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   43882篇
  免费   3519篇
  国内免费   1322篇
耳鼻咽喉   213篇
儿科学   996篇
妇产科学   539篇
基础医学   6987篇
口腔科学   889篇
临床医学   3001篇
内科学   6786篇
皮肤病学   785篇
神经病学   3612篇
特种医学   647篇
外国民族医学   7篇
外科学   3427篇
综合类   5861篇
现状与发展   4篇
预防医学   2015篇
眼科学   521篇
药学   6670篇
  4篇
中国医学   2094篇
肿瘤学   3665篇
  2024年   101篇
  2023年   866篇
  2022年   2075篇
  2021年   2004篇
  2020年   1550篇
  2019年   1692篇
  2018年   1663篇
  2017年   1560篇
  2016年   1428篇
  2015年   1536篇
  2014年   2446篇
  2013年   2662篇
  2012年   2177篇
  2011年   2686篇
  2010年   2128篇
  2009年   2140篇
  2008年   2136篇
  2007年   1886篇
  2006年   1744篇
  2005年   1599篇
  2004年   1495篇
  2003年   1291篇
  2002年   1106篇
  2001年   838篇
  2000年   806篇
  1999年   704篇
  1998年   569篇
  1997年   576篇
  1996年   505篇
  1995年   468篇
  1994年   401篇
  1993年   291篇
  1992年   241篇
  1991年   246篇
  1990年   185篇
  1989年   156篇
  1988年   167篇
  1987年   132篇
  1986年   143篇
  1985年   288篇
  1984年   304篇
  1983年   239篇
  1982年   269篇
  1981年   214篇
  1980年   198篇
  1979年   181篇
  1978年   135篇
  1977年   94篇
  1976年   103篇
  1975年   91篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
郑核  钟德玝  苗雄鹰   《中国医学工程》2006,14(4):367-370
目的 检测胆囊癌组织中CD44v5、CD44v6的表达,并探讨其在胆囊癌发生发展过程中的临床病理意义.方法 采用SP免疫组织化学方法,检测49例胆囊癌、10例胆囊结石伴慢性胆囊炎组织和10例正常胆囊组织中CD44v5、CD44v6蛋白表达情况.结果 CD44v5、CD44v6阳性表达率在胆囊癌组织明显高于良性组织.在胆囊癌中,CD44v5基因表达阳性率与组织学分级无关,CD4 4v6基因表达阳性率与组织学分级有关.有淋巴结转移的胆囊癌组织中,CD44v5、CD44v6阳性表达率明显高于无淋巴结转移者.结论 CD44v5、CD44v6可能在胆囊癌的淋巴结转移中起着重要的作用,CD44v5、CD4 4v6可能是了解胆囊癌病变发生发展生物学行为,淋巴结转移的重要生物学指标.  相似文献   
62.
Background and Aims: Chemokines and their receptors have recently been shown to have major roles in cancer metastasis. The aim of this study was to determine whether the interaction between chemokine receptor 6 (CCR6) and its ligand, macrophage inflammatory protein‐3 alpha (MIP‐3α), correlates with metastasis of hepatocellular carcinoma (HCC). Methods: To observe the reaction of CCR6 expressed cancer cells to MIP‐3α stimulation, chemotactic and actin polymerization assays for both CCR6 high cells (HepG2) and CCR6 low cells (MCF‐7) were performed. CCR6 mRNA levels in tumor specimens from 30 HCC patients were quantified by real‐time polymerase chain reaction. Patients were classified into two groups, high (≥ 20 copies; n = 10) CCR6 and low (<20 copies; n = 20) CCR6 on the basis of CCR6 expression, and the groups were compared with respect to clinicopathological features. Results: When HepG2 cells (CCR6 high) were stimulated with MIP‐3α, they migrated in a dose‐dependent manner, and formation of pseudopodia was observed. These phenomena were not observed in the CCR6 low cells. The incidence of intrahepatic metastasis was higher in the high CCR6 expression group than in the low CCR6 expression group (P < 0.05). Disease‐free survival was significantly poorer in the high CCR6 expression group than in the low CCR6 expression group (P < 0.05). Conclusions: It was indicated that CCR6 might be associated with intrahepatic metastasis of HCC and might be able to become one of the prognostic factor after hepatic resection for HCC.  相似文献   
63.
64.
65.
Itiswell knownthatimmune inflammatorymechanism playsanimportantroleinpsoriasis .Therelationshipbetweenchemokine ,receptorsandpsori asishasbeenconfirmed[1] .CCchemokineligand 2 0(CCL2 0 )isanewmemberinthefamilyof β chemokineandalsotheonlyligandofCCchemoki…  相似文献   
66.
外阴尖锐湿疣人乳头瘤病毒感染的检测与分型   总被引:2,自引:0,他引:2  
目的 了解患外阴尖锐湿疣人乳头瘤病毒(HPV)6型和11型的感染情况及PCR方法对尖锐湿疣诊断与分型的临床意义。方法 采用PCR方法测定160例尖锐湿疣患病题组织或分泌物中HPV6/11型及HPVl6/18型的感染率。结果 HPV6/11型感染率为95%(152/160),HPVl6/18型感染率为5%(8/160),HPV6/11型 HPVl6/18型混合感染率为1.3%(2/160)。结论 外阴尖锐湿疣患以HPV6型和11型感染为主。PCR方法是一种比较适合临床HPV检测与分型的极为敏感和特异的诊断方法。  相似文献   
67.
Summary We have studied the hypoalgesic effect of codeine (100 mg) after blocking the hepatic O-demethylation of codeine to morphine via the sparteine oxygenase (CYP2D6) by quinidine (200 mg). The study was performed in 16 extensive metabolizers of sparteine, using a double-blind, randomized, four-way, cross-over design. The treatments given at 3 h intervals during the four sessions were placebo/placebo, quinidine/placebo, placebo/codeine, and quinidine/codeine. We measured pin-prick pain and pain tolerance thresholds to high energy argon laser stimuli before and 1, 2, and 3 h after codeine or placebo.After codeine and placebo, the peak plasma concentration of morphine was 6–62 (median 18) nmol·.l–1. When quinidine pre-treatment was given, no morphine could be detected (<4 nmol·l–1) after codeine. The pin-prick pain thresholds were significantly increased after placebo/codeine, but not after quinidine/codeine compared with placebo/placebo. Both placebo/codeine and quinidine/codeine increased pain tolerance thresholds significantly. Quinidine/codeine and quinidine/placebo did not differ significantly for either pin-prick or tolerance pain thresholds.These results are compatible with local CYP2D6 mediated formation of morphine in the brain, not being blocked by quinidine. Alternatively, a hypoalgesic effect of quinidine might have confounded the results.  相似文献   
68.
Evidence to suggest the presence of abnormal metabolism of oxygen free radicals in progressive muscular dystrophy is presented using an animal model. In the superficial pectoral muscles of dystrophic chickens, enzyme activities regulating the metabolism of oxygen free radicals, i.e., catalase, superoxide dismutases and glutathione peroxidase, were significantly elevated within 1 week of hatching. Activities of related enzymes, i.e., glutathione reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase were also elevated. In contrast, the specific activity of phosphofructokinase, the rate-limiting enzyme of the glycolytic pathway, was normal during the first 4-week period. These results suggest that there is an increased turnover of oxygen free radicals in the dystrophic muscle. This concept appears important in a further investigation of the pathogenesis and treatment of progressive muscular dystrophies.  相似文献   
69.
随着工业贮存期的延长,啤酒酵母细胞的存活率及对葡萄糖连续磷酸化的速率迅速下降,1,6-二磷酸果糖在发酵液中的浓度由贮存前的75g/L降至贮存2个星期时的30g/L。  相似文献   
70.
Bilateral six-hydroxydopamine (6-OHDA) lesions were placed in the amygdala of rats self-administering cocaine (1.5 mg/kg per injection i.v.) under a progressive ratio schedule of reinforcement. Post-lesion access to three doses of cocaine (1.5, 0.75 and 0.37 mg/kg per injection i.v.) revealed a lesion effect only at the highest dose. At this dose, the lesion caused a significant increase in breaking point. No change in the breaking point was produced at the lower two doses. The biochemical results show a significant reduction in dopamine and DOPAC levels within the amygdala and an increase in dopamine within the NACC. In contrast, noradrenaline and serotonin (5-HT) levels were unaffected by the lesion in any of the dissected areas. These results demonstrate that no specific effect on cocaine reinforcement was produced by 6-OHDA lesions of the amygdala. The possibility that the lesion may have attenuated the anxiogenic qualities of the high dose of cocaine is discussed.  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