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   9573篇
  免费   563篇
  国内免费   47篇
耳鼻咽喉   124篇
儿科学   158篇
妇产科学   50篇
基础医学   1283篇
口腔科学   223篇
临床医学   785篇
内科学   2277篇
皮肤病学   158篇
神经病学   557篇
特种医学   459篇
外国民族医学   1篇
外科学   1557篇
综合类   57篇
一般理论   1篇
预防医学   260篇
眼科学   400篇
药学   695篇
中国医学   30篇
肿瘤学   1108篇
  2023年   56篇
  2022年   122篇
  2021年   200篇
  2020年   116篇
  2019年   144篇
  2018年   207篇
  2017年   160篇
  2016年   191篇
  2015年   201篇
  2014年   276篇
  2013年   306篇
  2012年   454篇
  2011年   498篇
  2010年   265篇
  2009年   252篇
  2008年   469篇
  2007年   489篇
  2006年   489篇
  2005年   440篇
  2004年   494篇
  2003年   455篇
  2002年   453篇
  2001年   311篇
  2000年   287篇
  1999年   262篇
  1998年   129篇
  1997年   96篇
  1996年   80篇
  1995年   74篇
  1994年   89篇
  1993年   65篇
  1992年   182篇
  1991年   170篇
  1990年   179篇
  1989年   168篇
  1988年   162篇
  1987年   119篇
  1986年   110篇
  1985年   147篇
  1984年   97篇
  1983年   72篇
  1982年   41篇
  1981年   39篇
  1980年   44篇
  1979年   68篇
  1978年   51篇
  1975年   37篇
  1971年   37篇
  1970年   40篇
  1969年   42篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
A case of multicentric malignant fibrous histiocytoma of the stomach and small intestine is reported. The patient was a 60-year-old man who had total gastrectomy under an impression of a gastric carcinoma. The resected stomach revealed a large polypoid mass in the antral portion at the greater curvature. Three months later, he developed ileus and an 80 cm segment of the jejunum was removed. It contained two polypoid masses identical to that seen in the stomach. The tumors showed, in addition to the characteristic light microscopic appearances, strong positivity for alpha-1-antitrypsin by an immunoperoxidase technique, indicating the diagnosis of malignant fibrous histiocytoma (MFH). Electron microscopic findings were also consistent with MFH. We believe that this is the first well-documented case of MFH arising from the stomach and small intestine, to the best of our knowledge.  相似文献   
112.
In order to investigate the effects of acute hypoxia and accompanying hypocapnia on the ventilatory response at the onset of dynamic exercise, four healthy adult men performed 50W rectangular loads on a cycle-ergometer in normoxic (FIO2 = 0.21) and hypoxic (FIO2 = 0.11) conditions. No statistically significant differences in the initial ventilatory responses to exercise (both delta VI and delta VE assessed on a breath-by-breath basis) were found between eucapnic normoxia (PETO2 approximately 95, PETCO2 approximately 42 Torr) and hypocapnic hypoxia (PETO2 approximately 45, PETCO2 approximately 35 Torr). The present findings support the contention that the neurogenic ventilatory drive at the onset of early exercise is independent from PO2 and PCO2.  相似文献   
113.
In this study, we demonstrate that Porphyromonas gingivalis fimbriae use molecules of β2 integrin (CD11/CD18) on mouse peritoneal macrophages as cellular receptors and also show that the β chain (CD18) may play a functional role in signalling for the fimbria-induced expression of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) genes in the cells. Using a binding assay with 125I-labeled fimbriae, we observed that fimbrial binding to the macrophages was inhibited by treatment with CD11a, CD11b, CD11c, or CD18 antibody but not by that with CD29 antibody. Western blot assays showed that the fimbriae bound to molecules of β2 integrin (CD11/CD18) on the macrophages. Furthermore, Northern blot analyses showed that the fimbria-induced expression of IL-1β and TNF-α genes in the cells was inhibited strongly by CD18 antibody treatment and slightly by CD11a, CD11b, or CD11c antibody treatment. Interestingly, intracellular adhesion molecule 1 (ICAM-1), a ligand of CD11/CD18, inhibited fimbrial binding to the cells in a dose-dependent manner. In addition, ICAM-1 clearly inhibited the fimbria-induced expression of IL-1β and TNF-α genes in the cells. However, such inhibitory action was not observed with laminin treatment. These results suggest the importance of β2 integrin (CD11/CD18) as a cellular receptor of P. gingivalis fimbriae in the initiation stage of the pathogenic mechanism of the organism in periodontal disease.  相似文献   
114.
PD-1 and its ligands, B7-H1/PD-L1 and B7-DC/PD-L2, have been identified recently as CD28-B7 family molecules that are implicated in immune regulation. Lichen planus (LP) is a T cell-mediated chronic inflammatory mucocutaneous disease. We investigated the expression and function of PD-1 and its two ligands in LP. Immunohistochemical examination revealed the abundant expression of PD-1 and B7-H1 in infiltrating T cells and macrophages, and lower-level expression of B7-DC on macrophages in the subepithelium. Interestingly, substantial expression of B7-H1 on keratinocytes (KCs) was found close to the numerous T cell infiltrates in the subepithelium. Unstimulated cultured KCs expressed both B7-H1 and B7-DC, and their expression was upregulated by proinflammatory cytokines, particularly IFN-gamma. The T-cell proliferative responses and IFN-gamma production that were induced by IFN-gamma-treated KCs were augmented preferentially by anti-B7-H1 mAb, but not by anti-B7-DC mAb. These results indicate the regulatory role of B7-H1 on KCs in the interactions with T cells. Our results suggest that the induction of B7-H1 on KCs may play an important role in tolerance induction in the inflamed oral mucosa and skin.  相似文献   
115.
116.
M Ishida  K Doi  L N Loo  C E Metz  J L Lehr 《Radiology》1984,150(2):569-575
Detection studies of simulated low-contrast radiographic patterns were performed with a high-quality digital image processing system. The original images, prepared with conventional screen-film systems, were processed digitally to enhance contrast by a "windowing" technique. The detectability of simulated patterns was quantified in terms of the results of observer performance experiments by using the multiple-alternative forced-choice method. The processed images demonstrated a significant increase in observer detection performance over that for the original images. These results are related to the displayed and perceived signal-to-noise ratios derived from signal detection theory. The improvement in detectability is ascribed to a reduction in the relative magnitude of the human observer's "internal" noise after image processing. The measured dependence of threshold signal contrast on object size and noise level is accounted for by a statistical decision theory model that includes internal noise.  相似文献   
117.
Neurosurgical Review - The present study aimed to determine the incidence of intraprocedural motor-evoked potential (MEP) changes and to correlate them with intraprocedural ischemic complications...  相似文献   
118.
119.
PurposeThe aim of this study was to assess the association between the implementation of abdominal angiography and outcome among pediatric patients with blunt splenic or hepatic injury.MethodsThis was a retrospective observational study, with a study period of 14 years, from January 2004 to December 2017. Blunt-trauma patients with splenic or hepatic injury who were less than 19 years old were included in this study. We used propensity-score-(PS) matching analysis to assess the relationship between abdominal angiography and in-hospital mortality.ResultsIn total, 639 patients were eligible for analysis, with 257 patients included in the abdominal-angiography group and 382 patients in the no-abdominal-angiography group. After PS matching, 224 patients from each group were selected. In the PS matched patients, in-hospital mortality was lower in the abdominal-angiography group than in the no-abdominal-angiography group (4.9% vs. 11.2%, odds ratio 0.416, 95% confidence interval 0.177–0.903).ConclusionIn this population, the implementation of abdominal angiography was significantly associated with lower in-hospital mortality among pediatric patients with blunt splenic or hepatic injury compared with nonimplementation of abdominal angiography.Type of studyPrognosis study.Level of evidenceIII  相似文献   
120.
Clinical and Experimental Nephrology - The data regarding oncological outcome in advanced renal cell carcinoma (RCC) arising in end-stage renal disease (ESRD) are limited. Patients diagnosed with...  相似文献   
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