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   41966篇
  免费   3170篇
  国内免费   2088篇
耳鼻咽喉   398篇
儿科学   885篇
妇产科学   873篇
基础医学   8639篇
口腔科学   739篇
临床医学   3421篇
内科学   7228篇
皮肤病学   477篇
神经病学   2591篇
特种医学   757篇
外国民族医学   6篇
外科学   3607篇
综合类   6740篇
现状与发展   5篇
预防医学   2361篇
眼科学   540篇
药学   3247篇
  4篇
中国医学   477篇
肿瘤学   4229篇
  2024年   17篇
  2023年   267篇
  2022年   583篇
  2021年   877篇
  2020年   862篇
  2019年   766篇
  2018年   926篇
  2017年   1056篇
  2016年   1203篇
  2015年   1412篇
  2014年   2159篇
  2013年   2514篇
  2012年   2522篇
  2011年   2934篇
  2010年   2504篇
  2009年   2564篇
  2008年   2893篇
  2007年   3023篇
  2006年   2977篇
  2005年   2682篇
  2004年   2274篇
  2003年   1996篇
  2002年   1606篇
  2001年   1392篇
  2000年   1140篇
  1999年   923篇
  1998年   663篇
  1997年   611篇
  1996年   370篇
  1995年   361篇
  1994年   258篇
  1993年   175篇
  1992年   122篇
  1991年   118篇
  1990年   90篇
  1989年   87篇
  1988年   70篇
  1987年   35篇
  1986年   46篇
  1985年   37篇
  1984年   18篇
  1983年   7篇
  1982年   19篇
  1981年   12篇
  1980年   13篇
  1979年   12篇
  1978年   5篇
  1976年   5篇
  1971年   4篇
  1906年   2篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
AIM: To investigate the association between interleukin-10 (IL-10) genetic polymorphisms and risk of POAG through a case-control study in a Han population of China. METHODS: A total of 210 patients with POAG and 420 normal subjects were recruited during the period from Dec. 2013 to Dec. 2016. The IL-10 -1082A>G (rs1800870), -819T>C (rs1800871) and -592C>A (rs1800872) polymorphisms were determined using iPlex GOLD SNP genotyping analysis (the SequenomMassARRAY® System, Sequenom, San Diego, USA). The association between IL-10 -1082A>G (rs1800870), -819T>C (rs1800871), and -592C>A (rs1800872) polymorphisms and risk of POAG was assessed by singlelogistic regression analysis. RESULTS: We observed that those carrying the CC genotype of rs1800871 was associated with an increased risk of POAG when compared with those harboring the TT genotype (OR=1.84, 95%CI=1.01-3.38). Those with AA genotype of rs1800872 had a 10.62 fold risk of POAG in comparison to the CC genotype (OR=10.62, 95%CI, 3.41-33.09). A completely linkage disequilibrium was found between IL-10 rs1800871-rs1800872 (D’=1.00, r2=0.16). The A-C-A (OR=2.60, 95%CI, 1.48-4.58) and G-T-A (OR=2.34, 95%CI, 1.42-3.86) haplotypes were associated with an increased risk of POAG, while the A-T-C haplotype showed a decreased risk of POAG (OR=0.63, 95%CI, 0.49-0.81). CONCLUSION: Our data suggest that IL-10 rs1800871 and rs1800872 can be predictive factors for the pathogenesis of POAG in the Chinese population.  相似文献   
992.
目的 探讨白细胞介素-10(IL-10)基因位点-1082A/G、-819C/T和-592C/A多态性与IL-10水平及儿童肠道病毒71型(EV71)感染程度的关系。方法 选取EV71感染的手足口病患儿137例为研究对象,其中轻症组91例,重症组46例,另选取行健康体检儿童122例为健康对照组,采集临床数据。采用酶联免疫吸附试验(ELISA)检测血清IL-10水平。采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析技术检测IL-10基因位点-1082A/G、-819C/T和-592C/A的多态性。结果 与健康对照组相比,EV71感染组患儿的-1082位点AA基因型频率和A等位基因频率更高(P < 0.05)。在EV71感染组中,重症组-1082位点AA基因型频率和A等位基因频率高于轻症组(P < 0.05)。两组间IL-10基因位点-819C/T和-592C/A多态性的分布比较差异均无统计学意义(P > 0.05)。重症组患儿血清IL-10水平明显高于轻症组和健康对照组(P < 0.05)。IL-10-1082 AA基因型、-819 TT基因型和-592 AA基因型与IL-10的低表达有关(P < 0.05)。在单倍型构建上,EV71感染组GCC单倍型的频率低于健康对照组(P < 0.05)。在EV71重症感染组中,ATA单倍型患儿的IL-10水平较其他单倍型显著降低,而GCC患儿的IL-10水平较其他单倍型显著升高(P < 0.05);轻症组和健康对照组各单倍型间的IL-10水平比较差异无统计学意义(P > 0.05)。结论 IL-10基因多态性与IL-10表达水平及EV71感染严重程度有关。  相似文献   
993.
994.
The overexpression of cyclooxygenase-2 (COX-2) was correlated with the invasion and lymphatic metastasis and with the clinical stage of Nasopharyngeal carcinoma (NPC). The C allele of COX-2 gene rs5275 polymorphism disrupts miR-542-3p function to promote COX-2 overexpression. To examine the role of COX-2 gene rs5275 polymorphism in NPC, we determined COX-2 gene rs5275 polymorphism by using a custom-by-design 48-Plex single nucleotide polymorphism (SNP) Scan? Kit. We found that C allele or CC genotype of rs5275 polymorphism in COX-2 gene was associated with an increased risk of NPC. In stratified analyses, COX-2 gene rs5275 polymorphism was associated with the risk of NPC among females, smokers, and drinkers. Based on these results, we concluded that COX-2 gene rs5275 variant contributes to NPC risk in a Chinese population. Larger studies with more diverse ethnic populations are needed to confirm these results.  相似文献   
995.
Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. FGR pregnancies are often associated with histological evidence of placental vascular thrombosis. The proteoglycans are important components and regulators of vascular homeostasis. Previous studies from our laboratory highlighted mRNA and protein expression differences in placental proteoglycan decorin (DCN), within a clinically well-characterised cohort of third-trimester idiopathic FGR compared with gestation-matched uncomplicated control pregnancies. We also showed that decorin contributes to abnormal angiogenesis and increased thrombin generation in vitro. These observations suggest that DCN gene expression may contribute to the etiology of FGR. Small for gestational age (SGA) is frequently used as a proxy for FGR and is defined as a birth weight below the 10th percentile of a birth weight curve. We therefore made use of a unique resource of first trimester tissues obtained via chorionic villus sampling during the first trimester to investigate the temporal relationship between altered DCN expression and any subsequent development of SGA. We hypothesized that placental DCN expression is decreased early in gestation in SGA pregnancies. Surplus chorionic villus specimens from 15 women subsequently diagnosed with FGR and 50 from women with uncomplicated pregnancies were collected. DCN mRNA and DCN protein were determined using real-time PCR and immunoblotting, respectively. Both DCN mRNA and protein were significantly decreased in placentae from first-trimester SGA-pregnancies compared with controls (p < 0.05). This is the first study to report a temporal relationship between altered placental DCN expression and subsequent development of SGA.  相似文献   
996.
Mechanical loading is an essential environmental factor in skeletal homeostasis, but the response of osteoblast-associated genes to mechanical osteogenic signal is largely unknown. This study uses our recently characterized in vivo osteoinductive model to analyze the sequence of stimulation and the time course of expression of osteoblast-associated genes in mechanically loaded mouse periodontium. Temporal pattern of regulation of osteocalcin (OC), alkaline phosphatase (ALP), and type I collagen (collagen I) was determined during mechanically-induced osteoblast differentiation in vivo, using a mouse tooth movement model earlier shown to induce bone formation and cell-specific regulation of genes in osteoblasts. The expression of target genes was determined after 1, 2, 3, 4, and 6 days of orthodontic movement of the mouse first molar. mRNA levels were measured in the layer of osteoblasts adjacent to the alveolar bone surface, using in situ hybridization and a relative quantitative video image analysis of cell-specific hybridization intensity, with non-osseous mesenchymal periodontal cells as an internal standard. After 24 hours of loading, the level of OC in osteoblasts slightly decreased, followed by a remarkable 4.6-fold cell-specific stimulation between 1 and 2 days of treatment. The high level expression of OC was maintained throughout the treatment with a peak 7-fold stimulation at day 4. The expression of collagen I gene was not significantly affected after 1 day, but it was stimulated 3-fold at day 2, and maintained at a similar level through day 6. The ALP gene, which we previously found to be mechanically stimulated during the first 24 hours, remained enhanced from 1.8- to 2.2-fold throughout the 6 days of treatment. Thus, in an intact alveolar bone compartment, mechanical loading resulted in a defined temporal sequence of induction of osteoblast-associated genes. Stimulation of OC 48 h after the onset of loading (and 24 h prior to deposition of osteoid) temporally coincided with that of collagen I, and was preceded for 24 h by an enhancement of ALP. Identification of OC as a mechanically responsive gene induced in functionally active osteoblasts in this study is consistent with its potential role in limiting the rate of mechanically-induced bone modeling. Furthermore, these results show that temporal progression of mechanically-induced osteoblast phenotype in this in vivo model occurs very rapidly. This suggests that physiologically relevant mechanical osteoinductive signal in vivo is targeting a population of committed osteoblast precursor cells that are capable of rapidly responding by entering a differentiation pathway and initiating an anabolic skeletal adaptation process.  相似文献   
997.
Primary immune thrombocytopenia (ITP) of childhood is an autoimmune disease characterized by abnormally increased destruction of platelets and decreased megakaryopoiesis. Stromal‐derived factor‐1 (SDF‐1) plays a role in megakaryopoiesis and may be involved in the pathogenesis of ITP. Five single nucleotide polymorphisms (SNPs) of the SDF‐1 gene, including rs1801157, rs2839693, rs2297630, rs1065297, and rs266085, were assessed in 100 children with ITP and 126 healthy controls. The genotypes were analyzed by tetra ARMS polymerase chain reaction and confirmed by direct sequencing. Compared with controls, the rs2839693 A/A and rs266085 C/T genotypes were decreased in ITP patients (P = 0.004 and 0.007, respectively). The odds ratios of the latter genotypes were 0.48, 95% CI 0.28–0.82. Further analysis of the relationship between SDF‐1 polymorphisms and clinical features showed that rs2297630 A/G was associated with protection from chronicity (P = 0.002; OR, 0.07; 95% CI, 0.01–0.61) and steroid dependence (P = 0.007; OR, 0.10; 95% CI, 0.01–0.84) in ITP patients. However, rs266085 genotype C/C was associated with risk of steroid dependence (P = 0.012, OR 3.87, 95% CI 1.27–11.77). The findings of this study suggest that SDF‐1 gene variations may be associated with the occurrence and prognosis of childhood ITP.  相似文献   
998.
《Drug metabolism reviews》2012,44(4):553-624
The aldo-keto reductase (AKR) superfamily comprises enzymes that catalyze redox transformations involved in biosynthesis, intermediary metabolism, and detoxification. Substrates of AKRs include glucose, steroids, glycosylation end-products, lipid peroxidation products, and environmental pollutants. These proteins adopt a (β /α )8 barrel structural motif interrupted by a number of extraneous loops and helixes that vary between proteins and bring structural identity to individual families. The human AKR family differs from the rodent families. Due to their broad substrate specificity, AKRs play an important role in the phase II detoxification of a large number of pharmaceuticals, drugs, and xenobiotics.  相似文献   
999.
BackgroundThe cost-effectiveness of the 70-gene signature (70-GS) (MammaPrint®) has earlier been estimated using retrospective validation data. Based on the prospective 5-year survival data of the microarRAy-prognoSTics-in-breast-cancER (RASTER) study, the aim here was to evaluate the cost-effectiveness reflecting the actual use in clinical practice, including reality-based compliance rates.MethodsCosts and outcomes (quality-adjusted-life-years (QALYs)) were calculated in node-negative (N?) patients included in the RASTER study (n = 427). Sensitivity and specificity of the 70-gene and Adjuvant! Online (AO) were based on 5-year distant-disease-free survival (DDFS). Subgroup analyses were performed for two groups for whom benefit of the 70-gene had earlier been reported: (1) ductal, oestrogen receptor-positive (ER+), tumour diameter 10–30 mm, grade II, age 40–70; (2) ductal, oestrogen receptor-positive, tumour diameter 5–30 mm, grade II/III and age 40–70.ResultsBased on 5-year survival data, the cost-effectiveness of the 70-gene signature versus AO was prospectively confirmed. The total health care costs per patient were €26,786 for the 70-gene and €29,187 for AO. The quality adjusted life years yielded 12.49 and 11.88, respectively. The subgroups retrieved slightly higher life gains and higher costs, but all resulted finally in a favourable position for the 70-gene signature.ConclusionsThe use of the 70-gene signature, as judged appropriate by doctors and patients and supported by a low risk 70-gene signature as an oncological safe choice, was also found to be cost-effective.  相似文献   
1000.
Gene transfer offers a potential way to correct local and systemic protein deficiency disorders by using genes as drugs, so called gene therapeutics. Salivary glands present an interesting target site for gene therapeutic applications. Herein, we review proofs of concept achieved for salivary glands with in vivo animal models. In that context we discuss problems (general and salivary tissue-specific) that limit immediate clinical use for this application of gene transfer. Ongoing efforts, however, suggest that salivary glands may be suitable as gene therapeutic target sites for drug delivery in the near future.  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