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   403篇
  免费   29篇
  国内免费   10篇
儿科学   15篇
妇产科学   25篇
基础医学   57篇
口腔科学   15篇
临床医学   49篇
内科学   93篇
皮肤病学   8篇
神经病学   25篇
特种医学   4篇
外科学   24篇
综合类   8篇
预防医学   47篇
眼科学   7篇
药学   18篇
中国医学   9篇
肿瘤学   38篇
  2023年   7篇
  2022年   15篇
  2021年   19篇
  2020年   23篇
  2019年   23篇
  2018年   30篇
  2017年   20篇
  2016年   21篇
  2015年   19篇
  2014年   37篇
  2013年   26篇
  2012年   37篇
  2011年   40篇
  2010年   19篇
  2009年   19篇
  2008年   16篇
  2007年   13篇
  2006年   14篇
  2005年   9篇
  2004年   10篇
  2003年   7篇
  2002年   5篇
  2000年   3篇
  1999年   3篇
  1998年   1篇
  1997年   3篇
  1996年   2篇
  1994年   1篇
排序方式: 共有442条查询结果,搜索用时 31 毫秒
41.

Objective

A systematic characterization of hybrid scaffolds, fabricated based on combinatorial additive manufacturing technique and freeze-drying method, is presented as a new platform for osteoblastic differentiation of dental pulp cells (DPCs).

Methods

The scaffolds were consisted of a collagenous matrix embedded in a 3D-printed beta-tricalcium phosphate (β-TCP) as the mineral phase. The developed construct design was intended to achieve mechanical robustness owing to 3D-printed β-TCP scaffold, and biologically active 3D cell culture matrix pertaining to the Collagen extracellular matrix. The β-TCP precursor formulations were investigated for their flow-ability at various temperatures, which optimized for fabrication of 3D printed scaffolds with interconnected porosity. The hybrid constructs were characterized by 3D laser scanning microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and compressive strength testing.

Results

The in vitro characterization of scaffolds revealed that the hybrid β-TCP/Collagen constructs offer superior DPCs proliferation and alkaline phosphatase (ALP) activity compared to the 3D-printed β-TCP scaffold over three weeks. Moreover, it was found that the incorporation of TCP into the Collagen matrix improves the ALP activity.

Significance

The presented results converge to suggest the developed 3D-printed β-TCP/Collagen hybrid constructs as a new platform for osteoblastic differentiation of DPCs for craniomaxillofacial bone regeneration.  相似文献   
42.
Background: Natural killer (NK) cells are the effector cells of innate immunity that respond to infection and tumor. Interactions between killer cell immunoglobulin like receptors (KIR) and human leukocyte antigen (HLA) class I molecules regulate NK cells responses to eliminate infected and transformed cells. Objective: To investigate the impact of KIR genes, HLA ligand genes, and KIR-HLA combinations on susceptibility to tuberculosis (TB) in Lur population of Iran. Methods: The genomic DNA of 50 patients with TB from Lorestan province of Iran was genotyped for sixteen KIR genes and their five major HLA class I ligands were determined by a polymerase chain reaction-sequence-specific primers (PCR-SSP) assay. The results were compared with those of 200 healthy unrelated Iranian individuals. Results: In Lur population of Iran, a significant decrease in frequency of KIR3DS1 was found in TB patients compared to control group (24% vs. 44.5%, OR=0.394, CI=0.194-0.798, p=0.013). Also, among the three activating genes that may use HLA class I molecules as their ligands, a significant decrease was shown in frequency of KIR3DS1 with HLA-B Bw4Ile80 ligand in TB patients compared to control group (4% vs. 23%, OR=0.14, CI=0.033-0.596, p=0.004). Conclusion: These findings imply a genetic imbalance between activating and inhibitory KIR genes and KIR-HLA combinations in Lur TB patients. Low level of activating KIR3DS1 and its combination with HLA-B Bw4Ile80 ligand might have an influence on the susceptibility to TB in Lur population of Iran.  相似文献   
43.
AIM: To investigate the associations of hepatitis B virus (HBV) genotype with HBeAg and anti-HBe status, alanine aminotransferase (ALT) levels and HBV-DNA detection in different groups of HBV-infected patients in southwest Iran. METHODS: A total of 89 HBsAg-positive serum samples were collected from the same number of patients. All sera were then investigated to determine HBV DNA and serological markers. For all the polymerase chain reaction (PCR)-positive samples, biochemical, histopathological assays and genotyping were also performed. RESULTS: Genotype D was the only type of HBV foundin different clinical forms of acute and chronic infections. There was a high prevalence of HBeAg-negative HBV- infected patients with chronic hepatitis (52.7%). Out of 55 patients with chronic hepatitis, seven (12.7%) were diagnosed with cirrhosis. A significant association between the presence of anti-HBe antibody and an increase in ALT level, among either HBeAg-negative (P = 0.01) or HBeAg-positive (P = 0.026) patients, was demonstrated. No significant differences were observed between the clinical outcomes of HBeAg-positive and -negative individuals (P = 0.24). CONCLUSION: Genotype D has been recognized as the only type of HBV found in different clinical forms of HBV infections, including cirrhosis, among the residents of southwest Iran. Anti-HBe possibly plays a role in disease progression in some patients with chronic hepatitis, at least for a period of disease.  相似文献   
44.
Left ventricular diverticula are congenital anomalies and are not as rare as previously thought. In adults, cardiac diverticula are generally accidental findings during imaging modalities, but concomitant disorders might frequently coexist. The pathophysiology, management, prognosis, and natural history of cardiac diverticula remain poorly understood and controversial. Definite diagnosis is often challenging due to similarities in appearance to other more common anomalies such as aneurysms, pseudoaneurysms, endocarditis, cysts, and hypertrophied trabeculations. We herein report a rare case of an adolescent presenting with sinus venosus atrial septal defect, partial anomalous venous connection, and left ventricular diverticula.  相似文献   
45.
Abstract: Evidence from the literature points to the disadvantages encountered by migrant women from non-English-speaking backgrounds in obtaining access to health services. In May 1994, a survey of 31 health units in the metropolitan area and two country areas was conducted in South Australia. The study investigated the services available to women of non-English-speaking background, their level of usage, the factors that affected the use of health services by the women, and the strategies developed by the service providers to overcome the barriers. The study found sexual and reproductive health to be the most important, and occupational health and safety the least important issue for women of non-English-speaking background attending the state's health units. The main problems were English language deficiencies, lack of culturally appropriate services and inadequate knowledge and awareness of the existing services. From the service providers' point of view, language (79 per cent), culture (87 per cent), and information or awareness about health units (78 per cent) were the most important factors affecting title use of health services by women of non-English-speaking background. Women of non-English-speaking background have different linguistic and cultural needs from English-speaking women, and as a result, require specifically designed services.  相似文献   
46.
In a retrospective study of a hospital for the years 1971 -2006, 40 patients with a mucosal melanoma were evaluated with respect to the diagnostics, therapy and prognosis. The results for the survival rate were compared to a study of the DÖSAK with 120 cases. The cumulative 5-year survival rate of 33% (DÖSAK study 35%) emphasizes the unfavorable prognosis for the tumor disease. Age, gender and localization distribution did not show a significant influence on survival. For therapy of the primary tumor and the associated lymph nodes there is an altered surgical concept to maintain the quality of life for affected patients. Tumors should be completely removed and a safety zone of 5 mm with control of the excision edges is sufficient. Resection of bony structures should only be carried out if infiltration has occurred. Extensive resection of the upper and lower jaws should be avoided. A“neck dissection” cannot improve the prognosis and should therefore only be therapeutically carried out if it has been proven that lymph nodes are affected.  相似文献   
47.
Embryotoxic factors existing in maternal sera may influence their effects via specific binding to, or alteration of cell surface molecules in the conceptus. This study was undertaken to determine the effects of sera from women with unexplained recurrent spontaneous abortion (URSA) on cell surface glycoconjugates of the early conceptus. Four cell stage embryos were cultured in medium supplemented with sera from women with URSA, from normal women, or in medium without serum. Developmental competence was assessed as the stage distribution of embryos advancing to during 96 h in culture. Hatched (expanded) blastocysts were stained with wheat germ agglutinin (WGA), peanut agglutinin (PNA) and dolichos biflorus agglutinin (DBA) to detect surface glucoconjugates. We observed that patient sera could be divided into high- and low-risk groups on the basis of the ability to decrease the number of four-cell embryos reaching the expanded blastocyst stage. Furthermore, the intensity of reactivity to PNA changed after exposure to high-risk sera. Morula formation was reduced and blastocyst formation was delayed. Although the sera from women with URSA had embryotoxic effects, no influence on the glycoconjugate patterns were evident in hatched blastocysts, aside from PNA reactivivity. We suggest altered developmental display of PNA-reactive proteins was a biomarker for poor developmental quality due to emrbyotoxic factors in serum from URSA patients.  相似文献   
48.
The use of mesenchymal stem cells (MSCs)-derived equine umbilical cord blood in cell grafts transplantation is advantageous; therefore, preservation of these cells is of utmost importance in repair therapies. To evaluate the viability ratio of the MSCs obtained from equine umbilical cord blood after cryopreservation, umbilical cord blood obtained from nine 46–48-week-old foals were purified for harvesting MCs. The purified cells were frozen from the first to tenth passages and stored in liquid nitrogen. After thawing, the cell viability was assessed through trypan blue staining procedure. The highest viability (>80%) ratio was observed with the cells derived from the first passage in 1 and 8?weeks after cryopreservation. However, the viability of cells was dependent on the passage used for cryopreservation. Results in this study demonstrated that equine umbilical cord blood stem cells could successfully be frozen and stored in liquid nitrogen for 8?weeks without significant change in the characterization of the cells cryopreserved as regards their viability, growth ability, and differentiation potential.  相似文献   
49.
Background: Cystic echinococcosis (CE), also known as echinococcosis/hydatidosis, is one of the most important parasitic diseases in the world. It enhances both humoral and cellular (Th1 and Th2) responses in infected host. Different antigens of the worm may favor the Th1 or Th2 immune responses in CE patients. Objective: To evaluate the humoral and cellular immune responses of Balb/c mice against the crude and excretory/secretory (E/S) antigens of in vitro reared Echinococcus granulosus adult worms. Methods: A total of 20 Balb/c mice divided into 5 groups of 4 mice each. Three groups of mice (n=4) were immunized with crude, E/S and an immunodominant antigen of in vitro reared Echinococcus granulosus adult worms on day 1 and 28. The fourth and the fifth groups were negative control groups and received PBS plus adjuvant, or nothing, respectively. Two weeks after the second injection, the mice were killed and their blood was collected for determining antibody responses, and their spleens were employed for proliferation assay. Total IgG was measured by indirect ELISA. Spleen cells of immunized mice were cultivated and exposed to different antigens of adult worms including E/S and crude antigens. Levels of IFN-γ, IL-12, IL-4 and IL-10 were measured in the recovered cell culture supernatants by capture ELISA. Results: Total IgG assay showed the highest level of antibody produced in mice immunized with crude antigens. Proliferation assay showed a statistically significant production of cytokines in the mice immunized with crude antigens (p<0.05). The highest levels of IFN-γ, IL-12 and IL-4 were produced in mice immunized with crude antigen of the in vitro reared Echinococcus granulosus adult worms followed by E/S antigens. Immunodomonant antigen induced the lowest levels of cytokines (IL-12, IFN-γ, IL-4 and IL-10) in immunized mice. Conclusion: Significant levels of Th1 related cytokines (IFN-γ and IL-12) were produced in Balb/c mice immunized with crude antigen of the in vitro reared Echinococcus granulosus adult worms.  相似文献   
50.
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