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   1508篇
  免费   65篇
  国内免费   10篇
耳鼻咽喉   5篇
儿科学   16篇
妇产科学   18篇
基础医学   143篇
口腔科学   13篇
临床医学   126篇
内科学   516篇
皮肤病学   27篇
神经病学   128篇
特种医学   94篇
外科学   129篇
综合类   7篇
预防医学   43篇
眼科学   9篇
药学   64篇
中国医学   3篇
肿瘤学   242篇
  2023年   18篇
  2022年   22篇
  2021年   43篇
  2020年   27篇
  2019年   35篇
  2018年   43篇
  2017年   38篇
  2016年   33篇
  2015年   32篇
  2014年   49篇
  2013年   32篇
  2012年   72篇
  2011年   79篇
  2010年   39篇
  2009年   45篇
  2008年   78篇
  2007年   89篇
  2006年   67篇
  2005年   82篇
  2004年   77篇
  2003年   98篇
  2002年   67篇
  2001年   46篇
  2000年   42篇
  1999年   22篇
  1998年   12篇
  1997年   10篇
  1996年   16篇
  1995年   14篇
  1994年   19篇
  1993年   12篇
  1992年   19篇
  1991年   24篇
  1990年   16篇
  1989年   12篇
  1988年   30篇
  1987年   19篇
  1986年   26篇
  1985年   14篇
  1984年   7篇
  1983年   9篇
  1982年   6篇
  1979年   4篇
  1977年   3篇
  1976年   7篇
  1974年   3篇
  1972年   3篇
  1971年   3篇
  1970年   4篇
  1969年   3篇
排序方式: 共有1583条查询结果,搜索用时 46 毫秒
991.
992.
Hematopoietic stem cells (HSCs) are a subset of bone marrow cells that are capable of self-renewal and of giving rise to all types of blood cells. However, the mechanisms involved in controlling the number and abilities of HSCs remain largely unknown. The Indian hedgehog (Ihh) signal has an essential role in inducing hematopoietic tissue during embryogenesis. We investigated the roles of the Ihh in coculture with CD34+ cells and human stromal cells. Ihh mRNA was expressed in primary and telomerized human (hTERT) stromal cells, and its receptor molecules were detected in CD34+ cells. Ihh gene transfer into hTERT stromal cells enhanced their hematopoietic supporting potential, which was elevated compared with control stromal cells, as indicated by the colony-forming units in culture (CFU-Cs) (26-fold +/- 2-fold versus 59-fold +/- 3-fold of the initial cell number; mixed colony-forming units [CFU-Mix's], 63-fold +/- 37-fold versus 349-fold +/- 116-fold). Engraftments of nonobese diabetic/severe combined immunodeficiency-beta2m-/- (NOD/SCID-beta2-/-) repopulating cells (RCs) expanded on Ihh stromal cells were significantly higher compared with control coculture results, and engraftment was neutralized by addition of an antihedgehog antibody. Limiting dilution analysis indicated that NOD/SCID-beta2m-/- RCs proliferated efficiently on Ihh stromal cells, compared with control stromal cells. These results indicate that Ihh gene transfer could enhance the primitive hematopoietic support ability of human stromal cells.  相似文献   
993.
A 48-year-old woman, who had been suffering from systemic lupus erythematosus (SLE), developed normochromic normocytic anemia after receiving clomipramine hydrochloride. Her reticulocyte count was low, and a bone marrow aspirate revealed erythroid hypoplasia without involvement of other cell lines. Thus a diagnosis of pure red cell aplasia (PRCA) was made. The anemia gradually resolved following withdrawal of the drug. Although several drugs are known to cause PRCA, this is the first time that clomipramine hydrochloride has been reported to have such an effect. The underlying SLE in this case suggested the possible immunological pathogenesis of drug-induced PRCA.  相似文献   
994.
995.
The aim of the present study was to investigate the feasibility of measuring metabolic tumor burden using [F‐18] fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT) in patients with relapsed or refractory diffuse large B‐cell lymphoma (DLBCL) treated with bendamustine–rituximab. Because the standardized uptake value is a critical parameter of tumor characterization, we carried out a phantom study of 18F‐FDG PET/CT to ensure quality control for 28 machines in the 24 institutions (Japan, 17 institutions; Korea, 7 institutions) participating in our clinical study. Fifty‐five patients with relapsed or refractory DLBCL were enrolled. The 18F‐FDG PET/CT was acquired before treatment, after two cycles, and after the last treatment cycle. Treatment response was assessed after two cycles and after the last cycle using the Lugano classification. Using this classification, remission was complete in 15 patients (27%) and incomplete in 40 patients (73%) after two cycles of therapy, and remission was complete in 32 patients (58%) and incomplete in 23 patients (42%) after the last treatment cycle. The percentage change in all PET/CT parameters except for the area under the curve of the cumulative standardized uptake value–volume histogram was significantly greater in complete response patients than in non‐complete response patients after two cycles and the last cycle. The Cox proportional hazard model and best subset selection method revealed that the percentage change of the sum of total lesion glycolysis after the last cycle (relative risk, 5.24; P = 0.003) was an independent predictor of progression‐free survival. The percent change of sum of total lesion glycolysis, calculated from PET/CT, can be used to quantify the response to treatment and can predict progression‐free survival after the last treatment cycle in patients with relapsed or refractory DLBCL treated with bendamustine–rituximab.  相似文献   
996.
997.
Histamine is highly concentrated in the heart of animals and humans. Excessive release in pathophysiological conditions, such as immediate hypersensitivity and septic shock, causes cardiac dysfunction and arrhythmias. Previous pharmacological studies revealed that H(1) and H(2) receptors mediate these effects. Yet, an accurate estimate of the distribution and molecular characteristics of cardiac histamine receptors is missing. Recently, the genes encoding H(1) and H(2) receptors have been cloned, and the amino acid sequence and protein structure have been elucidated. Accordingly, we analyzed gene and protein expression levels of H(1) and H(2) receptors in atria and ventricles of guinea pig, rabbit, rat, and human hearts. With immunocytochemical techniques, we examined the regional expression of H(1) and H(2) receptor proteins in the sinoatrial and atrioventricular nodes and surrounding myocardium of the guinea pig heart. Northern and Western blot studies revealed that cardiac histamine H(1) and H(2) receptors are variably distributed among different mammalian species and different regions of the heart, whereas H(2) receptors are abundantly expressed in human atrial and ventricular myocardium. These findings agree with those of previous pharmacological studies, clearly demonstrating that the responses of the heart to histamine depend on the expression level of H(1) and H(2) receptors. The highly abundant expression of H(2) receptors in the human heart substantiates histamine arrhythmogenicity in various disease states. The new knowledge of a differential distribution of histamine receptor subtypes in the human heart will foster a better understanding of histamine roles in cardiovascular pathophysiology and may contribute to new therapeutic approaches to histamine-induced cardiac dysfunctions.  相似文献   
998.
We investigated the implication of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in the proliferation stimulated by angiotensin II (Ang II) and endothelin-1 (ET-1) in cultured rabbit gingival fibroblasts (CRGF). Ang II stimulated activation of ERK1/2 and the activation was inhibited by CV-11974, an AT1 antagonist, and saralasin, an AT1/AT2 antagonist, but not by PD123,319, an AT2 antagonist in the CRGF. Ang II-stimulated proliferation was inhibited by PD98059 or U0126, selective MEK inhibitors. Furthermore, ET-1 stimulated proliferation via G-protein-coupled ETA receptors, which were identified by Western blot analysis of membrane protein from the CRGF. ET-1 also stimulated activation of ERK1/2 and the activation was inhibited by BQ-123, an ETA inhibitor, and TAK044, an ETA/ETB inhibitor, but not by BQ-788, an ETB inhibitor. ET-1-stimulated proliferation was inhibited by PD98059 or U0126. These findings suggest that ERK1/2 play a role in the signaling process leading to proliferation stimulated by Ang II and ET-1 via G-protein-coupled receptors, AT1 and ETA in CRGF.  相似文献   
999.

Background

Very few studies have investigated the association between diabetes and impaired health-related quality of life (HRQOL) in older adults, independent of chronic conditions and geriatric syndromes.

Methods

We conducted a self-administered questionnaire survey and structured interviews with 3946 people aged 65 years or older to obtain medical histories of diabetes, chronic conditions, and geriatric syndromes. Blood tests were performed to measure glycated hemoglobin (HbA1c) and plasma glucose levels. HRQOL was evaluated using the Medical Outcomes Study 36-Item Short-Form General Health Survey (SF-36), and multiple logistic regression analysis was used to calculate adjusted odds ratios and 95% CIs for low HRQOL.

Results

A total of 3521 participants had not received a physician diagnosis of diabetes. Of these, 2345 participants with an HbA1c less than 5.7% were defined as the referent group. As compared with the referent group, 1029 participants with an HbA1c of at least 5.7% but less than 6.5% showed no significant decrease in QOL on the SF-36 physical, mental, and role component summaries, after adjustment for chronic conditions, geriatric syndromes, and other potential confounders. However, 572 patients who had received a physician diagnosis of diabetes and/or had an HbA1c of 6.5% or higher had a significantly higher adjusted odds ratio (1.48; 95% CI, 1.18–1.84) for the low physical component summary. No significant differences in relation to glycemic control, treatment regimen, or diabetes duration were found in any of the 3 component summaries among the 425 participants who were undergoing diabetes treatment.

Conclusions

Older Japanese adults with diabetes had decreased physical QOL, independent of chronic conditions and geriatric syndromes.Key words: diabetes, older adults, geriatric syndromes, chronic conditions, SF-36  相似文献   
1000.
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