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   11655篇
  免费   1258篇
  国内免费   787篇
耳鼻咽喉   116篇
儿科学   231篇
妇产科学   106篇
基础医学   1322篇
口腔科学   206篇
临床医学   1557篇
内科学   1644篇
皮肤病学   107篇
神经病学   598篇
特种医学   398篇
外国民族医学   5篇
外科学   1247篇
综合类   2107篇
现状与发展   4篇
预防医学   1043篇
眼科学   255篇
药学   1223篇
  11篇
中国医学   676篇
肿瘤学   844篇
  2024年   41篇
  2023年   170篇
  2022年   428篇
  2021年   598篇
  2020年   452篇
  2019年   379篇
  2018年   435篇
  2017年   406篇
  2016年   383篇
  2015年   558篇
  2014年   713篇
  2013年   701篇
  2012年   961篇
  2011年   1076篇
  2010年   709篇
  2009年   508篇
  2008年   622篇
  2007年   640篇
  2006年   638篇
  2005年   564篇
  2004年   362篇
  2003年   325篇
  2002年   274篇
  2001年   243篇
  2000年   258篇
  1999年   235篇
  1998年   111篇
  1997年   144篇
  1996年   94篇
  1995年   101篇
  1994年   92篇
  1993年   63篇
  1992年   61篇
  1991年   57篇
  1990年   58篇
  1989年   42篇
  1988年   44篇
  1987年   27篇
  1986年   15篇
  1985年   22篇
  1984年   19篇
  1983年   12篇
  1982年   10篇
  1981年   8篇
  1979年   5篇
  1975年   4篇
  1974年   5篇
  1969年   3篇
  1968年   3篇
  1966年   4篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
61.
目的探讨API2-MALT1融合基因变异体在粘膜相关淋巴组织结外边缘区B细胞淋巴瘤(extranodal marginal zone B—cell lymphoma of mucosa—associated lymphoid tissue,MALT)中的分布特点及其转录与肿瘤凋亡的关系。方法将逆转录-聚合酶链反应和巢式聚合酶链式反应结合,检测62例不同部位MALT淋巴瘤中API2-MALT1融合基因的多种变异体;通过TdT介导脱氧核苷酸缺口末端标记技术进行肿瘤细胞的原位凋亡检测;通过逆转录-聚合酶链反应和免疫组化染色检测API2的mRNA和蛋白水平。结果62例MALT淋巴瘤中28例检出API2-MALT1融合基因(45.16%),为变异体A1446-M1123或A1446-M814,但未检出A1446-M541和A1446-M1150。A1446-M1123(18/28)的检出明显多于A1446-M814(10/28)。融和基因转录在甲状腺MALT淋巴瘤中检出最低,在其它部位的分布无差异。在API2-MALT1^ 组(API2-MALT1mRNA表达阳性组)肿瘤凋亡水平明显高于API2-MALT1^-组(API2-MALT1mRNA表达阴性组),API2的mRNA和蛋白水平低于阴性组。A1446-M1123^ 与A1446-M814^ 病例之间凋亡和API2的变化无差异。结论MALT淋巴瘤中t(11;18)(q21;q21)的发生有部位差异,A1446-M1123可能是中国人MALT淋巴瘤中API2-MALT1融合基因变异体的主要类型。API2-MALT1融合基因转录与MALT淋巴瘤的凋亡水平和API2的变化有关。  相似文献   
62.
本文应用聚合酶链反应技术检测恙虫病立克次体实验感染的恙螨体内立克次体的动态变化,通过人工腹腔接种而感染的恙螨成虫,恙虫病立克次体至少能在其体内生存360天和经卵传递4代;通过未食幼虫叮咬病小鼠而感染的恙螨,经饱蚴、若蛹、若虫、成蛹和成虫阶段,恙虫病立克次体检测均呈阳性,至少能在成虫期体内生存270天和经卵传递1代。  相似文献   
63.
Osteoporosis and obesity are two severe complex diseases threatening public health worldwide. Both diseases are under strong genetic determinants as well as genetically correlated. Aiming to identify pleiotropic genes underlying obesity and osteoporosis, we performed a bivariate genome-wide association (GWA) meta-analysis of hip bone mineral density (BMD) and total body fat mass (TBFM) in 12,981 participants from seven samples, and followed by in silico replication in the UK biobank (UKB) cohort sample (N = 217,822). Combining the results from discovery meta-analysis and replication sample, we identified one novel locus, 17q21.31 (lead SNP rs12150327, NC_000017.11:g.44956910G > A, discovery bivariate P = 4.83 × 109, replication P = 5.75 × 105) at the genome-wide significance level (ɑ = 5.0 × 10−8), which may have pleiotropic effects to both hip BMD and TBFM. Functional annotations highlighted several candidate genes, including KIF18B, C1QL1, and PRPF19 that may exert pleiotropic effects to the development of both body mass and bone mass. Our findings can improve our understanding of the etiology of osteoporosis and obesity, as well as shed light on potential new therapies.Subject terms: Genome-wide association studies, Gene expression profiling  相似文献   
64.
65.
Brown-Norway (BN) rats develop tubulointerstitial nephritis (TIN) after immunization with bovine tubular basement membrane (TBM) and adjuvants. Daily subcutaneous injections (either on Days 0-7 or Days 0-14) of (15S)-15-methyl prostaglandin E1 (M-PGE1) at a dose of 1 mg/kg/day markedly inhibited or completely abrogated the development of both the acute polymorphonuclear (Day 10) and the subsequent mononuclear (Day 14) inflammatory phases of BN rat TIN. Circulating anti-TBM antibody in Days 0-7 M-PGE1-treated rats was moderately diminished on Day 8 after immunization but not on Day 14. Circulating anti-TBM antibody in Days 0-14 M-PGE1-treated rats was only slightly diminished on Day 14. In experiments to test the effect of M-PGE1 on the elicitation phase of humorally mediated inflammation, M-PGE1 inhibited the acute inflammatory response observed 6 hours after intradermal injection of particulate TBM into TBM-sensitized BN rats. The inflammation in these skin tests was demonstrated by passive transfer experiments to be humorally mediated. The inhibition of acute humorally mediated intradermal inflammation was not attributable to neutropenia, because M-PGE1 caused a significant neutrophilia as demonstrated by peripheral blood smears. Although the inhibition of TIN in Days 0-14 M-PGE1-treated rats may have been due, in part, to dysfunction of the elicitation phase of humorally mediated inflammation, the inhibition of TIN in Days 0-7 M-PGE1-treated rats was more likely secondary to the diminished induction of either humoral or cellular immunity.  相似文献   
66.
Hu H  Tang KF  Chua YN  Lu J  Feng P  Chew CT  Chan SH 《Human pathology》2004,35(6):722-728
Interleukin-18 (IL-18) is a single-chain cytokine that is produced by various cells. With interleukin-12 (IL-12), it synergistically stimulates activated T cells and natural killer (NK) cells to produce interferon-gamma (IFN-gamma). Nasopharyngeal carcinoma (NPC) is the most common form of nasal and nasopharyngeal malignancy, and in NPC tumor tissues there is an intense leukocyte infiltration comprising predominantly T cells and macrophages. We previously showed an increased expression of IFN-gamma in the infiltrating T cells. To identify the cells that provide IL-12 and IL-18 for stimulating the expression of IFN-gamma in activated T cells, NPC cell lines CNE-2 and HK-1, as well as biopsies obtained from NPC and control individuals, were examined. CNE-2 and HK-1 cells were found to express messenger RNA encoding IL-18, but not IL-12. Secreted IL-18 was detected in the culture supernatant. Addition of a caspase-1 inhibitor decreased the secretion level, indicating that this IL-18 secretion was caspase-1 dependent. Moreover, the in vitro IL-18 production in NPC cell lines correlated with the NPC tumor cells in situ. NPC tumor cells in the biopsies produced IL-18, as detected by immunohistochemistry and immunofluorescent double staining. In contrast, IL-18 expression was not observed in the control biopsies. We suggest that IL-18 secreted by NPC tumor cells plays a role in initiating the leukocyte infiltration process. IL-18 stimulates T cells and NK cells to produce IFN-gamma, which consequently activates macrophages and other immune cells to secrete chemokines to start a leukocyte recruitment cascade.  相似文献   
67.
目的研究社区老年人的心理健康状况及其心理卫生保健模式。方法采用心理调查问卷并进行统计分析,结果社区老年人心理健康水平与全国成人相比存在明显差异。结论本研究顾示,社区老年人心理健康问题突出,对此提出相应心理卫生保健模式以期改善老年人心理健康状况。  相似文献   
68.
Objective To investigate the level of the serum chemokine RANTES and its correlation with serum biochemical indices of liver function test, HBeAg and HBV DNA load in patients with chronic hepatitis B.Methods 144 patients with chronic hepatitis B (observed group) and 18 normal cases (control group) were enrolled in this study. The serum level of chemokine RANTES was detected with an ABC-ELISA assay. Statistical analysis was performed on the software of SPSS13.0. Results The serum chemokine RANTES level in the observed group (3930.12 ng/ml±2856.96) ng/ml was significantly higher than that in the control group (329.46 ng/ml±152.23) ng/ml. The results from the observed group indicated the positive correlation of serum RANTES level with indices of liver function test, including ALT (r=0. 197, P=0.018), AST(r=0.239, P=0.004) and TBil (r=0.316, P=0.001), but did not with PTA (r=-0.078, P=0.357). Neither difference of serum chemokine RANTES level between HBeAg-positive group and HBeAg-negative group nor that between high HBV DNA load group (≥105 copies/ml) and low HBV DNA load group (< 105 copies/ml) were statistically significant (P=0.407 and 0.185, respectively). Conclusions Serum chemokine RANTES level in patients with chronic hepatitis B elevates significantly and is not affected by HBeAg or HBV DNA load. Its positive correlation with indices of liver function test indicates that RANTES might play an important rule in the pathogenesis of chronic hepatitis B.  相似文献   
69.
急性鸭乙型肝炎病毒感染病毒清除机理研究   总被引:2,自引:0,他引:2  
目的 :进一步阐明嗜肝病毒自然感染过程中病毒清除机理。方法 :7只 2~ 3月龄成年重庆麻鸭静脉接种 10~ 2 0mlDHBV阳性血清 (5× 10 8~ 1× 10 9genome) ,接种后每周采血检测外周血中DHBVDNA、DHBsAg和特异抗体的产生 ;感染后第10、35天分离外周血单个核细胞用于抗原特异细胞增殖实验 ;第 5、30、6 0天取肝组织标本进行DHBVDNASouthern杂交、DHB sAg免疫组化及肝组织病理检测。结果 :DHBV感染成年鸭在 1~ 2w潜伏期后出现急性、一过性感染 ,感染高峰期肝内存在多拷贝的DHBV所有复制中间体形式 ,包括cccDNA。进一步分析显示病毒血症的消失是在快速抗原特异细胞增殖反应和高滴度特异抗体产生之后 ;与此同时 ,整个急性感染期间 ,肝细胞并无明显的损害。结论 :非细胞直接损伤机制在嗜肝病毒清除过程中发挥了重要作用。  相似文献   
70.
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