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   2498篇
  免费   239篇
  国内免费   9篇
耳鼻咽喉   7篇
儿科学   99篇
妇产科学   63篇
基础医学   302篇
口腔科学   76篇
临床医学   334篇
内科学   498篇
皮肤病学   22篇
神经病学   127篇
特种医学   201篇
外科学   301篇
综合类   97篇
一般理论   2篇
预防医学   274篇
眼科学   52篇
药学   162篇
中国医学   1篇
肿瘤学   128篇
  2022年   13篇
  2021年   32篇
  2020年   27篇
  2019年   37篇
  2018年   66篇
  2017年   36篇
  2016年   50篇
  2015年   63篇
  2014年   67篇
  2013年   102篇
  2012年   88篇
  2011年   99篇
  2010年   87篇
  2009年   80篇
  2008年   93篇
  2007年   87篇
  2006年   84篇
  2005年   78篇
  2004年   62篇
  2003年   59篇
  2002年   58篇
  2001年   59篇
  2000年   59篇
  1999年   47篇
  1998年   58篇
  1997年   52篇
  1996年   67篇
  1995年   45篇
  1994年   35篇
  1993年   43篇
  1992年   48篇
  1991年   54篇
  1990年   67篇
  1989年   66篇
  1988年   56篇
  1987年   40篇
  1986年   50篇
  1985年   55篇
  1984年   41篇
  1983年   40篇
  1982年   27篇
  1981年   27篇
  1980年   19篇
  1979年   37篇
  1978年   25篇
  1977年   17篇
  1976年   33篇
  1975年   16篇
  1970年   14篇
  1969年   17篇
排序方式: 共有2746条查询结果,搜索用时 15 毫秒
31.
32.
<正>To the Editor:Ischemia-reperfusion injury following surgery and transplantation can lead to irreversible multiorgan failure.Intracellular calcium overload is associated to cellular death during ischemiareperfusion.A recently discovered heparin fragment (HF),trisulfated disaccharide (TD),that acts on sodium-calcium exchanger(NCX) decreasing intracellular Ca2+,showed effectiveness on protecting hepatocytes from ischemia-reperfusion injury [1],  相似文献   
33.
34.
35.
BACKGROUND: We reviewed the outcomes of oropharyngeal squamous cell carcinoma treated with external beam radiation and interstitial brachytherapy. METHODS: Ninety patients with squamous cell carcinoma of the oropharynx were treated with interstitial brachytherapy at the University of Utah between 1984 and 2001. Seventy-two patients received external beam radiotherapy (EBRT) followed by brachytherapy boost, 11 had surgery followed by EBRT and brachytherapy, 4 had surgery and brachytherapy, and 3 were treated with brachytherapy alone. Median doses for EBRT and brachytherapy were 50 and 24 Gy, respectively. RESULTS: Median follow-up after brachytherapy was 48.3 months for all patients. Five-year local control, disease-free survival, and overall survival were 76%, 61%, and 55%. For T1, T2, T3, and T4, 5-year local control rates were 83%, 79%, 79%, and 64%, respectively. Severe complications occurred in 13 patients, including 2 treatment-related deaths. CONCLUSIONS: EBRT combined with interstitial brachytherapy provide good local control rates for locally advanced oropharyngeal squamous cell carcinoma.  相似文献   
36.
37.
Homans  AC; Forman  EN; Barker  BE 《Blood》1985,66(6):1321-1325
The identification of small numbers of leukemic cells in the cerebrospinal fluid (CSF) presents a diagnostic problem in the treatment of children with acute lymphoblastic leukemia (ALL). We adapted a latex sphere rosetting technique to allow us to identify simultaneously cell surface markers and cell morphology in 199 CSF samples from 34 patients and 14 control subjects. In patients without leukemic meningitis, the majority of CSF lymphocytes (69%) were found to be mature T cells positive for OKT11. A much smaller number of cells (8%) were found to be B cells positive for la. In these children, only 3% of CSF lymphoid cells expressed the common acute lymphoblastic leukemia antigen (CALLA). Similar results were found in the control subjects. By contrast, 28 CSF samples from nine children with varying numbers of CSF lymphoblasts had much greater proportions of CALLA- and la-positive CSF cells (24% to 96%). Leukemic meningitis was present in one of these patients and later developed in four others. However, three patients with small numbers of lymphoblasts present but with low proportions of CALLA-positive CSF cells (less than 5%) subsequently had normal CSF examinations. We found the use of this rosetting technique valuable in providing information complementary to that obtained from cell morphology alone about the possible malignant nature of small numbers of lymphoblast-like CSF cells seen on cytocentrifuge preparations in children with ALL.  相似文献   
38.
Ventral wall hernias are common; despite this, there are no guidelines on the best surgical management. The aim of this study was to examine the types of repair in use for abdominal wall hernias in the West of Scotland over a 3-month period. Data were gathered on 120 patients. There were 60 incisional, 32 umbilical, and 28 epigastric hernias. The main indication for repair was pain (78%), while 12 patients (10%), presented acutely with incarceration or strangulation. The most common method of repair was sutured (55%), followed by mesh (29%) and Mayo repair (16%). There was no correlation between use of mesh and hernia size or whether repair was for a recurrent hernia. Surgical practice varies widely in the repair of ventral wall hernias. Clinical trials are required to establish the best method of repair for this common condition. Electronic Publication  相似文献   
39.
Background: Access to diagnostic endoscopy is limited in rural and remote Western Australia. Published reports suggest open access referrals may result in over‐servicing, this is reduced by adherence to the American Society for Gastrointestinal Endoscopy (ASGE) guidelines.The aim was to assess whether an out reach surgical service offering open access endoscopy to rural areas was being over utilized. Methods: Prospective data collection from all patients undergoing upper and lower endoscopy procedures between January 1996 and June 2000 were included in the present study. Indications for referral between the general practitioners and the visiting surgeons were reviewed in patient records and assessed for compliance with the ASGE guidelines. The groups were analysed for appropriateness of referrals and frequency of positive pathology investigations. Records for all patients undergoing colonoscopy were reviewed to determine the reason and number of cancelled procedures. Results: A total of 772 endoscopies were performed and 75% were booked as open access services. The referral rate for procedures was greater for general practitioners (583) compared to the visiting surgeons (189), the overall compliance rate for approved indications using the ASGE guidelines for both groups was 92%. There was no significant difference in pathology found between groups. Conclusion: The present study shows that an outreach rural surgical service programme in Western Australia offering open access endoscopy conforms to international guidelines and does not induce unnecessary procedures. Rural patients benefit from a personal cost savings andconvenience. There is an associated reduction in government‐assisted travel costs to larger centres as well as decreased waiting lists.  相似文献   
40.
BACKGROUND: Ischemic mitral regurgitation has been associated with diminished survival compared with nonischemic mitral regurgitation. Conversion from mitral valve replacement to valve repair has improved prognosis, but it is unclear whether ischemic mitral regurgitation remains an independent predictor of outcome after mitral valve repair. METHODS: Five hundred thirty-five patients undergoing mitral valve repair (primarily rigid ring annuloplasty) with or without coronary bypass from 1993 through 2002 were reviewed retrospectively (ischemic mitral regurgitation, n = 141; nonischemic mitral regurgitation, n = 394). A Cox proportional hazards model evaluated survival as a function of 9 simultaneous covariates: ischemic versus nonischemic mitral regurgitation, age, sex, number of medical comorbidities, ejection fraction, New York Heart Association class, coronary disease, reoperation, and year of operation. RESULTS: According to univariable analysis, patients with ischemic mitral regurgitation had greater age, higher comorbidity, lower ejection fraction, higher New York Heart Association, and higher reoperation rate (all P < .001) compared with those having nonischemic mitral regurgitation. Univariable 30-day mortality was as follows: 4.3% for patients with ischemic mitral regurgitation versus 1.3% for patients with nonischemic mitral regurgitation (P = .01). Unadjusted 5-year mortality was as follows: 44% +/- 5% for patients with ischemic mitral regurgitation versus 16% +/- 3% for patients with nonischemic mitral regurgitation (P < .001). In the multivariable model, however, only the number of preoperative comorbidities and advanced age were independent predictors of survival (P < .0001), whereas ischemic mitral regurgitation, sex, ejection fraction, New York Heart Association class, coronary disease, reoperation, and year of operation did not achieve significance (all P > .19). After being adjusted for differences in all preoperative risk factors, survival was not statistically different between ischemic mitral regurgitation and nonischemic mitral regurgitation (P = .33). CONCLUSIONS: With routine application of rigid ring annuloplasty, long-term patient survival is more influenced by baseline patient characteristics and comorbidity than by ischemic cause of mitral regurgitation per se. Future risk assessment and decision making should be based on patient condition and should not be biased by ischemic cause of mitral regurgitation.  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