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   14126篇
  免费   1054篇
  国内免费   377篇
耳鼻咽喉   70篇
儿科学   287篇
妇产科学   216篇
基础医学   2938篇
口腔科学   230篇
临床医学   859篇
内科学   2211篇
皮肤病学   347篇
神经病学   823篇
特种医学   188篇
外科学   2008篇
综合类   1638篇
现状与发展   1篇
预防医学   923篇
眼科学   145篇
药学   1430篇
  3篇
中国医学   385篇
肿瘤学   855篇
  2023年   182篇
  2022年   249篇
  2021年   482篇
  2020年   395篇
  2019年   662篇
  2018年   523篇
  2017年   480篇
  2016年   437篇
  2015年   500篇
  2014年   827篇
  2013年   862篇
  2012年   708篇
  2011年   972篇
  2010年   770篇
  2009年   804篇
  2008年   671篇
  2007年   762篇
  2006年   745篇
  2005年   599篇
  2004年   548篇
  2003年   454篇
  2002年   329篇
  2001年   233篇
  2000年   220篇
  1999年   168篇
  1998年   135篇
  1997年   108篇
  1996年   116篇
  1995年   92篇
  1994年   70篇
  1993年   46篇
  1992年   38篇
  1991年   33篇
  1990年   24篇
  1989年   18篇
  1988年   19篇
  1987年   20篇
  1985年   123篇
  1984年   169篇
  1983年   131篇
  1982年   164篇
  1981年   134篇
  1980年   104篇
  1979年   115篇
  1978年   70篇
  1977年   53篇
  1976年   45篇
  1975年   53篇
  1974年   29篇
  1973年   35篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
OBJECTIVES: For the histological diagnosis of small lung cancers of 10 mm or less in diameter (< or =10), resection by video-assisted thoracic surgery (VATS) with computed tomography (CT)-guided marking is feasible. One problem is that a small number of these pulmonary nodules are malignant. We retrospectively analyzed CT images of pulmonary nodules to find better criteria to select candidates for resection among patients with small pulmonary nodules. METHODS: Ninety-four patients with indeterminate peripheral pulmonary nodules underwent wedge resection by VATS. High-resolution CT using a 1.25 mm slice included the area of lesions. Nodules were classified by size (< or =10, 11 to 20, >20 mm) and whether they had a ground-glass opacity (GGO) component. RESULTS: The histology of all 94 nodules showed 52 primary lung cancers, 6 metastatic tumors, 5 benign tumors, 8 intrapulmonary lymph nodes, and 23 inflammatory nodules. Ninety-three percent of nodules larger than 20 mm, 75% of nodules 10 to 20 mm, and 43% of nodules < or =10 mm were malignant. Introducing a classification according to GGO component to nodules, malignancy was detected in 88% of nodules with a GGO component and in 30% of nodules without a GGO component among nodules < or =10 mm. Nodules < or =10 mm with a GGO component showed a statistically significant (p < 0.01) correlation with malignancy. CONCLUSIONS: Pulmonary nodules < or =10 mm with GGO should be considered to have a high possibility of malignancy and to be candidates for resection by VATS.  相似文献   
52.
Altered dimerization of metabotropic glutamate receptor 3 in schizophrenia.   总被引:1,自引:0,他引:1  
BACKGROUND: Metabotropic glutamate receptors (mGlus) may be involved in the pathophysiology of schizophrenia. Group II mGlus (mGlu2 and mGlu3) have attracted considerable interest since the development of potent specific agonists that exhibit atypical antipsychotic-like activity and reports of a genetic association between the mGlu3 gene and schizophrenia. METHODS: In this postmortem study, mGlu3 protein levels in Brodmann area 10 of prefrontal cortex from schizophrenic (n = 20) and control (n = 35) subjects were analyzed by western immunoblotting using a novel specific mGlu3 antibody and an antibody for the vesicular glutamate transporter 1 (VGluT1). RESULTS: We report a significant decrease in the dimeric/oligomeric forms of mGlu3 in schizophrenic patients compared with control subjects, whereas total mGlu3 and VGluT1 levels were not altered significantly. CONCLUSIONS: This is the first experimental evidence that mGlu3 receptor levels are altered in schizophrenia and supports the hypothesis that neurotransmission involving this particular excitatory amino acid receptor is impaired in schizophrenia.  相似文献   
53.
目的:探讨连续性血液透析滤过(CVVHDF)后多器官功能障碍综合征(MODS)犬肝、肾组织白细胞介素-6(IL-6)和白细胞介素-10(IL-10)mRNA表达水平的变化及意义。方法:15只雄性Beagle犬,采用失血性休克+复苏灌注+内毒素血症复制MODS模型,随机分为CVVHDF组(n=8)和MODS组(n=7),CVVHDF组在内毒素注射完毕后给予CVVHDF治疗12h,MODS组不给CVVHDF治疗。测定各器官功能相关指标,同时应用半定量逆转录-聚合酶链反应(RT-PCR)测定两组肝、肾组织中IL-6、IL-10mRNA表达水平。结果:CVVHDF组治疗后肝、肾功能有关指标水平均有不同程度的改善;与MODS组相比,在内毒素注射后3h及以后各时间点,血清肌酐(Scr)、尿素氮(BUN)水平显著降低(P〈0.05);器官衰竭发生率较MODS组明显降低(37.5%vs85.7%,P〈0.05);MODS组肝、肾组织IL-6mRNA表达水平显著高于正常对照组和CVVHDF组(P〈0.01),而CVVHDF组肝、肾组织IL-10 mRNA表达水平显著高于正常对照组和MODS组(P〈0.01)。结论:连续性血液透析滤过能明显改善肾功能,CVVHDF早期应用可以降低MODS肝、肾组织IL-6/IL-10mRNA比值,有助于重建机体免疫系统内稳状态。  相似文献   
54.
CXCL10 (interferon- γ -inducible protein-10) levels are increased in cerebrospinal fluid of multiple sclerosis (MS) patients with symptomatic attacks of inflammatory demyelination, supporting a role for this molecule in MS pathogenesis. Two hundred and twenty-six patients with MS and 235 controls were genotyped for G  →  C and T  →  C single nucleotide polymorphisms (SNPs) in exon 4 of CXCL10 gene. Haplotypes were tested for association and correlated with clinical variables. The two SNPs studied were in complete linkage disequilibrium. None of the determined haplotypes was associated with MS. However, carriers of the GGTT haplotype (defined as wild type, according to the sequence in National Centre for Biotechnology Information (NCBI) database) had a significantly lower progression index than non-carriers ( P  = 0.016). Furthermore, amongst patients who had an initial relapsing remitting (RR) course of the disease, the time between onset and second episode was significantly longer in GGTT carriers ( P  = 0.021). Considering secondary progressive (SP)–MS patients, the time between the initial RR form and the subsequent worsening to SP was longer in this group ( P  = 0.08). Therefore, the GGTT haplotype of the CXCL10 gene is not a susceptibility factor for the development of MS, but is probably to influence the course of MS, possibly contributing to slow down the progression of the disease.  相似文献   
55.
目的 研究D10S2325基因座等位基因和基因型频率在华东地区汉族群体的分布情况,评价该基因座在华东汉族人群的法医学应用价值。方法 用PCR扩增、非变性聚丙烯酰胺凝胶垂直电泳、银染显色方法检测D10S2325基因座的遗传多态性。结果 在华东地区汉族人群中共检出12个等位基因(6~17),其CE值和DP值分别为0.628和0.948。结论 D10S2325等位基因频率分布好,提供的信息量大,对华东地区汉族人群具有较高的非父排除率和个人识别能力,是群体遗传学研究和法医学应用理想的STR位点。  相似文献   
56.
目的:探讨桂附地黄丸防治肺纤维化的作用及机理。方法:用平阳霉素诱导肺纤维化模型大鼠后,用药组每天灌胃桂附地黄丸,第28d后处死各组大鼠,观察、比较各组大鼠肺部病理组织学改变及肺组织中白细胞介素10(IL-10)的表达。结果:桂附地黄丸组、强的松对照组肺纤维化程度显著低于模型对照组(P〈0.05),而肺组织IL-10的表达显著高于模型对照组;且桂附地黄丸组IL-10的表达显著高于强的松对照组。结论:桂附地黄丸能明显减轻平阳霉素所致的大鼠肺纤维化程度,并能显著增强IL-10的表达。  相似文献   
57.
Selected media were compared for primary isolation and detection of oral treponemes from clinical samples. Forty-eight subgingival plaque samples from 45 patients suffering from periodontitis were anaerobically cultivated for 2 weeks at 37°C. Of the 9 media studied, Medium 10 (M10), which was supplemented with 10% rabbit serum and incubated using the plate-in-bottle method, supported the highest colony-forming units of the anaerobes. The treponemal colonies were detected at least on one medium from 83% of the subgingival plaque samples. The new oral spirochete medium in an anaerobic chamber supported the highest detection frequency of the oral treponemes (64% of samples); however, M10 in the plate-in-bottle was found to produce the highest colony-forming unit recovery of the oral treponemes (median 3.6% of the total colony-forming units). This study suggests that M10 in the plate-in-bottle and new oral spirochete medium in the anaerobic chamber are essential in cultivating oral treponemes.  相似文献   
58.
风湿性心脏病二尖瓣置换术中细胞因子水平的变化   总被引:1,自引:0,他引:1  
目的测定风湿性心脏病二尖瓣置换术中细胞因子水平,了解它们的变化规律。方法 11例体外循环(CPB)下二尖瓣置换术患者,分别于术前,主动脉阻断前,主动脉阻断后5min,主动脉开放后10min、1h、2h、4h、24h测定白介素6(IL-6)、白介素8(IL-8)、白介素10(IL-10)以及肿瘤坏死因子(TNF)。结果IL-6、IL-8、IL-10水平在CPB开始后逐渐升高,在主动脉开放后2h左右达到高峰(P<0.01)。之后逐渐下降,到主动脉开放后24h已显著下降。TNF水平在CPB开始后逐渐升高,在主动脉开放后24h仍维持在很高的水平(P<0.01)。结论CPB下二尖瓣置换术中既有促炎因子水平的升高,又有抗炎因子的激活。  相似文献   
59.
PROBLEM: In the presence of progesterone lymphocytes of pregnant women release a 34- kDa protein named the progesterone-induced blocking factor (PIBF). PIBF mediates the immunomodulatory and anti-abortive effects of progesterone and its presence is related to the outcome of pregnancy. PIBF induces production of Th2 type cytokines by activated lymphocytes. The in vivo relationship between PIBF- and cytokine production of pregnancy lymphocytes and the outcome of pregnancy was investigated. METHOD OF STUDY: Interleukin (IL)-12 and IL-10 production and PIBF expression in peripheral lymphocytes of 111 healthy pregnant women and 120 women at risk for premature pregnancy termination were detected by immunocytochemistry. RESULTS: We found increased IL-12 and low PIBF and IL-10 expression on lymphocytes of “risk” patients, and a high rate of IL-10 and PIBF positivity on lymphocytes from healthy pregnant women. The cytokine production pattern of the lymphocytes was related to the presence or absence of previous abortions as well as to the outcome of pregnancy. CONCLUSION: These data suggest the involvement of an altered cytokine production pattern in the immunologic effects of progesterone.  相似文献   
60.
目的:研究辅酶Q10(CoQ10)对大鼠阿霉素心脏毒性的保护作用,并探讨可能的机理。方法:采用离体心脏灌流方法,实验分3组:对照组、阿霉素组、CoQ10组,监测大鼠心肌收缩幅度、冠脉流量、心电图的变化,并测定冠脉流出液肌酸磷酸激酶(CPK)活力和大鼠心肌丙二醛含量、超氧化物歧化酶、谷胱甘肽过氧化物酶(GSH-Px)活力以及电镜下超微结构的改变。结果:CoQ10可改善阿霉素引起的大鼠心肌收缩幅度、冠脉流量下降,减少心律失常的发生,降低冠脉流出液CPK活力;CoQ10组心肌丙二醛含量明显低于阿霉素组、SOD和GSH-Px活力高于阿霉素组,电镜下超微结构变化亦优于阿霉素组。结论:CoQ10对阿霉素引起的心脏毒性具有保护作用,其机理可能与CoQ10拮抗阿霉素的氧自由基损伤有关。  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