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   14674篇
  免费   1438篇
  国内免费   492篇
耳鼻咽喉   103篇
儿科学   256篇
妇产科学   164篇
基础医学   2260篇
口腔科学   1045篇
临床医学   1632篇
内科学   2273篇
皮肤病学   194篇
神经病学   754篇
特种医学   481篇
外国民族医学   2篇
外科学   1183篇
综合类   1556篇
现状与发展   4篇
预防医学   1205篇
眼科学   172篇
药学   1595篇
  5篇
中国医学   515篇
肿瘤学   1205篇
  2024年   33篇
  2023年   264篇
  2022年   757篇
  2021年   1063篇
  2020年   623篇
  2019年   646篇
  2018年   595篇
  2017年   614篇
  2016年   572篇
  2015年   728篇
  2014年   986篇
  2013年   1132篇
  2012年   746篇
  2011年   833篇
  2010年   625篇
  2009年   588篇
  2008年   609篇
  2007年   518篇
  2006年   414篇
  2005年   389篇
  2004年   377篇
  2003年   347篇
  2002年   289篇
  2001年   241篇
  2000年   199篇
  1999年   176篇
  1998年   210篇
  1997年   171篇
  1996年   191篇
  1995年   173篇
  1994年   121篇
  1993年   112篇
  1992年   122篇
  1991年   115篇
  1990年   87篇
  1989年   78篇
  1988年   81篇
  1987年   74篇
  1986年   60篇
  1985年   92篇
  1984年   94篇
  1983年   64篇
  1982年   58篇
  1981年   60篇
  1980年   46篇
  1979年   66篇
  1978年   40篇
  1977年   35篇
  1976年   40篇
  1975年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的 探讨右美托咪定联合综合体温保护对腔镜手术治疗老年恶性肿瘤患者苏醒期质量及免疫功能的影响。方法 选择择期行腔镜手术治疗的老年恶性肿瘤患者90例,随机均分为3组:对照组(C组)、体温保护组(T组)和体温保护联合右美托咪定组(T-D组),每组30例。C组常规体温保护,T组和T-D组综合体温保护;T-D组麻醉诱导前10 min泵注右美托咪定0.5 μg/kg。记录3组患者麻醉诱导开始时(T0)、手术开始30 min(T1)、60 min(T2)、90 min(T3)、120 min(T4)以及手术结束时(T5)的鼻咽温度;于T0、术后2 h(T6)、24 h(T7)和48 h(T8)时抽取静脉血标本,测定T淋巴细胞亚群(CD3+、CD4+和CD8+)和自然杀伤细胞(NK cell)水平;记录患者术中麻醉药物用量及苏醒期质量指标。结果 与T0比较,C组T2~T5时点鼻咽温度均明显降低(P < 0.05);与C组比较,T组和T-D组T2~T5时点鼻咽温度明显升高(P < 0.05)。与T0时点比较,C组、T组和T-D组T6、T7和T8时点CD3+和NK cell活性均明显降低(P < 0.05);C组在T6、T7和T8时点,T组和T-D组在T6和T7时点,CD4+活性均明显降低(P < 0.05)。与C组比较,T组和T-D组T6和T7时点CD3+细胞活性均明显升高(P < 0.05);T组在T7时点,T-D组在T6和T7时点,CD4+细胞活性均明显升高(P < 0.05);T组在T7时点,T-D组在T6、T7和T8时点,NK cell活性均明显升高(P < 0.05)。结论 采用体温保护措施联合右美托咪定能够维持老年恶性肿瘤患者的体温稳定,减少围手术期意外低体温(IPH)的发生,并有效提高患者苏醒期质量,减轻免疫抑制程度,加速患者早期恢复。  相似文献   
2.
Abstract

Background: Cerebral palsy (CP) is a common childhood disability. However, these individuals are now living longer lives, participating in adult roles, and seeking healthcare services. The transition from pediatric to adult healthcare for adolescents with CP is a challenging yet significant time. Adolescents experience several barriers during transition.

Objectives: To utilize the environmental and personal dimensions of the ICF model in order to explore barriers when transitioning to adulthood as well as discuss characteristics and physical therapy implications needed to succeed within transition.

Methods: Electronic searching of PubMed, CINAHL, ERIC, Scopus, ProQuest, and the Cochrane Library databases was concluded on January 9, 2019 for studies including transition between pediatric and adult healthcare in individuals diagnosed with CP. Two independent reviewers agreed upon inclusion, eligibility, and quality assessment of each study using the Mixed-Methods Appraisal Tool (MMAT).

Results: Seven studies were included in the systematic review. Results for each study were separated based on the personal and environmental contextual factors of the ICF model and solutions to the barriers were then discussed.

Conclusions: Research has provided proposed solutions to select barriers, however, other barriers have yet to be addressed. More research is needed to address these barriers and provide a model program that can be implemented within the healthcare systems to promote a successful transition for adolescents with CP from pediatric to adult services.  相似文献   
3.
Concrete plants accumulate large amounts of concrete wash water. This water, which pH is highly alkaline, has a negative impact on the environment. Its reuse in fresh concrete slightly reduces its mechanical properties. The combination of concrete wash water and zeolitic by-product led to an increase of 4.6% in the compressive strength at 7 days hydration and up to 30% at 28 days hydration. The same combination led to the denser microstructure compared to the samples made with concrete wash water. This could be explained by the pozzolanic reaction of the zeolitic by-product. The complex chemical reactions of cement, zeolitic by-product, and fines presented in the concrete wash water occurred. Therefore, it was suggested the reusing method of concrete wash water together with zeolitic by-product in the fresh concrete mixtures by substituting some amount of tap water with concrete wash water. In this way, the consumption of tap water is possible to reduce in cement systems.  相似文献   
4.
Abstract

Objective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.

Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.

Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.

Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings.  相似文献   
5.
Profilin 1 (PFN1) is a critical actin-regulatory protein; however, its functional role in hepatocellular carcinoma (HCC) progression remains to be further elucidated. In the present study, we observed that the expression levels of PFN1 were significantly decreased in HCC tissues and cell lines. Low PFN1 expression was significantly correlated with aggressive clinicopathological characteristics and poor prognosis of HCC patients. Further in vitro experiments demonstrated that overexpression of PFN1 remarkably inhibited the proliferation, migration, invasion and EMT of HCC cells. Moreover, we also found that PFN1 was a direct target gene of miR-19a-3p, and in HCC tissues, and there was a significantly inverse correlation between PFN1 mRNA and miR-19a-3p expression. Collectively, our results showed that PFN1 functions as a tumor suppressor in HCC, and might serve as a diagnostic and therapeutic target for HCC patients.  相似文献   
6.
7.
Helicobacter pylori (H. pylori) is a main risk factor for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is involved in the development and progression of H. pylori-associated GC. However, the exact molecular mechanism of this process remains unclear. The AKT/GSK3β signaling pathway has been demonstrated to promote EMT in several types of cancer. The present study investigated whether H. pylori infection induced EMT, and promoted the development and metastasis of cancer in the normal gastric mucosa, and whether this process was dependent on AKT activation. The expression levels of the EMT-associated proteins, including E-cadherin and N-cadherin, were determined in 165 gastric mucosal samples of different disease stages by immunohistochemical analysis. The expression levels of E-cadherin, N-cadherin, AKT, phosphorylated (p-)AKT (Ser473), GSK3β and p-GSK3β (Ser9) were further determined in H. pylori-infected Mongolian gerbil gastric tissues and cells co-cultured with H. pylori by immunohistochemical analysis and western blotting. The results indicated that the expression levels of the epithelial marker E-cadherin were decreased, whereas the expression levels of the mesenchymal marker N-cadherin were increased during gastric carcinogenesis. Their expression levels were associated with H. pylori infection. Furthermore, H. pylori infection resulted in downregulation of E-cadherin expression and upregulation of N-cadherin expression in Mongolian gerbils and GES-1 cells. In addition, an investigation of the associated mechanism of action revealed that p-AKT (Ser473) and p-GSK3β (Ser9) were activated in GES-1 cells following co-culture with H. pylori. Furthermore, following pretreatment of the cells with the AKT inhibitor VIII, the expression levels of E-cadherin, N-cadherin, p-AKT and p-GSK3β did not show significant differences between GES-1 cells that were co-cultured with or without H. pylori. The levels of p-AKT and p-GSK3β were increased in H. pylori-infected Mongolian gerbils. In conclusion, the present study demonstrated that H. pylori infection activated AKT and resulted in the phosphorylation and inactivation of GSK3β, which in turn promoted early stage EMT. These effects were AKT-dependent. This mechanism may serve as a prerequisite for GC development.  相似文献   
8.
目的: 探讨育龄、绝经过渡期子宫肌瘤患者异常阴道出血危险因素,为异常阴道出血临床精准诊断、治疗提供理论依据。方法: 选取2017年06月—2020年06月于内蒙古医科大学附属医院住院行手术治疗的子宫肌瘤患者。实验组设为非月经期异常阴道出血的子宫肌瘤患者,对照组为无异常阴道流血子宫肌瘤患者。根据第9版教科书年龄18-43岁定为育龄组;44-54岁定为绝经过渡期组(我国妇女平均绝经年龄为49.5岁,80%在44-54岁之间〔1〕)。 应用Excel双录入,核对无误后进行统计分析。计数资料的比较用R×C列联表卡方检验、四格表卡方检验及两独立样本秩和检验。非条件Logistic回归模型用于子宫肌瘤阴道异常出血危险因素的分析,并分别得到OR值与相应95%的可信区间。在此模型中,OR值>1认为是危险因素,OR值<1认为是保护因素。统计学显著性水平设定为双侧p≤0.05,即认为差异有统计学意义。全部统计分析选用SPSS19.0软件进行统计学分析。结果:1.将与子宫肌瘤阴道异常出血相关的33项临床指标纳入单因素分析得出,月经周期异常、肌瘤位置(子宫颈肌瘤)、肌瘤直径≥9cm、血红蛋白异常、子宫内膜癌、核分裂像>5个差异有统计学意义(P≤0.05),均是子宫肌瘤阴道异常出血的危险因素;2.子宫肌瘤异常阴道出血核分裂像>5个与子宫内膜病理性改变和异常阴道出血差异有统计学意义(P=0.019)。结论:1. 子宫内膜发生病理改变是子宫肌瘤患者引起异常阴道出血的原因之一。2.月经周期异常、子宫颈肌瘤、肌瘤直径≥9cm、血红蛋白异常、子宫内膜病理改变均是子宫肌瘤阴道异常出血的危险因素;子宫肌瘤核分裂像>5个是子宫平滑肌瘤出现异常阴道出血的独立高危因素;3.子宫肌瘤核分裂像>5与阴道出血、子宫内膜病理改变有统计学意义。进行单因素分析后得知,月经周期、肌瘤位置、肌瘤大小、血红蛋白、子宫内膜病理变化均子宫肌瘤阴道异常出血的发生有关。 关键词育龄;绝经过渡期;子宫平滑肌瘤;异常阴道出血;危险因素  相似文献   
9.
10.
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