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   15084篇
  免费   1196篇
  国内免费   284篇
耳鼻咽喉   163篇
儿科学   416篇
妇产科学   156篇
基础医学   767篇
口腔科学   230篇
临床医学   878篇
内科学   3326篇
皮肤病学   303篇
神经病学   1084篇
特种医学   245篇
外科学   1408篇
综合类   1335篇
预防医学   4558篇
眼科学   226篇
药学   531篇
  2篇
中国医学   52篇
肿瘤学   884篇
  2024年   17篇
  2023年   232篇
  2022年   484篇
  2021年   610篇
  2020年   573篇
  2019年   668篇
  2018年   719篇
  2017年   528篇
  2016年   504篇
  2015年   540篇
  2014年   1177篇
  2013年   1111篇
  2012年   865篇
  2011年   981篇
  2010年   815篇
  2009年   839篇
  2008年   791篇
  2007年   761篇
  2006年   626篇
  2005年   531篇
  2004年   363篇
  2003年   316篇
  2002年   265篇
  2001年   253篇
  2000年   216篇
  1999年   193篇
  1998年   162篇
  1997年   145篇
  1996年   112篇
  1995年   103篇
  1994年   90篇
  1993年   85篇
  1992年   102篇
  1991年   85篇
  1990年   84篇
  1989年   51篇
  1988年   59篇
  1987年   53篇
  1986年   39篇
  1985年   77篇
  1984年   49篇
  1983年   40篇
  1982年   35篇
  1981年   46篇
  1980年   27篇
  1979年   32篇
  1978年   20篇
  1977年   19篇
  1976年   25篇
  1975年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
TT virus (TTV) is a newly discovered virus from a patient with post-transfusion hepatitis. We investigated the frequency and pathogenesis of TTV infection in children. A semi-nested PCR assay was used to amplify TTV-DNA in serum samples from 254 ambulatory children without liver disease, 20 with hepatitis of unknown etiology, and 18 transfusion recipients or hemophiliacs. In positive samples, TTV-DNA was quantified by real-time quantitative PCR using a fluorescent probe. We detected TTV-DNA in 20% of children with hepatitis of unknown etiology, which was not statistically different from the 23% prevalence in ambulatory children. In transfusion recipients or hemophiliacs, the frequency was higher (50%) than that in ambulatory children (P = 0.01). Among ambulatory children, TTV-DNA was frequently detected in children with acute gastroenteritis (36%). TTV-DNA was detected in 10% of the infants under 6 months old, and 20% of the children from 7 to 12  months old. The prevalence was constant after the age of 1 year; however, the copy number of TTV-DNA was significantly higher in children under 1 year of age (mean: 105.4 versus 103.8 copies/ml, P= 0.008). Finally, TTV-DNA was quantified serially in three children with chronic hepatitis who were positive for TTV-DNA. The presence or amount of TTV-DNA was unrelated to the serum alanine aminotransferase level. These results indicate that TTV infection is common in children. The larger quantity of TTV-DNA in infants and the high prevalence of TTV in children of all ages suggest that TTV may be transmitted in early childhood. Its relationship to hepatitis is doubtful in children. Received: 8 April 1999  相似文献   
102.
BACKGROUND: The hemagglutination inhibition (HI) assay is a frequently used method to screen human sera for antibodies against influenza A viruses. Because HI has relatively poor sensitivity in detecting antibodies against avian influenza A strains, a more complicated microneutralization (MN) assay is often preferred. Recent research suggests that the sensitivity of the HI assay can be improved by switching from the traditionally used turkey, guinea pig, human, or chicken RBCs to horse RBCs. OBJECTIVE: To evaluate the performance of the horse RBC HI when screening for human antibodies against avian influenza types H3, H4, H5, H6, H7, H9, H11, and H12. STUDY DESIGN: We evaluated the reproducibility of horse RBC HI and its agreement with MN results using sera from people exposed or not exposed to wild and domestic birds. RESULTS: The horse RBC HI assay had high reliability (90%-100%) and good agreement with MN assay results (52%-100%). CONCLUSION: The horse RBC HI assay is reliable, less expensive, less complex, and faster than the MN assay. While MN will likely remain the gold standard serologic assay for avian viruses, the horse RBC HI assay may be very useful as a screening assay in large-scale epidemiologic studies.  相似文献   
103.
Summary The clinical courses of 214 patients with infective endocarditis treated between 1958 and 1987 at the First Medical Hospital of the University of Kiel (FRG) were analyzed retrospectively. A decrease in the incidence of endocarditis occurred during the 30-year observation period. The mean age of patients was 48 years, and men were more frequently affected than women. In the course of the investigation, a rise in isolated aortic valve disease was noted, whereas the number of patients with isolated involvement of the mitral valve and combined mitral-aortic valvular defects declined. Streptococci (57%) were the most frequent pathogens isolated; as opposed to their increase, the percentages ofStaphylococcus aureus and enterococci decreased. Otolaryngological, dentogenic and urogenital diseases were most frequently held to be responsible for the development of infective endocarditis. Prior cardiosurgical interventions became increasingly significant as a cause of the disease. In this connection, a rising percentage of endocarditis cases was linked with prosthetically replaced heart valves. Complications and concomitant symptoms of endocarditis included the development of heart failure, cerebral embolism and encephalitis, splenomegaly, and renal inflammation. Finally, the marked decrease in mortality contrasted with a simultaneous rise in the number of endocarditis cases achieving full recovery.  相似文献   
104.
The relationship between bladder cancer and alcohol consumption was investigated in a case-control study conducted in 546 patients (453 males and 53 females) with diagnoses of papillary urothelial carcinoma during 1978–1982 at La Paz hospital (Madrid), and an equal number of controls matched for age, sex and date of admission to the hospital. The results showed that the risk of bladder cancer does not increase with the intake of beer, wine and spirit beverages. However, a high risk of bladder cancer was associated with consumption of wine mixed with gaseosa (a refreshment beverage consisiting of carbonated water plus artificial sweeteners).  相似文献   
105.
Summary Clinically relevant events possibly attributable to drug exposure have been monitored prospectively over a period of six months in 27 general intensive care units. Fifty-four events attributed to drugs were reported in 51 patients during their stay in hospital, corresponding to an overall incidence of 1.35%. The behaviour of the physicians following attribution of the events to a prescribed drug is analyzed and discussed in detail with respect to its relationship to the quality and severity of the reaction, and the classes of drugs. Twenty-four of the 4537 monitored admissions during the six months were due to life-threatening emergencies linked to the administration of drugs (14) and radio-contrast media (10) (overall incidence 0.5%). While the clinical burden attributable to adverse drug reactions in Intensive Care Units appears to be relatively small, the analysis shows that there is ample room for a greater reduction in their incidence. Coordinators: Drs M. L. Farina and G. Tognoni, Istituto di Ricerche Farmacologiche Mario Negri, Milan; Dr F. Procaccio, Neurosurgical ICU, Ospedale Ca' Granda, Niguarda, Milan.Investigators: Drs G. Barusco, Rovigo; F. Bassi, Milan; L. Bianchetti, Torino; E. Carchietti, Udine; G. Chilloni, Reggio Emilia; G. Costantini, Savigliano (CN); P. Ferrero, Aosta; E. Geat, Trento; F. Gorgerino, Torino; A. Lusini, Empoli (FI); G. Mantovani, Ferrara; S. Marchi, Bologna; P. Marcovigi, Forli; G. Marraro, Merate (CO); F. Merlo, Vicenza; E. Pagni, Bagno a Ripoli (FI); R. Pellegrino, Cuneo; C. Peruselli, Milan; A. Piovesano, Pordenone; R. Rinaldo, Cremona; R. Ruggerini, Piacenza; S. Sammartino, Torino; A. Sartore, Cittadella (PD); A. Scaglioli, Carpi (MO); G. Scopa, Terni; G. Zeffiro, Treviso; P. Zuccoli, Parma  相似文献   
106.
Summary The unusual finding of an abnormal seasonal distribution of schizophrenic births, showing an excess of 10% in the winter or spring months and an equal deficit in the summer or autumn months, cannot be explained by artefacts. It has not yet been established whether the finding is specific to schizophrenia. We observed an excess of schizophrenic births of some 10% in March to May, significant at the 5% level, and a deficit of approximately the same size in June to August on the birth data of first-admission patients with the clinical diagnosis of schizophrenia. The data, obtained from the Mannheim Psychiatric Case Register, were compared with those of the Mannheim population and a control group matched by birth year and sex. The total population of mentally retarded children aged 7 to 16 years from the Mannheim population showed an excess of some 20% in April to June and an equal deficit in the last two quarters of the year, compared with the Mannheim population of the same birth years. The finding was not significant, but allowance must be made for the low case number of 415. We also compared 3409 first-admission patients with depressive syndromes (ICD 296 and 300.4) and 5615 first-admission patients with the diagnosis of neurosis and personality disorders (ICD 300–302, except 300.4, and 305–309) from the Mannheim Case Register with a control population and a parallel control group. Depressed males showed an excess of births in March to May, which was significant at the 1% level; the birth peak for females was smaller and not significant. The same findings were obtained for the category of neurosis and personality disorders, i.e. an excess of about 10% in March to May for males, significant at the 1% level, and a non-significant excess for females. Our findings are awaiting replication. Causal explanations will be discussed with great reservation. The procreational hypothesis, assuming those factors that lead to an equidirectional seasonal pattern of births with a slight deviation from the average of a year in the general population, to be reinforced in the disease categories mentioned, is regarded as the most simple and plausible explanation. It is based on the assumption that some of the parents of individuals suffering from schizophrenia, mental retardation or probably also some other mental disorders running from generation to generation, have a higher threshold in partner-seeking behaviour, which is overcome more easily in the summer months with the consequence of increased pregnancies.  相似文献   
107.
A multicenter prospective investigation was conducted in 17 teaching and general hospital in Italy to assess the efficacy of the care delivered to previously untreated patients with epilepsy. 175 cases were included and allocated to monotherapy. Only 112 cases completed the first year of follow-up. Of these, 59 (52.7%) were completely controlled and 53 (47.3%) had one or more seizure relapses. Controlied and uncontrolled patients were compared with respect to the main variables believed to influence non-responsiveness to standard therapy. The proportion of cases with relapses was significantly associated with the number of seizures reported before treatment was started. Selected seizure patterns (absences, myoclonic seizures) and prolonged disease duration were also reported more frequently among patients with recurrences. The implications of these findings are discussed with respect to drug response and prognosis of epilepsy.
Sommario Il presente studio consiste in una indagine prospettica multicentrica condotta in 17 centri ospedalieri italiani sulla efficacia del trattamento e sulla prognosi della malattia in pazienti con epilessia alla prima diagnosi. Dei 175 casi ammessi allo studio, 112 hanno completato il primo anno di osservazione. Di questi, 59 (52,7%) risultavano completamente controllati e 53 (47,3%) avevano presentato una o più crisi durante il follow-up. Le principali variabili ritenute responsabili di una insoddisfacente risposta al trattamento vennero quindi esaminate nei due gruppi. Il rischio di recidiva di crisi risultava significativamente correlato al numero di crisi presentate prima del trattamento. Inoltre, i pazienti con crisi nel follow-up presentavano una maggior durata di malattia o specifici tipi di crisi (assenze, crisi miocloniche). Il significato di tali dati è discusso in riferimento alle modalità di trattamento e agli altri fattori implicati nella prognosi dell'epilessia.
  相似文献   
108.
目的 了解昆明地区输血传播病毒(Transfusion Transnfited Virus,TTV)感染的流行情况。方法 对本科77例住院人的血清用聚合酶链反应(PCR)法进行TTV检测。结果 检出11例TTV阳性患。结论 昆明地区肝病病人中存在TTV感染,感染率低于国内外水平。感染途径包括非肠道途径和肠道途径。  相似文献   
109.
目的了解山东沿海地区常见风湿病的发病状况.方法选择东营、日照、威海和胜利石油管理局浅海钻井公司为调查点,调查4种风湿病发病情况.结果调查17044人.类风湿性关节炎粗患病率为0.6923%,标化患病率为0.3998%,各地区患病率差异显著,男女比例为1∶3.02.强直性脊椎炎粗患病率为0.1584%,标化患病率为0.1372%,男女比例为2∶1.系统性红斑性狼疮粗患病率为0.0528%,标化患病率为0.0465%,男女比例为1∶1.97.痛风粗患病率为0.0352%,标化患病率分别为0.0315%,男女比例2∶1.结论山东沿海地区的常见风湿病患病率较高.  相似文献   
110.
BackgroundPrevious studies about burns mortality are often exclusively based on hospital and burn centre data. National population-based reports on this topic are rather limited. The aim of this study was to analyse sex- and age-specific mortality rates of burns in Spain during the period 1979–2018.MethodsAge-standardised burns mortality rates were calculated from death records and mid-year population data were provided by the Spanish National Statistics Institute. Joinpoint regression analyses were used to identify significant points of change in trends over time and to compute average annual per cent change (AAPC). Age, period and cohort effects were also analysed.ResultsMortality due to burn injury decreased in both sexes between 1979 and 2018: from the first quinquennium of this period up to the last one age-adjusted mortality rates decreased from 1.37 to 0.49 per 100,000 in men and from 0.96 to 0.26 per 100,000 in women.ConclusionsBurns mortality rates in Spain have been decreasing during the last decades. Promotion of primary prevention measures should continue.  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