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   15442篇
  免费   1030篇
  国内免费   305篇
耳鼻咽喉   377篇
儿科学   163篇
妇产科学   167篇
基础医学   2453篇
口腔科学   182篇
临床医学   1256篇
内科学   3182篇
皮肤病学   623篇
神经病学   1115篇
特种医学   932篇
外国民族医学   3篇
外科学   2067篇
综合类   252篇
一般理论   7篇
预防医学   498篇
眼科学   422篇
药学   1453篇
  3篇
中国医学   289篇
肿瘤学   1333篇
  2024年   17篇
  2023年   111篇
  2022年   412篇
  2021年   564篇
  2020年   303篇
  2019年   441篇
  2018年   509篇
  2017年   417篇
  2016年   613篇
  2015年   895篇
  2014年   1020篇
  2013年   1064篇
  2012年   1625篇
  2011年   1533篇
  2010年   945篇
  2009年   802篇
  2008年   995篇
  2007年   898篇
  2006年   775篇
  2005年   705篇
  2004年   544篇
  2003年   447篇
  2002年   393篇
  2001年   116篇
  2000年   76篇
  1999年   78篇
  1998年   66篇
  1997年   62篇
  1996年   34篇
  1995年   30篇
  1994年   32篇
  1993年   18篇
  1992年   32篇
  1991年   27篇
  1990年   18篇
  1989年   23篇
  1988年   7篇
  1987年   12篇
  1986年   14篇
  1985年   10篇
  1984年   16篇
  1983年   12篇
  1982年   7篇
  1981年   12篇
  1980年   6篇
  1979年   8篇
  1978年   4篇
  1977年   5篇
  1976年   6篇
  1974年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
【摘要】 目的 研究老年高血压患者的血压昼夜节律变化对左室肥厚的影响。方法 选取我院126例高血压患者,根据心脏彩超提示左室肥厚情况分为肥厚组(n=52例)和非肥厚组(n=74例)。比较两组动态血压指标及血压变异性,进行多因素分析探讨血压变异性对左室肥厚的影响。 结果 高血压肥厚组24h平均收缩压(24hSBP)、白天平均收缩压(dSBP)、夜间平均收缩压(nSBP)、24h收缩压标准差(24hSSD)、24h舒张压标准差(24hDSD)、白天收缩压标准差(dSSD)、夜间收缩压标准差(nSSD)均高于非肥厚组,差异有统计学意义(P<005)。Logistic回归分析显示,24h SBP 与dSSD、nSSD为左室肥厚的独立危险因素(P<005)。结论 老年高血压患者的24h SBP 与dSSD、nSSD是影响左室肥厚的独立危险因素,平稳控制血压对防止左室肥厚的发生有一定影响。  相似文献   
63.
目的:探讨PTEN在喉癌中的表达以及与病理学分级、临床TNM分期和预后等因素的关系。方法:应用组织芯片技术结合免疫组织化学、原位杂交的方法对146例喉鳞状细胞癌、40例癌前期病变以及26例声带息肉患者组织中PTENmRNA以及蛋白的表达,结合临床相关因素进行统计分析。结果:PTEN蛋白在声带息肉中无表达,癌前期病变以及喉癌组织的阳性表达率分别为40.00%、43.15%。在喉癌组织中的表达与喉癌的病理分级以及预后差异有统计学意义,与发生部位、临床分期、淋巴结转移差异无统计学意义。PTEN在癌前期病变及喉癌组织的原位杂交阳性表达率分别为77.50%与59.59%。PTEN在癌前期病变以及喉癌组织的原位杂交阳性表达率高于免疫组织化学的蛋白阳性表达率。结论:组织微阵列是一种高效率的实验方法,具有快速、高精确度、节约资源的特点。PTEN的表达与喉癌的预后有关。  相似文献   
64.
Grape seed is an important natural bioactive product with various health benefits. Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal (GI) tract. The present study investigated the effects of grape seed powder (GSP) on ICC properties and GI motility. GSP depolarized the pacemaker potentials of ICCs in a dose‑dependent manner. Y25130 or SB269970 slightly inhibited GSP‑induced effects. However, Y25130 and SB269970 together completely blocked GSP-induced effects. In the presence of inhibitors of protein kinase C, protein kinase A, or mitogen-activated protein kinase, GSP‑induced ICC depolarization was inhibited. GSP increased the intestinal transit rate in normal mice and in mice with acetic acid-induced GI motility disorder. In addition, the levels of motilin and substance P were elevated after GSP dosing. These results demonstrate that GSP can regulate GI motility, and therefore, it is a potential therapeutic agent for treating GI motility disorders.  相似文献   
65.
目的探讨彩色多普勒超声对锁骨下动脉窃血综合征的诊断价值。方法应用彩色多普勒超声观测颈动脉、颅内外段椎动脉、锁骨下动脉、无名动脉、基底动脉及大脑后动脉的声像图特征及血流动力学的状况。结果锁骨下动脉窃血综合征主要由动脉粥样硬化和多发性大动脉炎所致,且两种原因在年龄组成、性别分布、好发部位上差异有统计学意义。锁骨下动脉窃血综合征患侧血供的代偿主要来自对侧的椎动脉。结论彩色多普勒超声对绝大多数锁骨下动脉窃血综合征可明确诊断。  相似文献   
66.
ObjectivesDespite sufficient hearing gains, many patients with hearing loss have difficulty using hearing aids due to poor word recognition ability. This study was performed to introduce our hearing rehabilitation therapy (HRT) program for hearing aid users and to evaluate its effect on hearing improvement.MethodsIn this prospective randomized case-control study, 37 participants with moderate or moderate-severe sensorineural hearing loss who had used bilateral hearing aids for more than 3 months with sufficient functional hearing gain were enrolled in this study. Nineteen participants were randomly assigned to the control group (CG) and 18 patients were assigned to participate in our HRT program once a week for 8 consecutive weeks (hearing rehabilitation therapy group [HRTG]). Their hearing results and questionnaire scores for hearing handicap and hearing aid outcomes were prospectively collected and compared between the two groups.ResultsAfter completing 8 weeks of the HRT program, the HRTG showed a significantly greater improvement in scores for consonant-only and consonant-vowel sound perception than the CG (P<0.05). In addition, the HRTG showed a significant improvement in hearing ability as measured by two questionnaires (P<0.05), while no differences were observed in the CG. However, word and sentence recognition test results did not show significant differences between the two groups.ConclusionEven after short-term HRT, patients had subjectively better hearing outcomes and improved phoneme perception ability; this provides scientific evidence regarding a possible positive role for HRT programs in hearing aid users. Further validation in a larger population through a long-term follow-up study is needed.  相似文献   
67.
Although silicon dioxide (SiO2), silver (Ag) and iron oxide (Fe2O3) nanoparticles are widely used in diverse applications from food to biomedicine, in vivo toxicities of these nanoparticles exposed via the oral route remain highly controversial. To examine the systemic toxicity of these nanoparticles, well‐dispersed nanoparticles were orally administered to Sprague–Dawley rats daily over a 13‐week period. Based on the results of an acute toxicity and a 14‐day repeated toxicity study, 975.9, 1030.5 and 1000 mg kg–1 were selected as the highest dose of the SiO2, Ag and Fe2O3 nanoparticles, respectively, for the 13‐week repeated oral toxicity study. The SiO2 and Fe2O3 nanoparticles did not induce dose‐related changes in a number of parameters associated with the systemic toxicity up to 975.9 and 1000 mg kg–1, respectively, whereas the Ag nanoparticles resulted in increases in serum alkaline phosphatase and calcium as well as lymphocyte infiltration in liver and kidney, raising the possibility of liver and kidney toxicity induced by the Ag nanoparticles. Compared with the SiO2 and Fe2O3 nanoparticles showing no systemic distribution in all tissues tested, the Ag concentration in sampled blood and organs in the Ag nanoparticle‐treated group significantly increased with a positive and/or dose‐related trend, meaning that the systemic toxicity of the Ag nanoparticles, including liver and kidney toxicity, might be explained by extensive systemic distribution of Ag originating from the Ag nanoparticles. Our current results suggest that further study is required to identify that Ag detected outside the gastrointestinal tract were indeed a nanoparticle form or ionized form. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
68.
Bioassay-guided fractionation of an 80% MeOH extract of leaves and twigs of Juglan sinensis has resulted in the isolation of four new triterpenes (1-4) and 17 known triterpenes (5-21). The new compounds were determined to be 1-oxo-3β,23-dihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (1), 1-oxo-3β-hydroxyolean-18-ene (2), 3β,23-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), and 3β,22α-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (4) by spectroscopic analysis. Compounds 2, 13, 15, and 21 showed antiproliferative activities (14.2, 14.8, 15.6, and 11.0% at 100 μM, respectively) in HSC-T6 cells. Flow cytometry assays revealed that these compounds inhibited HSC-T6 proliferation by inducing apoptosis.  相似文献   
69.
Objective: To compare the chemical characters of Sparganii Rhizoma from different areas via chromatographic analysis and to establish a sensitive LC/MS method for quality assessment of Sparganii Rhizoma.Methods: Under the optimised HPLC-PDA chromatographic conditions,twenty batches of Sparganii Rhizoma were analyzed by HPLC fingerprints.Principal component analysis(PCA),orthogonal projections to latent structures discriminant analysis(OPLS-DA)and hierarchical cluster analysis(HCA)were performed based on all peak areas of Sparganii Rhizoma fingerprints.Meanwhile,part of common peaks were subsequently quantified by UFLC-QTRAP-MS.Results: The similarity values of HPLC fingerprints fluctuated in a wide range of 0.511–0.973,which showed variable differences of chemical characters among Sparganii Rhizoma from twenty habitats.PCA,OPLS-DA and HCA indicated that samples could be divided into five groups with different chemical characters,which generally corresponded with their geographical distributions.A total of 31 peaks in HPLC fingerprints were marked,and eight of them were identified and quantified.The quantitative result was generally in agreement with the classifications based on HPLC fingerprints,which indicated that Sparganii Rhizoma samples from eastern China mostly contained more contents including phenolic acids and flavonoids.Conclusion: This study not only proved that there were relationships between geographic distributions and internal chemical compositions of plants,which could provide evidence to the traditional Chinese medicine concept "geo-authentic",but also supplied a sensitive and rapid simultaneous quantitive method for the quality estimation of Sparganii Rhizoma.  相似文献   
70.
LASIK动物模型建立的分析探讨   总被引:2,自引:0,他引:2  
目的:探讨有效、合理地建立LASIK动物模型的方法。方法:通过对乌拉坦腹腔麻醉与戊巴比妥钠耳缘静脉麻醉、眼球脱臼与外眦切开、手术后睑裂缝合与角膜暴露、鼻侧与上方角膜瓣等不同麻醉方法、不同眼球固定方法、术后角膜状态、不同方位角膜瓣的比较,探讨有效、合理地建立LASIK动物模型的方法。结果:200g/L乌拉坦腹腔麻醉、眼球脱臼、术后角膜暴露、鼻侧角膜瓣等可以有效避免动物意外死亡、眼球吸附不牢固、角膜瓣移位等并发症。结论:200g/L乌拉坦腹腔麻醉、眼球脱臼、术后角膜暴露、鼻侧角膜瓣可以合理地建立LASIK动物模型。  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