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   224973篇
  免费   17147篇
  国内免费   7188篇
耳鼻咽喉   1263篇
儿科学   7662篇
妇产科学   1559篇
基础医学   19749篇
口腔科学   3661篇
临床医学   23773篇
内科学   56114篇
皮肤病学   2740篇
神经病学   26682篇
特种医学   6410篇
外国民族医学   16篇
外科学   16920篇
综合类   30945篇
现状与发展   31篇
一般理论   9篇
预防医学   19033篇
眼科学   2431篇
药学   15718篇
  192篇
中国医学   10572篇
肿瘤学   3828篇
  2024年   686篇
  2023年   4667篇
  2022年   8379篇
  2021年   11885篇
  2020年   11120篇
  2019年   8429篇
  2018年   8368篇
  2017年   8257篇
  2016年   8584篇
  2015年   8267篇
  2014年   16415篇
  2013年   17636篇
  2012年   13120篇
  2011年   14173篇
  2010年   11432篇
  2009年   10916篇
  2008年   10700篇
  2007年   10157篇
  2006年   9025篇
  2005年   7449篇
  2004年   6330篇
  2003年   5447篇
  2002年   4599篇
  2001年   3978篇
  2000年   3311篇
  1999年   2824篇
  1998年   2713篇
  1997年   2391篇
  1996年   2142篇
  1995年   1937篇
  1994年   1788篇
  1993年   1527篇
  1992年   1464篇
  1991年   1299篇
  1990年   1020篇
  1989年   867篇
  1988年   815篇
  1987年   741篇
  1986年   637篇
  1985年   744篇
  1984年   621篇
  1983年   384篇
  1982年   450篇
  1981年   374篇
  1980年   283篇
  1979年   247篇
  1978年   184篇
  1977年   164篇
  1976年   135篇
  1975年   49篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
本实验复制了莱姆病实验家兔模型,对血液生化23项进行了动态观察。结果表明,血液中谷丙转氨酶、γ-谷氨酰转肽酶、乳酸脱氢酶、谷草转氨酶、β-羟丁酸脱氢酶、磷酸肌酸激酶、胆固醇、尿素氮随病情加重而升高。葡萄糖、尿酸、磷随病情加重而减低。  相似文献   
62.
Abstract Perioscan requires a plaque sample to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA) from relatively few anaerobic periodontal pathogens. Periocheck assays the presence of neutral proteases in crevicular fluid. The aim of this study was to compare these test kits with traditional clinical methods of detecting periodontal disease and to monitor the ability of the kits to reflect the response to initial therapy. 19 patients with moderately severe chronic periodontitis were seen before and after a course of oral hygiene and root instrumentation consisting of 4 appointments. Clinical measurements and test assays were collected at 5 diseased sites and 2 healthy sites in each subject. Complete data from 125 sites were available for statistical analysis. At baseline Periocheck had a sensitivity of 88% and a specificity of 61% whereas Perioscan had a sensitivity of 99% and a specificity of 55%, when related to the clinical diagnosis. A composite clinical assessment, based on improvement or deterioration of one whole unit change of the subjective clinical indices and 2mm changes or greater in probing depth or probing attachment level, revealed 75 sites which improved following treatment, whereas 45 sites did not change and 5 sites deteriorated. The probability that the tests agreed with the clinical outcome after treatment, was calculated as 50.4% for Periocheck and 52% for Perioscan. The diagnostic kits did not reliably reflect the clinical assessment of periodontal disease in the cross sectional study, or the outcome following treatment.  相似文献   
63.
Data on 232 members of a single pedigree, descended from two pairs of original parents, were made available to the participants of Genetic Analysis Workshop 8 (GAW8). In addition to information concerning age and sex, measurements for 10 quantitative traits and genotypes at 22 polymorphic marker loci were also provided for a subset of 193 of these family members. © 1993 Wiley-Liss, Inc.  相似文献   
64.
Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.  相似文献   
65.
Amyloid P (AP) component is present in all types of systemic amyloid deposits. Recently, it has been shown to be also present in cerebral amyloid lesions of Alzheimer's disease (AD). In this study, we used immunocytochemical methods to extend these findings at the electron microscope level and characterize the spectrum of AP immunoreactivity in neurofibrillary pathology (NFP) of AD and other neurodegenerative disorders including Down's syndrome (DS), Creutzfeldt-Jakob, Parkinson's, Pick's and diffuse Lewy body diseases and progressive supranuclear palsy. In AD and DS, AP immunoreaction product was evident in all the classical amyloid lesions and NFP in a large sample of all cortical areas examined. The distribution and relative intensity of immunostaining was similar to that of thioflavin S staining in serial sections. In many cases, however, plaques and vessels stained by anti-AP serum were not apparent with thioflavin S. Serial sections immunostained with antiserum to amyloid A, C-reactive protein or to other proteins involved in systemic amyloidoses and the acute phase response showed no evidence of staining in any of the cerebral lesions. Electron microscopy confirmed that AP immunoreactivity was associated with the abnormal filaments characteristic of NFP as well as amyloid fibrils found in plaques and vessels showing congophilic amyloid angiopathy. Plaques of Creutzfeldt-Jakob disease, Pick bodies of Pick's disease, tangles and Lewy bodies in Parkinson's disease and a subpopulation of Lewy bodies in the diffuse Lewy body disease coexistent with AD were also stained. With the exception of vessels in two of the five cases, AP was not detected in age-matched controls. Our observations indicate AP to be a consistent feature of cerebral NFP and amyloid deposits.  相似文献   
66.
Neuropsychiatric disturbances are extremely common in Alzheimer’s disease (AD), and represent integral features of the illness, as well as appropriate targets for therapy. We are interested in designing trials aimed at preventing or delaying the emergence of psychopathology in AD. For symptomatic treatment of agitation, mood stabilizers, particularly sodium valproate, have proved to be beneficial in some patients. Since these effects take several weeks to emerge, we considered that they might be dependent on potentially neuroprotective actions of valproate, such as inhibition of apoptosis and slowing of neurofibrillary tangle formation. In this article we present the rationale for testing the neuroprotective potential of valproate experimentally in mouse models of tauopathy and in a clinical trial of patients with AD who lack psychopathology at baseline. Together, these studies will provide important tests of the hypothesis that valproate, either through inhibition of tau phosphorylation or some other mechanism, is a useful therapeutic agent to modify disease progression in AD.  相似文献   
67.
Summary Aged common marmosets were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 0.5–2.0 mg/kg/week i.p.) for 16 or 24 weeks, observed for a total of 30 weeks and then killed for measurement of biochemical pramaters in basal ganglia. The MPTP treatment induced a marked depletion in dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the caudate nucleus and putamen. In contrast, the concentrations of five neuropeptides: [Met5]-enkephalin, [Leu5]-enkephalin, cholecystokinin, substance P and neurotensin as measured by a combined HPLC/RIA method, remained unaltered in all basal ganglia regions examined. Enkephalin precursor levels, as reflected by cryptic [Met5]-enkephalin content, were increased in the putamen, but not in the caudate nucleus, as a consequence of MPTP administration. Cryptic [Leu5]-enkephalin content remained unchanged in the striatum of MPTP treated marmosets. Overall, these results suggest an increase in striatal [Met5]-enkephalin release following chronic MPTP treatment of aged marmosets. However, the chronic treatment of aged marmosets with MPTP does not reproduce the neuropeptide alterations characteristic of Parkinson's disease.  相似文献   
68.
老年冠心病患者实施健康教育的远期效果分析   总被引:2,自引:0,他引:2  
目的:探讨老年冠心病患者实施健康教育的远期效果。方法:110例老年冠心病患者被随机分为健康教育组(教育组)及对照组,每组各55例。在常规治疗的基础上教育组在住院期间及出院后4年内给予健康教育处方结合口头卫生宣教及科普板报知识等经常性的健康教育活动,而对照组不予健康教育。结果:教育组患者对冠心病知识的了解情况、饮食控制情况、规律服药治疗情况比对照组好(P<0.01),出院后再次住院次数比对照组少(P<0.01)。而情绪及吸烟量控制两组无显著性差异(P>0.05)。结论:对老年冠心病患者实施经常性的健康教育是控制疾病恶化的重要措施。  相似文献   
69.
The aim of this study was to determine whether preoperative physiologic factors can account for and be used to predict the development of postoperative dysphagia after laparoscopic Nissen fundoplication. One hundred sixty-three patients with gastroesophageal reflux disease underwent laparoscopic Nissen fundoplication with a median follow-up of 14 months (range 6 to 81 months). Preoperative dysphagia was present in 37% (60 of 163) and was relieved in all but five patients (92%). Female sex (P = 0.01) and the presence of a stricture (P = 0.02) were the only preoperative variables associated with the presence of preoperative dysphagia. Eight percent (8 of 103) of patients without preoperative dysphagia developed new-onset dysphagia, and of these 63% (5 of 8) had a normal lower esophageal sphincter (LES) (pressure >6 mm Hg; length >2 cm; abdominal length >1 cm). New-onset dysphagia was significantly more common in patients with a normal LES (22% [5 of 23] vs. 4% [3 of 80], P = 001). Patients with a normal LES had almost a sixfold increase in the risk of developing dysphagia as those with an abnormal LES (relative risk = 5.8). Only a preoperative normal LES (P = 0.02) or mean LES pressures (P = 0.04) were positively associated with the development of postoperative dysphagia. The severity of this dysphagia also showed a strong positive trend of increasing with mean preoperative LES pressures (P = 0.07). Finally, preoperative LES pressure significantly correlated with postoperative LES pressure (r = 0.48, P = 0.01) and with mean residual LES (nadir) pressure (r = 0.33, P = 0.05) offering insight into the mechanism of this dysphagia. In conclusion, preoperative LES parameters play a role in the development of dysphagia after laparoscopic Nissen fundoplication. Patients with a normal LES or high mean LES pressures are at increased risk for developing this complication and should be informed of this before laparoscopic Nissen fundoplication. Presented at the Forty-Second Annual Meeting of The Society for Surgery of the Alimentary Tract, Atlanta, Ga., May 20–23, 2001.  相似文献   
70.
胆道镜应用对肝胆胰术式选择的影响   总被引:1,自引:1,他引:0  
目的 探讨分析胆道镜检查在肝胆胰疾患术式选择中的价值。方法 回顾分析1994~2004年收集术中或联合术后应用胆道镜治疗肝胆胰疾患2276例临床资料,进行分析及总结。结果 1966例肝胆管胆石患者胆道残留结石率从34.5%降至9.6%;82例术中胆道镜发现合并胆管狭窄,其中45例肝胆管膜状狭窄者在胆道镜指导下实施了有效扩张治疗;胆总管下段梗阻患者中224例肿瘤依据形态学检查,结合术中扪诊及活检组织学检查得到确诊,并采取了相应的手术方式。结论 胆道镜的应用有利于肝胆胰疾患术式的选择,可使一些较为复杂的胆道手术变得简单易行;对术前未能确诊的病变可以达到明确诊断并指导选择合理的术式。  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