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   8037篇
  免费   419篇
  国内免费   119篇
耳鼻咽喉   17篇
儿科学   87篇
妇产科学   809篇
基础医学   676篇
口腔科学   28篇
临床医学   792篇
内科学   1504篇
皮肤病学   164篇
神经病学   415篇
特种医学   379篇
外科学   636篇
综合类   972篇
现状与发展   1篇
一般理论   2篇
预防医学   1276篇
眼科学   26篇
药学   459篇
  3篇
中国医学   206篇
肿瘤学   123篇
  2024年   16篇
  2023年   123篇
  2022年   276篇
  2021年   368篇
  2020年   361篇
  2019年   320篇
  2018年   342篇
  2017年   291篇
  2016年   318篇
  2015年   283篇
  2014年   572篇
  2013年   574篇
  2012年   445篇
  2011年   529篇
  2010年   432篇
  2009年   413篇
  2008年   401篇
  2007年   385篇
  2006年   293篇
  2005年   252篇
  2004年   221篇
  2003年   192篇
  2002年   149篇
  2001年   147篇
  2000年   126篇
  1999年   72篇
  1998年   62篇
  1997年   75篇
  1996年   47篇
  1995年   61篇
  1994年   53篇
  1993年   36篇
  1992年   37篇
  1991年   28篇
  1990年   25篇
  1989年   18篇
  1988年   15篇
  1987年   16篇
  1986年   18篇
  1985年   22篇
  1984年   21篇
  1983年   15篇
  1982年   17篇
  1981年   22篇
  1980年   15篇
  1979年   11篇
  1978年   10篇
  1977年   7篇
  1976年   10篇
  1973年   14篇
排序方式: 共有8575条查询结果,搜索用时 180 毫秒
31.
Fractional flow reserve (FFR) is a well-validated index for assessing the physiologic significance of a coronary stenosis in most clinical conditions encountered in today's catheterisation laboratory. The aim of this paper is to provide a short overview of the theoretical background of the coronary pressure-derived FFR index and its clinical applicability in guiding complex coronary intervention procedures.  相似文献   
32.
目的总结用人工合成材料的吊带经不同的途径治疗女性压力性尿失禁的方法和结果。方法采用人工合成材料的吊带经耻骨固定(In—Fast)技术治疗3例,用经腹壁固定(TVT和IVS)技术治疗13例。结果绝大多数病人均排尿通畅.无尿失禁复发。但TVT组有1例排尿不畅,3个月后剪断吊带后变为轻度尿失禁。In-fast组有1例性交不适伴阴道分泌物增加。结论用人工合成材料的吊带进行悬吊技术治疗女性真性压力性尿失禁是安全、微创和有效的手术方式。经耻骨固定技术和用经腹壁固定技术这两种方法各有自己的优缺点。应根据病人的具体情况去选择使用。  相似文献   
33.
The acute effects of protein loading (1.5 g kg-1) on glomerular filtration rate (GFR) and urinary albumin excretion (UAE) were investigated in 23 type-I diabetic patients with no clinical nephropathy, and in 7 healthy subjects (controls). The results were compared with renal morphology data. In controls and in 14 diabetic patients (group 1) GFR increased by 27 and 37%, respectively, corresponding to normal renal reserve, but in 9 patients (group 2) GFR decreased by 20%, indicating the absence of a renal reserve. Microalbuminuria was found in none of the patients in group 1 and in 50% of patients in group 2. Two hours after the load UAE increased in all groups, but the increase was most marked in group 2, despite the fall in GFR. The two groups of patients did not differ with regard to the duration and control of diabetes, but differed markedly in terms of baseline GFR (131 vs. 195 ml min-1, P less than 0.01, in groups 1 and 2, respectively). Renal morphology showed minimal non-specific glomerular injury in group 1, and signs of glomerulosclerosis in group 2. We conclude that the impaired renal response to protein load precedes other subclinical manifestations of diabetic renal injury, and may be useful in the diagnosis of latent diabetic nephropathy.  相似文献   
34.
军队官兵演习后期的心理变化   总被引:2,自引:1,他引:1  
为探讨军队官兵在演习后期的心理变化,本分析了军队官兵在演习后期存在放松心理,思乡情绪,自我肯定以及发泄心理等的原因,并提出了相关对策;为稳定演习官兵的思想情绪提供参考。  相似文献   
35.
羊膜建库及其临床应用研究   总被引:3,自引:0,他引:3  
目的 :制备与保存羊膜 (Amnioticmembrane,AM ) ,为临床移植治疗眼表泪液 (Ocularsur face&Teardisease ,OSTD)提供新鲜羊膜 (Freshamnioticmembrane ,FSAM )、冻干羊膜 (Frozenam nioticmembrane ,FZAM )并观察其眼表重建的特点与临床疗效。方法 :采用目前国际公认的羊膜制备与保存方法 ,制备FSAM、FZAM并进行保存研究 ,经组织染色和电子显微镜检查 ,观察保存羊膜的形态及其活性 ;并将FSAM、FZAM应用于 12例OSTD患者 ,行患眼FSAM或FZAM移植术。通过术后印迹细胞学追踪观察移植后AM上皮细胞存活与移行、替代时间 ,评估AM移植重建眼表的临床疗效。结果 :FSAM、FZAM在光镜和电镜下均与正常球结膜组织结构相近 ,主要结构为胶原纤维和网状纤维。 12例OSTD患者行羊膜移植术 (Amnioticmembranetransplantation ,AMT)后均未见明显急性排斥反应 ,术后 1~ 2周可见少量新生血管长入植片 ,AMT后印迹细胞学追踪检查 ,术后 3个月为阴性 ,4个月出现阳性反应。所有患者术后随访 5~ 18个月 ,平均 11个月 ,AM在术后 4~ 9个月逐渐溶解、消失 ,移植区眼表的色泽与结构基本恢复正常。结论 :FSAM、FZAM是目前理想的结膜替代材料并可有效地用于重建角、结膜表面 ,减轻炎症反应 ,减少新生血管的生成 ,抑制纤维组织增生 ,防止  相似文献   
36.
Nasopharyngeal angiofibromas occur predominantly in males in their puberty and adolescence; the incidence in other age groups and in women is exceptional. This report describes a case of a 57-year-old woman with nasopharyngeal angiofibroma presenting typical radiological findings in computed tomography, MR imaging and angiography. The tumour was successfully removed and histopathological examination confirmed the diagnosis. In 6 years follow-up the patient is free of symptoms.  相似文献   
37.
Gender differences after acute cocaine administration have received little attention in spite of the fact that males and females respond differently to many drugs. Seven male and seven female occasional cocaine users received both an intranasal dose of cocaine hydrochloride (0.9 mg/kg) and placebo powder in a randomized order and reported subjective effects via an instrumental joystick device and various questionnaires. Blood samples were withdrawn at 5-min intervals to assess pharmacokinetic differences. Male subjects achieved the highest peak plasma cocaine levels (144.4 ± 17.5 ng/ml), detected cocaine effects significantly faster than females and also experienced a greater number of episodes of intense good and bad effects. Women studied during the follicular phase of their menstrual cycle had peak plasma cocaine levels of 73.2 ± 9.9 ng/ml, which was significantly higher than when they were studied during their luteal phase (54.7 ± 8.7 ng/ml), but there were no differences in their subjective reports of cocaine effects. In spite of the different cocaine blood levels and subjective effects, peak heart rate increases did not differ between males and females suggesting that women may be more sensitive than males to the cardiovascular effects of cocaine. These data suggest that there are significant gender and menstrual cycle differences in the response to acute intranasal cocaine administration and these differences may have implications for the differential abuse of this drug.This paper is dedicated to Xavier Lamas, MD, PhD, who lost his life while ascending Mt. Everest, August 1995  相似文献   
38.
Reproduction stops among the majority of prairie voles (Microtus ochrogaster) during the winter. Short day lengths suppress male reproductive function dramatically in the laboratory, but photoperiod exerts only subtle effects on female reproductive function. Thus, the regulation of seasonal breeding in this species remains partially unspecified. In contrast to commonly studied rodents, female prairie voles do not undergo spontaneous estrous cycles; rather, they are induced into estrus by exposure to chemosignals expressed in conspecific male urine. In the present study, the hypothesis was tested that seasonal breeding among female prairie voles in the field reflects photoperiod-mediated changes in the responsiveness of the chemosensory system to male urine. Responsiveness was assessed by localizing the product of the c-fos immediate early gene with an immunocytochemical procedure. Female prairie voles were maintained in either long (LD 16:8) or short (LD 8:16) photoperiods from birth until adulthood, and exposed to either male urine or skim milk. Immunocytochemistry forfos protein revealed an increased number of immunoreactive cells within the accessory olfactory system of female prairie voles, including the accessory olfactory bulbs, granule cell layer, as well as the medial and cortical divisions of the amygdala 1 h after exposure to a single drop of urine as compared to individuals exposed to skim milk. The number of immunoreactivefos cells induced in females by conspecific male urine was also affected by photoperiod; short day females displayed fewer immunoreactivefos neurons in the accessory olfactory system as compared to long-day animal. Taken together, these results indicate that similar mechanisms underlie the responses of different rodent species to the chemosignals of conspecifics and that the pattern offos expression observed in the present study has functional significance for the regulation of reproduction in prairie voles.  相似文献   
39.
采用逐级负荷踏车实验和阻抗心动图的方法,测定居住3417m高原13~16岁藏汉族青少年静息状态下,运动后即刻及恢复期心率和左心收缩间期,结果显示,静息状态下两组STI各数值无差异,藏族运动后即刻的PEP短于汉族,LVET长于汉族,P/L有明显差异(P<0.01),经心率矫正后藏族运动后即刻LVETI及QS_2I均长于汉族,恢复期短于汉族,形成交叉曲线,说明居住高原的汉藏族人群的心功能差别在青少年时已经出现。提示:藏族在运动状态下有良好的心力储备及对运动负荷的适应能力,其原因可能与生长发育的环境及种群遗传有关。  相似文献   
40.
Summary Ninety-one percent (n=182) of the female members of South Australian representative squads in 14 sports volunteered to act as subjects. Twenty-seven percent of them had represented Australia. The underwater weighing method together with the measurement of residual volume (RV) by helium dilution were used to determine body density (BD); the percent body fat (% BF) was then computed according to Siri.A stepwise multiple regression analysis yielded a correlation coefficient (R) of 0.863 between the criterion (BD) and the best weighted sum of predictors (anthropometric variables): BD (g·cm–3)=1.14075–0.04959 (log10 triceps, subscapular, supraspinale and calf skinfolds in mm)+0.00044 (age in decimal years)–0.000612 (waist girth in cm)+0.000284 (height in cm)–0.000505 (gluteal girth in cm)+0.000331 (breast girth in cm).Only those predictors which resulted in a statistically significant increase inR (p0.05) were included. The standard error of estimate of 0.00597 g · cm–3 was equivalent to 2.7% BF at the mean. This equation was shown to be largely population specific. There was a range of 7.6–35.8% of BF and the overall mean of 18.5% was significantly lower (p<0.001) than that of 23.4% obtained on a moderately active reference sample of similar age (n=135). If group sizes of only one or two are regarded as too small for meaningful comparison, then the lowest mean of 13.5% was achieved by the long-distance runners (n=14). The highest averages were registered by the heavyweight rowers (24.2%;n=7) and soccer players (22.0%;n=11). The overall average for games players (n=107) was 19.4%.This study was supported by a grant from the National Health and Medical Research Council of Australia  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