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   249858篇
  免费   57870篇
  国内免费   11895篇
耳鼻咽喉   3049篇
儿科学   6695篇
妇产科学   2219篇
基础医学   32562篇
口腔科学   8123篇
临床医学   35667篇
内科学   44974篇
皮肤病学   9264篇
神经病学   20085篇
特种医学   8916篇
外国民族医学   71篇
外科学   27495篇
综合类   35708篇
现状与发展   53篇
一般理论   35篇
预防医学   19276篇
眼科学   6031篇
药学   25806篇
  255篇
中国医学   14019篇
肿瘤学   19320篇
  2024年   817篇
  2023年   2870篇
  2022年   7329篇
  2021年   10542篇
  2020年   12358篇
  2019年   16103篇
  2018年   15598篇
  2017年   17328篇
  2016年   17202篇
  2015年   20060篇
  2014年   21998篇
  2013年   22764篇
  2012年   19384篇
  2011年   20372篇
  2010年   20373篇
  2009年   14551篇
  2008年   12786篇
  2007年   11149篇
  2006年   10342篇
  2005年   8839篇
  2004年   6325篇
  2003年   6158篇
  2002年   5154篇
  2001年   4208篇
  2000年   3399篇
  1999年   2580篇
  1998年   1403篇
  1997年   1322篇
  1996年   935篇
  1995年   1001篇
  1994年   774篇
  1993年   459篇
  1992年   567篇
  1991年   456篇
  1990年   374篇
  1989年   359篇
  1988年   304篇
  1987年   257篇
  1986年   217篇
  1985年   135篇
  1984年   76篇
  1983年   64篇
  1982年   37篇
  1981年   42篇
  1980年   32篇
  1979年   40篇
  1977年   21篇
  1974年   18篇
  1973年   23篇
  1972年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
腺苷与异丙酚预处理对犬心肌缺血再灌注损伤的保护作用   总被引:2,自引:0,他引:2  
目的探讨腺苷与异丙酚预处理对犬心肌缺血再灌注损伤的保护作用。方法 21只杂种犬,雌雄不拘,随机分为3组(n=7):缺血再灌注组(A组)、异丙酚预处理组(B组)、异丙酚与腺苷联合预处理组(C组)。A组冠状动脉的左前降支结扎60min后松开结扎,再灌注:120min;B组缺血前30min经静脉以5.6mg·kg-1·h-1速率持续泵注异丙酚30min;C组缺血前10min经主动脉根部一次性注入腺苷(10mmol·L-1,10ml),其余处理同B组。记录心脏血液动力学指标,并行节段性室壁运动评分(RWMS)。结果缺血即刻出现了缺血性心电图的变化。与基础值比较,A组缺血期及再灌注期 LVEDP升高,CO、SV、LVEF、CPP、RPP降低,再灌注期MAP降低,HR减慢,B、C组上述缺血再灌注诱导的血液动力学变化减弱,A组缺血期及再灌注期RWMS增加,但B、C组缺血期RWMS低于A组(P< 0.05或0.01)。结论异丙酚预处理对犬心肌缺血再灌注损伤有一定的保护作用,腺苷预处理并未增强其保护作用。  相似文献   
22.
23.
The objective of this study is to assess the efficacy and safety of herbal medicines (HMs), as a monotherapy or adjunct therapy, compared to placebo or conventional approaches in the treatment of idiopathic Parkinson's disease (PD). We conducted a systematic review of randomized controlled trials from both conventional and alternative medicine sources. Outcome measures were overall improvement, quality of life, reduction of levodopa dose, and adverse events. Nine studies were included, each testing a different HM. Six of the trials had limited internal validity due to major flaws in design, including the lack of proper randomization; insufficient blinding; unclear inclusive criteria in terms of diagnostic criteria, baseline staging, and duration of disease; lack of proper sample size calculation; and insufficient data analysis. Imbalances in gender and ethnicity among the patients in the included trials were observed. No major adverse events emerged, and no specific pattern was detected from the trials describing such data. In addition to major methodological defects, heterogeneity in (1) HM tested, (2) control treatment, and (3) outcome measure hindered in-depth data analysis and synthesis. Current evidence is insufficient to evaluate the efficacy and safety of various HMs. Further studies with improved trial design and reporting, with assessment on cost-effectiveness, quality of life, and qualitative data are warranted.  相似文献   
24.
旋毛虫病在东南欧的巴尔干半岛及临近国家的流行现状各不相同,在保加利亚、塞尔维亚和黑山、罗马尼亚及克罗地亚,猪和人的旋毛虫感染率均较高;在波斯尼亚和黑塞哥维那则具有中度的旋毛虫感染率;在匈牙利已有多年未发现人体旋毛虫病,但近2年来已发现了散发的猪旋毛虫病。旋毛虫病在东南欧国家的再度肆虐,提示旋毛虫病能够突破食品安全体系和兽医检疫的薄弱环节,从而可导致地区性、全国性甚至国际性的旋毛虫病扩散。该文对旋毛虫病在东南欧国家的历史、分布、流行现状、感染来源、虫种及再度肆虐的原因等进行了综述。  相似文献   
25.
26.
Abstract: Background: Identification of risk drinking in expectant fathers may be helpful as an important part of efforts to minimize maternal alcohol use, and as an opportunity to inform them about a problematic practice during a critical developmental stage for the couple. The purpose of this study was to evaluate the T‐ACE screening questionnaire, which asks about t olerance to alcohol, being a nnoyed by other's comments about drinking, attempts to c ut down, and having a drink first thing in the morning (“ e ye‐opener”), in the male partners of pregnant women who themselves were T‐ACE positive. Methods: Two hundred fifty‐four male partners were asked to complete the T‐ACE embedded in a health survey, the Alcohol Use Disorders Identification Test (AUDIT), and other questions about their alcohol use in the past 30 days when their pregnant partners had a median gestation of 11.5 weeks (T1). After delivery, male partners again completed the T‐ACE and quantity‐frequency questions (T2). The predictive ability of the T‐ACE and AUDIT was compared, using risk drinking (>4 drinks/day or >14 drinks/week) as the criterion standard. Results: A substantial minority of male partners had risk drinking, 31 percent at T1 and 25 percent at T2. Although the AUDIT was better than the T‐ACE as an independent predictor of risk drinking, the latter was most accurate when the tolerance threshold exceeded 2 drinks, the same established for pregnant women. The sensitivity (T1 = 84.6%, T2 = 82.8%) and specificity (T1 = 43.8%, T2 = 51.1%) of the T‐ACE at this threshold compared favorably with those of the AUDIT at the standard cut point of 8. Conclusions: The T‐ACE may be a practical way for clinicians to identify risk drinking in both pregnant women and expectant fathers. (BIRTH 33:2 June 2006)  相似文献   
27.
28.
李强  张昱苹  谢东 《海南医学》2002,13(3):18-20
目的:探讨高分辨率CT(HRCT)对颞部疾病的检查价值。方法:对43例颞部疾病患者行常规CT和高分辨率CT(HRCT)检查所获图像对比分析,并讨论HRCT的检查技术和图像后处理。结果:HRCT对病变的显示率及病变引起骨质破坏的程度,病变边缘,轮廓的显示均明显优于常规CT,尤其能清楚显示常规CT难以显示的中耳及内耳的细微结构,结论:高分辨率CT是颞部疾病的首选检查方法,使用高分辨率CT对颞部疾病的检查给临床提供更多,更准确的诊断信息。  相似文献   
29.
OBJECTIVE: To understand the role of nasal mucous epithelial cells to hypoxia in early stage of nasal polyps(NP) formation. METHODS: Epithelial cells of NP and inferior turbinate (IT) were cultured without serum under normal oxygen and hypoxia, and stimulus of inflammatory cytokines. Erythropoietin (EPO) was regarded as hypoxia mark, and expression of vascular endothelial growth factor(VEGF) mRNA and protein derived from epithelial cells were detected respectively by in situ hybridization and ELISA. RESULTS: 1. Under hypoxia, EPO mRNA was expressed intensely in epithelial cells from NP and IT, and there was no significant difference between both of them. This result suggested that EPO might be regarded as a hypoxic mark. 2. The ability of producing VEGF mRNA increased with cytokines stimulation, especially under hypoxia. Protein level of VEGF from epithelial cells of NP and IT increased with cytokines stimulation, especially in hypoxia and was time-dependent. CONCLUSION: Epithelial cells actively produce vast VEGF under hypoxia. The VEGF induced by hypoxia of the mucosa in middle meatus is of importance in the formation of nasal polyps(NP) in early stage, which may be the major cause of NP formation in middle meatus.  相似文献   
30.
目的探讨儿童过敏性紫癜的影像学特点及其临床价值。方法回顾性分析32例过敏性紫癜并发肠套叠患儿的临床及影像学资料。结果出现并发症之前过敏性紫癜的腹部X线主要表现为局限性小肠充气扩张,粘膜增粗,肠间隙增宽,可伴有液平;B超显示为不同程度的多发节段性肠壁水肿增厚,肠管狭窄等表现;出现并发症后,其X线表现加重,部分病例伴有肠穿孔;B超及X线监视下空气灌肠可以明确是否并发肠套叠,部分病例可通过空气灌肠达到复位治疗的目的。结论影像学检查的重要临床价值在于能与需要手术治疗的其他急腹症相鉴别,同时可以了解其是否并发常见的并发症,为临床确定治疗方案提供可靠的信息。  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