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   89604篇
  免费   8824篇
  国内免费   7345篇
耳鼻咽喉   652篇
儿科学   830篇
妇产科学   986篇
基础医学   10695篇
口腔科学   1599篇
临床医学   13023篇
内科学   13161篇
皮肤病学   725篇
神经病学   5300篇
特种医学   3173篇
外国民族医学   56篇
外科学   8297篇
综合类   15333篇
现状与发展   22篇
一般理论   13篇
预防医学   5799篇
眼科学   2946篇
药学   9291篇
  102篇
中国医学   5819篇
肿瘤学   7951篇
  2024年   313篇
  2023年   1522篇
  2022年   4289篇
  2021年   5186篇
  2020年   3936篇
  2019年   3208篇
  2018年   3428篇
  2017年   2874篇
  2016年   2822篇
  2015年   4296篇
  2014年   5279篇
  2013年   4463篇
  2012年   6566篇
  2011年   7604篇
  2010年   4572篇
  2009年   3587篇
  2008年   4582篇
  2007年   4489篇
  2006年   4625篇
  2005年   4652篇
  2004年   2739篇
  2003年   2664篇
  2002年   2222篇
  2001年   1938篇
  2000年   2058篇
  1999年   2160篇
  1998年   1456篇
  1997年   1379篇
  1996年   1106篇
  1995年   1030篇
  1994年   847篇
  1993年   545篇
  1992年   606篇
  1991年   512篇
  1990年   471篇
  1989年   427篇
  1988年   356篇
  1987年   299篇
  1986年   228篇
  1985年   180篇
  1984年   81篇
  1983年   50篇
  1982年   41篇
  1981年   37篇
  1980年   24篇
  1979年   21篇
  1975年   2篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
重症肌无力术后延长拔管时间的临床价值   总被引:6,自引:0,他引:6  
目的 探讨重症肌无力 (MG)胸腺切除术后 ,延长气管拔管时间 ,减少气管切开的价值。方法 回顾分析 1978年至 2 0 0 2年 12月行MG胸腺切除 2 36例 ,按时间分A组 :1996年 12月以前手术者116例 ,对术后可能发生肌无力危象的高危因素病人施行预防性气管切开 ;B组 :1997年后手术 12 0例 ,对具发生危象高危因素者采用延长气管拔管时间 ,并对两组危象发生率及气管切开率进行比较。结果 全组发生危象 4 4例 (18 6 % ) ,气管切开 4 6例 (ARDS 1例除外 )占 19 5 %。其中A组发生危象 2 3例(19 8% ) ,气管切开 34例 (2 9 3% ) ;B组发生危象 2 1例 (17 5 % ) ,气管切开 12例 (10 % )。两组危象发生率无明显差异 ,但A组的气管切开率明显高于B组 (P <0 0 0 1)。结论 对MG胸腺切除术后具发生危象高危因素病人 ,采用延长气管插管时间及辅助通气 ,可显著减少气管切开率。  相似文献   
132.
人白细胞介素12双亚基共表达真核载体的构建   总被引:2,自引:0,他引:2  
目的:为满足基因治疗的需要构建人白细胞介素12(hIL-12)双亚基共表达质粒。方法:先从人胚肾组织的逆转录产物中用PCR方法扩增出它的两个亚基P40和P35的cDNA全长,分别克隆入真核表达载体pcDNA3.1( /-)中构建单亚基质粒——P( )/P40和P(-)/P35,然后再将二者串联克隆入真核表达载体poDNA3.1( )中得到P( )/IL-12质粒。脂质体转染HepG2后24,48h ELISA检测细胞培养上清内hIL-12蛋白质表达。结果:P( )/IL-12质粒经酶切和测序证明两亚基连接方向正确,序列无突变;ELISA检测细胞上清结果证实可表达hIL-12蛋白质。结论:成功构建P40和P35双亚基真核共表达质粒——P( )/IL-12,为模拟hIL-12生理表达方式,简化hIL-12基因治疗操作奠定了基础。  相似文献   
133.
腹腔镜肾上腺肿瘤切除术75例报告   总被引:2,自引:0,他引:2  
目的探讨腹腔镜下肾上腺肿瘤切除的方法和临床应用价值.方法1999年1月~2004年6月75例患者行腹腔镜肾上腺肿瘤切除术,其中采用经腹腔途径51例和经腹膜后途径24例.结果手术时间平均为(170.16±33.81)min,术中的出血量平均为(70.82±37.15)ml.术后平均住院时间为(5.87±1.01)d.中转开放手术2例(2.67%).发生并发症4例(5.33%),分别为膈肌损伤、胰腺损伤、肠道损伤、皮下血肿各1例.结论腹腔镜下行肾上腺肿瘤切除术具有创伤小,术中出血少,术后恢复快等优点,已经成为现代治疗肾上腺肿瘤的金标准.  相似文献   
134.
BACKGROUND: At present, researches on differentiating from human adipose-derived adult stromal cells (hADASC) to neuron-like cells are focus on inducing by artificial-synthetic compound solution; however, hippocampal astrocyte conditioned medium (HCAM) can induce in vitro differentiation from hADASC to neuron-like cells is still unclear. OBJECTIVE: To observe whether HCAM can induce in vitro differentiation from hADASC to neuron-like cells. DESIGN: Randomized control study. SETTING: Department of Neurology, Taixing People's Hospital; Central Laboratory, North China Coal Medical College. MATERIALS: Donor of adipose tissue was donated by female volunteers suffering from caesarean section in the department of obstetrics & gynecology in our hospital and aged 20-35 years. Adipose tissue was collected from subcutaneous tissue of abdomen during the operation. In addition, 8 male newborn Wistar rats within 24 hours with average body mass of 20 g were provided by Animal Institute of Chinese Academy of Medical Sciences. Rabbit-anti-human Nestin polyclonal antibody, rabbit-anti-human glial fibriliary acidic protein (GFAP) polyclonal antibody, rabbit-anti-human neuro-specific enolase polyclonal antibody and mouse-anti-human microtubal associated protein 2 (MAP-2) polyclonal antibody were provided by Wuhan Boster Company. METHODS: The experiment was carried out in the Central Laboratory of North China Coal Medical College from October 2004 to June 2005. hADASC was cultured with HCAM and its growth and morphological changes were observed under inverted phase contrast microscope. Immunocytochemistry, immunofluorescence and Western blotting were used to evaluate the expressions of Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. MAIN OUTCOME MEASURES: Nestin, which was a specific sign of nerve precursor, neuro-specific enolase and MAP-2, which was a specific sign of nerve cell, and GFAP, which was a specific sign of neuroglial cells. RESULTS: On the 3rd day of culture, partial hADASC started deformation from slender shuttle-shape cells to neuron-like cells. It suggested that cells stretched out apophysis, which were mainly double-pole or multiple-pole cells. Five days later, immunohistochemical detection suggested that expression of Nestin (10.5±0.037) was found out in cells; meanwhile, expressions of GFAP (38.4±0.052) and neuro-specific enolase (NSE) (15.7±0.023) were also found out in cells; however, expression of MAP-2 was not observed. Western blot indicated that, 5 days after effect of HCAM, Nestin was found out in hADASC; meanwhile, expressions of GFAP and neuro-specific enolase were also found out; however, expression of MAP-2 was not observed. CONCLUSION: HCAM can induce the differentiation from hADASC to neuron-like cells in vitro.  相似文献   
135.
皮肤交界性平滑肌瘤的复发与恶性转化   总被引:3,自引:0,他引:3  
目的探讨皮肤交界性平滑肌瘤的复发与恶性转化。方法复习2例皮肤交界性平滑肌瘤及其复发恶性转化的临床病理特征、免疫组化表型及相关文献。结果2例病变位于下肢和额部,肉瘤组织平滑肌标记阳性。结论少数病理诊断为皮肤平滑肌瘤的病例,虽然浅表且组织形态良性,但其生物学恶性潜能尚不能确定,部分病例复发后可转变为典型的平滑肌肉瘤。  相似文献   
136.
心理支持疗法对机械通气患者应激反应的影响   总被引:2,自引:1,他引:1  
目的 观察心理支持疗法(PST)对ICU患者机械通气应激反应的影响。方法 将34例连续机械通气时间在20h的清醒患者,随机分为采用标准的PST方法进行治疗的观察组和对照组,观察焦虑抑郁程度和应激反应改变情况。结果 对照组患者的焦虑抑郁程度明显高于观察组,部分应激反应激素水平升高幅度也明显大于观察组。结论 PST可通过缓解机械通气患者的焦虑抑郁等不良情绪状态减轻机械通气带来的各种心身应激反应,有利于提高机械通气治疗的有效性和安全性。  相似文献   
137.
学龄前儿童的屈光异常与弱视调查   总被引:7,自引:0,他引:7  
目的了解屈光检查在学龄前儿童弱视普查中的临床用途。方法应用日本尼康手提全自动检影仪对学龄前儿童进行小瞳孔验光,发现屈光有异常的儿童,再进一步进行散瞳检影验光。结果学龄前儿童屈光异常主要以远视散光和混合散光为主,近视与近视散光较少。学龄前儿童屈光异常的发病率是7.87%,弱视发病率为4.04%,接近全国其他同类报告(3.83%)。结论儿童弱视屈光普查优于视力普查,准确性高、效率高。  相似文献   
138.
目的:探讨不同培养阶段骨髓基质干细胞成骨能力的变化及BMP-2对其成骨能力的影响。方法:培养兔骨髓基质干细胞,测定第3代和第18代细胞碱性磷酸酶及骨钙素活性;测定BMP-2对不同培养时间骨髓基质干细胞成骨能力的影响;测定rhBMP-2对细胞增殖的影响。结果:细胞传至第18代后,分泌的骨钙素(OC)水平及ALP活力明显降低,与第3代细胞相比,差异显著(P〈0.05)。第3代细胞在rhBMP-2的诱导下,分泌的OC水平及ALP活力在原基础上进一步升高,与对照组相比,差异显著(P〈0.05)。结第18代细胞在rhBMP-2的诱导下,分泌的OC水平及ALP活力在原基础上升高,与对照组相比,差异不显著(P〉0.05);随培养时间的延长,各组细胞数量均有所增加,rhBMP-2诱导组与对照组细胞无显著性差异(P〉0.05)。细胞的传代次数对细胞增殖无明显影响(P〉0.05)。结论:rhBMP-2对细胞增殖无影响。随着传代次数的增加,骨髓基质干细胞的成骨能力下降,rhBMP-2促进其成骨的能力亦下降。  相似文献   
139.
A genome-wide screen was conducted using a large white sample to identify QTLs for FNCS geometry. We found significant linkage of FNCS parameters to 20q12 and Xq25, plus significant epistatic interactions and sex-specific QTLs influencing FNCS geometry variation. INTRODUCTION: Bone geometry, a highly heritable trait, is a critical component of bone strength that significantly determines osteoporotic fracture risk. Specifically, femoral neck cross-sectional (FNCS) geometry is significantly associated with hip fracture risk as well as genetic factors. However, genetic research in this respect is still in its infancy. MATERIALS AND METHODS: To identify the underlying genomic regions influencing FNCS variables, we performed a remarkably large-scale whole genome linkage scan involving 3998 individuals from 434 pedigrees for four FNCS geometry parameters, namely buckling ratio (BR), cross-sectional area (CSA), cortical thickness (CT), and section modulus (Z). The major statistical approach adopted is the variance component method implemented in SOLAR. RESULTS: Significant linkage evidence (threshold LOD = 3.72 after correction for tests of multiple phenotypes) was found in the regions of 20q12 and Xq25 for CT (LOD = 4.28 and 3.90, respectively). We also identified eight suggestive linkage signals (threshold LOD = 2.31 after correction for multiple tests) for the respective geometry traits. The above findings were supported by principal component linkage analysis. Of them, 20q12 was of particular interest because it was linked to multiple FNCS geometry traits and significantly interacted with five other genomic loci to influence CSA variation. The effects of 20q12 on FNCS geometry were present in both male and female subgroups. Subgroup analysis also revealed the presence of sex-specific quantitative trait loci (QTLs) for FNCS traits in the regions such as 2p14, 3q26, 7q21 and 15q21. CONCLUSIONS: Our findings laid a foundation for further replication and fine-mapping studies as well as for positional and functional candidate gene studies, aiming at eventually finding the causal genetic variants and hidden mechanisms concerning FNCS geometry variation and the associated hip fractures.  相似文献   
140.
背景与目的:功能性消化不良(FD)被认为是一类由不同病理生理原因导致的多种机能紊乱而促发的症状。Rome Ⅱ委员会建议将具有同种病理生理学及临床特征的FD患划分为感觉明显疼痛组和感觉不适组两个亚组。该研究旨在分析显疼痛或感觉不适与病理生理学机制间的关系,评价是否考虑到个体的显性症状将会产生更好的结果。方法:持续性FD患(n=720;489例女性;年龄41.3±0.6岁)填写消化不良调查问卷并确定出最令人烦恼的症状。分析此显症状在人口统计学、临床、病理生理学特点上的相互联系(研究592例患幽门螺杆菌感染、胃排空情况,对332例患行胃敏感性、顺应性试验)。结果:根据Rome Ⅱ标准,22%疼痛明显,78%不适感明显。疼痛明显的患超敏性的发生率较高(44% vs 25%),且在这些病例中观察到的胃排空迟缓较少出现(16% vs 26%),但是有较多的重叠。详细分析表明可能有8种消化不良症状其中之一较为突出。  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