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   542191篇
  免费   28328篇
  国内免费   591篇
耳鼻咽喉   6742篇
儿科学   17298篇
妇产科学   12863篇
基础医学   94509篇
口腔科学   12587篇
临床医学   49499篇
内科学   97937篇
皮肤病学   12031篇
神经病学   35140篇
特种医学   20193篇
外国民族医学   55篇
外科学   79764篇
综合类   7830篇
现状与发展   2篇
一般理论   119篇
预防医学   39618篇
眼科学   12136篇
药学   42231篇
  1篇
中国医学   1161篇
肿瘤学   29394篇
  2021年   4108篇
  2019年   4098篇
  2018年   6007篇
  2017年   4292篇
  2016年   5079篇
  2015年   5623篇
  2014年   7486篇
  2013年   11004篇
  2012年   16206篇
  2011年   18075篇
  2010年   10352篇
  2009年   9166篇
  2008年   16327篇
  2007年   18123篇
  2006年   17609篇
  2005年   16866篇
  2004年   16556篇
  2003年   15911篇
  2002年   15381篇
  2001年   22712篇
  2000年   23231篇
  1999年   19180篇
  1998年   5379篇
  1997年   4458篇
  1996年   4499篇
  1995年   4230篇
  1992年   14547篇
  1991年   15910篇
  1990年   16080篇
  1989年   15743篇
  1988年   14421篇
  1987年   14299篇
  1986年   13290篇
  1985年   12791篇
  1984年   9498篇
  1983年   8072篇
  1982年   4246篇
  1979年   9006篇
  1978年   6434篇
  1977年   5204篇
  1976年   5538篇
  1975年   6655篇
  1974年   7453篇
  1973年   7210篇
  1972年   6632篇
  1971年   6342篇
  1970年   5917篇
  1969年   5501篇
  1968年   5193篇
  1967年   4649篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Trends in analgesic self-poisoning in West-Fife, 1971-1985   总被引:1,自引:0,他引:1  
All admissions for analgesic self-poisoning to a district poisons unit over a 15-year period have been reviewed. During this time overdose with analgesic drugs increased to represent almost half of all admissions for self-poisoning. The types of analgesics taken in overdose also changed significantly during the period of this review. Aspirin and Distalgesic poisoning declined in incidence and more cases of self-poisoning by paracetamol and non-steroidal anti-inflammatory agents were seen. The impact of these changes on the medical management and outcome of deliberate self-poisoning is analysed. The reasons behind the trends described in this paper are assessed and their implications for future prevention and treatment are discussed.  相似文献   
122.
123.
Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis.  相似文献   
124.
125.
The connective tissue of the knee is frequently injured by athletes, especially those involved in contact sports. It would be important in the prevention of injury as well as the strategy of physical fitness training to know whether the connective tissue is modified in response to athletic stress or training. The potential modification investigated was variability in the concentration of hydroxyproline, a post-translationally modified imino acid found principally in collagen protein. A correlation was sought between this variability and the leg strength parameters torque (expressed as ft-lbs), torque/body weight and work (expressed as ft-lbs). In a preliminary study of five subjects, no correlation was found between hydroxyproline concentration of the patellar tendon and any of the leg strength parameters. These results suggest that this modification of the collagen in connective tissue does not occur in response to athletic stress or training, but rather, for the small number of subjects investigated, appeared to be relatively constant across a range of leg strengths.  相似文献   
126.
This study was undertaken to assess the role of the hypothalamus and medulla oblongata in regulation of liver circulation in anesthetized dogs. Blood pressure, flow in hepatic artery and portal vein, and shifts of blood volume in the liver were recorded. Stimulation of the anterior hypothalamus produced changes in arterial pressure which were followed by passive changes in hepatic arterial blood flow; changes in hepatic artery resistance were rather small. Stimulation of the medial and posterior hypothalamus increased hepatic arterial resistance by 65-170%. Liver portal blood flow during stimulation of most of the hypothalamic sites decreased, hepatic portal pressure rose and vascular portal venous resistance increased 2.5-3 times. Three areas only (sympatho-inhibitory area, paraventricular and lateral hypothalamic nuclei) when stimulated produced dilatation of hepatic portal and splanchnic vascular beds, thus increasing portal blood flow. All cases of stimulation led to the decrease of blood volume in the liver by 10-36%. Stimulation of medullary structures (n. tractus solitarii, reticular nn.) caused similar changes in hepatic circulation, however the amplitude of reaction was 1.5-6 times smaller than upon hypothalamic stimulation. Central impulses to the hepatic vessels are transmitted by sympathetic adrenergic nerve fibers through vascular alpha-adrenoreceptors. It is concluded that the hypothalamic level of the central nervous system, unlike the bulbar one, exerts considerable, differentiated, well coordinated and to some extent specific influences on hepatic circulation.  相似文献   
127.
V DeBack 《Nursing outlook》1991,39(3):124-127
On May 1, 1991, the National Commission on Nursing Implementation Project officially concluded. Its legacy is one of interdisciplinary collaboration and continuing work to redesign nursing education, practice, and research systems.  相似文献   
128.
Intracranial venous thrombosis has been described in newborns, but there have been no reports of intractable neonatal seizures due to this condition. We report cortical venous sinus thrombosis in two term neonates who presented with seizures in the first 24 hours of life. The diagnosis was made by cranial computed tomography and was confirmed by cerebral angiography. Both patients improved clinically after the intracranial venous thrombosis resolved. These patients demonstrate that intracranial venous thrombosis should be considered in the differential diagnosis of neonatal seizures.  相似文献   
129.
We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries.  相似文献   
130.
V Váradi  L Karmazsin 《Orvosi hetilap》1989,130(24):1251-1255
Prenatal, intrapartum and postnatal factors were investigated in less than 32 gestational age preterm infants known to have periventricular haemorrhage or periventricular leukomalacia. The diagnoses were established on cranial ultrasonography and/or autopsy. Factors associated with periventricular haemorrhage were: postnatal severe hypercapnia, acidosis and hypoxia. In the periventricular leukomalacia group the incidence of antepartum and intrapartum hypoxia and/or ischaemia (antepartum haemorrhage) were significantly higher than in the control group.  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