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   9079篇
  免费   404篇
  国内免费   62篇
耳鼻咽喉   92篇
儿科学   92篇
妇产科学   73篇
基础医学   1066篇
口腔科学   300篇
临床医学   728篇
内科学   1978篇
皮肤病学   282篇
神经病学   576篇
特种医学   466篇
外科学   1681篇
综合类   52篇
一般理论   1篇
预防医学   461篇
眼科学   79篇
药学   716篇
中国医学   30篇
肿瘤学   872篇
  2023年   44篇
  2022年   75篇
  2021年   163篇
  2020年   99篇
  2019年   134篇
  2018年   177篇
  2017年   115篇
  2016年   155篇
  2015年   152篇
  2014年   203篇
  2013年   254篇
  2012年   433篇
  2011年   482篇
  2010年   276篇
  2009年   201篇
  2008年   377篇
  2007年   429篇
  2006年   400篇
  2005年   393篇
  2004年   393篇
  2003年   373篇
  2002年   348篇
  2001年   307篇
  2000年   316篇
  1999年   304篇
  1998年   134篇
  1997年   79篇
  1996年   72篇
  1995年   81篇
  1994年   71篇
  1993年   50篇
  1992年   218篇
  1991年   197篇
  1990年   216篇
  1989年   219篇
  1988年   176篇
  1987年   193篇
  1986年   160篇
  1985年   156篇
  1984年   101篇
  1983年   82篇
  1982年   40篇
  1981年   51篇
  1979年   95篇
  1978年   41篇
  1977年   52篇
  1974年   47篇
  1971年   40篇
  1969年   45篇
  1968年   40篇
排序方式: 共有9545条查询结果,搜索用时 578 毫秒
51.
Prostaglandin E1 (PGE1) has several potential therapeutic effects, including cytoprotection, vasodilation, and inhibition of platelet aggregation. This study investigates the protective action of PGE1 against hepatic ischemia/reperfusion injury in vivo using a complementary DNA microarray. PGE1 or saline was continuously administered intravenously to mice in which the left lobe of the liver was made ischemic for 30 minutes and then reperfused. Livers were harvested 0, 10, and 30 minutes postreperfusion. Messenger RNA was extracted, and the samples were labeled with two different fluorescent dyes and hybridized to the RIKEN set of 18,816 full-length enriched mouse complementary DNA microarrays. Serum alanine aminotransferase and aspartate aminotransferase levels at 180 minutes postreperfusion were significantly lower in the PGE1-treated group than in the saline-treated group. The cDNA microarray analysis revealed that the genes encoding heat-shock protein (HSP) 70, glucose-regulated protein 78, HSP86, and glutathione S-transferase were upregulated at the end of the ischemic period (0 minutes postreperfusion) in the PGE1 group. Our results suggested that PGE1 induces HSPs immediately after ischemia reperfusion. HSPs might therefore play an important role in the protective effects of PGE1 against ischemia/reperfusion injury of the liver.  相似文献   
52.
Conclusions  Reduced utilization of fatty acids at rest often is observed in severely ischemic myocardium and possibly postischemic myocardium despite normal perfusion at rest. The role of metabolic imaging in identifying postischemic insult as ischemic memory imaging has been the focus of recent investigations. A number of reports from Japan show quite acceptable diagnostic accuracy of BMIPP imaging for detecting coronary patients without prior MI. In addition, recent data indicate that BMIPP imaging has prognostic value when applied in patients with documented or suspected coronary disease. The major advantage of BMIPP imaging is to demonstrate ischemic myocardium as an area of altered metabolism at rest. Thus this study is of clinical importance for elderly patients or for patients not suitable for a stress study. Furthermore, this radiopharmaceutical tracer may hold promise in demonstrating early alteration of energy metabolism in a variety of myocardial disorders.  相似文献   
53.
We performed myocardial revascularization with bilateral internal mammary arteries in eight children for coronary artery complications consequent to Kawasaki disease. Subjects included seven boys and one girl, ranging in age from 3 to 13 years (mean age, 8.3 +/- 3.4 years). The body surface area ranged from 0.65 to 1.65 m2 (average, 1.08 +/- 0.35 m2). Three patients had a previous myocardial infarction. The right internal mammary artery was anastomosed to the right coronary artery and the left internal mammary artery was sutured to the left anterior descending artery in all patients. The patients received an average of 2.4 grafts. Magnifying loupes of 3.5 X were used for anastomosis with 8-0 monofilament polypropylene sutures. Subjects were followed up from 12 to 38 months (23 +/- 10.8 months) after operation. All were doing well with no recurrence of angina, and body development was normal, including the sternum and thorax according to chest x-ray films and computed tomography of the chest. Patency of the bilateral internal mammary arteries was 100% in the early (within 1 month) postoperative period and remained so in the late (over 1 year) postoperative period. Anastomotic junctions between the internal mammary artery and the coronary artery developed well angiographically in the late postoperative period. The internal mammary artery is the graft of choice for pediatric myocardial revascularization because of its excellent long-term patency and growth potential. Bilateral internal mammary arteries should be used whenever indicated, and the use of bilateral internal mammary arteries did not adversely influence chest wall development in the children.  相似文献   
54.
Forty-nine patients with 63 cystic thyroid masses who had undergone preoperative sonography were retrospectively reviewed. 52 lesions (83%) were benign and others (17%) were malignant. Among various sonographic findings of cystic thyroid masses, oval cystic lesions with polyp or dome like solid component projecting into the lumen were all diagnosed adenomatous goiter. Irregular cystic structures with more than 2 cm finger like pedunculated mass extended into and/or out of the lumen were all diagnosed papillary carcinoma. Small oval cysts (less than or equal to 1 cm) with strong echo were all diagnosed colloid goiter. The other sonographic type of cystic thyroid masses had somewhat malignancy (12-30%), not having characteristics which differentiate benign from malignant lesions. Pathologic findings of malignant lesions showed that cancer cells existed rather in pericystic portion than in cyst wall except for finger like solid component projecting into the lumen which was papillary carcinoma itself. Ultrasonically guided needle biopsy should be performed to get samples of above portions.  相似文献   
55.
Ten patients with early stage esophageal carcinoma were treated with hyperthermo-chemo-radiotherapy (HCR) without surgery. The reasons for the inoperability of these patients included medically inoperable unresectable cancers, advanced age, and/or refusal to undergo surgery. The diagnosis of early esophageal carcinoma was determined by esophagograms, endoscopy, and ultrasonography. Squamous cell carcinoma was histopathologically confirmed in each case. Each patient underwent four to nine sessions of hyperthermic treatment combined with external irradiation and chemotherapy using bleomycin; eight of these patients received additional radiation, and two terminated treatment after the HCR therapy. The tumors in all patients showed either a complete response (CR) or a partial response (PR) after HCR therapy; in two patients viable cancer cells remained, but later disappeared after additional radiation. Five patients experienced no local recurrence for 12 to 70 months and are now alive and doing well, three died of other medical conditions without any evidence of esophageal cancer, and two died of recurrent esophageal cancer 20 to 27 months after initial admission. All ten patients tolerated the HCR well without any systemic side effects. However, in two patients, esophageal erosion was recognized endoscopically. HCR therapy therefore deserves serious consideration when treating patients with small malignant lesions of the esophagus who, for various reasons, are unable to undergo surgery.  相似文献   
56.
Currently, heterogeneity is the word to describe any inhomogeneous phenomenon observed in the ever changing living creatures. Myocardial function is dynamic in nature which is a summation of many inhomogeneous components. In fact, heterogenic phenomenon has been observed both at cellular and at ventricular levels during myocardial contraction and relaxation. However, this heterogenic behavior of myocardial activities serves as a source of monitoring parameters by which we can grasp what is happening in the patient. Reliance on only one of those parameters would lead to a wrong diagnosis and judgement in the heterogenic world. We, therefore, need to integrate those parameters to form more realistic image about patient's status. We have to have a cut off point to divide what is right and what is wrong. Although the truth may not be reached eventually from heterogeneous informations, an appropriate method to integrate informations in the heterogenic world will aid us to come closer to the reality.  相似文献   
57.
The spontaneous contractile force of muscle strips isolated from male rabbit urinary bladder dome [detrusor) and base (trigonal muscle) was dose dependently inhibited by isoproterenol, a non-specific beta-adrenoceptor agonist. The relaxant response to 10(-6) M isoproterenol in the detrusor muscle was completely blocked by butoxamine (10(-4) M), a selective beta-2-antagonist, and by propranolol (10(-6) M), a non-specific beta-antagonist, but not by metoprolol (10(-6) to 10(-4) M), a selective beta-1-antagonist. Relaxation of trigonal muscle induced by 10(-6) M isoproterenol was inhibited 30% by metoprolol (10(-5) M), 70% by butoxamine (10(-4)M), and 100% by propranolol (10(-6) M). Terbutaline, a selective beta-2-adrenoceptor agonist, also caused dose dependently a relaxant response in detrusor and trigonal muscle. The maximum relaxant responses to isoproterenol and terbutaline were significantly greater in detrusor than in trigonal muscle. Dobutamine, a relatively specific beta-1-adrenoceptor agonist, caused a small but significant relaxant response in trigonal, but no change in detrusor muscle. In trigonal muscle the relaxant response to dobutamine was less than that to terbutaline. Cyclic adenosine monophosphate accumulation in detrusor did not significantly increase after administration of dobutamine, but significantly increased after administration of terbutaline. On the other hand, not only terbutaline, but also dobutamine, markedly increased cyclic adenosine monophosphate accumulation in trigonal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
58.
Optimal initial palliation and a subsequent staged approach is mandatory for high-risk Fontan candidates. We describe the case of mitral atresia with severe tricuspid regurgitation and pulmonary hypertension successfully managed by repeated palliation from the neonatal period and 2-stage Fontan surgery. A 1-month-old boy diagnosed with mitral atresia and double-outlet right ventricle underwent pulmonary artery banding at 1 month of age, followed by repeated pulmonary artery banding accompanied by tricuspid annuloplasty and atrial septal defect enlargement at 6 months. Because of the presence of pulmonary artery distortion, right ventricular dysfunction, and borderline pulmonary vascular resistance, a hemi-Fontan procedure was conducted with extended pulmonary artery plasty when the boy was 3 years and 8 months old. Cardiac catheterization done 3 months after showed improvement in risk factors, and the final Fontan operation (total cavopulmonary connection) was successfully done in conjunction with repeated tricuspid annuloplasty when the boy was 4 years and 5 months old. The patient remains in excellent clinical condition at the last follow-up 5 years after the final Fontan procedure with sinus rhythm and good ventricular function.  相似文献   
59.
Summary A human glioma cell line (YKG1), which was positively identified for glial fibrillary acidic (GFA) and S-100 proteins, was established from a surgical specimen of a patient with glioblastoma. Chromosome analysis of the cells revealed a homogeneously staining region (HSR) on a marker chromosome. The assay for transforming growth factors (TGFs) in the conditioned medium of the cell line revealed that it contained high levels of - and -type TGFs, which might regulate the growth of glioblastoma and influence on the peritumoral tissues.  相似文献   
60.
Calcified stenotic aortic valve are usually replaced by the artificial valve. Recently, we are trying to decalcify the calcification of the aortic valve by ultrasonic energy. This case report reviewed a small physique, 47 year old female, who had the calcified stenotic bicuspid aortic valve and the narrow aortic valve ring (18 mm diameter). The ultrasonic decalcification was performed by the ultrasonic surgical instrument, SUS-201D (ALOKA), ultrasonic energy output range from 25% to 45%. After the ultrasonic decalcification, the movability of the aortic cusps were improved and the aortic opening was enlarged. The systolic pressure gradient across the aortic valve was improved from 100 mmHg to 20 mmHg. This method "ultrasonic decalcification" is very useful technique for the repair of the calcified aortic valve stenosis.  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