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   4331篇
  免费   356篇
  国内免费   79篇
耳鼻咽喉   86篇
儿科学   115篇
妇产科学   42篇
基础医学   531篇
口腔科学   141篇
临床医学   521篇
内科学   832篇
皮肤病学   57篇
神经病学   364篇
特种医学   343篇
外科学   408篇
综合类   125篇
一般理论   1篇
预防医学   498篇
眼科学   61篇
药学   371篇
中国医学   9篇
肿瘤学   261篇
  2021年   59篇
  2020年   40篇
  2019年   53篇
  2018年   59篇
  2017年   47篇
  2016年   59篇
  2015年   62篇
  2014年   70篇
  2013年   130篇
  2012年   174篇
  2011年   182篇
  2010年   101篇
  2009年   113篇
  2008年   147篇
  2007年   187篇
  2006年   180篇
  2005年   177篇
  2004年   162篇
  2003年   133篇
  2002年   167篇
  2001年   151篇
  2000年   147篇
  1999年   127篇
  1998年   109篇
  1997年   108篇
  1996年   76篇
  1995年   86篇
  1994年   51篇
  1993年   55篇
  1992年   93篇
  1991年   105篇
  1990年   105篇
  1989年   110篇
  1988年   110篇
  1987年   89篇
  1986年   85篇
  1985年   107篇
  1984年   58篇
  1983年   44篇
  1982年   44篇
  1981年   36篇
  1980年   46篇
  1979年   53篇
  1978年   49篇
  1977年   39篇
  1976年   33篇
  1975年   35篇
  1974年   33篇
  1973年   31篇
  1971年   33篇
排序方式: 共有4766条查询结果,搜索用时 31 毫秒
1.
2.
3.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
4.
We examined several possible causes for the high incidence of poor sensory acuity in the limbs of 176 patients with moderate to severe peripheral vascular insufficiency. We investigated the relationships of diabetes, alcoholism, and smoking, as well as the severity of peripheral vascular disease, to the integrity of basic sensory modalities such as two-point discrimination and perception of light touch. The presence or absence of diabetes exerted the strongest effect on peripheral sensation. In patients who did not have diabetes, sensation in the limbs was most strongly affected by whether the patient was an alcoholic. Smoking did not have a significant effect on limb sensation. Among nondiabetic, nonalcoholic patients, there was a weak residual effect related to the severity of the peripheral vascular insufficiency. Even among these patients, however, systemic factors predominated in determining the loss of sensation. We also examined the extent to which loss of sensation might be related to the development of ulcers. Among patients who were not diabetic, there was a highly significant relationship between loss of sensation and the presence of limb ulceration. Surprisingly, however, there was no discernable relationship between the presence of ulcers in diabetic patients and the degree of loss of peripheral sensation. This result suggests that a large percentage of ulcers seen in diabetic patients are not of neurogenic origin.  相似文献   
5.
6.
Operative mortality, postoperative morbidity and follow up data were analyzed retrospectively from 122 consecutive patients, over 65 years old undergoing elective aortocoronary bypass grafting for symptomatic relief of angina pectoris at the Plains Health Centre, Regina, Saskatchewan, from January 1980 to December 1985. There were two in-hospital deaths (operative mortality 1.6%). Definite perioperative myocardial infarction occurred in 12 patients (9.8%). The 120 survivors were followed for a mean of 32 months. There were three deaths during follow-up, giving a five-year probability of survival of 93%. Twenty-three clinical events (including deaths) occurred during follow-up, giving a five-year probability of event free survival of 72%. Ninety percent of patients say they are pleased with their operation. Seventy-eight percent are currently angina free. These data illustrate the effectiveness of aortocoronary bypass grafting in low risk elderly patients with symptomatic coronary artery disease.  相似文献   
7.
8.
Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (Vm) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (Gmax = +dV/dtmax). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, Gmax was of a similar magnitude (551 ±30 and 555 ± 44 cm/s2, respectively) despite major differences in the respective D, Vm, Q and R values. In neither artery was there a relationship between Gmax and either resting Q or R. At the brachial artery level, Gmax was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between Gmax and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow.  相似文献   
9.
In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.  相似文献   
10.
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