 |
外科学 | 1499篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 264篇 |
眼科学 | 190篇 |
药学 | 472篇 |
中国医学 | 14篇 |
肿瘤学 | 598篇 |
出版年
2024年 | 6篇 |
2023年 | 85篇 |
2022年 | 142篇 |
2021年 | 406篇 |
2020年 | 206篇 |
2019年 | 256篇 |
2018年 | 319篇 |
2017年 | 237篇 |
2016年 | 363篇 |
2015年 | 392篇 |
2014年 | 476篇 |
2013年 | 499篇 |
2012年 | 781篇 |
2011年 | 717篇 |
2010年 | 429篇 |
2009年 | 380篇 |
2008年 | 583篇 |
2007年 | 507篇 |
2006年 | 444篇 |
2005年 | 426篇 |
2004年 | 346篇 |
2003年 | 327篇 |
2002年 | 231篇 |
2001年 | 37篇 |
2000年 | 27篇 |
1999年 | 41篇 |
1998年 | 39篇 |
1997年 | 30篇 |
1996年 | 9篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1981年 | 4篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1973年 | 3篇 |
1970年 | 7篇 |
1969年 | 5篇 |
1966年 | 4篇 |
排序方式: 共有8926条查询结果,搜索用时 15 毫秒
21.
Expression profiling identifies the CRH/CRH-R1 system as a modulator of neurovascular gene activity.
Jan M Deussing Claudia Kühne Benno Pütz Markus Panhuysen Johannes Breu Mary P Stenzel-Poore Florian Holsboer Wolfgang Wurst 《Journal of cerebral blood flow and metabolism》2007,27(8):1476-1495
Corticotropin-releasing hormone receptor type 1 (CRH-R1)-deficient mice display reduced anxiety-like behavior, a chronic corticosterone deficit, and an impaired neuroendocrine stress response caused by disruption of the hypothalamic-pituitary-adrenocortical (HPA) axis. The molecular substrates and pathways of CRH/CRH-R1-dependent signaling mechanisms underlying the behavioral phenotype as well as the consequences of lifelong glucocorticoid deficit remain largely obscure. To dissect involved neuronal circuitries, we performed comparative expression profiling of brains of CRH-R1 mutant and wild-type mice using our custom made MPIP (Max Planck Institute of Psychiatry) 17k cDNA microarray. Microarray analysis yielded 107 genes showing altered expression levels when comparing CRH-R1 knockout mice with wild-type littermates. A significant proportion of differentially expressed genes was related to control of HPA and hypothalamic-pituitary-thyroid (HPT) axes reflecting not only the disturbance of the HPA axis in CRH-R1 mutant mice but also the interplay of both neuroendocrine systems. The spatial analysis of regulated genes revealed a prevalence for genes expressed in the cerebral microvasculature. This phenotype was confirmed by the successful cross-validation of regulated genes in CRH overexpressing mice. Analysis of the cerebral vasculature of CRH-R1 mutant and CRH overexpressing mice revealed alterations of functional rather than structural properties. A direct role of the CRH/CRH-R1 system was supported by demonstrating Crhr1 expression in the adult murine cerebral vasculature. In conclusion, these data suggest a novel, previously unknown role of the CRH/CRH-R1 system in modulating neurovascular gene expression and function. 相似文献
22.
Florian M Vogt Gerald Antoch Patrick Veit Lutz S Freudenberg Nina Blechschmid Olaf Diersch Andreas Bockisch J?rg Barkhausen Hilmar Kuehl 《Journal of nuclear medicine》2007,48(11):1836-1844
Rimlike contrast enhancement on morphologic imaging and increased tracer uptake on (18)F-FDG PET in the periphery of the necrosis can hamper differentiation of residual tumor from regenerative tissue after radiofrequency ablation of liver lesions. This study used MRI, CT, ultrasound, and (18)F-FDG PET/CT to assess the typical appearance of lesions in nontumorous animal liver tissue after radiofrequency ablation. METHODS: Lesions were created by radiofrequency ablation of normal liver parenchyma in 21 minipigs. Follow-up was performed by 3 contrast-enhanced morphologic modalities-MRI, CT, and ultrasound-and by (18)F-FDG PET/CT immediately, 3 and 10 d, and 1, 2, 3, and 6 mo after radiofrequency ablation. Images were evaluated qualitatively for areas of increased enhancement and regions of elevated tracer uptake. Furthermore, all images were assessed quantitatively by determination of ratios comparing enhancement/tracer uptake in the periphery of the necrosis with enhancement/tracer uptake in normal liver parenchyma. Imaging findings were compared with histopathology findings. RESULTS: Immediately after radiofrequency ablation, no increase in (18)F-FDG uptake was visible, whereas elevated enhancement was noticed in the periphery of the necrosis on all morphologic imaging procedures. At further follow-up, an area of rimlike increase in (18)F-FDG uptake surrounding the necrosis was detected on PET/CT. The rimlike pattern of increased enhancement in the arterial phase was present for all liver lesions on CT, MRI, and ultrasound, especially between day 3 and month 1 after the radiofrequency ablation. Both elevated glucose metabolism and enhancement persisted for 6 mo postinterventionally. Histologic examination showed a hemorrhagic border converting into a regeneration capsule. CONCLUSION: If performed immediately after radiofrequency ablation, (18)F-FDG PET/CT probably has benefits over those of morphologic imaging procedures when assessing liver tissue for residual tumor. Later follow-up may be hampered by visualization of peripheral hyperperfusion and tissue regeneration. Further studies on a patient population are essential. 相似文献
23.
In einer prospektiven Studie zentraler Talusfrakturen wurden radiologische Daten (Nativr?ntgenbild, CT, MRT) auf ihre Korrelation
zum histologischen Befund (Biopsie zum Zeitpunkt der Schraubenentfernung) überprüft. Bei 9 Frakturen an 8 Patienten (Alter
14 – 48 Jahre) handelte es sich um Frakturen des Typs Hawkins I und II je einmal sowie des Typs III viermal; in 3 weiteren
F?llen lagen K?rperfrakturen vor. Innerhalb von 24 h nach dem Unfall wurden 7 Frakturen verschraubt und 2 mit Bohrdr?hten
adaptiert. Das verletzte Bein wurde für 14 – 53 Wochen post trauma vollst?ndig entlastet. Die Beobachtungszeit betrug mit
einer Ausnahme 2 Jahre oder mehr; 4 Patienten zeigten am letzten R?ntgenbild einen intakten Talus, 4 Patienten zeigten partielle
Einbrüche des Talusdoms und in 1 Fall war ein Teileinbruch fraglich. Die histologische Untersuchung (16 – 52 Wochen post trauma)
zeigte in allen F?llen osteozytenfreien origin?ren Knochen mit Anlagerung neuen Knochens in individuell recht unterschiedlichem
Ausma?. Das Hawkins-Zeichen war in 6 F?llen partiell positiv, sowie je einmal positiv und einmal negativ. Im CT konnte sowohl
Dekalzifikation als auch Frakturheilung besser als im R?ntgenbild beobachtet werden. Das MRT-Signal war 5mal normal, 2mal
partiell und einmal komplett pathologisch. Positives Hawkins-Zeichen und normales Signalverhalten sind prognostisch günstig
zu werten. Es kam jedoch in Folge zentraler Talusfraktur auch bei radiologisch günstigem Verlauf zur Osteonekrose wenigstens
von Teilen Talus gefolgt von schleichendem Ersatz. Die offenbar bei jeder zentralen Talusfraktur gest?rte Vaskularisation
wurde von keinem radiologischen Befund einwandfrei reflektiert.
相似文献
24.
Florian A Kagerer Jeff J Summers Winston D Byblow Bruce Taylor 《Movement disorders》2003,18(8):919-927
In 6 patients with Parkinson's disease (PD) and 6 age-matched controls, transcranial magnetic stimulation was applied at 56 regions over the motor cortex and premotor cortex of each hemisphere, with the first dorsal interosseous (FDI) muscle of both hands activated at 15% maximum voluntary contraction during stimulation. For each site, motor evoked potential (MEP) landmarks were recovered, including MEP amplitude, MEP onset latency, and silent period duration. Scaled MEP amplitudes were used to construct individual cortical maps of the FDI muscles. The maps revealed an anterior displacement of the muscle representation in PD patients. This anterior shift over motor cortical areas may reflect increased contributions of corticocortical connections between motor cortex and premotor cortical areas, possibly enhanced by the visual feedback aspect of the task. These alterations may reflect adaptations to the impairments in striatocortical circuits in PD. 相似文献
25.
Florian Kronenberg 《Journal of renal nutrition》2005,15(2):195-203
Patients with nephrotic syndrome (NS) have one of the most pronounced secondary changes in lipoprotein metabolism known, and the magnitude of the changes correlates with the severity of the disease. These changes are of a quantitative as well as a qualitative nature. All apolipoprotein B (apo B)-containing lipoproteins, such as very-low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and lipoprotein(a) [Lp(a)], are elevated in nephrotic syndrome. High-density lipoproteins (HDL) are reported to be unchanged or reduced. In addition to these quantitative changes, the lipoprotein composition is markedly changed, with a higher ratio of cholesterol to triglycerides in the apo B-containing lipoproteins and an increase in the proportion of cholesterol, cholesterol ester, and phospholipids compared with proteins. Also apolipoproteins show major changes, with an increase in apolipoprotein A-I, A-IV, B, C, and E. Particularly the changes in apo C-II, which is an activator of the enzyme lipoprotein lipase (LPL), and apo C-III, an inhibitor of LPL, with an increase of the C-III to C-II ratio, might contribute to the impaired lipoprotein catabolism in NS. The mechanisms for these changes in lipoprotein metabolism are discussed in this review as far as they are known. Furthermore, the tremendous elevations of Lp(a) in nephrotic syndrome and its primary and secondary causes are reviewed. Primary causes became recently apparent by a significantly higher frequency of low-molecular-weight apo(a) phenotypes in patients compared with controls. The secondary causes were shown by an increase of Lp(a) in all apo(a) isoform groups. Because Lp(a) is an LDL-like particle that is usually included in the measured or calculated LDL cholesterol fraction, the influence of the extremely high Lp(a) levels in NS on the measurement of LDL cholesterol is discussed. 相似文献
26.
Elisabeth M Weiss Edith Stadelmann Christian G Kohler Colleen M Brensinger Karen A Nolan Herbert Oberacher Walther Parson Florian Pitterl Harald Niederst?tter Georg Kemmler Hartmann Hinterhuber Josef Marksteiner 《Journal of the International Neuropsychological Society》2007,13(5):881-887
The catechol-O-methyltransferase (COMT) Val158Met polymorphism modulates executive functions and working memory and recent neuroimaging studies implicate an association with emotional processing. We examined the relationship between the COMT Val158Met polymorphism and facial emotion recognition and differentiation in 100 healthy individuals. Compared to Met homozygosity, Val homozygosity was associated with better and faster recognition of negative facial expressions such as anger and sad. Our study provides evidence for a possible influence of the COMT polymorphism on emotion recognition abilities in healthy subjects. Additional research is needed to further define the neurocognitive phenotypes associated with COMT polymorphisms. 相似文献
27.
B Rantner M Pavelka L Posch C Schmidauer G Fraedrich 《European journal of vascular and endovascular surgery》2005,30(1):36-40
PURPOSE: To assess the relationship between outcome of carotid surgery and wait after ischemic stroke. METHODS: We retrospectively analysed data from patients undergoing carotid endarterectomy after ischemic stroke. We investigated the time interval between the event and endarterectomy in relation to surgical results and complications. RESULTS: Between January 2000 and December 2003, 104 patients were scheduled to undergo carotid endarterectomy after a recent stroke. Endarterectomy was performed within 6 h in seven patients (6.7%); within 4 weeks in 29 (27.9%); 4 weeks or more in 62 (59.6%) and six (5.8%) patients received no further therapy. Perioperative complications among patients treated within 4 weeks were 3.4% and were comparable to those treated after 4 weeks (4.8%). However, more than 12% of the patients awaiting operation experienced a new cerebrovascular event (ischemic stroke or carotid occlusion), most of them occurred in the 3rd or 4th week after the initial event. CONCLUSION: Our data indicates, that carotid endarterectomy can be performed with a comparable risk within a short delay after stroke. In addition severe cerebrovascular events occurring within the waiting period may be avoided. 相似文献
28.
29.
Chronic Obstructive Pulmonary Disease (COPD) is one of the major chronic debilitating diseases frequently seen in hospital settings. The disease appears usually after the age of fifty and often predicts a shortened life span. The present paper is a review of the literature relating to the psychological aspects of this disease. The impact on psychosocial coping and adaptation will be discussed, specifically the effects on marital and sexual functioning and the quality of life of the patient. Psycho-social treatment goals useful to the COPD patient and his family will be raised and elaborated on. 相似文献
30.
There is some controversy over the treatment of acromioclavicular injuries. The use of the Rockwood classification as the basis for decisions on whether operative or nonoperative treatment is indicated is discussed critically, and the authors' preferred operative technique is described and illustrated by examples. We treat injuries classified according to the Rockwood classification as types I and II with conservative methods. In type III injuries the patient's age, job and free time activities determine whether or not surgery is indicated. In the case of type IV or type VI injuries we always perform temporary internal fixation of the acromioclavicular joint, using transarticular K-wire fixation or hookplate osteosynthesis. Satisfactory results of both operative and nonoperative treatment are reported in the literature. The authors' own results are presented. 相似文献