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   4374篇
  免费   357篇
  国内免费   52篇
耳鼻咽喉   2篇
儿科学   1085篇
妇产科学   145篇
基础医学   531篇
口腔科学   62篇
临床医学   213篇
内科学   192篇
皮肤病学   41篇
神经病学   46篇
特种医学   62篇
外科学   129篇
综合类   462篇
预防医学   946篇
眼科学   4篇
药学   332篇
  4篇
中国医学   476篇
肿瘤学   51篇
  2023年   59篇
  2022年   109篇
  2021年   263篇
  2020年   185篇
  2019年   162篇
  2018年   151篇
  2017年   154篇
  2016年   178篇
  2015年   170篇
  2014年   268篇
  2013年   303篇
  2012年   180篇
  2011年   186篇
  2010年   192篇
  2009年   164篇
  2008年   146篇
  2007年   164篇
  2006年   131篇
  2005年   118篇
  2004年   128篇
  2003年   116篇
  2002年   95篇
  2001年   83篇
  2000年   75篇
  1999年   73篇
  1998年   50篇
  1997年   58篇
  1996年   58篇
  1995年   49篇
  1994年   78篇
  1993年   49篇
  1992年   47篇
  1991年   34篇
  1990年   38篇
  1989年   36篇
  1988年   39篇
  1987年   40篇
  1986年   44篇
  1985年   34篇
  1984年   44篇
  1983年   39篇
  1982年   58篇
  1981年   33篇
  1980年   20篇
  1979年   23篇
  1978年   17篇
  1977年   12篇
  1976年   8篇
  1975年   6篇
  1973年   4篇
排序方式: 共有4783条查询结果,搜索用时 15 毫秒
1.
2.
“母乳最好”的宣传话语在目前育龄人群中几乎耳熟能详,但很多信奉科学育儿、希望母乳喂养的都市女性却发现母乳喂养困难重重,其中遭遇“母乳不足”的案例较为多见。回顾历史发现,“母乳不足”的现象全球普遍存在,这个话题在20世纪80年代的英语学术圈曾引起热议。经过十余年讨论后,学者们基本认同大部分遭遇母乳不足的女性并不是真正的“母乳不足”,而是由于种种社会文化因素干扰造成母乳喂养失败的这一结论,其中产后初期的奶瓶介入是重要原因。术语也由insufficient milk syndrome变为perceived insufficient milk,以此来强调“母乳不足”不是一种病理现象,而更多是一种文化感知。  相似文献   
3.
目的:探讨益气养阴解毒方联合环磷腺苷葡胺注射液对病毒性心肌炎患者心功能及外周血清肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、转化生长因子-β1(transforming growth factor-β1,TGF-β1)和干扰素-γ(interferon-γ,IFN-γ)水平的影响。方法:将70例病毒性心肌炎患者按照随机数字法分为对照组和观察组,每组各35例。两组患者均给予常规治疗,对照组在常规治疗的基础上给予环磷腺苷葡胺注射液静脉滴注,观察组在对照组的基础上联合益气养阴解毒方治疗。比较两组患者的临床疗效及治疗前后左室短轴缩短分数(left ventricular shortening fraction,LVFS)、左心室射血分数(left ventricular ejection fraction,LVEF)、心脏指数(cardiac index,CI)、TNF-α、TGF-β1和IFN-γ水平。结果:观察组有效率为88.57%,对照组有效率为68.57%,两组患者有效率比较,差异有统计学意义(P<0.05)。两组患者治疗后LVEF、LVFS高于本组治疗前,且观察组高于对照组,差异具有统计学意义(P<0.05)。两组患者治疗后TGF-β1、TNF-α水平低于治疗前比较,IFN-γ高于治疗前,且观察组TGF-β1、TNF-α低于对照组,IFN-γ高于对照组,差异均有统计学意义(P<0.05)。两组患者不良反应发生率比较,差异无统计学意义(P>0.05)。结论:益气养阴解毒方联合环磷腺苷葡胺注射液治疗病毒性心肌炎疗效更显著,可减轻机体的炎症反应,恢复患者心功能。  相似文献   
4.
减少血糖波动是目前干预糖尿病和预防并发症的重点,也是中医药在糖尿病治疗中的优势所在。越来越多的研究表明,胰岛微循环障碍是胰岛功能下降进而引发血糖波动的关键病理环节,而胰岛微循环局部肾素-血管紧张素系统(renin-angiotensin system,RAS)的过度激活作为胰岛功能失代偿的使动环节,与胰岛内分泌细胞功能密切相关,是研究胰岛功能的关键靶点。中医学认为糖尿病血糖波动与"脾气散精"障碍密切相关,脾不散"精"(血糖),精滞为浊,浊邪壅塞,是血糖稳态失衡的使动环节,亦为糖尿病全病程的关键病机。通过补益"脾"气以促进"胰"中精微物质的布散能够恢复糖调节激素间的平衡,从而减少血糖波动。目前,"脾气散精"对血糖波动的调节机制尚不明确。作者基于以往的临床和科研工作基础,提出"脾气散精"环节通过促进机体胰岛微循环从而发挥其改善胰岛功能、调节血糖稳态的作用,其机制可能与抑制胰岛微循环局部RAS的激活状态相关。RAS系统在胰岛微循环中各信号通路的相互拮抗关系,与中医理论中脾气散精与固精作用的对立制约关系相类似。因此"脾气散精"环节对血糖波动的调节机制有必要从胰岛微循环RAS整体调控的角度进行深入探索,以此揭示中医药调节机体内环境稳态,减少糖尿病患者血糖波动的科学内涵。  相似文献   
5.
Necrotizing enterocolitis (NEC), a devastating infant disease characterized by severe intestinal necrosis, its pathogenesis is poorly understood, but appears to be multifactorial and highly associated with immaturity of gastrointestinal tract and immature innate-immune system. Breast-milk is effective strategy to protect infants against NEC. This study is using a NEC rat model to investigate the pathological mechanism of NEC involved intestinal-damages, and the therapeutic mechanism of sialylated human milk oligosaccharides (SHMOs) on NEC rats; also using cell model to investigate the effects of SHMOs on colon-epithelial cells (Caco-2) in-vitro.Extraction and characterization of SHMOs from breast milk, establishment of a NEC rat model, histopathological analysis and mast cell accounting of the terminal ileum were taken; The levels of DPPI, TLR4, IL-6, TNF-α, MMP-2/9 and glutathione were measured using various methods. Caco-2 cells were pre-treated with SHMOs and cultured with LPS, histamine, chymase or DPPI, cell viabilities and mitochondrial membrane potential were examined; flow cytometry was used to detect cell cycle.The accumulation of mast cells was found in the ileum of NEC rats, but prohibited by SHMOs treatment; the increased levels of TLR4, DPPI, IL-6, TNF-α, MMP-2/9 in NEC ileum were suppressed by SHMOs in-vivo. SHMOs prevented Caco-2 cells from LPS, histamine, chymase induced damages by surviving cell viability, regulating G0/G1 and S phase in cell cycles, and increasing mitochondrial membrane potential. These findings provide a new insight into the pharmacological mechanism of SHMOs treatment for NEC and suggest that SHMOs needs well attention for therapeutic aims.  相似文献   
6.
Milk remains one of the most frequently recommended solutions for storage of avulsed teeth because it can maintain cell viability and is easily accessible. However, some negative effects of milk on avulsed teeth have been reported, just as the effects of milk on the long‐term functions of cells are not clear. This study aimed to evaluate the effects of different types of milk on the viability, proliferation, and functions of periodontal ligament fibroblasts (PDLF)s in vitro. Human PDLFs were culture‐medium depleted for 5 min and stored in Hanks’ balanced salt solution (HBSS), whole cow's milk, low‐fat cow's milk, or almond milk for 1 h at 25°C. Cell viability and proliferation were assessed using MTT assays. Expression of the genes encoding type I collagen and its modifying enzymes were analyzed using real‐time PCR. Collagen matrix production was evaluated using Picrosirius red polarization. Our results showed the overall efficiency of low‐fat cow's milk in maintaining the viability and proliferation of PDLFs, and in enhancing the process of collagen production. Almond milk storage resulted in the highest rate of PDLF proliferation, and comparable collagen biosynthesis ability to the control. Therefore, besides low‐fat cow's milk, almond milk may potentially be an alternative tooth‐storage medium for PDLF preservation and PDL tissue regeneration.  相似文献   
7.
Objective: To assess the effect of electroacupuncture(EA) on expression of cytoskeletal proteins from Sertoli cells(SCs) and spermatogenesis in rats with oligozoospermia of insufficiency of Shen(Kidney)essence syndrome(OIKES).Methods: Twenty healthy male Sprague-Dawley rats were randomly assigned to four groups using a random number table: control,tripterygium glycosides(TG) treatment,sham and EA groups(n=5 in each group).A rat model of OIKES was established by oral gavage with TG.The EA group was treated with TG and received EA at Shenshu(BL 23) and Zusanli(ST 36) acupoints for 20 min,once daily for 30 days,while the sham group received EA at identical acupoints with skin penetration without stimulation.After 30 days,the ?nal body weight and coef?cients for the testis and epididymis were calculated and sperm parameters were measured.Immunohistochemical analyses were performed to detect expression of vimentin and α-tubulin in SCs and proliferating cell nuclear antigen(PCNA) immunoreactivity in germ cells.Apoptosis in germ cells was quanti?ed by the transferase biotin-dUTP nick end labeling assay.Results: Compared with the control group,the final body weight and testis/epididymis coefficients of rats in the TG-treated group were not significantly different,but the sperm count and motility were lower(P0.05).Expressions of vimentin and α-tubulin were also signi?cantly weaker(P0.01).The PCNA immunoreactivity of germ cells was decreased(P=0.059),whereas the apoptotic index of germ cells was increased signi?cantly(P0.01).In contrast,EA at BL 23 and ST 36 acupoints signi?cantly improved the ?nal body weight as well as the sperm count,concentration and motility(P0.01 or P0.05).EA increased expression of vimentin and α-tubulin in SCs markedly,and signi?cantly enhanced PCNA immunoreactivity with decreased apoptosis in germ cells(P0.01 or P0.05).Conclusions: EA at BL 23 and ST 36 acupoints has protective effects on spermatogenesis in rats with OIKES.This effect seems to be achieved by attenuating TG-induced disruption of cytoskeletal protein in SCs.  相似文献   
8.
9.
本文旨在探讨影响新疆低温乳消费市场的限制性因素及相应的对策。调研通过网络调查问卷和实地调研走访相结合的方式,从乳制品消费结构、消费能力,低温奶认知、低温奶购买意愿、购买便利性、购买偏好及健康饮奶习惯等方面分析影响新疆低温乳消费市场的因素。结果显示:32.93%的消费者不了解乳中生物活性物质(如乳铁蛋白)的热敏性,39.97%的消费者不能区分各类液态乳产品,47.64%的消费者有煮沸巴氏杀菌乳后饮用的习惯;43.21%的消费者"担心未消毒彻底,存在细菌",36.30%的消费者认为"加热后可增加营养价值和香味";72.64%的消费者曾感到"购买巴氏杀菌乳不方便";54.85%的消费者认为本地品牌"更新鲜、更健康"。结果启示:本地乳企应该充分利用在当地的良好品牌信誉度和牧场资源,尽早布局低温奶市场,通过研发高品质低温乳制品、普及科学饮奶理念、改善冷链物流能力、完善购物体验和精细化服务能力等手段,提高生产竞争力,抵御进口乳制品和常温乳对当地乳品市场的冲击,占领区域低温奶消费市场。  相似文献   
10.
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