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   79082篇
  免费   6947篇
  国内免费   4589篇
耳鼻咽喉   925篇
儿科学   966篇
妇产科学   787篇
基础医学   9832篇
口腔科学   1380篇
临床医学   8721篇
内科学   11522篇
皮肤病学   1415篇
神经病学   3932篇
特种医学   3898篇
外国民族医学   21篇
外科学   7969篇
综合类   12073篇
现状与发展   28篇
一般理论   7篇
预防医学   5347篇
眼科学   2349篇
药学   8665篇
  67篇
中国医学   3925篇
肿瘤学   6789篇
  2024年   187篇
  2023年   971篇
  2022年   2465篇
  2021年   3436篇
  2020年   2470篇
  2019年   2259篇
  2018年   2451篇
  2017年   2319篇
  2016年   2459篇
  2015年   3690篇
  2014年   4572篇
  2013年   4528篇
  2012年   6628篇
  2011年   7031篇
  2010年   4645篇
  2009年   4004篇
  2008年   4989篇
  2007年   4725篇
  2006年   4445篇
  2005年   3924篇
  2004年   2964篇
  2003年   2965篇
  2002年   2484篇
  2001年   1685篇
  2000年   1402篇
  1999年   1258篇
  1998年   799篇
  1997年   701篇
  1996年   608篇
  1995年   550篇
  1994年   522篇
  1993年   346篇
  1992年   376篇
  1991年   346篇
  1990年   288篇
  1989年   268篇
  1988年   175篇
  1987年   188篇
  1986年   142篇
  1985年   96篇
  1984年   55篇
  1983年   39篇
  1982年   38篇
  1981年   27篇
  1980年   27篇
  1979年   16篇
  1976年   6篇
  1975年   7篇
  1973年   10篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Summary In order to investigate possible effects of smoking and drinking on the metabolism of toluence in occupational settings, 206 toluene-exposed men (mean age: 31.4 years) in shoemaking, painting, or surface-coating workshops together with 246 nonexposed control men (36.8 years) were studied for the time-weighted average intensities of exposure to toluene, hippuric acid concentration in shift-end urine samples, and the two social habits of smoking and drinking. The mean daily consumptions of cigarettes and ethanol were about 20 pieces and 10 g among smokers and drinkers, respectively. The geometric mean toluene concentration among the exposed subjects was about 20 ppm, with a maximum of 521 ppm. Regression analysis after classification of the subjects by smoking and drinking clearly demonstrated that the two social habits, when combined, markedly reduce the hippuric acid level in the urine of workers exposed to was a significant association between smoking and drinking habits, which hindered separate evaluation of the effects of the two habits on toluene metabolism. Comparison of the present results with the findings reported in the literature, however, suggested that the observed effects may be attributable to smoking rather than to drinking habits.  相似文献   
82.
化学中毒与急性缺氧的双因素联合效应的实验研究   总被引:19,自引:5,他引:14  
目的 研究化学中毒与急性缺氧两因素的联合效应。方法 建立常压常氧、常压缺氧和低压缺氧3种模型,以梭曼(Soman)、氰化钠(NaCN)和4-DMAP(4-dimethylaminophenol)为代表,测定大鼠、小鼠、家猫、PC12细胞、兔血红细胞等在3种模型条件下对毒物药物的行为、生化和生理指标变化。结果梭曼单独作用可导致动物协调运动下降、脑等组织含水率增加、脑组织AChE活性降低、MR下调、NE和cAMP含量增加。急性缺氧单独作用也可引起动物协调运动及自主活动的降低、脑等组织含水率的增加、外周血和脑组织AChE活性升高、MR受体上调、NE和cAMP含量增加、4-DMAP药效升高。化学中毒与急性缺氧同时作用,上述变化更加复杂。结论 化学中毒与急性缺氧两种因素同时作用于机体,对机体产生广泛而复杂的损伤作用。此种作用为两因素的联合效应。缺氧引起的机体功能下降对联合效应的增加部分贡献较大。急性缺氧既可使重要的组织成分发生质或量的变化,也会影响某些抗毒剂的作用强度。  相似文献   
83.
84.
目的 观察左肾动脉狭窄肾性高血压大鼠模型心肌和血管中肝细胞生长因子 (HGF)的表达 ,并观察缬沙坦和螺内酯对其表达的影响。方法 选用 6周龄SD大鼠 2 4只 ,制备左肾动脉狭窄肾性高血压模型 ,分为 4组 ,分别为手术组、假手术组、缬沙坦组、螺内酯组。治疗组分别用缬沙坦 3 0mg/kg·d-1、螺内酯 2 0mg/kg·d-1溶于饮水灌胃 ,1次 /d ,连续治疗 17周。用逆转录 聚合酶链反应 (RT PCR)法检测大鼠心肌和血管HGFmRNA水平。结果  17周后 ,缬沙坦组和螺内酯组的心肌HGFmRNA/ β actinmRNA(1.17± 0 .0 8/ 0 .85± 0 .0 8)高于手术组 (0 .5 7± 0 .0 7) (P <0 .0 1) ,但低于假手术组 (1.3 5± 0 .0 9) (P均 <0 .0 1)。两治疗组肠系膜动脉HGFmRNA水平高于手术组 (P <0 .0 1) ,但低于假手术组 (P均 <0 .0 1)。结论 缬沙坦和螺内酯均能使左肾动脉狭窄肾性高血压大鼠心肌和血管中的HGF升高 ,同时伴有心肌和血管重塑的改善 ,说明HGF在左肾动脉狭窄肾性高血压大鼠的靶器官保护中起着重要作用  相似文献   
85.
中西医结合要为妇女生殖健康创新页   总被引:7,自引:1,他引:6  
45年来,复旦大学妇产科医院在中西医结合临床及科研方面取得了可喜的成就.针刺促排卵的研究,通过观察血雌激素和中枢β-内啡肽(β-EP)的关系,提出了针刺通过耗竭中枢β-EP而促排卵的新认识,认为针刺促排卵的主要适应症是青春期月经失调,并将针刺成功地应用于治疗神经性厌食;补肾化痰的俞氏温补方治疗多囊卵巢综合征(polycystic ovary syndrome, PCOS)被证实是通过提高血促卵泡激素(follicle stimulating hormone, FSH)并诱发排卵而起作用;益肾化瘀的天癸方是通过降低患者及动物模型的雄激素和胰岛素,引起以中枢阿片促黑激素皮质素原、神经肽Y和瘦素受体为主的神经-内分泌-代谢网络调节而发挥促排卵和减肥作用,对高胰岛素型PCOS有良效,并在研究中提出了对PCOS分类的新设想;益肾清火的更年春通过提高中枢与周围组织的雌激素受体及其mRNA表达来调节围绝经期妇女的神经-内分泌-免疫-代谢网络而获优越疗效.这些研究表明,疾病是外环境影响下患者生命网络的某些主脉失调所致,而且亚健康状态的妇女具有初步网络失控的现象,中西医结合将为女性生殖医学研究找到捷径,调控生命网络是防病治病的主要思路.  相似文献   
86.
夜来香根茎水提取液局部麻醉作用的研究   总被引:13,自引:4,他引:9  
目的:研究夜来香(CN)根茎水提取液的局部麻醉作用及其作用机制。方法:采用蟾蜍离体坐骨神经动作电位法、豚鼠皮丘法、椎管麻醉法、表面麻醉法。结果:20%的CN水提取液对蟾蜍离体坐骨神经动作电位可完全消失,但较1%的普鲁卡因稍弱。豚鼠皮丘实验表明,20%CN提取液有浸润麻醉作用,其浸润麻醉效果与1%的普鲁卡因相似,而且盐酸肾上腺素可增强其麻醉强度和明显延长局麻作用时间;家兔椎管麻醉实验表明CN提取液有明显的椎管麻醉作用;CN提取液对家兔角膜也有一定的表麻作用,只是作用强度及持续时间比1%的普鲁卡因稍弱或稍短。结论:CN提取液有明显的局部麻醉作用。  相似文献   
87.
原发性肝癌患者肝切除术前、后免疫细胞表型分析   总被引:1,自引:1,他引:0  
目的研究原发性肝癌(PrimaryLiverCarcinoma,PLC)患者肝切除术前、后免疫细胞表型的变化。方法采用直接免疫荧光标记,流量血细胞计数法(FlowCytometry,FCM)检测方法,动态观察120例PLC患者肝切除术前后外周血T淋巴细胞亚群、NK细胞和HLA鄄DR含量变化。结果肝切除术前肝功能Child鄄PughB级、OGTTL型和术前施行肝动脉栓塞化疗患者外周血CD8+T细胞含量明显低于正常人组,CD4+/CD8+比值则较高(P<0郾05)。全部肝癌患者肝切除术前、后CD3+CD4+T细胞和NK细胞(CD3-CD16+CD56+)含量无明显差异。术后第1天、第3天、第7天和第2周外周血淋巴细胞CD3+CD8+含量明显低于肝切除术前和术后第3周(P<0.01);而CD4+/CD8+比值则显著高于肝切除术前和术后第3周(P<0郾01)。结论PLC合并肝硬变肝储备功能不足、术前肝动脉栓塞化疗和肝切除术可导致机体细胞免疫功能低下,PLC患者肝切除术前行肝动脉栓塞化疗的价值有待深入研究。  相似文献   
88.
Objectives: Congenital tracheal stenosis is a rare disease. Various methods for treatment exist but there is still much debate as to the appropriate surgical procedure. We present our surgical experiences of patch tracheoplasty and slide tracheoplasty as viable methods for the treatment of congenital tracheal stenosis. Methods: From 1994 to 2002, 13 patients were diagnosed with congenital tracheal stenosis. Eight patients (7 symptomatic and 1 asymptomatic) had their stenosis corrected, three by means of pericardial patch tracheoplasty, four by slide tracheoplasty, and one by resection and anastomosis. Concomitant operations were performed on six patients to treat congenital cardiovascular disease. Five patients showing no significant symptoms did not undergo tracheal surgery and received only cardiac procedures. A retrospective review of the hospital course, complications, and long-term results was conducted. Results: Among the patch tracheoplasty group, every patient suffered from granulation tissue formation. One patient died of respiratory acidosis and one was hospitalized due to recurrent granulation tissue, which required frequent bronchoscopy. The third patient from this group is free of all symptoms. Among the slide tracheoplasty group, one patient died of anastomosis disruption. The three remaining patients are alive and well. The one patient who received resection and anastomosis is alive without symptoms. Conclusions: Surgical repair of long-segment congenital tracheal stenosis exhibited high mortality and morbidity rates. Every patient that underwent pericardial patch tracheoplasty suffered from troublesome granulation tissue. As slide tracheoplasty provided relatively good results in the short and mid-term follow-up periods, it seems to be a preferred method for the treatment of long-segment congenital tracheal stenosis.  相似文献   
89.
Objective To study the protective effects of adenovirus-mediated human beta-nerve growth factor gene (hNGFβ) transfer combined with iron fortified nutrition on blast hearing damage in guinea pigs. Methods Deafness was induced by blast (172dB SPL) in 35 healthy guinea pigs. Seven days after noise exposure, 10 guinea pigs were inoculated with adenovirus-mediated hNGFβ (Ad-hNGFβ) into the perilymphatic space (the gene group), another 10 guinea pigs were given hNGFβ combined with iron fortified nutritional diet (the combination group), still another 10 guinea pigs were inoculated with artificial perilymphatic fluid (APF), and 5 guinea pigs served as control, given neither medicine nor noise exposure. Auditory brainstem response (ABR) threshold shifts were monitored in the guinea pigs before blast exposure and after gene transfer. Changes in cochlear morphology were examined with immunohistochemical and HE staining. Results One week after successful inoculation of hNGFβ, it was noted that Ad-hNGFβ protein was expressed in each turn of the cochlea, and its intensity was almost equal. After gene transfer in the combination group and the gene group, ABR threshold shifts at week 1 and 4 were significantly smaller than those of the APF group. HE staining showed that the number of the spiral ganglion cells in the combination group and the Ad-hNGFβ group was significantly higher than that of the control group after 4 weeks (P<0.01). Conclusions Ad-hNGFβ combined with iron fortified nutritional diet was effective in the prevention and treatment of blast hearing damage of cochlear hair cells.  相似文献   
90.
Background: Elder patients with acute coronary syndromes (ACS) are less likely to receive cardiac catheterization. The reasons for this are unclear.
Objectives: To assess whether elder patients who had a documented history of dementia, lived in extended care facilities, or had do not intubate–do not resuscitate (DNR-DNI) advance directives were less likely to receive cardiac catheterization, despite having ACS with high-risk features.
Methods: This was a medical record review conducted at an urban teaching hospital. DNR-DNI status before hospitalization, extended care facility (nursing home or assisted living) residence, and a previous diagnosis of dementia were obtained from the medical record. Patients 65 years and older who presented to the emergency department with acute myocardial infarction or with unstable angina with ST segment deviation were included. Univariate and multivariate logistic regression were performed, and odds ratios (ORs) were reported with their 95% confidence intervals (CIs).
Results: Of the 201 eligible patients, 66 (32.8%) patients did not undergo cardiac catheterization. In the univariate analysis, patients who had dementia, resided in extended care facilities, or were DNR-DNI were less likely to receive cardiac catheterization. Only extended care facility residence (OR, 0.18; 95% CI = 0.04 to 0.83) and DNR-DNI status (OR, 0.19; 95% CI = 0.04 to 0.92) remained significantly associated with decreased cardiac catheterization in the multivariate analysis.
Conclusions: Elder patients with ACS residing in extended care facilities or who are DNR-DNI are less likely to receive cardiac catheterization. Future studies concerning the quality of ACS care for elders should take these variables into account.  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