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   36266篇
  免费   2212篇
  国内免费   798篇
耳鼻咽喉   142篇
儿科学   761篇
妇产科学   257篇
基础医学   4760篇
口腔科学   562篇
临床医学   2978篇
内科学   8706篇
皮肤病学   362篇
神经病学   2645篇
特种医学   710篇
外国民族医学   3篇
外科学   2386篇
综合类   5023篇
现状与发展   3篇
预防医学   2358篇
眼科学   208篇
药学   4290篇
  16篇
中国医学   1354篇
肿瘤学   1752篇
  2023年   441篇
  2022年   934篇
  2021年   1292篇
  2020年   1072篇
  2019年   1117篇
  2018年   1206篇
  2017年   1033篇
  2016年   1128篇
  2015年   1230篇
  2014年   2483篇
  2013年   2673篇
  2012年   2116篇
  2011年   2477篇
  2010年   1766篇
  2009年   1864篇
  2008年   1795篇
  2007年   1640篇
  2006年   1550篇
  2005年   1363篇
  2004年   1175篇
  2003年   954篇
  2002年   753篇
  2001年   731篇
  2000年   592篇
  1999年   549篇
  1998年   437篇
  1997年   367篇
  1996年   318篇
  1995年   346篇
  1994年   327篇
  1993年   365篇
  1992年   319篇
  1991年   269篇
  1990年   270篇
  1989年   215篇
  1988年   184篇
  1987年   147篇
  1986年   148篇
  1985年   227篇
  1984年   288篇
  1983年   123篇
  1982年   196篇
  1981年   140篇
  1980年   107篇
  1979年   97篇
  1978年   68篇
  1976年   66篇
  1975年   60篇
  1974年   63篇
  1973年   56篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Case reports The authors report their experience about three children (two girls, one boy; average age 1.6 years) with a spontaneous regression of optic gliomas. All of them had a previous diagnosis of neurofibromatosis type 1 (NF 1). None of them underwent surgery or biopsy nor received chemotherapy or radiotherapy. The complete regression was documented by MRI scans performed during a mean follow-up of 6.3 years.Literature review Moreover, the authors analyze the features of the 16 cases previously reported in English literature of spontaneously regressed optic gliomas with an overview of the different therapeutic strategies. The knowledge that this kind of tumor, particularly in young patients, may regress is important in the decision of the best therapeutic approach.  相似文献   
102.
【目的】探讨不稳定性心绞痛 (UA)病变程度及其预后与血浆肌钙蛋白I (cTnI)及C反应蛋白(CRP)水平的关系。【方法】测定 5 8例经选择性冠状动脉造影证实为冠心病的患者血浆cTnI及CRP浓度 ,并与对照组 (健康者 5 0例 )相比较 ,分析cTnI及CRP的临床意义。【结果】①血浆cTnI及CRP浓度在对照组、稳定性心绞痛组 (SA)、UA组分别为 :(0 4 2± 0 0 6 ) μg/L ,(2 2 93± 10 8) μg/L ;(0 5 9± 0 13) μg/L ,(5 2 16± 32 8) μg/L ;(1 92± 0 5 8) μg/L ,(13811± 86 1) μg/L ;SA组及UA组明显高于对照组 (分别为P <0 0 5 ,P<0 0 1)。②观察 4w ,在UA组心脏事件发生率为 35 5 % ,明显高于SA组 (P <0 0 5 )。③cTnI与CRP具有一定相关性 (r =0 5 1,P <0 0 5 )。【结论】血浆cTnI及CRP水平在临床评价UA病情程度及预后方面具有一定的指导意义  相似文献   
103.
医疗事故的定义、性质与类型新探   总被引:5,自引:1,他引:4  
文章在广泛比较借鉴国内外医疗事故方面的立法实例和学说理论的基础上,准确把握医疗事故的本质属性,揭示新旧立法中的医疗事故概念的缺陷和弊端,从学理上对它进行重新界定,并进而就医疗事故的性质、类型做出了精细的分析,应有助于相关法律立法质量的提高和司法中正确适用有关法律。  相似文献   
104.
2型糖尿病并脂肪肝与血脂紊乱的关系探讨   总被引:2,自引:0,他引:2  
目的 探讨 2型糖尿病并脂肪肝患者与脂代谢紊乱之间的关系。方法 对 60例 2型糖尿病并脂肪肝和 5 2例 2型糖尿病不并有脂肪肝病例的血脂谱 ,空腹血糖 (FPG ) ,餐后 2小时血糖 ( 2hPG) ,空腹胰岛素 (FINS)进行测定 ,计算体重指数 (BMI)及胰岛素敏感指数 (ISI)。结果  2型糖尿病并脂肪肝与不并脂肪肝相比 ,甘油三脂 (TG) ,低密度脂蛋白胆固醇 (LDL -C) ,FINS均升高 (P <0 .0 5 ,P <0 .0 1) ,而ISI明显降低 (P <0 .0 1)、脂蛋白a(Lp(a)降低(P <0 .0 5 )。结论  2型糖尿病并脂肪肝比不并脂肪肝者存在明显脂代谢紊乱及胰岛素抵抗  相似文献   
105.
1型糖尿病患者勃起功能障碍的患病情况及相关因素分析   总被引:2,自引:0,他引:2  
目的探讨1型糖尿病(T1DM)患者勃起功能障碍(ED)的患病情况及相关影响因素。方法收集182例已婚男性T1DM患者,用无记名问卷形式根据国际勃起功能指数问卷进行自我评分。并对年龄、病程、糖化血红蛋白(HbA1c)、睾酮、尿微量白蛋白排泄量、肾功能、血压、吸烟史、饮酒史、应用药物等因素进行调查,分析其与ED的关系。结果T1DM患者ED患病率为37.36%(68/182)。Logistic逐步回归分析结果显示,病程、年龄、HbA1c、收缩压、尿微量白蛋白排泄量与T1DM患者ED发生独立相关,病程增加5年、年龄增加10岁、HbA1c增加2%、收缩压增加4kPa及尿微量白蛋白排泄量的OR值分别为1.6275、1.1613、2.4211、2.3715、1.5234,P均〈0.01。结论加强对T1DM患者ED高危因素的关注和定期检测,有助于早期发现ED。  相似文献   
106.
107.
This study was to evaluate the effects of cigarette smoke constituents upon type II pneumocyte surfactant production in vitro, and how vitamins A and E may alter the response. Freshly isolated type II pneumocytes from Sprague–Dawley rats were incubated 20 h in medium with fetal bovine serum that was or was not treated with cigarette smoke. The number of adherent cells was inversely related to the dose of smoke or benzo(a)pyrene. Despite the decreased number of treated cells, the total amount of surfactant per culture well was unchanged, whereas surfactant production per cell was significantly increased (P < 0.05). Vitamin A concentration was significantly (P < 0.05) lower in the smoke-treated serum compared with untreated serum. When vitamin A or E was added to the cigarette smoke-treated serum, cell adherence and surfactant production returned to control values. In conclusion, cigarette smoke constituents or benzo(a)pyrene alone decreased the number of adherent type II pneumocytes, but did not alter surfactant amounts because of an increased production of surfactant per cell. Type II pneumocytes seem to adjust surfactant production dependent upon the number of type II pneumocytes to produce it and vitamin A or E enhance cell attachment in the presence of the smoke toxins.  相似文献   
108.
Summary To define the glucose to insulin dose-response relationship before the onset of diabetes, we studied 22 nondiabetic co-twins of patients with Type 1 (insulin-dependent) diabetes mellitus and nine control subjects. All had intravenous glucose tests at 0.02, 0.1 and 0.5 g/kg and were followedup prospectively for at least 6 years. Seven twins developed diabetes a mean of 7 months later; the remaining 15 are now unlikely to develop diabetes. The seven pre-diabetic twins had higher fasting insulin levels than control subjects (4.2±2.0 vs 1.8±1.8 nmol/l; p<0.05); but lower glucose clearance (1.0±0.5 vs 1.9±0.7 %/min; p<0.05), first phase insulin response at 0.5 g/kg (21.1±23.2 vs 143±50 nmol/l; p<0.0001), and total insulin responses at 0.1 g/kg (p<0.05) and 0.5 g/kg (p<0.00005). Using a curve-fitting programme, the normal glucose to insulin relationship was lost in prediabetic twins who had lower coefficient of determination (R2) than control subjects (p<0.01). In contrast, 15 low-risk twins and their nine control subjects had similar fasting glucose and insulin levels, glucose clearance, R2 and insulin secretory responses to different glucose loads. The positive predictive values of subnormal R2 and subnormal first phase insulin response were 67 % and 58 % respectively. These observations demonstrate an altered glucose to insulin dose-response relationship and loss of maximum insulin secretory response to glucose before the onset of Type 1 diabetes.  相似文献   
109.
Taurine has been proposed as an inhibitory neurotransmitter or neuromodulator in the vertebrate central nervous system. Within the spinal cord, taurine has been shown to have a direct inhibitory effect on spinal neurons and to have a selective antinociceptive effect on chemically induced nociception. Although sufficient data exists to suggest that taurine plays a neurotransmitter or neuromodulatory role in the spinal cord, it is not known whether this amino acid is present in axon terminals nor if this amino acid has a unique pattern of distribution within spinal tissue. To address these questions a monoclonal antibody against taurine was employed to localize taurine-like immunoreactivity in the dorsal horn of the rat spinal cord by using both light and electron microscopic techniques. Taurine-like immunoreactivity was most dense and most prominent in laminae I and II of the dorsal horn. A moderate amount of immunoreactivity was also present in laminae VIII and IX and X while the remaining laminae were only lightly stained. In laminae I and II taurine-like immunostaining was evident within neuronal cell bodies, dendrites, myelinated and unmyelinated axons, axon terminals, and astrocytes and their processes. Cell counts of these two laminae indicated that approximately 30% of neuronal perikarya at the C2 level, 52% of neuronal perikarya at the T6 level, and 18% of neuronal perikarya at the L2 level of the cord exhibited taurine-like immunoreactivity. With preembedding diaminobenzidine staining, approximately 20% of the axons examined in laminae I and II were found to be immunoreactive for taurine. Using postembedding immunogold staining in combination with quantitative procedures, the highest densities of gold particles were found in axon terminals containing pleomorphic vesicles and forming symmetrical synapses (36.8 particles/micron2), in a subpopulation of myelinated axons (34.2 particles/micron2), in a subpopulation of neuronal dendrites (32.6 particles/micron2), and in capillary endothelial cells (39.8 particles/micron2). Moderate labeling occurred in astrocytes (20.9 particles/micron2) and neuronal perikarya (18.7 particles/micron2). The localization of taurine to presumptive inhibitory axon terminals provides anatomical support for the hypothesis that taurine may serve an inhibitory neurotransmitter role in the superficial dorsal horn of the spinal cord. On the other hand, its localization to astrocytes and endothelial cells within both the dorsal ventral horns implies that it serves other nonneuronal functions as well.  相似文献   
110.
Summary In a nationwide incident case-referent study stepwise univariate analysis has revealed several risk determinants for childhood diabetes mellitus. In a multivariate analysis we have determined the set of risk determinants that would independently predict childhood Type 1 (insulin-dependent) diabetes. Possible interactions between the risk determinants and differences in risk profiles with different ages at onset were also examined. Reported familial insulin-treated and non-insulin-treated diabetes were significant risk factors in all age groups, as was also a low frequency of milk intake. The frequency of infections and a high intake of foods rich in nitrosamine tended to interact (OR 11.8, p=0.053) indicating a synergistic effect. A Cox regression analysis revealed that stressful life events during the last year was the only variable that tended to affect the age at onset (p=0.055). This indicated that psychological stress may rather precipitate than induce Type 1 diabetes. A short breast-feeding duration (OR=3.81), and an increased body height (OR=3.82) contributed significantly to the predictive model in only the youngest age group (0–4 years). An increased frequency of infections in the year preceding onset (OR=2.15) and no vaccination against measles (OR=3.33) contributed significantly to the model only in the age group 5–9 years. Various nutrients had different impacts on the risk of developing Type 1 diabetes in different age groups. It is concluded that in the genetically susceptible child, risk factors which are associated with eating habits, frequency of infections, vaccination status, growth pattern and severe psychological stress affect the risk of developing diabetes independently of each other. The set of risk determinants varies with the age at onset. A high frequency of infections and a high frequency of nitrosamine-rich food intake seem to have a synergistic effect on the risk of developing diabetes in childhood.  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