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   1253996篇
  免费   97636篇
  国内免费   27683篇
耳鼻咽喉   15269篇
儿科学   33357篇
妇产科学   30246篇
基础医学   165617篇
口腔科学   30634篇
临床医学   124900篇
内科学   228450篇
皮肤病学   22943篇
神经病学   88464篇
特种医学   49864篇
外国民族医学   560篇
外科学   173200篇
综合类   88158篇
现状与发展   86篇
一般理论   278篇
预防医学   90313篇
眼科学   30493篇
药学   103243篇
  421篇
中国医学   25986篇
肿瘤学   76833篇
  2022年   9690篇
  2021年   22863篇
  2020年   17786篇
  2019年   17881篇
  2018年   20970篇
  2017年   18652篇
  2016年   18202篇
  2015年   25309篇
  2014年   33004篇
  2013年   37938篇
  2012年   53526篇
  2011年   58682篇
  2010年   37779篇
  2009年   33040篇
  2008年   47119篇
  2007年   48412篇
  2006年   47647篇
  2005年   46335篇
  2004年   38704篇
  2003年   37434篇
  2002年   34833篇
  2001年   49385篇
  2000年   50403篇
  1999年   44229篇
  1998年   15106篇
  1997年   14113篇
  1996年   12264篇
  1995年   12052篇
  1994年   11132篇
  1993年   9530篇
  1992年   30423篇
  1991年   28961篇
  1990年   28070篇
  1989年   26775篇
  1988年   24707篇
  1987年   24169篇
  1986年   23073篇
  1985年   21750篇
  1984年   16107篇
  1983年   13680篇
  1982年   8163篇
  1979年   14698篇
  1978年   10238篇
  1977年   8645篇
  1975年   8960篇
  1974年   10714篇
  1973年   10197篇
  1972年   9690篇
  1971年   8928篇
  1970年   8593篇
排序方式: 共有10000条查询结果,搜索用时 498 毫秒
991.
Biliary atresia is the most common indication for orthotopic liver transplantation (OLT) in children. The polysplenia syndrome anomalies, which occur in approximately 10% of children with biliary atresia, may represent special difficulties at liver transplantation. We have reviewed our experience with this syndrome in 116 children with biliary atresia who underwent liver transplantation between March 1984 and December 1989. The main features of the polysplenia syndrome, which included absence of the inferior vena cava, preduodenal portal vein, midgut malrotation, aberrant hepatic artery, and situs inversus, were encountered in 12 of the 116 children (10.3%). Severe portal vein hypoplasia (3.5 mm or smaller) was also present in 7 of these children. Eight patients received a complete and four received a reduced liver graft. The vascular anomalies increased the technical difficulty of OLT but could be surmounted, although they did contribute to the peroperative death of one child. The 1-month survival rate was 83% for the 12 children with features of the polysplenia syndrome and 88% for the other 92 children with biliary atresia alone.  相似文献   
992.
With topical therapy using dinitrochlorobenzene (DNCB), 36 (72%) out of 50 patients having alopecia areata showed regrowth of hair in 3 to 6 months time. Five (10%) patients experienced marked vesiculation and severe contact dermatitis requiring cessation of therapy. In 7 (14%) patients there was no response at all and 4 (8%) presented with other side-effects.  相似文献   
993.
Existing triage algorithms consider, for the most part, only the primary casualty with physical trauma. Algorithms fail to appreciate the primary, secondary, or tertiary neuropsychiatric casualty. Research advances on neuropsychiatric casualties must link with the mandates of emergency medical services and disaster management to improve triage sensitivity and specificity. Early recognition and management of neuropsychiatric casualties will diminish the potential for long-term consequences. Expanded triage algorithm supplements are proposed to improve the recognition of those victims at risk.  相似文献   
994.
Plasma viscosity, molecular markers of activated coagulation and fibrinolysis (fibrinopeptides A and B beta 15-42), coagulation factors (fibrinogen and factor VII) and antiplasmins were measured in 529 men aged 35-54 years and related to new angina pectoris (n = 117) and to coronary risk factors in controls without angina (n = 412). Five major risk factors (cigarette-smoking, blood pressure, cholesterol, triglyceride and body mass index) were each associated with increases in plasma viscosity, coagulation factors, and imbalance of coagulation over fibrinolysis (increased ratio of fibrinopeptide A/fibrinopeptide B beta 15-42). Increased viscosity and fibrinogen in smokers were partly reversed in ex-smokers, but the imbalance of coagulation and fibrinolysis persisted. Cholesterol and triglyceride were also associated with increased antiplasmin activity. In men with angina, only fibrinogen was elevated compared to controls. We suggest that increased plasma viscosity and an imbalance of coagulation over fibrinolysis may be mechanisms by which known risk factors promote arterial thrombosis, but are not present in stable angina.  相似文献   
995.
Pregnant rats were injected with a single dose of methylazoxymethanol (MAM, 25 mg/kg) on gestational day 14, 15, 16, 17, 18 or 19 and offspring were tested for their physical development, reflex development and spontaneous activity. MAM treatment did not affect gestational and litter parameters at any of the time of administration studied. Treatment at gestational day 14 (GD14) had the most severe effect on functional neurodevelopment until weaning: righting reflex at surface, chimney test, horizontal wire test resulted altered. Administration at GD15, 16, 18, 19 did not affect the performance in these tests. Offspring treated at GD17 showed a delayed eye opening and an impaired performance in the horizontal wire test. When tested at 50 days of age on the rotarod, all the treated groups performed worse than controls with the exception of GD19 treated offspring. Administration at GD14 and GD15 resulted in increased spontaneous activity of the offspring at 21 days but not at 60 days of age. Different degrees of microencephaly were observed for all treated groups. The results indicate that alterations of physical and behavioral development induced by MAM treatment are dependent on the time of MAM administration, and specific behavioral tests are able to detect different abnormalities and differentiate among treatment groups. Some alterations observed in MAM rats undergo to adaptive changes during maturation of the CNS.  相似文献   
996.
SNAP-25 immunoreactivity was translocated into the endings of the processes induced in PC12 cells by dibutyryl-cAMP-treatment. Conversely, the protein was not present in the endings of the processes seen after NGF-treatment unless dibutyryl-cAMP was used simultaneously. This redistribution of SNAP-25 immunoreactivity appeared to be dependent upon new protein synthesis. Finally, dibutyryl-cAMP was capable of inducing SNAP-25 expression.  相似文献   
997.
The postnatal evolution of depolarizing after-potentials (DAPs) and after-hyperpolarizations (AHPs) was studied in rat CA1 hippocampal neurones (5-68 days of age) using in vitro slices. Results were pooled into 4 age groups: P5-9, P10-16, P17-24 and P26-68. In P5-9 cells, DAPs were seen as passive signals, with a time constant similar to the time constant of the membrane. The evolution of the DAP was characterized by a decrease in amplitude, an increase in duration and a change in contour. In P10-16 and P17-24 cells, the DAPs often had a plateau or a hump-like shape which increased the probability of firing and the occurrence of spike doublets. The firing pattern and bursting behaviour of P10-16 CA1 neurones differed from the pattern typical of the adult. P5-9 and P10-16 cells had post-burst AHPs with a smaller amplitude and a more prolonged early phase than at late stages of development.  相似文献   
998.
The concentrations of beta-endorphin and cholecystokinin were measured in fresh resting peripheral mononuclear cells obtained from rats and human subjects in basal conditions and after different pharmacological treatments. Both in the human and the rat, beta-endorphin concentrations in mononuclear cells, increased after treatment with serotoninergic agonists, decreased after dopaminergic or GABAergic drugs, while the respective antagonists exerted the opposite effect. In vitro, serotoninergic and GABAergic compounds confirmed their roles in the modulation of beta-endorphin in mononuclear cells. Cholecystokinin was never affected by the pharmacological treatments.  相似文献   
999.
Although the initial phase of receptor-mediated Ca2+ signaling, involving Ca2+ release from intracellular stores by inositol 1,4,5-trisphosphate, is relatively well characterized, the nature of the organelle releasing Ca2+ is a controversial subject. At issue is the question of whether Ca2+ is released from the endoplasmic reticulum, or from a more specialized organelle called the 'calciosome'. In this review, we attempt to analyse the arguments for and against these two views, and attempt to reconcile some of the apparently conflicting findings by proposing a hypothetical model of the inositol 1,4,5-trisphosphate-sensitive Ca2+ pool.  相似文献   
1000.
The effects of certain experimental variables on rodents brain and liver alcohol--(ADH) and aldehyde-dehydrogenase (LALDH) were evaluated. The in vivo and in vitro effect of chlorpromazine on these enzymes was determined. Short-term housing under complete darkness differentially inhibited ADH and ALDH in distinct brain regions with ADH showing more sensitivity than ALDH. The hepatic enzymes studied were not affected by such housing conditions but a non-competitive inhibition of L-ALDH occurred as a consequence of exposure to UV lighting for 3 consecutive weeks. Short-term treatment with chlorpromazine inhibited striatal ADH which was not affected by experimentally-induced hypothermia. Likewise, both hepatic and testicular ADH were noncompetitively inhibited in vitro by chlorpromazine. The results suggest sensitivity of brain and hepatic ADH to environmental housing conditions and indicate a similarity between peripheral and cerebral ADH responses to chlorpromazine. The modulation of ADH and/or ALDH may facilitate the formation of endogenous biogenic amines derived alkaloids which have been implicated in alcohol and extrapyramidal side effects.  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