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   5084篇
  免费   238篇
  国内免费   67篇
耳鼻咽喉   161篇
儿科学   169篇
妇产科学   155篇
基础医学   548篇
口腔科学   192篇
临床医学   436篇
内科学   1065篇
皮肤病学   117篇
神经病学   273篇
特种医学   207篇
外国民族医学   1篇
外科学   840篇
综合类   170篇
现状与发展   1篇
一般理论   1篇
预防医学   349篇
眼科学   98篇
药学   309篇
中国医学   61篇
肿瘤学   236篇
  2023年   33篇
  2022年   67篇
  2021年   120篇
  2020年   63篇
  2019年   91篇
  2018年   127篇
  2017年   102篇
  2016年   110篇
  2015年   136篇
  2014年   179篇
  2013年   197篇
  2012年   319篇
  2011年   326篇
  2010年   194篇
  2009年   118篇
  2008年   223篇
  2007年   287篇
  2006年   265篇
  2005年   313篇
  2004年   210篇
  2003年   213篇
  2002年   236篇
  2001年   161篇
  2000年   179篇
  1999年   165篇
  1998年   41篇
  1997年   34篇
  1996年   27篇
  1995年   34篇
  1994年   21篇
  1993年   15篇
  1992年   82篇
  1991年   72篇
  1990年   64篇
  1989年   53篇
  1988年   42篇
  1987年   50篇
  1986年   54篇
  1985年   43篇
  1984年   32篇
  1983年   22篇
  1979年   20篇
  1975年   14篇
  1974年   27篇
  1973年   18篇
  1971年   21篇
  1970年   25篇
  1969年   16篇
  1968年   13篇
  1967年   13篇
排序方式: 共有5389条查询结果,搜索用时 15 毫秒
121.
Aztreonam and cefotaxime were compared in 44 cirrhotic patients who had 52 episodes of gram-negative spontaneous peritonitis. Patients were randomized into two therapeutic groups of similar characteristics. Group A (28 episodes) received 0.5 gm of aztreonam every 8 hr, and group B (24 episodes) received 1 gm of cefotaxime every 6 hr, for a planned 14-day period. Peak and trough serum and ascitic fluid levels of both antibiotics were several times higher than the minimum inhibitory concentrations of causative microorganisms. Eleven patients (21%) died within the first 48 hr after beginning therapy, which included seven in the aztreonam group and four in the cefotaxime group. In the remaining patients, signs and symptoms of infection were promptly controlled, and ascitic fluid cultures became negative after 48 hr in all cases, except in one patient from the aztreonam group, who was a clinical failure. Two patients from the aztreonam group and one from the cefotaxime group relapsed after treatment. The overall mortality rate was 50%, which was lower than classically reported: 12 patients (43%) died in the aztreonam group, and 14 (58%) died in the cefotaxime group (p = 0.265, NS). Hepatorenal syndrome and digestive tract hemorrhage were the most frequent causes of death occurring after the first 48 hr of treatment. Streptococcal superinfections developed in three patients (14.2%) in the aztreonam group. We conclude that both antibiotics at the low doses used in this study are similarly well tolerated and effective in controlling this infection. Because the use of aztreonam as the initial empirical treatment requires a concomitant antibiotic against gram-positive infections and the possibility of streptococcal superinfections, cefotaxime seems to be a more advantageous therapeutic alternative for this patient population.  相似文献   
122.
Nephrotic syndrome is infrequently complicated with appearance of acute renal failure and minimal change disease is the glomerulopathy more usually involved. Pathogenesis is unclear and three possible mechanisms it has been proposed to explain the decrease of glomerular filtration rate: a severe reduction of glomerular permeability, the presence of acute tubular necrosis or an increased intrarenal pressure related with interstitial oedema. Here we present a 36 years-old-male with a nephrotic syndrome caused by focal and segmental glomerulosclerosis who developed an anuric acute renal failure. Renal function did not change despite oedema removal with haemodialysis and only after corticosteroid and cyclophosphamide therapy introduction we observed a rapid recovery of urinary output and resolution of acute renal failure. Renal biopsy did not show signs of tubular damage or obstruction with proteins nor significant interstitial oedema. Therefore, in this case we think acute renal failure was caused by a severe reduction in glomerular ultrafiltration rate and steroids were the effective treatment that allowed recovery of renal function.  相似文献   
123.
Transdermic administration by electroporation has developed over recent years for applying drugs in a variety of pathological processes. However, mechanisms are still not finally settled. India ink was applied to the backs of guinea pigs and for the transdermic transport short, high-voltage pulses (TDES, Dencort Dell) were administrated. Punch biopsies (4 mm) immediately taken after 24, 48, 72, 96 and at 26 days were studied by light and electronic microscopy. The ultrastructural characteristics and image pigment particles were reported. Particles of India ink were observed in the stratum corneum and in the epidermic keratinocytes of samples studied immediately after treatment. Particles were also seen in the epidermic and folicular keratinocytes, and in the papillary and reticular dermis (among collagen fibers, vessel walls, and macrophages) in all the subsequent biopsies; but not in the controls, which were conducted with electromagnetic waves alone. No tissue alterations were observed. The efficacy and noninvasive nature of electroporation for the transdermic administration of macromolecules is confirmed.  相似文献   
124.
Journal of Neurology - The epileptogenicity of recombinant tissue-plasminogen activator (rt-PA) has been suggested, but seizures were not evaluated in randomised controlled trials. To evaluate...  相似文献   
125.

Aim

To investigate the usefulness of humerus measurement for sex determination in a sample of medieval skeletons from the Eastern Adriatic Coast. Additional aim was to compare the results with contemporary female population.

Methods

Five humerus measurements (maximum length, epicondylar width, maximum vertical diameter of the head, maximum and minimum diameter of the humerus at midshaft) for 80 male and 35 female medieval and 19 female contemporary humeri were recorded. Only sufficiently preserved skeletons and those with no obvious pathological or traumatic changes that could affect the measurements were included. For ten samples, analysis of DNA was performed in order to determine sex using amelogenin.

Results

The initial comparison of men and women indicated significant differences in all five measures (P < 0.001). Discriminant function for sex determination indicated that as much as 85% of cases could be properly categorized, with better results in men (86%) than women (80%). Furthermore, the comparison of the medieval and contemporary women did not show significant difference in any of the measured features. Sex results obtained by anthropological and DNA analysis matched in all 10 cases.

Conclusion

The results indicate that humerus measurement in Croatian medieval population may be sufficient to determine the sex of the skeleton. Furthermore, it seems that secular changes have not substantially affected contemporary population, suggesting that the results of this study are transferable to contemporary population as well.Once the skeletal remains are uncovered, anthropologists initially aim to reconstruct the biological profile of the person, which includes sex, age, and height estimation. During the reconstruction process, numerous issues may arise, including bone fragmentation and poor preservation of skeletal remains, coupled with the complexity of human skeleton (1,2). Sex determination is one of the first and basic steps of assessing the biological profile. Although the analysis of DNA is the most reliable method for sex determination (3), it is also the most expensive and time consuming method, which can also be hindered by local conditions. This may especially be true in cases of poor preservation of the remains, inhibitors effects, or a small amount of extracted DNA from the sample.In absence of DNA results, skeletal remains can be used to infer subject’s sex via two methods, morphological and anthropometric. The morphological approach is based on the examination of the bones that show the strongest sexual dimorphism, principally the skull and the pelvis (4). However, this method is not always reliable, especially if the skull is fragmented or incomplete. Age can also affect the results, especially in elderly women, in which morphological characteristics of the skull tend to resemble those of men (5). Although morphological methods are very important for a preliminary sex assessment, they additionally rely on the experience of the examiner and are therefore rather subjective and unreliable.The second approach is based on anthropometric analysis, which relies on the bone measurements. The main analytic approach is based on discriminant function analysis, which attempts to classify subjects into each of the sexes, by using either one or more bones (6). This kind of analysis is a very important quantitative method (7) for sex determination as it reduces the subjectivity of the examiner (2,4,8). So far, only a few such studies have been published using Croatian bone samples. These include medieval and contemporary femurs and tibias (8-11) and medieval and contemporary mandibles and teeth (6,12). Such studies are important, since clear differences were observed in different populations (13-15), making this a locally-specific feature that requires the development of regional standards, applicable for local population (16).Besides already used femurs and tibias, humerus is another long bone from the body that is presumably informative for sex determination. This idea was initially derived from the empirical investigations of the skeletal remains, and further supported by the previously reported sexual dimorphism of humeri (7,17), even in cases of severe bone fragmentation (18). Furthermore, such location-specific results may be of interest in modern forensics as well, since observed changes in the skeleton marked predominantly by the increase in height (19), appear to be proportional, with no indication of sexual dimorphism in ancient and modern samples (20). Therefore, the aim of this study was to investigate the possibility to determine the sex of the subject based on anthropometric analysis of humeri measures.  相似文献   
126.
Ouarhache  Maryem  Marquet  Sandrine  Frade  Amanda Farage  Ferreira  Ariela Mota  Ianni  Barbara  Almeida  Rafael Ribeiro  Nunes  Joao Paulo Silva  Ferreira  Ludmila Rodrigues Pinto  Rigaud  Vagner Oliveira-Carvalho  Cândido  Darlan  Mady  Charles  Zaniratto  Ricardo Costa Fernandes  Buck  Paula  Torres  Magali  Gallardo  Frederic  Andrieux  Pauline  Bydlowsky  Sergio  Levy  Debora  Abel  Laurent  Cardoso  Clareci Silva  Santos-Junior  Omar Ribeiro  Oliveira  Lea Campos  Oliveira  Claudia Di Lorenzo  Nunes  Maria Do Carmo  Cobat  Aurelie  Kalil  Jorge  Ribeiro  Antonio Luiz  Sabino  Ester Cerdeira  Cunha-Neto  Edecio  Chevillard  Christophe 《Journal of clinical immunology》2021,41(5):1048-1063
Abstract

Cardiomyopathies are an important cause of heart failure and sudden cardiac death. Little is known about the role of rare genetic variants in inflammatory cardiomyopathy. Chronic Chagas disease cardiomyopathy (CCC) is an inflammatory cardiomyopathy prevalent in Latin America, developing in 30% of the 6 million patients chronically infected by the protozoan Trypanosoma cruzi, while 60% remain free of heart disease (asymptomatic (ASY)). The cytokine interferon-γ and mitochondrial dysfunction are known to play a major pathogenetic role. Chagas disease provides a unique model to probe for genetic variants involved in inflammatory cardiomyopathy.

Methods

We used whole exome sequencing to study nuclear families containing multiple cases of Chagas disease. We searched for rare pathogenic variants shared by all family members with CCC but absent in infected ASY siblings and in unrelated ASY.

Results

We identified heterozygous, pathogenic variants linked to CCC in all tested families on 22 distinct genes, from which 20 were mitochondrial or inflammation-related – most of the latter involved in proinflammatory cytokine production. Significantly, incubation with IFN-γ on a human cardiomyocyte line treated with an inhibitor of dihydroorotate dehydrogenase brequinar (enzyme showing a loss-of-function variant in one family) markedly reduced mitochondrial membrane potential (ΔψM), indicating mitochondrial dysfunction.

Conclusion

Mitochondrial dysfunction and inflammation may be genetically determined in CCC, driven by rare genetic variants. We hypothesize that CCC-linked genetic variants increase mitochondrial susceptibility to IFN-γ-induced damage in the myocardium, leading to the cardiomyopathy phenotype in Chagas disease. This mechanism may also be operative in other inflammatory cardiomyopathies.

  相似文献   
127.
Emotional dysregulation is a key symptom in participants with personality disorders. The Emotional Regulation Questionnaire (ERQ) has been studied with nonclinical samples; however, it is necessary to confirm the factorial structure of the ERQ in participants with personality disorders. The aims of the present study were to confirm the factorial structure of the Spanish version of the ERQ and analyse its psychometric properties as well as the association between the ERQ and the Borderline Symptoms List (BSL-23) and the Difficulties in Emotion Regulation Scale (DERS). The overall sample was composed of 250 patients with personality disorders, of whom 195 met the criteria for borderline personality disorder. Confirmatory factor analysis was conducted. The two-factor model showed an acceptable fit, similar to the original structure, in the participants with personality disorders and with borderline personality disorder. Cognitive reappraisal was negatively correlated with the DERS and BSL-23, and expressive suppression was positively correlated with the BSL-23. The ERQ is a reliable and valid instrument to evaluate emotional dysregulation in participants with personality disorders and participants with borderline personality disorder.  相似文献   
128.
The clinic usage of cisplatin, an anticancer drug, is limited due to it has many side effects in many systems and organs. In this context, it was aimed to investigate the protective effect of hesperidin, a citrus flavonoid, on testicular and spermatological damages induced by cisplatin in rats. The rats were randomly divided into four groups. The first group was kept as a control. In the second groups, cisplatin was given at the single dose of 7 mg kg?1 intraperitoneally. In the third group, hesperidin was orally administered at the dose of 50 mg/kg day?1 for 14 days. In the fourth group, cisplatin and hesperidin were given together at the same doses. Cisplatin treatment caused significant reductions enzymatic (SOD, CAT and GPx) and nonenzymatic (GSH) antioxidants and significant induction level of TBARS. In addition, cisplatin treatment caused decreased sperm motility, epididymal sperm concentration, increased abnormal sperm rate and histopathological damage. In contrast, hesperidin treatment significantly attenuated the harmful effects. In conclusion, this study clearly demonstrated that hesperidin has protective effects on cisplatin‐induced reproductive system toxicity depending on its antioxidant properties. Thus, it is thought that hesperidin may be useful against cisplatin toxicity in patients with cancer in terms of reproductive system.  相似文献   
129.
130.
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