首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   14966篇
  免费   826篇
  国内免费   148篇
耳鼻咽喉   96篇
儿科学   321篇
妇产科学   223篇
基础医学   1691篇
口腔科学   377篇
临床医学   1293篇
内科学   4721篇
皮肤病学   179篇
神经病学   1478篇
特种医学   602篇
外科学   2139篇
综合类   26篇
预防医学   493篇
眼科学   132篇
药学   648篇
中国医学   9篇
肿瘤学   1512篇
  2023年   126篇
  2022年   213篇
  2021年   408篇
  2020年   283篇
  2019年   345篇
  2018年   407篇
  2017年   329篇
  2016年   403篇
  2015年   426篇
  2014年   591篇
  2013年   798篇
  2012年   1144篇
  2011年   1196篇
  2010年   660篇
  2009年   684篇
  2008年   1054篇
  2007年   1119篇
  2006年   1022篇
  2005年   989篇
  2004年   980篇
  2003年   799篇
  2002年   719篇
  2001年   91篇
  2000年   64篇
  1999年   95篇
  1998年   118篇
  1997年   120篇
  1996年   88篇
  1995年   81篇
  1994年   61篇
  1993年   73篇
  1992年   45篇
  1991年   55篇
  1990年   40篇
  1989年   22篇
  1988年   24篇
  1987年   26篇
  1986年   33篇
  1985年   21篇
  1984年   29篇
  1983年   23篇
  1982年   17篇
  1981年   15篇
  1980年   14篇
  1978年   9篇
  1977年   8篇
  1972年   7篇
  1968年   7篇
  1967年   10篇
  1966年   8篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Background. The maxillary sinus lift is a popular and predictable technique associated with implant-supported rehabilitation of the severely atrophic maxilla. The aim of the present retrospective study was to investigate the effectiveness of transcrestal maxillary sinus augmentation and the graft resorption pattern using different heterologous bone substitutes. Methods. A total of 75 sinus-grafting procedures were performed and 89 implants were placed in 66 patients, 24 males and 42 females, with mean age 67.9 ± 10.64 years (range 43–84 years). Nineteen subjects were smokers. The mean follow-up period was 93.33 ± 54.71 months (range 14–240 months). Clinical and radiographical evaluations were performed. Graft height and width were measured at baseline and at the latest follow-up. Results. Mesiodistal and vertical resorption averaged 9.3 ± 20.7% (standard deviation), and 5.04 ± 9.9% of the postoperative size, respectively, considering the graft as the unit. Linear regression analysis showed that graft resorption in both the vertical and the mesiodistal dimension is independent of the follow-up time. Conversely, there was a trend for greater resorption when increasing the postoperative graft size, in both vertical (p = 0.001) and horizontal (p = 0.007) dimensions. When grouping the dimensional changes by graft particle size (only small (<300 μm) particles, combination of small and medium (>500 μm)/large (>1000 μm) particles, and only medium/large particles), there was a trend for greater resorption associated with smaller particles, but it was not significant; neither in the mesiodistal nor in the vertical dimension (p = 0.17 and p = 0.25, respectively). No implant was lost during the observation period. In conclusion, the transcrestal technique for maxillary sinus augmentation documented a high level of predictability. The low clinical morbidity and the contextual dental implant positioning is clinically useful in relation to a significant reduction of the time required for implant restoration, a consistent decrease of the number of surgical phases, and a cost-effectiveness approach for the rehabilitation. The graft resorption pattern in all cases was compatible with persistent implant protection and support.  相似文献   
102.
103.
104.
The emergence of new influenza strains causing pandemics represents a serious threat to human health. From 1918, four influenza pandemics occurred, caused by H1N1, H2N2 and H3N2 subtypes. Moreover, in 1997 a novel influenza avian strain belonging to the H5N1 subtype infected humans. Nowadays, even if its transmission is still circumscribed to avian species, the capability of the virus to infect humans directly from avian reservoirs can result in fatalities. Moreover, the risk that this or novel avian strains could adapt to inter-human transmission, the development of resistance to anti-viral drugs and the lack of an effective prevention are all incumbent problems for the world population. In this scenario, the identification of broadly neutralizing monoclonal antibodies (mAbs) directed against conserved regions shared among influenza isolates has raised hopes for the development of monoclonal antibody-based immunotherapy and “universal” anti-influenza vaccines.  相似文献   
105.
introduction: Cancer of the testis is not always early detected and recognised, both by the physician and by the patient: sometimes physicians do not make an accurate genitals exam while patients often underestimate this problem. Case reports: Case I: 42-year-old man accepted from another hospital's Emergency, because of pain and edema of the right testis after a recent trauma on the gonad. At US, evidence of increased volume of the right testis with a large intraparenchymal hematoma. The markers were higher than normal. We performed a right orchiecthomy. The pathologist noted the presence of a mixed cancer of the testis (95% embryonal, 5% seminoma). Case II: 49-year-old man with hematuria, accepted from Emergency. The abdominal US revealed the presence of a voluminous neoformation (diameter of 12 cm) of the right kidney with neoplastic thrombosis of the right kidney vein. At the general physical exam, we detected the presence of an increased right testis, that at the US appared to be suspicious for cancer. Tumor markers were normal with the exception of αFP. We performed right nephro-adrenalectomy, right orchiectomy and removal of local nodes. The definitive histological examination demonstrated the presence of a seminoma of the testis and papillary carcinoma of the kidney with node metastasis. Discussion: Current studies showed an association between trauma and cancer of the testis, even if some authors did not find this association because they consider that patients with trauma undergo US and in that occasion cancer is incidentally detected. Conclusions: The association between trauma and cancer of the testis is controversial in current studies. Furthermore screening for the cancer of the testis does not seem to be useful, even if the self- and the physician's palpation of the testis seem to be very important because in these two cases they should allow the early detection of the condition, with a resulting better prognosis.  相似文献   
106.
107.
108.
109.
Telomerase is considered a universal tumor-associated antigen (TAA) due to its high rate of expression by cancers (approximately 90%), and clinical trials are in progress to test the immunotherapeutical efficacy of antitelomerase immunization in patients with cancer. However, the data concerning frequency and functional activity of telomerase-specific cytotoxic T lymphocytes (CTLs) in patients with cancer are few and conflicting, although their knowledge would be mandatory to predict the efficacy of telomerase-specific immunotherapy in selected patients. We performed this study to analyze frequency and cytolytic function of circulating CD8+ T lymphocytes specific for the p540 telomerase peptide in a series of human leukocyte antigen (HLA)-A2+ cancer patients. The results show that most patients with cancer have circulating telomerase-specific CD8+ T lymphocytes, but a high frequency of telomerase-specific CTLs are present only in a fraction of them. Furthermore, CTL lines able to kill telomerase-positive tumor cells, including autologous cancer cells, can be expanded ex vivo from some, but not all, patients with cancer. In conclusion, the results of the study support the development of clinical protocols using telomerase peptides as an immunizing agent. However, they underline the necessity to study single patients immunologically before undergoing vaccination, to select the patients adequately, and to eventually adapt the immunization schedule to the patient's immunologic status.  相似文献   
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号