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   2668篇
  免费   183篇
  国内免费   11篇
耳鼻咽喉   20篇
儿科学   295篇
妇产科学   34篇
基础医学   392篇
口腔科学   20篇
临床医学   182篇
内科学   449篇
皮肤病学   36篇
神经病学   367篇
特种医学   204篇
外科学   332篇
综合类   74篇
预防医学   190篇
眼科学   20篇
药学   108篇
中国医学   6篇
肿瘤学   133篇
  2021年   36篇
  2019年   29篇
  2018年   25篇
  2016年   39篇
  2015年   69篇
  2014年   35篇
  2013年   71篇
  2012年   87篇
  2011年   102篇
  2010年   65篇
  2009年   59篇
  2008年   92篇
  2007年   67篇
  2006年   91篇
  2005年   87篇
  2004年   65篇
  2003年   70篇
  2002年   66篇
  2001年   65篇
  2000年   65篇
  1999年   74篇
  1998年   47篇
  1997年   64篇
  1996年   69篇
  1995年   54篇
  1994年   51篇
  1993年   51篇
  1992年   69篇
  1991年   63篇
  1990年   61篇
  1989年   93篇
  1988年   65篇
  1987年   67篇
  1986年   73篇
  1985年   57篇
  1984年   48篇
  1983年   52篇
  1982年   43篇
  1981年   33篇
  1980年   28篇
  1979年   34篇
  1978年   33篇
  1977年   24篇
  1976年   25篇
  1975年   28篇
  1973年   24篇
  1972年   37篇
  1971年   27篇
  1970年   24篇
  1969年   17篇
排序方式: 共有2862条查询结果,搜索用时 15 毫秒
1.
The authors report the association of erythroleukemia (FAB M6) and fetal hemoglobin (HbF) level of at least 65% after therapy for ovarian carcinoma. The patient's erythrocytes had many signs of reversion to fetal-like erythropoiesis including: elevated HbF with a fetal G gamma/A gamma (gly/ala) of 3/1, low hemoglobin A2 (HbA2), macrocytosis, and increased i antigen. These data and data from other case reports suggest that elevation of HbF to greater than 25% with reversion to fetal-like erythropoiesis is useful in differentiating erythroleukemia from other preleukemic disorders.  相似文献   
2.
3.
Behavioral measurement of axonal thresholds   总被引:1,自引:0,他引:1  
A behavioral method for measuring the electrical sensitivity of directly stimulated elements in the brain is described and applied to the medial forebrain bundle (MFB) reward path and the tectospinal circling path. Equations are derived from which threshold current densities may be calculated from knowledge of the electrode tip dimensions and the current required to produce criterion behavior, which is a function of electrode size. Four different sizes of electrode were implanted in the MFB of rats and self-stimulation rates plotted against stimulating current. The mean currents for criterion bar-pressing rates of 25% and 55% of maximum rate were determined for each electrode size and the values used to calculate average threshold current densities. Two sizes of electrode were implanted in the tectospinal tract of rats and the average currents to produce circling at 0.2 and 0.4 turns/s were measured. The threshold current densities for self-stimulation axons were about 5 times as large as those for circling, in accordance with other evidence that tectal circling path axons are larger than those of the MFB reward path.  相似文献   
4.
Neural activity was recorded from the median nerve of a monkey during grasping and lifting, using a chronically implanted cuff electrode. At the onset of lifting, there was an initial dynamic response during which the intensity of the neural signal increased rapidly. This neural response attained its peak value well before the displacement, the load force or the grip force. The time course and peak of the rectified, integrated neurogram were best correlated with the rate of change of grip force. The neural activity declined exponentially to a steady value following the initial peak. During steady holding the mean amplitude of the neurogram was best correlated with the mean grip force. At the end of the holding phase there was a short burst of neural activity as the monkey relaxed the grip force and released the object. During some blocks of trials pulse perturbations were applied to the object. When the monkey did not increase the grip force in advance of the perturbation, the perturbation produced a relatively large displacement of the object and a burst of neural activity whose onset coincided with the onset of displacement. When the monkey anticipated the perturbation by increasing the grip force during the holding period preceding the perturbation, the perturbation produced a relatively small displacement and relatively little increase in neural activity.  相似文献   
5.
In the upper limb, diffuse cavernous haemangiomas occur infrequently but their treatment is often unsatisfactory and the result of surgical excision disappointing. Four cases of these diffuse haemangiomas are described and their management discussed.  相似文献   
6.
Right temporal-lobe contribution to global visual processing   总被引:1,自引:0,他引:1  
J Doyon  B Milner 《Neuropsychologia》1991,29(5):343-360
The performance of 92 patients with unilateral temporal- or frontal-lobe excisions and 35 normal control subjects was tested under two experimental conditions (global, local) of a Stroop-type reaction-time task, employing either hierarchically structured letters or abstract designs as stimuli. In the local condition, subjects were asked to focus their attention on the small forms and to ignore the large form, whereas they were instructed to do the reverse in the global condition. The results showed that, in the local condition, the patients with right temporal-lobe lesions were less affected than the other groups by interference from the global aspect of the stimulus. This reduced sensitivity to the overall configuration of the stimulus was unrelated to the extent of hippocampal removal or to the presence of visual-field defects. These findings support the hypothesis that the human right temporal neocortex contributes to the global processing of visual information.  相似文献   
7.
8.
Breast augmentation is one of the most frequently performed cosmetic surgery procedures worldwide. We report on a series of 502 consecutive cosmetic breast augmentations by a single surgeon, using both the submuscular and submammary approaches. A vacuum drain was placed in the surgical pocket at the end of the procedure. The drain fluid collection was recorded immediately after the surgery and the following day before removal. A tenfold increase in the amount of fluid collection was noted in the drain’s reservoir. Thirteen patients presented with minor wound healing problems at the second postoperative follow-up, which were treated conservatively; two of them had the implant removed and replaced after 2 months. There were only two capsular contractions at 1-year follow-up. We focus our discussion on the drainage in the early postoperative period and conclude that the routine use of a surgical drainage reduces the risk for complications. Based on our findings, we advocate that short-term routine use of a surgical drain is advisable.  相似文献   
9.
BACKGROUND: We recently implemented the use of an ex-vivo porcine model to teach residents the fundamentals of performing a laparoscopic Nissen fundoplication. METHODS: Residents were trained using intact porcine esophagus, stomach, and spleen placed in a standard video-trainer. They were later asked to complete a survey containing a course evaluation. RESULTS: Sixteen residents (R1-R4) completed the survey. They agreed that (1) the exercise was a valuable use of their limited time, (2) repeating the exercise will be of additional benefit, (3) it will improve their ability to perform or assist in an actual case in the OR, and (4) the surgical principles learned using the model will transfer to other laparoscopic cases. Significant subjective improvements were reported in resident comfort level in assisting in or performing a laparoscopic Nissen fundoplication. CONCLUSIONS: The use of an inexpensive ex-vivo porcine training model increases resident comfort level in performing a Nissen fundoplication in the operating room.  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