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   1294篇
  免费   59篇
  国内免费   2篇
耳鼻咽喉   11篇
儿科学   42篇
妇产科学   15篇
基础医学   139篇
口腔科学   16篇
临床医学   100篇
内科学   238篇
皮肤病学   26篇
神经病学   262篇
特种医学   45篇
外科学   227篇
综合类   10篇
预防医学   89篇
眼科学   9篇
药学   85篇
中国医学   1篇
肿瘤学   40篇
  2024年   3篇
  2023年   8篇
  2022年   17篇
  2021年   25篇
  2020年   16篇
  2019年   32篇
  2018年   35篇
  2017年   27篇
  2016年   33篇
  2015年   31篇
  2014年   37篇
  2013年   35篇
  2012年   86篇
  2011年   81篇
  2010年   46篇
  2009年   40篇
  2008年   54篇
  2007年   54篇
  2006年   66篇
  2005年   55篇
  2004年   49篇
  2003年   57篇
  2002年   68篇
  2001年   37篇
  2000年   54篇
  1999年   44篇
  1998年   17篇
  1997年   14篇
  1996年   7篇
  1995年   8篇
  1994年   9篇
  1993年   10篇
  1992年   21篇
  1991年   22篇
  1990年   20篇
  1989年   21篇
  1988年   16篇
  1987年   15篇
  1986年   11篇
  1985年   16篇
  1984年   5篇
  1983年   3篇
  1982年   5篇
  1981年   3篇
  1980年   3篇
  1979年   5篇
  1978年   7篇
  1976年   6篇
  1975年   3篇
  1974年   3篇
排序方式: 共有1355条查询结果,搜索用时 15 毫秒
101.
102.
OBJECTIVE: The aim of this study was to investigate the transtympanic ventilation time, the healing course of the tympanic membrane, the early and late complications, and the recurrence rate of otitis media with effusion (OME) within 6 months after CO2 laser myringotomy with the CO2 laser otoscope Otoscan. STUDY DESIGN: Prospective clinical study. MATERIALS AND METHODS: In this study, laser myringotomy was performed with the CO2 laser otoscope Otoscan in a patient population comprising 81 children (159 ears) with a history of otitis media with effusion (OME) associated with adenoidal and sometimes tonsillar hyperplasia. The procedure on the tympanic membrane was accordingly combined with an adenoidectomy, a CO2 laser tonsillotomy, or a tonsillectomy and therefore performed under insufflation anesthesia. In all ears, approximately 2 mm circular perforations were created in the lower anterior quadrants with a power of 12 to 15 W, a pulse duration of 180 msec, and a scanned area of 2.2 mm in diameter. RESULTS: None of the children showed postoperative impairment of cochleovestibular function such as sensorineural hearing loss or nystagmus. Otomicroscopic and videoendoscopic monitoring documented the closure time and healing pattern of tympanic membrane perforations. The mean closure time was found to be 16.35 days (minimum, 8 days; maximum, 34 days). As a rule, an onion-skin-like membrane of keratinized material was seen in the former myringotomy perforations at the time of closure. At the follow-up 6 months later, the condition of the tympanic membrane of 129 ears (81.1%) could be checked by otomicroscopy and videoendoscopy and the hearing ability by audiometry and tympanometry. The CO2 laser myringotomy sites appeared normal and irritation-free. Two of the tympanic membranes examined (1.6%) showed atrophic scar formation, and 1 (0.8%) had a perforation with a diameter of 0.3 mm. The perforation was seen closed in a control otoscopy 15 months postoperatively. OME recurred in 26.3% of the ears seen intraoperatively with mucous secretion (n = 38) and in 13.5% of the ears with serous secretion (n = 37; P <.05). CONCLUSION: The most important principle in treating OME is ventilation of the tympanic cavity. CO2 laser myringotomy achieves this through a self-healing perforation in which its diameter roughly determines the duration of transtympanic ventilation. Laser myringotomy competes with ventilation tube insertion in the treatment of OME. It may be a useful alternative in the surgical management of secretory otitis media.  相似文献   
103.
Hypomagnesemia after aneurysmal subarachnoid hemorrhage   总被引:10,自引:0,他引:10  
van den Bergh WM  Algra A  van der Sprenkel JW  Tulleken CA  Rinkel GJ 《Neurosurgery》2003,52(2):276-81; discussion 281-2
OBJECTIVE: Hypomagnesemia frequently occurs in hospitalized patients, and it is associated with poor outcome. We assessed the frequency and time distribution of hypomagnesemia after aneurysmal subarachnoid hemorrhage (SAH) and its relationship to the severity of SAH, delayed cerebral ischemia (DCI), and outcome after 3 months. METHODS: Serum magnesium was measured in 107 consecutive patients admitted within 48 hours after SAH. Hypomagnesemia (serum magnesium <0.70 mmol/L) at admission was related to clinical and initial computed tomographic characteristics by means of the Mann-Whitney U test. Hypomagnesemia at admission and during the DCI onset period (Days 2-12) was related to the occurrence of DCI and hypomagnesemia at admission, and hypomagnesemia that occurred any time during the first 3 weeks after SAH was related to outcome. RESULTS: Hypomagnesemia at admission was found in 41 patients (38%) and was associated with more cisternal (P = 0.006) and ventricular (P = 0.005) blood, a longer duration of unconsciousness (P = 0.007), and a worse World Federation of Neurosurgical Societies scale score at admission (P = 0.001). The crude hazard ratio for DCI with hypomagnesemia at admission was 2.4 (95% confidence interval, 1.0-5.6), and after multivariate adjustment it was 1.9 (95% confidence interval, 0.7-4.7). The hazard ratio of hypomagnesemia from Days 2 to 12 for patients with DCI was 3.2 (range, 1.1-8.9) after multivariate adjustment. The crude odds ratio for poor outcome (Glasgow Outcome Scale score, 1-3) with hypomagnesemia at admission was 2.5 (range, 1.1-5.5). Hypomagnesemia at admission did not contribute to the prediction of outcome in the multivariate model. CONCLUSION: Hypomagnesemia is frequently present after SAH and is associated with severity of SAH. Hypomagnesemia occurring between Days 2 and 12 after SAH predicts DCI.  相似文献   
104.
Bilateral rupture of the patellar tendons is a rare lesion, usually associated with systemic diseases such as systemic lupus erythematosus, rheumatoid arthritis, chronic renal failure and others. It is extremely rare in a healthy individual, with fewer than 15 cases described. A case of a 32-year-old male with no known history of systemic disease or knee problems is presented. Physical examination, xrays and MRI demonstrated bilateral rupture of the patellar tendons. The tendons were repaired using a nonabsorbable suture reinforced with two titanium anchors fixed to each patella, and a quadriceps tendon flap. The evolution was satisfactory, with both knees recovering a full range of motion in a four-month period.  相似文献   
105.
Four new compounds, a sesquiterpene, eleganodiol (1), and three sesquiterpene lactones, eleganolactone A (2), eleganolactone B (3), and elegain (4), were isolated from Gonospermum elegans along with 16 known compounds. The structures of 1, 2, and 4 were determined on the basis of MS and NMR studies of their acetate derivatives (1a, 2a, 4a). The structure of the acetate derivative (3a) of 3 was determined on the basis of spectroscopic data interpretation and by single-crystal X-ray diffraction. Compounds 2a and 3a were used to study their biological activities on the HL-60 human promyelocytic leukemia cell line. These compounds induced morphological changes and internucleosomal DNA fragmentation characteristic of apoptotic cell death.  相似文献   
106.
Background and Purpose: Subarachnoid haemorrhage is a common cause of death in patients with autosomal dominant polycystic kidney disease (ADPKD), but little is known about specific characteristics of subarachnoid haemorrhage and intracranial aneurysms in this group of patients. We performed a systematic review on site, size and number of aneurysms, age at time of rupture, gender, and family history in patients with ADPKD and intracranial aneurysms. We also studied the frequency of ADPKD in patients with subarachnoid haemorrhage treated in our hospital. Methods: We performed a MEDLINE search and checked the reference lists of all relevant publications to identify all articles published from 1980 to 2000 on intracranial aneurysms or subarachnoid haemorrhage in ADPKD. We studied our database of patients with subarachnoid haemorrhage treated between 1978 and 1999 for the presence of ADPKD. Results: We included 53 articles on 369 ADPKD patients (139 [54 %] women) with 462 intracranial aneurysms. Of the 273 aneurysms with specified locations 105 (38 %) were located on the middle cerebral artery in and on the anterior communicating artery in 83 patients (30 %). In 253 patients with data about relatives, the family history was positive for intracranial aneurysms or subarachnoid haemorrhage in 102 (40 %). The average age at which subarachnoid haemorrhage had occurred in 258 was 41 years; of 158 in whom the gender was given; 96 (52 %) were women. Of the 160 patients with data on outcome, 69 (43 %) had died as the result of the subarachnoid haemorrhage. Of the 1147 patients treated for aneurysmal subarachnoid haemorrhage in our institution (mean age 53 years; 65.5 % women), 5 (0.44 %) had ADPKD. Conclusions: Compared with data on patients without ADPKD, subarachnoid haemorrhage in patients with ADPKD occurs not only often in a familial setting of subarachnoid haemorrhage, but also at an earlier age and more often in men. In patients with ADPKD, the most frequent site of aneurysms is the middle cerebral artery. The proportion of patients with ADPKD among all patients with subarachnoid haemorrhage is very small. Received: 17 April 2002, Received in revised form: 11 October 2002, Accepted: 16 October 2002 Correspondence to Professor Gabriel J. E. Rinkel  相似文献   
107.
Polymethylmethacrylate (PMMA) bone cement is a biomaterial used to anchor prostheses during joint replacement surgery. Residual methylmethacrylate monomer (MMA) may be related with the cytotoxic effect of PMMA. The aim of the present paper was to investigate the effect of two different cement mixing methods: hand stirring at atmospheric pressure and under partial vacuum (0.330 and 0.154 bar) on residual monomer liberation in phosphate buffer saline solution from acrylic cement powder. Residual MMA content was determined by high-performance liquid chromatography. Mathematical models were applied to experimental dissolution data revealing that monomer release was significantly reduced in bone cement powder obtained at 0.154 bar vacuum pressure compared to the other mixing conditions. The kinetic models applied are consistent with a simple diffusion mechanism of the monomer from the polymer matrix.  相似文献   
108.
We observed the effects of sodium bicarbonate supplement on bone mass in rats on strenuous treadmill training. Sixty female Wistar rats (93-days-old; mean initial weight 261 ± 16 g) were studied. One group of 15 rats was killed at the beginning of the experiments (basal control group), while another group of 15 rats was not manipulated (Exer−NaB−). Another group of 15 rats was exercised but did not receive sodium bicarbonate (Exer+NaB−), while the final group of 15 rats exercised and received sodium bicarbonate (Exer+NaB+) at a dose of 0.05 mg/kg/day, administered by esophageal catheter on exercise days. These rats were killed at the end of 11 weeks. Femoral and vertebral length, weight, and bone mineral content (BMC) and density (BMD) were measured. According to anova with the Tukey–Kramer test, femur length and weight, vertebral weight, femur BMC and BMD, vertebral BMC and BMD and the ratio between femur and vertebral BMC and final body weight, and plasma bicarbonate were lower in the basal control and Exer+NaB− groups than in the two other groups (P < 0.005–0.0001). Overall, there was a positive correlation between femur and vertebral BMC and femur BMC and length (P < 0.0001 for all). Only in the Exer+NaB− group was there a positive association between plasma bicarbonate levels and femur length (r = 0.78; P < 0.0005). Our study demonstrates the adverse effects of strenuous exercise on bone, and the usefulness of sodium bicarbonate supplements in preventing and minimized these effects. Received: May 1, 2000 / Accepted: August 11, 2000  相似文献   
109.
We describe the clinical presentation, radiological and clinical results in six consecutive patients with a giant vertebrobasilar aneurysm treated by bilateral vertebral artery balloon occlusion. Five patients presented with headache and signs of brain-stem compression and one with subarachnoid haemorrhage. In all patients vertebral artery balloon occlusion was performed. In four, this followed successful test occlusion. In one patient, who did not tolerate the test occlusion, a bypass from the external carotid to the posterior cerebral artery preceded definitive vertebral artery occlusion. One patient underwent bypass surgery prior to test occlusion. At 6–22 months follow-up three patients had a good functional outcome and showed unchanged size or shrinkage of the aneurysm on MRI. Three other patients died; one from recurrent haemorrhage, and two probably from delayed brain-stem ischaemia. The presence of two large posterior communicating arteries predicted good functional outcome, which was also related to the clinical condition at presentation, and the degree of brain-stem compression and oedema on MRI. Bilateral vertebral artery balloon occlusion can be considered in patients with otherwise untreatable giant vertebrobasilar aneurysms. If test occlusion is not tolerated, a surgical bypass to the posterior circulation can be considered. Received: 1 December 1999 Accepted: 6 October 2000  相似文献   
110.
The ectopic pregnancy appears in the 10-12% of cases after tubal sterilization and it is usually located in the tube. 1% of ectopic pregnancies are abdominal and the implantation in omentum is a rare condition with only 16 described cases. According to Studdiford, they can be classified as primary or secondary depending on whether they are originated or not in the peritoneal cavity. We present the case of a secondary abdominal pregnancy located in omentum, in a woman with previous tubal sterilization, which has not been described to date; one is an abdominal pregnancy with origin in a tubal abortion, since trofoblastic invasion does not exist in omentum and there are remains of the same tissue in the right tube.  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