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   2565篇
  免费   78篇
  国内免费   80篇
耳鼻咽喉   2篇
儿科学   94篇
妇产科学   16篇
基础医学   166篇
口腔科学   41篇
临床医学   295篇
内科学   937篇
皮肤病学   4篇
神经病学   74篇
特种医学   44篇
外科学   83篇
综合类   211篇
预防医学   142篇
眼科学   9篇
药学   458篇
  2篇
中国医学   112篇
肿瘤学   33篇
  2023年   78篇
  2022年   107篇
  2021年   117篇
  2020年   116篇
  2019年   121篇
  2018年   102篇
  2017年   69篇
  2016年   74篇
  2015年   67篇
  2014年   236篇
  2013年   178篇
  2012年   158篇
  2011年   175篇
  2010年   131篇
  2009年   128篇
  2008年   111篇
  2007年   117篇
  2006年   76篇
  2005年   83篇
  2004年   48篇
  2003年   28篇
  2002年   40篇
  2001年   28篇
  2000年   27篇
  1999年   33篇
  1998年   21篇
  1997年   20篇
  1996年   11篇
  1995年   19篇
  1994年   27篇
  1993年   8篇
  1992年   18篇
  1991年   15篇
  1990年   8篇
  1989年   4篇
  1988年   10篇
  1987年   6篇
  1986年   11篇
  1985年   10篇
  1984年   11篇
  1983年   9篇
  1982年   10篇
  1981年   12篇
  1980年   8篇
  1979年   7篇
  1978年   5篇
  1977年   8篇
  1976年   7篇
  1975年   4篇
  1973年   4篇
排序方式: 共有2723条查询结果,搜索用时 46 毫秒
51.
Abstract: To determine whether pretreatment HCV-RNA level, hepatitis C virus genotypes, alanine aminotransferase and histology correlate with subsequent response to interferon-α therapy or not, serum HCV-RNA levels and genotype were determined by branched DNA signal amplification assay and genotype-specific polymerase chain reaction in 43 patients with chronic active hepatitis C. Response to recombinant interferon-α 2α (504 million units in total) was defined as complete and sustained CR→SR, n=12), complete response followed by relapse (CR→Rel, n=17), and no response (NR, n=10), excluding dropouts (n=4). Patients who showed CR→SR had a lower HCV-RNA level (0.438 × 106 eq/ml) compared to CR→Rel (2.452 × 106 eq/ml, p=0.008) and NR (4.882 × 106 eq/ml, p=0.009). A higher proportion of patients with CR→SR had type 2a HCV (67%) compared to the CR→Rel (28%) and the NR (0%). There was a trend for type 1b hepatitis C virus infection to have higher serum HCV-RNA levels. There was no correlation between pretreatment HCV-RNA level and alanine aminotransferase. However, no relation between pretreatment HCV-RNA level and liver histology was observed; a high proportion of patients with CAH2a showed CR→SR, compared to those with CAH2b (p=0.001). Moreover, the patients with CAH2b who had low level hepatitis C virus viremia did not show CR→SR. These data indicate that pre-treatment serum HCV-RNA levels, genotype and liver histology are good predictors of subsequent response to interferon-α therapy in Japanese patients with chronic hepatitis C virus infection.  相似文献   
52.
BackgroundControversy persists about the role of hepatitis C as a risk factor for developing kidney disease in the general population. Some authors have evaluated the effect of antiviral therapy for HCV on the risk of kidney disease.Study Aims and DesignA systematic review of the published medical literature was performed to assess whether antiviral therapy for HCV has an independent impact on kidney survival in the adult general population. A random effects model was used to generate an overall estimate of the risk of kidney disease after anti-HCV therapy across the published studies. Meta-regression and stratified analysis were also carried out.ResultsFifteen studies were eligible (n = 356, 285 patients) and separate meta-analyses were conducted according to the outcome. Pooling studies based on viral responses (n = 7; 34,763 individual patients) demonstrated a relationship between sustained viral response and lower frequency of kidney disease; the overall estimate for adjusted risk of kidney disease was 2.50 (95% CI, 1.41; 4.41) (p = 0.0016) and between-study heterogeneity was found (p-value by Q test = 0.004). Aggregation of studies comparing treated vs untreated cohorts (n = 8, n = 333,312 patients) revealed an association between anti-HCV therapy and lower risk of kidney disease. The overall estimate for adjusted risk of kidney disease across the eight studies was 0.39 (95% CI, 0.25; 0.612) (p = 0.0001). Meta-regression showed that the effectiveness of antiviral therapy in reducing the frequency of kidney disease diminishes as cirrhosis (p = 0.02) and HBV infection (p = 0.0001) increase among HCV-infected individuals.ConclusionsAntiviral therapy for HCV lowers the risk of kidney disease among HCV-infected individuals. Studies to understand the mechanisms underlying this association are ongoing.  相似文献   
53.
Alanine is a nutritionally nonessential amino acid synthesized by transamination of pyruvate originated from glucose. Alanine is the principal gluconeogenic amino acid because it can originate pyruvate and glucose through the inverse pathway. Considering that it has been suggested that alanine could be used as a dietary supplement in combination with growth hormone in the treatment of undernourished children affected by some inherited metabolic diseases to induce anabolism, the principal objective of the present work was to measure the activities of the mitochondrial respiratory chain complexes and succinate dehydrogenase in brain cortex of Wistar rats subjected to chronic alanine administration from the 6th to the 21st day of life. We also investigated the in vitro effect of alanine on the activities of mitochondrial respiratory chain complexes and succinate dehydrogenase in the same brain structure of 22-day-old rats. The results showed a reduction of Complex I + III and succinate dehydrogenase activities in brain cortex of rats subjected to alanine administration. We also verified that alanine inhibited the in vitro activity of Complexes I + III by competition with NADH. These results indicate that more investigation would be necessary before considering alanine supplementation as a valid adjuvant therapy to sick children with these disorders.  相似文献   
54.
55.
56.
AIM: To investigate the association between cytokine gene polymorphism and disease status in chronic hepatitis C genotype 3 by liver biopsy, ALT, HCV RNA levels and response to treatment. METHODS: Patients with chronic hepatitis C genotype 3 were analyzed for single nucleotide polymorphisms of interleukin (IL)-10, IL-1 beta, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) by polymerase chain reaction using sequence-specific oligonucleotide primers. Liver biopsies were assessed by modified histological activity index (HAI) scoring system using a scale of 0-18 for grading the necro-inflammatory activity and 0-6 for staging the fibrosis. HCV RNA levels were determined by bDNA assay. The patients were treated with interferon alpha and ribavirin for 6 mo. Sustained virological response was assessed 6 mo after the completion of the treatment. RESULTS: Out of the 40 patients analyzed, 26 were males. Mean age was 40.5±12.5 years (range 18-65 years). The frequencies of different dimorphic polymorphisms based on single nucleotide substitution were as follows: IL-10-1082 G/A 85%, A/A 12.5%, G/ G 2.5%; IL-10-819 A/C 87.5%, C/C 10%, A/A 2.5%; IL-10-592 C/A 72.5%, C/C 27.5%; IL-1 C 90%, U 10%; IFN-874 T/A 50%, T/T 27.5%, A/A 22.5%; TNF-308 A/G 95%, GIG 5%; TGF-10 T/C 52.5%, C/C 35%, T/T 12.5%. The mean grades of necro-inflammatory activity of different genotypes of IL-10 at promoter site -1082 were A/A = 3.6, A/G = 5.0, and G/G = 10.0 and the difference was significant (P = 0.029). The difference in the stage of disease at a scale of 0-6 was A/A 0.8, A/G 2.3, and G/G 4.0 (P = 0.079). The difference in the HAI seemed to be related to the presence of allele -1082G. For IL-10 -819 genotypes, mean scores of fibrosis were A/A = 6.0, A/C = 2.2, and C/C = 1.0 (P = 0.020) though the inflammatory activity was not much different. No significant differences in HAI were noted among polymorphisms of other cytokines. Moreover, ALT and HCV RNA levels were not significantly different among different cvtokine polymorphisms. There was a significant correlation of HAI and HCV RNA levels with the duration of disease. TGFBBB -10 genotype CC patients had a better end of treatment response than those with other genotypes (P = 0.020). Sustained virological response to the treatment was not influenced by the cytokine polymorphism. No effect of other factors like viral load, degree of fibrosis, gender, steatosis, was observed on sustained virological response in this population infected with genotype 3. CONCLUSION: There is no significant correlation between cytokine polymorphisms and HAI except for the polymorphisms of anti-inflammatory cytokine IL-10, which may influence hepatic inflammatory activity and fibrosis in patients with chronic hepatitis C genotype 3. Sustained virological response in this genotype does not seem to be influenced by cytokine gene polymorphisms.  相似文献   
57.
58.
59.
Quantitating hepatic steatosis is important in many liver diseases and liver transplantation. Since steatosis estimation by pathologists has inherent intra- and inter-observer variability, we compared and contrasted computerized techniques with magnetic resonance imaging measurements, pathologist visual scoring, and clinical parameters. Computerized methods applied to whole slide images included a commercial positive pixel count algorithm and a custom algorithm programmed at our institution. For all liver samples (n = 59), including pediatric, adult, frozen section, and permanent specimens, statistically significant correlations were observed between pathology, radiology, and each image analysis modality (r = 0.75–0.97, p < 0.0001), with the strongest correlations in the pediatric cohort. Statistically significant relationships were observed between each method and with body mass index (r = 0.37–0.56, p from <0.0001 to <0.05) and with albumin (r = 0.55–0.64, p < 0.05) but not with alanine aminotransferase or aspartate aminotransferase. Although pathologist assessments correlated (r = 0.64–0.86, 0.92–0.97, and 0.78–0.91 for microvesicular, macrovesicular, and overall steatosis, respectively), the absolute values of hepatic steatosis visual assessment were susceptible to intra- and inter-observer variability, particularly for microvesicular steatosis. Image analysis, pathologist assessments, radiology measurements, and several clinical parameters all showed correlations in this study, providing evidence for the utility of each method in different clinical and research settings.  相似文献   
60.
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