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   56998篇
  免费   6809篇
  国内免费   2150篇
耳鼻咽喉   430篇
儿科学   626篇
妇产科学   571篇
基础医学   7111篇
口腔科学   1509篇
临床医学   5734篇
内科学   6253篇
皮肤病学   498篇
神经病学   5007篇
特种医学   2064篇
外国民族医学   3篇
外科学   4901篇
综合类   9559篇
现状与发展   8篇
一般理论   2篇
预防医学   7736篇
眼科学   918篇
药学   6357篇
  81篇
中国医学   3423篇
肿瘤学   3166篇
  2024年   118篇
  2023年   1202篇
  2022年   1715篇
  2021年   3019篇
  2020年   2762篇
  2019年   2332篇
  2018年   2213篇
  2017年   2437篇
  2016年   2289篇
  2015年   2575篇
  2014年   4036篇
  2013年   4437篇
  2012年   3524篇
  2011年   3921篇
  2010年   2974篇
  2009年   3092篇
  2008年   3012篇
  2007年   2946篇
  2006年   2494篇
  2005年   2220篇
  2004年   1785篇
  2003年   1603篇
  2002年   1197篇
  2001年   1028篇
  2000年   937篇
  1999年   791篇
  1998年   572篇
  1997年   530篇
  1996年   436篇
  1995年   453篇
  1994年   439篇
  1993年   340篇
  1992年   317篇
  1991年   264篇
  1990年   273篇
  1989年   219篇
  1988年   178篇
  1987年   177篇
  1986年   140篇
  1985年   186篇
  1984年   149篇
  1983年   87篇
  1982年   99篇
  1981年   87篇
  1980年   87篇
  1979年   66篇
  1978年   51篇
  1977年   50篇
  1976年   31篇
  1975年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
目的探讨养阴通脑颗粒主要有效部位(总生物碱、总黄酮、总皂苷、总酚酸)配伍后在脑缺血再灌注模型大鼠体内药物浓度及其药动学与药效学变化。方法采用正交试验法组成上述主要有效部位用量配比不同的9个组方,供脑缺血再灌注模型大鼠ig给药,高效液相色谱-二极管阵列检测器(HPLC-DAD)测定不同时间点血浆中的葛根素、阿魏酸和川芎嗪血浆药物浓度。DAS 3.2.6软件以非房室模型拟合药动学参数,并运用总量统计矩法和综合评分法对整体药动学特征进行评价。同时采用酶联免疫吸附测定(ELISA)法测定大鼠血浆中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的含量。最后进行药动学-药效学(PK-PD)模型研究,获得各药物浓度与药效之间的定量方程。结果葛根素、阿魏酸和川芎嗪在模型大鼠体内的药动学特征有所差异。总量统计矩和综合评分研究表明不同配伍对总量零阶矩、总量平均滞留时间、综合评分等参数影响不一。主要有效部位正交配伍给药后,一定程度上会抑制脑缺血再灌注大鼠血浆中SOD和CAT的降低。各PK-PD模型均采用Sigmoid-Emax模型,拟合结果与实测数据之间相关性良好,R值均大于0.85。结论养阴通脑颗粒主要有效部位配伍对模型大鼠体内的药动学行为和抗氧化指标具有一定影响;中药复方多成分药物代谢动力学可采用总量统计矩和综合评分法进行研究;PK-PD结合模型可用于中药复方多成分药动学与药效学之间相关性的评价与预测。  相似文献   
52.
目的利用翻转课堂教学法改进传统的天然药物化学实验课教学模式,提高该课程的教学效果。方法从实验教学的课程设计与开发,课前自主学习、课中内化及课后评估和讨论等环节进行了一系列的探讨与改革。结果翻转课堂教学模式为解决学生长期以来在天然药物化学实验课中缺乏主动参与性、探索性等问题提供一剂良方。结论在天然药物化学实验课教学中引入翻转课堂教学模式的初步探索为天然药物化学实验课的改革提供了依据和思路。  相似文献   
53.
目的调查消化道肿瘤患者的支持性照顾需求现状并分析其影响因素。方法于2019年1—10月间,采用便利抽样的方法,抽取重庆市三峡中心医院内消化道肿瘤患者共370例,采用一般资料调查表、癌症病人支持性照顾需求简明问卷(SCNS-SF34)、医院焦虑和抑郁量表(HADS)、社会网络支持量表(LSNS)进行问卷调查。以Andersen行为模型为基础,将调查内容中关于消化道肿瘤患者支持性照顾需求的影响因素分别纳入倾向性因素、使能因素和需求性因素中,构建4个线性回归模型进行分析,并检验各模型的拟合优度,采用多元线性回归分析消化道肿瘤患者支持性照顾需求的影响因素。结果共发放问卷370份,回收有效问卷365份,有效回收率为98.6%。365例消化道肿瘤患者支持性照顾需求总均分为(3.42±0.54)分,其中生理与日常生活需求>健康信息需求>照顾与支持需求>心理需求>性需求。多元线性回归分析结果显示:倾向性因素中年龄、婚姻状况,使能因素中的家庭平均月收入、疾病负担能力、社会网络支持,需求性因素中的病程、疾病分期、疼痛情况、焦虑程度、抑郁程度是消化道肿瘤患者支持性照顾需求的主要影响因素(P<0.05)。结论消化道肿瘤患者有较高的支持性照顾需求,其需求受多种因素的影响,建议临床医护人员针对不同需求患者进行针对性满足,并对不同影响因素进行综合考量并加以分类分析。  相似文献   
54.
ObjectiveDiabetic kidney disease (DKD) is the leading cause of death and disability of diabetes mellitus. However, there is still a lack of specific drugs for the treatment of DKD. The chief aim of this research is to investigate the role and mechanism of 2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) for DKD.MethodsWild type and TLR4 knockout mice were induced to diabetes. After 4-week treatment with DMDD, blood sugar, renal function, blood lipid and pathological changes were assessed. Real-time PCR, western blotting, and immunohistochemistry were employed to detect the expressions of TLR4, TGFβ1 and Smad2/3 in the renal tissue.ResultsDMDD improved the serum lipid and decreased fasting blood glucose levels in diabetic mice. CysC and urinary albumin levels increased markedly in the diabetic group, and they were obviously decreased after 4 weeks of DMDD treatment. Compared with the WT diabetic mice, the urinary albumin and CysC in the TLR4-/- mice were expressed at lower levels. HE and Masson’s staining revealed that DMDD clearly ameliorated pathological changes and renal fibrosis. When TLR4 gene was knock out, the pathological was improved. Mechanistically, TLR4, TGF-β1 and Smad2/3 were obvious up-regulation in the renal tissues of diabetic mice. The expressions of these proteins were significantly down-regulated after DMDD treatment (p < 0.05). In the TLR4-/- mice, mRNA and protein levels of TGF-β1 and Smad2/3 were obviously lower than those in the WT mice. In addition, IHC revealed that a strong in situ expressions of TLR4, TGF-β1 and Smad2/3 were seen in the kidney tissues of diabetic mice, which were distinctly weakened in the DMDD-treated mice. In the TLR4-/- mice, however, expressions of TGF-β1 and Smad2/3 were not remarkable increase in the diabetic mice compared with normal mice.ConclusionsThese results strongly indicate that TLR4 is essential for DMDD protection against renal dysfunction in diabetic mice. Its hypoglycemic and anti-fibrosis effects were likely mediated by the TLR4/TGFβ signaling pathway.  相似文献   
55.
Protein phosphatase 4 regulatory subunit 1 (PP4R1) has been shown to play a role in the regulation of centrosome maturation, apoptosis, DNA repair, and tumor necrosis factor signaling. However, the function of PP4R1 in non-small-cell lung cancer remains unclear. In this study, we identify PP4R1 as an oncogene through Oncomine database mining and immunohistochemical staining, and we showed that PP4R1 is upregulated in lung cancer tissues as compared with that in normal lung tissues and correlated with a poor prognosis in lung cancer patients. Furthermore, in vitro study by wound-healing and Transwell assay showed that PP4R1 could promote migration and invasion of lung cancer cells. Mechanistic investigations revealed that PP4R1 could cooperate with high mobility group AT-hook 2 and thereby promotes epithelial-mesenchymal transition via MAPK/extracellular receptor kinase activation. Taken together, our study provides a rich resource for understanding PP4R1 in lung cancer and indicates that PP4R1 may serve as a potential biomarker in lung cancer therapies.  相似文献   
56.

Background

The conventional chemotherapy of colorectal cancer with irinotecan, 5-fluorouracil, and oxaliplatin remains one of the front-line treatments worldwide. However, its efficacy is quite low. Recently studies of the epithelial–mesenchymal transition (EMT) have become the focus of investigations into the cause of chemoresistance in several types of cancer, including colorectal cancer. The data about the role of EMT in chemosensitivity are controversial.

Materials and Methods

Human colon adenocarcinoma cell lines HT29 and HCT116 and 14 primary short-term cultures established from patient tumors were used. The chemosensitivity to irinotecan, 5-fluorouracil, and oxaliplatin was assessed using the (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Immunocytochemistry, immunohistochemistry, and Western blot test were used to investigate the E-cadherin expression, the loss of which is a major hallmark of EMT.

Results

Elevated chemosensitivity of the cell line with EMT phenotype, HCT116, was demonstrated. Increased chemosensitivity was revealed in HT29 cell line upon EMT induction. E-cadherin–positive short-term cultures were more resistant to all the drugs tested, whereas each of E-cadherin–negative cultures showed sensitivity to at least one drug. The statistically significant dependency of cells viability on the E-cadherin expression (P < .04) was demonstrated on the short-term cultures using 2 concentrations of each drug.

Conclusion

The data obtained may serve as a basis for the analysis of colon cancer chemosensitivity using short-term cultures and the assay of E-cadherin expression.  相似文献   
57.
58.
BackgroundThe innovation of immune checkpoint blockade (ICB) represents a promising shift in the treatment of advanced hepatocellular carcinoma (HCC). However, response to ICB has varied largely due to the high tumor heterogeneity and complex tumor microenvironment (TME). The competitive endogenous RNA (ceRNA) network also plays an important role in tumor occurrence and progression, but its relation with tumor-infiltrating immune cells (TICs) remains largely unexplored in HCC. The overriding objective of our study was thus to construct a prognosis-related risk model and to further evaluate the relationship between ceRNA networks and TICs.MethodsDifferentially expressed gene (DEG) analysis was performed to identify the differentially expressed RNAs. Lasso and multivariable Cox regression analyses were used to construct risk models, which were assessed by the area under the receiver operating characteristic curve (AUC of ROC) and Kaplan-Meier (K-M) curves. Then, a single-sample gene set enrichment analysis (ssGSEA) algorithm was adopted to dissect the TICs in HCC samples. Nomograms were constructed and calibration curves were used to verify the discrimination and accuracy of the nomograms. Finally, integration analysis was performed to validate the correlation of ceRNA and TICs.ResultsIn the study, 7 differentially expressed RNAs [5 messenger RNA s (mRNAs) and 2 micro RNAs (miRNAs)] were incorporated to construct a ceRNA risk model. The AUC of the 1-, 3-, and 5-year overall survival (OS) were 0.784, 0.685, and 0.691 respectively. Likewise, 7 types TICs were in the TICs signature model and the AUC of the 1-, 3-, and 5-year OS were 0.706, 0.731, and 0.721 respectively. The integration analysis showed that 7 pairs of mRNA-TICs and 1 pair of miRNA-TICs had a close relation (all correlation coefficients >0.2, P<0.001).ConclusionsThrough constructing two risk models based on ceRNA network and TICs, we identified the hub RNAs and key TICs in the progression and prognosis of HCC, and further explored the relationship between ceRNA and TME. Importantly, targeting these hub RNAs may facilitate the remodeling of the TME and be a potential therapeutic alternative to enhancing the response to ICB, thus improving the prognosis of HCC patients.  相似文献   
59.
Background: Making progressin treatment of all branches of cancers has increasedthe percent of patients that never experience the event of interest. These cases are called immune or cure and models for handling the data included cure fraction rate, are referred to as cure model or long-term survival models. Methods:The data for this historical cohort study, were collected from leukemia patients diagnosed between 2007 to 2014 and followed up until 2016 in Taleghani hospital and received BMT (Bone Marrow Transplant). Some data had to be excluded because of incomplete information. Using recorded files mostly and phone calls rarely, were made to confirm whether the patients were still alive or not. Death due to leukemia was regarded as interested event. Analysis were performed by R version 3.4.1and Stata version 14. Results: Number of recurrents after receiving BMT, pre-transplant Hb and age at diagnosis were found as significant prognostics of survival time. HD patients had the highest 5-years overall survival in category of diagnosis type with 81.3%. Cure fraction was estimated to be 64.1%. Conclusion: According to high percentage of censoring, using long-term model had better fit.  相似文献   
60.
The transition from fetal to newborn life involves a complex series of physiological events that commences with lung aeration, which is thought to involve 3 mechanisms. Two mechanisms occur during labour, Na+ reabsorption and fetal postural changes, and one occurs after birth due to pressure gradients generated by inspiration. However, only one of these mechanisms, fetal postural changes, involves the loss of liquid from the respiratory system. Both other mechanisms involve liquid being reabsorbed from the airways into lung tissue. While this stimulates an increase in pulmonary blood flow (PBF), in large quantities this liquid can adversely affect postnatal respiratory function. The increase in PBF (i) facilitates the onset of pulmonary gas exchange and (ii) allows pulmonary venous return to take over the role of providing preload for the left ventricle, a role played by umbilical venous return during fetal life. Thus, aerating the lung and increasing PBF before umbilical cord clamping (known as physiological based cord clamping), can avoid the loss of preload and reduction in cardiac output that normally accompanies immediate cord clamping.  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