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   30475篇
  免费   2871篇
  国内免费   1736篇
耳鼻咽喉   410篇
儿科学   554篇
妇产科学   253篇
基础医学   2729篇
口腔科学   529篇
临床医学   3794篇
内科学   3053篇
皮肤病学   501篇
神经病学   1133篇
特种医学   1028篇
外国民族医学   9篇
外科学   2218篇
综合类   7041篇
现状与发展   3篇
一般理论   2篇
预防医学   3260篇
眼科学   640篇
药学   3661篇
  58篇
中国医学   2445篇
肿瘤学   1761篇
  2024年   98篇
  2023年   367篇
  2022年   1325篇
  2021年   1735篇
  2020年   1362篇
  2019年   841篇
  2018年   906篇
  2017年   1138篇
  2016年   892篇
  2015年   1542篇
  2014年   1912篇
  2013年   2143篇
  2012年   3048篇
  2011年   3134篇
  2010年   2334篇
  2009年   1994篇
  2008年   2091篇
  2007年   1824篇
  2006年   1621篇
  2005年   1322篇
  2004年   891篇
  2003年   669篇
  2002年   484篇
  2001年   395篇
  2000年   333篇
  1999年   166篇
  1998年   73篇
  1997年   58篇
  1996年   38篇
  1995年   41篇
  1994年   42篇
  1993年   19篇
  1992年   40篇
  1991年   43篇
  1990年   21篇
  1989年   19篇
  1988年   14篇
  1987年   11篇
  1986年   9篇
  1985年   12篇
  1983年   6篇
  1982年   6篇
  1979年   5篇
  1978年   4篇
  1976年   4篇
  1974年   4篇
  1972年   4篇
  1971年   5篇
  1969年   4篇
  1968年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
目的 揭示核转录因子(PAX2)在肾小管上皮细胞转分化过程中的可能作用。方法 38例病例组肾组织按间质病变程度分为轻、中、重3组,其中轻度病变15例,中度病变11例,重度病变12例;对照组为5例外伤后肾切除组织。采用免疫组化法评定肾组织PAX2的表达率和肾小管上皮细胞转分化率。对肾间质病变轻、中、重3组组内肾小管上皮细胞转分化率、PAX2表达率作方差分析,对PAX2表达量与肾小管上皮细胞转分化率作相关分析。结果 正常对照组肾小管上皮细胞只表达角蛋白(CK),不表达平滑肌肌动蛋白(α-SMA)及PAX2。病例组肾间质病变轻、中、重3组肾小管上皮细胞均不同程度表达α-SMA及PAX2;不同肾间质病变组,肾小管上皮细胞转分化率及PAX2表达量差异均有统计学意义。相关分析表明,PAX2表达量和肾小管上皮细胞转分化率呈正相关(r=0.886,P〈0.05)。结论 PAX2回归表达可能导致肾小管上皮细胞转分化。  相似文献   
42.
儿童哮喘过敏原检测及临床意义   总被引:16,自引:1,他引:15  
目的 探讨皮肤过敏原点刺试验、血清过敏原检测在儿童哮喘病因诊断、治疗的临床意义。方法 应用粉尘螨及屋尘螨过敏原对121例哮喘患儿及111例对照组儿童进行皮肤点刺试验,其中59例哮喘患儿应用免疫条带印记法进行血清过敏原检测。结果 ①121例哮喘患儿尘螨过敏原皮肤点刺试验总阳性率为28.10%,高于对照组(P〈0.05)。②粉尘螨过敏原阳性33例(27.27%);屋尘螨过敏原阳性32例(26.45%)。③粉尘螨及屋尘螨过敏原皮肤点刺试验结果与哮喘急性发作严重程度有关。④59例哮喘患儿血清过敏原检测阳性46例(77.97%),其中猫毛26例(44.07%)。狗毛23例(38.98%),粉尘螨13例(22.03%),屋尘螨12例(20.34%),海鲜组合10例(16.95%)。⑤皮肤点刺试验与血清过敏原检测的尘螨过敏原检出率,差异无统计学意义。结论 皮肤点刺试验可作为儿童哮喘过敏原检测优先选用的方法。  相似文献   
43.
目的探讨MR扩散加权像在急性病毒性肝炎患者中对肝功能评价的价值。方法健康志愿者20例作为对照组,急性病毒性肝炎(AVH)患者56例(其中肝功能正常组26例,肝功能异常组30例)作为研究组。分别测量各例的表观扩散系数(ADC)并与转氨酶对比分析。结果在扩散敏感系数(b值)取200、400、600 s/mm2时肝功能正常组及异常组的ADC值均高于对照组,差异有统计学意义。肝功能异常组的ADC值与转氨酶呈正相关。结论在急性病毒性肝炎患者中,DWI是一种具有潜力无创的评价肝功能的重要手段,有待于进一步的探索和提高。  相似文献   
44.
Although tacrolimus (TAC) has remarkable effects in ulcerative colitis (UC) patients when given as remission induction therapy, some can develop renal dysfunction during TAC administration, resulting in withdrawal, though related details remain poorly understood. This study was conducted to determine the impact of oral TAC on renal function for remission induction therapy in UC patients. Fifty-five patients (10 elderly, 45 non-elderly) with UC and treated with oral TAC at our hospital were retrospectively evaluated. Renal function was assessed using estimated glomerular filtration rate (eGFR). Although a high clinical response to TAC was seen in both elderly and non-elderly, a decline in eGFR was noted in nearly all patients regardless of age, with a maximum change of −34.4% from the baseline value at week 11. Furthermore, eGFR decline recovered quickly after TAC discontinuation, though did not return to the baseline at two years following cessation. The rate of eGFR change at week 12 was significantly associated with patient age (β = −0.3242, p = 0.0103) and peak serum trough level during TAC treatment (β = 0.3563, p = 0.0051). Furthermore, the rate of decline in eGFR was significantly greater during treatment with TAC in the elderly as compared to non-elderly, with a large difference in eGFR decline rate between those groups also noted at two years after withdrawal of treatment. Careful attention to renal function when administering oral TAC for UC is important and changes in eGFR should be monitored closely in elderly patients even after treatment cessation.  相似文献   
45.
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   
46.
AimWhite matter damage (WMD) is the main cause of cerebral palsy and cognitive impairment in premature infants. Although caffeine has been shown to possess neuroprotective effects in neonatal rats with hypoxic‐ischemic WMD, the mechanisms underlying these protective effects are unclear. Herein, proteins modulated by caffeine in neonatal rats with hypoxic‐ischemic WMD were evaluated.MethodsWe identified differential proteins and performed functional enrichment analyses between the Sham, hypoxic‐ischemic WMD (HI), and HI+caffeine‐treated WMD (Caffeine) groups. Confirmed the changes and effect of proteins in animal models and determined cognitive impairment via water maze experiments.ResultsIn paraventricular tissue, 47 differential proteins were identified between the Sham, HI, and Caffeine groups. Functional enrichment analyses showed that these proteins were related to myelination and axon formation. In particular, the myelin basic protein (MBP), proteolipid protein, myelin‐associated glycoprotein precursor, and sirtiun 2 (SIRT2) levels were reduced in the hypoxic‐ischemic WMD group, and this effect could be prevented by caffeine. Caffeine alleviated the hypoxic‐ischemic WMD‐induced cognitive impairment and improved MBP, synaptophysin, and postsynaptic density protein 95 protein levels after hypoxic‐ischemic WMD by preventing the HI‐induced downregulation of SIRT2; these effects were subsequently attenuated by the SIRT2 inhibitor AK‐7.ConclusionCaffeine may have clinical applications in the management of prophylactic hypoxic‐ischemic WMD; its effects may be mediated by proteins related to myelin development and synapse formation through SIRT2.  相似文献   
47.
48.
Follicular dendritic cell sarcoma (FDCS) of the nasopharynx is a rare malignant tumor that has been described in only a few case reports, and its differential diagnoses include diverse clinicopathologic entities. FDCS is often initially misdiagnosed, especially when examining small biopsy specimens. We herein report a case of FDCS arising in the nasopharynx that was initially misdiagnosed as a nerve sheath tumor. A 44-year-old woman presented with persistent obstruction of the left nasal cavity and underwent an excisional biopsy. The specimen demonstrated morphologic and immunohistochemical features of FDCS. In situ hybridization for Epstein–Barr virus-encoded RNA was negative. The patient was treated with chemotherapy and radiotherapy. The sarcoma recurred near the original site more than 3 years after the initial treatment and was completely resected. At the time of this writing, the patient had remained disease-free for 1 year after resection. This case is being reported to improve the clinical recognition of FDCS.  相似文献   
49.
人牙髓组织缺氧耐受机制的初步研究   总被引:1,自引:0,他引:1  
目的:研究缺氧诱导因子-1α(Hypoxia inducible factor-1α,HIF-1α)和环氧化酶-2(Cyclooxygenase-2,COX-2)在人正常牙髓和炎症牙髓中的免疫定位,探讨缺氧耐受机制在牙髓炎病程中和牙髓自身修复过程中的作用和意义。方法:通过SP法对第1组10例健康牙髓、第2组10例深龋(有过敏症状但无牙髓炎症状)患牙牙髓、第3组15例急性牙髓炎牙髓和第4组15例慢性牙髓炎牙髓进行免疫组化染色,分别对HIF-1α和COX-2进行免疫定位和半定量分析。结果:①HlF-1α在第1组健康牙髓和第2组深龋牙髓标本中,只有个别标本呈弱阳性表达,二组问无显著性差异(P〉0.05),但对比其它二组标本则有显著性差异(P〈0.001):第3组急性牙髓炎牙髓呈强阳性表达,第四组慢性牙髓炎牙髓亦呈阳性染色与第3组比较总体偏弱,有显著性差异(P〈0.05)。②COX-2在第1组牙髓中个别标本呈弱阳性表达;第2组标本绝大多数染色呈弱阳性,与第1组比较有显著性差异(P〈0.05);第3组标本染色均呈强阳性,与前两组比较有显著差异性伊值分别为P〈0.001,P〈0.05);第4组标本亦呈阳性染色,总体上阳性程度明显高于第l组(P〈0.001),高于第2组(P〈0.05),弱于第3组(P〈0.05)。HIF-1α与COX-2的表达关系主要在第3组和第4组牙髓标本中体现明显,在第3组二者的变化大致呈平行关系;在第4组基本呈反向变化关系。结论:HIF-1α和COX-2在牙髓炎病程中可能发挥着重要的生理和病理作用,在牙髓炎进程中和牙髓自身修复过程中可能存在着缺氧环境和缺氧耐受机制。  相似文献   
50.
ACE2基因多态性与原发性高血压的关系   总被引:2,自引:1,他引:1  
目的 研究血管紧张素转化酶2(angiotensin converting enzyme 2,ACE2)基因多态性与广东地区原发性高血压的相关性.方法 高血压组选择门诊与住院的汉族无血缘关系的原发性高血压369例,男194例,女175例;对照组为同期体检的广东地区健康汉族居民199例,男101例,女98例.排除冠心病、高血压、糖尿病、脑血管病及肝功能不良、肾功能不良.按照性别分为两组,采用病例对照的原则,应用聚合酶链反应和限制性内切酶片段长度多态性(polymerase chain reaction and restriction fragment length polymorphism,PCR-RFLP)的方法检测ACE2基因G9570A多态性,并随机抽取20份标本进行基因测序以核实基因分型.在分析各亚组的年龄、体重指数、血压及生化指标的基础上综合分析ACE2基因多态性与原发性高血压的关系.结果 高血压组G等位基因频率:男75.3%,对照组男60.4%,差异有统计学意义(χ2=7.0086,P=0.0081),高血压组,女57.4%,对照组45.4%,差异有统计学意义(χ2=6.9443,P=0.0084);女高血压组GG基因型的频率明显高于对照组(χ2=12.9499,P=0.0015);G等位基因人群发生高血压的风险高于A等位基因人群,男OR:1.9945,95% CI:1.1916~3.3385,P=0.0082;女OR:1.603,95% CI:1.1274~2.2792,P=0.0085.结论 ACE2-G9570A多态性与原发性高血压相关;携带G等位基因的男性和仅仅携带G基因的女性人群发生高血压的危险性相对较大,提示ACE2基因可作为原发性高血压的候选易感基因.  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