全文获取类型
收费全文 | 7723篇 |
免费 | 448篇 |
国内免费 | 77篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 224篇 |
妇产科学 | 107篇 |
基础医学 | 1057篇 |
口腔科学 | 953篇 |
临床医学 | 594篇 |
内科学 | 1655篇 |
皮肤病学 | 184篇 |
神经病学 | 452篇 |
特种医学 | 482篇 |
外科学 | 697篇 |
综合类 | 47篇 |
预防医学 | 815篇 |
眼科学 | 123篇 |
药学 | 496篇 |
中国医学 | 66篇 |
肿瘤学 | 221篇 |
出版年
2023年 | 71篇 |
2022年 | 172篇 |
2021年 | 241篇 |
2020年 | 195篇 |
2019年 | 232篇 |
2018年 | 317篇 |
2017年 | 183篇 |
2016年 | 206篇 |
2015年 | 257篇 |
2014年 | 323篇 |
2013年 | 409篇 |
2012年 | 555篇 |
2011年 | 630篇 |
2010年 | 316篇 |
2009年 | 316篇 |
2008年 | 383篇 |
2007年 | 459篇 |
2006年 | 333篇 |
2005年 | 271篇 |
2004年 | 205篇 |
2003年 | 160篇 |
2002年 | 175篇 |
2001年 | 136篇 |
2000年 | 124篇 |
1999年 | 124篇 |
1998年 | 98篇 |
1997年 | 96篇 |
1996年 | 115篇 |
1995年 | 74篇 |
1994年 | 80篇 |
1993年 | 65篇 |
1992年 | 59篇 |
1991年 | 64篇 |
1990年 | 52篇 |
1989年 | 80篇 |
1988年 | 67篇 |
1987年 | 72篇 |
1986年 | 80篇 |
1985年 | 65篇 |
1984年 | 36篇 |
1983年 | 36篇 |
1982年 | 32篇 |
1980年 | 21篇 |
1979年 | 23篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 26篇 |
1975年 | 28篇 |
1970年 | 21篇 |
1968年 | 20篇 |
排序方式: 共有8248条查询结果,搜索用时 15 毫秒
81.
A. Dolei C. Serra A. Biolchini S. Curreli P. Marongiu E. Gomes F. Ameglio 《Perspectives in Drug Discovery and Design》1996,5(1):93-102
Summary HIV-1 is a polytropic virus that, apart from hematopoietic cells, can replicate in several cells from solid tissues. Virus yields vary widely, closely resembling differences in HIV binding to the cells; the latter phenomenon appears mainly related to the extent of CD4 expression, even though other molecules have been implied in virus-cell interactions, the expression of which on the cell membrane can be modulated by several stimuli. During the course of HIV replication, a series of cytokines is produced and released in parallel to virus growth, particularly IL-6 and TNF-. In fact, exposure of fibroblasts or epithelial cells to these HIV-in-duced cytokines causes an increase of CD4 expression, HIV adsorption to uninfected cells, and release of infectious virions by infected cells. In cells exposed to interferon-, IL-6 and TNF- allow the virus to bypass interferon inhibition of virus release. The fact that HIV-1 adsorption and spread can be mediated by HIV-induced cytokines may be relevant in AIDS pathogenesis, accelerating virus transmission both within the organ and to infiltrating cells, activating a self-maintaining mechanism of infection. 相似文献
82.
C. Gomes T. H. Svensson G. Trolin 《Journal of neural transmission (Vienna, Austria : 1996)》1976,39(1-2):33-46
Summary Morphine caused in the anaesthetized rat reduction in brain noradrenaline (NA) turnover, hypotension and bradycardia, similarly to the antihypertensive,-adrenergic agonist, clonidine. All effects of morphine were antagonized by naloxone, as well as the-receptor antagonist, yohimbine. In contrast, naloxone did not affect the circulatory depression and reduction in brain NA utilization by clonidine, which both previously have been found to be antagonized by yohimbine. In contrast to clonidine, morphine even in high doses did not facilitate the flexor reflex activity of acutely spinalized rats. Pretreatment with protriptylin largely attenuated the circulatory depressive effects of morphine, as it has previously been found to block the corresponding effects of clonidine. Thus, the morphine-induced cardiovascular depressive effects are primarily elicited by activation of opiate receptors. However, the inhibition of brain NA neurotransmission by morphine appears critically involved in the mediation of the circulatory depression. 相似文献
83.
We are concerned in this paper with learning classification procedures from known cases. More precisely, we provide a diagnostic model that discriminate between cerebellum-pontine angle (CPA) tumors and otorhinolaryngological (ENT) disorders. Usually, in order to distinguish between CPA tumors and ENT disorders one must perform clinical-neurological examination together with expensive radiological imagery (CT and MRI). The proposed model was obtained through artificial intelligence methods and presented a good accuracy level (88.4%) when tested against new cases, considering only clinical examination without radiological imagery results. 相似文献
84.
85.
86.
The link between excessive consumption of dietary saturated fats and coronary heart disease (CHD) is now well established. Because of its high content of saturated fatty acids, the consumption of foods containing coconut oil may therefore be a risk factor for CHD. While the fatty acid composition of coconut oil is well established, relatively little is known about the other constituents of coconut: the milk, water, cream and meat fractions. In this study, we show that while the water fraction is low in lipid content, the milk contains about 24% of the fat content of oil and the cream and meat fractions about 34%. The other coconut constituents contain significant amounts of medium-chain triglycerides that are formed from fatty acids of chain length 8:0 to 14:0. It is these fatty acids, primarily 14:0, that are thought to be atherogenic. On the other hand, medium-chain triglycerides may be advantageous under some circumstances in that they are absorbed intact and do not undergo degradation and re-esterification processes. As a result, medium-chain triglycerides provide a ready source of energy and may be useful in baby foods or in diet therapy. Nevertheless, the possible negative effects of the saturated fatty acids and the absence of the essential fatty acid linolenic acid from all coconut constituents suggest that the coconut milk, oil and cream should not be used on a regular basis in adults. 相似文献
87.
JC VANCE DC CHANT DI TUDEHOPE PH GRAY AJ HAYES 《Journal of paediatrics and child health》1997,33(6):504-508
Objectives: To describe the physical growth patterns of infants born to narcotic dependent mothers (INDM) over a 12 months period and, if possible, to relate the growth to drug taking patterns during pregnancy.
Methodology: The growth of a cohort of 43 INDM was measured during the first 12 months of life. Weight and length measurements were compared with percentile charts and converted to Z scores. Questionnaire data about drug taking practices, demographic variables and the neonatal period (including withdrawal scores) were obtained.
Results: Twenty-four (55.8%) of INDM had evidence of neonatal drug withdrawal requiring treatment with phenobarbitone. At birth, Z scores for weight and length indicated relative intrauterine growth retardation. By 12 months, there had been some catch up growth, but Z scores for weight and length were still below zero. Persistent weight retardation at 12 months was correlated with methadone dosage during pregnancy, but not the need for phenobarbitone therapy.
Conclusions: The growth patterns of INDM in the first 12 months of life indicated that at birth there was evidence of intrauterine growth retardation, but by 12 months the growth was little different from the rest of the community. There appears to be some influence of narcotic agents taken while pregnant on subsequent growth of INDM. 相似文献
Methodology: The growth of a cohort of 43 INDM was measured during the first 12 months of life. Weight and length measurements were compared with percentile charts and converted to Z scores. Questionnaire data about drug taking practices, demographic variables and the neonatal period (including withdrawal scores) were obtained.
Results: Twenty-four (55.8%) of INDM had evidence of neonatal drug withdrawal requiring treatment with phenobarbitone. At birth, Z scores for weight and length indicated relative intrauterine growth retardation. By 12 months, there had been some catch up growth, but Z scores for weight and length were still below zero. Persistent weight retardation at 12 months was correlated with methadone dosage during pregnancy, but not the need for phenobarbitone therapy.
Conclusions: The growth patterns of INDM in the first 12 months of life indicated that at birth there was evidence of intrauterine growth retardation, but by 12 months the growth was little different from the rest of the community. There appears to be some influence of narcotic agents taken while pregnant on subsequent growth of INDM. 相似文献
88.
JC Labarthe 《Archives of disease in childhood》1997,77(2):140-144
This study was designed to look at the differences in visuospatial abilities between boys and girls before they can speak fluently. At the mandatory two year follow up visit, children were given the opportunity to build a tower and a bridge. In children whose birth weight was > or = 2500 g, the capacity for erecting a tower was the same in both sexes, but for building a bridge striking differences were noted according to their sex. Among the 376 children of this category, 41 out of 199 boys (21%) were able to build a bridge in comparison with 15 out of 177 girls (8%). This difference is highly significant. In children whose birth weight was < or = 2500 g, no differences were noted either for building a tower or a bridge. By showing that boys outnumber girls among the most skilled toddlers in spatial abilities, this work confirmed the action of a male related factor on cerebral lateralisation. 相似文献
89.
P de Lonlay-Debeney JC Fournet D Martin F Poggi C Dionisi Vicci M Spada G Touati J Rahier F Brunelle C Junien JJ Robert C Nihoul-Fékété JM Saudubray 《Archives de pédiatrie》1998,5(12):1347-1352
Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus. 相似文献
90.