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   16150篇
  免费   844篇
  国内免费   113篇
耳鼻咽喉   335篇
儿科学   386篇
妇产科学   318篇
基础医学   2765篇
口腔科学   372篇
临床医学   1468篇
内科学   2711篇
皮肤病学   422篇
神经病学   1627篇
特种医学   1084篇
外科学   2112篇
综合类   166篇
一般理论   2篇
预防医学   805篇
眼科学   535篇
药学   1133篇
中国医学   19篇
肿瘤学   847篇
  2022年   97篇
  2021年   181篇
  2020年   113篇
  2019年   190篇
  2018年   253篇
  2017年   195篇
  2016年   307篇
  2015年   313篇
  2014年   373篇
  2013年   467篇
  2012年   853篇
  2011年   789篇
  2010年   529篇
  2009年   537篇
  2008年   702篇
  2007年   838篇
  2006年   863篇
  2005年   891篇
  2004年   812篇
  2003年   717篇
  2002年   762篇
  2001年   358篇
  2000年   283篇
  1999年   297篇
  1998年   267篇
  1997年   237篇
  1996年   211篇
  1995年   186篇
  1994年   143篇
  1993年   146篇
  1992年   152篇
  1991年   169篇
  1990年   172篇
  1989年   202篇
  1988年   191篇
  1987年   151篇
  1986年   122篇
  1985年   145篇
  1984年   130篇
  1983年   91篇
  1982年   87篇
  1981年   104篇
  1980年   89篇
  1979年   121篇
  1978年   87篇
  1977年   102篇
  1976年   87篇
  1975年   85篇
  1974年   83篇
  1972年   83篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Newborns with respiratory distress and nasal obstruction must be examined for congenital dacryocystocele. This disease is caused by a stenosis in the proximal and distal area of the nasolacrimal duct and leads to a cystic dilatation of this duct. A case of a newborn with bilateral dacryocystocele and dyspnoea is presented. The otorhinolaryngologic as well as the paediatric examination could only reveal in the rhinoscopic examination a tumor of the left nasal cavity that partly obstructed the endonasal space. No other pathologic findings were detected. To clarify the origin and the localization of the tumor as well as to exclude an intracranial relation, a magnetic resonance imaging of the middle face and the frontal skull base was performed. After probe and rinsing of the lacrimal ducts the symptoms improved rapidly. In newborns with nasal obstruction a bilateral rhinoscopy of the lower nasal meatus is required to exclude the existence of a dacryocystocele.  相似文献   
992.
993.
Objectives Catecholamines are often used for optimisation of cardiac index and oxygen delivery in high-risk surgical patients; however, infusions of dopamine and dopexamine are associated with dose-dependent hypophysiotropic and thyreotropic properties. The objective was to compare endocrine effects of equipotent inotropic doses of dopexamine, dobutamine and dopamine on prolactin and thyreotropin release perioperatively.Design A prospective, randomised, blinded clinical trial.Setting Adult surgical intensive care unit in a university hospital.Patients Thirty male patients (ASA III) undergoing elective major abdominal surgery.Interventions Patients were randomised to receive dopexamine (DX, n=10), dobutamine (DO, n=10) or dopamine (DA, n=10) on the first postoperative day for 8 h.Measurements and results All patients received a catecholamine infusion in doses adjusted to increase cardiac index by 35% within the first hour. Blood samples were obtained and prolactin and thyreotropin serum concentrations were determined by radioimmunoassays. Mean doses of dopexamine, dobutamine and dopamine used were 0.73±0.27, 4.06±1.95 and 5.0±1.84 µg kg–1min–1, respectively. Cardiac index was increased by 36% (DX group), 38% (DO group) and 38% (DA group). Alterations of oxygen delivery and oxygen consumption were not significantly different between the study groups. Dopexamine and dobutamine had no hypophysiotropic effects. In contrast, dopamine suppressed prolactin and thyreotropin secretion with a maximal effect after 4 h. After dopamine withdrawal, a rebound release of prolactin and thyreotropin was observed.Conclusions In high-risk surgical patients dopexamine or dobutamine produced fewer effects on prolactin and thyreotropin serum concentrations in comparison with DA when used in equivalent dosages.  相似文献   
994.
A 68-year old man with fever chills and a diastolic murmur was diagnosed with aortic-valve endocarditis caused by coagulase-negative Staphylococcus lugdunensis. The clinical condition initially improved with antibiotic therapy. On day seven, transoesophageal echocardiography revealed large abscesses extending from the aortic root to the left ventricular wall. Emergency cardiac surgery was performed successfully and a stentless bioprosthetic valve was inserted. S. lugdunensis endocarditis is known for its aggressive clinical course with valve destruction, abscess formation and embolic complications despite appropriate antibiotics. Antibiotic treatment alone is associated with a high mortality rate which can be reduced by early valve replacement.  相似文献   
995.
OBJECTIVES: Evaluation of safety and effectiveness of the Combitube during general anaesthesia. PATIENTS AND METHODS: 250 patients undergoing general anaesthesia were enrolled in the study. The respective types and duration of surgery, ease of insertion of the Combitube, and potential complications were recorded. Maximum ventilatory pressures and leak fraction were also evaluated in this study. RESULTS: Duration of surgery varied between 20 and 410 min. More than 96% of the blind Combitube insertions were successful at the first attempt, with a mean time of less than 18 +/- 5 seconds (range 12-24 seconds). In 99% of patients the Combitube worked well, and adequate oxygenation and ventilation was possible. All patients were haemodynamically stable during the entire duration of surgery. In all patients, pulse oximetry showed an oxygen saturation of 97 +/- 2% and an end-tidal carbon dioxide of 38 +/- 6 mmHg. Leak fraction, calculated as a fraction of the inspired volume, did not increase to more than 5% up to a ventilation pressure of 40 cm H2O. Superficial laceration occurred in 18 patients (7.2%) without further sequelae. No severe injuries were observed during the study period. CONCLUSION: Ventilation via the Combitube appears to be safe and effective during general anaesthesia. Practice in elective cases is a requirement for successful use in an emergency situation.  相似文献   
996.
997.
998.
999.
1000.
Background Objective of the study was to investigate particular clinicopathological features of colorectal signet-ring cell carcinoma.Methods The data of 34 patients with primary colorectal signet-ring cell carcinoma were compared with those of 4,458 consecutive patients with primary non-signet-ring cell colorectal adenocarcinoma between 1978 and 1999. For outcome analysis patients, after curative resection of signet-ring cell cancer, were matched for age, gender, tumour site and stage with patients suffering from poorly differentiated non-signet-ring cell colorectal adenocarcinoma.Results Signet-ring cell carcinoma patients were significantly younger than patients with non-signet-ring cell colorectal adenocarcinoma (median age 60 years vs 64 years, P=0.033). The most common tumour sites were the rectum (47%) and the right hemicolon (29%). They presented with significantly more advanced tumour stages and a significantly higher frequency of distant metastases (44% vs 21%, P=0.002). The rate of curative resections was significantly lower (35% vs 79%, P<0.001). However, the prognosis after curative resection of signet-ring cell cancer was as poor as in poorly differentiated non-signet-ring cell colorectal adenocarcinoma of the same stage (5-year survival rate 46% vs 57%, p=0.935).Conclusions Colorectal signet-ring cell carcinoma is characterized by diagnosis in more advanced tumour stages resulting in lower rates of curative resection. Prognosis is as poor as in non-signet-ring cell colorectal cancer of low differentiation in the same stage.  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