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   2998394篇
  免费   232689篇
  国内免费   5162篇
耳鼻咽喉   43508篇
儿科学   89155篇
妇产科学   78638篇
基础医学   422786篇
口腔科学   88164篇
临床医学   270607篇
内科学   584499篇
皮肤病学   61409篇
神经病学   247333篇
特种医学   119168篇
外国民族医学   941篇
外科学   461702篇
综合类   68290篇
现状与发展   2篇
一般理论   1157篇
预防医学   232793篇
眼科学   70602篇
药学   227385篇
  7篇
中国医学   5870篇
肿瘤学   162229篇
  2018年   29801篇
  2016年   25519篇
  2015年   28894篇
  2014年   41198篇
  2013年   62339篇
  2012年   84240篇
  2011年   88815篇
  2010年   52384篇
  2009年   50242篇
  2008年   84988篇
  2007年   90084篇
  2006年   91439篇
  2005年   88998篇
  2004年   85808篇
  2003年   82700篇
  2002年   81614篇
  2001年   145846篇
  2000年   151094篇
  1999年   127566篇
  1998年   34952篇
  1997年   31553篇
  1996年   31372篇
  1995年   30177篇
  1994年   28332篇
  1993年   26311篇
  1992年   101949篇
  1991年   98365篇
  1990年   95016篇
  1989年   91944篇
  1988年   84999篇
  1987年   83383篇
  1986年   78825篇
  1985年   75372篇
  1984年   56241篇
  1983年   47961篇
  1982年   28004篇
  1981年   24827篇
  1980年   23207篇
  1979年   52142篇
  1978年   36248篇
  1977年   30770篇
  1976年   28307篇
  1975年   30242篇
  1974年   37199篇
  1973年   35287篇
  1972年   33187篇
  1971年   30868篇
  1970年   29083篇
  1969年   27222篇
  1968年   24713篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The erythrocyte membrane transports (MT) of L-tyrosine and L-tryptophan, as well as their plasma levels, were measured in 143 depressed patients after a wash-out period of one week and before any antidepressant treatment, and then at regular intervals until they recovered. 49 normal subjects served as a control group. The perturbations of these biologic variables at baseline were different according to diagnostic groups (DSM III), compared to controls: significant decrease of the two MT in depressed bipolar disorders; significant decrease of MT in depressed bipolar disorders; significant decrease of MT tyrosine and significant increase of MT tryptophan in recurrent major depressions; no significant changes of MT in dysthymic disorders. The plasma levels of tyrosine and total tryptophan show a significant diminution in the 3 groups. The study of the evolution of these same variables after antidepressant treatment show a return to normal of the MT at recovery, as well as the plasma levels of tyrosine. The plasma levels of tryptophan stay low in depressed bipolar disorders and recurrent major depressions.  相似文献   
992.
993.
Eighty-eight of 143 hospitals in New York State providing psychiatric inpatient treatment responded to a mailed questionnaire designed to determine the size of three subgroups of chemical abusers--alcohol abusers, drug abusers, and polychemical abusers--among inpatients with psychiatric diagnoses, as well as the availability of services for these patients. Data for New York City and its metropolitan area were analyzed separately. In 1987 almost one-third of psychiatric admissions both in and outside the metropolitan area had comorbid chemical abuse disorders. Seventy-five percent of patients in the metropolitan area with comorbid chemical abuse had a drug abuse disorder; in rural areas 88 percent of patients with chemical abuse disorders abused alcohol. Both hospital- and community-based aftercare services, especially in the metropolitan area, were less available to psychiatric patients with chemical abuse than to patients without these disorders.  相似文献   
994.
Two experiments examined the ingestive responses of streptozotocin-diabetic rats fed low-fat or high-fat diets to glucose, fructose, sucrose and maltose solutions in brief (30 min) intake tests. In Experiment 1, one-bottle acceptability tests were used whereas two-bottle preference tests were used in Experiment 2. Three main findings resulted from these studies. Firstly, diabetic rats fed the low-fat diet displayed a reduced acceptance of and preference for all concentrated sugar solutions. Secondly, glucose consumption patterns of diabetic rats fed the low-fat diet were distinctly different from their responses to the other sugars. Thirdly feeding high-fat diets, either high or low in carbohydrate, normalized the responses of diabetic rats to the sugar solutions. The results suggest that feeding high-fat diets to diabetic rats normalizes their responses to sugar solutions because of reductions in hunger and thirst associated with the provision of a utilizable source of calories and an improvement in body fluid balance.  相似文献   
995.
A seven-month-old girl with atypical West syndrome with pedaling automatism was reported. She started to have early infantile epileptic encephalopathy with suppression-burst (EIEE) at age 14 days followed by infantile spasms at 3 months of age. She began to have spasms with automatism at 4 month, mainly consisting of pedaling movements of both feet associated with tonic spasms of upper extremities and writhing of trunk. Ictal EEG showed irregular slow waves with occasional spikes predominantly over the right hemisphere mixed with artifacts. Interictal EEG during sleep showed suppression-burst patterns. Cerebral atrophy and microcephaly were revealed on brain CT, immature myelination on MRI and decreased blood flow in the frontal, temporal, and parietal lobes on the right on PET scan. Pedaling automatism is rare in infancy and its clinical significance was discussed in relation to West syndrome and complex partial seizures.  相似文献   
996.
Pattern visual evoked potentials were obtained from 46 patients with definite relapsing/remitting multiple sclerosis, using both a conventional 5-channel occipital array and a 3-D recording technique consisting of three bipolar derivations approximating the three dimensions of space. These three orthogonal wave forms were displayed as a 3-D Lissajous trajectory for each subject. Two of the 15 patients with completely normal conventional pattern VEPs had abnormalities of the orientation of the B-C curvilinear segment of the 3-D pattern VEPs. Delays in the first major occipital positive component (P100) were evident using both techniques; the correlation between P100 latency and the latency of the corresponding trajectory apex was r = 0.99 (P less than 0.01). Post-chiasmal MRI abnormalities were associated with 3-D VEP orientation abnormalities. Three-dimensional pattern VEPs are moderately more sensitive than conventional pattern VEPs at detecting dysfunction posterior to the optic chiasm in demyelinating disease and do not require the use of eccentric fixation to do so.  相似文献   
997.
998.
999.
Following an encephalopathic illness, a 13-year-old Chinese boy had a partial form of Klüver-Bucy syndrome with emotional disturbance, recent memory loss, hypersexuality, and polyphagia. Other unusual features included narcolepsy, polydipsia, and polyuria. Virologic studies failed to incriminate the etiologic agent, including herpes simplex virus. Brain biopsy of the frontal lobe demonstrated Alzheimer type II astrocytosis.  相似文献   
1000.
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