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   2837篇
  免费   153篇
  国内免费   31篇
耳鼻咽喉   74篇
儿科学   64篇
妇产科学   72篇
基础医学   448篇
口腔科学   42篇
临床医学   241篇
内科学   651篇
皮肤病学   91篇
神经病学   199篇
特种医学   91篇
外科学   446篇
综合类   13篇
预防医学   133篇
眼科学   48篇
药学   145篇
中国医学   1篇
肿瘤学   262篇
  2023年   33篇
  2022年   43篇
  2021年   90篇
  2020年   51篇
  2019年   61篇
  2018年   89篇
  2017年   64篇
  2016年   75篇
  2015年   89篇
  2014年   108篇
  2013年   144篇
  2012年   197篇
  2011年   215篇
  2010年   133篇
  2009年   101篇
  2008年   169篇
  2007年   173篇
  2006年   178篇
  2005年   191篇
  2004年   184篇
  2003年   142篇
  2002年   126篇
  2001年   27篇
  2000年   29篇
  1999年   26篇
  1998年   29篇
  1997年   23篇
  1996年   26篇
  1995年   18篇
  1994年   13篇
  1993年   9篇
  1992年   22篇
  1991年   11篇
  1990年   10篇
  1989年   22篇
  1988年   11篇
  1987年   8篇
  1986年   8篇
  1985年   12篇
  1984年   3篇
  1983年   9篇
  1981年   3篇
  1980年   5篇
  1979年   5篇
  1976年   8篇
  1975年   3篇
  1968年   3篇
  1966年   2篇
  1964年   2篇
  1963年   2篇
排序方式: 共有3021条查询结果,搜索用时 15 毫秒
31.
Information on genetic changes involved in the progression of gastroenteropancreatic (GEP) endocrine tumours is scanty. On the other hand, the identification of molecular markers of malignancy could be crucial for the prognostic evaluation of these neoplasms, which is hardly predictable on the basis of conventional histological criteria. An association of X-chromosome deletions with malignancy has already been found in gastric endocrine tumours. To investigate this further, a comparative loss of heterozygosity (LOH) analysis was performed on 17 pancreatic endocrine tumours (PETs) and 17 intestinal (ten ileal, six appendiceal, and one rectal) carcinoids from female patients. The relationship of X-chromosome LOH with the ploidy status of the neoplasms was also investigated. LOH was found in six of eight malignant PETs (60% of the informative markers), but was infrequent in the nine benign ones (4.5%). In contrast, although retention of heterozygosity was consistently observed in benign midgut tumours, LOH was infrequent in malignant carcinoids (15%). No correlation was found between LOH and the ploidy status. These results indicate an association between X-chromosome LOH and malignancy in foregut endocrine tumours. The lack of such an association in midgut carcinoids suggests that different molecular mechanisms are involved in the progression of these two categories of endocrine neoplasms, which are otherwise considered to be closely related. These findings emphasize the need for further molecular studies on GEP endocrine tumours, carefully subdivided according to their anatomical site of origin.  相似文献   
32.
Persistent HBV and HCV infection represent major causes of chronic liver disease with a high risk of progression to liver cirrhosis and hepatocellular carcinoma (HCC). Conventional protein-based vaccines are highly efficacious in preventing HBV infection; whereas in therapeutic settings with chronically infected patients, results have been disappointing. Prophylactic vaccination against HCV infection has not yet been achieved due to many impediments including frequent spontaneous mutations of the virus with escape from immune system control. Using animal models it has been demonstrated that DNA-based immunisation strategies may overcome this problem because of their potential to induce immunity against multiple viral epitopes. DNA-based vaccines mimic the effect of live attenuated viral vaccines, eliciting cell mediated immunity in addition to inducing humoral responses. Efficacy may further be improved by addition of DNA encoding immunomodulatory cytokines and more recently, direct genetic modulation of antigen-presenting cells, such as dendritic cells (DC), has been shown to increase antigen-specific immune responses. This review focuses on immunological aspects of chronic HBV and HCV infection and on the potential of DNA- and DC-based vaccines for the treatment of chronic viral hepatitis.  相似文献   
33.
Neurosurgical Review - Capillary hemangiomas (CHs) of the central nervous system represent a rare diagnosed pathology. CHs are benign vascular tumors whose most common manifestations are dermal and...  相似文献   
34.
Neurosurgical Review - The surgical injury of the intracranial portion of the facial nerve (FN) is a severe complication of many skull base procedures, and it represents a relevant issue in terms...  相似文献   
35.
BackgroundPeyonie’s disease (PD) mostly affects males in the fifth decade of life, with a prevalence in the general population ranging between 0.5% and 20.3%. The pathology of PD is characterized by fibrosis of the tunic albuginea of the cavernous bodies of the penis, with the presence of pain in the erection and penile deformity. This is associated with decreased sexual function for both participants. The objective of the study was to investigate the influence of PD pathology on both male patients’ and their female partners’ sexual spheres, and analyze changes in sexual function and perception following penile correction surgery.MethodsProspective study, we included male patients with PD and their female partner sexually active. Patients underwent corporoplasty with multiple plications. The male and female sexuality was evaluated before surgery and three months after male treatment by the Female sexual Function Index (FSFI); International Index of Erectile Function (IIEF); Visual Analogical Scale (VAS).ResultsFrom January 2018 to November 2019 we included 35 couple. The female subjects before partner’s surgery presented dyspareunia, loss of sexual desire, inability to achieve orgasm, and sexual dissatisfaction. At three months after surgical treatment there was an improvement of sexual function in both male patients and female partners (desire P<0.0001, arousal P<0.0001, lubrification P<0.0001, orgasm P<0.0001, satisfaction P<0.0001, pain P<0.0001). As regarding male patients the pain decreased significantly (VAS score from 6 to 2.5), while there was no statistically significant improvement in erectile function (P=0.05).ConclusionsOur findings suggest that a viable approach to treatment of PD patients that involves their partners could lead to better functional and psychological results.  相似文献   
36.
Survival statistics of 4135 incident cases of digestive system cancers in the Umbria region of Italy are reported. The original data are derived from an ad hoc survey carried out in the period 1978--1982. Observed and relative rates at 1, 5 and 10 years are presented separately by sex and age (< 60 and 60 years). In both sexes there are very short survival rates for liver, bile duct and pancreas cancers, whereas about 50% of colon and rectum cancer patients survived at five years. About 20% stomach cancer patients survived at the same time. In males the survival rate for oesophagus cancer is close to 10%. The rates at ten years confirm the trend. Comparisons between sexes show that there is no significant differences in age at first diagnosis. Survival values are higher in females only for rectum cancers. In both sexes, for stomach, colon and rectum sites younger patients had a significantly longer survival than older ones.  相似文献   
37.
    
In 1945, Lennox was the first to describe the epileptic states mainly expressed by various degrees of consciousness disturbance, which have their onset in children who present epileptic absences correlated with ictal EEG patterns of spike-wave complex discharges at about 3 Hz. As the clinical picture seemed to be similar to an uninterrupted series of absences, this led to the definition Petit Mal Status (PMS). Many authors have subsequently reported that PMS can occur in epileptic subjects who have never presented absences (and even in subjects without a previous history of epilepsy) and that the related EEG pictures were characterised by paroxysmal generalized activity of various morphology, but hardly ever consisted of the continuous rhythmic spike-wave or polyspike-wave complexes at 3 Hz found in petit mal absences. Finally, in reporting the onset and recurrence of this condition typically in adults and the elderly, some authors have proposed the existence of a particular form of PMS (dependent on different types of pathologic factors and characterising a specific syndrome of this age) that is different from that of the real PMS typical of childhood and related to petit mal absences. This paper describes fifteen patients in whom the onset of the condition occurred at different ages, and who seem to exemplify the various possible clinical expressions of PMS, with the aim of making a contribution towards the better nosographic definition of this epileptic condition.On the basis of our study, we sustain that the so-called PMS is a seizure type of Idiopathic Generalized Epilepsy which may appear at nearly all ages, and may occur in isolation or in association with other epileptic manifestations, but cannot itself be considered as characterising one or more age-dependent syndromes.
Sommario Lennox per primo (1945) descrisse degli Stati Epilettici esprimentisi principalmente con un disturbo della coscienza di grado variabile, insorgenti in bambini che presentavano Assenze epilettiche, correlati con pattern EEG ictale di scariche di complessi PO a circa 3 Hz. Il quadro clinico sembrava pertanto poter essere assimilato al susseguirsi ininterrotto di Assenze, donde la definizione di Petit Mal Status (PMS). Successivamente molti Autori hanno segnalato che il PMS poteva ricorrere in soggetti epilettici che non avevano mai presentato Assenze o, addirittura, in soggetti senza precedenti di Epilessia, e che i quadri EEG correlati erano caratterizzati da attività pasossistiche generalizzate di varia morfologia, ma quasi mai costituiti da complessi PO e PPO ritmici continui a 3 Hz, come nelle Assenze del Piccolo Male. Alcuni Autori, infine, nel segnalare l'esordio e la ricorrenza di tale condizione tipicamente in età adulta e avanzata, hanno proposto la individuazione di una particolare forma di PMS, dipendente da fattori patologici di vario genere, caratterizzanti una sindrome specifica di questa età, diversa da quella del vero PMS tipico della infanzia e correlato con le Assenze del Piccolo Male.In questo lavoro viene proposta la descrizione di quindici casi esorditi alle varie età, che sembrano paradigmatici delle varie possibili espressioni cliniche del PMS, allo scopo di contribuire ad una migliore definizione nosografica di tale condizione epilettica. Sulla base di questa esperienza gli Autori sostengono che il cosiddetto PMS si configura come un tipo di crisi dell'Epilessia Generalizzata Idiopatica, che può insorgere in quasi tutte le età della vita e presentarsi isolato ovvero associato ad altre manifestazioni epilettiche, senza che di per sè possa caratterizzare una o più Sindromi età-dipendenti.
  相似文献   
38.
We describe a case of spontaneous splenic rupture occurred in a patient with acute lymphoblastic leukemia of Burkitt type before starting cytotoxic chemotherapy. Left hypochondrial pain radiating to the homolateral shoulder was the only clinical symptom. Emergency computed tomography showed splenic laceration and hemoperitoneum. The patient underwent immediate laparotomy with splenectomy and experienced an uneventful postoperative recovery. Eight days after surgery, chemotherapy could be administered and complete remission was achieved. Although spontaneous rupture of the spleen is rare in leukemia and related disorders, this diagnosis should be taken in account also when clinical symptoms are mild. Following immediate operative management, patients may completely recover and receive cytotoxic chemotherapy with substantial possibilities of achieving complete remission.  相似文献   
39.
We studied whether the administration of piracetam in acute, presumed ischemic stroke affects case fatality and functional outcome. The Cochrane Stroke Group strategy was used to evaluate all randomized controlled trials of patients with presumed ischemic stroke examined within 48 h; death and (when available) functional outcome were used as end points. Three studies were included; the most recent one contributed more than 97% of the data. There were 501 patients treated with piracetam and 501 controls. Piracetam was associated with a nonsignificant 31% increase in the odds of death (95% CI –5% to 81%). This result was due almost completely to the effect of the larger trial, which, however, reported that the difference in case fatality rate between piracetam and control disappeared after correcting for the imbalance in stroke severity between the two groups. Data on functional outcome were available only for the largest study, and no difference was reported. Data obtained from the manufacturer suggested a nonsignificant trend (–10%) towards reduction in dependency with piracetam (CI –33% to 20%); the proportions of patients dead or dependent in the two groups were the same. Relevant adverse effects were not reported. The evidence from this review does not support routine administration of piracetam in patients with acute ischemic stroke; however, since a possible beneficial effect cannot completely be ruled out, further controlled trials are warranted. Received: 31 August 1999/Received in revised form: 3 November 1999/Accepted: 25 November 1999  相似文献   
40.
Spontaneous esophageal perforation (Boerhaave's syndrome) remains a difficult diagnostic and management problem with controversial recommendations regarding its treatment. The clinical manifestations of the disease are variable, and may be misleading, thus delaying accurate recognition. On the other hand, in view of the rapid onset of severe complications, particularly mediastinitis, a prompt diagnosis is essential to a better prognosis, successful operative outcome and potential survival. A case of spontaneous perforation of the thoracic esophagus penetrating the left pleural space treated within 4 hours from admission to the Emergency Room, with minimal surgical intervention is presented. Despite negative chest X-ray, a thoracic TC showed a small right sided effusion with left sided hydropneumothorax, and the definitive diagnosis was obtained by contrast study with a water soluble medium which showed the leak communicating freely with the left pleural space. The patient underwent repair by thoracic approach, the rupture was closed with a primary suture without flap reinforcement and the pleural space drained with the placement of single chest thoracostomy tube. The recovery was uneventful. The analysis of this case report and of the appropriate literature reveals that a poor prognosis is correlated with the time elapsed between the perforation and treatment. In conclusion the importance of an early aggressive surgical treatment for the Boerhaave's syndrome is emphasized, because any perforation treated more than 24 hours after the onset of symptoms, irrespective of the procedure used, is associated with a significantly higher morbility and mortality.  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