全文获取类型
收费全文 | 859627篇 |
免费 | 49403篇 |
国内免费 | 1703篇 |
专业分类
耳鼻咽喉 | 11694篇 |
儿科学 | 27526篇 |
妇产科学 | 20982篇 |
基础医学 | 130137篇 |
口腔科学 | 25354篇 |
临床医学 | 73205篇 |
内科学 | 170317篇 |
皮肤病学 | 20928篇 |
神经病学 | 61489篇 |
特种医学 | 29053篇 |
外国民族医学 | 78篇 |
外科学 | 122288篇 |
综合类 | 15767篇 |
现状与发展 | 2篇 |
一般理论 | 202篇 |
预防医学 | 65893篇 |
眼科学 | 19582篇 |
药学 | 64294篇 |
21篇 | |
中国医学 | 3185篇 |
肿瘤学 | 48736篇 |
出版年
2021年 | 9564篇 |
2019年 | 9385篇 |
2018年 | 13198篇 |
2017年 | 9296篇 |
2016年 | 9861篇 |
2015年 | 10933篇 |
2014年 | 14817篇 |
2013年 | 21943篇 |
2012年 | 30752篇 |
2011年 | 32557篇 |
2010年 | 18547篇 |
2009年 | 16432篇 |
2008年 | 28503篇 |
2007年 | 30489篇 |
2006年 | 30224篇 |
2005年 | 28735篇 |
2004年 | 27393篇 |
2003年 | 25801篇 |
2002年 | 24814篇 |
2001年 | 40308篇 |
2000年 | 41443篇 |
1999年 | 33939篇 |
1998年 | 8666篇 |
1997年 | 7260篇 |
1996年 | 7463篇 |
1995年 | 7052篇 |
1994年 | 6439篇 |
1992年 | 24358篇 |
1991年 | 24094篇 |
1990年 | 23353篇 |
1989年 | 22937篇 |
1988年 | 20790篇 |
1987年 | 20103篇 |
1986年 | 19176篇 |
1985年 | 17903篇 |
1984年 | 13127篇 |
1983年 | 11105篇 |
1982年 | 6142篇 |
1979年 | 11921篇 |
1978年 | 8401篇 |
1977年 | 7046篇 |
1976年 | 6815篇 |
1975年 | 7550篇 |
1974年 | 8855篇 |
1973年 | 8507篇 |
1972年 | 7972篇 |
1971年 | 7462篇 |
1970年 | 7187篇 |
1969年 | 6635篇 |
1968年 | 6073篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
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
992.
993.
994.
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
995.
Hasan F Batirel Saime Batirel Richard N Mitchell Scott J Swanson 《The Journal of heart and lung transplantation》2005,24(6):658-664
BACKGROUND: Interferon-gamma, produced by T-helper cells, activates macrophages and increases expression of major histocompatibility complex (MHC) products in acute and chronic rejection. We investigated the role of interferon-gamma in murine heterotopic tracheal allografts. METHODS: Tracheas from BALB/c mice were heterotopically transplanted to BALB/c (12 isografts: 2 weeks [n = 6] and 4 weeks [n = 6], C57BL/6 (12 allografts: 2 weeks [n = 6] and 4 weeks [n = 6]) and C57BL/6 interferon-gamma knockout mice (12 interferon-gamma knockout allografts: 2 weeks [n = 4] and 4 weeks [n = 8]). BALB/c interferon-gamma knockout tracheas were transplanted to C57BL/6 mice (reverse knockout: 4 weeks [n = 6]) and BALB/c interferon-gamma knockout mice (4 weeks [n = 2]). C57BL/6 tracheas were transplanted to Bm12 mice (MHC Class II mismatch allografts: 4 weeks [n = 6]). Conventional histology and immunohistochemistry for CD4, CD8 and CD11b were performed. RESULTS: Minimal (<20%) obliteration was seen at 2 weeks in the allograft groups. No obliteration was seen in the isograft groups. However, all allografts were completely obliterated at 4 weeks. Interferon-gamma knockout allograft combinations displayed severe rejection characterized by intense intra- and extraluminal infiltration by CD4-, CD8- and CD11b-labeled cells. The MHC Class II mismatch allograft group showed normal epithelium and mild sub-epithelial infiltration by CD4+ cells at 4 weeks (CD8-, CD11b-). CONCLUSIONS: Absence of interferon-gamma does not protect the allograft from obliteration. Epithelial destruction by cytotoxic T cells appears to be an important mechanism in the development of obliteration in murine heterotopic tracheal allografts. 相似文献
996.
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
997.
998.
999.
Michelle K Nurzenski N Kathryn Briffa Roger I Price Benjamin C C Khoo Amanda Devine Thomas J Beck Richard L Prince 《Journal of bone and mineral research》2007,22(3):416-424
A population-based study on 1008 postmenopausal women identified that the 24% of women achieving high levels of PA and CI had 3.4-4.4% higher femoral bone strength in axial compression and 1.7-5.2% in bending than those achieving low levels, indicating that lifestyle factors influence bone strength in the proximal femur. INTRODUCTION: Extensive research has shown that increased physical activity (PA) and calcium intake (CI) decrease the rate of bone loss; however, there is little research on how these lifestyle variables affect bone geometry. This study was designed to investigate the effects of modifiable lifestyle variables, habitual PA and dietary CI, on femoral geometry in older women. MATERIALS AND METHODS: Femoral geometry, habitual PA, and dietary CI were measured in a population-based sample of 1008 women (median age+/-interquartile range, 75+/-4years) enrolled in a randomized controlled trial (RCT) of calcium supplementation. Baseline PA and CI were assessed by validated questionnaires, and 1-year DXA scans (Hologic 4500A) were analyzed using the hip structural analysis technique. Section modulus (Z), an index of bending strength, cross-sectional area (CSA), an index of axial compression strength, subperiosteal width (SPW), and centroid position, the position of the center of mass, were measured at the femoral neck (NN), intertrochanter (IT), and femoral shaft (FS) sites. These data were divided into tertiles of PA and CI, and the results were compared using analysis of covariance (ANCOVA), with corrections for age, height, weight, and treatment (calcium/placebo). RESULTS AND CONCLUSIONS: PA showed a significant dose-response effect on CSA all hip sites (p<0.03) and Z at the narrow neck and intertrochanter sites (p<0.02). For CI, there was a dose-response effect for centroid position at the intertrochanter (p=0.03). These effects were additive, such that the women (n=240) with PA in excess of 65.5 kcal/day and CI in excess of 1039 mg/day had significantly greater CSA (NN, 4.4%; IT, 4.3%; FS, 3.4%) and Z (NN, 3.9%; IT, 5.2%). These data show a favorable association between PA and aspects of bone structural geometry consistent with better bone strength. Association between CI and bone structure was only evident in 1 of 15 variables tested. However, there was evidence that there may be additive effects, whereby women with high levels of PA and CI in excess of 1039 mg/day had significantly greater CSA (NN, 0.4%; FS, 2.1%) and Z (IT, 3.0%) than women with high PA but low CI. These data show that current public health guidelines for PA and dietary CI are not inappropriate where bone structure is the health component of interest. 相似文献
1000.
Persistent hip stiffness in Perthes’ disease indicates a poor prognosis and is a therapeutic challenge. We report a case of a 13-year-old boy with a stiff Perthes’ hip that was nonresponsive to prolonged nonsurgical treatment. Imaging revealed Catterall group IV Perthes’ disease in an advanced reossification stage, with a focal defect in the weight-bearing area of the capital femoral epiphysis. A focal, compressible chondral elevation was detected on hip arthroscopy; on incision, flocculent fluid was released. After the cyst was excised, microfracture revascularization of the chondral defect was undertaken. Postoperatively, the patient had immediate pain relief, correction of deformity, and restoration of painless range of motion; this has continued for 4 years since surgery was performed. Persistence of an unhealed necrotic segment in Perthes’ disease has traditionally been associated with osteochondritis dissecans; however, in this case, the unhealed and nonossified segment produced an elevated painful chondral cyst that caused spasm and stiffness of the hip. Although 2 distinct types of chondral lesions have been described in Perthes’ disease, stiffness arising because of these lesions has not been reported. Patients with this unusual third type of chondral lesion of the capital femoral epiphysis, which causes persistent stiffness in Perthes’ hip, may be identified and successfully treated with the use of arthroscopic techniques. 相似文献