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   9605篇
  免费   468篇
  国内免费   57篇
耳鼻咽喉   117篇
儿科学   131篇
妇产科学   117篇
基础医学   1081篇
口腔科学   168篇
临床医学   610篇
内科学   2535篇
皮肤病学   93篇
神经病学   600篇
特种医学   430篇
外科学   2056篇
综合类   44篇
预防医学   192篇
眼科学   79篇
药学   765篇
中国医学   25篇
肿瘤学   1087篇
  2023年   72篇
  2022年   134篇
  2021年   243篇
  2020年   113篇
  2019年   181篇
  2018年   213篇
  2017年   206篇
  2016年   222篇
  2015年   208篇
  2014年   281篇
  2013年   365篇
  2012年   508篇
  2011年   607篇
  2010年   325篇
  2009年   300篇
  2008年   507篇
  2007年   565篇
  2006年   586篇
  2005年   567篇
  2004年   617篇
  2003年   588篇
  2002年   576篇
  2001年   199篇
  2000年   211篇
  1999年   223篇
  1998年   124篇
  1997年   118篇
  1996年   96篇
  1995年   86篇
  1994年   81篇
  1993年   68篇
  1992年   96篇
  1991年   87篇
  1990年   77篇
  1989年   77篇
  1988年   70篇
  1987年   92篇
  1986年   64篇
  1985年   68篇
  1984年   36篇
  1983年   39篇
  1982年   21篇
  1981年   16篇
  1980年   14篇
  1979年   19篇
  1978年   22篇
  1977年   28篇
  1976年   15篇
  1975年   15篇
  1974年   24篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by 123I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome.  相似文献   
52.
Thrombocytopenia is a frequent finding following living donor hepatectomy. It appears more pronounced in right graft donors than in left graft donors. This study analyzed postoperative thrombocytopenia in 20 living liver donors and examined the change of endogenous thrombopoietin (TPO) in its recovery. Platelet count, TPO level, fibrinogen degradation product (FDP), and D-Dimer were measured before surgery and on postoperative days (PODs) 1, 2, 3, 5, 7, and 14. Concurrently, liver and spleen volumes were calculated by computed tomography. Platelet count on POD 3 was significantly lower in right graft donors than in left graft donors (13.0 +/- 3.7 x 10(4)/microL vs. 16.8 +/- 4.0 x 10(4)/microL, P = 0.039) but recovered by POD 7 in all donors. Postoperative elevations of FDP and D-Dimer were significantly higher in right graft donors than in left graft donors. TPO level rose immediately after surgery, peaked on POD 5 in left graft donors and on POD 7 in right graft donors, and fell nearly to preoperative levels by POD 14. Postoperative TPO level per liver volume was significantly higher in right graft donors than in left graft donors. In conclusion, thrombocytopenia following living donor hepatectomy resolved within the first week regardless of graft type and was mainly associated with increasing consumption of circulating platelets, possibly due to intrahepatic and splenic congestion. With a reduced number of circulating platelets, TPO level rapidly increases. Also, with reduced consumption of platelets related to recovery from surgery, thrombocytopenia should resolve. As a consequence, TPO level would be expected to fall.  相似文献   
53.
54.
An 80-year-old man underwent middle and lower lobectomy of the right lung to treat squamous cell carcinoma (SCC) (4 cm in diameter) originating from the right B4 bronchus. On the 4th postoperative day, a massive air leak from the thoracic drain was noted. At that time, a diagnosis of bronchial stump fistula was made on the basis of the bronchoscopic findings. Continuous thoracic drainage, aspiration of sputum via a tracheostomy and intravenous administration of antibiotics were performed immediately after the diagnosis. However, the patient's condition was complicated by aspiration pneumonia. On the 11th postoperative day, bronchoscopic procedure to close the bronchial fistula was performed via the tracheostomy. During this procedure, metallic coils were first inserted into the fistula to serve as the core for occlusion. Then, instead of directly infusing fibrin glue, several small beans-sized pieces of Surgicell cotton (Johnson & Johnson Co., Cincinnati, OH) soaked in fluid A (concentrated fibrinogen) and the same number of Surgicell cotton pieces soaked in fluid B (thrombin) were alternately inserted into the fistula, to allow closure of the bronchial fistula. After this procedure, the embolus created remained in place without being expectorated, and the aspiration pneumonia entered remission, allowing the patient to be discharged from the hospital on the 24th postoperative day. At preset, 14 months after surgery, the patient is in good condition. This technique allows simple and reliable closure of a fistula if a tracheostomy is available. It should be selected as a therapy of first choice when dealing with patients with a postoperative bronchial stump fistula in poor general condition. Patients undergoing right pneumonectomy or middle and lower lobectomy of the right lung should be considered as belonging to a high risk group for bronchial fistula and as requiring preventable measures (e.g., covering the stump with an intercostal muscle flap).  相似文献   
55.
OBJECTIVE: The risk of stroke caused by dislodgment of loose atheromatous plaque or mural emboli is increased by cross-clamping of the aorta. Some patients undergo descending thoracic aortic aneurysm repair with proximal aortic cross-clamping between the left common carotid artery and the left subclavian artery. The objective of this study was to determine the influence of proximal aortic cross-clamping in arteriosclerotic aneurysm or dissecting aneurysm repair. METHODS: Between May 1984 and May 2003, 81 patients underwent elective surgery for distal arch or descending aortic aneurysm repair with proximal aortic cross-clamping between the left common carotid artery and the left subclavian artery. To evaluate the influence of the proximal aortic cross-clamping, patients were divided into two groups: patients who had undergone arteriosclerotic aneurysm repair (group I, n=25) and patients who had undergone dissecting aneurysm repair (group II, n=56). RESULTS: Eight (9.9%) of the 81 patients had a stroke. Six strokes occurred in operations for arteriosclerotic aneurysm repair group I and two strokes occurred in operations for dissecting aneurysm repair group II (24 vs 3.6%; p=0.009). In-hospital mortality rates were 12% in group I and 8.9% in group II (p=0.70). Major postoperative complications included renal failure requiring hemodialysis (in 4.2% of the patients in group I and in 8.3% of the patients in group II, p=0.99) and pulmonary complication (in 20% of the patients in group I and in 16% of the patients in group II, p=0.67). CONCLUSION: Cross-clamping between head vessels should be avoided if at all possible when operating on patients who have arteriosclerotic descending thoracic aneurysms.  相似文献   
56.
Summary: Purpose: We wished to assess the risk of terato-genicity of zonisamide (ZNS) in humans.
Methods: Pregnant epileptic women treated with ZNS and their offspring were prospectively monitored from June 1989 to December 1994. The outcome of pregnancy and status of neonates were examined based on the same standardized protocol.
Results: Twenty-six offspring exposed to ZNS with or without other antiepileptic drugs (AEDs) were studied. Malformations were detected in 2 offspring (7·7%) exposed to ZNS polypharmacy. Anencephaly was detected in one case at 16 weeks of gestation (case 1, artificial abortion), and atrial septa1 defect was detected in another case at 37 weeks of gestation (case 2, delivery by cesarean section). Serum concentrations of ZNS during the first trimester of pregnancy were 6·1 μg/ml in case 1 and 6·3μ/ml in case 2; in both cases, the levels were below the therapeutic concentration range of ZNS.
Conclusions: Teratogenic effects of ZNS were not clearly defined from these results since malformations were detected in two polypharmacy cases but not in four monopharmacy cases. The present data do not indicate that the risk of ZNS teratogenicity is greater than that of other conventional AEDs. However, such risk cannot be neglected even at therapeutic dosages or concentrations of ZNS, especially in patients receiving polypharmacy.  相似文献   
57.
Pulmonary aspergillosis associated with old tuberculosis is generally resistant to treatment. Thus, if patients are treated only with conservative therapy, their condition continues to deteriorate due to repetitive hemoptysis, and may even become critical. Surgical treatment is required for these patients; however, it is extremely difficult to resect the lesion due to severe adhesions to the chest wall and vascular proliferation surrounding the lesion. We performed preoperative arterial embolization, achieving good results in three patients with hemoptysis caused by pulmonary aspergillosis. The feeding arteries were embolized using microcoils and/or gelatin sponges, and a lobectomy was safely carried out in all patients. We concluded that preoperative arterial embolization is a safe and effective technique to prevent massive hemorrhage occurring at the time of surgery. This work was presented at the 11th Annual Meeting of the Japanese Association for Chest Surgery, held in Kyoto, Japan, May 13–14, 1994  相似文献   
58.
59.
Abstract: We have used heparin-bonded partial cardio-pulmonary bypass to support distal aortic circulation during aortic cross-clamping. However, there were no cardiotomy reservoirs with fully reliable thromboresistance. To resolve this problem, a short-acting anticoagulant (nafamostat mesilate) was added into a cardiotomy reservoir. The present study was designed to evaluate the efficacy of our distal perfusion system. From May 1995 through the end of May 1996, 27 patients underwent descending thoracic and thoracoabdominal aortic aneurysm repairs with this adjunct, 4 being excluded from the experiment. Twenty patients who had undergone conventional partial cardiopulmonary bypass were defined as the control group. There were no significant differences between the 2 groups in the morbidity, mortality, gas transfer, or transfusion requirements despite the fact that more complicated surgical procedures (shown by a two-fold increase in the prevalence of reoperation) were required in the group that had received the current distal perfusion adjunct. the heparin-bonded group. In conclusion, our perfusion system is very effective for descending thoracic and thoracoabdominal aortic aneurysm repairs.  相似文献   
60.
Background. [123I]Metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. We evaluated the clinical significance of myocardial MIBG imaging as a measure of cardiac sympathetic nervous system function by comparing it to heart rate variability and plasma norepinephrine level.Methods and Results. In 211 subjects, we analyzed heart rate variability with 24-hour electrocardiography, performed scintigraphy with MIBG, and measured plasma norepinephrine levels. Time and frequency domain measures of heart rate variability were calculated with the Marquette heart rate variability program (Marquette Electronics, Milwaukee, Wis.). Early and late myocardial MIBG uptakes were measured at 15 and 150 minutes after injection, respectively. MIBG clearance rate from the heart and heart-to-lung and heart-to-mediastinum ratios of MIBG activities were calculated. On the whole, heart rate variability, including low-frequency power, correlated positively, but modestly so, with late MIBG uptake and negatively with MIBG clearance rate. The plasma norepinephrine level correlated negatively with late MIBG uptake and with heart rate variability, including low-frequency power, and positively with MIBG clearance rate. Similar correlations were also observed in patient subgroups with coronary artery disease, diabetes mellitus, and renal failure, but these correlations were weak (R2 < 0.5).Conclusions. Increased cardiac sympathetic nervous system activity may be associated with increased myocardial MIBG clearance and decreased heart rate variability, including low-frequency power. Because these associations were not strong, however, the combination of heart rate variability with MIBG may allow an interactive assessment of the cardiac autonomic nervous system.  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