全文获取类型
收费全文 | 260706篇 |
免费 | 23387篇 |
国内免费 | 10880篇 |
专业分类
耳鼻咽喉 | 3115篇 |
儿科学 | 5678篇 |
妇产科学 | 2828篇 |
基础医学 | 51715篇 |
口腔科学 | 6735篇 |
临床医学 | 19311篇 |
内科学 | 38026篇 |
皮肤病学 | 6548篇 |
神经病学 | 14944篇 |
特种医学 | 7029篇 |
外国民族医学 | 146篇 |
外科学 | 21589篇 |
综合类 | 37102篇 |
现状与发展 | 64篇 |
预防医学 | 8171篇 |
眼科学 | 4433篇 |
药学 | 24266篇 |
39篇 | |
中国医学 | 8300篇 |
肿瘤学 | 34934篇 |
出版年
2024年 | 575篇 |
2023年 | 3925篇 |
2022年 | 7278篇 |
2021年 | 9443篇 |
2020年 | 8268篇 |
2019年 | 8740篇 |
2018年 | 8993篇 |
2017年 | 9064篇 |
2016年 | 9052篇 |
2015年 | 10428篇 |
2014年 | 15058篇 |
2013年 | 16933篇 |
2012年 | 14511篇 |
2011年 | 16788篇 |
2010年 | 13843篇 |
2009年 | 13694篇 |
2008年 | 13686篇 |
2007年 | 13630篇 |
2006年 | 12372篇 |
2005年 | 11112篇 |
2004年 | 9921篇 |
2003年 | 8637篇 |
2002年 | 7089篇 |
2001年 | 5999篇 |
2000年 | 5121篇 |
1999年 | 4501篇 |
1998年 | 4235篇 |
1997年 | 3824篇 |
1996年 | 3363篇 |
1995年 | 3135篇 |
1994年 | 2703篇 |
1993年 | 2249篇 |
1992年 | 1774篇 |
1991年 | 1655篇 |
1990年 | 1335篇 |
1989年 | 1209篇 |
1988年 | 1068篇 |
1987年 | 891篇 |
1986年 | 850篇 |
1985年 | 1292篇 |
1984年 | 1319篇 |
1983年 | 892篇 |
1982年 | 972篇 |
1981年 | 783篇 |
1980年 | 660篇 |
1979年 | 533篇 |
1978年 | 386篇 |
1977年 | 322篇 |
1976年 | 321篇 |
1975年 | 185篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
N. E. McCarthy H. A. Jones N. A. Marks R. J. Shiner P. W. Ind H. O. Al-Hassi N. R. English C. M. Murray J. R. Lambert S. C. Knight A. J. Stagg 《Clinical and experimental allergy》2007,37(1):72-82
Background Dendritic cells (DC) mediate inflammation in rodent models of allergic airway disease, but the role played by human respiratory‐tract DC (hRTDC) in atopic asthma remains poorly defined. Recent data suggest that CD1 antigen presentation by hRTDC may contribute to asthma pathogenesis. Objective To investigate the influence of hRTDC on the balance between atopy and allergic asthma in human subjects and to determine whether CD1 expression by hRTDC is modulated during asthmatic inflammation. Methods Sputum cells were induced from steroid‐naïve, allergen‐challenged and allergen‐naïve subjects (atopic asthmatics, atopic non‐asthmatics and non‐atopic controls). hRTDC were identified using monoclonal antibody labelling and analysis by flow cytometry. Results hRTDC stained HLA‐DR+ (negative for markers of other cell lineages) were predominantly myeloid and comprised ∼0.5% of viable sputum cells. Sputum cells were potent stimulators of allogeneic CD4+ naïve T cells and enrichment/depletion experiments correlated stimulatory potency with DC numbers. Sputum contained cells that exhibited typical dendritic morphology when analysed by electron microscopy. Myeloid hRTDC were endocytically active, but uptake of FITC‐dextran was enhanced in cells from asthmatics (P<0.001). Despite their increased endocytic capacity, asthmatic myeloid hRTDC appeared mature and expressed increased levels of maturation markers (P<0.05–P<0.001), CD1c, CD1d and langerin (P<0.05). CD1c expression by asthmatic myeloid hRTDC was enhanced upon in vivo allergen challenge (three to ninefold within 24 h; P<0.05). CD11c−CD123high hRTDC were only detected in asthmatic sputum and were increased in number following allergen challenge. Conclusion Despite limited cell numbers, it proved possible to analyse human RTDC in induced sputum, providing evidence that increased antigen uptake and enhanced CD1 presentation by activated hRTDC may contribute to allergic airway disease. CD1 presentation by hRTDC in atopic asthma may therefore constitute a novel target for future intervention strategies. 相似文献
73.
Acute Cellular Rejection with CD20-Positive Lymphoid Clusters in Kidney Transplant Patients Following Lymphocyte Depletion 总被引:1,自引:0,他引:1
L. K. Kayler F. G. Lakkis C. Morgan A. Basu D. Blisard H. P. Tan J. McCauley C. Wu R. Shapiro P. S. Randhawa 《American journal of transplantation》2007,7(4):949-954
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup. 相似文献
74.
Atopy may be associated with a reduced T-cell function early in life, particularly regarding maturation of Th1 responses. The T-cell surface molecules CD2 and CD28 are involved in important T-cell activation pathways. Stimulation via the CD2 receptor increases the responsiveness to interleukin (IL)-12, which is a potent inducer of Th1 responses, whereas CD28 stimulation is critical for Th2 differentiation. Our aim was to prospectively study the expression of the cell-surface markers CD2 and CD28 on T-cells in relation to development of atopic disease. Children (n = 172) were followed from birth to 18 months and the cumulative history of atopic disease was recorded. Blood samples were obtained at birth and at 18 months, and in a subgroup of 78 infants also at 3, 6 and 12 months. Flow cytometry was used to analyze the T-cell markers CD2 and CD28, the latter also within the subsets of T-helper (CD4+) and T-cytotoxic (CD8+) cells. At 18 months, 31 children had and 118 did not have atopic symptoms. At this age, skin prick test (SPT) positive children with atopic symptoms with or without an atopic family history (AFH) showed a lower expression of CD2 mode fluorescence intensity (FI) as well as a lower proportion of CD2+ cells, as compared with non-sensitized children with neither atopic symptoms nor AFH. This was accompanied by a higher expression of CD28 FI on CD2+CD8+CD28+ cells. No significant differences were seen at time points before 18 months, although the proportion of CD2+ tended to be low also earlier in life. In conclusion, the observed reduced expression of CD2 in atopic infants may support previous findings that atopy is associated with a reduced CD2 function. The high CD28 FI in SPT positive children with atopic symptoms may possibly be a consequence of a TH2-skewed immune system. 相似文献
75.
76.
B Essers† F Nieman† M Prins† N Smeets‡ H Neumann§ 《Journal of the European Academy of Dermatology and Venereology》2007,21(9):1209-1214
BACKGROUND: Basal cell carcinoma (BCC) is a non-melanoma form of skin cancer that is frequently localized within the cervicofacial area. So far, little research is available on how patients perceive their facial aesthetics after surgical treatment for BCC. OBJECTIVES: To analyse (i) if there was a statistically significant improvement over time with regard to the perceived facial aesthetics of surgical patients; (ii) if there was a significant difference between primary and recurrent BCC patients; and (iii) between patients who had Mohs micrographic surgery (MMS) or surgical excision (SE). To assess (iv) which baseline perceptions and/or clinical parameters may predict the evaluation of facial aesthetics at 6 months after surgery. METHODS: Parallel to a clinical trial, a survey was carried out in which patients were asked, by means of a newly developed disease-specific questionnaire, about perceptions with regard to their facial aesthetics before and after surgery. RESULTS: Aesthetic perceptions of all surgical patients improved over time. There was no statistically significant difference on facial aesthetics between the group with a primary or recurrent BCC and patients treated with MMS or SE. Results also showed that the evaluation of postsurgical facial aesthetics can be predicted by both visibility of the tumour and preoperative perceptions. CONCLUSION: It is recommended to administer preoperatively a short questionnaire in which perceptions related to facial aesthetics are included. In doing so, physicians will become more familiar with the aesthetic problems patients might have regarding their afflicted facial site. Ultimately, it may help physicians in deciding whether patients will benefit from additional cosmetic procedures after surgery. 相似文献
77.
Ting-Kai Leung Chien-Jui Cheng Chi-Ming Lee Li-Kuo Shen Hung-Jung Wang Ya-Yen Chen 《中华医学杂志(英文版)》2005,118(17):1493-1496
The current report focuses on two patients of the same age who presented similar appearances on initial anteroposterior chest images. Follow-up images showed superoanterior and superoposterior mediastinal lesions. The first patient with noninvasive cystic thymoma was suspected before surgery, while the pathologic diagnosis was intrathoracic phrenic nerve schwannoma. The second patient was with an asymmetric, dumbbell-shaped paravertebral tumor over T3 and T4 on the left side. The preoperative… 相似文献
78.
Calcifying odontogenic cyst (COC) has shown to be of extensive diversity in its clinical and histopathological features, as well as in its biological behavior. In this report, a rare case is described of ameloblastoma ex COC (dentinogenic ghost cell tumor) and the relevant literature is briefly reviewed. 相似文献
79.
Mariana Villarroel Dorrego Paul M. Speight A. William Barrett 《Journal of oral pathology & medicine》2006,35(5):268-273
BACKGROUND: CD40 has a role in the regulation of immune responses, cell proliferation and migration, and apoptosis. Little is known of its distribution in oral mucosal pathology. METHODS: Oral keratinocyte lines were tested for CD40 protein by Western blotting. Immunohistochemistry was used to stain paraffin sections of oral mucosa in health and in inflammatory, reactive, dysplastic and malignant disease. RESULTS: Western blotting confirmed the presence of CD40 in oral keratinocytes. CD40 was generally expressed by keratinocytes in the basal layer, with variable parabasal expression. Langerhans cells also stained positively. Expression was lost in nine of 33 (27%) epithelial dysplasias, seven of which were severe. Eighty-one percent of well, 69% of moderately and 50% of poorly differentiated oral squamous cell carcinomas (OSCC) expressed CD40. Overall, 45 of 65 (69%) OSCC were positive. The pattern of expression was unrelated to tumour differentiation. CONCLUSION: CD40 expression by basal and parabasal oral keratinocytes is physiological. Expression is lost in approximately one-third of oral epithelial dysplasias and OSCC. The significance of such loss remains unknown, but may be related to immunological or other abnormalities of keratinocyte homeostasis. 相似文献
80.
Statin, a HMG-CoA reductase inhibitor, was shown to increase BMP-2 gene expression for bone formation, by blocking the mevalonate pathway in cholesterol production. We investigated the effect of naringin, a flavonoid available commonly in citrus fruits, which was also a HMG-CoA reductase inhibitor, in UMR 106 osteoblastic cell line in vitro. The control group consisted of cells cultured without any intervention for different time intervals (24 h, 48 h, and 72 h), whereas the experimental (naringin) group consisted of cells cultured with naringin of different concentrations (0.001 micromol/L, 0.01 micromol/L, and 0.1 micromol/L) for the same time intervals of the control. Colorimetric Tetrazolium (MTT) assay, total protein content assay, and alkaline phosphatase activity were used to measure the cellular activities. Results for the naringin group showed an increase in MTT assay compared with the control and the effect was dose dependent. At high concentration (0.1 micromol), the increases ranged from 60% to 80%. In the total protein content assay, naringin also showed an increase compared with control and the effect was also dose dependent. At high concentration (0.1 micromol), the increases ranged from 9% to 20%. In the alkaline phosphatase activity assay, naringin at high concentration (0.1 micromol) significantly increased the activity up to 20%. In conclusion, naringin significantly increased bone cell activities in vitro. This is the first study specifically attempted to investigate the effect of naringin on bone cell activities. Besides statin, this provided another example of mevalonate pathway blockage in the cholesterol production pathway by HMG-CoA reductase inhibition will increase the bone cell activities. 相似文献