全文获取类型
收费全文 | 189870篇 |
免费 | 7723篇 |
国内免费 | 562篇 |
专业分类
耳鼻咽喉 | 2535篇 |
儿科学 | 5349篇 |
妇产科学 | 4286篇 |
基础医学 | 27562篇 |
口腔科学 | 6376篇 |
临床医学 | 11548篇 |
内科学 | 42094篇 |
皮肤病学 | 5151篇 |
神经病学 | 15398篇 |
特种医学 | 4823篇 |
外国民族医学 | 1篇 |
外科学 | 21369篇 |
综合类 | 815篇 |
一般理论 | 33篇 |
预防医学 | 21976篇 |
眼科学 | 4822篇 |
药学 | 14694篇 |
中国医学 | 801篇 |
肿瘤学 | 8522篇 |
出版年
2023年 | 1066篇 |
2022年 | 1217篇 |
2021年 | 3534篇 |
2020年 | 2022篇 |
2019年 | 3669篇 |
2018年 | 5815篇 |
2017年 | 3711篇 |
2016年 | 3891篇 |
2015年 | 4372篇 |
2014年 | 5020篇 |
2013年 | 7295篇 |
2012年 | 12382篇 |
2011年 | 12979篇 |
2010年 | 6549篇 |
2009年 | 4917篇 |
2008年 | 10487篇 |
2007年 | 11063篇 |
2006年 | 10518篇 |
2005年 | 9979篇 |
2004年 | 9192篇 |
2003年 | 8475篇 |
2002年 | 8019篇 |
2001年 | 4995篇 |
2000年 | 5534篇 |
1999年 | 4246篇 |
1998年 | 861篇 |
1992年 | 2262篇 |
1991年 | 2031篇 |
1990年 | 2009篇 |
1989年 | 1718篇 |
1988年 | 1631篇 |
1987年 | 1519篇 |
1986年 | 1571篇 |
1985年 | 1475篇 |
1984年 | 1068篇 |
1983年 | 908篇 |
1979年 | 1214篇 |
1978年 | 811篇 |
1977年 | 786篇 |
1976年 | 744篇 |
1975年 | 879篇 |
1974年 | 1121篇 |
1973年 | 1166篇 |
1972年 | 1112篇 |
1971年 | 1076篇 |
1970年 | 1007篇 |
1969年 | 1083篇 |
1968年 | 1105篇 |
1967年 | 977篇 |
1966年 | 880篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Melatonin reduces oxidative stress and improves vascular function in pulmonary hypertensive newborn sheep
下载免费PDF全文
![点击此处可从《Journal of pineal research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Flavio Torres Alejandro González‐Candia Camilo Montt Germán Ebensperger Magdalena Chubretovic María Serón‐Ferré Roberto V. Reyes Aníbal J. Llanos Emilio A. Herrera 《Journal of pineal research》2015,58(3):362-373
Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial‐ and muscular‐dependent pathways. This was associated with an enhanced nitric oxide‐dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN. 相似文献
13.
14.
15.
Anastasiia Panfilova Sarah E. Shelton Cristina Caresio Ruud J.G. van Sloun Filippo Molinari Hessel Wijkstra Paul A. Dayton Massimo Mischi 《Ultrasound in medicine & biology》2019,45(2):539-548
Dynamic contrast-enhanced ultrasound (DCE-US) has been proposed as a powerful tool for cancer diagnosis by estimation of perfusion and dispersion parameters reflecting angiogenic vascular changes. This work was aimed at identifying which vascular features are reflected by the estimated perfusion and dispersion parameters through comparison with acoustic angiography (AA). AA is a high-resolution technique that allows quantification of vascular morphology. Three-dimensional AA and 2-D DCE-US bolus acquisitions were used to monitor the growth of fibrosarcoma tumors in nine rats. AA-derived vascular properties were analyzed along with DCE-US perfusion and dispersion to investigate the differences between tumor and control and their evolution in time. AA-derived microvascular density and DCE-US perfusion exhibited good agreement, confirmed by their spatial distributions. No vascular feature was correlated with dispersion. Yet, dispersion provided better cancer classification than perfusion. We therefore hypothesize that dispersion characterizes vessels that are smaller than those visible with AA. 相似文献
16.
17.
Paula Cristina Galati Paula Garcia Chiarello Belinda Pinto Simões 《Nutrition and cancer》2016,68(1):86-93
Changes in resting energy expenditure (REE) of cancer patients vary depending on type of tumor, treatment time point and kind of treatment. Little is known about REE of acute leukemia adult patients after treatment, especially with results related to body weight or fat free mass (FFM). This study aimed to assess changes in REE of acute leukemia adult patients before and after the first remission induction. Evaluation of REE was performed by indirect calorimetry and predicted REE was calculated by Harris-Benedict equation. Weight and height were measured and compared to a control group of healthy individuals. FFM was assessed by bioelectrical impedance for adjusting REE values. We evaluated 18 patients and 26 healthy individuals. At diagnosis, patients presented REE, REE/weight, and REE/FFM higher than the controls. Reductions of REE, REE/weight, and REE/FFM were also observed in patients after the first cycle of chemotherapy. The predicted REE for the patients group showed significant lower value compared with measured REE. Before the first cycle of chemotherapy REE was increased but undergoes a reduction after treatment, reaching values similar to the controls. For predictive Harris-Benedict equation, stress factors should be added to avoid underestimation of REE before and after chemotherapy. 相似文献
18.
19.
Yolanda Carrascal PhD Gregorio Laguna PhD Miriam Blanco MD Bárbara Segura MD Iciar Martínez-Almeida MD 《Journal of cardiac surgery》2020,35(2):457-459
Gray platelet syndrome (GPS) is a rare (<1/1 000 000) and inherited platelet function disorder characterized by macrothrombocytopenia, α-granule deficiency, and hemorrhages. Bleeding intensity does not correlate with platelet count nor with functional test results. We hereby describe the perioperative bleeding prevention and management of a patient with GPS requiring multiple redo cardiac surgeries. 相似文献
20.
Ángela M. Ortega-Galán M. Dolores Ruiz-Fernández Rocío Ortiz-Amo José Cabrera-Troya Inés M. Carmona-Rega Olivia Ibáñez-Masero 《Enfermería clínica》2019,29(1):10-17