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   13514篇
  免费   989篇
  国内免费   898篇
耳鼻咽喉   10篇
儿科学   252篇
妇产科学   33篇
基础医学   1148篇
口腔科学   1444篇
临床医学   1445篇
内科学   3532篇
皮肤病学   25篇
神经病学   173篇
特种医学   961篇
外科学   1923篇
综合类   2007篇
现状与发展   1篇
预防医学   490篇
眼科学   5篇
药学   1102篇
  5篇
中国医学   331篇
肿瘤学   514篇
  2024年   8篇
  2023年   181篇
  2022年   299篇
  2021年   466篇
  2020年   464篇
  2019年   372篇
  2018年   353篇
  2017年   328篇
  2016年   422篇
  2015年   474篇
  2014年   788篇
  2013年   743篇
  2012年   769篇
  2011年   874篇
  2010年   775篇
  2009年   760篇
  2008年   779篇
  2007年   826篇
  2006年   757篇
  2005年   689篇
  2004年   522篇
  2003年   463篇
  2002年   403篇
  2001年   389篇
  2000年   298篇
  1999年   289篇
  1998年   225篇
  1997年   197篇
  1996年   176篇
  1995年   186篇
  1994年   167篇
  1993年   146篇
  1992年   100篇
  1991年   99篇
  1990年   81篇
  1989年   81篇
  1988年   75篇
  1987年   44篇
  1986年   47篇
  1985年   43篇
  1984年   39篇
  1983年   20篇
  1982年   30篇
  1981年   32篇
  1980年   25篇
  1979年   11篇
  1978年   19篇
  1977年   19篇
  1976年   15篇
  1974年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Objective: Hepatocellular carcinoma (HCC) microenvironment has been recognized as a key contributor for cancer progression, metastasis, and drug resistance. The crosstalk between tumor cells, the vascular endothelial growth factor (VEGF), and the chemokine (C-C motif) ligand 2 (CCL2) signaling networks mediates immunoinhibitory impact and facilitates tumor angiogenesis. The current investigation aimed at exploring the potent anti-cancer activity of the newly designed nano-based anti-cancer therapy comprising anti-VEGF drug, avastin (AV), and CCR2 antagonist (CR) to counteract HCC and tracking its mode of action in vivo. Methods: The prepared AV, CR, and AVCR nanoprototypes were characterized by nanoscale characterization techniques in our previous work. Here, they are applied for unearthing their anti-cancer properties / mechanisms in hepatic cancer-induced rats via analyzing protein levels and genetic expression of the elements incorporated in the angiogenesis, apoptosis, and metastasis signalling pathways. Results: The present results revealed a significant down-regulation in the angiogenesis, survival and metastasis indices along with up-regulation in the pro-apoptotic mediators upon treatment of hepatic cancer-bearing rats with the novel synthesized nanomaterials when compared with the untreated counterparts. We showed across HCC model that anti-VEGF in combination with CCR2 antagonism therapy leads to sensitization and enhanced tumor response over anti-VEGF or CCR2 antagonism monotherapy, particularly in its nanoscale formulation. Conclusion: The present approach provides new mechanistic insights into the powerful anti-hepatic cancer advantage of the novel nanoprototypes which is correlated with modulating critical signal transduction pathways implicated in tumor microenviroment such as angiogenesis, apoptosis and metastasis. This research work presents a substantial foundation for future studies focused on prohibiting cancer progression and recovery by targeting tumor microenviroment.  相似文献   
2.
目的 探索黄芩素调控核苷酸结合寡聚化结构域样受体蛋白 3 ( nucleotide-binding oligomerization domain-like receptor protein 3, NLRP3) / 半胱氨酸天冬氨酸蛋白酶 1 ( cysteine aspartate protease 1, Caspase1) 通路对牙周炎大鼠牙槽骨吸收的影响。 方法 将 40 只牙周炎大鼠随机分为模型组、 黄芩素组、 激活剂 组、 黄芩素 + 激活剂组, 另取 10 只正常作为对照组。 检测大鼠釉牙骨质界到牙槽嵴顶 (CEJ-AC) 的距离、 血清中白细胞介素-6 (IL-6)、 转化生长因子-β (TGF-β) 含量以及牙周组织病理变化、 IL-6、 TGF-β 阳性 表达和 NLRP3、 Caspase-1 蛋白表达。 结果 模型组大鼠 CEJ-AC、 NLRP3、 Caspase-1、 IL-6、 TGF-β 水平及 阳性表达水平以及蛋白表达水平均升高 (P< 0. 05); 经黄芩素干预后, 各项指标均降低 (P< 0. 05); 引入 激活剂明显削弱了黄芩素对牙周炎大鼠的抗炎作用。 结论 黄芩素通过抑制 NLRP3 / Caspase-1 通路减轻炎性反应, 控制牙槽骨吸收。  相似文献   
3.
4.
Over the last 40 years, the incidence and prevalence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have continued to increase. Compared to other epithelial neoplasms in the same organ, GEP-NENs exhibit indolent biological behavior, resulting in more chances to undergo surgery. However, the role of surgery in high-grade or advanced GEP-NENs is still controversial. Surgery is associated with survival improvement of well-differentiated high-grade GEP-NENs, whereas poorly differentiated GEP-NENs that may benefit from resection require careful selection based on Ki67 and other tissue biomarkers. Additionally, surgery also plays an important role in locally advanced and metastatic disease. For locally advanced GEP-NENs, isolated major vascular involvement is no longer an absolute contraindication. In the setting of metastatic GEP-NENs, radical intended surgery is recommended for patients with low-grade and resectable metastases. For unresectable metastatic disease, a variety of surgical approaches, including cytoreduction of liver metastasis, liver transplantation, and surgery after neoadjuvant treatment, show survival benefits. Primary tumor resection in GEP-NENs with unresectable metastatic disease is associated with symptom control, prolonged survival, and improved sensitivity toward systemic therapies. Although there is no established neoadjuvant or adjuvant strategy, increasing attention has been given to this emerging research area. Some studies have reported that neoadjuvant therapy effectively reduces tumor burden, improves the effectiveness of subsequent surgery, and decreases surgical complications.  相似文献   
5.
目的 本研究应用声辐射力脉冲成像(Acoustic Radiation Force Impulse ARFI)技术对慢性乙型肝炎肝硬化患者进行脾脏弹性检测和分析,探讨和对比脾脏ARFI弹性及脾脏ARFI弹性联合血小板计数(Platelet Count PC)在预测乙肝肝硬化食道静脉曲张的临床应用价值。方法 对232例慢性乙型肝炎肝硬化患者应用ARFI技术检测脾脏实时超声弹性,并测量PC,所有患者均于检测前后一周内行胃镜检查明确食管静脉曲张情况,以胃镜结果为金标准,应用受试者工作特征(receiver operating characteristic, ROC)曲线比较脾脏ARFI弹性、PC、及脾ARFI弹性联合PC诊断肝硬化食管静脉曲张的临床价值。结果 食道静脉曲张组脾脏ARFI弹性和PC分别为3.52(3.16-3.87)m/s 和62(41-88.25),无食道静脉曲张组脾脏ARFI弹性和PC分别为2.91(2.35-3.35)m/s和129.5(87.25-196.25)。脾脏ARFI弹性和PC在两组间比较的差异均具有统计学意义(P<0.001 )。单独脾脏ARFI弹性及脾脏ARFI弹性联合PC的ROC曲线下面积分别为0.76和0.83,差异具有统计学意义(P = 0.0021)。结论 脾脏ARFI弹性测值联合PC较单纯脾脏ARFI弹性能更准确的无创预测慢性乙型肝炎肝硬化食管静脉曲张的存在,具有良好的临床应用前景。  相似文献   
6.
7.
目的探究奥美拉唑所引起的不良反应及其与其他药物间的相互作用。方法122例接受奥美拉唑治疗并出现不良反应的患者,分析患者所处的环境状况、情绪状况、过敏史、年龄、过敏体质、生活习惯、饮酒情况等临床资料,探讨不良反应的发生原因,并分析不良反应累及系统分布情况及临床症状、导致不良反应的药物使用类型以及预后情况。结果122例奥美拉唑所致不良反应患者中,男性患者、年龄40~50岁、过敏体质、过敏史、情绪不稳定、药后饮酒、环境状况差占比相对较高。122例患者奥美拉唑所致不良反应中免疫系统占27.87%、消化道系统占23.77%、心脑血管系统占7.38%、神经系统占9.02%、血液系统占21.31%、肝胆系统占10.66%。患者常见临床症状为皮疹、瘙痒、皮炎、过敏性休克、恶心、呕吐、腹泻、心动过速、心律不齐、头晕、头痛、意识模糊、血小板下降、白细胞减少、血尿、肝功能障碍等。奥美拉唑与抗癫痫药苯妥英、抗惊厥药卡马西平、抗焦虑抗癫痫药地西泮以及安替比林药物相互作用,会使机体代谢功能降低,其发生可能与抑制钠离子内流有关。结论奥美拉唑所致不良反应会累及机体多个系统,因此医护人员应加强对患者的问诊,了解患者的相关情况,设计合理的用药方案,减少不良反应的发生。  相似文献   
8.
Hepatic uptake mediated by organic anion transporting polypeptide (OATP) 1B1 and 1B3 can serve as a major elimination pathway for various anionic drugs and as a site of drug-drug interactions (DDIs). This article provides an overview of the in vitro approaches used to predict human hepatic clearance (CLh) and the risk of DDIs involving OATP1Bs. On the basis of the so-called extended clearance concept, in vitro–in vivo extrapolation methods using human hepatocytes as in vitro systems have been used to predict the CLh involving OATP1B-mediated hepatic uptake. CLh can be quantitatively predicted using human donor lots possessing adequate OATP1B activities. The contribution of OATP1Bs to hepatic uptake can be estimated by the relative activity factor, the relative expression factor, or selective inhibitor approaches, which offer generally consistent outcomes. In OATP1B1 inhibition assays, substantial substrate dependency was observed. The time-dependent inhibition of OATP1B1 was also noted and may be a mechanism underlying the in vitro–in vivo differences in the inhibition constant of cyclosporine A. Although it is still challenging to quantitatively predict CLh and DDIs involving OATP1Bs from only preclinical data, understanding the utility and limitation of the current in vitro methods will pave the way for better prediction.  相似文献   
9.
Introduction and aimsCirrhosis is the common outcome of liver diseases. It can be decompensated and lead to the development of complications, such as encephalopathy. Hyperammonemia that develops due to liver dysfunction is etiopathologically related to hepatic encephalopathy. Caffeine increases the activity of the urea cycle in the liver, augmenting ammonia degradation. By antagonizing adenosine receptors, it also has a hepatoprotective effect, impeding the formation of fibrosis, as well as having a stimulating effect on the central nervous system. The present study analyzed the effects of caffeine on the progression of cholestatic liver fibrosis and hepatic encephalopathy.Materials and methodsAn experimental model of cholestatic liver fibrosis, through common bile duct ligature, and of hepatic encephalopathy, through the administration of a high-protein diet, was constructed. Male Wistar rats (n = 32) were equally divided into 4 groups. The experiment lasted 28 days, with the administration of 50 mg/kg/day of caffeine. Laboratory tests, histologic analyses of the liver and encephalon, open field tests (OFTs), and daily behavioral analyses were carried out.ResultsThe ligated animals treated with caffeine had lower mean transaminase levels and improved histologic aspects of the liver and encephalon. The untreated ligated animals were clearly lethargic and apathetic at the last week of the experiment, confirmed by reduced exploratory activity during the OFT.ConclusionCaffeine improved the microarchitecture of the liver and encephalon of the cirrhotic animals and prevented the decrease in exploratory behavior of the animals during the OFT.  相似文献   
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