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   3589篇
  免费   181篇
  国内免费   7篇
耳鼻咽喉   31篇
儿科学   98篇
妇产科学   18篇
基础医学   501篇
口腔科学   63篇
临床医学   179篇
内科学   762篇
皮肤病学   126篇
神经病学   478篇
特种医学   98篇
外科学   570篇
综合类   16篇
预防医学   81篇
眼科学   178篇
药学   306篇
中国医学   7篇
肿瘤学   265篇
  2023年   17篇
  2022年   24篇
  2021年   54篇
  2020年   22篇
  2019年   31篇
  2018年   74篇
  2017年   35篇
  2016年   44篇
  2015年   60篇
  2014年   71篇
  2013年   99篇
  2012年   156篇
  2011年   159篇
  2010年   99篇
  2009年   76篇
  2008年   141篇
  2007年   142篇
  2006年   158篇
  2005年   142篇
  2004年   179篇
  2003年   171篇
  2002年   158篇
  2001年   137篇
  2000年   126篇
  1999年   121篇
  1998年   42篇
  1997年   38篇
  1996年   30篇
  1995年   37篇
  1994年   37篇
  1993年   40篇
  1992年   109篇
  1991年   96篇
  1990年   93篇
  1989年   80篇
  1988年   63篇
  1987年   83篇
  1986年   79篇
  1985年   60篇
  1984年   45篇
  1983年   38篇
  1982年   28篇
  1981年   16篇
  1980年   17篇
  1979年   26篇
  1977年   15篇
  1975年   21篇
  1972年   20篇
  1969年   16篇
  1967年   20篇
排序方式: 共有3777条查询结果,搜索用时 15 毫秒
101.
Cytomegalovirus-specific cytotoxic T-lymphocytes (CMV-CTL) are essential for the control of CMV reactivation. To monitor the quantity and function of CMV-CTL after hematopoietic stem cell transplantation (HSCT), two CMV epitopes that bind to HLA-A*0201 NLVPMVATV (A*02NLV) and HLA-A*2402 QYDPVAALF (A*24QYD) were evaluated for their immunological potential. Samples from patients with the HLA-A*02 or HLA-A*24 serotype were analyzed by tetramer, intracellular cytokine staining and enzyme-linked immunospot (ELISPOT) assay. There were significantly more A*02NLV-specific CMV-CTL than A*24QYD (23 x 10(6) vs 0.4 x 10(6)/l). The frequency of IFN-gamma-producing cells was also higher upon stimulation with A*02NLV than with A*24QYD (2.5 vs 0.1%/CD8). Furthermore, the magnitude of CMV-CTL expansion was two- to 50-fold when cells were cultured with A*02NLV, while only an insignificant increase was observed in culture with A*24QYD. Although the number of A*24QYD-specific CMV-CTL was very low in most of the HLA-A*24 patients, the incidence of CMV reactivation did not differ between those with HLA-A*02 and HLA-A*24 serotype alone. These results suggest that an epitope other than A*24QYD plays a major role in patients with HLA-A*24. Our study also showed that A*02NLV may be a useful epitope for monitoring CMV-CTL not only in patients with HLA-A*0201 but also in those with the A*0206 genotype.  相似文献   
102.
103.
“Soft pancreas” has often been reported as a predictive factor for postoperative pancreatic fistula (POPF) after pancreatectomy. However, pancreatic stiffness is judged subjectively by surgeons, without objective criteria. In the present study, pancreatic stiffness was quantified using intraoperative ultrasound elastography, and its relevance to POPF and histopathology was investigated. Forty-one patients (pancreatoduodenectomy, 30; distal pancreatectomy, 11) who underwent intraoperative elastography during pancreatectomy were included. The elastic ratio was determined at the pancreatic resection site (just above the portal vein) and at the remnant pancreas (head or tail). Correlations between the incidence of POPF and patient characteristics, operative variables, and the elastic ratio were examined. In addition, the relationship between the elastic ratio and the percentage of the exocrine gland at the resection stump was investigated. For pancreatoduodenectomy patients, main pancreatic duct diameter < 3.2 mm and elastic ratio < 2.09 were significant risk factors for POPF. In addition, the elastic ratio, but not main pancreatic duct diameter, was significantly associated with the percentage of exocrine gland area at the pancreatic resection stump. Pancreatic stiffness can be quantified using intraoperative elastography. Elastography can be used to diagnose “soft pancreas” and may thus be useful in predicting the occurrence of POPF.Key words: Elastography, Exocrine gland, Pancreatectomy, Pancreatic stiffness, Postoperative pancreatic fistulaDespite current advances in surgical techniques, pancreatectomy is a very difficult procedure associated with the risk of multiple postoperative complications. The morbidity and mortality are reported to be 20–50% and 1–5%, respectively.1 In particular, a postoperative pancreatic fistula (POPF) can sometimes lead to life-threatening complications, such as hemoperitoneum and sepsis. The worldwide incidence of POPF is reported to be 5–50%. Several predictive factors for POPF have been reported to date, and, of these, “soft pancreas” has often been mentioned.24 However, in all of these reports, evaluation of pancreatic stiffness has depended on subjective judgment by the surgeon, without objective parameters as criteria.Elastography has recently been developed to enable real-time visualization of the relative stiffness of tissue elasticity, and its usefulness in various clinical disciplines for tumor diagnosis and differential diagnosis has been described.5 In gastroenterology, evaluation of liver fibrosis and diagnosis of pancreatic tumors and chronic pancreatitis using endoscopic ultrasound (EUS) have been reported,6,7 but the use of elastography in surgery has not been reported. An objective assessment of pancreatic stiffness as a predictive risk factor for POPF can help in choosing the intraoperative surgical technique and in planning the postoperative management strategy. Therefore, in the present study, pancreatic stiffness was quantified using intraoperative ultrasound elastography, and its relevance to POPF and histopathology was investigated.  相似文献   
104.
105.
106.
A 13 year-old girl with Down's syndrome was admitted to our hospital with a very positive reaction to PPD 5TU, abnormal shadow on the chest X-ray films and diarrhea. She suffered from acute enterocolitis one year ago, and then has been complaining of abdominal pain, appetite loss, and weight loss for a year. After admission, she was diagnosed as tuberculous pleuritis and suspected intestinal tuberculosis by laboratory examination. She recovered without sequelae by the combination therapy of SM, INH, and RFP, and was discharged after 5 months. The diagnosis of intestinal tuberculosis was confirmed by Colon Fiberscopy showing ulceration at the ileocecal region and simultaneous biopsy showing granuloma. Surgical treatment was not reserved, because she had no complications namely perforation and fistulization. We estimated that the onset of intestinal tuberculosis coincided with the acute enterocolitis which she had about one year ago. We realized the importance of paying attention to intestinal tuberculosis in the differential diagnosis of enterocolitis, especially regional enteritis. Furthermore, in the therapy of the immunocompromised host including Down's syndrome, we must pay attention to extra-pulmonary tuberculosis. Efficiency of SM for intestinal tuberculosis with complications was confirmed.  相似文献   
107.
Patients who have undergone allogeneic bone marrow transplantation (allo-BMT) are susceptible to a variety of opportunistic infectious complications in the months to years after engraftment. Impaired in vitro T-cell functions have been documented in these patients, and these T-cell dysfunctions contribute to the prolonged immune deficiency after allo-BMT. In the present study, we examined the expression of CD26 as well as the reconstitution of CD26-mediated T-cell costimulation via the CD3 and CD2 pathways at various times in patients aged greater than 18 years after CD6-positive, T-cell depleted allo- BMT. We found that the percentage of CD26- and CD3-positive cells, as well as the levels of expression of both antigens, was lower than in normal controls during the first 4 months after CD6-depleted allo-BMT. Subsequently, the amount of lymphocytes expressing CD3 and CD26 and the quantitative surface expression of CD3 and CD26 were not significantly different in patients and normal controls. Functional studies showed that CD26-mediated T-cell proliferation via the CD3 pathway was considerably improved and almost reached normal levels by 1 year, whereas recovery of CD26-mediated T-cell proliferation via the CD2 pathway was delayed for at least 2 years after CD6-depleted allo-BMT. As CD26 involvement in the regulation of human thymocyte activation is restricted preferentially to the CD3 pathway--unlike its involvement with both CD3 and CD2 pathways of peripheral T cells--our results suggest that the different effects of CD26-mediated costimulation via the CD3 and CD2 pathways after CD6-depleted allo-BMT may be a reflection of peripheral T-cell immaturity in those individuals, similar to that seen in mature medullary thymocytes or cord T lymphocytes.  相似文献   
108.
Osteoclast (OC) differentiation requires that precursors, such as macrophage colony-stimulating factor (M-CSF)-dependent bone marrow macrophages, receive signals transduced by receptor activator of nuclear factor kappaB (RANK) and c-Fms, receptors for RANK ligand (RANKL) and M-CSF, respectively. Activated c-Fms autophosphorylates cytoplasmic tail tyrosine residues, which, by recruiting adaptor molecules, initiate specific signaling pathways. To identify which tyrosine residues are involved in c-Fms signaling in primary cells, we retrovirally transduced M-CSF-dependent bone marrow macrophages with a chimera comprising the external domain of the erythropoietin (Epo) receptor linked to the transmembrane and cytoplasmic domains of c-Fms. Transduced cells differentiate into bone-resorbing osteoclasts when treated with RANKL and either M-CSF or Epo, confirming that both endogenous and chimeric receptors transmit osteoclastogenic signals. Cells expressing chimeric receptors with Y(697)F, Y(706)F, Y(721)F, and Y(921)F single point mutations generate normal numbers of bone-resorbing OCs, with normal bone-resorbing activity when treated with RANKL and Epo. In contrast, those expressing Y(559)F generate fewer OCs, whereas theY807F mutant is incapable of osteoclastogenesis. Finally, although mature OCs expressing Y(559)F exhibit impaired bone resorption, those bearing Y807F do not. Thus, we have identified specific tyrosine residues in the cytoplasmic tail of c-Fms that are critical for transmitting M-CSF-initiated signals individually required for OC formation or function, respectively.  相似文献   
109.
Background: It has been hypothesized that β‐3 adrenergic receptor and peroxisome proliferator‐activated receptor gamma (PPARγ) might have gene–environmental and gene–gene interactions in periodontal disease. The purpose of this study is to elucidate the interaction between β‐3 adrenergic receptor and PPARγ gene polymorphism with periodontal disease. Methods: Three hundred thirty‐two postmenopausal females were enrolled, and their serum high‐sensitivity C‐reactive protein (hsCRP) and hemoglobin A1c (HbA1c) were examined. β‐3 adrenergic receptor and PPARγ genotypes were then determined. An oral examination was performed. The number of remaining teeth was counted, and the probing depth (PD) and clinical attachment level (CAL) were measured. Prevalence‐rate ratios (PRRs) were calculated by multiple Poisson regression analyses to evaluate the relationship among periodontal disease markers, such as the number of sites with CAL 4 to 5 or ≥6 mm or PD 4 to 5 or ≥6 mm, and β‐3 adrenergic receptor polymorphisms, PPARγ polymorphisms, and the interaction term adjusted by age, hsCRP, and HbA1c, after converting the number of remaining teeth (n) to an offset variable. Results: In the participants with body mass index (BMI) ≥25, PRRs of β‐3 adrenergic receptor genotype (Trp/Arg and Arg/Arg) for periodontal disease markers were 0.13 to 0.70 (P <0.0001 to 0.74), those of PPARγ genotype (Pro/Pro) were 0.66 to 3.14 (P = 0.01 to 0.68), and those of the interaction term for the two genotypes were 1.69 to 12.61 (P <0.0001 to 0.33). However, in the participants with BMI <25, a constant tendency was not observed. Conclusion: The results confirmed a positive relationship between the interaction term for β‐3 adrenergic receptor genotype and PPARγ genotype and various periodontal markers in obese elderly females.  相似文献   
110.
Increased plasma levels of thioredoxin in patients with glucose intolerance   总被引:1,自引:0,他引:1  
OBJECTIVE: The aim of the present study was to determine the effects of glucose intolerance on oxidative stress in patients with coronary artery disease (CAD). METHODS: The patients were divided into 3 groups, diabetes mellitus (DM), IGT or normal glucose tolerance (NGT) according to the criteria of the American Diabetes Association. PATIENTS: The present study consisted of 178 consecutive patients who underwent diagnostic coronary arteriography and a 75-g glucose tolerance test. RESULTS: The level of plasma thioredoxin, a marker of oxidative stress was measured in every patient during the fasting state. The levels of plasma thioredoxin were significantly higher in the DM and IGT groups than the NGT group. Furthermore, we found that there was a positive association between thioredoxin levels and glycosylated hemoglobin (sigma=0.225, p=0.018). In multivariate logistic regression analysis, glucose intolerance (DM or IGT) was only independently associated with the high levels of thioredoxin. The levels of plasma thioredoxin were significantly higher in the CAD group compared to the non-CAD group. In multivariate logistic regression analysis, high levels of thioredoxin, male, age and hypertension were independently associated with the presence of CAD. CONCLUSION: Glucose intolerance was associated with the high levels of thioredoxin. High levels of thioredoxin were related to the presence of CAD. The measurement of thioredoxin as the marker of oxidative stress may be useful for monitoring the development of the cardiovascular diseases.  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