全文获取类型
收费全文 | 1400篇 |
免费 | 195篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 95篇 |
妇产科学 | 116篇 |
基础医学 | 267篇 |
口腔科学 | 7篇 |
临床医学 | 91篇 |
内科学 | 523篇 |
皮肤病学 | 45篇 |
神经病学 | 116篇 |
特种医学 | 28篇 |
外科学 | 80篇 |
综合类 | 12篇 |
一般理论 | 1篇 |
预防医学 | 36篇 |
眼科学 | 11篇 |
药学 | 45篇 |
肿瘤学 | 118篇 |
出版年
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 29篇 |
2020年 | 36篇 |
2019年 | 35篇 |
2018年 | 67篇 |
2017年 | 46篇 |
2016年 | 51篇 |
2015年 | 36篇 |
2014年 | 43篇 |
2013年 | 66篇 |
2012年 | 95篇 |
2011年 | 89篇 |
2010年 | 44篇 |
2009年 | 34篇 |
2008年 | 75篇 |
2007年 | 73篇 |
2006年 | 57篇 |
2005年 | 84篇 |
2004年 | 77篇 |
2003年 | 66篇 |
2002年 | 50篇 |
2001年 | 29篇 |
2000年 | 17篇 |
1999年 | 21篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 21篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1992年 | 18篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1971年 | 8篇 |
1969年 | 9篇 |
排序方式: 共有1597条查询结果,搜索用时 15 毫秒
61.
The ability to convey our thoughts using an infinite number of linguistic expressions is one of the hallmarks of human language. Understanding the nature of the psychological mechanisms and representations that give rise to this unique productivity is a fundamental goal for the cognitive sciences. A long-standing hypothesis is that single words and rules form the basic building blocks of linguistic productivity, with multiword sequences being treated as units only in peripheral cases such as idioms. The new millennium, however, has seen a shift toward construing multiword linguistic units not as linguistic rarities, but as important building blocks for language acquisition and processing. This shift—which originated within theoretical approaches that emphasize language learning and use—has far-reaching implications for theories of language representation, processing, and acquisition. Incorporating multiword units as integral building blocks blurs the distinction between grammar and lexicon; calls for models of production and comprehension that can accommodate and give rise to the effect of multiword information on processing; and highlights the importance of such units to learning. In this special topic, we bring together cutting-edge work on multiword sequences in theoretical linguistics, first-language acquisition, psycholinguistics, computational modeling, and second-language learning to present a comprehensive overview of the prominence and importance of such units in language, their possible role in explaining differences between first- and second-language learning, and the challenges the combined findings pose for theories of language. 相似文献
62.
63.
Ronen Arnon Rachel Annunziato Michael Schilsky Tamir Miloh Asha Willis Mark Sturdevant Arnond Sakworawich Frederick Suchy Nanda Kerkar 《Clinical transplantation》2011,25(1):E52-E60
Arnon R, Annunziato R, Schilsky M, Miloh T, Willis A, Sturdevant M, Sakworawich A, Suchy F, Kerkar N. Liver transplantation for children with Wilson disease: comparison of outcomes between children and adults.Clin Transplant 2011: 25: E52–E60. © 2010 John Wiley & Sons A/S. Abstract: Liver transplantation (LT) is lifesaving for patients with Wilson disease (WD) presenting with fulminant hepatic failure (FHF) or chronic liver disease (CLD) unresponsive to treatment. Aim: To determine the outcome of LT in pediatric and adult patients with WD. Methods: United Network for Organ Sharing data on LT from 1987 to 2008 were analyzed. Outcomes were compared for patients requiring LT for FHF and CLD after 2002. Multivariate logistic regression was used to determine risk factors for death and graft loss. Results: Of 90 867 patients transplanted between 1987 and 2008, 170 children and 400 adults had WD. The one‐ and five‐yr patient survival of children was 90.1% and 89% compared to 88.3% and 86% for adults, p = 0.53, 0.34. After 2002, 103 (41 children) were transplanted for FHF and 67 (10 children) for CLD. One‐ and five‐yr patient survival was higher in children transplanted for CLD compared to FHF; 100%, 100% vs. 90%, 87.5% respectively, p = 0.30, 0.32. One‐ and five‐yr patient survival was higher in adults transplanted for CLD compared to FHF; 94.7%, 90.1% vs. 90.3%, 89.7%, respectively, p = 0.36, 0.88. Encephalopathy, partial graft, and ventilator use were risk factors for death by logistic regression. Conclusion: LT is an excellent treatment option for patients with WD. Patients transplanted for CLD had higher patient survival rates than patients with FHF. 相似文献
64.
Adam Zaidel MSc Alexander Spivak MD Lavi Shpigelman PhD Hagai Bergman MD PhD Zvi Israel MD 《Movement disorders》2009,24(12):1785-1793
Positive therapeutic response without adverse side effects to subthalamic nucleus deep brain stimulation (STN DBS) for Parkinson's disease (PD) depends to a large extent on electrode location within the STN. The sensorimotor region of the STN (seemingly the preferred location for STN DBS) lies dorsolaterally, in a region also marked by distinct beta (13–30 Hz) oscillations in the parkinsonian state. In this study, we present a real‐time method to accurately demarcate subterritories of the STN during surgery, based on microelectrode recordings (MERs) and a Hidden Markov Model (HMM). Fifty‐six MER trajectories were used, obtained from 21 PD patients who underwent bilateral STN DBS implantation surgery. Root mean square (RMS) and power spectral density (PSD) of the MERs were used to train and test an HMM in identifying the dorsolateral oscillatory region (DLOR) and nonoscillatory subterritories within the STN. The HMM demarcations were compared to the decisions of a human expert. The HMM identified STN‐entry, the ventral boundary of the DLOR, and STN‐exit with an error of ?0.09 ± 0.35, ?0.27 ± 0.58, and ?0.20 ± 0.33 mm, respectively (mean ± standard deviation), and with detection reliability (error < 1 mm) of 95, 86, and 91%, respectively. The HMM was successful despite a very coarse clustering method and was robust to parameter variation. Thus, using an HMM in conjunction with RMS and PSD measures of intraoperative MER can provide improved refinement of STN entry and exit in comparison with previously reported automatic methods, and introduces a novel (intra‐STN) detection of a distinct DLOR‐ventral boundary. © 2009 Movement Disorder Society 相似文献
65.
Immunosuppressives have been used in multiple sclerosis (MS) since 1966. Today, we have many treatments for the relapsing forms of the disease, including 8 US Food and Drug Administration-approved therapies, with more soon to be introduced. Given the current treatment landscape what place do immunosuppressants have in combating MS? Trial work and our experience suggest that immunosuppressives still have an important role in treating MS. Cyclophosphamide finds use in treating patients with severe, inflammatory relapsing remitting MS or those suffering from a fulminant attack. We tend to employ mycophenolate mofetil as an add-on to injectable therapy for patients experiencing breakthrough activity. Some progressive (primary progressive multiple sclerosis or secondary progressive multiple sclerosis) patients may stabilize after treatment with either cyclophosphamide or mycophenolate. We rarely employ mitoxantrone because of potential cardiac or carcinogenic effects. We prefer to use cyclophosphamide or mycophenolate mofetil in preference to methotrexate because evidence of efficacy is limited for this drug. We have less experience with azathioprine, but it may be an alternative for patients with limited options who are unable to tolerate conventional therapies. 相似文献
66.
Karni A Balashov K Hancock WW Bharanidharan P Abraham M Khoury SJ Weiner HL 《Journal of neuroimmunology》2004,146(1-2):189-198
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system considered to be mediated by T helper type-1 cells. Several agents have been found to modify the disease course of MS, including interferon-beta1 (IFN-beta1), glatiramer acetate mitoxantrone. We have employed pulse therapy with cyclophosphamide in a selected group of patients with actively progressive disease. Chemokine receptors have been found to differentiate between polarized T helper type-1 (Th1) and type-2 (Th2) lymphocytes. The chemokine receptors CCR5 and CXCR3 are expressed primarily on Th1 cells and CCR3, CCR4 and CCR8 on Th2 cells. Previous studies of the expression of chemokine receptors in MS have shown that active MS plaques are infiltrated by CCR5(+) and CXCR3(+) T cells. Some of these T cells may express both CCR5 and CXCR3. These T cells are major producers of IFN-gamma, which worsens the clinical condition of patients with MS. We previously found that patients with MS had a high proportion of CXCR3(+) T cells and that those with chronic progressive MS had a high proportion of CCR5(+) T cells in their peripheral blood. We report here that in patients with secondary progressive MS, cyclophosphamide induces a marked increase in the percentage of CCR4(+) T cells that produce high levels of IL-4 and reverses the increase in the percentages of IFN-gamma-producing CCR5(+) and CXCR3(+) CD8(+) T cells. Furthermore, therapy with cyclophosphamide increases IL-4-producing CD4(+) T cells and reverses the increase in IFN-gamma-producing CD8(+) T cells. Our study shows that cyclophosphamide has immunomodulatory properties besides its suppressive effects, and that chemokine receptors can be important tools both for understanding the immune dysregulation in MS and for monitoring response to therapy. 相似文献
67.
Oren J. Becher M.D. Mark Souweidane M.D. † Ehud Lavi M.D. ‡ Kim Kramer M.D. Eric Lis M.D. § Ashfaq A. Marghoob M.D. ¶ Yasmin Khakoo M.D. 《Pediatric dermatology》2009,26(1):79-82
Abstract: A 14-day-old boy presented with a large congenital melanocytic nevus over his left thigh with approximately 17 satellite nevi distributed over the rest of his skin surface. Six weeks later, he developed generalized tonic–clonic seizures and additional satellite nevi became apparent ( n > 20). A subsequent brain magnetic resonance imaging demonstrated right temporal T1 hyperintense signal abnormality. At 4 months of age the patient underwent a lumbar puncture that was normal without evidence of melanocytes or tumor. Nevertheless, a few days later he underwent resection of his right medial temporal lesion which demonstrated melanocytosis in the temporal lobe as well as melanocytosis in subependymal areas in other parts of the brain and ventricles, confirming the suspected diagnosis of neurocutaneous melanocytosis. Our case supports previous studies that conclude that the number of satellite nevi is a greater predictor of neurocutaneous melanocytosis than is the location of large congenital melanocytic nevus. In our case, cerebrospinal fluid studies were not reliable even in the face of florid neurocutaneous melanocytosis involving the leptomeninges and ventricles. 相似文献
68.
69.
Growth inhibition of prostate cancer xenografts by halofuginone 总被引:3,自引:0,他引:3
BACKGROUND: Halofuginone, an inhibitor of collagen type I synthesis, is an anti-angiogenic agent. Here we evaluated the efficacy of halofuginone to inhibit prostate cancer (PC) xenografts representing various phenotypes of the disease. METHODS: An androgen-dependent (CWR22), an androgen-independent (PC3), and a neuroendocrine (WISH-PC2) PC xenograft were used. Halofuginone was given orally or injected intraperitoneally. Tumor size, collagen alpha1(I) gene expression (in situ hybridization), collagen content (sirius red staining), angiogenesis (immunohistochemistry with factor VIII antibodies), and apoptosis/necrosis (DNA fragmentation) were evaluated. RESULTS: Halofuginone inhibited the growth of all subcutaneously implanted xenografts and of WISH-PC2 when transplanted orthotopically. The effect was dose-dependent (WISH-PC2) and accompanied by decrease in plasma PSA levels (CWR22). In all xenografts, halofuginone inhibited collagen alpha1(I) gene expression, reduced collagen content, and endothelial cell number resulting in an increase in apoptosis/necrosis. CONCLUSIONS: Oral administration of halofuginone slowed the progression of PC xenografts representing a broad range of phenotypes. Halofuginone may become a new modality for PC prevention. 相似文献
70.
Cohen AD Grunwald MH Avinoach I Halevy S 《Journal of the American Academy of Dermatology》2003,49(4):729-730
Trichodiscomas are hamartomas of the hair disk and appear as multiple, firm, well-circumscribed papules measuring a few millimeters. In most cases, trichodiscomas are distributed on the face and neck. Trichodiscomas may occur as isolated tumors or in association with other follicular tumors. In some cases, multiple trichodiscomas appear in association with fibrofolliculomas or acrochordons. We herein describe multiple agminated trichodiscomas in the earlobe. 相似文献