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   99467篇
  免费   8741篇
  国内免费   4833篇
耳鼻咽喉   723篇
儿科学   2098篇
妇产科学   1644篇
基础医学   11388篇
口腔科学   2181篇
临床医学   9940篇
内科学   16003篇
皮肤病学   1431篇
神经病学   7718篇
特种医学   1856篇
外国民族医学   31篇
外科学   7911篇
综合类   16922篇
现状与发展   13篇
预防医学   9039篇
眼科学   2878篇
药学   9536篇
  46篇
中国医学   3562篇
肿瘤学   8121篇
  2024年   278篇
  2023年   1223篇
  2022年   2728篇
  2021年   3600篇
  2020年   3235篇
  2019年   2921篇
  2018年   2906篇
  2017年   3331篇
  2016年   3659篇
  2015年   3557篇
  2014年   6274篇
  2013年   6925篇
  2012年   6415篇
  2011年   7080篇
  2010年   5928篇
  2009年   5548篇
  2008年   5780篇
  2007年   5756篇
  2006年   5163篇
  2005年   4584篇
  2004年   3878篇
  2003年   3344篇
  2002年   2763篇
  2001年   2389篇
  2000年   2009篇
  1999年   1718篇
  1998年   1476篇
  1997年   1258篇
  1996年   1136篇
  1995年   1032篇
  1994年   843篇
  1993年   660篇
  1992年   582篇
  1991年   445篇
  1990年   416篇
  1989年   313篇
  1988年   254篇
  1987年   202篇
  1986年   168篇
  1985年   264篇
  1984年   211篇
  1983年   132篇
  1982年   187篇
  1981年   108篇
  1980年   119篇
  1979年   73篇
  1978年   44篇
  1977年   38篇
  1976年   31篇
  1975年   27篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
A portion of transplanted islets is lost during engraftment as a result of stressful events, involving hypoxia and production of proinflammatory molecules by islets. Two of these molecules (monocyte chemoattractant protein-1, CCL2/MCP-1 and tissue factor, TF) are directly correlated with reduced graft function. We evaluated which factors reduce islet proinflammatory conditions. In particular the effects of different culture media supplemented with proteins or antioxidant agents on CCL2/MCP-1 and TF human islet release were evaluated. We observed that human islets after culture in final wash culture medium (FW) significantly decreased CCL2/MCP-1 release and TF production compared with CMRL and M199. These effects were independent from the type of protein added to the media (human serum, human albumin, fetal calf serum). Glutathione in FW further decreased CCL2/MCP-1 in a dose-dependent manner. Culture conditions can modulate the proinflammatory state of islets, and could be used in clinical islet transplantation to reduce inflammation during engraftment.  相似文献   
82.
Alzheimer's disease (AD) is a neurodegenerative disorder with mixed cognitive and behavioural clinical manifestations. The possession of apolipoprotein-E (ApoE) epsilon4 allelic variant is one of the most important risk factors for developing late-onset AD (LOAD). In this study we analysed the relationship between the entire range of behavioural symptoms, cognitive deficit, and sociodemographic characteristics and ApoE epsilon4 allele possession with multivariate logistic regression models in LOAD patients. Patients included (n = 171) were consecutively admitted in a memory clinic for the first diagnostic visit. Levels of behaviour and cognition within the last month were assessed by the Neuropsychiatric Inventory and Mini Mental State Examination. Presence of clinically significant psychosis, delusions and hallucinations at the early stage of the illness, from the onset to the first visit, was measured with diagnostic criteria. ApoE epsilon4 allele possession was associated with increased levels of delusions within the last month from the first visit (OR 1.23; 95% CI 1.01-1.50; P < 0.05) and with the presence of categorical delusions at the early stage until the first visit (OR 3.11; 95% CI 1.21-8.01; P < 0.02). In this study, which considers the entire range of behavioural expressions in LOAD patients at the early stage of the illness, the relationship between behaviour and ApoE epsilon4 allele is confirmed for delusions only.  相似文献   
83.
论高校大学生绿色网络环境的营造   总被引:2,自引:0,他引:2  
介绍了网络文化的迅猛发展对高校大学生的学习方式、生活方式、交往方式产生了巨大冲击,尤其对大学生的身心发展产生了不可忽视的消极影响。指出在高校信息化校园建设中,要加强网络文明的建设,提倡和重视绿色网络,并且从高校大学生的实际出发,努力营造一个健康、文明、有序、安全、具有活力、没有污染的绿色网络环境。  相似文献   
84.
Radiotherapy(RT)is an important ap-proach for treatment of esophageal carcinoma(EC),especially for patients who have missedthe chance of surgical section.The efficacy ofRTis not satisfactory for its1-year,3-year and5-year survival rates being merely50%,20%,and10%respectively(1).Researches in recent years showed thatbetter efficacy can be obtained by combiningRTwith Chinese herbal medicines for EC thatincapable to be resected.Kang ai Injection(康艾注射液,KAI)is a Chinese herbal prep-arati…  相似文献   
85.
血管内皮生长因子与妊娠高血压综合征发病的关系   总被引:2,自引:0,他引:2  
谢兰  罗军  陈廉  邹冰玉  杨年 《四川医学》2003,24(8):773-775
目的 探讨血管内皮生长因子 (VEGF)在妊娠高血压综合征发病中的作用。方法 分别采用酶联免疫吸附试验检测 40例妊高征孕妇的血清VEGF水平 ,免疫组化检测胎盘及蜕膜组织VEGF及CD3 4表达情况 ,35例正常孕妇作对照。结果 ①妊高征组孕妇的外周血VEGF水平及胎盘组织MVD明显低于正常妊娠组 (P <0 0 5 ) ;②两组胎盘绒毛滋养叶细胞和蜕膜组织中均有VEGF阳性表达 ,胎盘组织强阳性表达高于蜕膜。与对照组比较 ,其胎盘组织VEGF强阳性表达的轻度妊高征无显著性差异 ;而中度和重度妊高征与对照组相比 ,则明显降低 ,差异显著 (P <0 0 5 )。各组孕妇蜕膜组织中VEGF的表达强度和差异无显著性。③孕妇外周血VEGF水平与新生儿出生体重 (r =0 2 9,P <0 0 5 )和胎盘重量 (r =0 34,P <0 0 1)均存在直线正相关关系。结论 妊高征患者血清VEGF水平和胎盘组织MVD降低 ,胎盘组织VEGF表达明显下降 ,都可能在妊高征的发病中起一定的作用。  相似文献   
86.
星形胶质细胞瘤伽玛刀治疗的疗效与影响因素   总被引:6,自引:0,他引:6  
目的分析星形胶质细胞瘤伽玛刀(γ-刀)治疗的疗效与影响因素.方法回顾性分析48例星形胶质细胞瘤病人的γ-刀治疗结果.以性别、有无普通放疗经过、有无化疗经过、边缘剂量、病灶的平均直径、病变的病理等级、影像学上有无相对较清楚的边界为治疗结果影响因素,判定标准以病灶缩小为有效,采用logistic回归模型,确定多因素条件下治疗结果的影响因素.结果有效32例(66.7%),logistic回归模型分析表明:病理等级和病灶平均直径为与肿瘤控制有关的影响因素.结论γ-刀对星形胶质细胞瘤的治疗有一定的意义.  相似文献   
87.
目的探讨酪氨酸激酶抑制剂(Tyrosine kinase inhibitor,TKI)对培养气管上皮细胞生长的影响.方法通过MMT法、3H-胸腺嘧啶(3H-TdR)掺入法及流式细胞计数,观察3种TKIs:Tyrphostin AG1478、Genistein(Sigma)及金转停对原代培养的大鼠气管上皮细胞增殖、周期及凋亡的影响,以及TKIs对表皮生长因子(EGF)的阻断作用.结果MTT法显示3种TKI均对气管上皮细胞的生长具有时间和剂量依赖性抑制作用,同时,TKI阻断EGF对气管上皮细胞生长的刺激作用,3种TKIs的作用无明显差异;1μmol/L的Tyrphostin AG1478、Genistein及金转停分别使气管上皮细胞的TdR掺入率降低18.3%、20.9%及19.7%,与MTT比色法结果一致.同时,Tyrphostin AG1478不仅加速气管上皮细胞的凋亡而且阻止细胞有丝分裂.TKIs可阻断表皮生长因子(EGF)对气管上皮细胞生长的刺激作用.结论TKIs不仅抑制对原代培养的大鼠气管上皮细胞的生长,加速其凋亡,而且可阻断EGF对气管上皮细胞生长的刺激作用,3种抑制剂的作用无明显差异.  相似文献   
88.
Clinical efficacy, safety and pharmacokinetic properties of the high-purity double-virus inactivated plasma-derived factor VIII concentrate Haemoctin SDH (pdFVIII) were evaluated in three prospective open-label uncontrolled studies in previously treated patients (PTPs) with severe haemophilia A. The pharmacokinetic properties assessed at baseline and after 3 months of treatment are in accurate accordance with published data and remain unchanged over time (study A, n = 12). Mean terminal elimination half-life was 11.8 and 11.9 h, mean incremental recovery (IU dL(-1)/IU kg(-1)) was 2.3 and 2.0, respectively. Long-term efficacy and safety, in particular the potential immunogenicity, were investigated in a total of 53 PTPs (studies A and B) treated prophylactically and on-demand, as required. PdFVIII has shown to be effective in preventing and controlling bleeding episodes; 23.5% of patients were free of bleeding events. A total of 177 haemorrhages occurred with 74.0% resolving after a single infusion, 87.6% within two infusions. 98.3% of responses reported on haemorrhages were rated as 'excellent' or 'good'. Moreover, 'excellent' haemostatic efficacy has been demonstrated in 10 surgical procedures including general and severe orthopaedic interventions (study C). No complication occurred in any surgery. Few adverse events were reported, one patient developed a high-titre FVIII inhibitor without clinical relevance. In all three studies, over 6 million units were administered in nearly 4300 infusions, approximately 94% units or infusions were given for prophylaxis and only 6% for treatment on-demand. In conclusion, pdFVIII has shown to be effective, safe and well tolerated in long-term prophylaxis and treatment on-demand as well as after minor and major surgical procedures.  相似文献   
89.
Neuromuscular biopsy is still an essential method for diagnosing vasculitic neuropathy, although its diagnostic sensitivity is at most 60%. Our objective was to examine the expression of hypoxia‐inducible factor 1α (HIF‐1α) in peripheral nerves and to evaluate its usefulness in diagnosing vasculitic neuropathy, especially for discrimination from other axonal neuropathies. Forty‐one patients with vasculitic neuropathy consisting of 20 definite, 14 probable and seven possible diagnoses, 15 patients with metabolic neuropathy, five with motor neuron disease and six with chronic inflammatory demyelinating polyneuropathy were included. Nerve biopsy specimens were immunohistochemically examined for HIF‐1α and various cell markers. Distinct immunoreactivity (IR) was observed in nuclei of endoneurial cells in 54% (22/41) of vasculitic patients, while specimens from metabolic neuropathies showed less nuclear IR and the difference of mean density of HIF‐1α‐positive nuclei was significant. Two patients with possible vasculitis who showed HIF‐1α‐positive nuclei in endoneurium, were later confirmed to have vasculitis by skin biopsies. Most of the cells expressing HIF were demonstrated to be Schwann cells. There was a trend in the vasculitic patients with early phase nerve damage to display higher endoneurial HIF‐1α‐IR. HIF‐1α may be an immunohistochemical marker for vasculitic neuropathy, especially when the observed section contains no vasculitic lesions.  相似文献   
90.
The seven serotypes (A–G) of botulinum neurotoxin (BoNT) are proteins produced by Clostridium botulinum and have multifunctional abilities: (i) they target cholinergic nerve endings via binding to ecto‐acceptors (ii) they undergo endocytosis/translocation and (iii) their light chains act intraneuronally to block acetylcholine release. The fundamental process of quantal transmitter release occurs by Ca2+‐regulated exocytosis involving sensitive factor attachment protein‐25 (SNAP‐25), syntaxin and synaptobrevin. Proteolytic cleavage by BoNT‐A of nine amino acids from the C‐terminal of SNAP‐25 disables its function, causing prolonged muscle weakness. This unique combination of activities underlies the effectiveness of BoNT‐A haemagglutinin complex in treating human conditions resulting from hyperactivity at peripheral cholinergic nerve endings. In vivo imaging and immunomicroscopy of murine muscles injected with type A toxin revealed that the extended duration of action results from the longevity of its protease, persistence of the cleaved SNAP‐25 and a protracted time course for the remodelling of treated nerve–muscle synapses. In addition, an application in pain management has been indicated by the ability of BoNT to inhibit neuropeptide release from nociceptors, thereby blocking central and peripheral pain sensitization processes. The widespread cellular distribution of SNAP‐25 and the diversity of the toxin's neuronal acceptors are being exploited for other therapeutic applications.  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