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   4126篇
  免费   141篇
  国内免费   83篇
耳鼻咽喉   33篇
儿科学   263篇
妇产科学   117篇
基础医学   228篇
口腔科学   127篇
临床医学   527篇
内科学   583篇
皮肤病学   64篇
神经病学   358篇
特种医学   110篇
外科学   627篇
综合类   380篇
现状与发展   3篇
一般理论   1篇
预防医学   374篇
眼科学   75篇
药学   128篇
  1篇
中国医学   27篇
肿瘤学   324篇
  2024年   4篇
  2023年   103篇
  2022年   125篇
  2021年   196篇
  2020年   177篇
  2019年   117篇
  2018年   142篇
  2017年   107篇
  2016年   130篇
  2015年   111篇
  2014年   276篇
  2013年   293篇
  2012年   165篇
  2011年   193篇
  2010年   132篇
  2009年   166篇
  2008年   169篇
  2007年   152篇
  2006年   142篇
  2005年   156篇
  2004年   118篇
  2003年   101篇
  2002年   89篇
  2001年   90篇
  2000年   75篇
  1999年   77篇
  1998年   73篇
  1997年   57篇
  1996年   56篇
  1995年   53篇
  1994年   44篇
  1993年   42篇
  1992年   42篇
  1991年   39篇
  1990年   35篇
  1989年   34篇
  1988年   34篇
  1987年   30篇
  1986年   34篇
  1985年   33篇
  1984年   26篇
  1983年   11篇
  1982年   18篇
  1981年   19篇
  1980年   15篇
  1979年   10篇
  1978年   7篇
  1977年   8篇
  1976年   9篇
  1975年   10篇
排序方式: 共有4350条查询结果,搜索用时 31 毫秒
51.
本文ELLSA检测,对55例HBV感染者血清中的抗-HBcIgM随访研究其动态变化。结果发现,急性乙肝35例抗-HBcIgM的阳性率在入院时,6个月,12个月分别为100%(35/35),86%(31/36),及34%(6/18),提示抗-HBcIgM在6个月大都保持阳性,至12个月大部分消失;“无症状”携带者20例抗-HBcIgM阳性率在首检时,6个月,24个月都为100%(各为20/20,17/17,及10/10),提示“无症状”携带者的抗-HBcIgM很难自然消失,同时把抗-HBcIgM和HBsAg检测对比,提示HBsAg阴性不能排除急性乙肝的诊断。  相似文献   
52.
目的: 探讨超声引导下标准通道经皮肾镜取石术(percutaneous nephrolithotomy,PCNL)治疗孤立肾肾结石患者的长期有效性和安全性。方法: 回顾性分析2008年9月至2014年6月于北京大学人民医院行PCNL治疗的22例孤立肾肾结石患者临床资料以及5年以上随访资料,记录围手术期相关指标、术后无石率(stone free rate,SFR)及并发症发生率,采用超声检查评估远期结石复发率,通过血肌酐及估计肾小球滤过率(estimated glomerular filtration rate, eGFR)评估肾功能情况。结果: 本组22例患者中,平均年龄为(50.3±11.8)岁,10例解剖性孤立肾,12例功能性孤立肾,中位结石直径为1.65(1.1~3.9) cm,全部为多发结石,包括7例鹿角形结石。术前的中位血肌酐为104.5(60.0~460.0) μmol/L,平均eGFR为(60.3±29.4) mL/min。平均手术时间为(88.2±42.0) min,各有11例单通道和双通道PCNL。术后第一天的中位血肌酐为102.0(63.0~364.0) μmol/L,平均eGFR为(58.0±25.1) mL/min,与术前相比差异均无统计学意义。术后平均住院时间为(8.7±5.2) d。本组有5例(22.7%)患者出现短期并发症,其中4例患者同时出现术后感染和大量出血,保守治疗后好转,1例患者出现胸膜损伤,行胸腔闭式引流后好转; 2例(9.1%)患者出现长期并发症,术后3个月发生输尿管狭窄,行球囊扩张术后好转;其余15例(68.2%)患者均未见并发症。中位随访时间为6.2(4.7~11.1)年,最近一次随访的中位血肌酐为104.0 (72.4~377.0) μmol/L,平均eGFR为(60.1±23.7) mL/min,与术前相比差异均无统计学意义,6例(27.3%)患者出现肾功能减退。术后初始和最终SFR分别为72.7%和100%; 6.2年的随访时间内9例(40.9%)患者结石复发,复发后共进行13次取石手术,最近一次随访的SFR为63.6%。结论: 本研究目前是国内外已有报道中关于孤立肾肾结石患者PCNL术后随访时间最长的研究,超声引导下标准通道PCNL治疗孤立肾肾结石是安全有效的,可以达到理想的SFR。长期随访结果表明仍有较高的结石复发率,但术后患者远期肾功能稳定,部分患者出现轻度肾功能减退。  相似文献   
53.
OBJECTIVE: This prospective study examined the interaction of clinical course of disease and brain structure with time in schizophrenic patients. METHOD: A total of 21 first-episode schizophrenic patients, 10 patients with other psychiatric disorders and a control group of 9 healthy volunteers had CT at first admission and at reinvestigation 5 years later. RESULTS: At first admission all of the patients had enlarged cortical fissures and sulci compared to controls, and the duration of untreated psychosis was significantly correlated with sulcal enlargement. At reinvestigation, frontal and central brain atrophy had progressed in schizophrenic patients. CONCLUSION: The study indicated that ongoing psychosis and lifetime dose of classical antipsychotics were the main candidates accounting for the finding of progressively disturbed brain structure during the first 5 years of schizophrenia.  相似文献   
54.
Background: Higher complication rates and lower success in surgery for severe obesity have been reported for patients with government pay status. We examined the effect of pay status upon outcome in surgical treatment of obesity. Methods: This was an observational study from an aggregate data set of individual patient information. Government pay status (G) was defined as full or partial medical care payment through Medicare, Medicaid, or Veterans Administration. Payment entirely by private insurance was defined as private (P). Operations were classified as either simple (S, gastric restriction) or complex (C, gastric restriction with small bowel bypass). Two measures of outcome, perioperative complication rate and weight loss success (≤50% excess weight), were examined to determine pay status effect. Results: More G than P patients were treated with simple procedures (79% vs 51%, p < 0.05). Perioperative complication rates were more common for G than P patients (14.4% vs 9.1%, p < 0.05). One-year weight loss success was higher for P than G, regardless of operation type. Conclusion: Pay status should be included in characterization of patient groups and in the analysis of results when effectiveness of surgical treatment for severe obesity is reported.  相似文献   
55.
The Prader-Willi syndrome shortens the life of patients due to the morbid obesity which it entails. The compulsive hyperphagia associated with it makes a dietetic treatment or a gastroplasty difficult. This study presents the case-histories of three patients suffering from the Prader-Willi syndrome who were operated on by means of a Scopinaro's bilio-pancreatic diversion. Following a marked reduction the first year, the weight loss stabilized and then tended to diminish. The observation of three cases which continued for two and a half to six years did not reveal any considerable metabolic problems. The deficiency of iron, vitamins D and B12 as well as folic acid had to be made up by supplementation. These results are comparable with the most favorable ones in the literature. Even if the effect on the weight loss is not spectacular, the operation manages to hold off the development of the obesity, inexorable for those with the Prader-Willi syndrome, and prevents lethal complications, without having notable side effects. Lifting coercive dietary measures improves the quality of life.  相似文献   
56.
BACKGROUND: The impact of various medical and demographic factors on the quality of life (QoL) of breast cancer patients has been discussed controversially. We investigated the influence of six different factors on long-term QoL and body image of women with primary breast cancer. PATIENTS AND METHODS: Two-hundred and seventy-four breast cancer patients were administered the QoL questionnaire following a mean interval of 4.2 years after primary diagnosis. All women had been primarily treated for stage I to III breast cancer without evidence of distant metastases. QoL was evaluated by using the QLQ-C30 questionnaire Version 2.0. Supplementary scales included body image, satisfaction with surgical treatment, cosmetic result and fear of recurrence. We analyzed the impact of tumor stage, surgical treatment, adjuvant radiotherapy, adjuvant cytotoxic therapy, age and length of follow-up period on the examined outcome parameters. RESULTS: At the time of the follow-up examination, patients showed minor impairment of QoL (mean 67.8) and body image (mean 24.8), but more fear of recurrence (mean 60.7). None of the studied factors had a significant impact on overall QoL (P >0.05) according to the QLQ-C30 questionnaire. In contrast, with the exception of the factors 'cytotoxic therapy' and 'radiotherapy' all investigated variables influenced at least one of the additional psychological scales (P <0.05). The primary surgical treatment modality had the strongest impact and affected all four scales. Patients treated with breast conservation reported a more favorable body image, compared to those treated with mastectomy (17.2 versus 37.5, P <0.01), more satisfaction with surgical treatment (4.0 versus 10.7, P = 0.01), rated a better cosmetic result (75.5 versus 57.1, P <0.01), but presented more fear of recurrence (63.9 versus 55.3, P = 0.04). CONCLUSION: Current QoL questionnaires do not sufficiently cover all relevant aspects of QoL, but might be complemented by breast cancer specific aspects such as body image and fear.  相似文献   
57.
This study evaluated the outcome of 33 children with asthma-like symptoms without objective evidence of asthma, and the role of certain factors in predicting the development of clinical asthma in these children. Data on symptom histories, lung functions (flow-volume spirometry, free running test and methacholine inhalation challenge test) and atopic sensitization (skin prick tests and markers of eosinophilic inflammation) were collected twice with an interval of 2 y, and the diagnoses were re-evaluated after the follow-up period. Based on the results, it was concluded that one-third of the children with prolonged or recurrent lower airway symptoms, such as cough or wheeze, either have mild asthma or will develop asthma in the near future. Children who had a significant response [≥ 10% fall in forced expiratory volume in 1 s (FEV1)] in the free running test formed a risk group for active asthma, whereas other baseline characteristics seemed not to predict the outcome.  相似文献   
58.
Amadori A, Gentilini P, Bucchi L, Innocenti MP, Falcini F, Martini F, Fabbri M, Liverani M, Danesi S, Piantini B, Milandri C, Saragoni L, Amadori D. A registry-based study of follow-up failures in the screening experience of cervical cancer patients. Int J Gynecol Cancer 1998; 8 : 251–256.
Although all components of cervical screening are at risk of error, most studies of the previous screening experience of cervical cancer patients addressed only the false negative cytology results. Other reports showed the importance of screening failures not attributable to the Pap smear. We studied the relative frequency of all types of error observed in the screening history of 115 cervical cancer cases (median age, 60; range, 23–89) registered with the population-based Romagna Cancer Registry in Forlì (northern Italy) between 1986 and 1993. For each case, a search was made for all cytology, colposcopy, biopsy, and treatment reports issued prior to diagnosis. Eighty-one (70.4%) patients had never had a Pap smear. Eight (7.0%) were diagnosed at their first test. Twenty-six patients (22.6%) had had at least one previous smear. Among these, 10 were screened during the five years prior to diagnosis: three patients had false negative cytology results, one patient did not comply with the recommendation for an early repeat smear, two patients with positive cytology results underwent colposcopy with considerable delay (7 and 9 months), one patient had a negative colposcopy (without biopsy), and three patients had biopsies histologically reported as negative. An overview of the registry-based studies of screening histories reported so far from Italy (total number of cases 262) demonstrated that patients with serious shortcomings in follow-up after smear test, colposcopy, biopsy, clinical assessment, and treatment accounted for a substantial proportion of screening failures.  相似文献   
59.
Objectives: This study was carried out to evolve a method to improve the registration of cancer mortality data in Chennai (Madras, India). Methods: Data on cancer deaths have been collected from the Vital Statistics Department (VSD) by a population-based cancer registry (PBCR) in Chennai only since 1982. The low mortality-to-incidence ratio during 1982-84 suggested under-registration of mortality data. Since 1985, the PBCR has taken special effort to ascertain the vital status of cancer cases by sending reply-paid postcards and/or making house visits. The data on all deaths occurring in Chennai, irrespective of stated cause of death in the death certificate, have been collected from the VSD since 1992. Results: Deaths that occurred in Chennai and obtained by sending reply-paid postcards and/or making house visits were registered in VSD as non-cancer causes of death; hence, these data were not collected from VSD. The sensitivity and positive predictive values of death certificates on cancer diagnosis based on 1992 and 1993 mortality data were 57 percent and 99.5 percent, respectively. Conclusion: Since the accuracy of death certificate information on cancer diagnosis is relatively low in a developing country such as in India, collecting data on all deaths will improve the mortality data registration in PBCRs.  相似文献   
60.
新生儿机械通气后远期肺功能随访   总被引:4,自引:4,他引:4  
目的 了解新生儿机械通气对远期肺功能及反复呼吸道疾病影响。方法 新生儿期用呼吸机治疗16例患儿 ,8年后对其进行随访 ,并作肺功能检测。结果  5 0 %患儿有反复呼吸道疾病症状 ,75 %患儿肺功能异常 ,其中残气量 /肺总量 (RV/TLC)为 5 6 .2 5 %、肺活量 2 5 %时最大呼气流量 (Vmax 2 5 )为 4 3.7%、特殊呼吸道阻力 (sRaw)及特殊呼吸道传导 (sGaw)均为 5 0 %。吸气峰压 (PIP) >2 5cmH2 O组用力肺活量中期平均呼气流速 (FEF 2 5 %~ 75 % )及 5 0 %用力肺活量时的最大呼气流速 (Vmax 5 0 )低于PIP <2 5cmH2 O组。呼气末正压 (PEEP)≤ 4cmH2 O组sRaw >4cmH2 O组。结论 新生儿机械通气可影响远期肺功能。较高PIP或过低PEEP可引起肺损伤 ,从而引起呼吸道阻力增加 ,呼吸道高反应。而儿童期反复呼吸道疾病可能与肺损伤后支气管反应性增高有关  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