全文获取类型
收费全文 | 4246篇 |
免费 | 234篇 |
国内免费 | 54篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 67篇 |
妇产科学 | 81篇 |
基础医学 | 495篇 |
口腔科学 | 64篇 |
临床医学 | 320篇 |
内科学 | 1446篇 |
皮肤病学 | 69篇 |
神经病学 | 504篇 |
特种医学 | 199篇 |
外科学 | 570篇 |
综合类 | 20篇 |
预防医学 | 114篇 |
眼科学 | 44篇 |
药学 | 198篇 |
中国医学 | 16篇 |
肿瘤学 | 313篇 |
出版年
2023年 | 33篇 |
2022年 | 72篇 |
2021年 | 119篇 |
2020年 | 87篇 |
2019年 | 93篇 |
2018年 | 132篇 |
2017年 | 110篇 |
2016年 | 126篇 |
2015年 | 132篇 |
2014年 | 186篇 |
2013年 | 260篇 |
2012年 | 357篇 |
2011年 | 340篇 |
2010年 | 211篇 |
2009年 | 195篇 |
2008年 | 289篇 |
2007年 | 281篇 |
2006年 | 257篇 |
2005年 | 298篇 |
2004年 | 259篇 |
2003年 | 189篇 |
2002年 | 157篇 |
2001年 | 23篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 22篇 |
1997年 | 29篇 |
1996年 | 25篇 |
1995年 | 26篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1970年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有4534条查询结果,搜索用时 15 毫秒
11.
Macchi C Popolizio A Casamorata F Bicchi S Pieroni A Molino Lova R Miniati B Gulisano M Catini C Conti AA Gensini GF 《Italian journal of anatomy and embryology = Archivio italiano di anatomia ed embriologia》2002,107(2):93-97
Fifty-four subjects, aged between 20 and 35 years, divided into two subgroups, respectively 30 healthy subjects (17 males and 13 females) and 24 subjects with "gonalgia sine materia" (13 males and 11 females) underwent isokinetic exercise test in order to compare their dominant limb with the not dominant one as regard as the strength of extensor and flexor muscles of the knee. No statistically significant difference was found in any of the studied parameters in the comparison between the dominant limb and the not dominant one, both within the subgroup of healthy subjects and within the subgroup of subjects with "gonalgia sine materia". Authors conclude that psychological features may play a preeminent role in the genesis, as well as in the maintenance of "gonalgia sine materia", thus confirming previous data available in medical literature. 相似文献
12.
13.
D'Adamo P Welzl H Papadimitriou S Raffaele di Barletta M Tiveron C Tatangelo L Pozzi L Chapman PF Knevett SG Ramsay MF Valtorta F Leoni C Menegon A Wolfer DP Lipp HP Toniolo D 《Human molecular genetics》2002,11(21):2567-2580
Non-specific mental retardation (NSMR) is a common human disorder characterized by mental handicap as the only clinical symptom. Among the recently identified MR genes is GDI1, which encodes alpha Gdi, one of the proteins controlling the activity of the small GTPases of the Rab family in vesicle fusion and intracellular trafficking. We report the cognitive and behavioral characterization of mice carrying a deletion of Gdi1. The Gdi1-deficient mice are fertile and anatomically normal. They appear normal also in many tasks to assess spatial and episodic memory and emotional behavior. Gdi1-deficient mice are impaired in tasks requiring formation of short-term temporal associations, suggesting a defect in short-term memory. In addition, they show lowered aggression and altered social behavior. In mice, as in humans, lack of Gdi1 spares most central nervous system functions and preferentially impairs only a few forebrain functions required to form temporal associations. The general similarity to human mental retardation is striking, and suggests that the Gdi1 mutants may provide insights into the human defect and into the molecular mechanisms important for development of cognitive functions. 相似文献
14.
Radiochromic film dosimetry of a low energy proton beam 总被引:1,自引:0,他引:1
Piermattei A Miceli R Azario L Fidanzio A delle Canne S De Angelis C Onori S Pacilio M Petetti E Raffaele L Sabini MG 《Medical physics》2000,27(7):1655-1660
In this work some dosimetric characteristics of MD-55-2 GafChromic films were studied in a low energy proton beam (21.5 MeV) directly in a water phantom. The nonlinearity of the optical density was quantified by a factor P(lin). A correction factor P(en), that accounts for optical density dependence on the energy, was empirically determined. The effects of detector thickness in depth dose measurements and of the film orientation with respect to beam direction were investigated. The results show that the MD-55-2 films provide dose measurements with the films positioned perpendicularly to the proton beam. A dosimetric formalizm is proposed to determine the dose to water at depth d, with films oriented perpendicularly to the beam axis. This formalism uses a calibration factor of the radiochromic film determined directly on the proton beam at a reference depth in water, and the P(lin) factor, that takes into account the nonlinearity of the calibration curve and the P(en) factor that, in turn takes into account the change of proton beam energy in water. The MD-55-2 films with their high spatial resolution and the quasiwater equivalent material are attractive, positioned perpendicularly along the beam axis, for the absolute dose determination of very small beam sizes and modulated proton beams. 相似文献
15.
Vincenzo Di Stefano Raffaele Ornello Andrea Gagliardo Angelo Torrente Elisa Illuminato Valeria Caponnetto Ilaria Frattale Raffaella Golini Chiara Di Felice Fabiola Graziano Maria Caccamo Davide Ventimiglia Salvatore Iacono Gabriella Matarazzo Francesco Armetta Giuseppe Battaglia Alberto Firenze Simona Sacco Filippo Brighina 《Nutrients》2021,13(4)
Background: The restrictions taken to control the rapid spread of COVID-19 resulted in a sudden, unprecedented change in people’s lifestyle, leading to negative consequences on general health. This study aimed to estimate the impact of such changes on migraine severity during 2020 March–May lockdown. Methods: Patients affected by migraine with or without aura, diagnosed by expert physicians, completed a detailed interview comprehensive of: assessment of migraine characteristics; measure of physical activity (PA) levels; measure of the intake frequency of main Italian foods; the Insomnia Severity Index (ISI) questionnaire investigating sleep disorders. Results: We included 261 patients with a mean age of 44.5 ± 12.3 years. During social distancing, 72 patients (28%) reported a headache worsening, 86 (33%) an improvement, and 103 (39%) a stable headache frequency. A significant decrease of the PA levels during COVID-19 quarantine in the whole study sample was observed (median total metabolic equivalent task (METs) decreased from 1170 to 510; p < 0.001). Additionally, a significant difference was reported on median ISI scores (from 7 to 8; p < 0.001), which were increased in patients who presented a stable or worsening headache. Conclusions: Our study confirmed that the restrictions taken during the pandemic have affected the practice of PA levels and sleep quality in migraine. Hence, PA and sleep quality should be assessed to find strategies for an improvement in quality of life. 相似文献
16.
Maurizio Iaria Carlo Pellegrino Elena Cremaschi Enzo Capocasale Raffaele Dalla Valle Paolo Del Rio Carmelo Puliatti 《Transplantation proceedings》2021,53(3):1055-1057
BackgroundLymphatic disorders (LDs) are the most common minor complications after kidney transplantation (KT), with an incidence rate between 0.6% and 33.9%, which appears to be related to both surgical and medical factors. LDs mostly resolve spontaneously, but occasionally a surgical approach may be required.Materials and MethodsWe report our experience with 7 KT recipients who developed persistent lymphorrhea (>150 mL/24 h) between October 2017 and March 2019. All cases were treated as outpatients with parietal fistulectomy (PF). The fibrotic aponeurotic-cutaneous tract was thoroughly excised, and the residual aponeurotic defect was closed by watertight suturing. Serial abdominal ultrasounds (US) were carried out after the procedure.ResultsA small perirenal graft lymphocele of <2 cm was detected by US in all patients after 48 to 72 hours, without any evidence of either vascular or ureteral compression. During the subsequent scheduled US follow-up, lymphoceles did not increase in size, and additional interventions were not needed. Neither superficial nor deep surgical-site infections were recorded in such patients.ConclusionsPF was found to be a safe and effective minimally invasive approach for persistent lymphorrhea after KT. It could be easily performed with local anesthesia in a day surgery setting and did not require patient hospitalization. 相似文献
17.
Salvatore Cicciarello Guglielmo Borgia Jane Crowell Rocco Ciampi Raimondo Cerini Raffaele Orlando Michelina Mainolfi Laura Reynaud Michele Milano Marcello Piazza 《European journal of epidemiology》1997,13(1):49-54
HCV is ubiquitous. In 50% of all cases it causes chronic hepatitis that often evolves into liver cirrhosis and hepatocellular carcinoma. Recently HCV has been classified in 5 genotypes by Okamoto. The purpose of this study is to evaluate the prevalence of 5 genotypes in Campania, a region of Southern Italy, where the prevalence of anti-HCV antibodies ranges from 0.87 to 4%, and to evaluate the correlation between the HCV genotypes and the severity of histological damage. One hundred and thirty-five anti-HCV positive patients were enrolled and tested by PCR to identify HCV-RNA. One hundred and twenty-four patients resulted HCV-RNA positive. Genotyping was performed as described by Okamoto et al. with minor modifications of the specific primer to type III proposed by Silini et al. Eight patients were negative for all genotypes. Eight patients were positive for type I(1a), 61 for type II(1b), 39 for type III(2a), 11 for type IV(2b) and 1 for type V(3a). In 4 cases two different genotypes were present in the same sample [II(1b)-IV(2b), III(2a)-II(1b) twice, III(2a)-IV(2b)]. Histological evaluation of liver damage showed: CPH (22 cases), minimal CAH (56), severe CAH (31) and liver cirrhosis (15). There was no statistically significant correlation between the 5 genotypes and the severity of histological damage. Data on the prevalence of genotype II(1b) in Italy are similar to those reported for other European countries. The prevalence of genotypes in Southern Italy is similar to that reported in the population of Northern Italy. 相似文献
18.
De Caro R Raffaele De Caro Parenti A Montisci M Guidolin D Macchi V 《Stroke; a journal of cerebral circulation》2000,31(5):1187-1193
BACKGROUND AND PURPOSE: Symmetrical necrosis of the brain stem nuclei has been described as a consequence of severe transitory cerebral hypoxia mainly in neonates or young adults who experienced an episode of acute ischemia due to transitory acute heart failure. We report selective bilateral lesions of the solitary tract nuclei in 5 adults with short survival intervals after acute heart failure. METHODS: In 5 patients who died due to cardiovascular pathology, histological examination was performed on multiple samples of cerebral hemispheres, on transverse sections of the midbrain and pons, and on transverse serial sections of the medulla stained with hematoxylin-eosin, Klüver-Barrera, and Luxol fast blue. The 3-dimensional reconstruction of the extension and topography of the medullary lesions was obtained with computed image analysis. RESULTS: In 4 subjects who died soon after an episode of acute heart failure (range of survival 10 hours to 2 days), the dorsal portion of the solitary tract nuclei showed an eosinophilic roundish aspect bilaterally. In their context, the neurons showed changes characteristic of ischemic coagulation necrosis. In a fifth patient, a 32-year-old man who died 15 days after an episode of cardiac arrest, 2 circumscribed symmetrical infarcts with macrophagic and astrocytic reactions were found at the same level. The topography of the lesions and the inflammatory reaction and gliosis of patient 5 suggest that the findings in the other 4 patients correspond to initial features of selective lesions of the solitary tract nuclei after acute heart failure: the short interval of survival prevented the evolution of the reactive process. The nucleus is localized at the watershed zone between the terminal branches of the medullary collateral vessels of the vertebral arteries, thus representing the last meadow in the case of sudden fall of the systemic blood flow due to acute heart failure. The absence of lesions of other medullary and pontine nuclei accounts for a selective vulnerability of the neurons of the solitary tract nuclei, and the selective dendritic lesions suggest an excitotoxic component to ischemic cell death. CONCLUSIONS: The commonly accepted resistance of the medullary centers to ischemic hypoxia in adults apparently could be due to the rapidity of death, which prevents the evolution of lesions that can be diagnosed. In addition, minor lesions in the medullary tegmentum after acute heart failure could play a role in the prevention of the resumption of autonomous cardiac and respiratory functions despite life-saving procedures. 相似文献
19.
Soluble CD40 ligand plasma levels in lung cancer. 总被引:7,自引:0,他引:7
Mario Roselli Tommaso C Mineo Stefania Basili Francesca Martini Sabrina Mariotti Simona Aloe Girolamo Del Monte Vincenzo Ambrogi Antonella Spila Raffaele Palmirotta Roberta D'Alessandro Giovanni Davì Fiorella Guadagni Patrizia Ferroni 《Clinical cancer research》2004,10(2):610-614
PURPOSE: Tumor-induced platelet activation may cause the release of various cytokines, including CD40 ligand (CD40L). Activation of the CD40/CD40L pathway in human tumors may result in thrombin generation, which is known to be involved in angiogenesis. Thus, we investigated whether soluble (s)CD40L levels are increased in patients with lung cancer as a result of platelet and/or coagulation activation. EXPERIMENTAL DESIGN: Citrated plasma samples were obtained from 120 patients with different stages and histotypes of lung cancer and 60 age- and sex-matched control subjects. sCD40L, sP-selectin (marker of platelet activation), prothrombin fragment 1 + 2, and thrombin-antithrombin III complex levels (both markers of coagulative activation) were measured in all samples. RESULTS: Patients with lung cancer had median sCD40L levels higher than in control subjects (0.46 versus 0.13 ng/ml; P < 0.0001), although correlation with the stage of disease was not evident. Nonetheless, sCD40L levels were significantly higher in squamous cancer compared with adenocarcinoma (0.75 versus 0.27 ng/ml; P < 0.05). Moreover, median sCD40L levels were higher in stage IV compared with nonmetastatic squamous lung cancer (1.02 versus 0.61 ng/ml; P < 0.05). sCD40L levels significantly correlated with sP-selectin (P < 0.001), prothrombin fragment 1 + 2 (P < 0.001), or thrombin-antithrombin III complex (P < 0.05) in squamous lung cancer, but only sP-selectin (P = 0.011) was independently related to sCD40L. CONCLUSIONS: These findings indicate that elevated sCD40L levels can be preferentially found in patients with advanced squamous cancer and provide evidence that increased levels of this cytokine are associated to the occurrence of in vivo platelet activation. 相似文献
20.
Roberto Marchioli Guido Finazzi Raffaele Landolfi Jack Kutti Heinz Gisslinger Carlo Patrono Raphael Marilus Ana Villegas Gianni Tognoni Tiziano Barbui 《Journal of clinical oncology》2005,23(10):2224-2232
PURPOSE: The clinical course of polycythemia vera is often complicated by thrombosis as well as by the possible transition to myeloid metaplasia with myelofibrosis or acute myeloid leukemia. The aim of this study was to assess the rate of these complications in subjects receiving currently recommended treatments. PATIENTS AND METHODS: Overall, 1,638 patients from 12 countries were enrolled onto a large, prospective multicenter project aimed at describing the clinical history of polycythemia vera for the following outcomes: survival, the cumulative rate of cardiovascular death and thrombosis, the cumulative rate of leukemia, myelodysplasia, and myelofibrosis. The mean duration of the disease at entry and the duration of the follow-up were 4.9 and 2.7 years, respectively. RESULTS: The overall mortality rate of 3.7 deaths per 100 persons per year resulted from a moderate risk of cardiovascular death and a high risk of death from noncardiovascular causes (mainly hematologic transformations). Age older than 65 years and a positive history of thrombosis were the most important predictors of cardiovascular events. Antiplatelet therapy, but not cytoreductive treatment, was significantly associated with a lower risk of cardiovascular events. We found a consistent association between age and risk of leukemia, and between duration of the disease with risk of myelofibrosis. CONCLUSION: The European Collaboration on Low-Dose Aspirin in Polycythemia Vera study documents that large international collaborative studies are feasible in this field, in which few epidemiologic data are available. The persistently high mortality rate from hematologic malignancies characterizes the unmet therapeutic need of polycythemic patients and suggests a priority for future studies in this disease. 相似文献