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   31597篇
  免费   2366篇
  国内免费   364篇
耳鼻咽喉   272篇
儿科学   782篇
妇产科学   568篇
基础医学   3712篇
口腔科学   415篇
临床医学   3294篇
内科学   6005篇
皮肤病学   776篇
神经病学   2587篇
特种医学   1168篇
外国民族医学   1篇
外科学   4690篇
综合类   1357篇
一般理论   60篇
预防医学   2619篇
眼科学   998篇
药学   2410篇
  1篇
中国医学   328篇
肿瘤学   2284篇
  2023年   200篇
  2022年   378篇
  2021年   638篇
  2020年   409篇
  2019年   528篇
  2018年   608篇
  2017年   529篇
  2016年   562篇
  2015年   692篇
  2014年   969篇
  2013年   1317篇
  2012年   1918篇
  2011年   1962篇
  2010年   1136篇
  2009年   1004篇
  2008年   1783篇
  2007年   1894篇
  2006年   1852篇
  2005年   1921篇
  2004年   1787篇
  2003年   1689篇
  2002年   1632篇
  2001年   536篇
  2000年   459篇
  1999年   477篇
  1998年   419篇
  1997年   390篇
  1996年   351篇
  1995年   341篇
  1994年   287篇
  1993年   258篇
  1992年   311篇
  1991年   286篇
  1990年   259篇
  1989年   264篇
  1988年   227篇
  1987年   212篇
  1986年   210篇
  1985年   230篇
  1984年   224篇
  1983年   225篇
  1982年   251篇
  1981年   261篇
  1980年   213篇
  1979年   169篇
  1978年   179篇
  1977年   172篇
  1976年   116篇
  1975年   133篇
  1974年   144篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
采用鼠抗PCNA单克隆抗体,ABC法,对11例正常口腔粘膜及29例口腔鳞癌进行了染色。结果表明:正常粘膜仅在基底层中有少量的PCNA阳性细胞,其阳性分级为1级。而鳞癌阳性分级主要是3~4级,随着组织学分级的升高,PCNA阳性表达率也相应增高。经统计学分析,正常组织与鳞癌之间及鳞癌各级均有非常显著差异(P<001)。提示:PCNA的表达与口腔鳞癌组织学分级有关。  相似文献   
102.
The present study has employed in vitro electrophysiology and radioligand binding assays to determine whether dopamine and adenosine receptors interact with each other on rat vagal afferent neurons. Preincubation of the isolated rat nodose ganglion with the adenosine A2a agonists CGS 21680 or DPMA (Both 1 μM) resulted in a functional antagonism of the ability of dopamine to depolarise the preparation. Specifically, the concentration-response curve to dopamine was significantly shifted to the right in the presence of CGS 21680 and DPMA. On the other hand, adenosine itself, A1 and A3 receptor agonists and ATP were all incapable of modulating the electrophysiological response to dopamine. In contrast to the nodose ganglion, CGS 21680 did not significantly affect the ability of the dopamine D2 ligands quinpirole or raclopride to displace [125I]NCQ298 binding to dopamine D2 receptors in membranes prepared from rat dorsal brain stem. These data indicate the presence of an interaction between high affinity adenosine A2 receptors and dopamine D2 receptors on the soma of rat vagal afferent neurons, whereas the situation in the brain stem remains less clear. Received: 17 September 1996 / Accepted: 20 October 1996  相似文献   
103.
The current study presents both longitudinal behavioral data and functional activation data documenting the effects of early focal brain injury on the development of spatial analytic processing in two children, one with prenatal left hemisphere (LH) injury and one with right hemisphere (RH) injury. A substantial body of evidence has shown that adults and children with early, lateralized brain injury show evidence of spatial analytic deficits. LH injury compromises the ability to encode the parts of a spatial pattern, while RH injury impairs pattern integration. The two children described in this report show patterns of deficit consistent with the site of their injury. In the current study, their longitudinal behavioral data spanning the age range from preschool to adolescence are presented in conjunction with data from a functional magnetic resonance imaging (fMRI) study of spatial processing. The activation results provide evidence that alternative profiles of neural organization can arise following early focal brain injury, and document where in the brain spatial functions are carried out when regions that normally mediate them are damaged. In addition, the coupling of the activation with the behavioral data allows us to go beyond the simple mapping of functional sites, to ask questions about how those sites may have come to mediate the spatial functions.  相似文献   
104.
Information on the growth of contemporary Native American adolescents is limited. A few studies have shown that Native Americans have growth patterns that may differ from U.S. reference values. We describe basic anthropometric characteristics (height and weight) of Mohawk youth between the ages of 10.0 and 16.99 years from the Akwesasne Mohawk Nation. Body mass index (BMI) was calculated. Mean height of Akwesasne Mohawk youth approximates the 50th percentile of reference values as determined by the 2000 Center for Disease Control and Prevention (CDC) growth charts. At every age, weight means of males approximate or exceed the 90th percentile and all mean weights of females approximate the 85th percentile. Akwesasne males are significantly taller than females from age 14 on and significantly heavier at ages 14 and 16. All age-specific BMI means for males are at or above the 90th percentile and females' means are at or above the 85th. The potential for long-term health effects associated with being overweight has implications for the future health of young Native Americans.  相似文献   
105.
Recent proposals to join spirituality and medicine are facile and ill defined. The notion that physicians have the time or training to make assessments and recommendations about spirituality is misguided. Whenever a physician demonstrates personal caring for a patient, the healing process is likely enhanced, and in that sense, physicians often promote the spirituality of the patient. However, recent proposals to extend the physician’s task to that of assessing religion and directing the patient toward approved forms of spirituality are inappropriate. The languages of religion and science are radically different. The cultural body-mind split will not be solved by such simplistic solutions as having physicians endorse spirituality, which will result only in denigration of both medicine and religion. Physicians are encouraged to rely on clinically trained ministers for assistance in understanding the patient’s state of mind or spirit and its possible effects on the course of illness and health.  相似文献   
106.
107.
A method for dynamic imaging in MRI is presented that enables the acquisition of a series of images with both high temporal and high spatial resolution. The technique, which is based on the projection reconstruction (PR) imaging scheme, utilizes distinct data acquisition and reconstruction strategies to achieve this simultaneous capability. First, during acquisition, data are collected in multiple undersampled passes, with the view angles interleaved in such a way that those of subsequent passes bisect the views of earlier ones. During reconstruction, these views are weighted according to a previously described k-space weighted image contrast (KWIC) technique that enables the manipulation of image contrast by selective filtering. Unlike conventional undersampled PR methods, the proposed dynamic KWIC technique does not suffer from low image SNR or image degradation due to streaking artifacts. The effectiveness of dynamic KWIC is demonstrated in both simulations and in vivo, high-resolution, contrast-enhanced imaging of breast lesions.  相似文献   
108.
Separate investigations have suggested that olanzapine, a D4 antagonist, decreases craving after a priming dose of alcohol and that the DRD4 variable number of tandem repeats (VNTR) polymorphism influences the expression of craving after a priming dose of alcohol. The present study tested the hypothesis that olanzapine may be differentially effective at reducing cue-elicited craving based on individual differences in DRD4 VNTR in a sample of heavy social drinkers. Participants were randomly assigned to receive olanzapine (5 mg) or a control medication (cyproheptadine, 4 mg) prior to consuming three alcoholic drinks. Participants completed subjective measures of craving and euphoria after each drink. Participants who were homozygous or heterozygous for the 7 (or longer) repeat allele of the DRD4 VNTR were classified as DRD4 L, while the other participants were classified as DRD4 S. The findings indicated that olanzapine reduces craving for alcohol at baseline for both DRD4 S and DRD4 L individuals, but only reduces craving after exposure to alcohol cues and after a priming dose of alcohol for DRD4 L individuals.  相似文献   
109.
110.
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