全文获取类型
收费全文 | 1363篇 |
免费 | 45篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 57篇 |
妇产科学 | 47篇 |
基础医学 | 180篇 |
口腔科学 | 46篇 |
临床医学 | 93篇 |
内科学 | 217篇 |
皮肤病学 | 12篇 |
神经病学 | 164篇 |
特种医学 | 48篇 |
外科学 | 184篇 |
综合类 | 7篇 |
预防医学 | 89篇 |
眼科学 | 31篇 |
药学 | 123篇 |
肿瘤学 | 87篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 26篇 |
2018年 | 17篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 69篇 |
2012年 | 74篇 |
2011年 | 83篇 |
2010年 | 50篇 |
2009年 | 41篇 |
2008年 | 82篇 |
2007年 | 86篇 |
2006年 | 100篇 |
2005年 | 95篇 |
2004年 | 112篇 |
2003年 | 91篇 |
2002年 | 104篇 |
2001年 | 24篇 |
2000年 | 10篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 11篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1963年 | 3篇 |
排序方式: 共有1411条查询结果,搜索用时 0 毫秒
71.
Manifestations of chronic disease during pregnancy 总被引:4,自引:0,他引:4
Context Physiologic changes of pregnancy include insulin resistance, thrombophilia, immunosuppression, and hypervolemia. These changes may herald the development of disease in later life. Objective To summarize current evidence on how pregnancy reveals risk of chronic disease. Evidence Acquisition MEDLINE was searched for articles published between 1990 and 2005 relating pregnancy conditions to the development of chronic disease. Bibliographies and the Web sites of the International Society of Obstetric Medicine and International Society for the Study of Hypertension in Pregnancy were also reviewed. Evidence Synthesis Pregnancy exaggerates atherogeniclike responses, including insulin resistance and dyslipidemia, manifesting as preeclampsia or gestational diabetes. These complications herald an increased risk of postpartum cardiovascular disease, with a 2-fold increased risk of coronary artery disease and stroke. Women with gestational diabetes mellitus can progress to type 2 diabetes mellitus. The rate of progression varies from 6% to 92% depending on diagnostic criteria, race/ethnicity, and duration of surveillance (from 6 months to 28 years). Pregnancy increases risk of venous thrombosis by 7- to 10-fold. Heritable thrombophilia is present in at least 15% of Western populations and underlies at least 50% of gestational venous thromboses. Thus, the procoagulant changes during pregnancy can unmask hereditary thrombophilia. An important adaptation leading to immunotolerance of the fetoplacental unit is a switch from helper T-cell (TH) 1 dominance to TH2 dominance. Patients with a TH1-dominant immune disease, such as rheumatoid arthritis or multiple sclerosis, improve during pregnancy. However, rheumatoid arthritis is 5 times more likely to develop after delivery than at any other time. During pregnancy, there is a 50% increase in plasma volume, which can unmask glomerulopathies, peripartum cardiomyopathy, arterial aneurysms, or arteriovenous malformations. Development of intrahepatic cholestasis of pregnancy predicts increased risk of later cholelithiasis. Conclusions The physiologic changes of pregnancy can reveal risk of chronic diseases. Exaggerated responses reflective of the metabolic syndrome are seen in preeclampsia and gestational diabetes and can herald future cardiovascular and metabolic disease. Pregnancy is therefore an important screening opportunity for cardiovascular and metabolic disease risk factors, with the possibility of early intervention. 相似文献
72.
73.
Hanna?TervonenEmail author Leif?B?ck Anja?Juvas Pirjo?R?s?nen Antti?A.?M?kitie Harri?Sintonen Risto?P.?Roine Erkki?Vilkman Leena-Maija?Aaltonen 《European archives of oto-rhino-laryngology》2005,262(10):816-820
For speech rehabilitation after total laryngectomy, the Provox FreeHands Heat and Moisture Exchanger (FreeHands HME; Atos Medical AB, Hörby, Sweden) was compared with the Provox Heat and Moisture Exchanger (HME), and the patients Health-Related Quality of Life (HRQoL) was assessed. A review of the English literature was performed considering automatic speaking valves. The study design was a cohort study. Fourteen laryngectomized male patients who had used the HME successfully before receiving the FreeHands HME entered the study. An ENT specialist and a speech pathologist examined these patients. Data concerning voicing, breathing, skin adhesion, voice and speech quality, and HRQoL were collected by a structured questionnaire. Voice recordings were performed for evaluation of the quality of the voice. A computer-aided search of the MED-LINE database was conducted, supplemented by hand searches of key journals. Twelve patients had used the FreeHands HME on special social occasions and reported three main reasons why FreeHands HME was unsuitable for continuous use: heavier breathing, more difficult speaking, and worse subjective quality of voice. With HME, phonation time tended to be longer and the softest phonation softer ( P =0.034). The loudest phonation was louder with FreeHands HME ( P =0.015). Patients HRQoL assessed by the 15D profile was similar to that of the age- and sex-matched male Finnish general population (patients 0.877, population 0.884). A review of the literature showed few works dealing with automatic speaking valves. The FreeHands HME is a useful additional device in a selected group of laryngectomized patients. Total laryngectomy did not lower patients HRQoL notably.Some of these data were presented at the 16th Annual Meeting of the Scandinavian Society for Head and Neck Oncology, 24 April 2004, in Oulu, Finland. 相似文献
74.
Bister V Salmela MT Heikkilä P Anttila A Rintala R Isaka K Andersson S Saarialho-Kere U 《Journal of pediatric gastroenterology and nutrition》2005,40(1):60-66
OBJECTIVES: Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of premature infants characterized histologically by extensive tissue injury and inflammation. Matrix metalloproteinases (MMP) are involved in tissue remodeling and cell migration, both being important aspects of inflammatory disease. The aim of this study was to investigate whether MMPs play a role in the pathogenesis of NEC. METHODS: Expression of MMP-1, -7, -9, -10, -12, -19 and -26 was studied using in situ hybridization/immunohistochemistry in samples intestinal tissue removed from 15 patients with NEC; in 7 of them control samples were obtained at closure of stomas. Six intestinal samples from patients with intestinal atresia and four samples of necrosis were also included in the material examined. Laminin-5 was immunostained to find migrating enterocytes and cytokeratin to delineate mucosal epithelium. RESULTS: MMP-7 protein was upregulated in the epithelium of 12/18 NEC samples. MMP-26 was induced in stromal cells of 12/17 NEC specimens. Stromal expression was found for MMP-1 and -12 mRNAs in 7/18 samples. MMP-1 was also detected in the epithelium of regenerating areas. Both NEC and stoma samples expressed MMP-9 in inflammatory cells. Epithelial MMP-19 was downregulated in NEC. CONCLUSIONS: Our results suggest that several MMPs may be major factors in tissue destruction and remodeling in NEC. Targeted inhibition of matrilysins, using synthetic MMP inhibitors or blockers of their signal transduction pathways, may represent a novel therapeutic option for the treatment of intestinal inflammation associated with NEC. 相似文献
75.
The present study aimed to find out how different stages of cortical auditory processing (sound encoding, discrimination, and orienting) are affected in children with autism. To this end, auditory event-related potentials (ERP) were studied in 15 children with autism and their controls. Their responses were recorded for pitch, duration, and vowel changes in speech stimuli, and for corresponding changes in the non-speech counterparts of the stimuli, while the children watched silent videos and ignored the stimuli. The responses to sound repetition were diminished in amplitude in the children with autism, reflecting impaired sound encoding. The mismatch negativity (MMN), an ERP indexing sound discrimination, was enhanced in the children with autism as far as pitch changes were concerned. This is consistent with earlier studies reporting auditory hypersensitivity and good pitch-processing abilities, as well as with theories proposing enhanced perception of local stimulus features in individuals with autism. The discrimination of duration changes was impaired in these children, however. Finally, involuntary orienting to sound changes, as reflected by the P3a ERP, was more impaired for speech than non-speech sounds in the children with autism, suggesting deficits particularly in social orienting. This has been proposed to be one of the earliest symptoms to emerge, with pervasive effects on later development. 相似文献
76.
Brain signatures of meaning access in action word recognition 总被引:3,自引:0,他引:3
The brain basis of action words may be neuron ensembles binding language- and action-related information that are dispersed over both language- and action-related cortical areas. This predicts fast spreading of neuronal activity from language areas to specific sensorimotor areas when action words semantically related to different parts of the body are being perceived. To test this, fast neurophysiological imaging was applied to reveal spatiotemporal activity patterns elicited by words with different action-related meaning. Spoken words referring to actions involving the face or leg were presented while subjects engaged in a distraction task and their brain activity was recorded using high-density magnetoencephalography. Shortly after the words could be recognized as unique lexical items, objective source localization using minimum norm current estimates revealed activation in superior temporal (130 msec) and inferior frontocentral areas (142-146 msec). Face-word stimuli activated inferior frontocentral areas more strongly than leg words, whereas the reverse was found at superior central sites (170 msec), thus reflecting the cortical somatotopy of motor actions signified by the words. Significant correlations were found between local source strengths in the frontocentral cortex calculated for all participants and their semantic ratings of the stimulus words, thus further establishing a close relationship between word meaning access and neurophysiology. These results show that meaning access in action word recognition is an early automatic process ref lected by spatiotemporal signatures of word-evoked activity. Word-related distributed neuronal assemblies with specific cortical topographies can explain the observed spatiotemporal dynamics reflecting word meaning access. 相似文献
77.
Plasma 8-isoprostane is increased in preterm infants who develop bronchopulmonary dysplasia or periventricular leukomalacia 总被引:2,自引:0,他引:2
Our aim was to assess the plasma free 8-epi-prostaglandin F(2alpha) (8-isoprostane) and ascorbyl radical as risk indicators for oxidative damage in extremely low birth weight infants (ELBWIs) and the effect of N-acetylcysteine (NAC) on these markers. Plasma samples were collected on days 3 and 7 of life from infants who were enrolled in a randomized, controlled trial in which i.v. NAC or placebo was administered to ELBWIs during the first week of life, with the aim of preventing bronchopulmonary dysplasia (BPD). Plasma 8-isoprostane was analyzed in 83 infants using an enzyme immunoassay kit. Ascorbyl radical concentration was measured in 61 infants with electron spin resonance spectroscopy. The 8-isoprostane concentrations were similar in the NAC and placebo groups. In infants who later developed BPD or died (n = 29), the median (range) 8-isoprostane concentration was significantly higher (p = 0.001) on day 3 and day 7 [50.0 pg/mL (19-360) and 57.0 pg/mL (14-460), respectively] than in survivors without BPD [n = 54; 34.5 pg/mL (5-240) and 39.5 pg/mL (7-400), respectively]. The 8-isoprostane levels increased significantly more (p < 0.05) in infants who later developed periventricular leukomalacia. NAC treatment or the later development of BPD was not related to the ascorbyl radical levels. The ascorbyl radical level decreased significantly in all groups from day 3 to day 7, but the difference between the groups was not significant. The mean (SD) ascorbyl radical level on day 3 was significantly higher (p < 0.01) in infants who later developed periventricular leukomalacia [287 (124) versus 194 (90)]. These data suggest that plasma 8-isoprostane could serve as a marker in assessing the risk for BPD development in ELBWIs. 相似文献
78.
Pöyhiä R Hynynen M Seppälä T Roine RO Verkkala K Olkkola KT 《Journal of cardiothoracic and vascular anesthesia》2004,18(6):189-754
OBJECTIVE: In small to moderate doses, oxycodone has similar analgesic efficacy to morphine with fewer side effects. The present study evaluated the pharmacokinetics and dynamics of high doses of oxycodone during anesthesia for primary coronary artery bypass grafting. DESIGN: A randomized, prospective clinical evaluation. SETTING: A major Scandinavian university clinic. PARTICIPANTS: Two groups with 10 patients each were studied. INTERVENTIONS: Invasive hemodynamics, echocardiograms, and electrocardiograms were monitored. Oxycodone kinetics, histamine liberation, and plasma cortisol levels were measured. Anesthesia was induced with 1.0 mg/kg of oxycodone and, thereafter, in a random order, maintained with a continuous infusion of oxycodone at a rate of either 0.5 mg/kg/h (group OX 0.5, 10 patients) or 1.0 mg/kg/h (group OX 1.0, 10 patients). An additional bolus dose of 0.5 mg/kg (OX 0.5) or 1.0 mg/kg (OX 1.0) of oxycodone was given before the incision. Enflurane was administered according to hemodynamic criteria. MEASUREMENTS AND MAIN RESULTS: The induction of and the course of anesthesia were hemodynamically stable in all patients. Enflurane was given to every patient. The mean total doses of oxycodone were 3.5 mg/kg (OX 0.5) and 6.2 mg/kg (OX 1.0). The median t(1/2) of oxycodone varied from 5.1 to 5.9 hours. No hemodynamic differences were found between the groups. No histamine liberation was detected. During anesthesia, the predominant waves in the EEG were theta;- and delta-waves. The mean times to awakening were 3.8 hours and 7.0 hours in the groups OX 0.5 and 1.0, respectively. All patients were intubated until the first postoperative morning. No recall of awareness was reported. CONCLUSION: A combination of oxycodone and enflurane provides hemodynamically stable anesthesia. No advantages were gained with the higher dose. Elimination of oxycodone was slower than reported previously. 相似文献
79.
Lahtinen J Biancari F Ala-Kokko T Rainio P Salmela E Pokela R Satta J Lepojärvi M Juvonen T 《Scandinavian cardiovascular journal : SCJ》2004,38(2):104-112
OBJECTIVE: To evaluate whether pulmonary artery blood (PA) temperature on admission to the intensive care unit (ICU) is predictive of postoperative outcome after isolated on-pump coronary artery bypass grafting (CABG). DESIGN: A retrospective study on 1639 patients who underwent isolated on-pump CABG in whom PA temperature at admission to the ICU was available for review. RESULTS: Thirty-three patients (2.0%) died during the in-hospital stay and 87 patients (5.3%) developed low cardiac output syndrome. PA temperature at admission to the ICU was significantly associated with an increased risk of overall postoperative death (p = 0.002), cardiac death (p = 0.03), and low cardiac output syndrome (p < 0.0001), and was significantly correlated with prolonged length of ICU stay (p < 0.0001) and postoperative bleeding (p = 0.001). Patients with high PA temperature had significantly more severe comorbidities, and longer aortic cross-clamping and cardiopulmonary bypass time. The receiver operating characteristic curve showed that PA temperature at admission to the ICU in predicting postoperative death had an area under the curve of 0.660 (p = 0.002) and its best cut-off value was 36.4 degrees C (sensitivity: 63.6%, specificity: 65.2%). When the PA temperature at admission to the ICU was > or = 36.4 degrees C, the postoperative mortality and low cardiac output syndrome rates were 3.6 and 8.3%, whereas they were 1.1 and 3.7% when the PA temperature at admission to the ICU was < 36.4 degrees C (p = 0.001, p < 0.0001), respectively. CONCLUSION: Patients having a PA temperature > or =36.4 degrees C at admission to the ICU after CABG seem to be at higher risk of poor postoperative outcome. 相似文献
80.
Automatic time perception in the human brain for intervals ranging from milliseconds to seconds 总被引:6,自引:0,他引:6
Time perception in everyday life deals with various intervals. Here we investigated whether an automatic duration-discrimination mechanism in audition operates even for intervals of an order of seconds, by using the mismatch negativity (MMN), an index of automatic change detection in audition. In Experiment 1, occasional decrements of the duration of a repetitive "standard" tone elicited an MMN in subjects ignoring auditory stimulation, even with the standard-stimulus durations over a second. Nevertheless, the MMN amplitude was significantly diminished with standard-stimulus durations of 800 ms and above, despite the fact that a constant deviant versus standard duration ratio was used. Complementary experiments varying the interstimulus interval (Experiment 2) and the magnitude of duration change (Experiment 3) yielded corroborating results. The present results suggest that automatic duration discrimination in audition operates even for durations of the order of seconds; yet its optimum time scale might be of the order of milliseconds. 相似文献