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   13922篇
  免费   721篇
  国内免费   95篇
耳鼻咽喉   89篇
儿科学   290篇
妇产科学   130篇
基础医学   2222篇
口腔科学   97篇
临床医学   1393篇
内科学   3125篇
皮肤病学   371篇
神经病学   1344篇
特种医学   590篇
外科学   2077篇
综合类   48篇
一般理论   2篇
预防医学   674篇
眼科学   227篇
药学   982篇
中国医学   42篇
肿瘤学   1035篇
  2023年   63篇
  2022年   91篇
  2021年   264篇
  2020年   159篇
  2019年   225篇
  2018年   325篇
  2017年   206篇
  2016年   238篇
  2015年   276篇
  2014年   381篇
  2013年   531篇
  2012年   929篇
  2011年   1054篇
  2010年   616篇
  2009年   546篇
  2008年   892篇
  2007年   1027篇
  2006年   923篇
  2005年   968篇
  2004年   893篇
  2003年   876篇
  2002年   851篇
  2001年   145篇
  2000年   128篇
  1999年   157篇
  1998年   218篇
  1997年   170篇
  1996年   172篇
  1995年   114篇
  1994年   113篇
  1993年   113篇
  1992年   105篇
  1991年   73篇
  1990年   57篇
  1989年   73篇
  1988年   69篇
  1987年   56篇
  1986年   56篇
  1985年   44篇
  1984年   55篇
  1983年   56篇
  1982年   46篇
  1981年   38篇
  1980年   44篇
  1979年   37篇
  1978年   29篇
  1977年   29篇
  1974年   34篇
  1973年   26篇
  1972年   26篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
BACKGROUND: Flap failure is a major complication in reconstructive plastic surgery. One of the most frequent etiologies of flap failure is venous thrombosis. However, infrequent causes also need to be explored, especially when faced with recurrent thrombosis. Heparin is frequently used in the prevention of venous thrombosis; however, the use of the medication itself may cause a serious thromboembolic state via an immune-related pathophysiological process. This adverse reaction to heparin may be life threatening. CASE PRESENTATION: We present two cases, one pedicled and one free flap, with venous congestion concomitant to heparin-induced thrombocytopenia syndrome, in conjunction with severe life-threatening sequelae. CONCLUSIONS: Heparin-induced thrombocytopenia syndrome can be the cause of postoperative venous congestion. It is necessary to be alert for this syndrome in the presence of recurrent unexplained venous thrombosis or thrombocytopenia in patients receiving anticoagulation therapy.  相似文献   
172.
A 21-year-old male patient presented with a typical middle aortic syndrome. Echography disclosed a severe narrowing of the lower thoracic aorta with parietal thickening. The isolated character of the lesion was confirmed by magnetic resonance imaging and aortography. The surgical cure was realized by a Dacron bypass between the upper thoracic descending aorta and the juxta-diaphragmatic thoracic aorta. Aortic biopsy confirmed Takayasu's disease. Postoperative course was uneventful with normalized blood pressure. The therapeutic options, surgery versus percutaneous dilatation and stent, are discussed.  相似文献   
173.
Since the beginning of shoulder arthroscopy, many different approaches were described for Bankart repair to allow visualization and treatment. The anterior portals do not allow access to the posterior and inferior part of the glenoid. We present a new instrumental portal for shoulder arthroscopy. This approach is perfectly safe, without any anatomic risk. It is particularly helpful in the correct treatment of an anterior Bankart lesion, in repairing posterior and inferior extensions of a Bankart lesion, and in performing a plication in multidirectional hyperlaxity.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 9 (November-December), 2001: pp 1000–1002  相似文献   
174.
Single‐lumen cannula venovenous (VV) extracorporeal membrane oxygenation (ECMO) is a special extracorporeal life support (ECLS) technique used for neonatal and pediatric refractory hypoxemia. This is an alternative flow rate ECLS that consists of successive clamping on the drainage and the injection lines. Currently, the Armand‐Trousseau's pediatric intensive care unit remains the only pediatric ECMO center proposing this partial assistance. This article details a technical note and a retrospective analysis of our experience in refractory hypoxemia. The retrospective study, from 2007 to 2011, included all pediatric and neonatal patients treated by single‐lumen cannula VV ECMO. The study was focused on pre‐ECMO patient characteristics and complications during ECMO course. During the last 5 years, 67 pediatric patients were assisted by this single‐lumen cannula VV ECMO. Sixty‐one patients (91%) were newborns. Thirty‐nine patients presented with meconium aspiration syndrome (58%), which was the most frequent etiology. Before cannulation, mean oxygenation index (OI) was 32 ± 11, alveolar‐arterial oxygen difference was 604 ± 47 mm Hg, and partial pressure arterial oxygen/fraction inspired oxygen ratio was 59.2 ± 35.8. Forty‐eight patients (72%) presented pulmonary hypertension, and 66 patients were treated by nitric oxide (98%). Fifty patients (75%) were treated by vasopressors or inotropic drugs. Average duration of ECMO was 13.2 ± 7.8 days. There were forty‐six survivors (69%). The worst prognosis was for respiratory syncytial virus pneumonia. Complications like acute renal injury and hematologic and transfusion acts were not so different than those observed in classical ECMO techniques. Nevertheless, 19 patients presented a stroke (28% of the overall population), but this high rate did not seem to be due to the ECLS technique used. Single‐lumen cannula VV ECMO is a partial and efficient ECMO support. Our experience shows that this technique is as efficient and less invasive than two cannulas ECMO. The single‐lumen cannula VV ECMO is a simple and safe ECLS support used for neonatal or pediatric refractory hypoxemia. Because this is a partial assistance, it is a promising ECLS support.  相似文献   
175.
In rare instances, tarsal coalition leads to cavovarus foot deformity, although the pathologic mechanism leading to this deformity is not clear. This article reports a case of a 14-year-old boy presenting a severe cavovarus deformity of the right foot with talocalcaneal and calcaneonavicular coalitions, and a mild cavus deformity of the left foot with a single talocalcaneal coalition. Computed tomography and postoperative histologic analysis demonstrated a synostosis between talus and calcaneus and a fibrous calcaneonavicular coalition with partial ossification. Instrumented gait analysis revealed a limited range of ankle plantar flexion and increased external rotation of the ankle. Associated skeletal malformations including incomplete hemimelia of the forearm and scoliosis raised the possibility of a teratologic condition, but neurologic examination, spinal magnetic resonance imaging, and nerve conduction velocities were normal. The progressive ossification of combined coalitions during growth of the foot may have been one factor leading to this complex foot deformity. The fine-wire electromyogram showed normal tibialis anterior and posterior muscle activity. Small soft tissue tears in the sinus tarsi may have led to a mild reflexive increase of the muscle tone and tendon shortening, which pulled the forefoot into adduction and the heel into varus, and raised the medial arch. Mechanical alterations of the ankle appear secondary to the heel varus and to the progressive deformity of the talus. Three-dimensional computed tomography reconstruction and gait analysis appeared to be helpful additional parameters to understanding the pathomechanics of this complex foot deformity and for preoperative planning of triple arthrodesis.  相似文献   
176.
177.
OBJECTIVE: Dilation of aortic annulus, sinuses of Valsalva, and sinotubular junction (STJ) diameters are the characteristic lesions of aortic root aneurysm. The remodeling technique reduces STJ diameter and creates three neosinuses of Valsalva. Alternatively, the reimplantation technique reduces both annulus and STJ diameters to the detriment of aortic root dynamics. Although the remodeling technique is recognized as the most physiological valve-sparing procedure, aortic annulus dilation may jeopardize its results. A standardized approach that combines an external subvalvular aortic prosthetic ring annuloplasty with the remodeling technique is suggested. METHODS: Eighty-three patients underwent an elective aortic root remodeling procedure, either isolated (group 1, n=34) or combined with an external subvalvular aortic prosthetic ring annuloplasty (group 2, n=49). Preoperative aortic regurgitation was 1.59+/-1.1 (group 1) and 1.97+/-1.3 (group 2) (NS). The aortic annulus was more dilated in group 2 than in group 1 (27+/-2.77 mm vs 26.4+/-2.3 mm, p<0.01). Residual aortic regurgitation > or =grade II was the conversion criteria for aortic valve replacement. RESULTS: Operative mortality was 3.6% (n=3). Intraoperative conversion for valve replacement was 32.7% in group 1 (n=11) versus 4.2% in group 2 (n=2) (p<0.001). In group 1, preoperative annulus diameter was larger for converted than for valve-spared patients (27.6+/-1.7 mm vs 25.2+/-1.5 mm, p<0.02). In group 2, implanted aortic ring significantly reduced annulus diameter (20.6+/-1.8 mm) without significant aortic valve gradient (8.3+/-3 mmHg). Follow-up was 17.2+/-13.4 months (group 1) and 10.41+/-7.95 months (group 2). Reoperation for recurrent aortic regurgitation was 13% in group 1 (n=3) versus 4.2% in group 2 (n=2). Echocardiographic follow-up found residual aortic regurgitation < or =grade I in 17 patients in group 1 (90%) versus 43 patients in group 2 (95.5%) and of grade II in two patients in group 1 (10%) and two patients in group 2 (4.5%). CONCLUSION: The addition of external aortic prosthetic ring annuloplasty improves the remodeling technique's operative reproducibility and short-term results. Therefore, its use as a systematical adjunct to the remodeling procedure is suggested. However, further long-term evaluation comparing this valve-sparing procedure to composite graft replacement should define the best surgical strategy for aortic root aneurysm.  相似文献   
178.
Out of 210 children suffering from severely displaced supracondylar fractures, 76 (36%) presented with immediate neurovascular complications: 47 (22%) were neurological, 16 (8%) vascular and 13 (6%) both. Injury to two nerves simultaneously was observed in six patients. The median nerve was affected in 28 cases, the ulnar nerve in 25 and the radial nerve in 13. Posterolateral displacement was associated with 86% of damage to the median nerve and 56% of damage to the ulnar nerve. Posteromedial displacement was associated with all incidents of injury to the radial nerve with one exception. Each patient made full neurological recovery, spontaneously and following primary or secondary neurolysis performed on nerve injuries in continuity. Two situations of primary abolition of the radial pulse were encountered, one involving a pink hand in 12.5% of cases and the other involving a white hand in 1.5% of cases. There was posterolateral displacement in three out of four patients. Postoperative vascularization was revealed by immediate return of the radial pulse in 26 patients and delayed return in three others. Urgent anatomical reduction of the fracture and its early fixation are crucial. A conservative therapeutic approach is customary in the majority of neurovascular complications. Prognosis is generally excellent. Ischaemia of the limb and total ruptures of the nerve are very rare.  相似文献   
179.
A major risk associated with bupivacaine during myocardial ischemia is ventricular fibrillation. We investigated the influence of ropivacaine on cardiac contractility and the propensity to ventricular fibrillation before and after myocardial ischemia in a placebo-controlled pig study. Anesthetized domestic pigs were administered 1 mg·kg−1 of ropivacaine intravenously over 1 min and then 0.03 mg·kg−1·min−1 as a 30-min infusion, or saline. The following endpoints were measured before and after ropivacaine administration: (1) the ventricular fibrillation threshold (VFT) before and during myocardial ischemia induced by total transient ligation of the anterior interventricular artery and (2) electrophysiological (sinus heart rate, duration of QRS and QT intervals) and hemodynamic (blood pressure, the time derivative of left ventricular pressure [peak LV dP/dt]) parameters. Ropivacaine induced no changes in sinus heart rate, QRS, and or QT before or during ischemia. In contrast, there was a mild increase in the VFT before ischemia, which was drastically and significantly reduced during ischemia. The reduction of peak LV dP/dt during ischemia was further increased by ropivacaine. We also found that the effect of ropivacaine on the VFT was coronary blood flow-dependent, with a markedly decreased threshold in the presence of ischemia. Similar effects have been observed in humans with several other local anesthetics, as well as with class I antiarrhythmic drugs. The results of this study should be taken into account by anesthesiologists when administering ropivacaine to coronary patients.  相似文献   
180.
BACKGROUND: No study on bioclinical criteria predicting a biliary origin for acute pancreatitis has included endosonography as a reference examination. Re-examination of bioclinical parameters deserves consideration in the era where other causes are known (e.g. hereditary, autoimmune). AIM AND METHODS: To determine the performance of bioclinical markers in predicting a biliary origin of acute pancreatitis where the diagnosis of biliary lithiasis was established or ruled out using endosonography. Only patients with a first acute episode of pancreatitis were included. RESULTS: 213 patients (male: 55%; median age: 56 years) were prospectively included in 14 centres. Causes of acute pancreatitis were: biliary (62%), alcoholic (25%), other (13%). Delay between symptom-onset and admission was <48 h in 80%. Endosonography was the sole method establishing the diagnosis of biliary pancreatitis in 15% of patients. At univariate analysis, age, female sex, declared alcohol consumption, elevated aspartate and alanine transaminases on admission, gammaglutamyl transferase, alkaline phosphatase, total bilirubin, lipase, mean corpuscular volume were predictive of a biliary origin. Only age (p < 0.0001), sex (p < 0.0008) and alanine transaminase (p < 0.0004) remained significant at multivariate analysis. At age 50, the respective sensitivity and specificity were 73 and 65%. With an elevated alanine transaminase at 2 times the upper limit of normal range, the respective sensitivity and specificity were 74 and 84%. The probability of a biliary origin of acute pancreatitis could be estimated by the following formula: = 1/1 + exp(4.6967 - 0.0656 x age + 1.1208 x sex - 0.6909 x alanine transaminase). CONCLUSION: When endosonography is performed to confirm or exclude a biliary origin of acute pancreatitis, age, sex and alanine transaminase at admission are the only factors predictive of a biliary cause.  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