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   2275篇
  免费   89篇
  国内免费   15篇
耳鼻咽喉   39篇
儿科学   103篇
妇产科学   138篇
基础医学   286篇
口腔科学   39篇
临床医学   139篇
内科学   445篇
皮肤病学   58篇
神经病学   199篇
特种医学   50篇
外科学   118篇
综合类   14篇
一般理论   1篇
预防医学   232篇
眼科学   115篇
药学   255篇
中国医学   2篇
肿瘤学   146篇
  2024年   2篇
  2023年   18篇
  2022年   87篇
  2021年   117篇
  2020年   38篇
  2019年   55篇
  2018年   64篇
  2017年   51篇
  2016年   57篇
  2015年   75篇
  2014年   95篇
  2013年   106篇
  2012年   206篇
  2011年   204篇
  2010年   105篇
  2009年   88篇
  2008年   138篇
  2007年   123篇
  2006年   153篇
  2005年   148篇
  2004年   146篇
  2003年   120篇
  2002年   112篇
  2001年   8篇
  2000年   3篇
  1999年   11篇
  1998年   9篇
  1997年   6篇
  1996年   3篇
  1995年   4篇
  1994年   7篇
  1993年   2篇
  1992年   1篇
  1991年   2篇
  1989年   2篇
  1988年   2篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1976年   1篇
  1968年   2篇
  1966年   1篇
排序方式: 共有2379条查询结果,搜索用时 4 毫秒
81.

Background

Undifferentiated embryonal sarcoma of the liver (UESL) represents less than 5% of all malignant hepatic tumors in childhood. It is considered an aggressive neoplasm with an unfavorable prognosis. The aim of this paper is to present a single center experience in the treatment of children with UESL.

Materials and methods

Ten children with UESL were treated between 1981 and 2012. Age at diagnosis ranged from 4 months to 17 years (median age, 6 years and 9 months). Surgery after neoadjuvant chemotherapy (CHT) was performed in 7 patients, and in 3 patients primary surgery was done. Adjuvant chemotherapy was administered in all 10 patients (CYVADIC, CAV, CAV/ETIF/IF + ADM, CDDP/PLADO). Right hemihepatectomy was performed in 1 patient, extended right hemihepatectomy in 6, and partial resection of the right lobe (segments V-VI, segment V) in 2 patients. One patient with unresectable tumor affecting both lobes was listed for liver transplantation (LTx).

Results

Follow-up from diagnosis ranged from 50 to 222 months (mean 138 months). Among 9 patients treated with partial liver resection, distant metastases/local recurrence was not observed in any, and disease-free survival in this group is 100% (9 patients alive). The patient that underwent liver transplantation died of multiorgan failure 4 months postoperatively.However, this patient was misdiagnosed as having hepatoblastoma (HBL) and received PLADO chemotherapy. The overall survival rate is 90%.

Conclusion

Excellent results with long-term survival can be achieved in children with UESL with conventional therapy, including a combination of neoadjuvant and adjuvant chemotherapy and surgery, even in large extensively growing tumors.  相似文献   
82.
We have previously demonstrated that the expression of calcineurin-like phosphoesterase domain containing 1 (CPPED1) decreases in adipose tissue (AT) after weight reduction. However, the function of CPPED1 in AT is unknown. Therefore, we investigated whether the change in CPPED1 expression is connected to changes in adipocyte glucose metabolism. First, we confirmed that the expression of CPPED1 decreased after weight loss in subcutaneous AT. Second, the expression of CPPED1 did not change during adipocyte differentiation. Third, CPPED1 knockdown with small interfering RNA increased expression of genes involved in glucose metabolism (adiponectin, adiponectin receptor 1, and GLUT4) and improved insulin-stimulated glucose uptake. To conclude, CPPED1 is a novel molecule involved in AT biology, and CPPED1 is involved in glucose uptake in adipocytes.Lifestyle modification improves glucose metabolism and results in a substantial reduction in the risk of type 2 diabetes in the long-term (1). In searching new putative genes related to obesity and type 2 diabetes, we have previously demonstrated a multitude of changes in adipose tissue (AT) gene expression in response to weight reduction in individuals with metabolic syndrome (2,3). Among the downregulated genes was calcineurin-like phosphoesterase domain containing 1 (CPPED1) (2); its function in AT is completely unknown.Therefore, we continued to study the role of CPPED1 in AT in more detail. Interestingly, the experiment using a Simpson-Golabi-Behmel syndrome (SGBS) cell strain demonstrated an impact of CPPED1 small interfering RNA (siRNA) on insulin-stimulated glucose uptake in mature adipocytes. Overall, the results demonstrate that CPPED1 is a novel molecule expressed in AT and is related to adipocyte function.  相似文献   
83.
The authors describe the use of bone cement containing calcium phosphate for vertebroplasty of the cavity in the base of odontoid process. A 23-year-old female patient was operated on by incision in lateral cervical area (anterior open access). After a blunt dissection, the working cannula (Kyphon) was introduced under fluoroscopic guidance through the C2 vertebral body to the cavity in the base of the odontoid process. Intraoperatively biopsy of the lesion was taken and histopathological examination excluded the presence of neoplasm. The cavity, presumably haemangioma, was successfully filled with calcium phosphate bone cement KyphOs? FS (Kyphon). The proper filling without paravertebral cement leak was confirmed by postoperative computed tomography (CT). The CT and magnetic resonance imaging performed 9 months after the procedure showed that cement was still present in the cavity. This is the first use of calcium phosphate cement to conduct the vertebroplasty of C2 vertebra.  相似文献   
84.
High-grade gliomas are the most common primary brain tumors. Their malignancy is promoted by the complex crosstalk between different cell types in the central nervous system. Microglia/brain macrophages infiltrate high-grade gliomas and contribute to their progression. To identify factors that mediate the attraction of microglia/macrophages to malignant brain tumors, we established a glioma cell encapsulation model that was applied in vivo. Mouse GL261 glioma cell line and human high-grade glioma cells were seeded into hollow fibers (HF) that allow the passage of soluble molecules but not cells. The glioma cell containing HF were implanted into one brain hemisphere and simultaneously HF with non-transformed fibroblasts (controls) were introduced into the contralateral hemisphere. Implanted mouse and human glioma- but not fibroblast-containing HF attracted microglia and up-regulated immunoreactivity for GFAP, which is a marker of astrogliosis. In this study, we identified GDNF as an important factor for microglial attraction: (1) GL261 and human glioma cells secret GDNF, (2) reduced GDNF production by siRNA in GL261 in mouse glioma cells diminished attraction of microglia, (3) over-expression of GDNF in fibroblasts promoted microglia attraction in our HF assay. In vitro migration assays also showed that GDNF is a strong chemoattractant for microglia. While GDNF release from human or mouse glioma had a profound effect on microglial attraction, the glioma-induced astrogliosis was not affected. Finally, we could show that injection of GL261 mouse glioma cells with GDNF knockdown by shRNA into mouse brains resulted in reduced tumor expansion and improved survival as compared to injection of control cells.  相似文献   
85.
86.
Impaired antiplatelet effect of clopidogrel (CLP) can result from drug-drug interactions and genetic polymorphisms of drug-metabolizing enzymes. The aim of the study was to evaluate the effect of genetic polymorphisms of ABCB1 and the selected cytochrome P450 isoenzymes on the pharmacodynamics and pharmacokinetics of CLP and its metabolites in patients co-treated with atorvastatin or rosuvastatin. The study involved 50 patients after coronary angiography/angioplasty treated with CLP and atorvastatin (n = 25) or rosuvastatin (n = 25) for at least 6 months. Plasma concentrations of CLP, diastereoisomers of thiol metabolite (inactive H3 and active H4), and inactive CLP carboxylic acid metabolite were measured by UPLC-MS/MS method. Identification of the CYP2C19*2, CYP2C19*17, CYP3A4*1G, CYP1A2*1F, and ABCB1 C3435T genetic polymorphisms was performed by PCR-RFLP, while platelet reactivity units (PRU) were tested using the VerifyNow P2Y12 assay. There were significant differences in the pharmacokinetic parameters of the H4 active metabolite of CLP in the atorvastatin and rosuvastatin group divided according to their CYP2C19 genotype. There were no significant associations between CYP3A4, CYP1A2, and ABCB1 genotypes and pharmacokinetic parameters in either statin groups. In the multivariate analysis, CYP2C19*2 genotype and non-genetic factors including BMI, age, and diabetes significantly affected platelet reactivity in the studied groups of patients (P < 0.01). In the atorvastatin group, CYP2C19*2, CYP3A4*1G, and ABCB1 C3435T TT genotypes were independent determinants of PRU values (P < 0.01). The CYP2C19*2 allele is the primary determinant of the exposition to the H4 active metabolite of clopidogrel and platelet reactivity in patients co-treated with atorvastatin or rosuvastatin.  相似文献   
87.
European Archives of Psychiatry and Clinical Neuroscience - The hypothesis of the psychosis continuum enables to study the mechanisms of psychosis risk not only in clinical samples but in...  相似文献   
88.
89.
Rapid and precise phenotyping analysis of large numbers of wild-type and mutant mouse embryos is essential for characterizing the genetic and epigenetic factors regulating embryogenesis. We present a novel methodology that permits precise high-throughput screening of the phenotype of embryos with both targeted and randomly generated mutations. To demonstrate the potential of this methodology we show embryo phenotyping results produced in a large-scale ENU-mutagenesis study. In essence this represents an analysis pipeline, which starts with simultaneous micro-magentic resonance imaging (microMRI) screening (voxel size: 25.4 x 25.4 x 24.4 microm) of 32 embryos in one run. Embryos with an indistinct phenotype are then cut into parts and suspect organs and structures are analysed with HREM (high-resolution episcopic microscopy). HREM is an imaging technique that employs 'positive' eosin staining and episcopic imaging for generating three-dimensional (3D) high-resolution (voxel size: 1.07 x 1.07 x 2 microm) digital data of near histological contrast and quality. The results show that our method guarantees the rapid availability of comprehensive phenotype information for high numbers of embryos in, if necessary, histological quality and detail. The combination of high-throughput microMRI with HREM provides an alternative screening pipeline with advantages over existing 3D phenotype screening methods as well as traditional histology. Thus, the microMRI-HREM phenotype analysis pipeline recommends itself as a routine tool for analysing the phenotype of transgenic and mutant embryos.  相似文献   
90.
Ion channels are vital components of plasma membranes. This article presents an evolutionary view of the biochemical mechanism of controlling activity of ion channels by rigid lipids, such as steroids or biophysically similar molecules, which were instrumental in formation and control of ion channels in cell membranes at the very origin of life. Such regulatory mechanisms exist in all cellular forms of life from ancient bacteria to humans and participate in a diversity of biological functions, from the most basic, such as maintenance of cell shape, homeostasis, feeding, cell fusion, and reproduction to the most intricate, such as the mind. Learning about the regulation of membrane ion channels by steroids and like molecules is important for understanding the evolution of life and various aspects of cell and organism physiology, for unraveling the mysteries of mind, and for practical purposes such as developing new pharmacotherapies.  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