全文获取类型
收费全文 | 5839篇 |
免费 | 458篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 143篇 |
妇产科学 | 156篇 |
基础医学 | 836篇 |
口腔科学 | 127篇 |
临床医学 | 535篇 |
内科学 | 1226篇 |
皮肤病学 | 93篇 |
神经病学 | 551篇 |
特种医学 | 211篇 |
外科学 | 617篇 |
综合类 | 128篇 |
一般理论 | 4篇 |
预防医学 | 666篇 |
眼科学 | 224篇 |
药学 | 361篇 |
中国医学 | 13篇 |
肿瘤学 | 368篇 |
出版年
2021年 | 92篇 |
2020年 | 52篇 |
2019年 | 85篇 |
2018年 | 97篇 |
2017年 | 74篇 |
2016年 | 66篇 |
2015年 | 74篇 |
2014年 | 112篇 |
2013年 | 185篇 |
2012年 | 239篇 |
2011年 | 280篇 |
2010年 | 172篇 |
2009年 | 159篇 |
2008年 | 229篇 |
2007年 | 243篇 |
2006年 | 269篇 |
2005年 | 290篇 |
2004年 | 285篇 |
2003年 | 272篇 |
2002年 | 237篇 |
2001年 | 168篇 |
2000年 | 165篇 |
1999年 | 152篇 |
1998年 | 79篇 |
1997年 | 68篇 |
1996年 | 62篇 |
1995年 | 61篇 |
1994年 | 72篇 |
1993年 | 72篇 |
1992年 | 110篇 |
1991年 | 119篇 |
1990年 | 109篇 |
1989年 | 97篇 |
1988年 | 103篇 |
1987年 | 103篇 |
1986年 | 100篇 |
1985年 | 78篇 |
1984年 | 71篇 |
1983年 | 58篇 |
1982年 | 57篇 |
1981年 | 52篇 |
1980年 | 67篇 |
1979年 | 57篇 |
1978年 | 68篇 |
1977年 | 65篇 |
1976年 | 52篇 |
1974年 | 55篇 |
1973年 | 49篇 |
1972年 | 40篇 |
1971年 | 34篇 |
排序方式: 共有6316条查询结果,搜索用时 15 毫秒
81.
82.
Hall AJ Engelhard GH Brasseur SM Vecchione A Burton HR Reijnders PJ 《Developmental and comparative immunology》2003,27(6-7):629-637
The 'immunocompetence handicap hypothesis' predicts that highly sexually dimorphic and polygynous species will exhibit sex differences in immunity. We tested this hypothesis in southern elephant and grey seals during their early development by measuring the following parameters: leucocyte counts, serum IgG levels, erythrocyte sedimentation rate and haematocrit. We failed to find any differences due to sex as assessed by the parameters investigated. Animals were sampled longitudinally during their development and there were significant age effects from birth to weaning in both species. Total and differential leucocyte counts and erythrocyte sedimentation rates increased just prior to weaning then decreased. Haematocrits declined whilst total circulating immunoglobulin G concentrations increased. Body temperatures remained constant throughout the postnatal period. Differences between the species were seen in total leucocyte counts and in polymorphonuclear cells and eosinophils. Southern elephant seals had higher concentrations than grey seals and total leucocyte counts in the former were among the highest reported for mammals. 相似文献
83.
84.
Williams EJ Gleeson D Burton JL Stephenson TJ 《European journal of gastroenterology & hepatology》2003,15(1):91-93
Kayser-Fleischer rings are brown pigmented rings that run along the periphery of the cornea. Situated in Descemet's membrane and being comprised of granules of deposited copper they have traditionally been thought of as pathognomic of Wilson's disease. However, they can also be seen in other forms of liver disease. We document a case of Kayser-Fleischer like rings occurring in alcoholic liver disease--a previously unreported association. 相似文献
85.
Zweiman B 《Current allergy and asthma reports》2003,3(6):455-457
Conclusions As is evident from the foregoing discussion in this article, there is increasing evidence that a particular type of autoimmune
reaction, directed against the Fc-epsilon RI, and less commonly against IgE, might be pathogenic in many cases of apparent
CIU. The stimulus for this autoimmune response is currently unknown. Most of the evidence for an association of CU with certain
systemic diseases is circumstantial, based on epidemiologic findings of an associated prevalence and possibly on the results
of therapy directed at the systemic condition. If such associations truly occur, the underlying pathogenic mechanisms are
obscure. Hopefully, further investigation will elucidate these relationships and possibly aid in the understanding of the
pathogenesis of CIU itself. 相似文献
86.
87.
Greenwold N Jauniaux E Gulbis B Hempstock J Gervy C Burton GJ 《Fertility and sterility》2003,79(6):1373-1379
OBJECTIVE: To evaluate the relationship among maternal serum endocrinology, placental karyotype, and intervillous blood flow in missed miscarriage. DESIGN: Cross-sectional study of maternal serum, transvaginal ultrasound/Doppler, and placental cytogenetic and immunohistochemical investigations. SETTING: Tertiary care academic hospital. PATIENT(S): One hundred fifty-two women with missed miscarriage between 7 and 13 weeks of gestation. INTERVENTION(S): Ultrasound features, placental intervillous circulation findings on color Doppler imaging, and maternal serum level of alpha-fetoprotein (AFP), beta-hCG, E(2), P, and inhibin A were compared retrospectively with placenta karyotype and hCG immunochemistry. MAIN OUTCOME MEASURES: Data were analyzed according to karyotype results, presence or absence of an intervillous circulation, and delay between fetal demise and evacuation. RESULT(S): The presence of intervillous blood flow and serum concentrations of the different hormones were independent of placental karyotype. Serum beta-hCG and P were significantly higher in cases with intervillous blood flow. No difference in immunostaining for beta-hCG was found between placental tissues from normal pregnancies and missed miscarriages, but significantly higher villous beta-hCG content was found on Western blotting in miscarriage with a recent fetal demise. CONCLUSION(S): The excessive entry of maternal blood inside the placenta in the early stage of most miscarriages is unrelated to conceptus karyotype, and hCG features may reflect a temporary attempt of the trophoblast to stabilize after the initial oxidative insult. 相似文献
88.
Schweinberger SR Burton AM 《Cortex; a journal devoted to the study of the nervous system and behavior》2003,39(1):9-30
In this viewpoint, we discuss the new evidence on covert face recognition in prosopagnosia presented by Bobes et al. (2003, this issue) and by Sperber and Spinnler (2003, this issue). Contrary to earlier hypotheses, both papers agree that covert and overt face recognition are based on the same mechanism. In line with this suggestion, an analysis of reported cases with prosopagnosia indicates that a degree of successful encoding of facial representations is a prerequisite for covert recognition to occur. While we agree with this general conclusion as far as Bobes et al.'s and Sperber and Spinnler's data are concerned, we also discuss evidence for a dissociation between different measures of covert recognition. Specifically, studies in patients with Capgras delusion and patients with prosopagnosia suggest that skin conductance and behavioural indexes of covert face recognition are mediated by partially different mechanisms. We also discuss implications of the new data for models of normal face recognition that have been successful in simulating covert recognition phenomena (e.g., Young and Burton, 1999, and O'Reilly et al., 1999). Finally, in reviewing recent neurophysiological and brain imaging evidence concerning the neural system for face processing, we argue that the relationship between ERP components (specifically, N170, N250r, and N400) and different cognitive processes in face recognition is beginning to emerge. 相似文献
89.
To examine the relationship between cognitive impairment and desire for death in patients with advanced AIDS we evaluated 128 patients with advanced AIDS consecutively admitted to three long-term care facilities. Participants completed a clinical assessment that included a self-report measure of desire for hastened death in the medically ill (Schedule of Attitudes toward Hastened Death), three measures of cognitive functioning designed to screen for cognitive impairment (Dementia Rating Scale, Mini-Mental State Exam, HIV Dementia Scale), and other measures of physical and psychological functioning. Participants who were classified as cognitively impaired obtained significantly higher scores on the measure of desire for death than did patients without cognitive impairment. This modest association between cognitive impairment and desire for death remained significant even after controlling for the impact of depression on desire for death. Specific aspect of cognitive functioning such as memory and psychomotor coordination appeared to be more salient than executive functioning or abstract reasoning. Cognitive impairment appears to have a modest, but significant impact on patients' desire for hastened death. Aggressive treatment of cognitive symptoms in the terminally ill is necessary in order to disentangle the various factors that may drive end-of-life treatment decisions. 相似文献
90.
We hypothesized that a prior history of a major depressive disorder would not compromise the efficacy of percutaneous transluminal coronary angioplasty (PTCA), a coronary revascularization procedure, in improving quality of life and health status when comparing patients with no previous history. To determine the utility of screening for risk for depression in heart patients scheduled for PTCA, 190 patients were administered a two-item depressive disorders screener prior to PTCA and the SF-36 and Seattle Angina Questionnaire prior to and 6 months post procedure. Results reveal that while those with no prior history of depression had statistically better quality of life and health status outcomes than those with a probable past depression, (P <.05), the clinically meaningful differences as determined by effect size scores showed that those susceptible to recurrent depression benefited from PTCA as well as, and on some measures better than those with no previous history. Prescreening patients at probable risk for a depression is not a valid or helpful enterprise if the purpose is to develop intervention strategies for improving outcome post PTCA. Screening out patients based on history of depression may in fact lead to an inequitable allocation of resources and have no major benefit in enhancing quality of life and improving health status. 相似文献