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   519篇
  免费   28篇
耳鼻咽喉   7篇
儿科学   11篇
妇产科学   7篇
基础医学   100篇
临床医学   52篇
内科学   132篇
皮肤病学   5篇
神经病学   9篇
特种医学   43篇
外科学   91篇
综合类   1篇
预防医学   1篇
眼科学   5篇
药学   26篇
肿瘤学   57篇
  2015年   7篇
  2013年   13篇
  2012年   13篇
  2011年   9篇
  2010年   14篇
  2009年   10篇
  2008年   20篇
  2007年   9篇
  2006年   24篇
  2005年   17篇
  2004年   26篇
  2003年   27篇
  2002年   31篇
  2001年   16篇
  2000年   12篇
  1999年   15篇
  1998年   6篇
  1997年   7篇
  1996年   5篇
  1995年   5篇
  1993年   4篇
  1992年   9篇
  1991年   10篇
  1990年   13篇
  1989年   18篇
  1987年   10篇
  1986年   9篇
  1985年   6篇
  1984年   4篇
  1982年   4篇
  1980年   4篇
  1979年   13篇
  1976年   4篇
  1974年   4篇
  1967年   6篇
  1966年   5篇
  1965年   7篇
  1959年   6篇
  1958年   4篇
  1942年   4篇
  1939年   4篇
  1936年   6篇
  1935年   4篇
  1934年   3篇
  1933年   7篇
  1932年   5篇
  1931年   3篇
  1928年   4篇
  1927年   4篇
  1921年   4篇
排序方式: 共有547条查询结果,搜索用时 210 毫秒
1.
2.
3.
Primary anatomical repair of TGA has several theoretical advantages over conventional atrial baffle techniques. However, one of the most common postoperative complications of the new technique is the development of an obstruction at the arterial anastomosis to the pulmonary artery (PA). A supravalvular pulmonary stenosis developed progressively over the first months after an arterial switch operation of a simple TGA in a newborn infant. The diagnosis was easily performed by Doppler-echocardiographic follow-up studies. Hemodynamic assessment by cardiac catheterization performed when the patient was five months old revealed a systolic gradient of 76 mm Hg at the arterial anastomosis. Percutaneous balloon angioplasty was successfully performed.  相似文献   
4.
5.
The influence of synthetic bradykinin (BK) on disturbed protein and carbohydrate metabolism was studied in chemical and manifest maturity-onset diabetics, in surgical patients and in alloxan diabetic rats. BK,mixed with insulin and injected subcutaneously twice daily in alloxan diabetic rats lowered the morning blood glucose concentration in a dose-dependent way, whereas in a control group treated with insulin only no decrease was seen. Accelerated local blood flow or enhanced vascular permeability as a cause of increased glucose uptake could be ruled out by control experiments using papaverine and eledoisin. Better metabolic control in the BK/insulin-treated group was also indicated by lower arterial levels of free fatty acids and of -hydroxybutyrate, normalized hepatic glycogen content and better growth of body weight. In healthy man an intravenous infusion of BK (80 g/h) did not influence normal fasting blood glucose concentrations, whereas elevated glucose levels in maturity-onset diabetics were continuously reduced within 100 min by 12.2±1.4%. A comparable diabetic group receiving saline alone showed no spontaneous drop of blood glucose concentration. An improvement of pathological carbohydrate metabolism by infusion of BK i.v. could also be demonstrated using the intravenous glucose tolerance test in chemical and manifest maturity-onset diabetics and in surgical patients: in all groupsk values of the glucose tolerance test were significantly increased by BK. This effect was neither due to stimulated insulin release nor to changed glucose pool or to increased renal glucose loss, which was even reduced by BK. Interestingly, normalk values in healthy volunteers were not further improved by BK. A stimulated protein breakdown, which occurs after surgery due to peripheral insulin resistance, can also be restricted by intravenous infusion of BK: in surgical patients urinary nitrogen excretion was reduced by 50% during infusion of BK and was accelerated again after cessation of the infusion. These results indicate that BK can improve the efficacy of exogenous insulin in insulin-deficient animals and depressed insulin sensitivity in maturity-onset diabetics and surgical patients.  相似文献   
6.
Summary The initial, site-specific colonization of secondary organs by blood-borne cancer cells appears to be mediated by endothelial cell adhesion molecules. These molecules are part of the organ-specific microvascular phenotype and are regulated through complex interactions of the endothelium with the extracellular matrix (e.g., distinct matrix macromolecules and growth factors). They are inducedin vitro by growing unspecific (large vessel) endothelial cells on extracts of organ-specific biomatrices. In many respects, these molecules are similar to the various classes of chemically different adhesion molecules that regulate lymphocyte traffic, but are believed to be distinct from the inducible adhesion molecules that govern leukocyte adhesion during acute episodes of inflammation. Biochemical and biophysical data indicate that preference of tumor cell adhesion to organ-specific microvascular endothelium may not require qualitative differences of such homing receptors between endothelia, but may be explained on the basis of quantitative receptor differences as well as differences of receptor avidity. Following adhesion, the metastatic cascade proceeds by the establishment of metabolic conduits between the endothelium and adherent tumor cells. This heterotypic coupling represents an early step in the extravasation of cancer cells from the microvasculature, initiating endothelial cell retraction from its basement membrane and recanalization around the arrested tumor cell. These events, together with local growth promoting effects exerted by the metastasized organ, are believed to provide the basis for Paget's seed and soil hypothesis of metastasis.  相似文献   
7.
Direct cardiac and vascular effects of the antikaliuretic diuretic potassium-canrenoate were measured in cardio-surgical patients during extracorporal circulation and immediatly after operations, each time in neuroleptanalgesia. During "steady state" extracorporeal circulation (aorta cross-clamped, constant flow rate of heart-lung-machine, constant hypothermia), in 13 patients no significant influence on peripheral circulation was found after i.v.-injection of 800 mg potassium-canrenoate. Neither arterial perfusion pressure (representing an arterial vascular reaction) nor changes in oxygenator-volume (indicating venous vasodilation or contraction) demonstrated significant differences in comparison to a control group. After cardiac surgery haemodynamic measurements were performed for a period of 60 minutes in 10 patients given 800 mg potassium-canrenoate. In comparison with a control group (n = 6), no significant differences in arterial pressure, heart rate, cardiac index and pulmonary arterial pressure were found. Left ventricular measurements, using a catheter tip manometer, revealed no direct positive inotropic effect of a single i.v.-injection of potassium-canrenoate. In acute myocardial failure during anaesthesia or in "low cardiac ouptut" following open heart surgery no improvement in myocardial contractility is obtained by i.v.-application of potassium-canrenoate; at the present there seems no alternative to other positive inotropic agents such as calcium, glucagon, dopamine, orciprenaline and epinephrine.  相似文献   
8.
BACKGROUND: Complete correction of atrioventricular septal defect (AVSD) associated with tetralogy of Fallot (TOF) has been reported to account for an increased surgical risk. Impaired right ventricular function after classic transventricular repair, residual outflow tract stenosis, and incompetence of the pulmonary or atrioventricular valves are considered to be essential factors affecting the results. METHODS: From 3/95 to 6/98 six consecutive patients with AVSD and TOF underwent repair (age 18 months to 7.3 years) using a combined transatrial-transpulmonary approach. RV outflow tract balloon dilatation preceded transatrial correction in 4 patients. Pulmonary annulotomy but not transanular patching was necessary in 4 cases. The septal defects were closed by two separate patches using a Dacron patch with short depth and anterior extension for the ventricular component. RESULTS: All patients survived and had stable sinus rhythm. Echocardiography demonstrated mild, but hemodynamically insignificant mitral regurgitation in two and tricuspid regurgitation in four patients. Right ventricle to pulmonary artery gradients ranged from 5 to 35 mmHg (mean 24.2 mmHg) without progression. During follow-up ranging from 4 months to 3.5 years (mean 16.8 months) no reoperation was necessary. CONCLUSIONS: The transatrial-transpulmonary approach for correction of AVSD with TOF contributes to improved results after repair of this rare combination of defects.  相似文献   
9.
Out of 887 consecutive patients who underwent aortic valve replacement between January 1976 and December 1981 at Hannover Medical School Hospital, 3 patients had severe aortic valve insufficiency associated with ankylosing spondylitis (Morbus Bechterew). One of them had huge aneurysmatic dilatation of the ascending aorta and successfully underwent replacement of the ascending aorta by a vascular prosthesis. Microscopical examination of the resected aortic wall showed characteristic findings of aortitis in ankylosing spondylitis. The 3 patients are in good clinical condition at 5 and 6 months, and 2 1/2 years, respectively, after uneventful surgery. It is concluded that aortic valve replacement in patients with ankylosing spondylitis can be performed feasibly and clinical results have been satisfactory. The risk of aneurysmatic dilatation of the ascending aorta resulting from aortitis associated with ankylosing spondylitis is emphasized.  相似文献   
10.
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