全文获取类型
收费全文 | 128954篇 |
免费 | 5436篇 |
国内免费 | 297篇 |
专业分类
耳鼻咽喉 | 2014篇 |
儿科学 | 4018篇 |
妇产科学 | 2800篇 |
基础医学 | 17397篇 |
口腔科学 | 4371篇 |
临床医学 | 7857篇 |
内科学 | 32013篇 |
皮肤病学 | 4150篇 |
神经病学 | 10059篇 |
特种医学 | 2981篇 |
外国民族医学 | 1篇 |
外科学 | 15966篇 |
综合类 | 705篇 |
一般理论 | 37篇 |
预防医学 | 12539篇 |
眼科学 | 2861篇 |
药学 | 8779篇 |
中国医学 | 625篇 |
肿瘤学 | 5514篇 |
出版年
2023年 | 806篇 |
2022年 | 666篇 |
2021年 | 2749篇 |
2020年 | 1380篇 |
2019年 | 3022篇 |
2018年 | 4972篇 |
2017年 | 2894篇 |
2016年 | 2679篇 |
2015年 | 2991篇 |
2014年 | 3509篇 |
2013年 | 5257篇 |
2012年 | 9205篇 |
2011年 | 9826篇 |
2010年 | 4954篇 |
2009年 | 3529篇 |
2008年 | 7850篇 |
2007年 | 8386篇 |
2006年 | 7763篇 |
2005年 | 7696篇 |
2004年 | 6796篇 |
2003年 | 6395篇 |
2002年 | 6010篇 |
2001年 | 3852篇 |
2000年 | 4472篇 |
1999年 | 3342篇 |
1998年 | 562篇 |
1997年 | 357篇 |
1996年 | 354篇 |
1995年 | 274篇 |
1994年 | 216篇 |
1992年 | 1272篇 |
1991年 | 1065篇 |
1990年 | 939篇 |
1989年 | 779篇 |
1988年 | 648篇 |
1987年 | 636篇 |
1986年 | 632篇 |
1985年 | 532篇 |
1984年 | 398篇 |
1983年 | 300篇 |
1979年 | 332篇 |
1975年 | 270篇 |
1974年 | 315篇 |
1973年 | 349篇 |
1972年 | 288篇 |
1971年 | 315篇 |
1970年 | 290篇 |
1969年 | 292篇 |
1968年 | 269篇 |
1967年 | 236篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Joana Correia Fátima Franco Silva Carla Roque Henrique Vieira Luís Augusto Providéncia 《Revista portuguesa de cardiologia》2007,26(4):335-343
BACKGROUND: High rates of morbidity and mortality are observed in patients with advanced heart failure (AHF). AHF is now considered the most costly syndrome in cardiology owing to the substantial economic burden associated with hospitalizations for acute decompensation. A management program that involves specialized follow-up by a multidisciplinary team has been suggested as a desirable strategy for improving outcomes for these patients. ObjectivE: To evaluate the impact of a specialized outpatient heart failure (HF) follow-up program for patients with AHF on frequency and duration of hospitalization for HF and functional status. METHODS: We retrospectively studied 167 consecutive patients with AHF who were referred to the outpatient HF follow-up program in our institution between January and November 2002, of whom 147 followed for > or =30 days were included in the analysis. In addition to demographic and baseline clinical characteristics, HF medication and NYHA functional class, the number and duration of hospitalizations for HF during the previous 12 months were recorded and compared at the time of referral and after a follow-up period of 6.5+/-3 months. RESULTS: Of the 147 patients analyzed (aged 60.8+/-13 years; 79% male; left ventricular ejection fraction 27+/-11%), 67% were in NYHA functional class III, 20% in class II and 13% in class IV at the time of referral. There was a significant improvement in functional class during the mean follow-up period: 55% of the patients were in class III, 37% in class II, 5% in class I and 3% in class IV (p<0.0001). The proportion of patients on beta-blockers or spironolactone increased from 33% and 51% at the time of referral to 69% and 71% respectively after referral (p<0.0001). In the 12 months before referral, 39% of the patients had been hospitalized for acute decompensation of HF (87 hospitalizations - mean 7.2/month) versus 13% of the patients during the mean follow-up period (25 hospitalizations - 3.8/month, p<0.0001). No significant differences were found in the proportion of patients on angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, digoxin or diuretics, or in the mean duration of hospitalization before and after referral. ConclusioN: The specialized follow-up of patients with AHF by a team with expertise in HF resulted in significant therapeutic optimization. Increased use of beta-blockers and spironolactone was associated with significant improvement in functional capacity and significant reduction in hospitalizations. 相似文献
52.
Hybrid tumours of the salivary glands. A report of two cases involving the palate and a review of the literature 总被引:1,自引:0,他引:1
Luz María Ruíz-Godoy R Adalberto Mosqueda-Taylor Lourdes Suárez-Roa Adela Poitevin Esther Bandala-Sánchez Abelardo Meneses-García 《European archives of oto-rhino-laryngology》2003,260(6):312-315
Hybrid tumours are very rare salivary gland lesions composed of two or more different tumoural entities in a single neoplasm that arise within a definite topographical region. In most cases adenoid cystic carcinoma has been the predominant component in these lesions. In this study we describe two patients with hybrid tumours located in the palate, one in a 49-year-old woman and one in a 71-year-old man. The first case involved adenoid cystic carcinoma and mucoepidermoid carcinoma, and the patient in the second case exhibited adenoid cystic carcinoma and epithelial-myoepithelial carcinoma. Both patients were treated with surgery and radiotherapy, and there has been no evidence of recurrence after 13 and 36 months of follow-up, respectively. The recognition of the histologic component with the higher grade of malignancy in every case of hybrid tumour of the salivary glands is a necessary step to determine the biological behaviour and, consequently, to determine the proper therapeutic approach. 相似文献
53.
Aldo Cunha Medeiros Irami Araújo Filho Vítor Brasil Medeiros Laíza Araújo Mohana Pinheiro Flávio Henrique Miranda Araújo Freire Italo Medeiros Azevedo José Brand?o-Neto 《Journal of investigative surgery》2007,20(1):41-48
After total gastrectomy, the ileocecal graft may act as a reservoir and protect against reflux but give rise to transposition of the ileum and cause possible changes in bile acid metabolism and nutrition. This study compared the ileocecal graft and jejunal pouch. Male Wistar rats weighing 265 +/- 22 g were submitted to sham operation (S), ileocecal interposition graft (IIG), and jejunal pouch interposition graft (JP) after total gastrectomy. Eight weeks later, the esophagus was examined for evidence of esophagitis. Nutritional biochemistry and weight profile were documented preoperatively and 8 weeks after surgery. The oral glucose tolerance test was performed. Thirty-three rats were operated on and 30 survived for 8 weeks. Esophagitis occurred in seven JP rats. Body weight was significantly higher in IIG than in JP rats (p < .05). Normal glucose tolerance to intragastric glucose load was observed in sham and operated rats. JP rats had a significant decrease in serum albumin, glucose, transferrin, hemoglobin, iron, folate, and calcium, compared to sham (p < .05). Cobalamine was significantly lower in IIG rats than in JP rats (p < .05). In the IIG and JP groups, serum/hepatic total bile acid did not differ significantly from preoperative and sham values. In conclusion, the IIG interposition graft in rats prevented esophagitis, preserved nutrition, and did not interfere with enterohepatic total bile acid circulation. 相似文献
54.
Luís Mariano Isabel Vila?a Jorge Almeida Mota Garcia Maria Júlia Maciel 《Revista portuguesa de cardiologia》2007,26(3):265-270
Apical ballooning is a novel clinical entity reported in different contexts of physical and psychological stress, which is more common in middle-aged women. Of unknown etiology, the syndrome is characterized by a sudden and transient dilatation of the left ventricular apex in the absence of obstructive atherosclerotic coronary disease or evidence of myocardial necrosis, with total late recovery of ventricular function. The authors report the case of a 53-year-old woman who was admitted to the emergency room with left arm ischemia and low cardiac output, requiring ventilatory support. Left catheterization showed typical medial and apical myocardial dysfunction, with normal coronary arteries. Transesophageal echocardiography revealed a thrombus attached to the lower face of the aortic arch, which probably explained the thromboembolism of the arm but was unlikely to be the cause of the left ventricular dysfunction since there were no enzymatic or electrocardiographic signs of myocardial necrosis and normal wall motion was fully recovered. 相似文献
55.
56.
J Caballería 《Clinical therapeutics》1991,13(4):511-520
It has been demonstrated recently that some portion of ingested alcohol does not enter the systemic circulation and is not retained in the gastrointestinal tract; instead, gastric oxidation or first-pass metabolism of ethanol occurs in the stomach, catalyzed by gastric alcohol dehydrogenase. First-pass metabolism of ethanol is minimal in the fasting state; it is lower in women than in men, and in alcoholics than in nonalcoholics; and it is abolished in patients after subtotal gastrectomy. In addition, some drugs may affect first-pass ethanol metabolism. Studies of the effects of H2-receptor antagonists on blood ethanol levels are reviewed. It is concluded that some H2-receptor antagonists (cimetidine and nizatidine, in particular) can inhibit gastric ethanol oxidation and thus increase blood alcohol levels after drinking. The clinical and medicolegal implications of these findings are discussed. 相似文献
57.
AIM: The aim of this study was to quantify the flow-mediated dilatation (FMD) of brachial artery in asymptomatic members of families with familial combined hyperlipidemia (FCH) and to determine the relation between FMD and risk factors accompanying FCH. We also investigated the association between FMD and the intima-media thickness (IMT) of the common carotid artery. METHODS: Eighty-two members of 29 FCH families were divided into two groups: probands and hyperlipidemic first-degree relatives (HL) (n=47) and normolipidemic first-degree relatives (NL) (n=35). The control (C) groups, C-HL (n=20) and C-NL (n=20), consisted of sex- and age-matched healthy individuals. FMD was assessed in the brachial artery by measuring the change in brachial artery diameter in response to reactive hyperemia. RESULTS: Both hyperlipidemic subjects and their NL had significantly lower FMD (3.4+/-3% vs 6.3+/-2.8%, P<0.001, 5.2+/-2.3% vs 7.8+/-2.8%, P<0.01, respectively) compared to controls. In multivariate backward stepwise regression analysis, FMD in members of FCH families was independently associated with sex (P<0.001), age (P<0.01), C-peptide (P<0.05) and borderline with glycemia (P=0.052). FMD correlated inversely with IMT in all subjects of FCH families and in hyperlipidemic members. In multivariate backward stepwise regression analysis this relation remained independent (P<0.001, P<0.01, respectively). CONCLUSIONS: Members of FCH families showed impaired FMD, which was independently associated with markers of insulin resistance. FMD and IMT were independently associated in hyperlipidemic, but not in normolipidemic members of FCH families. 相似文献
58.
Jo?o Maldonado Telmo Pereira Jorge Polónia Luís Martins 《Revista portuguesa de cardiologia》2006,25(7-8):709-714
BACKGROUND: Aerobic exercise training has been associated with beneficial effects on the cardiovascular system, improving arterial compliance, possibly related to a positive impact on the endothelium. The effects of competitive aerobic exercise are not so well documented. This prompted us to evaluate the possible modulation of arterial properties in a group of athletes and their response to the aging process. METHODS: 423 healthy males were enrolled in a cross-sectional study, 212 of whom were competitive athletes and 211 were controls. All underwent carotid-femoral pulse wave velocity (PWV) evaluation, and casual blood pressure and other relevant anthropometric data were evaluated. RESULTS: To control the effects of age, each group was divided into two subgroups with an age cut-point of 20 years. PWV was 6.3 +/- 0.9 m/s (athletes) vs. 7.0 +/- 1.0 m/s (controls) for ages <20 years, and 7.6 +/- 1.2 m/s (athletes) vs. 8.1 +/- 0.9 m/s (controls) for ages >20 years, with statistically significant differences in both comparisons. A linear regression model with logarithmic tendency analysis with age as the independent determinant of PWV revealed a different progression of age-related deterioration of aortic compliance between the two groups (athletes and controls). CONCLUSIONS: Our data documented better compliance indices in competition athletes compared with controls, which may reflect optimization of endothelial function. This improvement was age-dependent, being less pronounced as the athletes grow older, which could be due partially to sustained stretching effects on the arterial walls in long-term competitors. 相似文献
59.
Jorge Polónia Jo?o Maldonado Rui Ramos Susana Bertoquini Mary Duro Cristina Almeida Jo?o Ferreira Loide Barbosa José Alberto Silva Luís Martins 《Revista portuguesa de cardiologia》2006,25(9):801-817
BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events. 相似文献
60.
The cognit: a network model of cortical representation. 总被引:4,自引:0,他引:4
Joaquín M Fuster 《International journal of psychophysiology》2006,60(2):125-132
The prevalent concept in modular models is that there are discrete cortical domains dedicated more or less exclusively to such cognitive functions as visual discrimination, language, spatial attention, face recognition, motor programming, memory retrieval, and working memory. Most of these models have failed or languished for lack of conclusive evidence. In their stead, network models are emerging as more suitable and productive alternatives. Network models are predicated on the basic tenet that cognitive representations consist of widely distributed networks of cortical neurons. Cognitive functions, namely perception, attention, memory, language, and intelligence, consist of neural transactions within and between these networks. The present model postulates that memory and knowledge are represented by distributed, interactive, and overlapping networks of neurons in association cortex. Such networks, named cognits, constitute the basic units of memory or knowledge. The association cortex of posterior-post-rolandic-regions contains perceptual cognits: cognitive networks made of neurons associated by information acquired through the senses. Conversely, frontal association cortex contains executive cognits, made of neurons associated by information related to action. In both posterior and frontal cortex, cognits are hierarchically organized. At the bottom of that organization-that is, in parasensory and premotor cortex-cognits are small and relatively simple, representing simple percepts or motor acts. At the top of the organization-in temporo-parietal and prefrontal cortex-cognits are wider and represent complex and abstract information of perceptual or executive character. Posterior and frontal networks are associated by long reciprocal cortico-cortical connections. These connections support the dynamics of the perception-action cycle in sequential behavior, speech, and reasoning. 相似文献