全文获取类型
收费全文 | 169298篇 |
免费 | 10196篇 |
国内免费 | 416篇 |
专业分类
耳鼻咽喉 | 2221篇 |
儿科学 | 5501篇 |
妇产科学 | 3558篇 |
基础医学 | 23014篇 |
口腔科学 | 7486篇 |
临床医学 | 12382篇 |
内科学 | 37989篇 |
皮肤病学 | 4327篇 |
神经病学 | 14136篇 |
特种医学 | 5257篇 |
外国民族医学 | 26篇 |
外科学 | 20978篇 |
综合类 | 1385篇 |
现状与发展 | 1篇 |
一般理论 | 60篇 |
预防医学 | 17699篇 |
眼科学 | 3149篇 |
药学 | 10321篇 |
中国医学 | 688篇 |
肿瘤学 | 9732篇 |
出版年
2023年 | 819篇 |
2022年 | 1613篇 |
2021年 | 3613篇 |
2020年 | 2424篇 |
2019年 | 3415篇 |
2018年 | 4816篇 |
2017年 | 3610篇 |
2016年 | 3351篇 |
2015年 | 3929篇 |
2014年 | 5397篇 |
2013年 | 6815篇 |
2012年 | 10622篇 |
2011年 | 11109篇 |
2010年 | 5599篇 |
2009年 | 5037篇 |
2008年 | 8581篇 |
2007年 | 9196篇 |
2006年 | 8526篇 |
2005年 | 8819篇 |
2004年 | 8298篇 |
2003年 | 7582篇 |
2002年 | 5636篇 |
2001年 | 4940篇 |
2000年 | 4934篇 |
1999年 | 4337篇 |
1998年 | 1535篇 |
1997年 | 1280篇 |
1996年 | 1267篇 |
1995年 | 1074篇 |
1994年 | 1068篇 |
1993年 | 973篇 |
1992年 | 2646篇 |
1991年 | 2559篇 |
1990年 | 2332篇 |
1989年 | 2330篇 |
1988年 | 2101篇 |
1987年 | 1950篇 |
1986年 | 1824篇 |
1985年 | 1748篇 |
1984年 | 1253篇 |
1983年 | 1007篇 |
1982年 | 569篇 |
1981年 | 513篇 |
1980年 | 492篇 |
1979年 | 919篇 |
1978年 | 604篇 |
1977年 | 474篇 |
1975年 | 542篇 |
1974年 | 539篇 |
1973年 | 540篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Denis Mariano-Goulart Laurent Déchaux Fran?ois Rouzet Eric Barbotte Charles Caderas de Kerleau Michel Rossi Dominique Le Guludec 《Journal of nuclear medicine》2007,48(9):1416-1423
This study aimed to assess the ability of global and local systolic parameters measured with gated blood-pool SPECT (GBPS) to diagnose and characterize the severity of diffuse or localized arrhythmogenic right ventricular dysplasia (ARVD). METHODS: Fifty-nine subjects with symptomatic ventricular arrhythmias were prospectively included in the study. With the International Society and Federation of Cardiology criteria for ARVD as a gold standard, these subjects were classified as subjects without ARVD (21 control subjects) and patients with localized ARVD (16 patients) or diffuse ARVD (22 patients). Right ventricular volumes, right ventricular ejection fractions (EF), the SD of local EF (sigma-EF), and the SD of the local times of end systole (sigma-TES) were computed from GBPS data and compared among the groups in the study population. RESULTS: sigma-EF did not differ between control subjects and patients with diffuse or localized ARVD. Right ventricular EF and volumes differed between patients with diffuse ARVD and control subjects, with similar areas under the receiver-operating-characteristic curves, but right ventricular EF and volumes failed to differentiate patients with localized ARVD. In contrast, sigma-TES differed between patients with diffuse or localized ARVD and control subjects. Regression analysis showed that the systolic parameter most strongly associated with the diagnosis of ARVD was sigma-TES. The probabilities of a randomly chosen patient in the diffuse ARVD group and of a randomly chosen patient in the localized ARVD group having sigma-TES values greater than that of a randomly chosen control subject were 98.5% and 96.7%, respectively. For the diagnosis of localized ARVD, a threshold of 80 ms for sigma-TES corresponded to sensitivity, specificity, and positive and negative predictive values of 100%, 81%, 80%, and 100%, respectively. CONCLUSION: With GBPS, both diffuse ARVD and localized ARVD can be accurately diagnosed by computing sigma-TES for all of the pixels on the surface of the right ventricle. 相似文献
192.
Juli Busquets Jose Castellote Jaume Torras Juan Fabregat Emilio Ramos Laura Llado Antonio Rafecas Esmeralda de la Banda Juan Figueras 《Journal of gastrointestinal surgery》2007,11(4):458-463
Background Cold ischemia time and the presence of postoperative hepatic arterial thrombosis have been associated with biliary complications
(BC) after liver transplantation. An ABO-incompatible blood group has also been suggested as a factor for predisposal towards
BC. However, the influence of Rh nonidentity has not been studied previously.
Materials Three hundred fifty six liver transplants were performed from 1995 to 2000 at our hospital. BC incidence and risk factors
were studied in 345 patients.
Results Seventy patients (20%) presented BC after liver transplantation. Bile leakage (24/45%) and stenotic anastomosis (21/30%) were
the most frequent complications. Presence of BC in Rh-nonidentical graft–host cases (23/76, 30%) was higher than in Rh-identical
grafts (47/269, 17%) (P = 0.01). BC was also more frequent in grafts with arterial thrombosis (9/25, 36% vs 60/319, 19%; P = 0.03) and grafts with cold ischemia time longer than 430 min (26/174, 15% vs 44/171, 26%; P = 0.01). Multivariate logistic regression confirmed that Rh graft–host nonidentical blood groups [RR = 2(1.1–3.6); P = 0.02], arterial thrombosis [RR = 2.6(1.1–6.4); P = 0.02] and cold ischemia time longer than 430 min [RR = 1.8(1–3.2); P = 0.02] were risk factors for presenting BC.
Conclusion Liver transplantation using Rh graft–host nonidentical blood groups leads to a greater incidence of BC. 相似文献
193.
194.
Paula Vanessa Pedron Oltramari Ricardo de Lima Navarro José Fernando Castanha Henriques Rumio Taga Tania Mary Cestari Guilherme Janson José Mauro Granjeiro 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(5):e9-16
OBJECTIVE: The objective of this study was to radiographically quantify bone density and bone height preservation in tooth extraction alveolus filled with xenograft. STUDY DESIGN: The maxillary and mandibular fourth deciduous molars and fourth premolars of 6 minipigs were removed. Randomly, in 3 animals the right side was used as the test side and in the other 3 animals the left side was the test side. Intraoral radiographs were performed to compare the condition at the initial time and 3 months later. Measurements of bone height and bone density were performed using KS300 (Zeiss) software. RESULTS: After 3 months, there was a statistically significant smaller bone height loss for the test group. The test group presented a statistically greater bone density immediately after tooth extraction. However, after 3 months there was no statistically significant difference between the groups. CONCLUSIONS: The results suggest that treatment of postextraction alveolus with xenograft can preserve bone height initially but differences in bone density compared to when no xenograft is used are not sustained. 相似文献
195.
196.
R. J. Bosma A. J. Kwakernaak J. J. Homan van der Heide P. E. de Jong G. J. Navis 《American journal of transplantation》2007,7(3):645-652
Obesity is a risk factor for renal graft loss. Higher body mass index (BMI) in native kidneys is associated with glomerular hyperfiltration. Whether higher BMI in renal transplants is associated with hyperfiltration is unknown. We investigated the impact of BMI on renal hemodynamics 1 year post-transplant. We analyzed glomerular filtration rate (GFR, (125)I-iothalamate) and effective renal plasma flow (ERPF, (131)I-hippurate) in 838 kidney transplants. Data were analyzed for all patients and for the subpopulation without diabetes. Long-term impact of BMI and renal hemodynamics were explored by Cox-regression. With higher BMI GFR and filtration fraction (FF) increased significantly. Multivariate analysis supported impact of BMI on GFR (adjusted r(2) of the model 0.275) and FF (adjusted r(2) of the model 0.158). This association was not explained by diabetes mellitus. On Cox-regression analysis, lower GFR and higher FF were independent determinants of overall graft loss and graft loss by patient mortality. Lower GFR and higher BMI were determinants of death-censored graft loss, with borderline contribution of higher FF. In renal transplants higher BMI is independently associated with higher GFR and FF one year posttransplant, suggesting glomerular hyperfiltration with altered afferent-efferent balance. Mechanisms underlying the long-term prognostic impact of hyperfiltration deserve further exploration. 相似文献
197.
198.
199.
200.
We analyze whether the political system and its stability are related to cross-country differences in health. We apply factor analysis on various national health indicators for a large sample of countries over the period 2000–2005 and use the outcomes of the factor analysis to construct two new health measures, i.e., the health of individuals and the quality of the health care sector. Using a cross-country structural equation model with various economic and demographic control variables, we examine the relationship between the type of regime and political stability on the one hand and health on the other. The political variables and the control variables are measured as averages over the period 1980–1999. Our results suggest that democracy has a positive relationship with the health of individuals, while regime instability has a negative relationship with the health of individuals. Government instability is negatively related to individual health via its link with the quality of the health care sector, while democracy is positively related with individual health through its link with income. Our main findings are confirmed by the results of a panel model and various sensitivity tests. 相似文献