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   295609篇
  免费   44801篇
  国内免费   6283篇
耳鼻咽喉   4734篇
儿科学   7040篇
妇产科学   4958篇
基础医学   22550篇
口腔科学   8956篇
临床医学   47396篇
内科学   56258篇
皮肤病学   6233篇
神经病学   25146篇
特种医学   11073篇
外国民族医学   4篇
外科学   41838篇
综合类   23535篇
现状与发展   52篇
一般理论   167篇
预防医学   33832篇
眼科学   5871篇
药学   18312篇
  121篇
中国医学   8627篇
肿瘤学   19990篇
  2024年   1230篇
  2023年   6525篇
  2022年   4503篇
  2021年   7908篇
  2020年   9267篇
  2019年   5421篇
  2018年   10642篇
  2017年   11131篇
  2016年   11306篇
  2015年   13398篇
  2014年   17635篇
  2013年   22207篇
  2012年   18292篇
  2011年   18951篇
  2010年   18027篇
  2009年   19335篇
  2008年   17115篇
  2007年   16432篇
  2006年   16623篇
  2005年   14429篇
  2004年   12183篇
  2003年   11250篇
  2002年   10251篇
  2001年   4618篇
  2000年   3163篇
  1999年   3384篇
  1998年   4023篇
  1997年   3585篇
  1996年   3363篇
  1995年   3029篇
  1994年   2184篇
  1993年   2031篇
  1992年   1594篇
  1991年   1419篇
  1990年   1255篇
  1989年   1230篇
  1988年   1153篇
  1987年   1002篇
  1986年   987篇
  1985年   1022篇
  1984年   1115篇
  1983年   1181篇
  1982年   1430篇
  1981年   1297篇
  1980年   1110篇
  1979年   554篇
  1978年   715篇
  1977年   702篇
  1976年   558篇
  1975年   487篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
(1) The estrous cycle in the rat may be used to study recurrent changes in motor behaviors and motivation which are strongly related to cyclic hormonal and CNS changes. (2) The peak in motivated behaviors occurs during a sharply defined period on the night between proestrus and estrus and is evident in facilitated wheel-running, lordosis, and intracranial self-stimulation. (3) Behaviors without a clearly motivated character do not show an estrous cyclicity. (4) The estrous cyclic variation in intracranial self-stimulation was observed at a specific locus — the pars campacta of the substantia nigra. (5) A neurochemical link between sexually motivated behavior, wheel running and intracranial self-stimulation is suggested. This link is in part dopaminergic but is probably also activated by many other systems.  相似文献   
42.
Summary An infant girl is described who had cor triatriatum and partial anomalous pulmonary venous connection of the left pulmonary veins to the coronary sinus, the first report of this combination of lesions. The infant also had a Dandy-Walker malformation and multiple facial and intrathoracic hemangiomas. The cardiac diagnosis was made by two-dimensional echocardiography. Cardiac catheterization and angiography confirmed the findings and also demonstrated a persistent left superior vena cava draining to the coronary sinus. The infant underwent successful surgical repair. Partial anomalous pulmonary venous connection and left superior vena cava not infrequently are associated with cor triatriatum. Although two-dimensional echocardiography is sensitive for the detection of cor triatriatum, preoperative cardiac catheterization is necessary to identify unequivocally systemic and pulmonary venous connections.  相似文献   
43.
44.
45.
Patients at Boston's Children's Hospital diagnosed as having cerebral palsy were filmed walking. These films were digitized and translated into measurements associated with leg motion. In this paper we use the gait measurements of 128 such patients to illustrate that the kth nearest neighbour clustering procedure results in a gait typology for patients with cerebral palsy. The procedure identifies four subpopulations from the sample data; the membership of a patient within this typology is mostly determined by the patient's motor control. The developed typology differs from the present diagnostic system which classifies a cerebral palsy patient as either quadriplegic, diaplegic or hemiplegic.  相似文献   
46.
47.
48.
Directors of nursing at 23 nursing homes with Alzheimer's units in Southwestern Pennsylvania completed a self‐reported survey of 12 questions. Responses from the self‐administered questionnaires (100% response rate) revealed a wide variation in the staff categories assessing the oral health status of newly admitted residents with AD. The respondents described oral examinations that were incomplete when compared to the oral indicators listed in the Minimum Data Set. All nursing homes reported that oral hygiene was provided each day. The number of residents in a facility had a significant effect on the frequency of oral hygiene provided. Only 52% of the facilities reported yearly oral examinations for this population. According to the respondents, dental treatment was typically performed on‐site. The oral health care costs were paid by Medicare, Medicaid, the residents/family members, or by other undescribed resources. Insufficient time, staff, and training, as well as uncooperative behavior, were identified as barriers to optimum oral health care for residents with AD. Additional staff, specialized training, and increased government reimbursement were suggested to improve the oral health care for this group of older adults. For future studies, review of medical records and on‐site evaluation of the oral health care at these facilities should be required to verify the reported practices.  相似文献   
49.
Several cell lines secreting monoclonal antibodies (Mabs) against a major forebrain synaptic membrane (SM) glycoprotein, gp 50, have been raised. Western blots show that the Mabs react with a polypeptide doublet of Mrs 49 and 45 kDa. These polypeptides exist solely in a concanavalin A (Con A) binding form. Removal of the Con A receptors by digestion with endo-beta-N-acetylglucosaminidase H (endo H) lowers the Mrs of the glycoprotein doublet to 36.5 and 34 kDa. Western blots of 2D polyacrylamide gels indicate that gp 50 exists in several isoforms. Solid phase radioimmunoassay (RIA) and Western blots of brain subcellular fractions show the antigenic material to be concentrated in the SM fraction, but to be present in much lower amounts in synaptic junctions and postsynaptic densities. Gp 50 appears to be brain specific. Regional distribution studies show that it is present in all brain regions but is two-fold concentrated in cerebellum, brainstem and midbrain compared to forebrain. Immunocytochemical studies of several brain regions show that gp 50-like immunoreactivity is neuron specific and is concentrated in selected neuronal species, particularly granule cells. In both cerebellar and hippocampal granule cells gp 50-like immunoreactivity is localized in the perikarya and primary dendrites. Though immunocytochemistry did not show staining of synaptic regions this may be due to masking of the reactive epitope. The results are discussed in terms of the molecular properties of gp 50 and its subcellular localization in brain tissue.  相似文献   
50.
19 polygraphic sleep recordings from 12 patients with Pick's Disease, including four histologically proved cases, were compared to those of an age-matched control group. Symptoms had been present for a mean 8 years, the patients being aged 59 to 78 (mean 70.5 years). All sleep stages could be identified. Total sleep time was reduced and the number of awakenings was sharply increased. High proportion of stage 1 contrasted with the reduction in the other sleep stages with disappearance of stage 4 in advanced cases. REM Sleep was identified in all recordings, although reduced as a function of the length of the illness; its production as a function of total sleep time was not different from that of the control. REM Sleep appeared often fragmented and with a remarkably short latency, reminiscent of that observed in severely depressed patients.  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