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   747414篇
  免费   52650篇
  国内免费   1547篇
耳鼻咽喉   9548篇
儿科学   24509篇
妇产科学   18762篇
基础医学   116059篇
口腔科学   20849篇
临床医学   68000篇
内科学   143528篇
皮肤病学   17011篇
神经病学   54045篇
特种医学   27185篇
外国民族医学   76篇
外科学   110207篇
综合类   14979篇
现状与发展   2篇
一般理论   178篇
预防医学   54486篇
眼科学   17037篇
药学   56591篇
  3篇
中国医学   2437篇
肿瘤学   46119篇
  2021年   7135篇
  2019年   6856篇
  2018年   9486篇
  2017年   7251篇
  2016年   8099篇
  2015年   9040篇
  2014年   12313篇
  2013年   17938篇
  2012年   24274篇
  2011年   25253篇
  2010年   14608篇
  2009年   13710篇
  2008年   23006篇
  2007年   24396篇
  2006年   24512篇
  2005年   23030篇
  2004年   22149篇
  2003年   20896篇
  2002年   20174篇
  2001年   36547篇
  2000年   37045篇
  1999年   30600篇
  1998年   8166篇
  1997年   6879篇
  1996年   7166篇
  1995年   6804篇
  1994年   6250篇
  1992年   23052篇
  1991年   22999篇
  1990年   22370篇
  1989年   22116篇
  1988年   20074篇
  1987年   19450篇
  1986年   18497篇
  1985年   17336篇
  1984年   12736篇
  1983年   10760篇
  1982年   5960篇
  1979年   11527篇
  1978年   8140篇
  1977年   6844篇
  1976年   6601篇
  1975年   7272篇
  1974年   8502篇
  1973年   8144篇
  1972年   7666篇
  1971年   7130篇
  1970年   6878篇
  1969年   6310篇
  1968年   5783篇
排序方式: 共有10000条查询结果,搜索用时 742 毫秒
941.
942.
943.
A non-dilatable benign stricture of the esophagus is a problem for the patient and always a challenge for the surgeon. The present study is intended to provide some details of surgical technique and the physiological concept that constitutes the basis for patient selection for short-segment jejunoplasty. In this study, out of 98 patients, 91 had complex stricture of the lower, and seven of the cervical esophagus. The main cause of stenosis in 60 patients (61.2%) was gastroesophageal reflux, in 34 (34.7%) post-corrosive damage, and in three (3.0%) it was other causes. All patients were treated by three methods of jejunoplasty: group I (n=54 patients) short-segment of the jejunum; group II (n=37 pts) Roux-en-Y double tract; and group III (n=7 patients) short jejunal segment on the long vascular pedicle. Intraoperative complications occurred in 17 (17.34%) of the patients. An anastomotic leak occurred only in three (3.29%) in group I and II, and 1/98 patients (1.02%) died from mediastinitis. Follow-up of functional results for up to 36 months (average 18 months) was available in 77/97 (79.3%) hospital survivors. Fifty-seven (74%) patients are satisfied with their ability to take food, postoperative reflux was completely denied by 72 (93.5%) patients. Postvagotomy diarrhea was transient and gradually subsided over the course of the first 6 months.  相似文献   
944.
Two cases of internal herniation through a defect in the broad ligament of the uterus are described. Both were successfully treated laparoscopically. This rare condition should be borne in mind when a middle-aged woman presents with colicky lower abdominal pain. The cause is unknown, but both congenital and acquired origins have been proposed. As far as emergency situations are concerned, laparoscopy has proven to be both a diagnostic and a therapeutic tool.  相似文献   
945.
The immunologic risk associated with donor-specific antibodies (DSA) against Class II human leukocyte antigens (HLA) in kidney transplant (KTx) recipients is unclear. The aim of this study was to determine the outcome of KTx when DSA was detected only against HLA Class II. To isolate the impact of anti-Class II DSA, we retrospectively analyzed 12 KTx recipients who at baseline had a positive B-cell flow cytometric crossmatch (FXM) and a negative T-cell FXM. Using alloantibody specification analysis, 58.3% (7/12) had DSA against donor Class II and 41.7% had no demonstrable DSA. Biopsy-proven AMR occurred in 57% (4/7) in the Class II(+) group and 0% in the Class II(-) group (p > 0.05). Peritubular capillaries stained positive for C4d in 86% (6/7) of the Class II(+) patients and in 40% (2/5) of the Class II(-) patients (p > 0.05). One patient in the Class II(+) group lost their graft at 3 months to accelerated transplant glomerulopathy, while all other grafts were functioning 3-37 months posttransplant despite the persistence of anti-Class II DSA. We conclude that KTx recipients with clearly defined anti-Class II DSA are at risk for humoral rejection suggesting that desensitization and/or close posttransplant monitoring may be needed to prevent AMR.  相似文献   
946.
947.
Cerebellar involvement in motor and non-motor sequence learning was examined with serial reaction time tasks (SRT). Our sample consisted of 8 children and adolescents who had undergone surgical removal of a benign posterior fossa tumor (PFT) during childhood. None of them had undergone chemotherapy or cranial radiation therapy (CRT). Ages ranged from 1-11 years at surgery and 9-17 years at testing. The children were tested not earlier than 2.5 years after surgery (M = 5.9 years), enabling brain plasticity and recovery of functions. Their performance was compared with a matched control sample. The PFT group was not impaired in the implicit learning of sequences, as reflected in their performance in blocks with a repeated sequence, both before and after a random block. However, in the perceptual task, their performance deteriorated more than that of the control group when a random block was introduced, suggesting that it was more difficult for the patients to respond flexibly or change their response set when encountering changing task demands. These results are in line with another study by our group on task switching with the same patients.  相似文献   
948.
BACKGROUND: Fractures of the mandible are a common form of facial injury. The aetiological factors associated with mandibular fractures and the trends in these factors over a 10-year period are reported. METHODS: A retrospective survey was carried out of 724 patients presenting with a fracture of the mandible over the 10-year-period 1994-2003. Patients; records were reviewed and analyzed according to age, sex, cause of injury, anatomic site of fracture, treatment and postoperative complications. RESULTS: Over the 10-year-period the rate of mandibular fractures remained constant (mean 40,7%). There were no changes in the age group (mean 33,3 years) or in the higher prevalence in male (male-female-ratio 2,3 : 1). The major causes of fractures were assaults (38,6%) and accidental fall (27,3%). The most common fracture site was the condylar region (47,0%) followed by the angle (29,4%). Most fractures were treated by closed reduction until 2002, thereafter surgical treatment increased noticeable. The complication rate was 8,9% and the most common complications were hardware exposure and infection. CONCLUSION: Fractures of the mandible are a prevalent form of facial injury. Aetiological factors show no significant change over the 10-year-period. Complication-rate is low and will support the tendency towards surgical treatment.  相似文献   
949.
We present a new simple approach for automated, non-destructive measurement of the alpha-emitting radium isotopes ((223)Ra, (224)Ra, and (226)Ra) in water based on the emanation of their respective radon daughters ((219)Rn, (220)Rn, and (222)Rn). The method combines the high adsorption uptake of MnO(2) Resin for radium (K(d)=2.4 x 10(4)ml/g) over a wide pH range with the simplicity of the activity registration using a commercial radon-in-air analyzer (RAD7, DURRIDGE Company, Inc). Radium is first adsorbed onto the MnO(2) Resin by passing a water sample through the resin packed in a gas-tight glass cartridge. The same cartridge is then connected to the radon analyzer via a simple tubing system to circulate air through the resin and a drying system. The efficiency of the proposed system is determined by running standards prepared in the same manner. Our results indicate that the efficiency for (226)Ra is >22% if both (218)Po and (214)Po counts are collected. This is comparable with typical efficiencies for alpha spectrometry but with much less sample preparation. We estimate that an MDA of 0.8 pCi/L for (226)Ra may be obtained with this new approach using a 1L water sample and less than 4h of counting.  相似文献   
950.
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