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   25292篇
  免费   3204篇
  国内免费   557篇
耳鼻咽喉   300篇
儿科学   349篇
妇产科学   347篇
基础医学   1309篇
口腔科学   9532篇
临床医学   1442篇
内科学   1919篇
皮肤病学   495篇
神经病学   317篇
特种医学   226篇
外国民族医学   1篇
外科学   1124篇
综合类   1974篇
现状与发展   3篇
预防医学   1317篇
眼科学   67篇
药学   5327篇
  28篇
中国医学   1515篇
肿瘤学   1461篇
  2024年   65篇
  2023年   524篇
  2022年   708篇
  2021年   1017篇
  2020年   1213篇
  2019年   1256篇
  2018年   1174篇
  2017年   1112篇
  2016年   1095篇
  2015年   1047篇
  2014年   1416篇
  2013年   2080篇
  2012年   1279篇
  2011年   1354篇
  2010年   1020篇
  2009年   980篇
  2008年   989篇
  2007年   972篇
  2006年   903篇
  2005年   909篇
  2004年   788篇
  2003年   728篇
  2002年   677篇
  2001年   605篇
  2000年   534篇
  1999年   453篇
  1998年   413篇
  1997年   434篇
  1996年   345篇
  1995年   309篇
  1994年   281篇
  1993年   226篇
  1992年   240篇
  1991年   187篇
  1990年   178篇
  1989年   184篇
  1988年   144篇
  1987年   134篇
  1986年   126篇
  1985年   115篇
  1984年   109篇
  1983年   71篇
  1982年   107篇
  1981年   108篇
  1980年   77篇
  1979年   60篇
  1978年   49篇
  1977年   75篇
  1976年   59篇
  1975年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Background: It has been suggested that oral cobalamin (vitamin B12) therapy may be an effective therapy for treating cobalamin deficiencies related to food‐cobalamin malabsorption. However, the duration of this treatment was not determined. Patients and method: In an open‐label, nonplacebo study, we studied 30 patients with established cobalamin deficiency related to food‐cobalamin malabsorption, who received between 250 and 1000 μg of oral crystalline cyanocobalamin per day for at least 1 month. Endpoints: Blood counts, serum cobalamin and homocysteine levels were determined at baseline and during the first month of treatment. Results: During the first month of treatment, 87% of the patients normalized their serum cobalamin levels; 100% increased their serum cobalamin levels (mean increase, +167 pg/dl; P < 0.001 compared with baseline); 100% had evidence of medullary regeneration; 100% corrected their initial macrocytosis; and 54% corrected their anemia. All patients had increased hemoglobin levels (mean increase, +0.6 g/dl) and reticulocyte counts (mean increase, +35 × 106/l) and decreased erythrocyte cell volume (mean decrease, 3 fl; all P < 0.05). Conclusion: Our findings suggest that crystalline cyanocobalamin, 250–1000 μg /day, given orally for 1 month, may be an effective treatment for cobalamin deficiencies not related to pernicious anemia.  相似文献   
102.
目的 通过健康受试者的双交叉试验比较萘普生缓释胶囊与普通片的药物动力学和生物利用度。方法10位健康受试者一次服用这两种制剂500mg,在稳态试验中8位受试者接受两种制剂5天,缓释胶囊500mg每天一次,普通片每天两次,每次250mg。血药浓度用HPLC方法测定。结果 一次服药试验证明该缓释胶囊血药浓度上升缓慢,浓度变化平稳,Gmax为85.9μg/ml,Tpeak为6.0h,而普通片的Cmax为140.4μg/ml,Tpeak为3.2h,两种制剂的生物利用度相当,缓释胶囊与普通片生物等效。通过8位健康受试者交叉连续服用萘普生缓释胶囊与普通片的稳态药代动力学研究表明,到第3天给药后已达到稳态,由第5天给药后的血药浓度测定数据计算其主要的稳态药代动力学参数,缓释胶囊的峰浓度(Cmax)、峰谷比和波动度(DF)明显低于普通片,这些参数分别为73,1μg/ml、1.48和37.7o;而普通片的上述参数分别为 100.8μg/ml、2.51和78.2%。结论 奈普生缓释胶囊具有缓释作用,能较好维持血药治疗浓度。  相似文献   
103.
The objective of the present study was to assess possible adaptive functional changes in the masticatory system after insertion of fixed prostheses supported by osseointegrated implants in the edentulous mandible. Registrations of mandibular movement characteristics and maximal biteforce were performed at insertion and after 1 week, 3 months and 1 year after connection. The duration of the opening and closing phase decreased and maximal biteforce increased significantly (p < or = 0.05-0.001) from connection of the prostheses to the annual check-up. However, the process of functional adaptation implied 2 identified stages. An immediate phase that occurred within the 1st week, probably due to altered impact from mechano-sensitive receptors and a later more time-dependent phase, based on learning and new cortical engrams. Accordingly, the process of adaptation will continue over a long period of time.  相似文献   
104.
105.
目的:观察第二、三代口服避孕药(COC)对育龄妇女体重指数、血压、血糖和血脂的影响。方法:将自愿服用COC避孕1年的妇女105例随机分为两组,其中54例给予第二代COC(EE/LNG组),51例给予第三代COC(EE/DG组)。并对研究前后所有病例的体重指数(BMI)、血压、血糖和血脂代谢指标进行比较分析。结果:EE/LNG组:BMI、收缩压、舒张压、甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白(LDL)和载脂蛋白B(ApoB)水平均升高,高密度脂蛋白(HDL)水平下降,血糖、载脂蛋白AI(ApoAI)水平无明显改变。EE/DG组收缩压、TG、HDL水平升高,BMI、舒张压、血糖、TC、LDL、ApoAI和ApoB均未发生显著变化。以上所有测量指标均未超出正常范围。结论:使用1年第二、三代COC对妇女BMI、血压和血脂代谢都有微弱的影响,对空腹血糖无明显影响。第三代COC对妇女BMI、收缩压、舒张压、TG、TC、LDL、HDL水平和ApoB的不利影响小于第二代,更加安全可靠。  相似文献   
106.
Histoplasmosis is a fungal disease that affects humans and is caused by Histoplasma capsulatum. The presentation of the infection may be acute, chronic, or disseminated. The disseminated form has extrapulmonary manifestations which may include oral manifestation a. A patient with AIDS sought treatment and he had disseminated histoplasmosis with oral manifestations. The purpose of this case report and literature review is to emphasize the role the dental team has in the diagnosis of disseminated disease when a patient presents with oral manifestations associated with the disease. This case report is clinically relevant because it is not uncommon for oral manifestations to be one of the first signs of systemic disease.  相似文献   
107.
Investigators have tried to identify a level of seric specific immunoglobulin E (IgE) that had a sufficient predictive value to diagnose a food allergy without having will resort to the food challenge. To search in literature, all the studies that have estimated the possibility to identify a level of seric specific cow milk IgE with a positive predictive value (PPV) of 95% for the first diagnosis of cow's milk allergy (CMA) in pediatric age. We have identified six studies, nearly all studies suffer from relevant methodological bias. Proposed cut-off are all different. The studied pediatric populations were highly selected. Also neglecting the methodological bias of the studies and the great difference of value between the proposed cut-off, it always remains to consider that the pre-test probability of having a CMA between the children enrolled in the six studies included in this review is particularly high. The likelihood ratio helps to transfer the results of a study on a diagnostic test just to our population, and it is more realistic rather than to entrust itself to the PPV or the negative predictive value, that are much influenced from the prevalence of the disease in the studied population.  相似文献   
108.
The mortality of cerebrovascular diseases in Denmark was analysed for men and women 15-44 years of age, in a 14-year period before and after the appearance of oral contraceptives (OC) in 1966. 1,670 deaths were registered over 28 years, during which the female incidence of cerebrovascular deaths increased by 19% (P less than 0.025), while the male mortality was unchanged. Women showed a percentage increase in deaths from cerebral thromboembolic attacks (CTA) of 33%, men a fall of 14%. The increase of female CTA deaths was most pronounced in the young fertile group, the age group with a high OC use. A relative risk of CTA of 3.3-4.5 for OC users compared with non-users could explain the CTA trend difference between women and men. No other single risk factor responsible for the observed trends could be identified. Both women and men had a significant increase in the mortality of subarachnoidal hemorrhages, and a significant fall in the mortality of intracerebral hemorrhages.  相似文献   
109.
目的 研究妊娠期糖尿病与胎儿生长发育中糖代谢特点的关系。方法 选择妊娠期糖尿病25例(GDM组),正常孕妇20例(对照组),分别测孕妇空腹血糖、糖耐量、C肽、IGF-I、新生儿出生2h内空腹血糖,并依据新生儿出生体重分为大于胎龄儿组(LGA组,≥4000g),适于胎龄儿组(AGA组,2500-3999g)。结果 C肽及新生儿出生2h内空腹血糖GDM组与对照组差异有显著性;糖耐量各时点血糖值餐后2h血糖值LGA和AGA组差异有显著性。结论 血糖始终是影响胎儿生长发育的重要因素,孕妇餐后2h血糖水平与巨大儿的发生呈正相关。  相似文献   
110.
法莫替丁冲剂在健康人中的生物利用度及药动学研究   总被引:1,自引:0,他引:1  
本实验采用反相高效液相色谱法,比较了10名健康志愿者单剂量口服法莫替丁冲剂及等剂量片剂的生物利用度。结果表明:二种剂型的Tmax,Cmax,AUC均无显著性差异(P〉0.05)。冲剂相对于与片剂的相对生物利用度F=101.90。  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