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   267190篇
  免费   26569篇
  国内免费   16779篇
耳鼻咽喉   2056篇
儿科学   3578篇
妇产科学   2916篇
基础医学   32842篇
口腔科学   4955篇
临床医学   34804篇
内科学   34219篇
皮肤病学   3117篇
神经病学   11231篇
特种医学   9236篇
外国民族医学   106篇
外科学   23165篇
综合类   51237篇
现状与发展   60篇
一般理论   20篇
预防医学   21561篇
眼科学   6866篇
药学   31049篇
  344篇
中国医学   18075篇
肿瘤学   19101篇
  2024年   845篇
  2023年   3742篇
  2022年   9211篇
  2021年   13165篇
  2020年   10115篇
  2019年   8267篇
  2018年   8605篇
  2017年   8684篇
  2016年   7770篇
  2015年   12137篇
  2014年   15010篇
  2013年   15056篇
  2012年   21873篇
  2011年   23197篇
  2010年   17143篇
  2009年   14091篇
  2008年   16150篇
  2007年   15858篇
  2006年   14225篇
  2005年   12718篇
  2004年   9133篇
  2003年   8688篇
  2002年   7246篇
  2001年   5887篇
  2000年   5025篇
  1999年   4194篇
  1998年   2565篇
  1997年   2710篇
  1996年   1963篇
  1995年   1790篇
  1994年   1638篇
  1993年   1087篇
  1992年   1272篇
  1991年   1175篇
  1990年   1045篇
  1989年   926篇
  1988年   843篇
  1987年   729篇
  1986年   633篇
  1985年   510篇
  1984年   413篇
  1983年   342篇
  1982年   282篇
  1981年   239篇
  1980年   201篇
  1979年   210篇
  1978年   194篇
  1977年   212篇
  1976年   191篇
  1974年   159篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
1. To investigate Genkwa Flos hepatotoxicity, a cell metabolomics strategy combined with serum pharmacology was performed on human HL-7702 liver cells in this study.

2. Firstly, cell viability and biochemical indicators were determined and the cell morphology was observed to confirm the cell injury and develop a cell hepatotoxicity model. Then, with the help of cell metabolomics based on UPLC-MS, the Genkwa Flos group samples were completely separated from the blank group samples in the score plots and seven upregulated as well as two down-regulated putative biomarkers in the loading plot were identified and confirmed. Besides, two signal molecules and four enzymes involved in biosynthesis pathway of lysophosphatidylcholine and the sphingosine kinase/sphingosine-1-phosphate pathway were determined to investigate the relationship between Genkwa Flos hepatotoxicity and these two classic pathways. Finally, the metabolic pathways related to specific biomarkers and two classic metabolic pathways were analyzed to explain the possible mechanism of Genkwa Flos hepatotoxicity.

3. Based on the results, lipid peroxidation and oxidative stress, phospholipase A2/lysophosphatidylcholine pathway, the disturbance of sphingosine-1-phosphate metabolic profile centered on sphingosine kinase/sphingosine-1-phosphate pathway and fatty acid metabolism might be critical participators in the progression of liver injury induced by Genkwa Flos.  相似文献   

92.
Programmed death ligand 1(PD-L1) mediated immune escape play important roles in the development of cancer. The gene polymorphism of PD-L1, in particular rs4143815 C?>?G, has been associated with the cancer risks, but with conflicting results. Therefore, this meta-analysis was aimed to assess the association between rs4143815 C?>?G and cancer susceptibility. A systematic literature search was performed to select the studies and the pooled odds ratio (OR) with 95% confidence interval (CI) was used to evaluate the strength of association. Eleven eligible studies containing 3711 cases and 3704 controls were enrolled in the meta-analysis. The results suggested that there is a strong association between rs4143815 C?>?G and the cancer risks (G vs. C: OR?=?1.386, 95% CI: 1.132–1.696, p?=?0.002; GG vs. CG?+?CC: OR?=?1.843 95% CI: 1.300–2.613, p?=?0.002; GG?+?CG vs. CC: OR?=?1.280, 95% CI: 1.040–1.576, p?=?0.020). Subgroup analysis based on cancer type suggested that PD-L1 rs4143815 C?>?G might increase the susceptibility to gastric cancer (G vs. C: OR?=?1.842, 95% CI: 1.403–2.418, p?<?0.001) and bladder cancer (G vs. C: OR?=?2.015, 95% CI: 1.556–2.608, p?<?0.001), and genotype GG carriers of PD-L1 rs4143815 C?>?G might have higher risks of HCC (GG vs. CG?+?CC: OR?=?2.226 95% CI: 1.562–3.172, p?<?0.001). PD-L1 rs4143815 C?>?G might confer an increased cancer risk, indicating this SNP may contribute to the pathogenesis of cancer and might be used as a potential biomarker to predict the susceptibility to cancer.  相似文献   
93.
Gastric cancer, one of the most common disease, has become a major public health problem worldwide. Cisplatin (DDP) has been a widely used drug for the treatment of cancer, also usually applied in gastric cancer in clinic. However, the side effects including toxicity and drug-resistance restricted the usage of DDP in clinic, so we prepared a DDP-complexed hydrogel (DDP-Gel) and investigated its efficacy in gastric cancer. For in vivo studies, MKN45-Luc cells were injected into BLAB/C node mice subcutaneously to establish gastric cancer with orthotopically grown tumors. Mice bearing tumors were treated with normal saline, DDP and DDP-Gel. Body weight and survival condition were observed and recorded. The treatment efficacy in vivo was detected by luciferase imaging and histological evaluation was performed by H&E staining of different organs. Additionally, normal ICR mice were treated with different doses of DDP/DDP-Gel to calculate their LD50 in vivo. The results showed that DDP-Gel prolonged survival time and ameliorated body weight changes of mice bearing tumors. DDP-Gel exhibited higher efficacy to inhibit tumor growth and metastasis, compared to DDP. Besides, LD50 of DDP-Gel was 166.0?mg/kg, 13.2 folds higher than DDP. As a conclusion, DDP-Gel showed a more effective and safer function than DDP in gastric cancer, which indicating that DDP-Gel might be a novel strategy for gastric cancer therapy.  相似文献   
94.
95.
96.
目的 利用网络药理学和分子对接技术研究石菖蒲抗癫痫的有效成分及作用机制。方法 运用中药系统药理数据库及分析平台检索石菖蒲有效成分及主要靶点,通过GeneCards数据库收集癫痫疾病的相关潜在作用靶点,运用Cytoscape.3.7.1和 String绘制石菖蒲-癫痫靶点互作关系图,运用Metascape数据库进行GO和KEGG信号通路富集分析。运用AutoDock Vina 1.1.2软件对石菖蒲主要有效成分与癫痫相关靶标进行分子对接验证;通过构建戊四唑诱导的癫痫模型初步评价石菖蒲提取物及潜在有效成分的抗癫痫作用。结果 由 TCMSP 筛选得到4个有效成分及76个主要靶点。癫痫疾病以“Score”大于1.5分进行筛选得到3685个靶标。GO富集分析得到BP条目10个,细胞CC条目9个,MF条目10个(P<0.01),主要涉及核受体活性、离子通道活性、激素结合、神经递质受体活性、蛋白激酶活性、钙调蛋白结合等。KEGG 富集得到14条通路,主要涉及c型凝集素受体信号通路、雌激素信号通路、Ca2+信号通路、逆行内源性大麻素信号通路等。分子对接结果显示,桉脂素、山奈酚和8-异戊烯基山奈酚与癫痫关键靶标GABRA2、PPARG等具有良好的结合活性。动物实验结果表明,石菖蒲水提取物及主要潜在有效成分桉脂素和山奈酚在PTZ致小鼠癫痫模型上显示出较好的抗癫痫活性。结论 本研究通过动物实验验证了石菖蒲提取物和潜在有效成分的抗癫痫活性,并且运用网络药理学和分子对接技术探讨了其抗癫痫作用机制,发现石菖蒲可通过多个成分如桉脂素、山奈酚、8-异戊烯基山奈酚,多靶点如GABAA、PPARG等,多条通路如雌激素信号通路、钙信号通路对机体产生协调效应从而抑制癫痫的发作。该研究提示石菖蒲治疗癫痫具有多成分、多靶点、多通路特点,为石菖蒲的进一步研究提供数据支撑。  相似文献   
97.
Neuroscience and Behavioral Physiology - Objective. To determine the frequency, structure, and severity of cognitive impairments in patients with bipolar affective disorder (BAD) in remission....  相似文献   
98.
目的 通过阿霉素(Dox)复制大鼠慢性心力衰竭(CHF)模型,观察Liguzinediol对CHF大鼠心功能的影响。方法 通过血流动力学观察Liguzinediol对Dox(腹腔注射,2 mg/kg)诱导的CHF大鼠左心室内压最大上升/下降速率(±dp/dtmax)、左心室内压(LVSP)、动脉收缩压(ASP)、动脉舒张压(ADP)和心率(HR)的变化;观察Liguzinediol对血清一氧化氮(NO)、一氧化氮合成酶(NOS)、超氧化物歧化酶(SOD)、肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)以及血浆中丙二醛(MDA)的影响。结果 Liguzinediol能增加LVSP、+dp/dtmax、ASP、ADP、AP、HR,降低-dp/dtmax(P<0.05~0.01);降低NO、iNOS以及MDA的浓度,同时增强了SOD的活性(P<0.05~0.01);抑制IL-6和TNF-α的生成(P<0.05~0.01)。结论 Liguzinediol可明显改善Dox诱导的CHF大鼠血流动力学指标,减少模型大鼠炎症因子的释放以及抑制氧自由基的生成。   相似文献   
99.
100.
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