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   644篇
  免费   66篇
  国内免费   6篇
耳鼻咽喉   4篇
儿科学   18篇
妇产科学   22篇
基础医学   137篇
口腔科学   22篇
临床医学   39篇
内科学   156篇
皮肤病学   49篇
神经病学   44篇
特种医学   7篇
外科学   47篇
综合类   11篇
预防医学   45篇
眼科学   16篇
药学   51篇
中国医学   7篇
肿瘤学   41篇
  2024年   1篇
  2023年   6篇
  2022年   10篇
  2021年   27篇
  2020年   13篇
  2019年   23篇
  2018年   23篇
  2017年   28篇
  2016年   24篇
  2015年   23篇
  2014年   24篇
  2013年   27篇
  2012年   48篇
  2011年   39篇
  2010年   31篇
  2009年   31篇
  2008年   53篇
  2007年   53篇
  2006年   56篇
  2005年   37篇
  2004年   35篇
  2003年   28篇
  2002年   37篇
  2001年   4篇
  2000年   3篇
  1999年   1篇
  1998年   2篇
  1997年   4篇
  1996年   5篇
  1995年   2篇
  1994年   2篇
  1993年   5篇
  1992年   3篇
  1990年   5篇
  1989年   1篇
  1988年   1篇
  1978年   1篇
排序方式: 共有716条查询结果,搜索用时 421 毫秒
31.
OBJECTIVE: The aim of the study was to assess the rate of acceptance of preimplantation genetic diagnosis (PGD) as an alternative to prenatal diagnosis in Lebanese women with previously affected children with homozygous beta-thalassemia. METHODS: Women with a previously affected child attending a nongovernmentally funded thalassemia care center between 1 June 2005 and 31 May 2007 were offered a genetic counseling session. This was followed by administering a questionnaire through direct interview. RESULTS: All 97 women approached accepted to participate in the study (100% response rate). Sixty eight per cent of women considered PGD a better alternative to prenatal diagnosis. The most important perceived advantage of PGD was the avoidance of termination of an affected pregnancy. CONCLUSIONS: PGD is an acceptable alternative to conventional prenatal diagnosis in women at risk of conceiving a child affected with beta-thalassemia. This is particularly true in countries of the Middle-East where therapeutic abortions for fetal indications are prohibited by the law and religion. Copyright (c) 2008 John Wiley & Sons, Ltd.  相似文献   
32.

Background

Most personalized cancer care strategies involving DNA sequencing are highly reliant on acquiring sufficient fresh or frozen tissue. It has been challenging to comprehensively evaluate the genome of advanced prostate cancer (PCa) because of limited access to metastatic tissue.

Objective

To demonstrate the feasibility of a novel next-generation sequencing (NGS)–based platform that can be used with archival formalin-fixed paraffin-embedded (FFPE) biopsy tissue to evaluate the spectrum of DNA alterations seen in advanced PCa.

Design, setting, and participants

FFPE samples (including archival prostatectomies and prostate needle biopsies) were obtained from 45 patients representing the spectrum of disease: localized PCa, metastatic hormone-naive PCa, and metastatic castration-resistant PCa (CRPC). We also assessed paired primaries and metastases to understand disease heterogeneity and disease progression.

Intervention

At least 50 ng of tumor DNA was extracted from FFPE samples and used for hybridization capture and NGS using the Illumina HiSeq 2000 platform.

Outcome measurements and statistical analysis

A total of 3320 exons of 182 cancer-associated genes and 37 introns of 14 commonly rearranged genes were evaluated for genomic alterations.

Results and limitations

We obtained an average sequencing depth of >900X. Overall, 44% of CRPCs harbored genomic alterations involving the androgen receptor gene (AR), including AR copy number gain (24% of CRPCs) or AR point mutation (20% of CRPCs). Other recurrent mutations included transmembrane protease, serine 2 gene (TMPRSS2):v-ets erythroblastosis virus E26 oncogene homolog (avian) gene (ERG) fusion (44%); phosphatase and tensin homolog gene (PTEN) loss (44%); tumor protein p53 gene (TP53) mutation (40%); retinoblastoma gene (RB) loss (28%); v-myc myelocytomatosis viral oncogene homolog (avian) gene (MYC) gain (12%); and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit α gene (PIK3CA) mutation (4%). There was a high incidence of genomic alterations involving key genes important for DNA repair, including breast cancer 2, early onset gene (BRCA2) loss (12%) and ataxia telangiectasia mutated gene (ATM) mutations (8%); these alterations are potentially targetable with poly(adenosine diphosphate-ribose)polymerase inhibitors. A novel and actionable rearrangement involving the v-raf murine sarcoma viral oncogene homolog B1 gene (BRAF) was also detected.

Conclusions

This first-in-principle study demonstrates the feasibility of performing in-depth DNA analyses using FFPE tissue and brings new insight toward understanding the genomic landscape within advanced PCa.  相似文献   
33.
Hepatitis viral infections are important causes of morbidity and mortality in haemodialysis patients. The aim of the present work is to study the prevalence and possible risk factors of hepatitis C virus (HCV), hepatitis B virus (HBV) and dual infection in haemodialysis patients. Three hundred forty patients with end-stage renal disease, 266 males (78.2%) with mean age of 50.9?±?11.6 years and 74 females (21.8%) with mean age of 53.5?±?10.5 years on haemodialysis, were recruited from four haemodialysis units. They were screened for the presence of HCV, HBV and dual HCV and HBV infections and possible risk factors for acquiring these infections in those patients during the period between June 2007 and August 2009. One hundred ninety-six (57.7%) patients were HCV positive while 12 (3.5%) patients had HBV infection. A dual infection with both viruses was observed in 26 patients (7.6%).There was a significant difference in the number of blood transfusions among HCV-positive, HBV-positive and dual infection patients and negative patients (12.4?±?7.6, 13.8?±?6.8, 13.5?±?8.3 vs. 5.2?±?3.4 transfusions, p?<?0.01). HCV, HBV and dual HCV and HBV patients have been on dialysis for a longer period than the negative patients (7.5?±?5, 6.2?±?3.6, 7.5?±?5.4 vs. 4.4?±?4 years, p?<?0.01). Higher HCV was associated with longer haemodialysis duration and history of previous blood transfusion and not associated with dialysis in multicentres. HBV and dual infection is less prevalent than HCV in haemodialysis units.  相似文献   
34.
In the last fifteen years there were several feed-related outbreaks of morbidity and mortality in the Institute's breeding colony of Wistar rats. The last event took place in April 1999, one month after the use of a new supply of the usual standard rodent feed. Animals did not thrive and manifested generalised oedema, hypoalbuminaemia, elevated liver enzymes, and high mortality. The effect of feed was assessed first by feeding a group of sick females during 14 days with either suspected feed (A-March) or with the earlier supply of feed (A-January) of the same producer. Then a group of healthy male rats Y59 from another breeding colony was fed either suspected feed (A-March) or feed from another producer (feed B). Although neither chemical nor microbiological deviation in feed analysis had been detected, decreased consumption and slower body weight gain in all animals fed with feed A-March suggested an association between this batch of feed and the increased morbidity in those animals. Eventually, the entire rat colony was put down and replaced with a new breed which was given a new brand of feed.  相似文献   
35.
The present study describes a monoclonal antibody-based enzyme immunoassay (ELISA) for the quantitation of lipoprotein(a), Lp(a), in human plasma. Two antibodies to Lp(a), 2F4E7 and 8G12G7, were produced and characterized as specific and high affinity antibodies against Lp(a). A reference control serum was utilized to prepare the standard curve in a Lp(a) concentration range from 0.015 to 0.5 ug/ml. A biotinylated monoclonal antibody against apoB-LDL was used as the second antibody. The comparison of the standardized ELISA using mAb 2F4E7 with an ELISA using a characterized mAb against Lp(a) (clone KO9) as capture antibody showed that the Lp(a) concentration of two standard sera was similar with both assays. Furthermore, when compared with an electroimmunoassay kit, similar Lp(a) concentrations for the standard were also obtained.  相似文献   
36.
The cyclin-dependent kinase (cdk) inhibitor p27 preferentially inactivates cdk complexes required for progression through the G1/S transition. Loss of p27 is associated with aggressive behavior in a variety of tumors, including Barrett's associated adenocarcinoma (BAA). We have previously shown that gastroduodenal-esophageal reflux (GDER) together with N-methyl-N-benzylnitrosamine (MBN) induces Barrett's esophagus (BE) and malignant transformation of the esophageal mucosa in mice. This process is enhanced in a p27 null background. Here, we show that chronic flavopiridol administration sharply reduced the prevalence of BE in GDER/MBN-treated p27 knockout mice when compared to animals treated with diluent only (7 vs 26%, P=0.0079). Similarly, flavopiridol reduced the prevalence of BAA (11 vs 32%, P=0.0098) and overall cancer prevalence (15 vs 60%, P<0.0001). In addition, appropriate molecular targeting by flavopiridol in tumor cells was confirmed by downregulation of cyclin D1, a known target of this pan-cdk inhibitor. The results of this study represent the experimental basis for chemoprevention with cdk inhibitors in human BE and BAA.  相似文献   
37.
Psychodermatologic disorders are conditions involving an interaction between the mind and the skin. These disorders fall into three major categories: psychosomatic disorders, primary psychiatric disorders and secondary psychiatric disorders (Koo 1995). The treatment of psychodermatologic disorders is almost impossible without a holistic team approach involving psychiatrist, dermatologist and psychologist. Majority of psychodermatologic disorders can be treated with cognitive-bihevioral psychotherapy, psychoterapeutic stress-and-anxiety-management techniques and psychotropic drugs. Psychopharmacologic treatment with anxiolytics, antidepressants, antipsychotics and mood stabilizers can be prescribed by dermatologist, after consulting the psychiatrist.  相似文献   
38.
Prostate tumor cells preferentially adhere to bone marrow endothelial cells (BMECs) compared with endothelial linings from other tissue microvessels, implicating the importance of BMEC adhesion in the predilection of prostate tumor metastasis to bone. E (endothelial)-selectin, which functions as an initiator of leukocyte adhesion to target tissue endothelium, is constitutively expressed on BMECs, suggesting that prostate tumor cells could use this adhesive mechanism to initiate their migration into bone. In this report, we demonstrate for the first time that human bone-metastatic prostate tumor cells roll on human BMECs under physiological flow conditions. We show that these dynamic adhesive interactions are dependent on the expression of BMEC E-selectin and sialylated glycoconjugates on bone-metastatic prostate tumor cells. We also establish the importance of both glycoprotein(s) and glycosphingolipid structures displaying sialyl Lewis X epitopes as potential E-selectin ligands on bone-metastatic prostate tumor cells. Coexpression of sialylated glycoproteins and glycolipids on bone-metastatic prostate tumor cells triggers robust E-selectin binding activity, which is identical to that observed on human hematopoietic progenitor cells. By Western blot analysis, we identify candidate E-selectin glycoprotein ligand(s); distinct sialyl Lewis X (or HECA-452 antigen)-bearing membrane proteins were resolved at M(r) 130,000 and M(r) 220,000 as well as others ranging from M(r) 100,000 to M(r) 220,000. Immunohistochemical analysis of HECA-452 antigen expression on normal prostate tissue and on low- and high-grade prostate adenocarcinoma shows that HECA-452 antigen expression is directly associated with prostate tumor progression and may indicate acquisition of E-selectin ligand expression. These findings provide novel insight into potential adhesive mechanisms promoting hematogenous dissemination of prostate tumor cells into bone.  相似文献   
39.
OBJECTIVE: We analyzed the causes of deaths among the members of the 4th Guardian Brigade (GB) of the Croatian Army during the war in Croatia from 1991 to 1995: the site of the lethal injuries, the type of wounds, and estimated the severity of injuries with lethal outcome according to the Abbreviated Injury Scale. METHODS: This was a retrospective study using the files and data obtained from 4th GB, Croatian Ministry of Defense, and Croatian Ministry of War Veterans. RESULTS: During the War in Croatia from 1991 to 1995, 182 members of 4th GB were killed. One hundred fifteen (63.2%) suffered lethal injuries caused by shell fragments, 47 (25.8%) soldiers had gunshot wounds, and 20 ( 11.0%) died in traffic accidents. Mean Abbreviated Injury Scale for killed soldiers was 7.61 +/- 1.27. CONCLUSION: During the war in Croatia, the leading causes of death were mines and explosions, and, in a minor proportion, gunshot wounds.  相似文献   
40.
BACKGROUND: The short arm of chromosome 3 is thought to include one or more tumour suppressor genes (TSGs), since carcinoma of various tissues display deletions in this region. Many genes mapping to this region have recently been identified, including the LUCA-15/RBM5 gene. RESULTS: In this study we report the cloning from human bone marrow library of a splice variant of LUCA-15 which lacks exon 6, resulting in a frameshift and producing a truncated protein of 150 amino acids instead of 815 amino acids. This variant is widely expressed at a low level in normal tissues and is expressed at increased levels in T-leukaemic cell lines. Over-expression of this splice variant after electroporation both shortened the cell cycle and inhibited CD95-mediated apoptosis in CEM-C7 T-cells. In marked contrast, over-expression of the full length LUCA-15/RBM5 suppressed cell proliferation both by inducing apoptosis and by extending the G1 phase of the cell cycle. CONCLUSION: These results, taken together with previous observations from ourselves and others, suggest that LUCA-15 is involved in the control of both apoptosis and the cell cycle. Since oncogenesis often relies on separate changes in molecules regulating apoptosis on the one hand, and proliferation, on the other, the discovery of a candidate tumour suppressor gene which affects both processes simultaneously is likely to be of major significance.  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