全文获取类型
收费全文 | 55577篇 |
免费 | 2672篇 |
国内免费 | 414篇 |
专业分类
耳鼻咽喉 | 579篇 |
儿科学 | 1081篇 |
妇产科学 | 1534篇 |
基础医学 | 6769篇 |
口腔科学 | 2551篇 |
临床医学 | 4167篇 |
内科学 | 14979篇 |
皮肤病学 | 1078篇 |
神经病学 | 4892篇 |
特种医学 | 1409篇 |
外科学 | 8246篇 |
综合类 | 225篇 |
一般理论 | 12篇 |
预防医学 | 3389篇 |
眼科学 | 972篇 |
药学 | 3046篇 |
中国医学 | 174篇 |
肿瘤学 | 3560篇 |
出版年
2024年 | 42篇 |
2023年 | 416篇 |
2022年 | 1035篇 |
2021年 | 1898篇 |
2020年 | 1067篇 |
2019年 | 1474篇 |
2018年 | 1947篇 |
2017年 | 1271篇 |
2016年 | 1366篇 |
2015年 | 1696篇 |
2014年 | 2305篇 |
2013年 | 2950篇 |
2012年 | 4448篇 |
2011年 | 4569篇 |
2010年 | 2520篇 |
2009年 | 2160篇 |
2008年 | 3741篇 |
2007年 | 3818篇 |
2006年 | 3578篇 |
2005年 | 3476篇 |
2004年 | 3090篇 |
2003年 | 2730篇 |
2002年 | 2415篇 |
2001年 | 378篇 |
2000年 | 289篇 |
1999年 | 368篇 |
1998年 | 415篇 |
1997年 | 358篇 |
1996年 | 331篇 |
1995年 | 304篇 |
1994年 | 244篇 |
1993年 | 184篇 |
1992年 | 183篇 |
1991年 | 134篇 |
1990年 | 122篇 |
1989年 | 103篇 |
1988年 | 85篇 |
1987年 | 73篇 |
1986年 | 88篇 |
1985年 | 92篇 |
1984年 | 88篇 |
1983年 | 84篇 |
1982年 | 102篇 |
1981年 | 71篇 |
1980年 | 78篇 |
1979年 | 49篇 |
1978年 | 54篇 |
1977年 | 42篇 |
1976年 | 40篇 |
1975年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The performance of a tooth replacement by using a dental implant relies on the mechanical and biological capability of the anatomical substitute to restore lost physiological functions. The design of an implant device able to properly replace the physiological tooth requires the study of the load transfer mechanism at the implant-bone interface and the understanding of the relevance of the periodontal ligament (PDL) in this mechanism. The PDL is a connective soft tissue that provides the fixation of the tooth in its bone-socket and the attenuation of occlusal loads. It also provides the ground cells that are involved in the remodelling process, induced by a change in the stress-strain pattern of the alveolar bone and also in the cementum of the tooth root. The purpose of this study was to determine the PDL effects on the dynamic load transfer mechanism, from the tooth to the alveolar bone, evaluating the equivalent dynamic stiffness of the ligament structure. A porcine fresh mandible with a tooth was used within the study, applying an experimental procedure to identify the dynamic transmissibility of the entire system. The transmissibility function provided information about the stiffness and damping of the PDL, information that can assist the design of an improved dental implant system. 相似文献
12.
Pyroglutamyl, proline-rich oligopeptides, classically referred to as bradykinin-potentiating peptides (BPPs) are found in Bothrops jararaca venom, and are naturally occurring inhibitors of the somatic angiotensin-converting enzyme (ACE). The chemical and pharmacological properties of these peptides were essential for the development of captopril, the first active site directed inhibitor of ACE, currently used to treat human hypertension. ACE is a complex ectoenzyme of the vascular endothelium, possessing two catalytic sites, performing diverse specific roles. Recent advances concerning novel features of BPPs revealed that they might still contribute to a better understanding of the cardiovascular physiology and pathology. The molecular biology of the BPPs revealed that they are part of two distinct C-type natriuretic peptide precursors found in the venom gland and the brain of B. jararaca, each containing seven BPPs. In situ hybridization studies detected the presence of the corresponding mRNA precursor in snake brain regions correlated with neuroendocrine functions, such as the ventro-medial hypothalamus, the paraventricular nuclei, the paraventricular organ, and the subcommissural organ. In this article we discuss the large variety of homologous BPPs in B. jararaca venom and brain, its significance, and whether the BPPs could represent novel endogenous neuropeptides. 相似文献
13.
Antonio Gómez Mercedes Salgado Manuel Valladares-Ayerbes Mónica Jorge Ana Carballo Sonia Candamio Pilar Izquierdo Paula Peleteiro Rafael López 《Clinical & translational oncology》2010,12(12):843-848
Objective
The aim of the project was to assess the effectiveness and safety of weekly epoetin-beta (EB) in patients with gastrointestinal cancer (GIC) subjected to concomitant chemoradiotherapy (CCTRT). 相似文献14.
Carlos Ferrer Albiach Antonio Conde Moreno Marta Rodríguez Cordón Virginia Morillo Macías Ana Bouché Babiloni Inmaculada Beato Tortajada Ángel Sánchez Iglesias Alicia Francés Muñoz 《Clinical & translational oncology》2010,12(1):22-26
Hypoxia is related to poor prognosis because it is associated to chemo-and radioresistance. During recent years the evolution
of imaging methods like PET/CT and MRI has meant the appearance of new perspectives with direct implications in radiation
therapy. We discuss previous experiences in staging, planning and in the follow-up process with these techniques for measuring
tumour hypoxia. 相似文献
15.
16.
Estrella Fernández Fabrellas Luis Almenar Bonet Silvia Ponce Pérez José Antonio Moro López Rafael Blanquer Olivas Antonio Salvador Sanz 《Archivos de bronconeumologia》2009,45(4):173-180
Introduction and objectiveWhen sleep apnea-hypopnea syndrome (SAHS) and cardiovascular disease occur concurrently, prognosis is affected. Echocardiography can detect structural cardiac abnormalities but using this technique in all patients would place a heavy burden on resources. The objective of this study was to investigate whether the N-terminal fraction of brain natriuretic peptide (NT-proBNP) can be used as a marker for silent heart disease.Patients and methodsNT-proBNP concentration was measured in the 114 consecutive patients with SAHS who underwent echocardiography before starting treatment. Left and right ventricular systolic and diastolic function, as well as structural abnormalities, were studied. Correlations between NT-proBNP concentration and the abnormalities detected were investigated. A receiver operating characteristics (ROC) curve was plotted for NT-proBNP concentration and cardiac abnormalities.ResultsData for 98 patients were finally analyzed. NT-proBNP concentration was significantly correlated with ventricular septal thickness (r=0.63), posterior wall thickness (r=0.45), and left ventricular enddiastolic diameter (r=0.51) (P<.0001 for all correlations). The area under the ROC curve was significant (0.870; 95% confidence interval, 0.801-0.939; P<.0001). Assuming that specificity would be more useful for clinical practice, we calculated that NT-proBNP concentrations below 100 and 200 pg/mL could rule out structural abnormalities with a reliability of 90% and 100%, respectively.ConclusionsNT-proBNP concentration was strongly correlated with echocardiographic abnormalities and so could be a useful tool for identifying patients who should be referred to the cardiologist. 相似文献
17.
18.
Marco Antonio Palma Rocio Ortiz Carlos Alvarez-Dardet Maria T. Ruiz 《Social science & medicine (1982)》2009
The possible effect of Government Consumption (a component of Gross Domestic Product (GDP)) on attainment of the hunger Millennium Development Goal (MDG1) was analyzed by evaluating the effect of macroeconomic, social, demographic and policy variables on average undernourished population. Eighty-four developing countries with data available on undernourished population were included in an ecological study. Regression models were applied to explore possible determinants of Undernourished between 1990 and 2004 and consequent achievement of the projected 2004 MDG1. In 2004, 1.4% of the overall undernourished population in the studied countries [70.16 million people] was in excess of the projected level required to meet MDG1. The multiple linear regression showed significant associations between Undernourished and poverty levels, the Gini Index, rural population and Government Consumption. The multiple logistic regression showed significant associations between achievement of projected 2004 MDG1 levels and Government Consumption and the Gini Index. The significant associations between Undernourished and Government Consumption suggest that the effects of GDP components on social conditions call for more thorough research and that policymakers such as governments and international financial institutions need to ensure that changes in distributive and redistributive policies do not negatively affect the possibility of achieving MDG1. 相似文献
19.
Antonio E Martin-Ucar Apostolos Nakas John G Edwards David A Waller 《European journal of cardio-thoracic surgery》2007,31(5):765-70; discussion 770-1
OBJECTIVE: To compare the outcomes of extrapleural pneumonectomy (EPP) and radical pleurectomy/decortication (P/D) for N2 malignant pleural mesothelioma (MM). PATIENTS AND METHODS: In a retrospective case-control study we analysed the results of the 57 patients [49 male and 8 female, median age 59 (range 14-70) years] who underwent radical surgery for MM found to have pathological N2 disease over a 7-year-period. EPP was performed on 45 and P/D on 12 patients. Prognostic factors, postoperative course, pathological data and postoperative survival were analysed. RESULTS: Those in the P/D group were significantly older (median age 62 vs 58 years, p=0.03) than in the EPP group. There was no difference in postoperative hospital stay (p=0.1) nor T stage (p=0.7) between the groups. There were no significant differences in the proportion of patients undergoing some adjuvant therapy in each group (p=0.2). Mean survival from diagnosis was 15 months in the EPP group and 16 months for those who underwent P/D (p=0.4). CONCLUSIONS: Preservation of the lung during radical surgery for N2 MM does not compromise survival even in an older group population. We therefore now have ceased to perform EPP in cases of N2 disease and we make every effort to accurately stage patients with mediastinoscopy to identify them. 相似文献
20.
L Crespo J Graus F García-Hoz R Bárcena L Gil Grande V F Moreira J M Milicua J Sánchez J Blázquez 《Revista española de enfermedades digestivas》2007,99(11):667-670
Hepatic encephalopathy is a reversible state of altered cognition that may occur in patients with acute or chronic liver disease or porto-systemic shunt, and in which known neurological or psychiatric signs may develop. Nitrogenated substances from intestinal digestion reach the brain without being cleared by their passage through the liver due to the presence of porto-systemic shunt. We report two cases of patients with porto-systemic shunt diagnosed with recurrent chronic hepatic encephalopathy refractory to conventional medical treatment. They were satisfactorily treated with shunt embolization using interventionist radiology techniques. 相似文献