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   245956篇
  免费   31741篇
  国内免费   8222篇
耳鼻咽喉   1852篇
儿科学   3111篇
妇产科学   5544篇
基础医学   19151篇
口腔科学   2535篇
临床医学   20747篇
内科学   26655篇
皮肤病学   1563篇
神经病学   1850篇
特种医学   7857篇
外国民族医学   288篇
外科学   33118篇
综合类   33887篇
现状与发展   41篇
一般理论   3篇
预防医学   12829篇
眼科学   430篇
药学   17859篇
  165篇
中国医学   6765篇
肿瘤学   89669篇
  2024年   641篇
  2023年   4937篇
  2022年   9259篇
  2021年   13179篇
  2020年   12221篇
  2019年   10989篇
  2018年   10544篇
  2017年   10990篇
  2016年   11887篇
  2015年   13393篇
  2014年   19796篇
  2013年   19606篇
  2012年   15930篇
  2011年   16325篇
  2010年   12087篇
  2009年   12214篇
  2008年   12378篇
  2007年   11896篇
  2006年   10431篇
  2005年   8649篇
  2004年   7168篇
  2003年   5899篇
  2002年   4961篇
  2001年   4503篇
  2000年   3768篇
  1999年   3190篇
  1998年   2689篇
  1997年   2405篇
  1996年   2002篇
  1995年   1807篇
  1994年   1534篇
  1993年   1197篇
  1992年   1076篇
  1991年   959篇
  1990年   761篇
  1989年   684篇
  1988年   607篇
  1987年   511篇
  1986年   409篇
  1985年   482篇
  1984年   393篇
  1983年   261篇
  1982年   278篇
  1981年   240篇
  1980年   232篇
  1979年   165篇
  1978年   109篇
  1977年   85篇
  1976年   67篇
  1975年   52篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
目的调查70岁以上老年军人慢性阻塞性疾病(COPD)患者的生活质量、病情严重程度及预防治疗情况现状。方法采用问卷调查、体格检查、实验室检查及肺功能检查相结合的方法,对定居成都市军队干休所师以上、70岁以上离休干部以往确诊为COPD、目前仍存活的330例患者进行群体调查,对已经死亡的81例进行回顾性分析。结果COPD发病率为18.9%,平均病程15年,发病年龄大多集中在50~69岁,均有吸烟史,88.8%的患者并有其他基础疾病。生活质量比较差的78例(23.6%),生活质量极差的9例(2.7%)。COPD分级,Ⅰ级(轻度)65例(19.7%),Ⅱ级(中度)166例(50.3%),Ⅲ级(重度)99例(30%)。需长期药物及家庭氧疗的39例(11.8%),需长期住院的9例(2.7%)。结论成都市70岁以上的军队离休干部的COPD发病率高于一般老年人群,吸烟是COPD的最危险因素,COPD仍然是严重影响老年人生活质量的主要疾病,注重缓解期的防治是减少反复发作、提高生活质量、保护肺功能的重要措施。  相似文献   
982.
用多次酶消化法体外培养的大鼠成骨细胞及其鉴定   总被引:4,自引:0,他引:4  
目的 针对目前体外培养成骨细胞方法的不足,建立一种理想的原代培养成骨细胞的方法,为骨替代材料的研究提供成骨细胞.方法 本实验用新生1~2天大鼠颅盖骨,采用多次酶消化法进行细胞体外培养.倒置显微镜观察细胞形态,并对其碱性磷酸酶(ALP)活性及矿化能力进行鉴定.结果 所培养细胞具有成骨细胞的形态学特征及体内成骨细胞的生物学行为.结论 本实验体外培养成骨细胞的方法切实可行,可为骨替代材料的研究提供种子细胞,也可为骨细胞生物学和骨组织工程的研究提供一种客观而有效的实验手段.  相似文献   
983.
目的探讨急性梗阻性结直肠癌的外科处理方法。方法回顾分析1996—2004年收治的58例结直肠癌并发急性肠梗阻患者的治疗方法。全组58例,一期切除吻合26例,一期切除+近端结肠造瘘21例,单纯结肠造瘘5例,捷径手术6例。结果住院期间死亡6例,吻合口漏1例,51例恢复顺利,康复出院。结论重视围手术期的处理,根据急性梗阻性结直肠癌患者的全身情况和局部条件合理选择手术方式。  相似文献   
984.
Community-acquired viral respiratory tract infections (RTI) in lung transplant recipients may have a high rate of progression to pneumonia and can be a trigger for immunologically mediated detrimental effects on lung function. A cohort of 100 patients was enrolled from 2001 to 2003 in which 50 patients had clinically diagnosed viral RTI and 50 were asymptomatic. All patients had nasopharyngeal and throat swabs taken for respiratory virus antigen detection, culture and RT-PCR. All patients had pulmonary function tests at regular intervals for 12 months. Rates of rejection, decline in forced expiratory volume (L) in 1 s (FEV-1) and bacterial and fungal superinfection were compared at the 3-month primary endpoint. In the 50 patients with RTI, a microbial etiology was identified in 33 of 50 (66%) and included rhinovirus (9), coronavirus (8), RSV (6), influenza A (5), parainfluenza (4) and human metapneumovirus (1). During the 3-month primary endpoint, 8 of 50 (16%) RTI patients had acute rejection versus 0 of 50 non-RTI patients (p=0.006). The number of patients experiencing a 20% or more decline in FEV-1 by 3 months was 9 of 50 (18%) RTI versus 0 of 50 non-RTI (0%) (p=0.003). In six of these nine patients, the decline in FEV-1 was sustained over a 1-year period consistent with bronchiolitis obliterans syndrome (BOS). Community-acquired respiratory viruses may be associated with the development of acute rejection and BOS.  相似文献   
985.
986.
We present a case of lung cancer that showed false positive accumulation in an 18F fluorodeoxyglucose positron emission tomography (FDG-PET) scan following induction chemotherapy for suspected metastasis and progression of malignancy. A 66-year-old man was diagnosed with squamous cell carcinoma in the lung, classified as clinical stage IIIA (T2N2M0), and underwent induction chemotherapy. An FDG-PET scan prior to chemotherapy demonstrated accumulation only in the tumor, whereas following treatment it revealed a strong accumulation not only in the tumor, but also in the supraclavicular lymph nodes, which indicated lymph node metastasis. The patient underwent a biopsy of the right supraclavicular lymph node and mediastinoscopy, after which all dissected lymph nodes showed sarcoid reactions and no tumor cells were found pathologically. We concluded that when evaluating the effect of induction chemotherapy for malignancy, a sarcoid reaction might lead to the false positive accumulation of FDG.  相似文献   
987.
The incidence, predictors and clinical significance of acute renal failure (ARF) after lung transplantation are not well described. We retrospectively collected data on 296 patients transplanted at our center between April 1992 and December 2000; follow-up was extended until December 2002. Patients were initially divided into two groups: ARF (doubling of baseline creatinine within 2 weeks after surgery) and NoARF. The ARF group was subdivided into ARFD (dialyzed) and ARFnD (not dialyzed). The incidence of ARF was 56% (166/296), but most cases were ARFnD (n = 143). Independent predictors of ARFD (n = 23) were: baseline GFR (OR 0.98, CI 0.96-0.99, p = 0.012), pulmonary diagnosis other than COPD (OR 6.80, CI 1.5-30.89, p = 0.013), mechanical ventilation > 1 d (OR 6.16, CI 1.70-22.24, p = 0.006) and parenteral amphotericin B use (OR 3.04, CI 1.03-8.98, p = 0.045). Both ARFnD and ARFD were associated with longer duration of mechanical ventilation, increased hospital stay and increased early mortality. One-year patient survival was 92.3%, 81.8% and 21.7% in the NoARF, ARFnD and ARFD groups, respectively (p < 0.0001). After controlling for important covariates, ARFD remained associated with an increased hazard of dying (HR 6.77, CI 4.00-11.44, p < 0.0001). In conclusion, ARF occurs commonly after lung transplantation and affects important clinical outcomes, especially when dialysis is required.  相似文献   
988.
目的:为探讨早期尘肺病患者肺功能评定及其劳动能力鉴定中的应用。方法:本文做了Ⅰ期77例尘肺病人通过临床表现即呼吸困难的判定、高仟伏X线胸片检查、肺功能测定等检查进行了肺功能损伤分级及劳动能力鉴定。结果:矽肺组的肺功能较铸工尘肺明显下降。吸烟组肺功能测定结果低于不吸烟者,尤其是矽肺组,两组有显著性差异(P〈0.05)。77例尘肺病例中,44例尘肺病人为轻度损伤,其中矽肺33例,铸工尘肺11例,可定为伤残六级,33例尘肺肺功能测定正常,全部为铸工尘肺,伤残等级为七级。结论:我们测定的四项指标中有2项或2项以上指标有改变,并结合临床结果一致时,可诊断为该级别肺功能损伤较为合理。  相似文献   
989.
胃癌中hMSH2、p53和PCNA表达的相关性及意义   总被引:4,自引:1,他引:3  
目的:探讨胃癌中hMSH2、p53和PCNA表达的相关性及意义.方法:采用免疫组织化学SP法,检测胃癌、癌旁和胃炎粘膜中hMSH2、p53和PCNA表达情况.结果:1)3种基因产物在胃癌中的阳性率均显著高于非癌组织,其中,p53和PCNA在低分化癌中的阳性率显著高于高分化癌,有淋巴结转移者显著高于无转移者(P<0.05).2)胃癌中hMSH2/PCNA及p53/PCNA表达均呈正相关(P<0.05).结论:hMSH2、p53和.PCNA的异常表达及hMSH2与PCNA之间的相互调节可能与胃癌的发生发展密切相关.  相似文献   
990.
Several recent studies have suggested that thought leaders in radical prostatectomy have decreased their own positive margin rates by switching from open to robot-assisted radical prostatectomy. Theoretically, this improvement is largely attributed to enhanced visualization of the deep pelvis and precision of dissection afforded by the instrumentation. To date, it has not been determined if this phenomenon exists amongst non-fellowship-trained urologists in private practice. Herein, we describe the positive margin rates of two non-fellowship-trained private-practice urologists who converted from open radical retropubic prostatectomy to robot-assisted radical prostatectomy. The margin positivity data from two non-fellowship-trained private-practice urologists (surgeon 1 and surgeon 2) were reviewed retrospectively. The last 50 cases of open radical retropubic prostatectomy from each surgeon were compared with the first 50 robotic prostatectomy cases of surgeons 1 and 2, respectively. A positive surgical margin was defined as tumor present at the inked margin of the prostate. There was a significant decrease in the overall and pT2 positive margin rates for both surgeons. The overall positive margin rate and pT2 positive margin rate for surgeon 1 dropped from 44 to 20% and from 37 to 5.7%, respectively, after changing from open to robotic prostatectomy. For surgeon 2, the overall positive margin rate changed from 26 to 18% and the pT2 positive margin rate changed from 27.5 to 7% after converting. Changing from open to robotic-assisted radical prostatectomy may improve the ability of urologists to obtain negative surgical margins. With proper training this phenomenon does seem to apply to non-fellowship-trained urologists in private practice and can be realized within the first 50 cases performed.  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