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   41387篇
  免费   2254篇
  国内免费   144篇
耳鼻咽喉   537篇
儿科学   2616篇
妇产科学   737篇
基础医学   4903篇
口腔科学   1154篇
临床医学   2987篇
内科学   7544篇
皮肤病学   1129篇
神经病学   2453篇
特种医学   1253篇
外科学   6274篇
综合类   1319篇
一般理论   17篇
预防医学   2135篇
眼科学   1500篇
药学   4114篇
  1篇
中国医学   354篇
肿瘤学   2758篇
  2023年   343篇
  2022年   974篇
  2021年   1684篇
  2020年   907篇
  2019年   1019篇
  2018年   1429篇
  2017年   1034篇
  2016年   1358篇
  2015年   1365篇
  2014年   2027篇
  2013年   2300篇
  2012年   3226篇
  2011年   3176篇
  2010年   1892篇
  2009年   1492篇
  2008年   2123篇
  2007年   2162篇
  2006年   1962篇
  2005年   1744篇
  2004年   1602篇
  2003年   1354篇
  2002年   1194篇
  2001年   819篇
  2000年   746篇
  1999年   618篇
  1998年   282篇
  1997年   223篇
  1996年   225篇
  1995年   194篇
  1994年   157篇
  1993年   132篇
  1992年   363篇
  1991年   354篇
  1990年   372篇
  1989年   348篇
  1988年   304篇
  1987年   269篇
  1986年   250篇
  1985年   243篇
  1984年   183篇
  1983年   131篇
  1982年   74篇
  1981年   86篇
  1980年   75篇
  1979年   131篇
  1978年   80篇
  1977年   96篇
  1976年   75篇
  1973年   72篇
  1971年   65篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
141.
Food systems are complex and inhomogeneous in nature. Ultrasonic propagation velocity in the food systems, in this case processed milk cream and vegetable oils, is studied. Ultrasonic properties of the food systems are similar to those of complex biological tissues. The presence of vegetable oil as an adulterant in the processed milk cream is detected with the help of a double-probe-through-transmission ultrasonic technique. The present study helps to maintain quality control of various food systems, particularly with regard to their adulteration, if any.  相似文献   
142.
OBJECTIVE--To assess the value of dobutamine over dipyridamole as a pharmacological stressing agent in myocardial perfusion imaging with thallium-201. DESIGN--Stress and redistribution tomographic images were taken in a group of patients in a randomised crossover study of both agents. The scans were scored to give a value for the stress and redistribution images and a reversibility score (redistribution--stress). All patients had coronary angiography that was also scored. Differences between the two agents were compared by a paired t test. PATIENTS--30 patients aged 51-70 years with chest pain thought to be caused by myocardial ischaemia. 11 had had previously myocardial infarction. RESULTS--Dipyridamole caused adverse symptoms in six patients whereas dobutamine caused symptoms in 21 patients (chi 2 = 15.15, p < 0.0001). Dobutamine stress took considerably longer than dipyridamole (31 v 6 minutes) and cost more (17 pounds v 1.50 pounds). There were no significant differences between the agents in terms of total stress or redistribution scores, but regional analysis showed that dipyridamole showed significantly more defects during stress at the apex and lateral wall (p < 0.05), with no significant difference at redistribution. Dipyridamole stress also caused significantly more reversible defects at the apex (p < 0.05) and gave a better correlation than dobutamine with coronary score (dipyridamole r = 0.80, p < 0.001 v dobutamine r = 0.64, p < 0.001). In six patients who had continued to take beta blockers the results of dobutamine stress did not correlate with coronary score, r = 0.34 (NS), whereas dipyridamole studies were not affected. CONCLUSION--Compared with dobutamine, dipyridamole was as effective in producing overall perfusion defects and more effective in provoking defects at the apex and lateral segment. The dipyridamole study correlated better with coronary score and was not affected by concurrent beta blocker treatment. It was also better tolerated by the patients, was less time consuming, and was much cheaper.  相似文献   
143.
144.
145.
We report a cast of ossifying fibroma of the nose, arising from the bony septum and extending into the nasophaynx in a 2 yrs. old child presenting with features of obstructed nose.  相似文献   
146.
Background Exploratory laparoscopy is commonly undertaken in patients with highly suspicious biliary and pancreatic lesions to facilitate diagnosis and staging cancer is present. If an unresectable tumor is identified, a second endoscopic procedure may be required do deploy a self-expandable metal stent (SEMS) for palliation. As endoscopic retrograde cholangio pancreatography (ERCP) may be unsuccessful in up to 20% of patients, we evaluated the feasibility and safety of deployment of self-expandable metal stents at the same time as the initial laparoscopy. Patients and Methods A total of 23 eligible patients (8 male and 15 female) with malignant obstruction of the common bile duct underwent deployment of SEMS at laparoscopy. Primary outcome measure was the successful laparoscopic deployment of stent and secondary outcome measure was complications rates. Results Indications for stent deployment were unresectable pancreatic cancer in 18, cholangiocarcinoma in two, neuroendocrine tumor in one and ampullary adenocarcinoma in two patients. The median age was 73 years (range 49–93). Twenty-two of 23 stents were deployed successfully: 17 stents were deployed transcystically and five via a choledochotomy. Median times for laparoscopic exploration and SEMS deployment were 165 min (range 105–230) and 20 min (range 10–50), respectively. Pre- and post-procedures median total bilirubin were 9.4 mg/dl (range 5.4–17.5) and 4.0 (range 2.6–7.1). The median size of the pancreatic mass was 3 cm (range 2–5 cm) and that of the common bile duct (CBD) from 9.2 mm (range 7.2–17.4). The mean duration of laparoscopy was 170 min (range 120–230 min) and that for stent deployment 23 min (range 10–50 min). Complications included bleeding, obstruction, and wound infection. Bleeding occurred on day 7 in two patients and on day 30 in one patient; bleeding occurred at the gastrojejunal anastomosis site and was successfully treated with endoscopic hemostasis. A total of three stent obstructions were identified: one each at 60, 90, and 120 days follow-up. All complications were successfully managed endoscopically. There were a total of seven deaths, six as a result of progressive cancer and one of surgical wound infection and ensuing complications. Conclusion This study demonstrates that laparoscopic deployment of self-expandable metal bile duct stents is feasible and safe. This option appears to be a reasonable option in patients with inoperable malignant obstruction of the distal common bile duct.  相似文献   
147.
Two children out of three siblings of a family presented with tiredness, fatigue, and breathlessness for more than 6 months. Examination of peripheral blood smear, bone marrow aspirate, and a positive acidified serum test (HEMPAS) revealed these children to be a case of congenital dyserythropoietic anemia type II. This case is reported because of its rarity.  相似文献   
148.
Editorial     
Evidence-Based Integrative Medicine -  相似文献   
149.
150.
Abstract A young male motorcyclist presented to the Pelvic Unit with an open-book fracture of his pelvis and an acute obstructed direct inguinal hernia. He was managed operatively and made an excellent recovery. Traumatic abdominal wall hernias are rare. This is a unique combination of injuries that the trauma surgeon should be aware of.  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