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   79426篇
  免费   6897篇
  国内免费   4560篇
耳鼻咽喉   925篇
儿科学   984篇
妇产科学   788篇
基础医学   9859篇
口腔科学   1380篇
临床医学   8717篇
内科学   11570篇
皮肤病学   1419篇
神经病学   3936篇
特种医学   3968篇
外国民族医学   21篇
外科学   7992篇
综合类   12101篇
现状与发展   28篇
一般理论   7篇
预防医学   5358篇
眼科学   2349篇
药学   8685篇
  67篇
中国医学   3925篇
肿瘤学   6804篇
  2024年   189篇
  2023年   972篇
  2022年   2470篇
  2021年   3445篇
  2020年   2471篇
  2019年   2262篇
  2018年   2450篇
  2017年   2320篇
  2016年   2460篇
  2015年   3690篇
  2014年   4578篇
  2013年   4528篇
  2012年   6636篇
  2011年   7041篇
  2010年   4654篇
  2009年   4009篇
  2008年   5005篇
  2007年   4712篇
  2006年   4455篇
  2005年   3926篇
  2004年   2976篇
  2003年   2971篇
  2002年   2473篇
  2001年   1679篇
  2000年   1402篇
  1999年   1260篇
  1998年   821篇
  1997年   722篇
  1996年   619篇
  1995年   553篇
  1994年   536篇
  1993年   360篇
  1992年   385篇
  1991年   352篇
  1990年   301篇
  1989年   278篇
  1988年   190篇
  1987年   195篇
  1986年   150篇
  1985年   103篇
  1984年   58篇
  1983年   42篇
  1982年   44篇
  1981年   33篇
  1980年   33篇
  1979年   17篇
  1978年   7篇
  1975年   8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
41.
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   
42.
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   
43.
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   
44.
目的:探讨鼻息肉病的可行性手术方法,以提高治疗效果。方法:21例鼻息肉病患者一侧行唇龈沟径路,保留下鼻甲的改良内侧上颌骨切除术(modifiedmedialmaxillectomy,MMM);另侧行单纯鼻息肉摘除和鼻内筛窦切除术,并作为对照组。结果:术后随访12~34个月,平均20个月;改良内侧上颌骨切除术侧未见复发,另侧复发6例,两组复发率差异有显著性(P<0.05)。结论:改良内侧上颌骨切除术使鼻息肉病患者术后复发率显著降低,治疗效果显著,是一种可供选择的有效的治疗手段。  相似文献   
45.
尿毒症患者的性激素变化及其临床意义探讨   总被引:6,自引:0,他引:6  
目的 :探讨女性尿毒症患者卵巢功能障碍的发病情况及其临床意义。方法 :应用酶免疫法 (EIA)测定了2 3例更年期前女性尿毒症非透析患者、15例透析患者及 2 9例健康献血者中促卵泡素 (FSH)、泌乳素 (PRL)、促黄体素 (LH)、雌二醇 (E2 )及孕酮 (P)的水平。结果 :尿毒症女患者PRL、FSH及LH均较健康对照组升高 ,而孕酮值显著降低 ,对此均有显著差异 ;且尿毒症女患者PRL升高、孕酮值降低与肾小球滤过率 (GFR)呈明显相关。透析患者较非透析患者PRL升高更为明显 ,孕酮值亦较非透析患者有所升高 ,但无显著意义。结论 :尿毒症女患者的排卵障碍及月经紊乱等都与尿毒症的严重程度相平行。透析并不能改善尿毒症女患者的卵巢功能障碍 ,只有纠正与改善肾功能 ,才能使尿毒症女患者的卵巢功能得以改善  相似文献   
46.
为探讨临床中使用钙制剂抢救链霉素过敏休克病人有良好效果的原因,由被动血凝试验、被动皮肤过敏试验和ELISA法证实,Ca~( )可以抑制链霉素抗原-抗体的反应。这种抑制作用是通过Ca~( )链霉素抗原结合,封闭链霉素抗原决定簇来加以实现的。  相似文献   
47.
The purpose of this study was to investigate whether (18)F-FDG PET/CT is useful for localizing dystonic cervical muscles in patients with idiopathic cervical dystonia (ICD) by comparing disease severity before and disease severity after botulinum toxin (BT) injection into hypermetabolic muscles. METHODS: Six patients with ICD underwent (18)F-FDG PET/CT. Dystonic muscles suitable for BT injection therapy were defined as those showing diffusely increased (18)F-FDG uptake. RESULTS: Hypermetabolic cervical muscles were identified in all 6 patients. In 2 patients who underwent PET/CT both in a supine position and in a sitting position during (18)F-FDG uptake, abnormal hypermetabolic muscles were observed by PET/CT only when patients were in the sitting position with their heads and necks in the adopted abnormal involuntary posture. Symptoms were significantly improved in 4 patients who underwent BT injection therapy guided by PET/CT and who were clinically monitored. CONCLUSION: (18)F-FDG PET/CT is potentially useful for identifying dystonic cervical muscles for BT therapy in patients with ICD.  相似文献   
48.
1 宋代社会经济、医事制度与历史地理 1.1 宋代的社会经济 宋朝是我国历史上继唐朝之后,社会经济发展、科技文化进步的一个历史时期,后世有"治隆唐宋"之说.公元960年陈桥兵变,赵匡胤(宋太祖)"黄袍加身"以后,遂代周而自立,是为宋朝,史称北宋.当时的社会在经历了五代十国的战乱之后而趋于安定,经济逐渐恢复,科学也日益发达.  相似文献   
49.
Chymase is known to generate angiotensin II in the vascular wall. In this study we investigated a novel role for chymase other than angiotensin II production in vascular proliferation after balloon injury. Chymase promoted the migration of vascular smooth muscle cells in the matrix-coated invasion chambers and activated promatrix metalloproteinase-2 obtained from the culture medium of vascular smooth muscle cells. Two weeks after balloon injury, significant neointimal formation was found in dog carotid arteries. After injury, active matrix metalloproteinase-2 was increased in parallel with the augmentation of chymase activity that was seen in the proliferating region of the vascular wall. The oral administration of NK3201 (1 mg/kg per day), a chymase inhibitor, prevented neointimal formation and significantly suppressed both active matrix metalloproteinase-2 and chymase activities 2 weeks after injury. These results suggest that chymase inhibitors can prevent the development of intimal hyperplasia via the inhibition of matrix metalloproteinase-2 activation in balloon-injured arteries.  相似文献   
50.
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