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   48370篇
  免费   3971篇
  国内免费   167篇
耳鼻咽喉   555篇
儿科学   1402篇
妇产科学   1016篇
基础医学   6619篇
口腔科学   1470篇
临床医学   5068篇
内科学   10531篇
皮肤病学   1116篇
神经病学   4723篇
特种医学   1380篇
外国民族医学   2篇
外科学   6557篇
综合类   347篇
一般理论   35篇
预防医学   4376篇
眼科学   665篇
药学   3365篇
中国医学   182篇
肿瘤学   3099篇
  2023年   220篇
  2022年   537篇
  2021年   1076篇
  2020年   805篇
  2019年   1288篇
  2018年   1507篇
  2017年   1195篇
  2016年   1229篇
  2015年   1499篇
  2014年   1829篇
  2013年   2538篇
  2012年   3090篇
  2011年   3359篇
  2010年   2055篇
  2009年   1865篇
  2008年   2805篇
  2007年   2857篇
  2006年   2711篇
  2005年   2712篇
  2004年   2534篇
  2003年   2501篇
  2002年   2491篇
  2001年   730篇
  2000年   643篇
  1999年   633篇
  1998年   510篇
  1997年   467篇
  1996年   377篇
  1995年   406篇
  1994年   337篇
  1993年   323篇
  1992年   394篇
  1991年   382篇
  1990年   352篇
  1989年   290篇
  1988年   290篇
  1987年   258篇
  1986年   267篇
  1985年   242篇
  1984年   232篇
  1983年   184篇
  1982年   232篇
  1981年   215篇
  1980年   199篇
  1979年   190篇
  1978年   149篇
  1977年   143篇
  1976年   116篇
  1975年   115篇
  1974年   106篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46–81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG.  相似文献   
83.
There remains doubt about the need for gastroenterostomy in patients with advanced cancer of the pancreatic head, performed either prophylactically or when passage of food becomes impossible. The records of 142 patients admitted for advanced pancreatic cancer to the Erasmus University Hospital over a period of 11 years were reviewed. We concentrated especially on the pre- and postoperative intake of food in cases involving gastroenterostomy and the morbidity and mortality associated with abdominal surgery in these patients. Of 129 patients without symptoms of gastric outlet obstruction at the time of diagnosis, 31 underwent prophylactic gastroenterostomy. The procedure did not prevent gastric outlet obstruction in 4 patients. Of the remaining 98 patients, 15 developed gastric outlet obstruction. Cox proportional hazards analysis showed no significant difference in the interval to the occurrence of a symptomatic obstruction between these two groups, taking into account other covariables. Postoperative complications and mortality regarding a gastroenterostomy were high, ranging from 9% to 41% and 11% to 33%, respectively. Our results do not indicate that prophylactic gastroenterostomy may significantly prevent future gastric outlet obstruction; therefore, as it also increases morbidity, it should not be performed. A gastroenterostomy to relieve symptoms should be considered carefully, as the success rate is low and is accompanied by a considerable incidence of morbidity and mortality.
Resumen Persiste la duda sobre la necesidad de practicar gastroenterostomía en pacientes con cáncer avanzado de la cabeza del páncreas, así sea profiláctica o en presencia de obstrucción al paso de los alimentos. Se revisaron las historias de 142 pacientes con cáncer avanzado de la cabeza del páncreas en el Hospital de la Universidad de Erasmo observados en un periodo de 11 años. El estudio se concentré especialmente sobre la ingesta pre y postoperatoria de alimentos en los pacientos con gastroenterostomía y en la morbilidad y mortalidad asociada con la cirugía abdominal. De 129 pacientes libres de síntomas de obstrucción en el momento del diagnóstico, 31 fueron sometidos a gastroenterostomía profiláctica; el procedimiento no logró prevenir la obstrucción gástrica en 4 casos. De los 98 pacientes restantes, 15 desarrollaron obstrucción gástrico. El análisis proporcional de Cox no demostró diferencia significativa en el intervalo transcurrido hasta la aparición de los sintomas entre los dos grupos, tomando en consideración diversas variables. Las tasas de complicaciones y de mortalidad postoperatoria en relación con la gastroenterostomía fueron elevadas, 9–41% y 11–33%, respectivamente. Nuestros resultados no indican que la gastroenterostomía profiláctica pueda prevenir la obstrucción gástrica y, por cuanto incrementa la morbilidad, no debe ser realizada. La gastroenterostomía por razones de sintomatologia debe ser cuidadosamente considerada, puesto que la tasa de éxito es baja y se acompana de considerable morbilidad y mortalidad.

Résumé Réaliser une gastroentérostomie de faÇon prophylactique ou seulement lorsque l'alimentation devient impossible chez un patient ayant un cancer de la tÊte du pancréas reste une question sans réponse. Les dossiers de 142 patients ayant un cancer avancé de la tÊte du pancréas, observés à l'HÔpital Universitaire Erasmus en l'espace de 11 ans, ont été revus. Nous avons noté la possibilité d'alimentation en périodes préet postopératoire ainsi que la morbidité et mortalité en rapport avec la chirurgie chez ces patients. Des 129 patients n'ayant pas de symptÔmes d'obstruction postpylorique au moment du diagnostic, 31 ont eu une gastroentérostomie à titre prophylactique. Cette intervention n'a pu prévenir l'obstruction chez 4 de ces patients. Des 98 autres patients, 15 ont développé une obstruction postpylorique. Une analyse multifactorielle selon le modèle de Cox n'a pu démontrer de différence significative entre les deux groupes pour l'intervalle entre le moment du diagnostic et la survenue de l'obstruction. Le taux de complications et de décès postopératoires après gastroentérostomie était élevée, variant respectivement entre 9% et 41% et 11% et 33%. Nos résultats indiquent que la gastroentérostomie à titre prophylactique ne prévient pas la survenue d'une obstruction postpylorique mais qu'elle accroÎt la morbidité. Dans ces conditions, la gastroentérostomie ne devrait Être réalisée qu'en cas d'obstruction symptomatique, mais en sachant qu'elle n'est pas toujours couronnée de succès et que les taux de mortalité et de morbidité ne sont pas nuls.
  相似文献   
84.
To study the effect of different schedules of allergen administration on the early (EAR) and late allergic reaction (LAR), 15 asthmatic patients with dual response after allergen challenge were submitted to two consecutive bronchoprovocation tests (BPT). BPT1 was carried out with semilogarithmic increase of allergen doses until a FEV1 drop of 20% was recorded. BPT2 was performed 2 weeks later using the highest allergen dose that had elicited the dual reaction in BPT1. Both EAR and LAR were very similar for a given patient. As the allergen dose used in BPT2 is smaller than the cumulative allergen dose administered in BPT1, this protocol takes into account a possible influence on BPT2 of bronchial hyperreactivity induced by BPT1 performed 2 weeks before.  相似文献   
85.
Laparoscopic hysterectomy   总被引:1,自引:0,他引:1  
Summary Thirty-three patients were selected for laparoscopic hysterectomy and operated on in the Department of Obstetrics, Gynecology and Reproductive Medicine of Clermont-Ferrand University Hospital. Surgical techniques included blunt dissection with scissors and bipolar coagulation to achieve hemostasis. A case was considered successful when all the uterine vessels were treated by laparoscopy. Twenty-four cases were completed laparoscopically (72.7%). None of these patients had postoperative bleeding; 22 had an uneventful postoperative recovery. Nine procedures were converted to laparotomy (27.3%), five because of a difficult or unsatisfactory hemostasis. We conclude that in selected cases, a total hysterectomy can be performed safely by experienced laparoscopists. Further technological progress is necessary to make this procedure more acceptable. Its value as compared to the others will have to be demonstrated.  相似文献   
86.
The aim of surgical treatment of a fixed stapes is to restore an as effective as possible impedance transfer of the ossicular chain and acoustic impedance of the annular ligament of the footplate, when it has lost elasticity, and this in order to achieve the best possible physiological vibration of the inner ear fluids.  相似文献   
87.
Hepatobiliary scintigraphy in a patient with bilhemia   总被引:1,自引:0,他引:1  
A 4-year-old child referred for acute jaundice following percutaneous needle biopsy of the liver underwent hepatobiliary scintigraphy. Although all conventional liver tests suggested preservation of hepatocyte function, the tracer uptake in the liver appeared dramatically reduced at scintigraphy and the blood pool activity did not decrease significantly until the end of the study. Visualization of the bile ducts indicated, however, that the tracer was taken up by the hepatocyte and further excreted into the biliary tree. There was no tracer pooling in the biliary tree although no bowel activity was observed, even on delayed images. The association of persistent blood pool activity, bile duct visualization without tracer pooling, and nonvisualization of the bowel was caused by a continuous recirculation of the tracer from the biliary tree into the bloodstream. The presence of a biliovenous fistula was further proven by percutaneous transhepatic cholangiography performed 24 h later. Since 1975, only 16 cases of bilhemia have been reported. To the best of our knowledge the scintigraphic pattern of this rare but lifethreatening complication has not previously been reported.  相似文献   
88.
双联抗血小板疗法预防缺血再发   总被引:3,自引:0,他引:3  
本文对应用双联抗血小板聚集药在预防缺血再发方面较应用单药的优势进行了探讨.动脉粥样硬化是一种隐袭性的全身性过程,可累及多处血管床,包括脑动脉、冠状动脉和周围动脉.粥样硬化斑块破裂是血小板活化、聚集和血栓形成进程中的刺激因素之一.因为该病是沿着整个脉管系统发展的,所以对有任何一种动脉粥样硬化临床表现的患者来说,其他血管床也极易受到侵犯.不同的血管病有着共同的易患危险因素.缺血性冠心病和脑血管病是美国三大常见死亡原因中的两种.阿司匹林在心肌梗死和卒中的二级预防方面的有效性已在众多的研究中得到证实.潘生丁在降低心肌梗死、卒中和血管性死亡方面并不比阿司匹林更好,但噻氯匹定和氯吡格雷却明显优于阿司匹林.目前正在进行评估联合应用抗血小板聚集药预防缺血再发的有效性的临床研究.体外试验和临床研究均支持联合应用两种机制不同的抗血小板聚集药的理论.双联应用抗血小板聚集疗法可增强对血小板聚集和血栓形成的抑制作用.联合应用抗血小板聚集药以不同的作用机制抑制血栓形成途径中的多个位点,有可能进一步改善患者远期临床转归.#在预防缺血再发方面,应用双联抗血小板聚集药较应用单药可能更具优势.  相似文献   
89.
The mapping of 5-HT2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands. Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150 or123I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT2A receptors. This study reports on preliminary123I-5-I-R91150 SPET, wholebody and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately 2% of total body counts at 180 min post injection (p.i.). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice multi-detector system SEM-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free from 5HT2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately 100–120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100 min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic data on the distribution of 5-HT2A receptors in (cerebral cortex>striatum>cerebellum). These findings suggest that123I-5-I-R91150 may be used for the imaging of 5-HT2A receptors in the living human brain with SPET.  相似文献   
90.
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