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   1910篇
  免费   154篇
  国内免费   6篇
耳鼻咽喉   39篇
儿科学   84篇
妇产科学   89篇
基础医学   324篇
口腔科学   40篇
临床医学   169篇
内科学   391篇
皮肤病学   24篇
神经病学   340篇
特种医学   22篇
外科学   174篇
综合类   8篇
预防医学   129篇
眼科学   31篇
药学   69篇
肿瘤学   137篇
  2024年   5篇
  2023年   27篇
  2022年   42篇
  2021年   85篇
  2020年   55篇
  2019年   79篇
  2018年   77篇
  2017年   69篇
  2016年   75篇
  2015年   69篇
  2014年   96篇
  2013年   98篇
  2012年   150篇
  2011年   155篇
  2010年   74篇
  2009年   86篇
  2008年   111篇
  2007年   132篇
  2006年   123篇
  2005年   103篇
  2004年   85篇
  2003年   81篇
  2002年   62篇
  2001年   6篇
  2000年   6篇
  1999年   10篇
  1998年   15篇
  1997年   12篇
  1996年   5篇
  1995年   7篇
  1994年   8篇
  1993年   15篇
  1992年   5篇
  1991年   7篇
  1990年   4篇
  1989年   4篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   5篇
  1981年   2篇
  1978年   2篇
  1977年   3篇
  1975年   1篇
  1974年   1篇
  1972年   2篇
  1968年   1篇
  1964年   2篇
排序方式: 共有2070条查询结果,搜索用时 15 毫秒
131.
A 30‐year‐old man presented with livid‐red to brownish, strongly infiltrated, and markedly elevated plaques of 1–5 cm in diameter with fine scaling on the buttocks, lower trunk, and lower extremities of 2 years’ duration ( Figs 1 and 2 ). Complete blood cell count and routine serum chemistry were within normal limits, with the exception of erythrocyte sedimentation rates of 18 and 36 mm in the first and second hour, respectively, and a C‐reactive protein level of 8.1 mg/dL. Serum angiotensin converting enzyme (ACE) levels were elevated at 90 U/L (normal values, 18–60 U/L), while serum lysozyme levels, vitamin D, and calcium were normal. The patient presented an anergic reaction to the seven antigens of Multitest Merieux.
Figure Figure 1  Open in figure viewer PowerPoint Livid‐red to brownish, deeply infiltrated, and markedly elevated plaques on the lower trunk and buttocks  相似文献   
132.
133.
Calcium, iron, copper, and zinc concentrations in muscle were measured in vivo by x-ray spectrometry (XRS). The undersurface of the tongue was examined in cardiomyopathic and in normal hamsters. Values were compared to in-vitro analyses of various muscles from the same groups of animals using XRS and chemical analysis. Blood tests as well as histologic and histometric examinations were also performed. The correlated results show that XRS is a relatively sensitive and practical method for measuring chemical elements in muscle, and that it could be developed into a useful clinical test in certain neuromuscular and myocardial diseases. An interesting incidental finding was that, though all the examined muscles of myopathic animals had pathologic changes, only the tongue and myocardium, which are composed exclusively of red fibers, showed excessive calcium accumulation. This suggests either that the basic genetic aberration is not directly related to the oxidative metabolism, or that white muscles have a more efficient system for dealing with calcium overload.  相似文献   
134.
Symptomatic urinary tract infections following voiding cystourethrography   总被引:2,自引:2,他引:0  
The objective of this study was to assess the frequency of symptomatic urinary tract infections (UTIs) following voiding cystourethrography (VCUG) while using prophylactic antibiotics. Medical records of 421 patients who underwent a VCUG during a period of 4 years were reviewed. Three hundred forty-nine had a VCUG following a febrile UTI, and 72 had the test for evaluation of hydronephrosis. All received prophylactic antibiotics and were evaluated within 7–10 days following the VCUG. One hundred seventy-two children (41%) had an abnormal VCUG. Seven of 421 children (1.7%) had symptoms suggestive of UTI. Two had culture negative pyuria; one had Escherichia Coli UTI, and four had Pseudomonas aeruginosa UTI. On multivariate logistic regression analysis, the risk factors contributing to the development of UTI following VCUG were the presence of vesicoureteral reflux (VUR) and its severity (odds ratio [OR] 2.52; 95% confidence interval [CI] 2.24, 2.83, p =0.001; and OR 2.32; 95% CI 2.05,2.62, p =0.04, respectively). The incidence of VCUG-induced UTI in children receiving prophylactic antibiotic therapy is low. There is a relatively high rate of Pseudomonas UTI, especially in children with moderate to severe reflux. We recommend that children with symptoms suggesting a UTI following a VCUG should be treated for Pseudomonas aeruginosa pending culture results.  相似文献   
135.
OBJECTIVES: Crohn's disease (CD) has been reported to be more frequent among non-Ashkenazi Jewish patients suffering from familial Mediterranean fever (FMF). Interestingly, functional similarities between the CD susceptibility gene (NOD2/CARD15) and the FMF gene (MEFV) have been described: both belong to the death domain containing protein family, important in the regulation of apoptosis, cytokine processing and inflammation. AIMS: To investigate the prevalence of MEFV mutations in Jewish non-Ashkenazi CD patients and its putative effect on CD presentation. METHODS: Germline DNA of 105 Israeli CD patients of non-Ashkenazi and mixed Ashkenazi-non-Ashkenazi ethnic background was analyzed for three most common MEFV mutations: M694V, V726A, and E148Q. Five patients (4.7%) with a clinical diagnosis of FMF were included. Data obtained from each patient included: age of onset, disease location, and behavior, the presence of extraintestinal manifestations of CD and therapeutic regimens. RESULTS: The overall prevalence of mutation carriers among non-FMF-CD patients was 13% (13/100). A stricturing disease pattern was observed in 56% (10/18) of all carriers, FMF-CD, and non-FMF-CD patients, and in 25% (22/87) of noncarriers (OR: 3.7, 95% CI: 1.3-10.5, p= 0.015). The prevalence of fistulas was comparable in both groups. Extraintestinal manifestations were significantly more frequent among carriers than noncarriers (65%vs 32%, OR 3.9, 95% CI = 1.3-11.5, p= 0.015). No differences were observed in disease location and disease severity. CONCLUSIONS: MEFV mutations are not associated with CD susceptibility, yet the presence of these mutations appears to be associated with a stricturing disease pattern and extraintestinal disease manifestations of CD.  相似文献   
136.
OBJECTIVES: To investigate the relation between subjective and objective performance-based measures of functional status in persons with multiple sclerosis (MS), and to compare their performance with healthy controls. DESIGN: A between-groups design, using a correlational approach to examine the relation between objective and subjective measures of functional capacity. SETTING: Outpatient rehabilitation research institution. PARTICIPANTS: Seventy-four subjects with clinically definite MS and 35 healthy controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Executive Function Performance Test (EFPT), Functional Assessment of Multiple Sclerosis (FAMS), and Functional Behavior Profile (FBP). RESULTS: MS participants reported more difficulties performing functional tasks than did the healthy controls. MS participants also performed significantly worse on the EFPT than healthy controls. However, all correlations between subjective and objective functional measures were nonsignificant. After controlling for depressive symptomatology, EFPT performance was significantly associated with FBP scores, but not FAMS scores. CONCLUSIONS: The lack of association between objective performance-based measures and subjective self-report measures of functional activities is a challenge to outcomes measurement and has implications for assessment of functional performance. Results are discussed in terms of the different dimensions that these tools are measuring and their respective strengths and limitations.  相似文献   
137.
BACKGROUND: Measures of perceived coercion at psychiatric hospital admission have been developed. We aimed to investigate predictors of perceived coercion in subjects admitted to psychiatric hospital in the UK, and to test the hypothesis that high perceived coercion at admission predicts poor engagement with community follow-up. METHOD: A cohort of consecutively admitted subjects were interviewed at admission and before discharge, and were followed prospectively for 10 months. Service use and compliance with care were rated from case notes and by clinicians. RESULTS: One hundred interviews were obtained from 118 consecutive admissions (85%). Compulsory admission was strongly associated with perceived coercion, but one-third of voluntary patients felt highly coerced, and two-thirds were not certain they were free to leave hospital. Greater age, less insight, and non-white ethnicity were associated with high perceived coercion. Perceived coercion did not predict engagement with follow-up. CONCLUSIONS: Services recognise provision of care in the least restrictive setting as a key objective. Perceived coercion should be regarded as an important outcome measure in service evaluation.  相似文献   
138.
It is well established that the conversion of PrP(C) to PrP(Sc) is the key event in prion disease biology. In addition, several lines of evidence suggest that glycosaminoglycans (GAGs) and in particular heparan sulfate (HS) may play a role in the PrP(C) to PrP(Sc) conversion process. It has been proposed that PrP(Sc) accumulation in prion diseases may induce aberrant activation of lysosomal activity, which has been shown to result in neurodegeneration in a number of diseases, especially lysosomal storage disorders. Among such diseases, only the ones resulting from defects in GAGs degradation are accompanied by secretion of large amounts of GAG metabolites in urine. In this work, we show that GAGs are secreted in the urine of prion-infected animals and humans, and surprisingly, also in the urine of mice ablated for the PrP gene. We hypothesize that both the presence of PrP(Sc) or the absence of PrP(C) may alter the metabolism of GAGs.  相似文献   
139.
BACKGROUND: Intrauterine growth retardation (IUGR) is a major cause of short stature in childhood. Most but not all children experience catch-up growth by 2 years of age. METHODS: We investigated the endocrine profile (thyroid function, prolactin, cortisol, C-peptide and insulin-like growth factor-I [IGF-IJ levels) of 57 children with IUGR, aged 2-10 years, and compared it with 30 controls whose birth weight was appropriate-for-gestational-age. RESULTS: The hormonal profile for both groups was similar for thyroid hormones, prolactin, C-peptide and IGF-I. Cortisol levels were significantly lower in the IUGR group compared to controls (p <0,05). When the IUGR group was divided into 'catch-up' growth and 'non-catch-up' subgroups, the latter had significantly lower IGF-I levels (p <0.001). CONCLUSIONS: Lower cortisol levels in children born with IUGR may reflect impaired function of the hypothalamic-pituitary-adrenal axis associated with this condition. The significantly lower IGF-I levels of the 'non-catch-up' subgroup may be involved in their failure to grow.  相似文献   
140.
Gastrointestinal nematode infection is known to alter host T cell activation and has been used to study immune and inflammatory reactions in which nitric oxide (NO) is a versatile player. We previously demonstrated that Trichinella spiralis infection inhibits host inducible NO synthase (NOS-2) expression. We now demonstrate that (i) an IL-4 receptor alpha-subunit (IL-4Ralpha)/Stat6-dependent but T cell-independent pathway is the key for the nematode-induced host NOS-2 inhibition; (ii) endogenous IL-4 and IL-13, the only known IL-4Ralpha ligands, are not required for activating the pathway; and (iii) treatment of RAW264.7 cells with parasite-cultured medium inhibits NOS-2 expression but not cyclooxygenase 2 expression. We propose that a yet-unidentified substance is released by the nematode during the host-parasite interaction.  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