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   1128篇
  免费   67篇
  国内免费   10篇
儿科学   20篇
妇产科学   4篇
基础医学   100篇
口腔科学   2篇
临床医学   62篇
内科学   400篇
皮肤病学   21篇
神经病学   33篇
特种医学   27篇
外科学   251篇
预防医学   16篇
眼科学   55篇
药学   87篇
中国医学   6篇
肿瘤学   121篇
  2023年   18篇
  2022年   14篇
  2021年   34篇
  2020年   15篇
  2019年   22篇
  2018年   24篇
  2017年   26篇
  2016年   26篇
  2015年   32篇
  2014年   45篇
  2013年   50篇
  2012年   47篇
  2011年   47篇
  2010年   24篇
  2009年   23篇
  2008年   74篇
  2007年   77篇
  2006年   79篇
  2005年   64篇
  2004年   39篇
  2003年   57篇
  2002年   62篇
  2001年   36篇
  2000年   35篇
  1999年   41篇
  1998年   15篇
  1997年   15篇
  1996年   10篇
  1995年   7篇
  1994年   9篇
  1993年   8篇
  1992年   23篇
  1991年   15篇
  1990年   11篇
  1989年   11篇
  1988年   13篇
  1987年   6篇
  1986年   8篇
  1985年   7篇
  1984年   6篇
  1983年   6篇
  1982年   4篇
  1981年   2篇
  1979年   2篇
  1977年   2篇
  1976年   1篇
  1975年   6篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
排序方式: 共有1205条查询结果,搜索用时 15 毫秒
1.
Cholesterol monomer activity correlates with nucleation time in model bile   总被引:1,自引:0,他引:1  
Nucleation time (Cholesterol monohydrate crystallization) in bile has been introduced to distinguish patients with cholesterol gallstone from normal human beings. To test the hypothesis that cholesterol monomer activity correlates with nucleation time, we have examined the relationship between nucleation time, apparent cholesterol monomer activity and cholesterol monomer concentration in the aqueous phase using model biles containing bile salt, phospholipid and cholesterol. Apparent cholesterol monomer activity was inversely well correlated with nucleation time in the dilution study (r = -0.98) and in the cholesterol saturation study (r = -0.88) but positively with cholesterol monomer concentration in the aqueous phase in the dilution study (r = 0.72) and in the cholesterol saturation study (r = 0.93). The results indicate that cholesterol monomer activity reflects the nucleation time in model bile system.  相似文献   
2.
We previously reported the expression profiles of 9 cytochrome P450 isozymes (CYPs) proteins and those of 40 CYPs genes in pregnant rat's liver, placenta and fetal liver after treatment with pregnenolone-16alpha-carbonitrile (PCN) or phenobarbital (PB). This study was carried out focusing on the gene expression profiles of Phase II drug metabolizing enzymes, Glutathione S-transferase isozymes (GSTs) and UDP-glycosyltransferase isozymes (UDPGTs). Fischer 344 (F344) pregnant rats were daily treated intraperitoneally with 50 mg/kg of PCN or 80 mg/kg of PB from 13 to 16 days of gestation (DG). They were sacrificed on 17 DG, and microarray analysis using Affymetrix Rat Expression Array 230 A was performed. Among 16 GSTs genes examined in this study, 7 genes were significantly induced in dam's liver and 3 genes in fetal liver, respectively, in the PCN-group, while 8 genes were significantly induced in dam's liver and 1 gene in fetal liver, respectively, in the PB-group. On the other hand, among 11 UDPGTs genes examined, 5 genes were significantly induced in dam's liver and 3 genes in fetal liver, respectively, in the PCN-group, while 5 genes were significantly induced in dam's liver and 1 gene in fetal liver, respectively, in the PB-group. There were no significant changes in the placenta of all groups. This is the first report of the gene expression profiles of Phase II drug metabolizing enzymes in pregnant rat and fetal livers and placenta after treatment with typical inducers of drug metabolizing enzymes.  相似文献   
3.
4.
In a retrospective study, antibody to hepatitis C virus (anti-HCV antibody) was measured in 80 patients with acute viral hepatitis (type A, 18; type B, 21; type non-A,non-B, 41). Anti-HCV antibody was found in 12 of 20 patients (60%) with non-A,non-B post-transfusion hepatitis (NANB-PTH) and in 9 of 21 patients (43%) with sporadic NANB hepatitis (NANB-SPO). Patients with acute hepatitis type A or type B did not have anti-HCV antibody. The number of patients who developed chronic hepatitis was greater in the group with anti-HCV antibody than in the anti-HCV negative group in both NANB-PTH and NANB-SPO. The difference was significant in those with NANB-PTH (P less than 0.05). To investigate the relationship between the long-term prognosis of NANB-PTH and the course of anti-HCV, we studied anti-HCV antibody in 12 patients who developed chronic type C hepatitis (C-CH) after PTH and followed them for more than 5 years after the development of PTH. One year after the development of PTH, all 12 had anti-HCV antibody. Five lost anti-HCV antibody (group 1) while 7 remained positive (group 2) at the final examination. Four of the 5 patients in group 1 had normal serum transaminases; however, abnormal transaminase persisted in all 7 patients in group 2 until the end of follow-up (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
5.
The prevalence of hepatitis C antibodies (anti- HCV) among multitransfused patients was studied and compared with predicted values obtained from a post-transfusion hepatitis study and from data on the prevalence of anti-HCV among blood donors. The prevalence of hepatitis B core antibodies (anti-HBc) was also studied to determine the routes of transmission of hepatitis C virus. The patients consisted of 65 dialysis patients (57 on haemodialysis and 8 on continuous ambulatory peritoneal dialysis) and 71 leukemia patients in long-term remission [49 with acute myeloid leukemia (AML) and 22 with acute lymphatic leukemia (ALL)]. The presence of anti-HCV was investigated using a second generation enzyme-linked immunosorbent assay. Reactive samples were confirmed by a second generation recombinant immunoblot assay. Anti-HBc was studied in the 65 dialysis patients and in 40 of the leukemia patients. Three (4.6%) of the 65 dialysis patients and 12 (24.5%) of the 49 AML patients were anti-HCV positive whereas all of the ALL patients were seronegative. The total number of blood units transfused to 134 patients (data on two dialysis patients were not available) was 18,148, out of which 17,575 units had been transfused prior to the initiation of anti- HCV screening of blood donors. On the basis of the anti-HCV prevalence among blood donors and the incidence of post-transfusion hepatitis, the predicted number of seropositive patients was 11 and 18, respectively. Five of the 65 dialysis patients were anti-HBc positive, compared with only one of the 40 leukemia patients. It is concluded that the anti-HCV prevalence among dialysis and leukemia patients is concordant with the risk of receiving contaminated blood products, whereas hepatitis B infection may have other routes of transmission in dialysis patients. © 1993 Wiley-Liss, Inc.  相似文献   
6.
One hundred and forty four patients with chronic hepatitis B were tested to identify new mutations associated with hepatitis B e antigen (HBeAg) negativity, using a full genome sequence analysis. All the patients were Chinese and had hepatitis B virus infection of genotype C. Patients with none of the pre-core or core promoter mutations were significantly (P < 0.001) less common in the group with anti-HBe (13%) than in the group with HBeAg (56%). The complete nucleotide sequence was determined in four anti-HBe-positive patients who had neither pre-core nor core promoter mutations and in five HBeAg-positive patients who also had neither of these mutations (the groups were matched for age and sex). Six mutations were found to be significantly more common in the former group than in the latter: G529A (3/4 vs. 0/5), C934A (4/4 vs. 1/5), A1053G (4/4 vs. 1/5), G1915T/A (4/4 vs. 0/5), T2005C/A (4/4 vs. 0/5), and C3026T (3/4 vs. 0/5). Three of the six mutations were significantly more common in the four anti-HBe-positive patients who had neither pre-core nor core promoter mutations, compared to 11 HBeAg-positive patients who had pre-core and core promoter mutations, and also compared to 15 anti-HBe-positive patients who had pre-core and core promoter mutations, suggesting further the specificity of these mutations. Of the six mutations, two resulted in amino acid substitution in the polymerase protein, and one is located near the enhancer I region. The results suggest that the six newly discovered mutations are associated with HBeAg negativity.  相似文献   
7.
Adult Still's disease reflects a Th2 rather than a Th1 cytokine profile   总被引:2,自引:0,他引:2  
Adult Still's disease (ASD) is a chronic multisystemic disease. Extraordinarily high serum levels of IL-18 in ASD patients have been described, whereas the mechanism remains to be clarified. This study aimed to evaluate proinflammatory cytokines and to consider their pathological roles. In patients with rheumatic diseases (n = 151), blood samples were taken at the active phase and the serum levels of IL-18 and other proinflammatory cytokines were measured by ELISA. The extra-high levels of IL-18 were confirmed selectively in ASD patients (n = 10). In the active phase of ASD patients, the levels of IL-6 were elevated accordingly, but IL-1beta and TNF-alpha were undetectable. As to Th1-Th2 cytokines, the levels of IL-4 and IL-13, but not INF-gamma, IL-12, or IL-2, were elevated in all ASD patients examined. Moreover, the serum levels of IL-18 showed a good correlation with those of IL-4, suggesting that ASD reflects a Th2 rather than a Th1 cytokine profile.  相似文献   
8.
The localization of hepatitis C virus (HCV) in the liver has not been well clarified. We report successful indirect immunoperoxidase staining of the HCV core antigen using polyclonal antibodies raised in rabbits and conventional formalin-fixed, paraffin-embedded needle biopsy sections of liver. The core antigen was distributed in a fine granular pattern diffusely, perisinusoidally, or focally within the hepatocellular cytoplasm of livers from patients with HCV infection. The staining tended to show a more heterogeneous pattern in terms of intensity and distribution in cases of more advanced disease. Hepatocellular carcinoma cells were also frequently stained. HCV immunostaining will provide important information on the pathogenesis and treatment of HCV-related liver diseases.  相似文献   
9.
Many T cells infiltrate into the liver of patients with chronic hepatitis C (CH-C). They are believed to play a crucial role in the immunopathogenesis of hepatic inflammation, but their clonality and specificity are unknown. The aim of this study was to clarify the characteristics of these T cells. We analysed the complementarity-determining region (CDR)3 size lengths of T cell receptor (TCR) beta-chains by size spectratyping, and determined the sequences of Vbeta CDR3 after subcloning Vbeta-specific polymerase chain reaction products. Spectratyping showed clonal expansions in all liver specimens, most of which showed more than two T cell clones. Moreover, many non-clonal T cells also accumulated in the liver. Clonality of the T cells suspected by spectratyping was confirmed by CDR3 sequencing. Although the sequences revealed no whole CDR3-shared clones among different patients, some common motif sequences were observed. Our data suggest that T cells are stimulated by several hepatitis C virus (HCV) epitopes, then accumulate in the liver of CH-C patients. Shared motifs of expanded T cell clones suggest that they might recognize the same regions of HCV peptides, but have differences due to HCV peptide mutational changes. These clones might also interact with non-clonal T cells and play a crucial role in the immunopathogenesis of CH-C.  相似文献   
10.
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