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   1264284篇
  免费   94835篇
  国内免费   1580篇
耳鼻咽喉   16314篇
儿科学   41005篇
妇产科学   34951篇
基础医学   189468篇
口腔科学   34733篇
临床医学   117782篇
内科学   247880篇
皮肤病学   27280篇
神经病学   101869篇
特种医学   46818篇
外国民族医学   265篇
外科学   178688篇
综合类   25751篇
现状与发展   3篇
一般理论   568篇
预防医学   104694篇
眼科学   28049篇
药学   92573篇
  7篇
中国医学   2022篇
肿瘤学   69979篇
  2018年   13538篇
  2017年   10398篇
  2016年   11328篇
  2015年   13086篇
  2014年   18010篇
  2013年   27502篇
  2012年   37600篇
  2011年   40001篇
  2010年   23076篇
  2009年   22261篇
  2008年   37772篇
  2007年   40402篇
  2006年   39980篇
  2005年   39116篇
  2004年   37564篇
  2003年   35971篇
  2002年   34890篇
  2001年   56049篇
  2000年   57066篇
  1999年   48110篇
  1998年   13399篇
  1997年   12227篇
  1996年   12646篇
  1995年   11916篇
  1994年   11108篇
  1993年   10401篇
  1992年   38212篇
  1991年   37681篇
  1990年   36453篇
  1989年   35264篇
  1988年   32700篇
  1987年   32031篇
  1986年   30530篇
  1985年   28788篇
  1984年   21942篇
  1983年   19193篇
  1982年   11364篇
  1981年   10321篇
  1979年   20946篇
  1978年   15395篇
  1977年   12791篇
  1976年   11846篇
  1975年   12812篇
  1974年   15589篇
  1973年   15363篇
  1972年   14513篇
  1971年   13554篇
  1970年   12788篇
  1969年   12069篇
  1968年   11230篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
E B Larson 《JAMA》1991,265(23):3125-3126
  相似文献   
992.
To test the value of intensive management of diabetes before and during early pregnancy, 84 women recruited prior to conception were compared with 110 women who were already pregnant referred at 6 to 30 weeks' gestation. All underwent daily measurement of fasting and postprandial capillary blood glucose levels. Mean blood glucose levels during embryogenesis and organogenesis were within 3.3 to 7.8 mmol/L in 50% of preconception subjects and exceeded 10 mmol/L in 6.5%. One major congenital anomaly occurred in 84 infants (1.2%) of women treated before conception compared with 12 anomalies in 110 infants (10.9%) of mothers in the postconception group. Transient symptomatic hypoglycemia occurred during embryogenesis in 60% of women in the preconception group, with a median frequency of 2.7 episodes per week, but was not associated with excess malformations. We conclude that education and intensive management for glycemic control of diabetic women before and during early pregnancy will prevent excess rates of congenital anomalies in their infants.  相似文献   
993.
994.
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   
995.
996.
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   
997.
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   
998.
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   
999.
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   
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