全文获取类型
收费全文 | 259225篇 |
免费 | 5619篇 |
国内免费 | 424篇 |
专业分类
耳鼻咽喉 | 3272篇 |
儿科学 | 7896篇 |
妇产科学 | 5308篇 |
基础医学 | 35907篇 |
口腔科学 | 5731篇 |
临床医学 | 20071篇 |
内科学 | 55817篇 |
皮肤病学 | 6789篇 |
神经病学 | 22557篇 |
特种医学 | 7692篇 |
外国民族医学 | 101篇 |
外科学 | 31276篇 |
综合类 | 1239篇 |
一般理论 | 67篇 |
预防医学 | 23324篇 |
眼科学 | 4860篇 |
药学 | 17652篇 |
9篇 | |
中国医学 | 761篇 |
肿瘤学 | 14939篇 |
出版年
2024年 | 1366篇 |
2023年 | 1437篇 |
2022年 | 1194篇 |
2021年 | 4071篇 |
2020年 | 2387篇 |
2019年 | 4443篇 |
2018年 | 7912篇 |
2017年 | 5156篇 |
2016年 | 5181篇 |
2015年 | 5769篇 |
2014年 | 6324篇 |
2013年 | 10009篇 |
2012年 | 16964篇 |
2011年 | 17047篇 |
2010年 | 8663篇 |
2009年 | 6629篇 |
2008年 | 14694篇 |
2007年 | 15709篇 |
2006年 | 14489篇 |
2005年 | 14365篇 |
2004年 | 13504篇 |
2003年 | 12381篇 |
2002年 | 11713篇 |
2001年 | 6553篇 |
2000年 | 6739篇 |
1999年 | 5986篇 |
1998年 | 1105篇 |
1997年 | 911篇 |
1996年 | 835篇 |
1992年 | 3360篇 |
1991年 | 2970篇 |
1990年 | 2871篇 |
1989年 | 2605篇 |
1988年 | 2454篇 |
1987年 | 2301篇 |
1986年 | 2169篇 |
1985年 | 1955篇 |
1984年 | 1449篇 |
1983年 | 1223篇 |
1979年 | 1240篇 |
1978年 | 880篇 |
1977年 | 827篇 |
1975年 | 826篇 |
1974年 | 1010篇 |
1973年 | 1018篇 |
1972年 | 967篇 |
1971年 | 946篇 |
1970年 | 875篇 |
1969年 | 932篇 |
1968年 | 802篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Marie-Claude Vézina Claude A. Trépanier Pierre C. Nicole Martin R. Lessard 《Journal canadien d'anesthésie》2007,54(2):124-128
PURPOSE: The Esophageal-Tracheal Combitube (Combitube) is widely used for the management of the airway during cardiopulmonary resuscitation in the pre-hospital setting. Although serious complications have been reported with the Combitube, there is a paucity of data relative to the frequency and nature of such complications. The objective of this retrospective study was to determine the incidence and the nature of complications associated to the Combitube in the pre-hospital setting. METHODS: Since 1993, in the Quebec City Health Region, the basic life support treatment algorithm for emergency medical technicians has included the use of a Combitube as the primary airway device for management of all patients presenting with cardiac or respiratory arrest. The database of the emergency coordination services was searched for the period between 1993 and 2003 (2,981 patients). Only those patients who survived at least 12 hr were included. Medical records of these patients were reviewed to identify complications related to the use of the Combitube. RESULTS: Two-hundred-eighty (280) patients were identified. Fifty-eight (58) patients (20.7%, confidence interval (CI)95%=16.0%-25.4%) presented 69 complications: aspiration pneumonitis (n=31), pulmonary aspiration (n=16), pneumothorax (n=6), upper airway bleeding (n=4), esophageal laceration (n=3), sc emphysema (n=2), esophageal perforation and mediastinitis (n=2), tongue edema (n=2), vocal cord injury (n=1), tracheal injury (n=1), and pneumomediastinum (n=1). Thirteen of these complications (12 patients, 4.3%, CI95%=2.0%-6.3%) were judged as most likely resulting from trauma associated with insertion of the Combitube. CONCLUSION: The use of the Combitube in the pre-hospital setting is associated with a notable incidence of serious complications. 相似文献
92.
Thomas Rimmelé Sophie Malhière Alexandre Ben Cheikh Emmanuel Boselli Monique Bret Charles-Eric Ber Paul Petit Bernard Allaouchiche 《Journal canadien d'anesthésie》2007,54(8):652-656
PURPOSE: In France, legislation mandates that the clinical diagnosis of brain death be confirmed by one paraclinical test before organ donation is allowed. That test may be either the electroencephalogram (EEG) or cerebral angiography. We report a case in which the clinical diagnosis of brain death was first confirmed by two EEGs performed according to the French guidelines, but ruled out by cerebral angiography. Considering that the EEG is no longer recommended to establish the diagnosis of brain death, we discuss the relevance of maintaining the EEG for brain death diagnosis in France. CLINICAL FINDINGS: A 58 yr-old man was admitted to the intensive care unit because of coma secondary to a massive subarachnoid hemorrhage with herniation below the falx shown by computed tomography. Clinical criteria of brain death were rapidly present. Two EEGs first confirmed the diagnosis but a four-vessel cerebral angiography was finally performed because the patient moved spontaneously. This cerebral angiography showed flow in the right internal carotid artery. A computed tomography performed the next day definitely confirmed the absence of brain death and organ donation did not occur. CONCLUSIONS: This case demonstrates the limitations of the EEG for this indication and suggests that angiography should be preferred. French legislation is probably maladjusted and would benefit by incorporating guidelines of other countries like Canada. International harmonization of criteria for brain death diagnosis would also be welcome. 相似文献
93.
François Béïque Mohamed Ali Scott MacKenzie Mark Hynes 《Journal canadien d'anesthésie》2007,54(2):158-159
94.
Catalase enzyme mutations and their association with diseases. 总被引:2,自引:0,他引:2
Enzyme catalase seems to be the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide at high concentrations is a toxic agent, while at low concentrations it appears to modulate some physiological processes such as signaling in cell proliferation, apoptosis, carbohydrate metabolism, and platelet activation. Benign catalase gene mutations of 5' noncoding region (15) and intron 1 (4) have no effect on catalase activity and are not associated with disease.Catalase gene mutations have been detected in association with diabetes mellitus, hypertension, and vitiligo. Decreases in catalase activity in patients with tumors is more likely to be due to decreased enzyme synthesis rather than to catalase mutations.Acatalasemia, the inherited deficiency of catalase has been detected in 11 countries. Its clinical features might be oral gangrene, altered lipid, carbohydrate, homocysteine metabolism and the increased risk of diabetes mellitus. The Japanese, Swiss, and Hungarian types of acatalasemia display differences in biochemical and genetic aspects. However, there are only limited reports on the syndrome causing these mutations.These data show that acatalasemia may be a syndrome with clinical, biochemical, genetic characteristics rather than just a simple enzyme deficiency. 相似文献
95.
AIM: The authors report an alternative procedure to carotid endarterectomy with internal carotid artery (ICA) segmental resection and end-to-end anastomosis associated with temporary shunt and venous patch angioplasty. Design: prospective cohort study. METHODS: Between May 1995 and December 2004, 192 patients underwent 200 primary CEAs for significant ICA stenosis. There were 131 men and 61 women with a mean age of 72.4+/-8.4 years. The indications for CEA were asymptomatic lesions in 51.5%, transient ischemic attack in 27.5% and stroke in 21%. RESULTS: The combined early morbidity and mortality rate was 2%. Two patients died, one due to fatal intracerebral hemorrhage and the second patient died of acute mesenteric ischemia. Neurological complications occurred in 2 patients, including 1 TIA and 1 nondisabling cerebrovascular accident. Non-neurological complications occurred in 26 patients (13.5%). Seventeen patients (8.8%) developed hypertension, 3 neck hematomas (1.5%) required surgical evacuation, 1 patient had reversible supraventricular arrhythmia (0.5%) and 1 patient had pneumonia (0.5%). Furthermore, 1 asymptomatic carotid occlusion was identified (0.5%) and 3 patients suffered permanent cranial nerve injury (1.5%). Mean follow-up was 45.7 months and there were 41 late deaths (21.8%). Survival rates at 1 and 5 years were 96.7+/-1.2% and 73.58+/-4.2%, respectively. CONCLUSIONS: CEA with ICA shortening and reanastomosis is a safe and reliable procedure without any increase in morbidity or mortality. 相似文献
96.
A high-quality distance preserving output representation is provided to the neural gas (NG) network. The nonlinear mapping is determined concurrently along with the codebook vectors. The adaptation rule for codebook positions in the projection space minimizes a cost function that favors the trustworthy preservation of the local topology. The proposed visualization method, called OVI-NG, is an enhancement over curvilinear component analysis (CCA). The results show that the mapping quality obtained with OVI-NG outperforms the original CCA, in terms of the trustworthiness, continuity, topographic function and topology preservation measures. 相似文献
97.
Keita Mayanagi Tamás Gáspár Prasad V G Katakam Béla Kis David W Busija 《Journal of cerebral blood flow and metabolism》2007,27(2):348-355
Activation of mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels protects the brain against ischemic or chemical challenge. Unfortunately, the prototype mitoK(ATP) channel opener, diazoxide, has mitoK(ATP) channel-independent actions. We examined the effects of BMS-191095, a novel selective mitoK(ATP) channel opener, on transient ischemia induced by middle cerebral artery occlusion (MCAO) in rats. Male Wister rats were subjected to 90 mins of MCAO. BMS-191095 (25 microg; estimated brain concentration of 40 micromol/L) or vehicle was infused intraventricularly before the onset of ischemia. In addition, the effects of BMS-191095 on plasma and mitochondrial membrane potentials and reactive oxygen species (ROS) production in cultured neurons were examined. Finally, we determined the effects of BMS-191095 on cerebral blood flow (CBF) and potassium currents in cerebrovascular myocytes. Treatment with BMS-191095 24 h before the onset of ischemia reduced total infarct volume by 32% and cortical infarct volume by 38%. However, BMS-191095 administered 30 or 60 mins before MCAO had no effect. The protective effects of BMS-191095 were prevented by co-treatment with 5-hydroxydecanoate (5-HD), a mitoK(ATP) channel antagonist. In cultured neurons, BMS-191095 (40 micromol/L) depolarized the mitochondria without affecting ROS levels, and this effect was inhibited by 5-HD. BMS-191095, similar to the vehicle, caused an unexplained but modest reduction in the CBF. Importantly, BMS-191095 did not affect either the potassium currents in cerebrovascular myocytes or the plasma membrane potential of neurons. Thus, BMS-191095 afforded protection against cerebral ischemia by delayed preconditioning via selective opening of mitoK(ATP) channels and without ROS generation. 相似文献
98.
M Zentilin Boyer P de Lonlay N Seta M Besnard C Pélatan H Ogier J P Hugot C Faure J M Saudubray J Navarro J P Cézard 《Archives de pédiatrie》2003,10(7):590-595
Congenital disorders of glycosylation type I (GDG-I) is a class of genetic multisystem disorders characterised by defective glycosylation of glycoproteins. The characteristics and mechanisms of failure to thrive and intestinal diseases present in CDG-I are anectodal. PATIENTS AND METHODS: The aim of this study was to analyse 7 CDG-I (4 CDG-Ia, 2 CDG-Ib and 1 CDG-Ix) with important digestive symptoms and failure to thrive in order to characterise the mechanisms implied. RESULTS: Four children had no skin abnormality or dysmorphia (1 CDG-Ia, 2 CDG-Ib, 1 CDG-Ix). An encephalopathy with cerebellar hypoplasia was present only in the 4 CDG-Ia. Failure to thrive and diarrhea were present during the first month of life in 6 and appeared at 5 years in one CDG-Ia associated to mild or severe hepatopathy in all patients. One CDG-Ia, 1 CDG-Ib, 1 CDG-Ix had an exsudative enteropathy. A positive steatorrhea was present in 3 patients. Five patients had an abnormal small bowel biopsy. Abnormalities were variable: moderate inflammation of the chorion without villous atrophy in 2, intra-enterocyte fat accumulation without villous atrophy in 2, and partial villous atrophy with lymphangectasia in 1. In 2 CDG-Ia the intestinal biopsy was normal. Enteral nutrition in 4 and parenteral nutrition in 2 were effective in 4 patients and 1 patient with an exsudative enteropathy respond to a free fat diet (CDG-Ix). CONCLUSION: The digestive symptoms with failure to thrive is a common feature of CDG-I and could be the first symptoms. The diagnostic should be suspected if no other cause is found. Mechanisms of the intestinal symptoms appear to be multiple such as inflammation, abnormal enterocyte lipid transport or intestinal permeability related to the abnormal glycosylation of intestinal mucosa glycoproteins. 相似文献
99.
S Varela J Mendez C González de la Cuesta I Iglesias C González M Menéndez 《Journal of investigational allergology & clinical immunology》2003,13(2):124-130
A retrospective study was performed to describe the features of the pollinosis caused by Betula in the area of Ourense, Spain. The pollen count was carried out with a Lanzoni volumetric Hirts spore trap (1993-2000). The Betula pollen represented 5% over the annual total (annual mean quantity: 965 grains). It was present in the air from March to mid-May. The highest peaks took place in April (maximum values mean: 131 grains/m3). The medical records of 222 patients (mean age 25.66 years) diagnosed with pollinosis (1998-2000), who lived at less than 30 km. from the spore trap, were reviewed. In all of them, the skin-prick test (SPT) was carried out with pollen allergens. The percentages of positive SPT were: Lolium perenne, 91.89% (16.6% monosensitized); Plantago lanceolata, 71.17% (1.26% monosensitized); Betula alba, 41.89% (10.75% monosensitized); Platanus hybrida, 34.95%; Olea europea, 10.36%; and Parietaria judaica, 6.3%. The mean age of Betula monosensitized patients was 44.7 years. The majority of them had symptoms in March-April, 40% had asthma symptoms, 80% had lived in Central Europe, and 30% of them presented an oral allergy syndrome to fruits. There were 41.93% of the patients with positive SPT to Betula pollen who had asthma symptoms, in comparison with 23.25% of the patients with negative SPT to Betula (p = 0.0034). There were 20.28% of the patients with positive SPT to Betula pollen, who had lived in Central Europe, in comparison with 4.27% of the patients with negative SPT to Betula, p: 0.00049. The relative risk of sensitization was 2.05. CONCLUSIONS: Betula pollen was the second cause of clinical pollinosis in our patients, after grass, being responsible of the symptoms in the early spring, in a small number of the patients in their forties. The presence of asthma was higher in Betula sensitized patients, and the residence in Central Europe was a sensitization risk factor. 相似文献
100.
J A San Román I Vilacosta J Zamorano C Almería F J Cortés E Iturralde L Sánchez Harguindey 《Revista espa?ola de cardiología》1992,45(3):219-221
Three cases with suspected pulmonary artery embolism are presented, in which transesophageal echocardiography showed a mass in the right pulmonary artery consistent with thrombus. The relevant diagnostic contributions of transesophageal echocardiography are discussed. 相似文献