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   213403篇
  免费   20794篇
  国内免费   14606篇
耳鼻咽喉   2094篇
儿科学   2826篇
妇产科学   1862篇
基础医学   20085篇
口腔科学   3715篇
临床医学   26848篇
内科学   27208篇
皮肤病学   2376篇
神经病学   8589篇
特种医学   7604篇
外国民族医学   89篇
外科学   21012篇
综合类   46201篇
现状与发展   64篇
一般理论   13篇
预防医学   18110篇
眼科学   4852篇
药学   23014篇
  237篇
中国医学   16213篇
肿瘤学   15791篇
  2024年   807篇
  2023年   3020篇
  2022年   7715篇
  2021年   9980篇
  2020年   7983篇
  2019年   6028篇
  2018年   6592篇
  2017年   6758篇
  2016年   6257篇
  2015年   9891篇
  2014年   12227篇
  2013年   12549篇
  2012年   18154篇
  2011年   19411篇
  2010年   14483篇
  2009年   12148篇
  2008年   13749篇
  2007年   13436篇
  2006年   12571篇
  2005年   10696篇
  2004年   7894篇
  2003年   7604篇
  2002年   6311篇
  2001年   4942篇
  2000年   3771篇
  1999年   2999篇
  1998年   1701篇
  1997年   1660篇
  1996年   1286篇
  1995年   1124篇
  1994年   932篇
  1993年   582篇
  1992年   600篇
  1991年   529篇
  1990年   461篇
  1989年   352篇
  1988年   305篇
  1987年   295篇
  1986年   220篇
  1985年   162篇
  1984年   87篇
  1983年   69篇
  1982年   47篇
  1981年   56篇
  1980年   31篇
  1979年   57篇
  1978年   21篇
  1977年   25篇
  1974年   28篇
  1973年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
本研究拟探讨染料木黄酮对前列腺癌细胞LNCaP和CWR22RV1的增殖、迁移和侵袭能力的影响。一、材料与方法1.材料:前列腺癌细胞株LNCaP和CWR22RV1(中国科学院上海生命科学研究院);Genistein(天津科瑞泰科技有限公司);RPMI 1640、胎牛血清(FBS)、胰蛋白酶(美国Gibco公司);E-钙黏蛋白(E-cadherin)、N-钙黏蛋白(N-cadherin)、波形蛋白(Vimentin,Abcam公司);聚氰基丙烯酸正丁酯(BCA)试剂盒、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)上样缓冲液(×5)及蛋白质印迹法(Western blot)试剂盒(上海市碧云天生物公司);2.实验方法:采用噻唑蓝(MTT)实验、划痕实验和Transwell实验检测Genistein对细胞增殖、迁移及侵袭能力的影响。采用Western blot检测E-cadherin、N-cadherin、Vimentin、CD44和Oct-4的表达水平。  相似文献   
33.
Abstract

Background

Comorbidities are commonly seen in patients with coronavirus disease 2019 (COVID-19), but the clinical implication is not yet well-delineated. We aim to characterize the prevalence and clinical implications of comorbidities in patients with COVID-19.  相似文献   
34.
Mammalian spermatogenesis is a well-organized process of cell development and differentiation. Meiosis expressed gene 1 (MEIG1) plays an essential role in the regulation of spermiogenesis. To explore potential mechanisms of MEIG1''s action, a yeast two-hybrid screen was conducted, and several potential binding partners were identified; one of them was membrane occupation and recognition nexus repeat containing 3 (MORN3). MORN3 mRNA is only abundant in mouse testis. In the testis, Morn3 mRNA is highly expressed in the spermiogenesis stage. Specific anti-MORN3 polyclonal antibody was generated against N-terminus of the full-length MORN3 protein, and MORN3 expression and localization was examined in vitro and in vivo. In transfected Chinese hamster ovary cells, the antibody specifically crossed-reacted the full-length MORN3 protein, and immunofluorescence staining revealed that MORN3 was localized throughout the cytoplasm. Among multiple mouse tissues, about 25 kDa protein, was identified only in the testis. The protein was highly expressed after day 20 of birth. Immunofluorescence staining on mixed testicular cells isolated from adult wild-type mice demonstrated that MORN3 was expressed in the acrosome in germ cells throughout spermiogenesis. The protein was also present in the manchette of elongating spermatids. The total MORN3 expression and acrosome localization were not changed in the Meig 1-deficient mice. However, its expression in manchette was dramatically reduced in the mutant mice. Our studies suggest that MORN3 is another regulator for spermatogenesis, probably together with MEIG1.  相似文献   
35.
丁伟  王邦宁 《安徽医药》2016,37(2):167-170
目的 探讨非高密度脂蛋白胆固醇水平(non-HDL-C)与冠心病(CHD)患者冠状动脉病变Gensini评分的关系及临床意义。方法 对225例疑诊或既往临床诊断CHD患者予以冠状动脉造影(CAG),将造影阴性的39例作为对照组(HC组),造影阳性的186例患者诊断为CHD,结合临床特点分为心绞痛组(AP组)122例和心肌梗死组(AMI组)64例。采用Gensini评分对冠状动脉病变程度评分,测定患者全套血脂水平,探讨non-HDL-C及相关脂质成分与冠状动脉病变程度Gensini评分的相关性;同时对他汀类药物强化降脂达标,低密度脂蛋白胆固醇(LDL-C)<1.80 mmol/L的AP组患者进行non-HDL-C与冠状动脉病变程度Gensini评分的亚组分析。结果 AMI组non-HDL-C水平高于AP组及HC组,AP组non-HDL-C水平高于HC组,差异均有统计学意义(P<0.05);CHD患者non-HDL-C水平与Gensini评分呈正相关(r=0.562,P<0.05);LDL-C控制达标的AP组患者,高non-HDL-C组(≥2.60 mmol/L)比低non-HDL-C组(<2.60 mmol/L)Gensini评分明显升高,差异均有统计学意义(P<0.05)。结论 non-HDL-C与冠状动脉病变程度密切相关,non-HDL-C在评估LDL-C控制达标患者的冠状动脉病变程度及再发心血管事件风险上有一定价值,可作为LDL-C达标后心血管残余风险新的观察指标。  相似文献   
36.
Melatonin induces apoptosis in many different cancer cell lines, including colorectal cancer. However, the precise mechanisms involved remain largely unresolved. In this study, we provide evidence to reveal a new mechanism by which melatonin induces apoptosis of colorectal cancer LoVo cells. Melatonin at pharmacological concentrations significantly suppressed cell proliferation and induced apoptosis in a dose‐dependent manner. The observed apoptosis was accompanied by the melatonin‐induced dephosphorylation and nuclear import of histone deacetylase 4 (HDAC4). Pretreatment with a HDAC4‐specific siRNA effectively attenuated the melatonin‐induced apoptosis, indicating that nuclear localization of HDAC4 is required for melatonin‐induced apoptosis. Moreover, constitutively active Ca2+/calmodulin‐dependent protein kinase II alpha (CaMKIIα) abrogated the melatonin‐induced HDAC4 nuclear import and apoptosis of LoVo cells. Furthermore, melatonin decreased H3 acetylation on bcl‐2 promoter, leading to a reduction of bcl‐2 expression, whereas constitutively active CaMKIIα(T286D) or HDAC4‐specific siRNA abrogated the effect of melatonin. In conclusion, the present study provides evidence that melatonin‐induced apoptosis in colorectal cancer LoVo cells largely depends on the nuclear import of HDAC4 and subsequent H3 deacetylation via the inactivation of CaMKIIα.  相似文献   
37.
蒋巍  孙育民  李颖  王蓓  薛元媛  王骏 《心脏杂志》2015,27(2):249-250
1临床资料患者,男,43岁,因"四肢近端肌肉无力9个月,加剧1周"于2013年9月22日入院。患者于9个月前无明显诱因下出现四肢肌肉无力,以近端肌力减退为主,主要表现为上楼梯费力,提重物困难,易疲劳,尚可参加工作,无发热、皮疹、肌痛、感觉异常等,无明显晨轻暮重的波动现象,上述症状逐渐加重,劳动耐量和日常生活能力进行性下  相似文献   
38.
39.
In order to solve the problem of long-term (>9 months) efficacy in the treatment of Alzheimer''s disease (AD) by conventional therapy (CT), a staged and multiply-targeted sequential therapy based on the evolvement of patterns (STEP) was developed. Its main innovations include: (1) the time order of evolution of patterns defined by Chinese medicine (CM) in AD was found, that is, "the orderly pattern evolution starting from Shen (Kidney) deficiency, progressing to phlegm, stasis and fire, and worsening to severe toxin as well as functional collapse"; (2) the cascade hypothesis of Shen deficiency in AD and its sequential therapy based on Shen-reinforcing was proposed, that is, "reinforcing Shen in the early stage and throughout the whole process, resolving phlegm, activating blood and purging fire in the middle stage, detoxifying and replenishing vitality to stop the collapse in the advanced stage", and through meta-analysis, clinical drug use was optimized, thus the leap from "inferential selection" to "evidence-based selection" was realized; (3) the STEP regimen combined with CT maintained cognitive and behavioral stability in AD patients for at least 12 months, with cognitive enhancement and behavioral synergy after 9 months, and cognitive benefit was superior to CT at 9, 12, 15, 18, 21, and 24 months, respectively. The 2-year cognitive improvement rate was increased by 25.64% (P=0.020) and the cognitive deterioration rate was decreased by 48.71% (P=0.000). Among them, the cognitive and functional benefits of Shen-reinforcing therapy for very early AD (350 cases) for 1 year were better than the placebo (P<0.001), and the dementia conversion rate was reduced by 8.85% (P=0.002). The behavioral symptomatic relief of patients with vascular dementia received fire-purging therapy (540 cases) was superior to those received CT (P=0.016). These data suggested that the STEP regimen has synergistic effects on CTs at least in terms of cognitive benefit, and the earlier the use, the greater the benefit will have. Therefore, the STEP regimen should be considered as one of the clinical options, particularly for the dearth of effective pharmaceutical or immunological interventions that are currently available for AD.  相似文献   
40.
目的 探讨改良单图像法手工测量髌骨不稳患者胫骨结节-股骨滑车沟(tibial tuberosity-trochlear groove,TT-TG)间距的可行性。 方法 选取髌骨不稳患者30例。高年资手术医师A、B,使用改良单图像法手工测量髌骨不稳患者TT-TG间距,对比高资年影像学医师C,使用双图法测量髌骨不稳患者TT-TG间距。应用Cronbach′s alpha系数评价结果的可信度。应用组内相关系数(intraclass correlation coefficient,ICC)评价结果的可重复性。使用Bland-Altman分析图评价结果的一致性。 结果 高年资手术医师A、B使用改良单图像法手工测量髌骨不稳患者TT-TG间距分别和高年资影像学医师C使用双图法测量髌骨不稳患者TT-TG间距比较,Cronbach′s alpha系数分别为0.913和0.959,组内相关系数分别为0.913和0.958。Bland-Altman分析图显示,TT-TG间距差值(mm)的均值为-0.276(95%CI:-3.526~2.974)和0.143(95%CI:-3.110~3.397)。A、B医师之间使用改良单图像法手工测量髌骨不稳患者TT-TG间距比较,Cronbach′s alpha系数为0.891,组内相关系数为0.891。Bland-Altman分析图显示TT-TG间距差值(mm)的均值为-0.276(95%CI:-3.526~2.974)。 结论 改良单图像法手工测量髌骨不稳患者TT-TG间距操作简单,可以准确测量出髌骨不稳患者的TT-TG间距,该方法和双图法可以相互替换使用。  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