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   440519篇
  免费   32420篇
  国内免费   1781篇
耳鼻咽喉   4875篇
儿科学   11545篇
妇产科学   8587篇
基础医学   57555篇
口腔科学   8833篇
临床医学   43436篇
内科学   93145篇
皮肤病学   5911篇
神经病学   42589篇
特种医学   14619篇
外国民族医学   24篇
外科学   67910篇
综合类   6681篇
现状与发展   2篇
一般理论   592篇
预防医学   39023篇
眼科学   10529篇
药学   30011篇
  6篇
中国医学   718篇
肿瘤学   28129篇
  2023年   1867篇
  2022年   3075篇
  2021年   8495篇
  2020年   5086篇
  2019年   8244篇
  2018年   9454篇
  2017年   7300篇
  2016年   7951篇
  2015年   9423篇
  2014年   14009篇
  2013年   19812篇
  2012年   29613篇
  2011年   31525篇
  2010年   17829篇
  2009年   16045篇
  2008年   28797篇
  2007年   30374篇
  2006年   29714篇
  2005年   30139篇
  2004年   28512篇
  2003年   26686篇
  2002年   25208篇
  2001年   3896篇
  2000年   3010篇
  1999年   4246篇
  1998年   5614篇
  1997年   4760篇
  1996年   4199篇
  1995年   3868篇
  1994年   3355篇
  1993年   3095篇
  1992年   2407篇
  1991年   2244篇
  1990年   2027篇
  1989年   1897篇
  1988年   1952篇
  1987年   1936篇
  1986年   1917篇
  1985年   2026篇
  1984年   2611篇
  1983年   2511篇
  1982年   3063篇
  1981年   2844篇
  1980年   2622篇
  1979年   1500篇
  1978年   1668篇
  1977年   1535篇
  1976年   1392篇
  1975年   1140篇
  1974年   1108篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
31.
Abstract

Objective

Ras wild-type metastatic colorectal cancers (mCRC) may be treated with anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor receptor (EGFR) agents. We aim to estimate patients’ preferences for mCRC treatment and relative importance of cost, efficacy improvement, avoidance of side effects and therapy convenience, and relative uptake between profiles that resemble Bevacizumab (anti-VEGF) and Cetuximab (anti-EGFR), two commonly prescribed mCRC targeted therapies.  相似文献   
32.
33.
34.
Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.  相似文献   
35.
36.
37.
The aim of the study was to determine the effect of β-glucan on the cytotoxicity and genotoxicity of polypectomized patient's fecal water (FW). Polypectomized volunteers (n = 69) were randomly assigned to consume bread with or without β-glucan, for 3 months. FW was collected at the beginning (t = 0), the 30th and 90th day and 2 wk after the intervention. Cytotoxicity and genotoxicity were estimated on Caco-2 cells, using trypan blue exclusion test and comet assay, respectively. Gastrointestinal symptoms were recorded and subjects kept a 3-day food diary at baseline and after completion. Trypan blue exclusion test revealed cell survival of approximately 87% after incubation with FW. The FW samples showed 49% genotoxicity at the baseline. Genotoxicity in the intervention group decreased during the trial reaching statistical significance on the 90th day compared to control. An increase was noticed 2 wk after the trial, but it still remained significantly lower compared to control. Group-specific analysis for β-glucan also revealed significant decrease in the genotoxicity on the 90th day compared to baseline. β-glucan ingestion in polypectomized patients significantly decreased the genotoxicity of their FW. Our findings suggest that β-glucan consumption could possibly provide protection against colon cancer development.  相似文献   
38.
The present narrative review examines the scientific evidence of the biological mechanisms that may link periodontitis and diabetes, as a source of comorbidity. Publications regarding periodontitis and diabetes, in human, animals, and in vitro were screened for their relevance. Periodontal microbiome studies indicate a possible association between altered glucose metabolism in prediabetes and diabetes and changes in the periodontal microbiome. Coinciding with this, hyperglycemia enhances expression of pathogen receptors, which enhance host response to the dysbiotic microbiome. Hyperglycemia also promotes pro-inflammatory response independently or via the advanced glycation end product/receptor for advanced glycation end product pathway. These processes excite cellular tissue destruction functions, which further enhance pro-inflammatory cytokines expression and alteration in the RANKL/osteoprotegerin ratio, promoting formation and activation of osteoclasts. The evidence supports the role of several pathogenic mechanisms in the path of true causal comorbidity between poorly controlled diabetes and periodontitis. However, further research is needed to better understand these mechanisms and to explore other mechanisms.  相似文献   
39.
Reactive lymphoid infiltrates of the skin composed predominantly of gamma‐delta (γδ) T cells are not well described in the literature. Herein we report a case of an otherwise healthy 4‐year‐old male who presented with a waxing and waning papular rash characterized by small, discrete crusted papules spread across his trunk, face and extremities. Clinical evaluation revealed no evidence of systemic disease. Microscopic examination revealed a dermal, perivascular infiltrate of highly atypical lymphocytes with a γδ T cell phenotype, worrisome for primary cutaneous γδ T cell lymphoma. The clinical course, however, was that of a reactive condition and prompted consideration of a diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP). In many ways, this case defies current classification schemes and seems to expand the spectrum of reactive γδ T cell infiltrates of the skin.  相似文献   
40.
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