全文获取类型
收费全文 | 34759篇 |
免费 | 3598篇 |
国内免费 | 2492篇 |
专业分类
耳鼻咽喉 | 214篇 |
儿科学 | 476篇 |
妇产科学 | 395篇 |
基础医学 | 4262篇 |
口腔科学 | 636篇 |
临床医学 | 4481篇 |
内科学 | 5327篇 |
皮肤病学 | 313篇 |
神经病学 | 1571篇 |
特种医学 | 1162篇 |
外国民族医学 | 31篇 |
外科学 | 3759篇 |
综合类 | 6127篇 |
现状与发展 | 9篇 |
一般理论 | 3篇 |
预防医学 | 2341篇 |
眼科学 | 947篇 |
药学 | 3775篇 |
38篇 | |
中国医学 | 2077篇 |
肿瘤学 | 2905篇 |
出版年
2024年 | 137篇 |
2023年 | 642篇 |
2022年 | 1512篇 |
2021年 | 2129篇 |
2020年 | 1479篇 |
2019年 | 1252篇 |
2018年 | 1238篇 |
2017年 | 1152篇 |
2016年 | 1073篇 |
2015年 | 1609篇 |
2014年 | 1986篇 |
2013年 | 1782篇 |
2012年 | 2556篇 |
2011年 | 2834篇 |
2010年 | 1752篇 |
2009年 | 1393篇 |
2008年 | 1746篇 |
2007年 | 1852篇 |
2006年 | 1710篇 |
2005年 | 1622篇 |
2004年 | 1156篇 |
2003年 | 1118篇 |
2002年 | 982篇 |
2001年 | 788篇 |
2000年 | 766篇 |
1999年 | 767篇 |
1998年 | 443篇 |
1997年 | 464篇 |
1996年 | 354篇 |
1995年 | 343篇 |
1994年 | 328篇 |
1993年 | 178篇 |
1992年 | 228篇 |
1991年 | 228篇 |
1990年 | 237篇 |
1989年 | 184篇 |
1988年 | 153篇 |
1987年 | 117篇 |
1986年 | 120篇 |
1985年 | 93篇 |
1984年 | 71篇 |
1983年 | 40篇 |
1982年 | 27篇 |
1981年 | 22篇 |
1979年 | 20篇 |
1977年 | 16篇 |
1975年 | 14篇 |
1974年 | 19篇 |
1972年 | 13篇 |
1969年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Liver transplantation for hepatocellular carcinoma: analysis of factors predicting outcome in 1074 patients in OPTN Region 5 下载免费PDF全文
Brock Macdonald Justin L. Sewell Ann M. Harper John P. Roberts Francis Y. Yao 《Clinical transplantation》2015,29(6):506-512
Previous studies on loco‐regional therapy (LRT) and alpha‐fetoprotein (AFP) in predicting outcome after liver transplant (LT) for hepatocellular carcinoma (HCC) have shown inconsistent results. We analyzed the OPTN database in Region 5 from January 2004 to January 2009 and performed univariate and multivariate analysis of 11 pre‐transplant recipient and donor variables in 1074 patients with HCC meeting Milan criteria to detect association with post‐LT tumor recurrence or mortality. Mean waitlist time was 438 d. The 1‐ and 5‐yr post‐LT survival was 91.1% and 71.1%, respectively. In multivariate analysis, AFP before LT was the only predictor of HCC recurrence. The association between AFP and HCC recurrence was observed only in the subgroup receiving LRT but not in the subgroup without LRT. Predictors of mortality in multivariate analysis were HCC recurrence, Donor Risk Index, last AFP before LT, and MELD score. AFP before LT was the strongest predictor of post‐transplant HCC recurrence or death in multivariate analysis. In conclusion, in Region 5 with prolonged waitlist time, high AFP was the only pre‐transplant variable predicting post‐transplant tumor recurrence and mortality for HCC meeting Milan criteria. Our results also supported the importance of the effects of LRT on AFP in predicting prognosis. 相似文献
942.
Decreased Mechanical Strength and Collagen Content in SPARC‐Null Periodontal Ligament Is Reversed by Inhibition of Transglutaminase Activity 下载免费PDF全文
Jessica Trombetta‐eSilva Emilie A Rosset R Glenn Hepfer Gregory J Wright Catalin Baicu Hai Yao Amy D Bradshaw 《Journal of bone and mineral research》2015,30(10):1914-1924
The periodontal ligament (PDL) is a critical tissue that provides a physical link between the mineralized outer layer of the tooth and the alveolar bone. The PDL is composed primarily of nonmineralized fibrillar collagens. Expression of secreted protein acidic and rich in cysteine (SPARC/osteonectin), a collagen‐binding matricellular protein, has been shown to be essential for collagen homeostasis in PDL. In the absence of SPARC, PDL collagen fibers are smaller and less dense than fibers that constitute WT PDL. The aim of this study was to identify cellular mechanisms by which SPARC affected collagen fiber assembly and morphology in PDL. Cross‐linking of fibrillar collagens is one parameter that is known to affect insoluble collagen incorporation and fiber morphology. Herein, the reduction in collagen fiber size and quantity in the absence of SPARC expression was shown to result in a PDL with reduced molar extraction force in comparison to that of WT mice (C57Bl/6J). Furthermore, an increase in transglutaminase activity was found in SPARC‐null PDL by biochemical analyses that was supported by immunohistochemical results. Specifically, collagen I was identified as a substrate for transglutaminase in PDL and transglutaminase activity on collagen I was found to be greater in SPARC‐null tissues in comparison to WT. Strikingly, inhibition of transglutaminase activity in SPARC‐null PDL resulted in increases in both collagen fiber thickness and in collagen content, whereas transglutaminase inhibitors injected into WT mice resulted in increases in collagen fiber thickness only. Furthermore, PDL treated with transglutaminase inhibitors exhibited increases in molar extraction force in WT and in SPARC‐null mice. Thus, SPARC is proposed to act as a critical regulator of transglutaminase activity on collagen I with implications for mechanical strength of tissues. © 2015 American Society for Bone and Mineral Research 相似文献
943.
Evaluating the validity of model for end‐stage liver disease exception points for hepatocellular carcinoma patients with multiple nodules <2 cm 下载免费PDF全文
Mariya L. Samoylova Jennifer L. Dodge Neil Mehta Francis Y. Yao John P. Roberts 《Clinical transplantation》2015,29(1):52-59
Liver transplant allocation policy does not give model for end‐stage liver disease (MELD) exception points for patients with a single hepatocellular carcinoma (HCC) <2 cm in size, but does give points to patients with multiple small nodules. Because standard‐of‐care imaging for HCC struggles to differentiate HCC from other nodules, it is possible that a subset of patients receiving liver transplant for multiple nodules <2 cm in size does not have HCC. We evaluate risk of post‐transplant HCC recurrence and wait‐list dropout for patients with multiple small nodules using competing risks regression based on the Fine and Gray model. We identified 5002 adult HCC patients in the OPTN/UNOS dataset diagnosed and transplanted between January 2006 and September 2010. Compared to patients with >1 tumor <2 cm, risk of developing recurrence was significantly higher in patients with one or more tumors with only one tumor ≥2 cm (SHR 1.63, p = 0.009), as well as in patients with 2–3 tumors ≥2 cm (SHR 1.84, p = 0.02). Dropout risk was not significantly different among size categories. HCC recurrence risk was significantly lower in patients with multiple nodules <2 cm in size than in those with larger tumors, supporting the possibility that some patients received unnecessary transplants. The priority given to these patients must be re‐examined. 相似文献
944.
945.
Chunlong Chen Muhuo Ji Qian Xu Yao Zhang Qian Sun Jian Liu Sihai Zhu Weiyan Li 《Journal of anesthesia》2015,29(4):600-608
946.
947.
High neutrophil‐to‐lymphocyte ratio predicts poor clinical outcome in patients with castration‐resistant prostate cancer treated with docetaxel chemotherapy 下载免费PDF全文
948.
Robot‐assisted radical prostatectomy in an initial Japanese series: The impact of prior abdominal surgery on surgical outcomes 下载免费PDF全文
949.
Nan Yang He Liu Yao Jiang Ji Zheng Dong-mei Li Chao Ji Yan-yong Liu Ping-ping Zuo 《中国神经再生研究》2015,10(9):1457-1462
Lactulose is known to improve cognitive function in patients with early hepatic encephalopathy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and neurochemical effects of lactulose in a rat model of early hepatic encephalopathy induced by carbon tetrachloride. Immunohistochemistry showed that lactulose treatment promoted neurogenesis and increased the number of neurons and astrocytes in the hippocampus. Moreover, lactulose-treated rats showed shorter escape latencies than model rats in the Morris water maze, indicating that lactulose improved the cognitive impairments caused by hepatic encephalopathy. The present findings suggest that lactulose effectively improves cognitive function by enhancing neuroplasticity in a rat model of early hepatic encephalopathy. 相似文献
950.
Depression is a core symptom of methamphetamine (METH) withdrawal during the first several weeks of abstinence. However, the precise mechanisms underlying METH withdrawal symptoms remain unknown. Brain-derived neurotrophic factor (BDNF) and its specific receptor, tropomyosin-related kinase (TrkB), have a role the in pathophysiology of depression. In this study, we examined the role of BDNF–TrkB signaling in different brain regions of male mice with METH withdrawal symptoms. Repeated METH (3 mg kg−1 per day for 5 days) administration to mice caused a long-lasting depression-like behavior including anhedonia. Western blot analysis showed that BDNF levels in the nucleus accumbens (NAc) of METH-treated mice were significantly higher than those of control mice whereas BDNF levels in other regions, including the prefrontal cortex and hippocampus, were not altered. METH-induced depression-like behavior, behavioral sensitization and dendritic changes in the NAc shell were improved by subsequent subchronic administration of TrkB antagonist ANA-12 (0.5 mg kg−1 per day for 14 days), but not TrkB agonist 7,8-dihydroxyflavone (10 mg kg−1 per day for 14 days). In vivo microdialysis showed that METH (1 mg kg−1)-induced dopamine release in NAc shell of METH-treated mice was attenuated after subsequent subchronic ANA-12 administration. Interestingly, a single bilateral infusion of ANA-12 into the NAc shell, but not NAc core, showed a rapid and long-lasting therapeutic effect. However, ketamine and paroxetine had no effect. These findings suggest that increased BDNF–TrkB signaling in the NAc shell has an important role in the behavioral abnormalities after withdrawal from repeated METH administration, and that TrkB antagonists are potential therapeutic drugs for withdrawal symptoms in METH abusers. 相似文献