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   2652265篇
  免费   194041篇
  国内免费   5150篇
耳鼻咽喉   36556篇
儿科学   88647篇
妇产科学   72770篇
基础医学   375320篇
口腔科学   74864篇
临床医学   237006篇
内科学   520463篇
皮肤病学   59553篇
神经病学   206698篇
特种医学   102653篇
外国民族医学   868篇
外科学   404563篇
综合类   59653篇
现状与发展   5篇
一般理论   849篇
预防医学   198945篇
眼科学   61807篇
药学   195021篇
  8篇
中国医学   6079篇
肿瘤学   149128篇
  2019年   20160篇
  2018年   29157篇
  2017年   22058篇
  2016年   24247篇
  2015年   27567篇
  2014年   38361篇
  2013年   57039篇
  2012年   78712篇
  2011年   83147篇
  2010年   49576篇
  2009年   46674篇
  2008年   78208篇
  2007年   83356篇
  2006年   84092篇
  2005年   80905篇
  2004年   78632篇
  2003年   75322篇
  2002年   73093篇
  2001年   134052篇
  2000年   137782篇
  1999年   115565篇
  1998年   30969篇
  1997年   27428篇
  1996年   27741篇
  1995年   26557篇
  1994年   24668篇
  1993年   22810篇
  1992年   89431篇
  1991年   86891篇
  1990年   84008篇
  1989年   80544篇
  1988年   73821篇
  1987年   72394篇
  1986年   67841篇
  1985年   64584篇
  1984年   48009篇
  1983年   40632篇
  1982年   23135篇
  1981年   20826篇
  1979年   42561篇
  1978年   29441篇
  1977年   25083篇
  1976年   23326篇
  1975年   25035篇
  1974年   29908篇
  1973年   28563篇
  1972年   26557篇
  1971年   24239篇
  1970年   22715篇
  1969年   20992篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The behavioural and physiological consequences of social status and reciprocal fighting in resident-intruder dyads of Long Evans male rats were evaluated. Before a chronic cohabitation of 10 days, residents and intruders were individually housed for one month to increase their aggressiveness. Control animals included isolates, i.e., animals kept individually housed throughout the experiment and pair-housed rats, i.e., pairs of rats housed together from their rats in the laboratory. In 19 out of 20 dyads, a clear dominance relationship developed with an advantage to the resident in 68% of the cases. Dominants showed more exploratory activity than subordinates in a open-field test at the end of the cohabitation period; subordinates groomed longer than animals from other experimental groups. Dominants had lower pain thresholds than individually and pair-housed animals. Both dominants and subordinates had higher tyrosine hydroxylase enzymatic activities in the left adrenal than isolated and pair-housed rats. Subordinates lost body weight and had higher plasma corticosteroid concentrations than animals from the other experimental groups. In addition, they had smaller thymus glands and reduced spleen lymphocyte responses to mitogenic stimulation in vitro, in comparison to dominant animals. These results show that subordination in the dyadic resident-intruder paradigm leads to a complex syndrome of behavioural and physiological changes, some of which may be modulated by the intensity of aggressive interactions.  相似文献   
993.
Although jejunoileal bypass surgery proved effective in controlling morbid obesity, the serious adverse effects from the operation were ultimately found to outweigh the benefits. Gastric partitioning results in weight loss by restricting the volume of food ingested rather than by interfering with absorption. Vertical banded gastroplasty has fewer complications than Roux-en-Y gastric bypass and is currently the surgical procedure of choice for morbid obesity.  相似文献   
994.
We describe a case of pathologic jealousy (Othello syndrome) in a patient with Parkinson disease, which abated after discontinuing amantadine. We indicate that early recognition and treatment of the syndrome in this disease may avert physical violence. We also believe that our report further suggests a link between this specific behavioral disorder and dopaminergic activity.  相似文献   
995.
The nuclear content, area and perimeter of the nucleus of lymphocytes in the C.S.F. were determined quantitatively by means of image analysis technique. 26 cases of central nervous system lymphocytic leukemia (CNLL), and 8 suspected cases were studied, other 56 cases who did not have leukemic and neoplastic diseases and had normal C.S.F. lymphocytes were taken as a control. Our data showed that all the mean nuclear content (MNC), mean nuclear area (MNA), mean nuclear perimeter (MNP), and the maximum and minimum nuclear contents of the 2 groups of former patients were obviously higher than those of the contral (P less than 0.01). These results presented suggestion that the image analysis technique can be used for differentiating the leukemic lymphocyte from normal one especially in suspected cases, and thus the diagnosis of CNLL might be improved.  相似文献   
996.
Behavioral state-specific changes in human hippocampal theta activity   总被引:1,自引:0,他引:1  
Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms.  相似文献   
997.
We have succeeded in recording short and middle latency vestibular evoked responses in human subjects. The head was held rigidly in a special, patented head holder, constructed individually for each subject, which gripped the teeth of the upper jaw. The stimulus consisted of 2/sec steps of angular acceleration impulses produced by a special motor with intensities of about 10,000 degrees/sec 2 and with a rise time of 1-2 msec. The electrical activity was recorded as the potential difference between special forehead and mastoid electrodes having a large, secure contact area with the skin. The activity was digitally filtered and averaged in 2 separate channels by means of a Microshev 2000 evoked response system. The short latency responses, with peaks at about 3.5 msec (forehead positive), 6.0 msec (forehead negative) and 8.4 msec (forehead positive; bandpass: 200-2000 Hz; average of 1024 trials), had amplitudes of about 0.5 microV. The middle latency responses had peaks at about 8.8 msec (forehead positive), 18.8 msec (forehead negative) and 26.8 msec (forehead positive; 30-300 Hz; N = 128 trials), with larger amplitudes (about 15 microV). These responses were consistently recorded in the same subject at different times and were similar in different normal subjects. Strenuous control experiments were conducted in order to ensure that these responses are not artefacts due to the movement of conducting media (head, electrodes and leads) in the electromagnetic field of the motor and are elicited by activation of normal labyrinths.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
998.
999.
Because of the trend toward a marked decrease in length of psychiatric hospitalization, clinicians need to improve the organization of the therapeutic milieu so that behavioral changes can be effected more rapidly. A university general psychiatric unit has adapted a problem-solving model that integrates groups and activities so that each one focuses on complementary behavioral objectives for each patient with the aim of effecting more rapid behavior change. The stages of the model are incorporated in a weekly sequence that begins with a goal-setting group. In a series of subsequent groups, each patient tries to develop and implement a solution to the problem identified that week. At the end of each week, patients participate in a goal review group, with feedback from staff and peers and self-reinforcement. The model can be used with a diverse patient population without interfering with each patient's individual psychotherapy or pharmacotherapy.  相似文献   
1000.
Burkitt's lymphoma, characterized by jaw and abdominal tumors, is the most common early childhood malignancy in Central Africa and well-known in the United States, with only sporadic reports coming from other countries. Considered to be the fastest growing tumor in man, it is thought to be of viral etiology with warm, humid climate and malaria regarded as co-factors. This is the first case of Burkitt's lymphoma reported from Greece.  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