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   933097篇
  免费   67919篇
  国内免费   1531篇
耳鼻咽喉   12972篇
儿科学   24391篇
妇产科学   23249篇
基础医学   133362篇
口腔科学   28266篇
临床医学   80864篇
内科学   183605篇
皮肤病学   19289篇
神经病学   72363篇
特种医学   36894篇
外国民族医学   80篇
外科学   152387篇
综合类   18350篇
现状与发展   2篇
一般理论   235篇
预防医学   61908篇
眼科学   21384篇
药学   72761篇
  3篇
中国医学   2293篇
肿瘤学   57889篇
  2018年   9072篇
  2017年   7114篇
  2016年   7860篇
  2015年   8998篇
  2014年   12148篇
  2013年   17636篇
  2012年   24291篇
  2011年   25271篇
  2010年   14939篇
  2009年   14424篇
  2008年   24793篇
  2007年   25861篇
  2006年   26669篇
  2005年   25581篇
  2004年   24656篇
  2003年   23700篇
  2002年   23239篇
  2001年   54782篇
  2000年   56587篇
  1999年   47003篇
  1998年   10780篇
  1997年   9494篇
  1996年   9630篇
  1995年   8959篇
  1994年   8296篇
  1993年   7609篇
  1992年   35517篇
  1991年   33928篇
  1990年   32757篇
  1989年   31888篇
  1988年   29006篇
  1987年   28264篇
  1986年   26298篇
  1985年   25161篇
  1984年   17837篇
  1983年   15145篇
  1982年   7795篇
  1981年   6772篇
  1979年   15782篇
  1978年   10600篇
  1977年   9053篇
  1976年   7874篇
  1975年   8629篇
  1974年   10467篇
  1973年   9858篇
  1972年   9358篇
  1971年   8854篇
  1970年   8426篇
  1969年   7923篇
  1968年   7201篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
In-flight encounters with hazardous weather represent one of the most significant safety issues in civil aviation operations. Aircrew judgment is often cited as the probable cause of incidents and accidents involving weather, although lack of information is also a factor. The present study examines how information, presented at different times and in different forms, affects the awareness and decision-making behavior of aircrews in a flight simulation study of a recent microburst/windshear incident. In order to examine the influence of enhanced information transfer on aircrew behavior, intracrew communications and approach-to-land decisions were evaluated with conventional ATC communications and with automated cockpit alerting and display of weather information. Results of the study revealed that aircrews provided only with conventional ATC transmissions of weather information had difficulty discriminating conditions conducive to microburst events from less hazardous windshear events. Improved situation awareness for microburst events was found when ground-based convective weather information was provided in real time to aircrews. Avoidance decision-making was found to be less efficient with conventional ATC alert transmissions when compared to the performance of crews provided with a visual display of microburst events. The importance of information transfer on aircrew situation awareness and decision-making in hazardous weather avoidance is discussed.  相似文献   
992.
993.
994.
995.
996.
The presented report is fibrosarcoma arising from renal capsule in a 64-year-old woman. The tumor is very rare and is the 25th case in Japan. The patient visited our hospital with the complaint of macroscopic hematuria for several days. Abdominal examination revealed a painless lump from the left lumbar region to para-median abdomen. A diagnosis of hydronephrosis caused by neoplasma or tuberculosis was considered by CT, AG, etc., and transperitoneal nephrectomy was performed on 6-July-1984. Pathology of the tumor was fibrosarcoma arising from the renal capsule. Three months later, the tumor was growing on the peritoneal surface from the left renal region and she died on Nov. 10, 1984.  相似文献   
997.
Priapism: a refined approach to diagnosis and treatment   总被引:4,自引:0,他引:4  
The recent introduction of intracorporeal injections of papaverine and phentolamine for the diagnosis and treatment of impotence has resulted in an increased incidence of iatrogenic priapism. Based on our research into penile hemodynamics we propose a refined approach to all types of priapism. Intracorporeal blood gas and pressure monitoring should be used to differentiate ischemic (low flow) from nonischemic (high flow) types. Most cases of papaverine-induced or phentolamine-induced priapism will respond to aspiration alone or in combination with intracorporeal instillation of a diluted alpha-adrenergic agent. In spontaneous priapism alpha-adrenergic agents can be tried first if patients have only mild or no ischemia. In patients with severe ischemia stagnant blood should be evacuated and a shunt procedure should be performed to allow metabolic replenishment of tissue. Intracorporeal pressure monitoring will help to determine the size and number of shunts needed to re-establish corporeal circulation.  相似文献   
998.
The technique and use of a percutaneous subclavian vein catheter for haemodialysis in 20 patients are reported. The catheterization procedure carried a very low morbidity, and blood flow rates of 200–250ml/min were achieved through the catheters. Use of this angioaccess saves future possible sites for permanent vascular access. Infectious complications were not encountered. Subclavian vein catheterization is a favourable alternative to external Silastic Teflon shunt.  相似文献   
999.
Surgery of Dupuytren's disease: a review of the open palm method   总被引:1,自引:0,他引:1  
Experience with 49 cases of Dupuytren's disease treated by the open palm method and followed for an average of 5 years is reported. This method permits excision of the involved fascia while minimizing early postoperative morbidity associated with the surgical management of this condition. There were no cases of wound necrosis, hematoma, or infection with this technique, and all wounds closed spontaneously within 3 to 5 weeks. Long-term follow-up, however, revealed a significant rate of recurrence (32%) and extension (48%), as well as flexion loss at one or more joints in 41% of involved hands. While helpful in the early care of these patients, the open palm method does not modify the long-term results in Dupuytren's disease, which is a pervasive condition without simple surgical solution.  相似文献   
1000.
The effects of methyl 2,6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1,3,2-dioxaphosphorinan-2- yl)-1,4- dihydropyridine 3-carboxylate (DHP-218), a new dihydropyridine calcium antagonist, on vascular smooth muscles, cardiac muscles and [3H]-nitrendipine binding to the cardiac muscle and brain membranes were investigated in vitro. Vascular smooth muscles: Calcium-induced contraction of the rat aorta in high K+ solution was inhibited by DHP-218 with the pA2 value of 9.11. The IC50 value for the inhibitory effects of this compound in high K+-induced and phenylephrine-induced contraction was 6.3 nmol/l and 66 nmol/l, respectively. Vasodilatory effects of this drug on various blood vessels of rabbits contracted by high K+ appeared to a similar extent. The onset of the vasodilatory effect was very slow and the recovery rate of vasodilatory response after washout with the bathing solution containing high K+ or phenylephrine was also very slow. Cardiac muscles: Negative chronotropic and inotropic actions were observed at concentrations more than 30 and 100 nmol/l, respectively. Duration of the plateau phase of normal action potential was shortened and the amplitude and duration of slow action potential were reduced at concentrations more than 1 mumol/l. Very high vasculoselectivity was observed. Displacement of [3H]-nitrendipine binding: The pattern of displacement of [3H]-nitrendipine binding by DHP-218 was very similar to that of other 1,4-dihydropyridines but this compound was about 70 times less potent than nifedipine in [3H]-nitrendipine displacement capacity. These results indicate that DHP-218 has specific vasodilatory action due to calcium antagonism, but association and dissociation rates with tissue and receptors were different from those of nifedipine.  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