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   1298篇
  免费   86篇
  国内免费   15篇
耳鼻咽喉   7篇
儿科学   63篇
妇产科学   31篇
基础医学   149篇
口腔科学   19篇
临床医学   106篇
内科学   362篇
皮肤病学   9篇
神经病学   133篇
特种医学   58篇
外科学   183篇
综合类   1篇
预防医学   44篇
眼科学   9篇
药学   113篇
中国医学   1篇
肿瘤学   111篇
  2024年   1篇
  2023年   24篇
  2022年   36篇
  2021年   38篇
  2020年   21篇
  2019年   37篇
  2018年   31篇
  2017年   25篇
  2016年   51篇
  2015年   50篇
  2014年   61篇
  2013年   69篇
  2012年   120篇
  2011年   111篇
  2010年   47篇
  2009年   49篇
  2008年   67篇
  2007年   105篇
  2006年   81篇
  2005年   87篇
  2004年   75篇
  2003年   67篇
  2002年   39篇
  2001年   7篇
  2000年   9篇
  1999年   4篇
  1998年   9篇
  1997年   9篇
  1996年   13篇
  1995年   3篇
  1994年   3篇
  1993年   6篇
  1992年   4篇
  1991年   1篇
  1989年   2篇
  1988年   2篇
  1987年   7篇
  1986年   5篇
  1985年   2篇
  1984年   4篇
  1983年   2篇
  1982年   3篇
  1981年   5篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
排序方式: 共有1399条查询结果,搜索用时 13 毫秒
51.
52.
Interferon-gamma-inducible Protein-10 (IP-10) is supposed to play a role in Alzheimer's disease (AD) development, as demonstrated by increased levels in cerebrospinal fluid from patients with AD. A mutation scanning of IP-10 exonic region was carried out in 10 patients with AD and 10 age-matched controls, demonstrating the presence of two previously reported single nucleotide polymorphisms (SNPs) in exon 4 (G-->C and T-->C) as well as a novel SNP in exon 2 (C-->T). Exon 4 G-->C and T-->C allelic variants were next evaluated in a population of 279 AD patients and 251 controls, in order to determine whether their presence could influence the susceptibility towards the development of the disease. These two SNPs were in complete linkage disequilibrium. No differences in haplotype frequencies were found in AD patients as compared with controls, even stratifying according to the presence of Apolipoprotein E varepsilon4 allele, gender or age at onset. A new protocol was developed to easily determine the C-->T SNP in exon 2. A preliminary analysis revealed a very low frequency of this allelic variant (1%). Therefore, the complete association study was not carried out because the size of our population was not sufficient to draw reliable conclusions. According to these results, IP-10 does not seem to be a risk factor for AD. However, a novel rare polymorphism has been identified, which could exert a role in AD susceptibility. Thus, further studies on larger populations are needed before confidently excluding IP-10 as a susceptibility gene for AD.  相似文献   
53.
The Phoenix system (Becton Dickinson Diagnostic Systems, Sparks, MD) was evaluated for identification (ID) to the species level of streptococci and enterococci. Two hundred clinical isolates were investigated: beta-hemolytic streptococci (n = 50), Streptococcus pneumoniae organisms (n = 46), viridans group streptococci (n = 31), Enterococcus faecium (n = 36), Enterococcus faecalis (n = 25), and other catalase-negative cocci (n = 12). The API system (bioMérieux, Marcy l'Etoile, France) was used as a comparator. Molecular methods (sequencing of 16S rRNA and zwf and gki genes and ddl gene amplification) were used to investigate discordant results. Upon resolution of discrepancies, correct species ID was achieved by the Phoenix system for 121/129 (93.8%) streptococci and 63/70 (90.0%) enterococci. Excellent results were obtained for S. pneumoniae (45/45) and beta-hemolytic streptococci (49/50). With regard to viridans streptococci, the accuracy of the Phoenix system was 83.9%. Among the latter organisms, the best performance was obtained with isolates of the Streptococcus sanguinis group and Streptococcus anginosus group; problems were instead encountered with the Streptococcus mitis group. Four E. faecium and three E. faecalis isolates were misidentified as Enterococcus casseliflavus/Enterococcus gallinarum or Enterococcus durans. Thus, these isolates were identified only at the genus level. Compared with commercially available systems, the Phoenix system appears a reliable diagnostic tool for identifying clinically relevant streptococci and enterococci. The SMIC/ID-2 panel proved particularly effective for beta-hemolytic streptococci and pneumococci.  相似文献   
54.
Abnormal amyloid-β (Aβ) production and deposition is believed to represent one of the main causes of Alzheimer's disease (AD). γ-Secretase is the enzymatic complex responsible for Aβ generation from its precursor protein. Inhibition or modulation of γ-secretase represents an attractive therapeutic approach. CHF5074 is a new γ-secretase modulator that has been shown to inhibit brain plaque deposition and to attenuate memory deficit in adult AD transgenic mice after chronic treatment. To date, it is not known whether the positive behavioral effects of this compound also occur in young transgenic mice without plaque deposition. Here, we evaluated the effects of acute and subchronic treatment with CHF5074 on contextual and recognition memory and on hippocampal synaptic plasticity in plaque-free Tg2576 mice. We found that at 5 months of age, contextual memory impairment was significantly attenuated after acute subcutaneous administration of 30 mg/kg CHF5074. At 6 months of age, recognition memory impairment was fully reversed after a 4-week oral treatment in the diet (≈60 mg/kg/day). These cognitive effects were associated with a reversal of long-term potentiation (LTP) impairment in the hippocampus. A significant reduction in brain intraneuronal AβPP/Aβ levels and hyperphosphorylated tau, but no change in soluble or oligomeric Aβ levels was detected in Tg2576 mice showing functional recovery following CHF5074 treatment. We conclude that the beneficial effects of CHF5074 treatment in young transgenic mice occurred at a stage that precedes plaque formation and were associated with a reduction in intraneuronal AβPP/Aβ and hyperphosphorylated tau.  相似文献   
55.
A hallmark of immunoglobulin A nephropathy (IgAN) is episodes of gross hematuria coinciding with mucosal infections that can represent the disease-triggering event. Here we performed a whole genomic screen of IgAN patients during gross hematuria to clarify the link between mucosal antigens and glomerular hematuria. Modulated genes showed a clear involvement of the intracellular interferon signaling, antigen-presenting pathway, and the immunoproteasome. The mRNA and protein level of the chemokine receptor characterizing cytotoxic effector lymphocytes, CX3CR1, was upregulated. In vitro antigenic stimulation of peripheral blood mononuclear cells from IgAN patients, healthy blood donors, and other nephropathies with microscopic hematuria showed that only in IgAN patients was CX3CR1 enhanced in a dose-dependent manner. A significantly higher amount of glomerular and urinary fractalkine, the only ligand of CX3CR1, was also found in IgAN patients with recurrent episodes of gross hematuria compared with other patients with microscopic or no hematuria. This suggests a predisposition for cytotoxic cell extravasation only in patients with recurrent gross hematuria. Thus, we found a defect in antigen handling in peripheral blood mononuclear cells of IgAN patients with a specific increase of CX3CR1. This constitutive upregulation of glomerular and urinary fractalkine suggests an involvement of the CX3CR1-fractalkine axis in the exacerbation of gross hematuria.  相似文献   
56.
PURPOSE: The nephropathy associated with vesicoureteral reflux (VUR) is one of the leading causes of chronic renal failure (CRF) in children. We describe the clinical course of the disease based on information available in the ItalKid Project database, and analyze the predictive value of baseline renal function, age at VUR diagnosis and urinary protein excretion in relation to the risk of progressive renal failure. MATERIALS AND METHODS: As of December 31, 2001 the registry included a total of 343 patients (261 males) with a diagnosis of primary VUR, which was the leading single cause of CRF, accounting for 25.4% of all patients with CRF. RESULTS: The estimated risk of end stage renal disease (ESRD) by age 20 years was 56%. The patients with a creatinine clearance (Ccr) of less than 40 ml per minute at baseline had an estimated 4-fold greater risk of ESRD developing in comparison with those whose Ccr was 40 to 75 ml per minute. No significant difference in probability of disease progression to ESRD was found between subjects diagnosed with VUR at age 6 months or less and those diagnosed later (older than 6 months). Furthermore, children with normal urinary protein excretion (a urinary protein [uPr]/urinary creatinine [uCr] ratio of less than 0.2 in 36 patients) and low grade proteinuria (uPr/uCr 0.2 to 0.8 in 34 patients) at baseline showed a significantly slower decrease in mean Ccr than those with moderate proteinuria (uPr/uCr greater than 0.8 in 34 patients). Hypertension and/or antihypertensive treatment (including antiprogressive drugs) were reported in 29.1% of patients. CONCLUSIONS: The results of the present study define the long-term risk of ESRD in a large population of children with CRF and VUR, and provide some critical information for identifying the prognosis.  相似文献   
57.

Background

Some patients with typical (heartburn/regurgitation) symptoms of gastroesophageal reflux disease (GERD) are refractory to proton pump inhibitor (PPI) therapy. Impedance-pH monitoring can identify PPI-refractory patients who could benefit from laparoscopic fundoplication, but outcome data are scarce. We aimed to assess whether PPI-refractory GERD as diagnosed by impedance-pH monitoring can be cured by laparoscopic fundoplication.

Methods

Forty-four consecutive GERD patients with heartburn/regurgitation refractory to high-dose PPI therapy entered a 3-year outcome assessment following robot-assisted laparoscopic fundoplication. Preoperative on-PPI impedance-pH diagnostic criteria consisted of positive symptom association probability (SAP)/symptom index (SI), and/or abnormal percentage esophageal acid exposure time (%EAET), and/or abnormal number of total refluxes. GERD cure was defined by 3-year postoperative off-PPI normal impedance-pH findings with persistent symptom remission.

Results

Preoperatively, 24 of 38 (63 %) patients who completed the outcome assessment had a positive SAP/SI, 20 of 38 (53 %) for weakly acidic refluxes; 3 of 38 (8 %) patients had an abnormal %EAET, 11 of 38 (29 %) an abnormal number of total refluxes only. Postoperatively, heartburn/regurgitation recurred in 3 patients; abnormal impedance-pH findings were found in two of them, and they responded to PPI therapy. GERD cure was achieved in 34 of 38 (89 %) patients, 11 of 11 with an abnormal number of total refluxes as the only preoperative abnormal impedance-pH finding. Postoperatively, there was a significant decrease of the %EAET (1 vs. 0.1 %, P = 0.002) and of the number of total refluxes (68 vs. 8, P = 0.001), with the latter finding mainly due to a decrease in the number of weakly acidic refluxes.

Conclusions

Normal reflux parameters and persistent symptom remission at 3-year follow-up can be achieved with laparoscopic fundoplication in the majority of patients with PPI-refractory GERD as diagnosed by impedance-pH monitoring. On-PPI impedance-pH diagnostic criteria should include SAP/SI positivity, an abnormal %EAET, and an abnormal number of total refluxes. Weakly acidic refluxes have a major role in the pathogenesis of PPI-refractory GERD.  相似文献   
58.
Study Type – Diagnosis (RCT) Level of Evidence 1b What’s known on the subject? and What does the study add? Transrectal gray‐scale ultrasonography guided prostate biopsy sampling is the method for diagnosing prostate cancer (PC) in patients with an increased prostate specific antigen level and/or abnormal digital rectal examination. Several imaging strategies have been proposed to optimize the diagnostic value of biopsy sampling, although at the first biopsy nearly 10–30% of PC still remains undiagnosed. This study compares the PC detection rate when employing Colour Doppler ultransongraphy with or without the injection of SonoVueTM microbubble contrast agent, versus the transrectal ultrasongraphy‐guided systematic biopsy sampling. The limited accuracy, sensitivity, specificity and the additional cost of using the contrast agent do not justify its routine application in PC detection.

OBJECTIVE

? To compare prostate cancer (PC) detection rate employing colour Doppler ultrasonography with or without SonoVueTM contrast agent with transrectal ultrasonography‐guided systematic biopsy sampling.

PATIENTS AND METHODS

? A total of 300 patients with negative digital rectal examination and transrectal grey‐scale ultrasonography, with PSA values ranging between 2.5 and 9.9 ng/mL, were randomized into three groups: 100 patients (group A) underwent transrectal ultrasonography‐guided systematic bioptic sampling; 100 patients (group B) underwent colour Doppler ultrasonography, and 100 patients (group C) underwent colour Doppler ultrasonography before and during the injection of SonoVueTM. ? Contrast‐enhanced targeted biopsies were sampled into hypervascularized areas of peripheral, transitional, apical or anterior prostate zones. ? All the patients included in Groups B and C underwent a further 13 systematic prostate biopsies. The cancer detection rate was calculated for each group.

RESULTS

? In 88 (29.3%) patients a histological diagnosis of PC was made, whereas 22 (7.4%) patients were diagnosed with high‐grade prostatic intraepithelial neoplasia or atypical small acinar proliferation. ? No significant differences were found among the three groups for cancer detection rate (P= 0.329). ? Additionally, low sensitivity, specificity and accuracy of colour Doppler with or without SonoVueTM contrast agent were found.

CONCLUSIONS

? Prostate cancer detection rate does not significantly improve with the use of colour Doppler ultrasonography with or without SonoVueTM. ? Although no collateral effects have been highlighted, the combined use of colour Doppler ultrasonography and SonoVueTM determines adjunctive costs and increases the mean time for taking a single prostate biopsy.  相似文献   
59.
Alzheimer's disease (AD) is a major clinical concern, and the search for new molecules to combat disease progression remains important. One of the major hallmarks in AD pathogenesis is the hyperphosphorylation of tau and subsequent formation of neurofibrillary tangles. Several kinases are involved in this process. Amongst them, c-Jun N-terminal kinases (JNKs) are activated in AD brains and are also associated with the development of amyloid plaques. This study was designed to investigate the contribution of JNK in tau hyperphosphorylation and whether it may represent a potential therapeutic target for the fight against AD. The specific inhibition of JNK by the cell permeable peptide D-JNKI-1 led to a reduction of p-tau at S202/T205 and S422, two established target sites of JNK, in rat neuronal cultures and in human fibroblasts cultures. Similarly, D-JNKI-1 reduced p-tau at S202/T205 in an in vivo model of AD (TgCRND8 mice). Our findings support the fundamental role of JNK in the regulation of tau hyperphosphorylation and subsequently in AD pathogenesis.  相似文献   
60.

Background

The National Institutes of Health Stroke Scale (NIHSS) is able to predict mortality and functional outcome in patients with ischemic stroke. Its role in primary intracerebral hemorrhage (ICH) is not clear. The objective of our study was to investigate whether NIHSS is a reliable instrument of clinical monitoring and correlates with mortality and functional outcome in ICH.

Methods

One hundred fifty-six consecutive subjects with primary ICH were included. We evaluated NIHSS at admission. The functional state after a 30-day and a 3-month-long follow-up was assessed by the modified Rankin Scale (mRS). Spearman’s rank correlation coefficient analysis was used for statistics. Sensitivity, specificity, positive predictive value, negative predictive value, global accuracy, and ROC curve were computed using the median score 7 as NIHSS cutoff and the score 4 as mRS cutoff.

Results

Median NIHSS score at admission was 7 (16–4); the mean (± SD) was 10.82 (±?8.27). Thirty-two patients (20.5%) died within 30 days and other 22 (14.1%) within 3 months. The median mRS score at 3 months was 4 (6–1); the mean (± SD) was 3.38 (±?2.42). We found a statistically significant correlation between initial NIHSS score and mRS score after 30 days (0.74) and 3 months (0.66, p?<?0.01). Sensitivity was 93.5 and 92.2%, specificity 82.3 and 69.6%, and GA 87.8 and 80.8%, respectively, at 1 and 3 months. The 1- and 3-month ROC curves comparing initial NIHSS and mRS showed a fitted area as 0.914 and 0.833, respectively.

Conclusions

NIHSS is a reliable tool of clinical monitoring and correlates with 30-day and 3-month mortality and functional outcome in subjects with ICH.
  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