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   1405篇
  免费   94篇
  国内免费   10篇
耳鼻咽喉   4篇
儿科学   51篇
妇产科学   18篇
基础医学   243篇
口腔科学   34篇
临床医学   114篇
内科学   384篇
皮肤病学   28篇
神经病学   93篇
特种医学   22篇
外科学   115篇
综合类   3篇
一般理论   2篇
预防医学   91篇
眼科学   31篇
药学   91篇
中国医学   3篇
肿瘤学   182篇
  2024年   2篇
  2023年   9篇
  2022年   15篇
  2021年   49篇
  2020年   25篇
  2019年   45篇
  2018年   47篇
  2017年   30篇
  2016年   45篇
  2015年   39篇
  2014年   55篇
  2013年   75篇
  2012年   105篇
  2011年   137篇
  2010年   61篇
  2009年   69篇
  2008年   120篇
  2007年   116篇
  2006年   91篇
  2005年   90篇
  2004年   74篇
  2003年   77篇
  2002年   55篇
  2001年   13篇
  2000年   10篇
  1999年   10篇
  1998年   8篇
  1997年   9篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1989年   3篇
  1988年   1篇
  1986年   2篇
  1985年   3篇
  1984年   3篇
  1981年   2篇
  1979年   1篇
排序方式: 共有1509条查询结果,搜索用时 250 毫秒
71.
Human adenoviruses (AdVs) typically cause mild illnesses in otherwise healthy hosts. We investigated a pediatric outbreak of acute respiratory infection with fatal outcomes that occurred in Lisbon, Portugal, in 2004. Biological specimens were collected from 83 children attending two nurseries, a kinesiotherapy clinic, and the household of a nanny. Adenovirus infection was confirmed in 48 children by PCR and virus isolation. Most (96%) isolates were classified as being of subspecies B1. Phylogenetic analysis of fiber and hexon gene sequences revealed that most infants were infected with AdV serotype 3 (AdV3) strains. Infants attending one nursery harbored a new recombinant strain containing an AdV serotype 7 hexon and serotype 3 fiber (AdV7/3). Both the AdV3 and the AdV7/3 strains caused fatal infections. Two different serotype 3 strains were circulating in Lisbon in 2004, and the new AdV7/3 recombinant type originated from only one of those strains. These results demonstrate that recombination leads to the emergence of new adenovirus strains with epidemic and lethal potential.Human adenoviruses (HAdVs) have been associated with a wide spectrum of clinical diseases with respiratory and gastrointestinal symptoms (23, 32). Severe illness can occur in newborns, elderly individuals, and patients with underlying medical conditions. In otherwise healthy adults, infections caused by human adenoviruses do not represent a life-threatening clinical condition. Adenoviruses are characterized by a linear double-stranded DNA genome of 2 to 45 kbp that encodes 30 to 40 proteins (6). HAdV comprises 51 serotypes (HAdV-1 to HAdV-51), on the basis of type-specific antiserum-mediated neutralization of infectivity (10). The serotypes can be divided into seven species, named HAdV-A to HAdV-G, on the basis of hemagglutination inhibition and biochemical criteria (13). HAdV-B is further classified into subspecies B1 and B2, which use different cellular receptors for viral entry (29). These variants can be segregated by different geographic areas, time periods, and clinical conditions.Serotype identification is critical for epidemiological surveillance, the detection of new strains, assessment of treatment efficacy, and understanding the pathogenesis of HAdV. For example, acute respiratory disease is primarily caused by HAdV-B1 serotypes 3, 7, 16, and 21; HAdV-B2 serotypes 11 and 14; and HAdV-E serotype 4 (8, 23, 25, 28, 35, 38, 41). Respiratory infections caused by HAdV-B1 serotypes 3 and 7 (16) and HAdV-B2 serotype 14 (17) are potentially fatal. Neutralization tests are the classical reference method used for the typing of adenovirus and require virus isolation from infected organs or tissues (20). The main type-specific neutralizing epitope, the ɛ determinant, consists of loop 1 (L1) and loop 2 (L2) on the hexon protein, the major capsid protein and the most abundant structural protein (26). Cases of the failure of neutralization with the available antisera require extensive cross-neutralization studies to define a new HAdV type. To circumvent the practical problems associated with traditional serum neutralization studies, molecular methods for the typing of adenovirus have been established. Examples are restriction fragment length polymorphism (RFLP) analysis of adenoviral DNA (16), PCR-based assays (1, 36), and microarray-based methods (36). However, these methods cannot discriminate between all serotypes and do not allow detailed studies of molecular epidemiology and viral evolution to be performed.More recently, analysis of the nucleotide and amino acid sequences from different genes has shown that adenovirus species form three distinct phylogenetic clusters: HAdV-C belongs to cluster 1; HAdV-A and HAdV-F belong to cluster 2; and HAdV-B, HAdV-D, and HAdV-E belong to cluster 3 (6, 22). In addition, phylogenetic analysis of selected gene fragments has increasingly been used to classify human adenoviruses at the serotype and species levels (7, 19, 40), to detect cases of coinfection with multiple adenoviral species (36, 38), and to identify new recombinant strains formed between similar species (18, 37, 41) or different species (19). Finally, phylogenetic analysis has become an important tool in the epidemiological investigation of many disease outbreaks caused by adenovirus (11, 17, 27, 40, 41). In the present study, we have used epidemiological, virological, and molecular phylogenetic methods to investigate the causes and origin of a recent outbreak of acute respiratory infection in Lisbon, Portugal, that resulted in the deaths of two children.  相似文献   
72.
73.
Hepatic hemangioma is usually detected on a routine ultrasound examination because of silent clinical behaviour. The typical ultrasound appearance of hemangioma is easily recognizable and quickly guides the diagnosis without the need for further investigation. But there is also an entire spectrum of atypical and uncommon ultrasound features and our review comes to detail these particular aspects. An atypical aspect in standard ultrasound leads to the continuation of explorations with an imaging investigation with contrast substance [ultrasound/ computed tomography/or magnetic resonance imaging (MRI)]. For a clinician who practices ultrasound and has an ultrasound system in the room, the easiest, fastest, non-invasive and cost-effective method is contrast enhanced ultrasound (CEUS). Approximately 85% of patients are correctly diagnosed with this method and the patient has the correct diagnosis in about 30 min without fear of malignancy and without waiting for a computer tomography (CT)/MRI appointment. In less than 15% of patients CEUS does not provide a conclusive appearance; thus, CT scan or MRI becomes mandatory and liver biopsy is rarely required. The aim of this updated review is to synthesize the typical and atypical ultrasound aspects of hepatic hemangioma in the adult patient and to propose a fast, non-invasive and cost-effective clinical-ultrasound algorithm for the diagnosis of hepatic hemangioma.  相似文献   
74.
ABSTRACT

In 1978, Italy passed a law establishing the abolition of the mental hospital. Up to that time, the traditional asylums were still governed by the 1904 law that positioned psychiatry within the criminal justice system by assigning it the function of custodia (control, custody) rather than of cura (care). In the 1960s and 1970s, Italian psychiatrist Franco Basaglia initiated a movement of de-institutionalization of the mentally ill that revolutionized psychiatric care in Italy. It also had a deep impact on restructuring the psychiatric system in other European and Latin American countries. In this article, I discuss the different psychiatric practices and imaginaries that resulted from the movement of democratic psychiatry and Basaglia’s visions for a community-based and diagnosis-free care of the mentally ill. I ethnographically trace what I call the “Basaglia effect” in today’s psychiatric practices, and focus on ethnopsychiatry as a counter clinic that emerged from Basaglia’s legacy. I reflect on the frictions between care and cure that ethnopsychiatry re-articulates and works with in the context of contemporary migrations to Europe.  相似文献   
75.
High rate of recurrence after lobectomy for solitary thyroid nodule.   总被引:1,自引:0,他引:1  
OBJECTIVE: To evaluate the long-term outcome of patients treated by lobectomy for solitary thyroid nodule. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: 83 patients admitted with a clinical diagnosis of solitary thyroid nodule. INTERVENTIONS: Preoperative ultrasonography showed a solitary nodule in 32 patients and this finding was confirmed intraoperatively in 24 cases (77%). 59 patients with multinodular goitres were treated by total thyroidectomy and 24 with solitary nodule by lobectomy. MAIN OUTCOME MEASURES: Postoperative complications and freedom from nodule recurrence and/or parenchymal irregularity. RESULTS: One patient after lobectomy and 3 after total thyroidectomy developed temporary recurrent laryngeal nerve injury. Postoperative temporary hypoparathyroidism occurred in 13 patients (22%) after total thyroidectomy and in no patient after lobectomy (p = 0.02). Neither permanent recurrent laryngeal nerve injury nor permanent hypoparathyroidism occurred after either procedure. Among patients who underwent lobectomy, 6 had an adenoma and 18 had a nodular hyperplasia. At 4-year follow-up, the freedom rate from any thyroid nodule recurrence or parenchymal irregularity was 44.7%, and the freedom rate from nodular recurrence was 74%. Men tended to have a 4-year freedom rate from nodular relapse poorer than women (48% vs. 87%. p = 0.07). Nodular recurrence occurred in one patient operated on for an adenoma, and all the other recurrences occurred in patients with nodular hyperplasia. CONCLUSIONS: The mid-term freedom rate from thyroid nodule recurrence or parenchymal irregularity after lobectomy for solitary nodule of the thyroid is unsatisfactory. This observation calls for a better evaluation of long-term results after lobectomy for this condition and identification of risk factors predictive of recurrence. This would enable a more appropriate preoperative selection of patients undergoing lobectomy, indicating total thyroidectomy for those patients with solitary nodule at high risk of recurrence.  相似文献   
76.
Acrodermatitis continua of Hallopeau (ACH) consists of a relapsing pustular eruption of the distal portions of hands and feet. We described a case of a 9-year-old boy affected by ACH, successfully treated with targeted ultraviolet B 311 nm phototherapy, which seems to be an effective and safe therapy for this condition.  相似文献   
77.
78.
79.
PURPOSE: The aim of this study was to define the risk of second cancer in nongastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT). EXPERIMENTAL DESIGN: We considered for the analysis 157 patients with a confirmed histology of marginal zone B-cell lymphoma of MALT, presenting with a clinically prevalent extranodal site of disease, except for stomach. All patients came from two hematologic institutions of Northern Italy. We compared the occurrence of second cancer with respect to the general population by calculating the standardized incidence ratio, with the age- and sex-specific incidence rates of a cancer registry of Northern Italy (Lombardia) as a reference. RESULTS: A history of solid neoplasia was present in 29 (18%) patients for a total number of 30 neoplasms: 25 solid tumors, 2 hematologic diseases (1 Hodgkin's lymphoma and 1 essential thrombocythemia), and 3 nonmelanoma in situ skin cancers. In 4 patients, the site of cancer and lymphoma was the same. In 21 cases the solid tumor preceded the MALToma, in 3 the neoplasm was concomitant, whereas in 6 it was subsequent. For the entire group, the standardized incidence ratio of an additional malignancy was 0.8 [95% confidence interval (95% CI), 0.55-1.17; P = 0.2]. After excluding nonmelanoma skin cancer, the standardized incidence ratio of a second tumor was 0.75 (95% CI, 0.5-1.12; P = 0.2). After excluding all previous malignancies, the standardized incidence ratio of a second cancer was 1.32 (95% CI, 0.69-2.55; P = 0.4). The comparison of risks between males and females was not significant in each group analysis. CONCLUSIONS: Patients with nongastric MALT lymphomas are not at increased risk for other neoplasms compared with the general population of the same geographic area.  相似文献   
80.
Vanadyl as a catalyst of human lipoprotein oxidation   总被引:2,自引:0,他引:2  
Lipoprotein oxidation, which is relevant to atherogenesis, can be induced by redox-active transition metals, such as copper. Vanadium is a metal usually used as vanadyl to improve metabolic control in diabetic patients; given its redox-active properties, we have investigated possible oxidative effects of the metal on lipoproteins from healthy and diabetic subjects. Beginning from 10 microM, vanadyl, but not vanadate, induced oxidation of the non-HDL fraction, which was inhibited by EDTA, butylated hydroxytoluene and Vitamins E and C, but not by mannitol, SOD and catalase. Differently from copper, vanadyl could oxidize directly lipoprotein lipids, although it showed a lower oxidant activity against critical tryptophan residues of the lipoprotein protein moiety. Moreover, the non-HDL fraction of diabetic patients was more susceptible to vanadyl-dependent oxidation than that of controls. Thus, vanadium, in its reduced form which may be used in humans, can oxidize the non-HDL fraction through oxidative effects exerted especially on lipoprotein lipids; the specific pro-oxidant activity of vanadyl is more evident with lipoproteins of diabetic patients. Given also the tissue accumulating capacity of vanadium conceivably in a reduced form, its prolonged administration to humans, especially to diabetic patients without adequate antioxidant supplementation, needs caution.  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