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   6012篇
  免费   429篇
  国内免费   112篇
耳鼻咽喉   32篇
儿科学   41篇
妇产科学   35篇
基础医学   653篇
口腔科学   639篇
临床医学   471篇
内科学   563篇
皮肤病学   163篇
神经病学   262篇
特种医学   687篇
外国民族医学   1篇
外科学   629篇
综合类   1048篇
一般理论   2篇
预防医学   777篇
眼科学   115篇
药学   154篇
  12篇
中国医学   83篇
肿瘤学   186篇
  2024年   22篇
  2023年   208篇
  2022年   157篇
  2021年   392篇
  2020年   332篇
  2019年   228篇
  2018年   225篇
  2017年   198篇
  2016年   176篇
  2015年   223篇
  2014年   335篇
  2013年   393篇
  2012年   382篇
  2011年   425篇
  2010年   304篇
  2009年   325篇
  2008年   339篇
  2007年   295篇
  2006年   264篇
  2005年   228篇
  2004年   189篇
  2003年   118篇
  2002年   120篇
  2001年   85篇
  2000年   79篇
  1999年   49篇
  1998年   51篇
  1997年   58篇
  1996年   37篇
  1995年   53篇
  1994年   31篇
  1993年   19篇
  1992年   27篇
  1991年   27篇
  1990年   22篇
  1989年   11篇
  1988年   20篇
  1987年   11篇
  1986年   8篇
  1985年   21篇
  1984年   16篇
  1983年   7篇
  1982年   5篇
  1981年   9篇
  1980年   6篇
  1979年   3篇
  1978年   5篇
  1976年   3篇
  1973年   4篇
  1971年   2篇
排序方式: 共有6553条查询结果,搜索用时 15 毫秒
21.
108例支气管哮喘患者舌脉象特征分析   总被引:1,自引:0,他引:1  
目的:探讨对支气管哮喘临床辨证有意义的舌脉象客观指标,以辅助临床诊断。方法:应用TP—I型中医舌脉象数字化分析仪检测108例患者舌脉象参数,分析支气管哮喘发作期与缓解期的舌脉象特征。结果:108例支气管哮喘患者的舌象中,舌色以淡红舌、淡紫舌多见,舌苔以白苔、黄苔、薄苔为多见;脉象以弦脉、滑脉、弦滑脉为多见;舌脉象参数中舌色指数、苔色指数、厚苔指数、胖瘦指数在哮喘发作期各证型中有显著性差异(P〈0.05);RPSR1、RPSR3、RPSR4、RBF、RLMS2、PLMP2、RLMS3、RLMP3在哮喘发作期与缓解期有显著性差异(P〈0.05)。结论:支气管哮喘患者的脉象参数、舌色指数、苔色指数、厚苔指数、胖瘦指数、RPSR1、RPSR3、RPSR4、RBF、RLMS2、PLMP2、RLMS3、RLMP3对其辨证分型有重要参考价值。  相似文献   
22.
By digital subtraction angiography(DSA), the authors made observations on 108 normal ophthalmic arteries in 80 patients with regard to the origins, courses, branching, morphology and anastomoses of the vessels. The merits and demerits of DSA in observing the ophthalmic artery were discussed. Eye Science 1994; 10: 157- 162.  相似文献   
23.
数字减影子宫输卵管造影术   总被引:3,自引:0,他引:3  
目的:介绍和评价数字减影与自动高压注射器联合应用于子宫输卵管造影(HSG)。方法:自行设计造影用硅胶管使之能与自动高压注射器相联接,用40%泛影葡胺和数字减影方法作造影;随机抽取常规透视点片碘油造影片44份,数字减影泛影葡胺造影片50份进行对照分析。结果:两组比较:清晰度宫腔无显著性差异(P>0.05),输卵管有显著性差异(P<0.05);输卵管通畅率、血管或(和)淋巴管回流率有显著性差异(P<0.05)。盆腔涂布无显著性差异(P>0.05)。结论:采用数字减影与高压注射器行子宫输卵管造影能提高造影质量。  相似文献   
24.
Hyperexcitability of the motor system has been reported in Parkinson's disease (PD). We evaluate how cutaneous afferents modulate motor excitability in PD patients and whether abnormal modulation is correlated to parkinsonian symptoms. Digital stimulation causes abnormal enhancement of motor responses in patients. This effect may be one of the features of motor hyperexcitability in PD. Cutaneomotor hyperexcitability correlates with clinical scores, suggesting that abnormal processing of cutaneous inputs might contribute to the pathogenesis of parkinsonian symptoms.  相似文献   
25.
Objective: We examined the relationship between tolerance development, counterregulatory responses and arterial vasodilating effects evaluated by digital pulse plethysmography. Methods: Twenty patients with stable angina pectoris were exercise tested before, after 2 and after 24 h of open nitrate patch treatment. Results: The effects observed after 2 h of treatment on exercise duration, ST-segment depression, blood pressure and heart rate were lost in most individuals after 24 h. In contrast, the effects on the arterial pulse curves persisted after 24 h, with a mean change from baseline of 29%, compared to 33% at 2 h. After 24 h, a significant decrease in haematocrit and an increase in body weight were observed. The haematocrit changes correlated with the loss of clinical efficacy (r =0.57 for ST-segment depression, and r =0.54 for exercise duration). Conclusion: Clinical nitrate tolerance may be observed despite maintenance of the arterial vasodilating effects, and tolerance is more related to plasma volume expansion as a counterregulatory mechanism. Received: 28 February 1996/Accepted in revised form: 5 July 1996  相似文献   
26.
目的 探讨肺癌侵犯中央肺动脉继发肺低灌注的CT特征及其诊断价值。方法 对2 0例手术及病理证实的肺癌侵犯中央肺动脉 (cancerousinvasionofcentralpulmonaryarteriesinlungcancer,CICPA)患者术前肺血管DSA及增强螺旋CT(含高分辨率CT ,即HRCT)征象行前瞻性对照研究。根据DSA和CT胸膜下末梢肺动脉分布和数量变化 ,即肺血管征、肺毛细血管充盈度和肺实质强化后密度及时间 密度曲线变化 (即肺实质征 ) ,行两者间的盲法对照 ,统计学分析CT与DSA征象及其一致性 ,评估CT对CICPA继发肺低灌注的诊断价值。结果  2 0例手术病理证实的CICPA病例中 ,共3 0支肺叶动脉受累 ,DSA显示 90 % (2 7/3 0 )出现肺叶低灌注征象 ,CT诊断肺低灌注敏感度为 78%(2 1/2 7) ,特异度 10 0 % (3 /3 ) ,准确度 80 % (2 4/3 0 )。肺低灌注与CPA狭窄程度无明显相关性 (rs=0 40 ,P =0 0 73 )。CT与DSA的肺血管征一致性较好 (Kappa =0 69,P <0 0 0 1) ,而肺实质征一致性稍差 (Kappa =0 3 7,P =0 0 11)。结论 肺低灌注是肺癌侵犯中央肺动脉的常见表现 ,CT对其定性诊断具有重要价值 ,而定量判断有一定限度  相似文献   
27.
目的 :评价平板式全数字心血管造影机在周围血管及非血管介入中的应用价值。方法 :对平板探测器(FPDD)X线成像与影像增强器 电视 (IITV)X线成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标的检测及比较。随机选择上述两机型在周围血管及非血管介入诊疗病例图像资料各 6 0例 ,由三名高年资医师对其图像质量进行综合评价 ,记录评价结果 ,并进行比较。结果 :FPDD成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标均优于IITV成像 ;在人体各部位周围血管及非血管介入诊疗中的图像综合评价结果也优于IITV成像。结论 :平板式全数字化心血管造影机不仅适用于心血管介入 ,同时能满足全身各部位周围血管及非血管介入诊疗的需要。  相似文献   
28.
BACKGROUND: Recent hospital and cancer registry data show increasing prostate cancer incidence in Nigeria, which was previously regarded as a low incidence region. This study investigates the prevalence of prostate cancer risk in a previously unscreened cohort of rural Nigerians. METHODS: Rural Nigerian men, 40 years and older, were screened by serum prostate-specific antigen (PSA) and digital rectal examination (DRE) and those with PSA >/= 4 ng/mL and/or abnormal DRE were referred for prostate biopsy. RESULTS: Of 200 consecutive men invited, 151 (75.5%) presented for screening, the mean age was 56.45 + 15.1 and 95 (61.6%) were >/= 50 years of age. Of the 140 who consented to a blood test, PSA correlated with age (r = 0.3, P < 0.01), 14 (10.0%) had abnormal PSA >/= 4 ng/mL, increasing from 3 (3.6%) in men < 60 years to 4 (50%) in men >/= 80 years. The rate was 13 (15.7%) for men >/= 50 years and there was no evidence of increased incidence of prostatitis in the community. Mean (median) PSA in ng/mL increased from 1.17 (0.60) in the youngest to 13.75 (4.45) in the oldest cohort. Of those who accepted DRE, 38 (29.0%) had an enlarged prostate, including two who had nodular prostate, one-third with symptoms, increasing from 4 (5.4%) in those < 50 years to 6 (75.0%) in men >/= 80 years. The proportion of men with PSA >/= 4 ng/mL among those with enlarged vs normal prostate is 27.0 to 3.4%, P < 0.001, and the pattern was similar for men >/= 60 years and those < 60 years of age. The 40 (32.0%) men referred for prostate biopsy defaulted mainly because they did not fully understand the need for further investigation because they were symptom free or afraid of the possible side-effects of the procedure or diagnosis of cancer. CONCLUSION: The proportion of men with PSA >/= 4 ng/mL is comparable to that of previously unscreened populations with high incidence of prostate cancer such as African-American men. A larger study is required to confirm these findings and intensify efforts to determine the prostate cancer detection rate by biopsy in this population. A prostate cancer awareness and education campaign will be useful in this community.  相似文献   
29.
The state of “nodding off” which the psychoanalyst may experience during therapy is a phenomenon that requires further investigation into its nature, causes, and effects. Even if it occurs only sporadically and is a physiological necessity, it nevertheless has a certain effect and can present certain advantages. This introduction of resistance in the form of sleep can sometimes provide an opportunity in the development of sensorimotor functions for the patient to verbalize his experience, and in any case this phenomenon should not be taken lightly. Recourse to current knowledge regarding sleep can improve our understanding of this phenomenon, and we should be prepared to take the risk of examining psychoanalysis on the basis of a non-analytical approach, i.e. primarily psychobiological and cognitive. This also permits a link to be made between the psychoanalyst’s therapeutic activity and the contextual phenomena which influence cerebral activity and its level of vigilance which is expressed by specific types of verbalization. The pertinence of this risk-taking should also be examined, and a distinction made between physiologically necessary somnolence and other causes. It appears that in the present context, the induction of a state of somnolence is caused by the narcissistic characteristics of a transferential relation that is in the process of development; that is to say, the “positive aspects’’ of narcissism, which are an integral part of psychic growth. However, we should also bear in mind that these narcissistic characteristics can also be expressed in the form of resistance.  相似文献   
30.
目的 与多层面螺旋CT三维血管造影 (MS 3D CTA)和DSA比较 ,探讨三维时间飞跃法MR血管造影 (threedimensionaltimeofflightMRA ,3DTOFMRA)图像后处理血液铸型技术 (fly around)诊断颈内动脉系颅内动脉瘤的优势和临床应用价值。方法  18名疑诊颈内动脉系颅内动脉瘤病人 ,男 4例 ,女 14例 ;年龄 17~ 76岁 ,平均 4 9 8岁 ;其中蛛网膜下腔出血 (SAH) 14例、动眼神经麻痹 4例。所有病人均接受 3DTOFMRA和MS 3D CTA检查 ,17名接受DSA检查 ,确诊后均经手术治疗。 3DTOFMRA用Toshiba 1 5T超导型MR系统VISART的 3D TOF序列采集原始数据。其参数为 :TR 30ms,TE 6 8ms ,反转角 2 0° ,视野 (FOV) 17cm× 19cm ,矩阵 16 0× 2 5 6 ,采集层块厚度 5 0~ 6 0mm ,层厚 1 2mm ;原始图像后处理方法采用最大密度投影 (MIP)和血液铸型。MS 3D CTA用Toshiba多层螺旋CT Aquilion采集原始数据。其参数为 :扫描速度 0 5s/r,层厚 1 0mm ,螺距 3 5 ;用高压注射器静脉注射非离子型对比剂 ,注射剂量 2 0ml/kg体重 ,注射流率 4 0~ 5 0ml/s ,延迟时间 15~ 18s ;原始图像后处理方法同 3DTOFMRA。图像后处理工作站均用SGIO2 ,后处理软件为Alatoview ,版本 1 4 2。DSA用SiemensMulti StartOT经股动脉插管行常规脑动脉四血管造影  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