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   2796篇
  免费   142篇
  国内免费   15篇
耳鼻咽喉   6篇
儿科学   120篇
妇产科学   110篇
基础医学   335篇
口腔科学   38篇
临床医学   167篇
内科学   706篇
皮肤病学   32篇
神经病学   334篇
特种医学   194篇
外国民族医学   10篇
外科学   318篇
综合类   35篇
预防医学   79篇
眼科学   13篇
药学   114篇
中国医学   3篇
肿瘤学   339篇
  2022年   26篇
  2021年   54篇
  2020年   36篇
  2019年   37篇
  2018年   49篇
  2017年   25篇
  2016年   48篇
  2015年   60篇
  2014年   74篇
  2013年   87篇
  2012年   131篇
  2011年   152篇
  2010年   84篇
  2009年   87篇
  2008年   123篇
  2007年   131篇
  2006年   157篇
  2005年   120篇
  2004年   97篇
  2003年   111篇
  2002年   110篇
  2001年   95篇
  2000年   99篇
  1999年   98篇
  1998年   51篇
  1997年   34篇
  1996年   43篇
  1995年   32篇
  1994年   27篇
  1993年   21篇
  1992年   69篇
  1991年   50篇
  1990年   68篇
  1989年   44篇
  1988年   50篇
  1987年   44篇
  1986年   37篇
  1985年   31篇
  1984年   32篇
  1983年   19篇
  1982年   11篇
  1981年   17篇
  1980年   13篇
  1979年   22篇
  1978年   13篇
  1977年   13篇
  1976年   16篇
  1975年   19篇
  1974年   12篇
  1972年   13篇
排序方式: 共有2953条查询结果,搜索用时 15 毫秒
31.
Severe obesity is associated with an increased risk of admission to intensive care units and need for invasive mechanical ventilation in patients with COVID-19. The association of obesity and COVID-19 prognosis may be related to many different factors, such as chronic systemic inflammation, the predisposition to severe respiratory conditions and viral infections. The ketogenic diet is an approach that can be extremely effective in reducing body weight and visceral fat in the short term, preserving the lean mass and reducing systemic inflammation. Therefore, it is a precious preventive measure for severely obese people and may be considered as an adjuvant therapy for patients with respiratory compromise.  相似文献   
32.
33.
BackgroundThe occurrence of early graft failure (EGF) after heart transplantation (Htx) often requires a mechanical circulatory support (MCS) therapy. The aims of our study were to identify risk factors of mechanically supported severe EGF and evaluate their impact on both early and late outcomes.MethodsBetween January 2000 and December 2019, 499 consecutive adult patients underwent Htx at our institution. Severe EGF was defined as the need for extracorporeal life support (ECLS) within 24 hours after surgery. All available recipient and donor variables were retrospectively analyzed.ResultsOverall, EGF occurred in 58 (11.6%) patients. Post-Htx peripheral or central ECLS was necessary in 32 (6.4%) cases. Independent predictors of severe EGF were, in the recipient group, preoperative transpulmonary gradient (TPG) >12 mm Hg (odds ratio [OR] 4.1, P = .013), preoperative inotropic score >10 (OR 7.3, P = .0001), and pre-Htx ECLS support (OR 5.2, P = .015), while in the donors, a Eurotransplant donor score ≥17 (OR 8.5, P = .005). The absence of EGF was related with a better survival at 1 year and 5 years (94% and 85%, respectively) compared with EGF requiring ECLS population (36% and 28% at 1 year and 5 years, respectively; P < .001). A five-year conditional survival rate did not differ significantly (85% no EGF vs 83% EGF requiring ECLS).ConclusionBoth donor and recipient factors may influence EGF occurrence. Post-Htx ECLS may impact negatively early; however, patients weaned from ECLS eventually benefit from such a rescue treatment with outcomes comparable with Htx patients who did not suffer EGF.  相似文献   
34.
Summary -Aminoadipic acid (AA) is an intermediate in lysine metabolism. We report a new case with AA excess in urine and plasma, without -ketoadipic acid, in a full-term male child born to unrelated parents; he presented at 24h of life with seizures that failed to respond to phenobarbital, clonazepam, and Vigabatrin and death occurred on the 38th day of life. Brain imaging suggested antenatal haemorrhage. Small quantities of AA were also detected in the blood and urine of both parents and a healthy brother, all three of whom exhibited the same defect in platelet aggregation as the deceased child. Both parents had decreased levels of plasma neopterin, a finding that might be related to the immunodeficiency described in other cases.  相似文献   
35.
36.
37.
INTRODUCTION: The healing process of tendon grafts used in cruciate ligament reconstruction is called ligamentization. The tendon structural architecture changes progressively into the histological appearance of normal ligament. Amiel and Clancy have demonstrated that this process is time-dependent in anterior cruciate ligament (ACL) reconstruction, the tendon graft taking one year to become similar to a normal cruciate ligament. Three different maturation phases of anterior cruciate graft ligamentization can be seen at MRI: periligamentous proliferation, intraligamentous proliferation and definitive healing. We report our MR findings in the reconstruction of single ACL, posterior cruciate ligament (PCL), and of both ACL and PCL. MATERIAL AND METHODS: January 1995 to January 1999 we selected 60 patients submitted to arthroscopic cruciate ligament reconstruction. The ACL was reconstructed with the patellar tendon in 22 cases and the PCL in 23; fifteen patients underwent double reconstruction of ACL, with hamstring tendons, and PCL, with patellar tendons. Fifty-five patients were followed-up with MRI: 45 with a dedicated permanent magnet (Artroscan, Esaote Biomedica, Genoa, Italy) and 10 with a permanent low-field unit (AIRIS, Hitachi, Japan); the same technical parameters were used in all cases. Forty of 55 patients were examined at 1, 3, 6, 9 and 12 postoperative months, while 15 were followed-up longer (12 to 36 months postoperatively). At the first follow-up MR examination, 5 patients (2 ACL and 3 PCL) were excluded for incorrect tunnel position (1 case), hypertrophic scarring (2 cases) and new trauma (2 cases). MR findings were compared with clinical data of joint stability. RESULTS: MRI showed the different stages of the healing process in 20 ACL patients: proliferating soft tissue around the graft with the low signal intensity typical of tendons (stage I, 1-3 months postoperatively), the graft becomes progressively hyperintense (stage II, 3-9 months postoperatively), and finally the low signal intensity indicating completed ligamentization (stage III, 12 months postoperatively). As for PCL reconstructions, MR findings were similar but the process took longer, even 24 months. Finally, in the 15 cases of double reconstruction, both grafts were difficult to distinguish on T1-weighted images for a very long time (24-36 months postoperatively). DISCUSSION AND CONCLUSIONS: Relative to the ACL, ligamentization takes longer for PCL and combined ACL and PCL reconstructions, probably because the morphological changes in PCL and double grafts may be impaired by many factors, such as gravity, long bone tunnels, hemarthrosis, hyperplastic synovial reaction in the intercondylar notch; also, rehabilitation protocols differ in ACL from PCL patients. No signs of instability were found at physical or arthrometric examinations. MRI demonstrates the different stages of ligamentization and thus proves a useful tool for postoperative follow-up in cruciate ligament reconstructions. Contrast-enhanced (Gd) studies are reserved to the cases of graft impingement or if other abnormalities are suspected.  相似文献   
38.
This prospective study was conducted to evaluate the risk of nosocomial pneumonia when changing heat and moisture exchangers every 48 hours in 1996 instead of every 24 hours in 1995 for patients needing continuous mechanical ventilation. Medical and surgical patients in the two periods did not differ in terms of demographic characteristics and markers of acute or underlying illnesses. The incidence density of nosocomial pneumonia was not different in the two groups. Extended heat and moisture exchanger use reduces circuit manipulation and cost.  相似文献   
39.
Over a follow-up period of 6 years, 4 out of 31 live related renal allograft recipients (12.9%) developed azathioprine induced bone marrow suppression. Presentation in 3 patients was with fever and 2 patients also had associated graft dysfunction. All patients had leucopenia, 2 patients in addition had anaemia and one patient had pancytopenia. Bone marrow suppression developed 9.6 months (3.5-16.0 months) following transplantation and recovery followed over a period of 30 (18-49 days) days after withdrawal of the drug. One patient succumbed during the phase of bicytopenia.KEY WORDS: Azathioprine, Bone marrow suppression, Kidney transplantation  相似文献   
40.
Discoid medial meniscus: report of a case treated by arthroscopy   总被引:1,自引:1,他引:0  
A complete discoid medial meniscus with a longitudinal tear was found in a 41-year-old man and treated by arthroscopy. The symptomatology was characterized by a sharp pain corresponding to the medial joint line, slight intrarticular effusion without locking or loss of motion. A review of the literature is described.  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