首页 | 官方网站   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   15713篇
  免费   739篇
  国内免费   375篇
医药卫生   16827篇
  2023年   202篇
  2022年   317篇
  2021年   558篇
  2020年   634篇
  2019年   453篇
  2018年   388篇
  2017年   624篇
  2016年   640篇
  2015年   575篇
  2014年   1388篇
  2013年   2123篇
  2012年   1779篇
  2011年   1571篇
  2010年   1150篇
  2009年   940篇
  2008年   789篇
  2007年   410篇
  2006年   362篇
  2005年   336篇
  2004年   268篇
  2003年   179篇
  2002年   132篇
  2001年   54篇
  2000年   37篇
  1999年   26篇
  1998年   46篇
  1997年   39篇
  1996年   36篇
  1995年   28篇
  1994年   15篇
  1993年   14篇
  1992年   9篇
  1990年   17篇
  1989年   11篇
  1988年   15篇
  1987年   13篇
  1986年   8篇
  1985年   64篇
  1984年   77篇
  1983年   87篇
  1982年   85篇
  1981年   55篇
  1980年   58篇
  1979年   42篇
  1978年   36篇
  1977年   28篇
  1976年   23篇
  1975年   24篇
  1974年   20篇
  1973年   24篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
Synergism between Mycobacterium tuberculosis (M. tuberculosis) and HIV-1 infections was demonstrated in several in vitro models and clinical studies. Here, we investigated their reciprocal effects on growth in chronically HIV-1-infected promonocytic U1 cells and in acutely infected monocyte-derived macrophages (MDM). Phagocytosis of M. tuberculosis induced HIV-1 expression in U1 cells, together with increased TNF-alpha production. M. tuberculosis growth, evaluated by competitive PCR, was greater in HIV-1-infected MDM compared to uninfected cells. M. tuberculosis phagocytosis induced greater TNF-alpha and IL-10 production in HIV-1-infected MDM than in uninfected cells. In uninfected MDM, addition of TNF-alpha and IFN-gamma decreased, whereas IL-10 increased M. tuberculosis growth. On the contrary, in HIV-1-infected MDM, addition of TNF-alpha and IFN-gamma increased, whereas IL-10 has no effect on M. tuberculosis growth. TNF-alpha seems to play a pivotal role in the enhanced M. tuberculosis growth observed in HIV-1-infected MDM, being unable to exert its physiological antimycobacterial activity. Here, for the first time we demonstrated an enhanced M. tuberculosis growth in HIV-1-infected MDM, in line with the observed clinical synergism between the two infections.  相似文献   
52.
目的:研究针刺对多囊卵巢综合征(PCOS)大鼠卵巢转化生长因子α(TGF-α)、表皮生长因子受体(EGFR)表达的影响,探讨针刺促排卵的作用机制。方法:24日龄雌性大鼠颈背部皮下注射脱氢表雄酮(DHEA)的油溶液制作(PCOS)模型,对照组同期皮下注射油剂。PCOS大鼠随机分为模型组和针刺组。模型组不作处理,针刺组大鼠从80日龄起针刺关元、中极、双侧三阴交、双侧子宫穴,1次/天,15min/次,连续6周。治疗结束后各组大鼠断头处死,迅速取血并分离血清,-20℃冰箱保存,待测性激素水平。摘取双侧卵巢,称重,4%多聚甲醛固定,作HE染色和免疫组织化学染色。结果:与模型组相比,针刺组卵巢湿重、卵巢TGF-α、EGFR表达及血清睾酮(T)、雌二醇(E2)水平均显著降低(P<0.01),而卵泡刺激素(FSH)、黄体生成素(LH)、孕酮(P4)水平差异无统计学意义(P>0.05)。结论:针刺能显著降低PCOS大鼠卵巢TGF-α及EGFR的表达,抑制TGF-α对卵巢和激素合成的作用,改善PCOS大鼠多囊样变和高雄激素血症,促进排卵。  相似文献   
53.
Alpha-methylacyl CoA racemase (AMACR), also known as P504S, plays an important role in peroxisomal beta-oxidation of branched-chain fatty acids. It has recently been shown that AMACR is highly expressed in prostate cancer and that it may be an important diagnostic marker for prostate carcinoma. However, little is known about expression of AMACR in normal tissues and other malignant tumors. In this study, we investigated expression of AMACR in 539 malignant tumors and 222 normal human tissues of various types by immunohistochemical analysis. mRNA levels of AMACR in normal organs and in selected tumors were assessed by real time PCR. In normal tissue, high expression of AMACR mRNA was identified in liver, kidney and salivary gland, while AMACR protein was detected in liver (hepatocytes), kidney (tubular epithelial cells), lung (only bronchial epithelial cells), and gallbladder (only mucosal epithelial cells). High expression of AMACR mRNA was found in prostate, liver, and kidney cancers but rarely in stomach and bladder cancers. A high percent of adenocarcinomas arising from these organs express AMACR, including 17 of 21 (81%) of hepatocellular carcinomas and 18 of 24 (75%) of renal cell carcinomas. In addition, carcinomas arising from tissues normally not expressing AMACR were also positive for the antigen, including 17 of 18 (94%) prostate carcinomas, 9 of 29 (31%) of urothelial carcinomas, and 4 of 15 (27%) of gastric adenocarcinomas. Two hundred and fifty cases of adenocarcinomas from lung, breast, pancreas, bile duct, adrenal gland, salivary gland, ovary, thyroid and endometrium were negative or rarely positive for AMACR. Neuroendocrine carcinomas rarely expressed AMACR. Melanomas, squamous cell carcinomas, basal cell carcinomas, soft tissue tumors (including epithelioid sarcomas and synovial sarcoma), thymomas, and germ cell tumors were negative for AMACR. Our data provide important baseline information for using AMACR in clinical practice and also are valuable in furthering understanding of the pathogenic role of AMACR in malignant neoplasms.  相似文献   
54.
Juvenile dermatomyositis (JDM) is the most common pediatric inflammatory myopathy. In patients with JDM, the A --> G polymorphism in the tumor necrosis factor alpha (TNFalpha)-308 promoter region (TNFalpha-308A) is associated with prolonged disease course and increased production of TNFalpha by peripheral blood mononuclear cells (Arthritis Rheum. 43, 2368-2377, 2000). Magnetic resonance imaging directed biopsies from 21 white children with untreated JDM were evaluated for TNFalpha expression. Using monoclonal antibody to TNFalpha, fresh frozen sections were processed by the standard immunohistochemical technique. We investigated the association among the expression of TNFalpha by muscle fibers, disease activity, duration of untreated disease, and the TNFalpha-308 polymorphism. Untreated children with JDM who had the TNFalpha-308A allele had an increased number of TNFalpha stained muscle fibers than children with the TNFalpha-308G allele (P = 0.001). There was no association with disease activity or duration of untreated disease. We speculate that muscle fiber production of TNFalpha provides a microenvironment in which TNFalpha acts synergistically with other mediators to prolong muscle fiber damage.  相似文献   
55.
56.
 目的 系统评价与分析恩替卡韦(ETV)序贯聚乙二醇化干扰素-α(Peg-IFN-α)与单用ETV在治疗慢性乙型肝炎患者中的临床疗效。方法 计算机检索PubMed、Embase、Cochrane Library、中国知网、万方数据库,搜索有关ETV及ETV序贯Peg-IFN-α治疗慢性乙型肝炎的随机对照试验研究,应用Stata 16.0软件对符合纳入条件的临床研究进行系统评价与分析。结果 共纳入10篇文献,1 250例患者,其中553例患者采用ETV序贯Peg-IFN-α治疗,697例患者单用ETV治疗,两组患者组间基线特征比较,差异均无统计学意义(均P>0.05)。ETV序贯Peg-IFN-α试验组的HBsAg转换率、HBsAg清除率、HBeAg转换率、HBeAg清除率均高于ETV对照组,差异均有统计学意义(均P<0.05)。结论 在慢性乙型肝炎抗病毒治疗中,总体上ETV序贯Peg-IFN-α治疗疗效优于单用ETV。  相似文献   
57.
目的观察重组人干扰素α2b雾化吸入联合远红外止咳贴治疗毛细支气管炎的效果。方法选取2018年3月至2020年3月玉林市妇幼保健院收治的80例毛细支气管炎患儿,采用随机数字表法分为观察组与对照组,每组各40例。对照组给予常规综合治疗,观察组在常规综合治疗的基础上给予氧气驱动雾化吸入α2b干扰素联合远红外止咳贴治疗。比较两组治疗后的临床疗效、临床症状消失时间、住院时间以及肺部功能。结果观察组临床总有效率高于对照组,差异有统计学意义(P<0.05);观察组喘憋消失时间、咳嗽消失时间、肺部啰音消失时间、体温恢复正常时间、住院时间均短于对照组,差异有统计学意义(P<0.05);观察组治疗后潮气量、达峰时间比、达峰容积比均高于对照组,差异有统计学意义(P<0.05)。结论雾化吸入干扰素α2b联合远红外止咳贴治疗毛细支气管炎对提高治疗有效率,缩短临床症状消失时间、住院时间,改善肺功能具有重要作用,值得临床推广使用。  相似文献   
58.
Objective: To establish a method for directional screening of the cytotoxic components from the medicinal herb of Achnatherum inebrians by a combination of surface plasmon resonance (SPR) biosensor and chromatographic isolation technology. Methods: Under the guidance of bioactive assessment based on binding abilities between objects and the α-Mannosidase (α-Man) target, the active components from different solvents extracts, different polar extraction parts and fractions were screened orderly and directionally using SPR. Components with a high binding ability to α-Man can be precisely oriented in a narrower fractions range and are easy to isolate. Three human cancer cells were used to evaluate the cytotoxic activity of component with the highest affinity to α-Man. Results: Eight compounds were isolated and identificated from A. inebrians for the first time. Deoxyvasicinone possessed the highest affinity to α-Man among them. Moreover, deoxyvasicinone showed good effects on inhibited proliferation of human hepatoma cells HepG2 (IC50 = 5.7 μmol/L), human breast cancer cells MCF7 (IC50 = 7.21 μmol/L) and human lung cancer cells HCC827 (IC50 = 0.75 μmol/L), respectively. In particular, its inhibitory effect on HCC827 was stronger than the positive drug gefitinib (IC50 = 1.65 μmol/L). Conclusion: A comprehensive strategy of directional screening potential cytotoxic components from herb based on biomolecular interaction and chromatography was established. Deoxyvasicinone as an effective anti-cancer component was initially isolated from A. inebrians. It is expected that this screening strategy could provide new perspectives for rapid screening and identification of active components from natural plants with the complex matrix.  相似文献   
59.
目的:探讨降糖方对糖耐量异常大鼠糖脂代谢及骨骼肌组织κB抑制蛋白α(IκB-α)、核转录因子肽p65(NF-κBp65)的影响。方法:SD大鼠随机分为正常组、模型组、盐酸二甲双胍组、降糖方低、高剂量组,采用高脂饮食喂养4周,链脲佐菌素(STZ)腹膜内注射建立糖耐量异常大鼠模型,治疗8周后,观察骨骼肌组织病理变化,测定空腹血糖(FPG)、血清胰岛素(FINS)、胰岛素抵抗指数(HOMA-IR)、甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-C)、骨骼肌组织IκB-α mRNA、NF-κBp65 mRNA水平、骨骼肌组织白细胞介素-4(IL-4)、白细胞介素-12(IL-12)、肿瘤坏死因子-α(TNF-α)蛋白水平。结果:正常组大鼠骨骼肌组织结构正常,模型组骨骼肌排列紊乱、肌纤维断裂、可见明显炎症细胞浸润;盐酸二甲双胍及降糖方干预后,骨骼肌炎症细胞浸润减少,肌纤维排列趋于整齐。模型组大鼠FPG、FINS、HOMA-IR水平、血清TG、TC、LDL-C水平、骨骼肌IκB-α mRNA、NF-κBp65 mRNA和蛋白水平、骨骼肌组织IL-4、IL-12、TNF-α蛋白水平高于对...  相似文献   
60.
目的:探讨当归通痹汤联合中药热敷治疗膝关节骨性关节炎的疗效及对白细胞介素(IL)-1β、基质金属酶(MMP)-3和肿瘤坏死因子(TNF)-α水平的影响。方法:选取我院收治的膝关节骨性关节炎患者140例,随机分为两组各70例。对照组给予中药热敷治疗,治疗组在对照组基础上给予当归通痹汤,对比两组治疗后的临床疗效、VAS评分、WOMAC指数和ADL评分,以及IL-1β、MMP-3和TNF-α水平。结果:治疗后,治疗组的总有效率为94.29%,高于对照组的81.43%,差异有统计学意义(P<0.05);两组ADL评分明显升高,WOMAC指数、VAS评分明显降低(P<0.05);且治疗组比对照组明显改善(P<0.05);两组患者治疗后的IL-1β、MMP-3和TNF-α水平均显著低于治疗前(P<0.05);且治疗组低于对照组,差异有统计学意义(P<0.05)。两组患者不良反应发生率差异无统计学意义(P>0.05)。结论:膝关节骨性关节炎患者采用当归通痹汤联合中药热敷治疗,具有较好的临床疗效,能够改善患者膝关节功能,值得在临床上推广应用。  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-23

京公网安备 11010802026262号