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   6215篇
  免费   344篇
  国内免费   33篇
耳鼻咽喉   69篇
儿科学   156篇
妇产科学   71篇
基础医学   759篇
口腔科学   156篇
临床医学   392篇
内科学   1387篇
皮肤病学   429篇
神经病学   464篇
特种医学   518篇
外科学   810篇
综合类   20篇
预防医学   189篇
眼科学   178篇
药学   361篇
中国医学   18篇
肿瘤学   615篇
  2023年   34篇
  2022年   55篇
  2021年   106篇
  2020年   79篇
  2019年   104篇
  2018年   120篇
  2017年   110篇
  2016年   110篇
  2015年   130篇
  2014年   194篇
  2013年   223篇
  2012年   330篇
  2011年   425篇
  2010年   187篇
  2009年   159篇
  2008年   345篇
  2007年   337篇
  2006年   368篇
  2005年   330篇
  2004年   309篇
  2003年   307篇
  2002年   317篇
  2001年   164篇
  2000年   151篇
  1999年   194篇
  1998年   77篇
  1997年   68篇
  1996年   61篇
  1995年   51篇
  1994年   52篇
  1993年   45篇
  1992年   117篇
  1991年   117篇
  1990年   89篇
  1989年   76篇
  1988年   96篇
  1987年   78篇
  1986年   61篇
  1985年   87篇
  1984年   66篇
  1983年   34篇
  1982年   21篇
  1981年   17篇
  1979年   20篇
  1978年   20篇
  1977年   19篇
  1973年   12篇
  1970年   14篇
  1968年   18篇
  1966年   12篇
排序方式: 共有6592条查询结果,搜索用时 31 毫秒
1.
2.
The aim of this study was to evaluate whether the lesion regression rate (ΔLR) based on the Response Evaluation Criteria in Solid Tumors (RECIST) criteria could be used for the prediction of treatment outcome in head and neck squamous cell carcinoma (HNSCC) patients treated with chemoradiotherapy (CRT) compared with FDG PET-CT. A total of 33 patients underwent MRI and PET-CT at pretreatment and at 8 weeks after CRT. We assessed the treatment outcome by analyzing the following parameters: the RECIST criteria, ΔLR, the European Organization for Research and Treatment of Cancer (EORTC) criteria, and pretreatment SUVmax of the primary tumor and node. The correlation between the analysis of the parameters and the results of the long-term follow-up of the patients was determined. The RECIST did not significantly correlate with locoregional control (LRC) or survival. The ΔLR was significantly lower for the lesions with locoregional failure (LRF) than for those with LRC. A threshold ΔLR of 48% revealed a sensitivity of 72.7% and specificity of 77.3% for the prediction of LRF. Progression-free survival (PFS) of patients with ΔLR ≥ 48% was significantly better than that of patients with ΔLR < 48% (P = 0.001), but not overall survival. There was a significant correlation between LRC and the EORTC (P = 0.02). The patients who achieved a complete response by the EORTC criteria showed significantly better PFS and overall survival (P = 0.01 and 0.04, respectively). The ΔLR was inferior to FDG PET-CT with respect to the prediction of patient survival; however, it may be useful for selecting patients in need of more aggressive monitoring after CRT.  相似文献   
3.
We report an 80-year-old Japanese male with four primary malignant tumors: malignant melanoma, prostatic cancer, malignant lymphoma, and renal cell carcinoma, which occurred in that respective order. The combination of malignant melanoma and malignant lymphoma is rare. The patient was treated with BCG after an operation for malignant melanoma. He was also treated with cobalt 60 irradiation after an operation for prostatic cancer. We also discuss other reports of multiple malignant tumors and suggest some possible causes of this patient's primary malignant tumors.  相似文献   
4.
Big mitogen-activated protein kinase 1 (BMK1), also known as extracellular signal-regulated kinase 5 (ERK5), is a newly identified member of the mitogen-activated protein (MAP) kinase family. Recently, several studies have suggested that BMK1 plays an important role in the pathogenesis of cardiovascular disease. To clarify the pathophysiological significance of BMK1 in the process of vascular remodeling, we explored the molecular mechanisms of BMK1 activation in vascular smooth muscle cells (VSMCs). From the results of co-immunoprecipitation and immunoblotting analyses, it was found that platelet-derived growth factor (PDGF), a known potent mitogen, activated BMK1 and triggered the Gab1-SHP-2 interaction in rat aortic smooth muscle cells (RASMCs). The abrogation of SHP-2 phosphatase activity by transfection of the SHP-2-C/S mutant suppressed PDGF-stimulated BMK1 activation. Infection with an adenoviral vector expressing dominant-negative MEK5alpha, which can suppress PDGF-stimulated BMK1 activation to the control level, inhibited PDGF-induced RASMC migration. Moreover, we observed an increase of BMK1 activation in injured mouse femoral arteries. From these findings, it is suggested that BMK1 activation leads to VSMC migration induced by PDGF via Gab1-SHP-2 interaction, and that BMK1-mediated VSMC migration may play a role in the pathogenesis of vascular remodeling.  相似文献   
5.
6.
7.
In order to investigate the possibility that the theory of two-stage carcinogenesis can be applied to neurogenic carcinogenesis, we analyzed the promoting effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the in vitro malignant transformation of fetal rat brain cells exposed in utero to ethylnitrosourea (ENU). Rat brain cells were transferred to a cultured system at 72 h after a single pulse of ENU (50 mg/kg body weight) to pregnant SD-JCL rats on the 18th day of gestation. The positive findings of glial fibrillary acidic protein and S-100 protein in primary cultured cells by the analysis of immunohistochemistry revealed the neuroglial origin of transformed cells. These cells were divided into 12 groups and were treated twice per week with or without TPA at concentrations from 0.1 to 50.0 ng/ml. From the results of cellular morphology, Concanavalin A agglutinability, colony forming capacity in semisolid soft agar, and tumorigenicity in vivo, malignant transformation of fetal rat brain cells appeared earlier in the ENU group treated with TPA than in the untreated ENU group. On the basis of these observations, it is suggested that TPA might be effective as a tumor promoter on ENU-induced neurogenic carcinogenesis.  相似文献   
8.
9.
BACKGROUND: Myocardial perfusion single photon emission computed tomography (SPECT) occasionally fails to detect coronary stenosis in patients with coronary artery disease (CAD). We evaluated coronary flow reserve (CFR) using oxygen 15-labeled water in areas with and without ischemia on technetium 99m tetrofosmin stress perfusion SPECT in patients with angiographically documented CAD. METHODS AND RESULTS: Twenty-seven patients with CAD and eleven age-matched normal subjects were studied. Baseline myocardial blood flow (MBF) and MBF during hyperemia induced by intravenous adenosine triphosphate infusion (0.16 mg. kg(-1). min(-1)) were determined with the use of O-15-labeled water positron emission tomography, and the CFR was calculated. Tc-99m tetrofosmin stress/rest SPECT was performed for comparison. On the basis of the results of coronary angiography and SPECT, coronary segments were divided into 3 types: segments with coronary stenosis and a perfusion abnormality on stress SPECT imaging (group A, n = 16), segments with coronary stenosis without a perfusion abnormality (group B, n = 42), and remote segments with no coronary stenosis or perfusion abnormality (group C, n = 18). Baseline MBF values were similar among the 3 groups. CFR in group A was lower (1.82 +/- 0.54) than in group B (2.22 +/- 0.87, P <.05), in group C (2.92 +/- 1.21, P <.01), and in normal segments (3.86 +/- 1.24, P <.001). CFR in group B was lower than in group C (P <.02) and in normal segments (P <.001). CFR in group C was lower than in normal segments (P <.02). CONCLUSIONS: Areas with a perfusion abnormality on stress SPECT had reduced CFR. In the areas without a perfusion abnormality and with coronary stenosis, lowering of CFR was intermediate between the areas with a perfusion abnormality and remote segments. Moreover, CFR was slightly, but significantly, lower in remote segments in patients with CAD compared with normal segments.  相似文献   
10.
The medial globus pallidus plays a crucial role in generation of L‐DOPA‐induced dyskinesia in patients with Parkinson's disease. The 6‐hydroxydopamine‐lesioned rat exhibiting behavioral sensitization to L‐DOPA is one useful animal model for examining L‐DOPA‐induced dyskinesia. To determine neuropathological abnormality responsible for behavioral sensitization, the medial globus pallidus and the substantia nigra reticulata in 6‐hydroxydopamine‐lesioned rats treated with L‐DOPA were examined. Intermittent L‐DOPA treatment induced hypertrophy of the lesioned‐side of medial globus pallidus and substantia nigra reticulata of 6‐hydroxydopamine‐lesioned rats with behavioral sensitization to L‐DOPA. Additionally, coadministration of a 5‐HT1A receptor agonist, 8‐hydroxy‐2(di‐n‐propylamino)tetralin with L‐DOPA, alleviated the hypertrophy with improvement of the behavioral sensitization. These results suggest that hypertrophy of the medial globus pallidus and substantia nigra reticulata is associated with induction of behavioral sensitization to L‐DOPA in 6‐hydroxydopamine‐lesioned rats. Therefore, neuropathological changes corresponding to hypertrophy might underlie L‐DOPA‐induced dyskinesia in patients with Parkinson's disease.  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