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   24546篇
  免费   1309篇
  国内免费   86篇
耳鼻咽喉   153篇
儿科学   399篇
妇产科学   403篇
基础医学   3152篇
口腔科学   806篇
临床医学   1784篇
内科学   5886篇
皮肤病学   455篇
神经病学   2207篇
特种医学   1087篇
外科学   3603篇
综合类   94篇
一般理论   1篇
预防医学   767篇
眼科学   454篇
药学   2014篇
中国医学   56篇
肿瘤学   2620篇
  2023年   102篇
  2022年   231篇
  2021年   426篇
  2020年   245篇
  2019年   350篇
  2018年   405篇
  2017年   303篇
  2016年   390篇
  2015年   437篇
  2014年   574篇
  2013年   687篇
  2012年   1098篇
  2011年   1236篇
  2010年   631篇
  2009年   593篇
  2008年   1089篇
  2007年   1124篇
  2006年   1098篇
  2005年   1076篇
  2004年   1028篇
  2003年   1026篇
  2002年   1023篇
  2001年   934篇
  2000年   950篇
  1999年   940篇
  1998年   319篇
  1997年   248篇
  1996年   232篇
  1995年   197篇
  1994年   175篇
  1993年   163篇
  1992年   661篇
  1991年   572篇
  1990年   603篇
  1989年   584篇
  1988年   495篇
  1987年   458篇
  1986年   453篇
  1985年   404篇
  1984年   280篇
  1983年   236篇
  1980年   93篇
  1979年   241篇
  1978年   145篇
  1977年   129篇
  1975年   100篇
  1974年   96篇
  1972年   105篇
  1971年   103篇
  1969年   101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Purpose

Suppression of respiratory movement of the liver would be desirable for high-precision radiation therapy for liver tumors. We aimed to investigate the effect of our original device-free compressed shell fixation method and breathing instruction on suppression of respiratory movement. The characteristics of liver motion based on the movement of a fiducial marker were also analyzed.

Methods and Materials

First, respiratory amplitudes of the liver with the device-free compressed shell were analyzed from the data of 146 patients. The effect of this shell fixing method on liver movement was evaluated. Second, as another cohort study with 166 patients, interfractional internal motion of the liver for patients fixed in the shell was calculated using the fiducial marker coordinate data of images for position setting before daily irradiation. Third, in another 12 patients, intrafractional internal motion was calculated from the fiducial marker coordinate data using x-ray images before and after irradiation.

Results

The median respiratory movement without the shell, after fixing with the shell, and after instructing on the breathing method with the shell was 14.2 (interquartile range, 10.7-19.8), 11.5 (8.6-17.5), and 10.4 mm (7.3-15.8), respectively. Systematic and random errors of interfractional internal motion were all ≤2 mm in the left-right and anteroposterior directions and 3.7 and 3.0 mm, respectively, in the craniocaudal direction. Systematic and random errors of intrafractional internal motion were all ≤1.3 mm in the left-right and anteroposterior directions and 0.8 and 2.4 mm, respectively, in the craniocaudal direction.

Conclusions

The device-free compressed shell fixation method was effective in suppressing the respiratory movement of the liver. Irradiation position matching using the fiducial marker can correct the interfractional internal motion on each day, which would contribute to the reduction of the margin to be given around the target.  相似文献   
2.
3.
Idiopathic myointimal hyperplasia of mesenteric veins (IMHMV) is a rare and poorly understood ischemic colitis that occurs in the rectosigmoid colon of predominantly young, previously healthy, male patients. A 76‐year‐old Japanese man presented to our hospital with a 1‐year history of worsening diarrhea, lower abdominal pain, and weight loss (−6 kg). Laboratory evaluation revealed white blood cell count of 13 200/μL, C‐reactive protein level of 2.0 mg/dL (normal range, 0.0–0.3), and negative results for stool culture (including Clostridium difficile). Colonoscopy showed circumferential and edematous narrowing of the sigmoid colon with deep longitude ulceration. Biopsy was done and examination of the specimen demonstrated no specific ischemia. The patient was treated with bowel rest, antibiotics, and i.v. fluids; however, his symptoms worsened. Finally, sigmoidectomy was carried out. Histological examination demonstrated significant myointimal hyperplasia of mesenteric veins leading to thickening and stenosis of the venous lumen. Therefore, the final diagnosis was IMHMV. Three months following sigmoidectomy, he was asymptomatic.  相似文献   
4.
5.
6.
7.
8.
9.
Experiments were performed on spinalized rats, transected at the Cl level. The intravenous administration of TRH and its analog YM-14673 (N alpha-[(S)-4-oxo-2-azetidinyl) carbonyl]-L-histidyl-L-prolinamide dehydrate) produced marked increases in the amplitude of mono- and polysynaptic reflex potentials and those of the withdrawal flexor reflexes. The effects of YM-14673 were stronger and longer-lasting than those of TRH. The stimulant action of TRH and YM-14673 on the flexor reflexes was not antagonized by prazosin, chlorpromazine, haloperidol or cyproheptadine, suggesting no involvement of the release of catecholamines or serotonin in the stimulant effects of TRH and its analog. Therefore, YM-14673 may be beneficial for the treatment of several spinal motor neuron diseases.  相似文献   
10.
S Yamada 《Journal of UOEH》1988,10(2):211-218
Physical activity and nutrition are the most important factors in preserving and/or improving health conditions. The relationship between exercise and nutrition is focused on two different directions: one is the direction toward health promoting, the other is for performance of a long heavy muscular work. For preserving and/or promoting health conditions, energy balance between intake and expenditure must be taken into account. The amount of glycogen stored in muscles is the essential factor to promote a long distance performance of working muscles. Topics that influence the energy balance and glycogen loading used by endurance athletes to improve performance are reviewed.  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