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   2589774篇
  免费   185169篇
  国内免费   7594篇
耳鼻咽喉   34319篇
儿科学   85243篇
妇产科学   71586篇
基础医学   363767篇
口腔科学   69699篇
临床医学   234636篇
内科学   516122篇
皮肤病学   62467篇
神经病学   213640篇
特种医学   100000篇
外国民族医学   736篇
外科学   387026篇
综合类   50405篇
现状与发展   5篇
一般理论   968篇
预防医学   196255篇
眼科学   56768篇
药学   188065篇
  8篇
中国医学   5335篇
肿瘤学   145487篇
  2021年   20055篇
  2019年   20663篇
  2018年   29345篇
  2017年   22635篇
  2016年   26293篇
  2015年   29572篇
  2014年   40524篇
  2013年   60520篇
  2012年   80355篇
  2011年   84620篇
  2010年   51072篇
  2009年   49210篇
  2008年   79143篇
  2007年   83960篇
  2006年   85685篇
  2005年   81834篇
  2004年   78812篇
  2003年   76150篇
  2002年   73417篇
  2001年   128459篇
  2000年   131377篇
  1999年   110551篇
  1998年   31281篇
  1997年   27945篇
  1996年   28237篇
  1995年   27403篇
  1994年   25097篇
  1993年   23431篇
  1992年   85204篇
  1991年   81596篇
  1990年   78822篇
  1989年   76099篇
  1988年   69513篇
  1987年   68029篇
  1986年   63569篇
  1985年   60543篇
  1984年   44956篇
  1983年   37957篇
  1982年   22463篇
  1981年   19986篇
  1979年   38976篇
  1978年   27446篇
  1977年   23264篇
  1976年   21503篇
  1975年   22821篇
  1974年   26798篇
  1973年   25377篇
  1972年   23758篇
  1971年   21968篇
  1970年   20191篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Short latency auditory nerve and brainstem evoked responses (BAERs) and long latency cortical auditory evoked responses (CAERs) in 75 long-term traumatic brain injury (TBI) cases were compared. CAERs were found to be significantly correlated with clinical disability as measured by the Disability Rating Scale, while BAERs were not. Also, BAER patterns were consistently and significantly less abnormal and less sensitive to overall dysfunction than CAER patterns. Findings support previous observations that BAERs have relatively little utility for evaluating in surviving TBI patients the degree of overall brain impairment. In general, long latency AEP patterns are better able to reflect the extent and severity of brain dysfunction and overall clinical condition than are short latency AEP patterns in long-term severe TBI patients, and these patterns should be obtained routinely in the evaluation of such patients.  相似文献   
992.
The detection of antineuronal antibodies against cytoplasm and nuclei of Purkinje cells is considered to be an essential factor in the diagnosis of neurologic paraneoplastic syndromes. Published data rely on different immunological methods and relatively small numbers of patients. The clinical relevance of this phenomenon is not clear from the literature. A positive correlation between antibody detection and the appearance of neurologic paraneoplastic syndromes has been reported, but this finding has been questioned in critical reviews.  相似文献   
993.
Higher cerebral dysfunctions such as aphasia, apraxia and agnosia have seldom been reported in multiple sclerosis (MS). 12 year-old right-handed boy felt unsteadiness of the body and headache for several days. Two months later, he had the same episode and complained of visual disturbance, and weakness and sensory disturbance on the face and the extremities. Additionally, he showed amnestic aphasia, acalculia, ideomotor apraxia, finger agnosia and right-left disorientation. Cerebrospinal fluid examinations revealed increases IgG, myelin basic protein and neuron specific enolase (11%, 25 ng/ml and 28.8 ng/ml, respectively). X-ray CT scan and MRI-CT examinations revealed sclerotic lesions on the left parietal white matter and the right mid-brain. The diagnosis was made as MS. He was treated with m-PSL (methyl-prednisolone) pulse therapy for three weeks and consecutively treated with PSL for four weeks. He recovered gradually, but visual disturbance and facial palsy remained. After seven months MRI-CT showed a high signal intensity on the left parietal white matter in spite of the disappearance of the lesion on X-ray CT scan. We suggest that these higher cerebral dysfunctions may result from the lesion of the left parietal white matter which produces a disconnection between each cortical area.  相似文献   
994.
To clarify when and how rapidly individual muscles are damaged in the course of Duchenne muscular dystrophy (DMD), we followed X-ray CT of whole body skeletal muscles from 29 cases of DMD patients (age ranging 3 to 23 years) for a period of 2 to 6 years. Each patient had 2 to 5 scans with an average of 3.3. We evaluated chronological changes of 23 muscles from the entire body using the muscle damage stage defined as follows. The stages were classified into the following 5 stages: stage 0; normal, 1; area of fatty replacement less than 10% of whole muscle area, 2; area of fatty replacement between 10 to 50%, 3; area of fatty replacement 50 to 90%, 4; almost complete fatty replacement. Each muscle had its own period of rapid degeneration starting at 5 to 10 years of age and, continuing 5 to 10 years. In some muscles such as gluteus maximus or quadriceps femoris, fatty replacement started at 5 years or earlier and progressed for five years, while other muscles such as splenius capitis, damage started much later, e.g. around 10 years of age and the progression was much slower. There was a variation of at least 5 years among individual patients in any muscle damage stage, reflecting the variability of clinical severity in each patient. On the basis of the above results we defined the whole body muscle damage index as a summation of the muscle damage stages of the following five muscles: gluteus maximus, quadriceps femoris, gracilis, medial head of gastrocnemius and splenius capitis.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
995.
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   
996.
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   
997.
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   
998.
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   
999.
Thyroid function tests were studied in 105 severely disabled children. Fifty-four cases (53%) showed following abnormalities. Serum TSH concentration was increased in 2 cases. Both serum T4 and T3 levels were decreased in 18 cases (17%). Only the serum T4 level was decreased in 25 cases (24%). Only the serum T3 level was decreased in 10 cases (9.5%). Two patients showed primary hypothyroidism. Two patients (monozygotic twins) were suspected to have subclinical hypothalamic-pituitary hypothyroidism caused by septo-optic-dysplasia. Abnormal thyroid functions were caused by anticonvulsants in most patients. The serum T4 level was correlated with the number of anticonvulsants, but not correlated with motor performance (daily activity) or feeding function. Four patients who had low T4 level or low T4 and T3 levels were received L-thyroxine supplementation, but no clinical improvement was observed. The serum TSH concentration was decreased and the TRH test showed hyporeaction in all of these cases. The low T3 level and normal T4 level were not related to anticonvulsant administration. Two of these patients were in poor nutritional condition, resulting in so called low T3 syndrome.  相似文献   
1000.
Twenty-two days after administration by intravenous bolus, of 50 mg of adriamycin to several patients we found concentrations of adriamycin and adriamycinol of the order of 100 pcg/ml. In theory, however, with a terminal half-life of 30 h, the plasma levels of adriamycin and adriamycinol should be close to 0.1 pcg/ml. Further pharmacokinetic investigation was therefore necessary. We have retained for this study nine male patients, aged between 53 and 69 years who received 25 to 50 mg of adriamycin by slow intravenous injection. The HPLC method permitted the detection of 50 pcg/ml of adriamycin and adriamycinol, with the possibility of monitoring their elimination during 120 h (and in one case during 160 h). The terminal half-lives of elimination estimated in 8 patients were respectively 110 +/- 52 h for adriamycin and 92 h 50 min +/- 43 h for adriamycinol. Surface ratios under adriamycinol curves against calculated adriamycin was 1.10 +/- 0.26. Plasma levels found during the To in certain patients correspond to the end of the drug elimination of the previous treatment. It is difficult with a half-life to 110 h to predict the effects of residual concentrations of adriamycin and adriamycinol.  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