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   980篇
  免费   71篇
  国内免费   3篇
耳鼻咽喉   6篇
儿科学   47篇
妇产科学   43篇
基础医学   185篇
口腔科学   50篇
临床医学   75篇
内科学   205篇
皮肤病学   8篇
神经病学   163篇
特种医学   27篇
外科学   50篇
综合类   3篇
预防医学   81篇
眼科学   46篇
药学   45篇
肿瘤学   20篇
  2023年   8篇
  2022年   10篇
  2021年   27篇
  2020年   14篇
  2019年   23篇
  2018年   26篇
  2017年   24篇
  2016年   20篇
  2015年   24篇
  2014年   21篇
  2013年   47篇
  2012年   68篇
  2011年   59篇
  2010年   33篇
  2009年   39篇
  2008年   57篇
  2007年   52篇
  2006年   46篇
  2005年   46篇
  2004年   40篇
  2003年   46篇
  2002年   47篇
  2001年   20篇
  2000年   17篇
  1999年   31篇
  1998年   17篇
  1997年   12篇
  1996年   11篇
  1995年   11篇
  1994年   7篇
  1993年   9篇
  1992年   15篇
  1991年   7篇
  1990年   14篇
  1989年   14篇
  1988年   8篇
  1987年   8篇
  1986年   9篇
  1985年   6篇
  1984年   6篇
  1983年   9篇
  1982年   3篇
  1981年   6篇
  1980年   4篇
  1979年   4篇
  1976年   5篇
  1975年   3篇
  1974年   6篇
  1973年   4篇
  1972年   3篇
排序方式: 共有1054条查询结果,搜索用时 328 毫秒
961.
OBJECTIVE: The primary purpose of this study was to confirm the association of a specific haplotype of the dopamine transporter gene and attention deficit hyperactivity disorder (ADHD), which could be one source of the heterogeneity seen across published studies. METHOD: The authors previously reported the association of ADHD with a subgroup of chromosomes containing specific alleles of two variable-number tandem repeat polymorphisms within the 3' untranslated region and intron 8 of the dopamine transporter gene. They now report on this association in a sample of ADHD combined-type probands. RESULTS: The original observations were confirmed, with an overall odds ratio of 1.4 across samples. CONCLUSIONS: These data challenge results of meta-analyses suggesting that dopamine transporter variation does not have an effect on the risk for ADHD, and they indicate that further investigation of functional variation in the gene is required.  相似文献   
962.
963.
Autosomal recessive LPIN1mutations have been recently described as a novel cause of rhabdomyolysis in a few families. The purpose of the study was to evaluate the prevalence of LPIN1mutations in patients exhibiting severe episodes of rhabdomyolysis in infancy. After exclusion of primary fatty acid oxidation disorders, LPIN1 coding sequence was determined in genomic DNA and cDNA. Among the 29 patients studied, 17 (59%) carried recessive nonsense or frameshift mutations, or a large scale intragenic deletion. In these 17 patients, episodes of rhabdomyolysis occurred at a mean age of 21 months. Secondary defect of mitochondrial fatty oxidation or respiratory chain was found in skeletal muscle of two patients. The intragenic deletion, c.2295‐866_2410‐30del, was identified in 8/17 patients (47%), all Caucasians, and occurred on the background of a common haplotype, suggesting a founder effect. This deleted human LPIN1 form was unable to complement Δpah1 yeast for growth on glycerol, in contrast to normal LPIN1. Since more than 50% of our series harboured LPIN1mutations, LPIN1 should be regarded as a major cause of severe myoglobinuria in early childhood. The high frequency of the intragenic LPIN1deletion should provide a valuable criterion for fast diagnosis, prior to muscle biopsy. © 2010 Wiley‐Liss, Inc.  相似文献   
964.
Nonalcoholic fatty liver disease (NAFLD) is linked to the metabolic syndrome. The aim of the present study is to determine the effect of the metabolic syndrome on left ventricular (LV) geometry and function using as a model patients with NAFLD. Thirty-eight patients with NAFLD, less than 55 years of age and with a normal exercise test, were compared with an age and sex-matched control group. Patients with diabetes mellitus, hypertension, and body mass index>40 were excluded. A complete echocardiographic study including tissue Doppler imaging (TDI) was performed. The following parameters were assessed by echo Doppler: peak velocities of early (E) and late (A) diastolic filling, E/A ratio, flow propagation velocity (Vp). Using TDI early diastolic velocity (E'), and systolic velocity (S') of mitral annulus were obtained. The patients with NAFLD had a significantly higher body mass index (31.4+/-5 vs. 26.4+/-4 kg/m, P=0.01), higher glucose (100.6+/-13 vs. 83.0+/-10 mg/dL, P=0.01), and triglyceride levels (126.5+/-44 vs. 206.5+/-67 mg/dL, P<0.001). Increased thickness of the intraventricular septum, posterior wall (11.03+/-2.2 vs. 8.9+/-2.9 mm, P=0.001; 8.5+/-1.7 vs. 9.7+/-2.3 mm, P=0.04), and larger LV mass and LV mass/height (160.7+/-58.7 vs.115.3+/-35.4 g, P=0.001 and 92.6+/-29.5 vs. 69.2+/-19.8 g/m, P=0.001, respectively) were found in NAFLD group. LV systolic function was similar in both groups. Patients with NAFLD had a lower E (73.6+/-11.0 vs. 86.4+/-20.0 cm/s, P<0.006) and E/A ratio (1.0+/-0.3 vs. 1.76+/-0.8 P<0.0001). Moreover, the Vp and the E' on TDI were significantly lower compared with the control group (49.0+/-9.7 vs. 74.7+/-18.4 cm/s, P<0.0001 and 10.3+/-2.0 vs. 13.8+/-1.7 cm/s, P<0.0001, respectively). On multivariate analysis the E' on TDI was the only independent parameter associated with NAFLD. In conclusion, patients with NAFLD in the absence of morbid obesity, hypertension, and diabetes have mildly altered LV geometry and early features of left ventricular diastolic dysfunction. Early diastolic velocity on TDI was found to be the only index that could identify the patients with NAFLD and metabolic syndrome.  相似文献   
965.
Objective: To compare perinatal outcome of women after third trimester oral glucose tolerance test (GTT) following normal glucose challenge test (GCT) stratified by test results.

Study design: Retrospective cohort study of women delivered in a tertiary, university affiliated medical center (2007–2012). Inclusion criteria were women with a normal 50?g GCT (<140?mg/dl) followed by GTT, who delivered a live-born fetus >28 gestational weeks. Gestational diabetes mellitus (GDM) was defined as ≥2 pathological values on GTT (Carpenter and Coustan’s criteria). Perinatal outcome was stratified by GTT results: normal (if all 4 values were normal), single pathological value or GDM. Logistic regression analysis was utilized to adjust outcomes to potential confounders.

Results: Overall, 323 women met inclusion criteria. Of them, 277 (85.8%) had 4 normal values, 32 (9.9%) had a single pathological value and 14 (4.3%) had late-onset GDM. Infants of mothers diagnosed and treated as GDM had lower birth weights, compared to non-diabetics and those with a single pathological value GTT. Mothers with GTT ≥1 pathological values had statistically insignificant higher rates of cesarean delivery. However, this difference was not significant after adjustment to potential confounders.

Conclusion: Treatment of late-onset GDM may lead to lower birthweights, presumably due to glucose control. No association was found with cesarean delivery or neonatal outcome.  相似文献   
966.
AIM: To assess the safety and efficacy of trans-arterial chemo-embolization (TACE) in very elderly patients. METHODS: A prospective cohort study, from 2001 to 2010, compared clinical outcomes following TACE between patients ≥ 75 years old and younger patients (aged between 65 and 75 years and younger than 65 years) with hepatocellular carcinoma (HCC), diagnosed according to the European Association for the Study of the Liver and the American Association for the Study of Liver Diseases criteria. The decision that patients were not candidates for curative therapy was made by a multidisciplinary HCC team. Data collected included demographics, co-morbidities, liver disease etiology, liver disease severity and the number of procedures. The primary outcome was mortality; secondary outcomes included post-embolization syndrome (nausea, fever, abdominal right upper quadrant pain, increase in liver enzymes with no evidence of sepsis and with a clinical course limited to 3-4 d post procedure) and 30-d complications. Additionally, changes in liver enzyme measurements were assessed [alanine and aspartate aminotransferase (ALT and AST), gamma-glutamyl transpeptidase and alkaline phosphatase] in the week following TACE. Analysis employed both univariate and multivariate methods (Cox regression models). RESULTS: Of 102 patients who underwent TACE as sole treatment, 10 patients (9.8%) were > 80 years old at diagnosis; 13 (12.7%) were between 75 and 80 years, 45 (44.1%) were between 65 and 75 years and 34 (33.3%) were younger than 65 years. Survival analysis demonstrated similar survival patterns between the elderly patients and younger patients. Age was also not associated with the adverse event rate. Survival rates at 1, 2 and 3 years from diagnosis were 74%, 37% and 31% among patients < 65 years; 83%, 66% and 48% among patients aged 65 to 75 years; and 86%, 41% and 23% among patients ≥ 75 years. There were no differences between the age groups in the pre-procedural care, including preventive treatment for contrast ne  相似文献   
967.
968.
We report the isolation of a novel Tumor-Cells Apoptosis Factor (Nerofe). We found that cDNA of this protein is expressed mainly in the human thymus and partially in the colon and in the frontal lobe of brain. Immunohistochemical studies localize Tumor-Cells Apoptosis Factor (TCApF) to the medulla and Hassal's corpuscles of the thymus gland, which are responsible for negative selection. Treatment of mice with induced AML terminates the cancer development and completely eliminates metastatic cell colonies from the bone marrow and the spleen that reduces probability of the cancer return. We find that TCApF binds to the T1/ST2 receptor and activates caspases 8, 9 and 3 mediated apoptosis, together with activation of JNKinase and p38 MAPKinase. Application of TCApF to cells induced apoptosis in acute myeloid leukemia proliferating cells (U937 premeyloid cells), in human breast carcinoma (MCF7), human glioblastoma, human neuroblastoma, human prostate cancer and human lung cancer proliferating cells. In contrast, TCApF was unable to induce apoptosis in non-proliferating cells. The selectivity of TCApF-induced apoptosis is related to the level of T1/ST2 receptor expression. This is the first report linking the T1/ST2 receptor to apoptosis.  相似文献   
969.
Many studies have suggested that the intraparietal sulcus (IPS), particularly in the dominant hemisphere, is crucially involved in numerical comparisons. However, this parietal structure has been found to be involved in other tasks that require spatial processing or visuospatial attention as well. fMRI was used to investigate three different magnitude comparisons in an event-related-block design: (a) Which digit is larger in numerical value (e.g., 2 or 5)? (b) Which digit is brighter (e.g., 3 or 3)? (c) Which digit is physically larger (e.g., 3 or 3)? Results indicate a widespread cortical network including a bilateral activation of the intraparietal sulci for all different comparisons. However, by computing contrasts of brain activation between the respective comparison conditions and applying a cortical distance effect as an additional criterion, number-specific activation was revealed in left IPS and right temporal regions. These results indicate that there are both commonalities and differences in the spatial layout of the brain systems for numerical and physical comparisons and that especially the left IPS, while involved in magnitude comparison in general, plays a special role in number comparison.  相似文献   
970.
Nine hundred sixty consecutive cardiac catheterization procedures were studied prospectively for the presence of periprocedural bacteremia. Overall, among 960 procedures, only 4 were associated with clinically significant bacteremia. All 4 were related to the intravenous line and none to the cardiac procedure itself. Clinically nonsignificant bacteremias were correlated with procedural duration, multiple skin punctures, use of multiple balloons, and obesity.  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