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   20357篇
  免费   791篇
  国内免费   98篇
耳鼻咽喉   361篇
儿科学   412篇
妇产科学   194篇
基础医学   2643篇
口腔科学   464篇
临床医学   1099篇
内科学   5099篇
皮肤病学   263篇
神经病学   1540篇
特种医学   750篇
外科学   3446篇
综合类   121篇
预防医学   669篇
眼科学   536篇
药学   1459篇
中国医学   81篇
肿瘤学   2109篇
  2023年   76篇
  2022年   118篇
  2021年   301篇
  2020年   190篇
  2019年   220篇
  2018年   265篇
  2017年   226篇
  2016年   315篇
  2015年   325篇
  2014年   419篇
  2013年   597篇
  2012年   917篇
  2011年   1040篇
  2010年   549篇
  2009年   494篇
  2008年   985篇
  2007年   1157篇
  2006年   1207篇
  2005年   1269篇
  2004年   1301篇
  2003年   1228篇
  2002年   1319篇
  2001年   527篇
  2000年   488篇
  1999年   474篇
  1998年   359篇
  1997年   294篇
  1996年   253篇
  1995年   249篇
  1994年   240篇
  1993年   203篇
  1992年   345篇
  1991年   324篇
  1990年   303篇
  1989年   294篇
  1988年   259篇
  1987年   242篇
  1986年   211篇
  1985年   235篇
  1984年   160篇
  1983年   139篇
  1982年   99篇
  1981年   93篇
  1980年   88篇
  1979年   118篇
  1978年   79篇
  1977年   86篇
  1975年   75篇
  1974年   51篇
  1971年   52篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
2.
BackgroundTIAregistry.org is an international cohort of patients with transient ischemic attack (TIA) or minor stroke within 7 days before enrollment in the registry. Main analyses of 1-year follow-up data have been reported.5 We conducted subanalysis on the baseline and 1-year follow-up data of Japanese patients.MethodsThe patients were classified into 2 groups based on Japanese ethnicity, Japanese (345) and non-Japanese (3238), and their baseline data and 1-year event rates were compared. We also determined risk factors and predictors of 1-year stroke.ResultsCurrent smoking, regular alcohol drinking, intracranial arterial stenosis, and small vessel occlusion; and hypertension, dyslipidemia, coronary artery disease, and extracranial arterial stenosis were more and less common among Japanese patients, respectively. Stroke risk was higher and TIA risk was lower at 1-year follow-up among Japanese patients. The baseline risk factors for recurrent stroke were diabetes, alcohol drinking, and large artery atherosclerosis. Independent predictors of 1-year stroke risk were prior congestive heart failure and alcohol consumption.ConclusionsThe two populations of patients featured differences in risk factors, stroke subtypes, and outcome events. Predictors of recurrent stroke among Japanese patients included congestive heart failure and regular alcohol drinking. Strategies to attenuate residual risk of stroke aside from adherence to current guidelines should take our Japanese-patient specific findings into account.  相似文献   
3.
Carbon monoxide (CO), a byproduct of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. In vivo recipient CO inhalation at low concentrations prevented ischemia/reperfusion (I/R) injury associated with small intestinal transplantation (SITx). This study examined whether ex vivo delivery of CO in University of Wisconsin (UW) solution could ameliorate intestinal I/R injury. Orthotopic syngenic SITx was performed in Lewis rats after 6 h cold preservation in control UW or UW that was bubbled with CO gas (0.1-5%) (CO-UW). Recipient survival with intestinal grafts preserved in 5%, but not 0.1%, CO-UW improved to 86.7% (13/15) from 53% (9/17) with control UW. At 3 h after SITx, grafts stored in 5% CO-UW showed improved intestinal barrier function, less mucosal denudation and reduced inflammatory mediator upregulation compared to those in control UW. Preservation in CO-UW associated with reduced vascular resistance (end preservation), increased graft cyclic guanosine monophosphate levels (1 h), and improved graft blood flow (1 h). Protective effects of CO-UW were reversed by ODQ, an inhibitor of soluble guanylyl cyclase. In vitro culture experiment also showed better preservation of vascular endothelial cells with CO-UW. The study suggests that ex vivo CO delivery into UW solution would be a simple and innovative therapeutic strategy to prevent transplant-induced I/R injury.  相似文献   
4.
A 69-year-old man was admitted to our kidney center with endstage renal failure. We started intermittent peritoneal dialysis immediately because of severe azotemia, hyperkalemia, and metabolic acidosis. Two weeks after admission, he developed uremic pericarditis with frequent ventricular premature contractions and supraventricular premature contractions. The intermittent peritoneal dialysis was then replaced by intensive hemodialysis, and oral administration of 300 mg/d of cibenzoline was started. Four days later, he developed thirst, weakness, and dyspnea due to respiratory muscular paralysis. We initiated respiratory support with a respirator because analysis of his blood gases revealed marked hypercapnia and hypoxia. He also developed hypoglycemia and prolonged PQ and QRS intervals on the electrocardiogram, which we believed were due to cibenzoline intoxication; we discontinued the cibenzoline immediately. All symptoms improved, and he was extubated 5 days later. After 2 months, his pericardial effusion disappeared. He now continues maintenance hemodialysis as an outpatient. We suspect that the cibenzoline induced the respiratory muscular paralysis for 2 reasons: 1) the patient experienced the respiratory muscular paralysis, at the same time he also experienced thirst, weakness, hypoglycemia, and prolonged PQ and QRS intervals on electrocardiogram, and all of these symptoms improved after the discontinuation of cibenzoline, and 2) his plasma concentration of cibenzoline became remarkably elevated, to 20 times above the standard therapeutic level. This patient's clinical course indicates that hemodialysis might be superior to intermittent peritoneal dialysis for treatment of cibenzoline intoxication.  相似文献   
5.
We assessed the efficacy of a government-sponsored mass protection program in Osaka, Japan, for perinatal HBV infection in infants born to HBeAg positive HBV carrier mothers. We also evaluated the impact of optional follow-up procedures in such infants, including an evaluation of anti-HBs response and a booster dose of HBV vaccine for poor responders. The results demonstrated that this mass protection program protected 94.4% of the infants from perinatal HBV infection in the Osaka area. However, the proportion of infants with an unprotective level of anti-HBs was higher in the standard group than in the follow-up group both at 1.0 and 1.5 years of age, which was also the case for HBV events. Furthermore, the present study showed that a booster dose of vaccine in poor responders was very effective in promoting an anti-HBs response. In conclusion, we recommend that a follow-up blood test to confirm a response of anti-HBs to HBV vaccine should be performed at 4–8 weeks after the third injection of HBV vaccine in infants born to HBeAg positive HBV carrier mothers. We also recommend that a booster injection of HBV vaccine should be immediately given to poor responding infants who otherwise are at a considerable risk of developing HBV infection in late infancy.  相似文献   
6.
Proteins in normal human urine were clearly fractionated into 26 bands with molecular weights from 14,000 to 230,000 by means of one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with silver staining. The main band contained uromucoid, and the second main band had albumin. However, when urine samples from healthy persons were electrophoresed in the absence of SDS using polyacrylamide gel or agarose gel, or a cellulose acetate membrane, albumin but not uromucoid, frequently formed the main protein band. It is suggested that this is due to the complexing of uromucoid subunits to form a large molecule which cannot penetrate into the gel. In order to correctly fractionate all the proteins contained in normal human urine, it was concluded that it was best to treat a urine sample with SDS with pre-condensation, fractionate it by SDS-PAGE and stain fractionated proteins by a highly sensitive method such as silver staining.  相似文献   
7.
8.
9.
Definition of carcinoma of the gastric cardia   总被引:8,自引:0,他引:8  
Summary This study concerns the definition of carcinoma of the gastric cardia. The topography of the esophagogastric mucosal junction (mucosal EGJ) was investigated with an endoscope in 182 patients who were free of hiatal hernias, ulcers, and neoplasms in the esophagus and stomach. The relationship between the EGJ and the cardiac gland area was then examined histologically in 56 resected specimens containing intact EGJs and cardia gland areas. Furthermore the cancerous center was determined; the shortest distance between the cancerous center and the EGJ and the amount of esophageal invasion were measured in 102 resected carcinomas located close to the junction; the carcinomas contained the EGJ and were good enough for pathohistological examination. The EGJ was located 0.5–1.0 cm proximal to the His angle (the gastric cardia) in radiological and endoscopic examinations. Histologically the cardiac gland area was found to straddle the EGJ at a range of about 1 cm proximal and 2 cm distal to the junction. Among the upper stomach carcinomas, most of the tumors (87.5%) whose center was located within 2 cm from the EGJ invaded the esophagus. In conclusion, carcinoma of the gastric cardia is defined as a lesion with its center located within 1 cm proximal and 2 cm distal to the EGJ.
Definition des Kardiacarcinoms
Zusammenfassung Diese Untersuchung befaßt sich mit der Definition von Carcinomen der Kardia. An 182 Patienten, die weder Hiatushernien, Ulcera noch Neoplasien des Oesophagus bzw. des Magens aufwiesen, wurde die Lage des Übergangs von der Oesophagus- zur Magenmucosa (esophagogastric mucosal junction, EGJ) endoskopisch untersucht. Dann wurde die Beziehung zwischen EGJ und dem Drüsengebiet der Kardia histologisch anhand von 56 Resektaten mit intaktem EGJ und Kardiadrüsenzone untersucht. Außerdem wurde an 102 resezierten Carcinomen mit Sitz in der Nähe des gastrooesophagealen Übergangs die kürzeste Ent fernung zwischen Carcinomzentrum und EGJ und das Ausmaß der Oesophagusinfiltration bestimmt; die Proben schlossen den EGJ ein und konnten pathohistologisch beurteilt werden. Bei der radiologischen und endoskopischen Untersuchung fand sind der EGJ 0,5–1,0 cm vom His-Winkel entfernt. Die histologische Untersuchung zeigte, daß die Kardiadrüsenzone sich vom EGJ etwa 1 cm nach proximal und 2 cm nach distal erstreckt. Die meisten Tumoren des oberen Magens (87,5%), deren Zentrum innerhalb von 2 cm vom EGJ entfernt lag, infiltrierten in den Oesophagus. Ein Kardiacarcinom ist demzufolge als Läsion zu definieren, deren Zentrum innerhalb von 1 cm proximal und 2 cm distal des EGJ liegt.
  相似文献   
10.
The optimal size of tricuspid valve annular area (TVAA) by annuloplasty for tricuspid regurgitation remains controversial. Recently, we developed a new measuring system which permits to do real-time measurement of tricuspid valve annular area in anesthetized dogs. Using this system, we studied the optimal size of TVAA by annuloplasty. After the right atrial incision, a metal thread which functions as a sense loop of the electromagnetic fields was stitched along the tricuspid valve annulus (visible juncture of the valve leaflets and the cardiac wall). The drive coil assembly was placed perpendicular to the extension of the long axis of the heart and was directed toward the tricuspid valve region. During control conditions, the maximum TVAA appeared at the onset of ventricular systole. The minimum TVAA appeared during the early ventricular diastolic phase which included the ventricular isovolumic relaxation phase. The maximum TVAA varied in five dogs between 2.2 cm2 and 3.1 cm2, the minimum TVAA also varied between 1.8 cm2 and 2.5 cm2: During regular sinus rhythm, a decrease of TVAA during one cardiac cycle ranged between 11.9% and 22.4% of the maximum size. When TVAA was not decreased by annuloplasty to the minimum area which was observed during cardiac cycle in the control state, the cardiac output and the right atrial pressure remained unchanged, because the ventricular filling was not obstructed. On the other hand, when TVAA was decreased smaller than this minimum area, the cardiac output decreased and the right atrial pressure rose.(ABSTRACT TRUNCATED AT 250 WORDS)  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