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   14306篇
  免费   1429篇
  国内免费   1227篇
耳鼻咽喉   69篇
儿科学   177篇
妇产科学   130篇
基础医学   1582篇
口腔科学   326篇
临床医学   1973篇
内科学   2261篇
皮肤病学   155篇
神经病学   813篇
特种医学   504篇
外国民族医学   5篇
外科学   1616篇
综合类   2430篇
现状与发展   4篇
一般理论   1篇
预防医学   975篇
眼科学   419篇
药学   1483篇
  1篇
中国医学   675篇
肿瘤学   1363篇
  2024年   40篇
  2023年   241篇
  2022年   566篇
  2021年   725篇
  2020年   571篇
  2019年   506篇
  2018年   535篇
  2017年   424篇
  2016年   439篇
  2015年   656篇
  2014年   778篇
  2013年   667篇
  2012年   966篇
  2011年   1120篇
  2010年   730篇
  2009年   545篇
  2008年   740篇
  2007年   799篇
  2006年   647篇
  2005年   687篇
  2004年   532篇
  2003年   510篇
  2002年   456篇
  2001年   401篇
  2000年   383篇
  1999年   386篇
  1998年   283篇
  1997年   249篇
  1996年   168篇
  1995年   173篇
  1994年   104篇
  1993年   101篇
  1992年   130篇
  1991年   104篇
  1990年   113篇
  1989年   79篇
  1988年   88篇
  1987年   70篇
  1986年   63篇
  1985年   46篇
  1984年   40篇
  1983年   8篇
  1982年   13篇
  1981年   13篇
  1980年   9篇
  1979年   9篇
  1975年   6篇
  1974年   6篇
  1973年   5篇
  1966年   5篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
微波体模   总被引:9,自引:1,他引:9  
用水、盐,聚氯乙烯粉和羧甲基纤维钠四种材料配制成一种适用的微波体模(模拟肌肉组织)。该体模的复介电系数在300~2500MHz范围内与实际人体肌肉组织的误差≤5%。这种体模的优点是材料立足国内,价廉,室温下配制,使用方便。本文也给出这种体模的温度特性,稳定性和热学特性,供电磁场生物效应和微波热疗等研究使用。  相似文献   
32.
W Mao  L Zeng  Q Ma  Y Chen  Z Dai  P Tang  X Guo  D Li  W Su 《眼科学报》1990,6(3-4):88-90
We report here the preliminary effects of zinc iontophoresis in treatment of 26 Rp patients who had decreased zinc serum level or abnormal ratio of serum copper to zinc. Through more than 20 to 30 times of therapy, the vision of 15.38% eyes increased more than "3 lines", 4% eyes increased more than 5 degrees in the visual field, 13.46% eyes improved in dark adaptation threshold (greater than 1.0), the visual functions of the rest eyes were slightly improved or unimproved. The fundus didn't change before & after treatment. There were no changes of ERG in 8 eyes of 4 cases. In addition, the advantages and disadvantages between Zn iontophoresis and Zn compound taken orally, the improvement of vision by direct electric current therapy, the relationship between the metabolism of Zn element and Vit A and influence of Zn over the mechanism of dark adaptation were also briefly discussed.  相似文献   
33.
目的:寻找番荔枝科假鹰爪属植物假鹰爪Desmos chinensis抗肿瘤活性成分。方法:采用硅胶柱色谱分离化学成分。根据理化性质及波谱分析等方法鉴定结构。结果:从氯仿萃取物中分离鉴定了7个化合物,分别是unon-al(Ⅰ),黄芩素-7-甲醚(Ⅱ),去甲氧杜鹃花素(Ⅲ),去甲氧杜鹃花素-7-甲醚(Ⅳ),苯甲酸(Ⅴ),β-谷甾醇(Ⅵ)和豆甾醇(Ⅶ)。结论:该种植中鉴定的黄酮类化合物均为β-环未取代,  相似文献   
34.
S Jiang  S Yuan  Y Wang  X Chen  Y Song  Y Yang  B Mao 《华西医科大学学报》2000,31(2):191-2, 232
In this study, the chemosensitivity of 36 cases' fresh neuroglioma specimens was examined in vitro with MTT assay. The separation method for single tumor cell, the number of planting of cells, and the dosage and acting time of drugs, which have effects on the results of MTT assay, were studied systematically. On the basis of this experiment, we established a screening method for the chemosensitivity of neuroglioma; it is accurate, rapid, and simple. At the same time, the results showed that neuroglioma was more sensitive to the chemotherapeutic drugs Vm26, DDP and MMC, and the sensitivity varied with not only the drugs but also the individuals.  相似文献   
35.
CD7 and CD57 are related to the differentiation and functional stages of CD8+ T cells. However, the role of their combined presence in CD8+ T cells in patients with chronic hepatitis B virus (HBV) infection, especially those with end-stage liver disease, remains unclear. Blood samples from healthy volunteers and patients with chronic hepatitis B were analyzed via Luminex assay and ELISA to measure plasma cytokine levels. Further, recombinant IL-22 was used to stimulate peripheral blood mononuclear cells from healthy volunteers, and the frequency of CD3+CD4CD7+CD57 T cells and apoptosis rates were investigated via flow cytometry. Patients with end-stage liver disease, particularly those with acute to chronic liver failure, showed decreased CD3+CD4CD7+CD57 T cell frequency. Furthermore, the prevalence of CD3+CD4CD7+CD57 T cells was negatively correlated with disease severity, prognosis, and complications (ascites). We also observed that IL-22 promoted apoptosis and brought about a decrease in the number of CD3+CD4CD7+CD57 T cells in a dose-dependent manner. CD3+CD4CD7+CD57 T cells displayed a B and T lymphocyte attenuator (BTLA)highCD25highCD127high immunosuppressive phenotype and showed low interferon-γ, tumor necrosis factor-α, granzyme A, and perforin expression levels. The present findings will elucidate the pathogenesis of HBV-related end-stage liver disease and aid the identification of novel drug targets.  相似文献   
36.
检测60例中、重度学龄期单纯性肥胖儿童的血液流变学指标,以M超、B超、多普勒血流显像、多普勒组织显像等技术对心功能状况进行了全面检查。结果表明,与正常体重对照组相比,肥胖儿血液流变学各指标均有显著变化(P均<0001),心脏的收缩和舒张功能均受累,血粘度的增加与心功能减低有明显的相关性。提示儿童期的单纯性肥胖已出现了血液流变学特性和心血管功能的异常,随着血粘度的增加,心功能渐减低,血液流变学特性的改变是单纯性肥胖症心血管系统功能受累的病理基础之一。  相似文献   
37.
观察机械性损伤的海马神经细胞在不同浓度高晶体- 高胶体渗透压溶液中容积的变化。取原代培养大白鼠胚胎的海马神经细胞,用超声波机械损伤细胞后暴露于含0.5 g/L、1 g/L和2.5 g/L氯化钠的细胞培养基中15 m in。结果显示机械性损伤的细胞明显肿胀(P< 0.05)。当细胞暴露于不同浓度的高晶体- 高胶体溶液15 m in 后, 细胞容积与同一实验时间的对照值相比明显下降, 并保持至第7 d (P< 0.05)。表明受到机械性损伤的海马神经细胞在高晶体- 高胶体渗透压环境中的容积调节功能丧失或减弱。  相似文献   
38.
Our previous studies have demonstrated that overexpression of recombinant human interleukin-1 receptor antagonist protein (IL-1ra) via gene transfer can reduce ischemic brain injury. However, the mechanism of action of IL-1ra in ischemia is unclear. Since interleukin-1 can up-regulate intercellular adhesion molecules in endothelium, the present study was designed to determine whether overexpression of the IL-1ra can reduce the expression of intercellular adhesion molecule-1 (ICAM-1) after ischemic injury. Normal saline or adenovirus vector (1x109 particles) encoding the human IL-1ra gene (Ad.RSVIL-1ra) or the Escherichia coli LacZ gene (Ad.RSVlacZ) was injected into the right lateral cerebral ventricle of adult CD-1 mice. After five days, permanent middle cerebral artery occlusion (MCAO) was achieved for 24 h using an intraluminal suture. Cerebral blood flow was monitored by transcranial laser Doppler flowmetry to verify the occlusion. ICAM-1 protein was quantified using Western blot analysis and localized using immunohistochemistry. After MCAO, surface blood flow in the ischemic hemisphere was decreased to 9-11% of the baseline. There were fewer ICAM-1 positive vessels in the ischemic cortex of the Ad.RSVIL-1ra transfected mice than in the Ad.RSVlacZ transfected and saline treated mice (138+/-19 vs. 249+/-25, 284+/-22, p<0.05). Western blot analysis shows that ICAM-1 protein decreased 50-60% in the Ad. RSVIL-1ra group compared to the other two groups. There were no significant differences in the numbers of positive vessels in the ischemic basal ganglia and contralateral hemisphere among the three groups. Our studies suggest that IL-1ra overexpression can down-regulate the expression of ICAM-1 in the ipsilateral cortex in ischemic mice. Interleukin-1 may play an important role in the activation of inflammatory reaction during focal cerebral ischemia by promoting leukocyte adhesion on the endothelium cells.  相似文献   
39.
This periodic report includes intermittent results of consecutive pancreaticoduodenal (Pd) and kidney (Kt) transplants in inbred rats and results on double kidney transplants that did not follow sequential transplant protocol. Eight 24-month-old Lewis pancreas, kidney, and aorta served histological controls showing normal histological architecture with no atherosclerosis developed in the aorta. Thirty-four month old pancreas and thirty-two month old kidneys, which resided in young hosts for at least three occasions, appeared as youthful Pd and Kt grafts. They show normal histological appearance for more than the expected life span of a Lewis rat. The fact that not only pancreases but also kidneys outlived their host leads to the study of other different organs' viability as aged valuable grafts. Nevertheless, the threats by the development of atherosclerosis in graft-associated aortas resulted in slow progression of the follow-ups.  相似文献   
40.
电针对去势大鼠外周血淋巴细胞雌激素受体影响的研究   总被引:4,自引:0,他引:4  
目的 从生殖内分泌 -免疫网络角度探讨电针治疗围绝经期综合征的作用机制。方法 以去势大鼠为实验对象 ,取双侧三阴交、太溪、后三里穴 ,采用放射免疫法和流式细胞分析技术 ,观察电针治疗对去势大鼠血清雌激素 (E2 )、促黄体生成素 (LH)、促卵泡生成素(FSH)及外周血淋巴细胞内雌激素受体 (ER)水平的影响。结果 电针可使去势大鼠血清E2 明显升高 ,LH及FSH明显下降 ,外周血淋巴细胞内ER明显升高 ,与造模组比较有显著性差异。结论 电针可明显改善去势大鼠的生殖内分泌功能 ,并能调节免疫细胞的雌激素受体表达。  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