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   1265811篇
  免费   94917篇
  国内免费   1584篇
耳鼻咽喉   16451篇
儿科学   41022篇
妇产科学   34962篇
基础医学   189623篇
口腔科学   34755篇
临床医学   118077篇
内科学   248055篇
皮肤病学   27300篇
神经病学   102004篇
特种医学   46838篇
外国民族医学   265篇
外科学   178826篇
综合类   25781篇
现状与发展   3篇
一般理论   571篇
预防医学   104990篇
眼科学   28058篇
药学   92633篇
  8篇
中国医学   2022篇
肿瘤学   70068篇
  2018年   13547篇
  2017年   10402篇
  2016年   11335篇
  2015年   13091篇
  2014年   18026篇
  2013年   27516篇
  2012年   37680篇
  2011年   40075篇
  2010年   23092篇
  2009年   22282篇
  2008年   37828篇
  2007年   40469篇
  2006年   40040篇
  2005年   39163篇
  2004年   37608篇
  2003年   36024篇
  2002年   34940篇
  2001年   56086篇
  2000年   57102篇
  1999年   48140篇
  1998年   13420篇
  1997年   12297篇
  1996年   12683篇
  1995年   11931篇
  1994年   11132篇
  1993年   10417篇
  1992年   38257篇
  1991年   37722篇
  1990年   36503篇
  1989年   35320篇
  1988年   32733篇
  1987年   32066篇
  1986年   30571篇
  1985年   28838篇
  1984年   21962篇
  1983年   19211篇
  1982年   11377篇
  1981年   10334篇
  1979年   20968篇
  1978年   15408篇
  1977年   12809篇
  1976年   11860篇
  1975年   12827篇
  1974年   15611篇
  1973年   15383篇
  1972年   14531篇
  1971年   13563篇
  1970年   12800篇
  1969年   12074篇
  1968年   11241篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Nuclear magnetic resonance (NMR) spectroscopy has been reported as an alternative method for quantitating deuterium oxide concentrations in the evaluation of total-body-water in humans. However, the presence of dissolved plasma proteins results in an underestimation of deuterium NMR (2H-NMR) intensity ratios, thereby causing an overestimation (5-6%) of total-body-water (TBW) values determined from nonsublimed patient plasma samples. We demonstrate that plasma samples must be corrected for the volume percentage of water in plasma. Correction of initial 2H-NMR intensity ratios with a factor of 0.93 results in intensity ratios comparable to those determined from plasma samples subjected to vacuum sublimation to remove all plasma solutes.  相似文献   
993.
994.
Electronystagmography (ENG) was performed on 127 dizzy patients and the findings were compared with the diagnosis obtained with a comprehensive neurological test battery. ENG was found to be abnormal in 49 (39%) of the patients: 19 with unilateral vestibular hyporeactivity, eight with directional preponderance, 12 with spontaneous or undirectional positional nystagmus, eight with abnormal smooth pursuit, and 13 with other abnormalities. Among the patients with abnormal ENGs, established central nervous system lesions were found in 28 cases (19 of these infratentorial lesions); nine peripheral vestibular lesions and five undefined vestibular lesions were found. Patients with normal ENGs showed fewer peripheral vestibular lesions and more dizziness of psychogenic aetiology. Almost half the patients with infratentorial lesions had normal ENGs. Patients with rotatory vertigo had fewer ENG abnormalities than those with other types of dizziness. These results suggest that ENG alone is of limited value in the diagnosis of dizziness. A comprehensive test battery is needed to establish the diagnosis.  相似文献   
995.
The paper reviews existing reports on relations between pathologies leading to malabsorption and dental lesion in children. The following dental alterations are reported in the literature: delayed eruption of deciduous teeth, hypoplasia of enamel and dental caries. These lesions have been observed in gastrointestinal pathologies, for example, coeliac disease, chronic diarrhea and recurrent vomiting, intolerance of cow's milk protein, Crohn's disease and salmonellosis. The delayed eruption of deciduous teeth and hypoplasia of the enamel are certainly correlated to malabsorption and maldigestion, especially if these are protracted over time. Dental caries may be due to poor oral hygiene, poor diet and to the presence of modified calcification. Only a comparative study with a control group will enable the effective prevalence to be assessed.  相似文献   
996.
Taurine in pediatric nutrition: review and update   总被引:2,自引:0,他引:2  
G E Gaull 《Pediatrics》1989,83(3):433-442
Taurine was long considered an end product of the metabolism of the sulfur-containing amino acids, methionine and cyst(e)ine. Its only clearly recognized biochemical role had been as a substrate in the conjugation of bile acids. Taurine is found free in millimolar concentrations in animal tissues, particularly those that are excitable, rich in membranes, and generate oxidants. Various lines of evidence suggest one major nutritional role as protecting cell membranes by attenuating toxic substances and/or by acting as an osmoregulator. The totality of evidence suggests that taurine is nonessential in the rodent, it is an essential amino acid in the cat, and it is conditionally essential in man and monkey. Absence from the diet of a conditionally essential nutrient does not produce immediate deficiency disease but, in the long term, can cause problems. Taurine is now added to many infant formulas as a measure of prudence to provide improved nourishment with the same margin of safety for its newly identified physiologic functions as that found in human milk. Such supplementation can be justified by the finding of improved fat absorption in preterm infants and in children with cystic fibrosis, as well as by salutary effects on auditory brainstem-evoked responses in preterm infants. Experimental findings in animal models and in human cell models provide further justification for taurine supplementation of infant formulas.  相似文献   
997.
Idiopathic retroperitoneal fibrosis. A retrospective analysis of 60 cases   总被引:5,自引:0,他引:5  
Sixty patients with idiopathic retroperitoneal fibrosis presenting between 1965 and 1984 are reviewed. Their mean age at presentation was 56 years and the male:female ratio was 3:1. The commonest presenting symptoms were flank and abdominal pain, weight loss, nausea and polyuria. Physical examination was usually normal, expect for the presence of hypertension. Anaemia and elevation of erythrocyte sedimentation rate were usually present. Proteinuria was found in less than a third of patients at presentation and significant bacteriuria was uncommon. The correct diagnosis was made or suspected in very few patients before referral. The cumulative actuarial survival rate was 86% at 1 year and 78% at 2 years. Seventeen patients died; they were significantly older and more uraemic at the time of referral than those who survived. A few patients did well with either corticosteroid therapy or ureterolysis alone. In the majority, both operation and steroid treatment were necessary. In bilateral obstruction with residual function in both kidneys, bilateral ureterolysis proved superior to unilateral operation (each followed by steroid therapy) in conserving renal function. Operation alone or steroid therapy alone should be considered in cases where steroids or surgery respectively present particular hazards. The less traumatic unilateral operation should be considered in poor risk patients and in those whose renal function is absent on one side. In many survivors, disease activity has persisted for many years. Life-long follow-up is recommended.  相似文献   
998.
999.
1000.
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