全文获取类型
收费全文 | 21583篇 |
免费 | 1897篇 |
国内免费 | 41篇 |
专业分类
耳鼻咽喉 | 191篇 |
儿科学 | 866篇 |
妇产科学 | 620篇 |
基础医学 | 2846篇 |
口腔科学 | 438篇 |
临床医学 | 2601篇 |
内科学 | 3642篇 |
皮肤病学 | 468篇 |
神经病学 | 2557篇 |
特种医学 | 556篇 |
外科学 | 2478篇 |
综合类 | 219篇 |
一般理论 | 14篇 |
预防医学 | 2811篇 |
眼科学 | 247篇 |
药学 | 1292篇 |
1篇 | |
中国医学 | 32篇 |
肿瘤学 | 1642篇 |
出版年
2023年 | 217篇 |
2022年 | 361篇 |
2021年 | 719篇 |
2020年 | 467篇 |
2019年 | 696篇 |
2018年 | 849篇 |
2017年 | 614篇 |
2016年 | 584篇 |
2015年 | 652篇 |
2014年 | 877篇 |
2013年 | 1179篇 |
2012年 | 1639篇 |
2011年 | 1788篇 |
2010年 | 926篇 |
2009年 | 828篇 |
2008年 | 1261篇 |
2007年 | 1257篇 |
2006年 | 1184篇 |
2005年 | 1097篇 |
2004年 | 1020篇 |
2003年 | 890篇 |
2002年 | 822篇 |
2001年 | 313篇 |
2000年 | 274篇 |
1999年 | 261篇 |
1998年 | 149篇 |
1997年 | 125篇 |
1996年 | 129篇 |
1995年 | 98篇 |
1994年 | 109篇 |
1993年 | 87篇 |
1992年 | 152篇 |
1991年 | 156篇 |
1990年 | 144篇 |
1989年 | 135篇 |
1988年 | 114篇 |
1987年 | 120篇 |
1986年 | 86篇 |
1985年 | 88篇 |
1984年 | 83篇 |
1982年 | 53篇 |
1979年 | 59篇 |
1978年 | 54篇 |
1977年 | 51篇 |
1976年 | 55篇 |
1975年 | 67篇 |
1974年 | 59篇 |
1973年 | 57篇 |
1972年 | 59篇 |
1971年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Catherine M. Cahill Melissa J. Green Rajeev Jairam Gin S. Malhi 《Early intervention in psychiatry》2007,1(2):138-149
Aim: This article reviews research centred around juvenile bipolar disorder with particular reference to diagnostic difficulties. Putative deficits are scrutinized with respect to trait likelihood and the roles of neuropsychology and neuroimaging in enhancing our understanding of juvenile bipolar disorder are discussed. Methods: Search terms including childhood, adolescent, youth and juvenile combined with the terms ‘bipolar disorder’, mania, depression and hypomania were used to identify relevant studies in MEDLINE and PsychLit. Results: Over recent years research into this relatively new disorder has increased phenomenally. Key issues within the field include diagnostic specificity, the heritability of the disorder, the impact of comorbidity and the implications of neuropsychological and neuroimaging findings. Conclusion: Despite concerning controversies in literature the diagnosis of bipolar disorder in children and adolescents as compared with adults, promising future research directions include better neurological characterization of the disorder through the application of findings from clinical populations, neuropsychological and neuroimaging research. 相似文献
22.
Melissa A Fudge Martin Kavaliers Klaus-Peter Ossenkopp 《European neuropsychopharmacology》2006,16(4):272-280
The neurosteroid allopregnanolone may increase feeding by altering food palatability; however, it may also increase feeding by reducing anxiety (neophobia). Moreover, it is unclear whether this induced hyperphagia is selective to safe, palatable foods only. Male rats were injected with allopregnanolone 20 min prior to behavioral testing. The taste reactivity test was used to examine possible shifts in the palatability of a 0.3 M sucrose solution. A lickometer was used to monitor intake and licking of either a sucrose or sucrose-quinine solution. Sucrose palatability was not enhanced; however, allopregnanolone significantly increased sucrose intake and licking on Test Day 1 when the solution was novel, but not on Test Day 2 when the solution was familiar. Sucrose-quinine intake was not enhanced. Allopregnanolone-induced hyperphagia is not a result of altered sucrose palatability, but rather reflects a reduction in the neophobia elicited by a novel solution; an effect that further seems to be selective to safe, palatable foods. 相似文献
23.
24.
Noah A Goldman Ellen B Katz Alan S Glenn Richard H Weldon Joan G Jones Uticia Lynch Melissa J Fezzari Carolyn D Runowicz Gary L Goldberg Maureen J Charron 《Modern pathology》2006,19(11):1429-1436
Glucose is provided to cells by a family of glucose transport facilitators known as GLUTs. These transporters are expressed in a tissue specific manner and are overexpressed in many primary tumors of these tissues. Regulation of glucose transport facilitator expression has been demonstrated in endometrial tissue and endometrial adenocarcinoma. The following experiments were conducted to quantify and localize the expression of GLUT1 and GLUT8 in benign endometrium and compare this expression to endometrial cancer. Endometrial tissue samples were obtained from random hysterectomy specimens of patients with benign indications for surgery and endometrial cancer. Immunoblot and immunolocatization studies were performed using GLUT1 and GLUT8 specific antisera. Endometrial samples from 65 women who had undergone hysterectomy were examined (n=38 benign, n=27 malignant). A 44 and a 35.4 kDa immunoreacive species was demonstrated in endometrium and endometrial cancer for GLUT1 and GLUT8, respectively. Upregulation of GLUT1 expression was demonstrated with increasing grade of tumors (P<0.002). GLUT8 expression was increased in all tumor subtypes compared to atrophic endometrium (P<0.001). Apical localization by GLUT1 and GLUT8 was demonstrated in endometrial glands. GLUT1 and GLUT8 demonstrated diffuse intracellular localization in the cancer subtypes. GLUT1 and GLUT8 are expressed in both human endometrium and endometrial cancer. There appears to be a step-wise progression in GLUT1 and GLUT8 expression as tumor histopathology worsens. GLUT1 and GLUT8 may be important markers in tumor differentiation, as well as providing energy to rapidly dividing tumor cells. 相似文献
25.
Gregory C Gray Troy McCarthy Mark G Lebeck David P Schnurr Kevin L Russell Adriana E Kajon Marie L Landry Diane S Leland Gregory A Storch Christine C Ginocchio Christine C Robinson Gail J Demmler Michael A Saubolle Sue C Kehl Rangaraj Selvarangan Melissa B Miller James D Chappell Danielle M Zerr Deanna L Kiska Diane C Halstead Ana W Capuano Sharon F Setterquist Margaret L Chorazy Jeffrey D Dawson Dean D Erdman 《Clinical infectious diseases》2007,45(9):1120-1131
BACKGROUND: Recently, epidemiological and clinical data have revealed important changes with regard to clinical adenovirus infection, including alterations in antigenic presentation, geographical distribution, and virulence of the virus. METHODS: In an effort to better understand the epidemiology of clinical adenovirus infection in the United States, we adopted a new molecular adenovirus typing technique to study clinical adenovirus isolates collected from 22 medical facilities over a 25-month period during 2004-2006. A hexon gene sequence typing method was used to characterize 2237 clinical adenovirus-positive specimens, comparing their sequences with those of the 51 currently recognized prototype human adenovirus strains. In a blinded comparison, this method performed well and was much faster than the classic serologic typing method. RESULTS: Among civilians, the most prevalent adenovirus types were types 3 (prevalence, 34.6%), 2 (24.3%), 1 (17.7%), and 5 (5.3%). Among military trainees, the most prevalent types were types 4 (prevalence, 92.8%), 3 (2.6%), and 21 (2.4%). CONCLUSIONS: For both populations, we observed a statistically significant increasing trend of adenovirus type 21 detection over time. Among adenovirus isolates recovered from specimens from civilians, 50% were associated with hospitalization, 19.6% with a chronic disease condition, 11% with a bone marrow or solid organ transplantation, 7.4% with intensive care unit stay, and 4.2% with a cancer diagnosis. Multivariable risk factor modeling for adenovirus disease severity found that age <7 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4-7.4), chronic disease (OR, 3.6; 95% CI, 2.6-5.1), recent transplantation (OR, 2.7; 95% CI, 1.3-5.2), and adenovirus type 5 (OR, 2.7; 95% CI, 1.5-4.7) or type 21 infection (OR, 7.6; 95% CI, 2.6-22.3) increased the risk of severe disease. 相似文献
26.
I do not think that the title of this book of nearly 300 closelyprinted pages really does it justice, as it might not attractthose anaesthetists, of all grades, for whom it could be anextremely useful addition to the personal library. The bookis written 相似文献
27.
Eric Vivier Antonio J. da Silva Melissa Ackerly Herbert Levine Christopher E. Rudd Paul Anderson 《European journal of immunology》1993,23(8):1872-1876
The CD16: ζ: γ receptor complex allows natural killer (NK) cells to recognize and eliminate antibody-coated target cells. Whereas the ectodomain of CD16 is the receptor for Fcγ domains of immunoglobulins, disulfide-linked homo- and heterodimers composed of ζ and γ are required for the cell surface expression, and signal transduction properties of the complex. Engagement of CD16 activates the tyrosine kinase pathway, which induces the tyrosine phosphorylation of several substrates, including the ζ subunit and the phospholipase C γ-1 and γ-2 isoforms. Here we show that CD 16 stimulation of either peripheral blood NK cells, leukemic NK cells, or Jurkat transformants expressing a CD16:ζ:γ receptor complex, results in the tyrosine phosphorylation of a 70 kDa ζ-associated protein (pp70). Similarly, a 70-kDa ζ-associated phosphoprotein in T cells has been shown to be a tyrosine kinase (ZAP-70). Peptide mapping analysis indicates that the 70-kDa ζ-associated phosphoproteins from T cells and NK cells are structurally indistinguishable. We conclude that the CD16:ζ:γ complex may use a ZAP-70-related non-receptor tyrosine kinase, in the CD16 signaling cascade leading to NK cell activation. 相似文献
28.
F M Barker 《Optometry and vision science》1990,67(6):431-434
The recent public concern regarding sunglass protection from UV energy has sparked a significant debate among those in the research community and industry. This debate grows out of concern for the known effects of UV energy in producing or contributing to eye effects such as keratitis, cataract formation, and retinal damage. The ANSI Z80.3 Standard addresses itself to this issue by setting levels of UV energy that are permitted to be transmitted in various labeling categories for over-the-counter sunlenses. One important issue is that the ANSI Standard does not provide for an absolute block of UV energy in any category of these lenses. Because the technology to provide this sort of total UV block is currently available, it is argued that there should be at least one category of lens that is fully protective in the UV range. 相似文献
29.
30.
A fatal case of penicillin resistant Staphylococcus lugdunensis endocarditis on a native valve damaged by rheumatic fever is described. A retrospective examination of 978 tube coagulase negative staphylococcal blood culture isolates was also performed to determine how often this species is isolated. None of the 978 isolates was identified as S lugdunensis. It is concluded that ornithine decarboxylase production is the only reliable method of identifying this species. 相似文献