全文获取类型
收费全文 | 25904篇 |
免费 | 2706篇 |
国内免费 | 107篇 |
专业分类
耳鼻咽喉 | 214篇 |
儿科学 | 932篇 |
妇产科学 | 739篇 |
基础医学 | 3624篇 |
口腔科学 | 386篇 |
临床医学 | 3707篇 |
内科学 | 5656篇 |
皮肤病学 | 590篇 |
神经病学 | 2642篇 |
特种医学 | 630篇 |
外国民族医学 | 5篇 |
外科学 | 2746篇 |
综合类 | 214篇 |
一般理论 | 5篇 |
预防医学 | 2496篇 |
眼科学 | 315篇 |
药学 | 1745篇 |
中国医学 | 19篇 |
肿瘤学 | 2052篇 |
出版年
2023年 | 253篇 |
2022年 | 394篇 |
2021年 | 797篇 |
2020年 | 618篇 |
2019年 | 944篇 |
2018年 | 1050篇 |
2017年 | 810篇 |
2016年 | 864篇 |
2015年 | 903篇 |
2014年 | 1130篇 |
2013年 | 1543篇 |
2012年 | 1972篇 |
2011年 | 1861篇 |
2010年 | 1168篇 |
2009年 | 1057篇 |
2008年 | 1580篇 |
2007年 | 1582篇 |
2006年 | 1449篇 |
2005年 | 1359篇 |
2004年 | 1264篇 |
2003年 | 1161篇 |
2002年 | 1070篇 |
2001年 | 292篇 |
2000年 | 280篇 |
1999年 | 272篇 |
1998年 | 265篇 |
1997年 | 202篇 |
1996年 | 162篇 |
1995年 | 161篇 |
1994年 | 136篇 |
1993年 | 113篇 |
1992年 | 128篇 |
1991年 | 133篇 |
1990年 | 119篇 |
1989年 | 118篇 |
1988年 | 102篇 |
1987年 | 88篇 |
1986年 | 91篇 |
1985年 | 87篇 |
1984年 | 80篇 |
1983年 | 82篇 |
1982年 | 84篇 |
1981年 | 80篇 |
1980年 | 52篇 |
1979年 | 54篇 |
1978年 | 57篇 |
1977年 | 61篇 |
1976年 | 65篇 |
1975年 | 68篇 |
1974年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to
evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses.
B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of
suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B
cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM
of the suppressed allotype was initially depleted in mice suppressed for either allotype, by
7 months of age, there were detectable levels of IgM of the suppressed allotype in the
serum; however, the levels were significantly below that found in nonsuppressed mice.
When mice were immunized with either the T-independent or T-dependent form of
phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1
B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the
suppressed allotype. In contrast, when mice were immunized with α1-3 dextran, the Igh6a
allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These
results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed
by this suppression protocol and this produces long-lasting effects on B-1 cell levels and
serum IgM of the suppressed allotype. These observations reflect the derivation of the
majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly
emerging B-2 cells of adult origin. Their ablation by antibody treatment results in
permanent alterations to the adult B-cell repertoire. 相似文献
62.
Marie Biancuzzo 《分娩》1994,21(2):96-100
ABSTRACT: This case report describes a primipara who successfully breastfed 35-week-gestation twins for over six months. Positive interactions, research-based management strategies, and innovative problem solving helped her avoid the individual, interpersonal, and system factors that can injuence lactation failure. (BIRTH 21:2, June 1994) 相似文献
63.
Louise Rose MN Adult Ed Cert BN ICU Cert Dip Nurs Marie F. Gerdtz RN BN AE Cert GDAET PhD 《Australasian emergency nursing journal : AENJ》2007,10(1):26-29
The use of mechanical ventilation in the Emergency Department requires adequate resources in order to maintain patient safety and avoid potential risks. Moreover, developments in technology require increased knowledge of mechanical ventilation techniques to address the complexity of decision-making involved. Organisational issues and system factors have the potential to negatively impact on the ability of the emergency service to provide optimum care to patients receiving mechanical ventilation. These issues include staffing and skill-mix, demand on emergency services, role-delineation, scope of practice, and current mechanisms for monitoring of quality and safety. Furthermore, in response to advances in ventilator technology, current education programs for both nursing and medical staff require review to ensure that they provide comprehensive information about the types of ventilation techniques now available and the relative risks and benefits associated with their application.This article is the second in a two-part series and explores the educational and organisational factors that impact upon safety and quality of care delivered to patients receiving mechanical ventilation in the emergency department. Recommendations for future policy development, curriculum review and reporting mechanisms to support further research in the application of mechanical ventilation in the emergency department are made. 相似文献
64.
R S McElhinney J E McCormick M C Bibby J A Double G Atassi P Dumont G Pratesi M Radacic 《Anti-cancer drug design》1989,4(1):1-20
This study describes the manipulation of secondary products arising from the synthesis of the prototypical molecular combination of 5-fluorouracil (5-FU) and chloroethylnitrosourea (CNU), B.3839, in order to investigate the effects produced by connecting the C-S-C-C-CNU chain to the 5-FU ring in different ways. The isolation of phthalimide precursors of these compounds and the transformation into CNUs is described. Anti-tumour activity of these molecular combinations against a series of experimental murine colon, lung and mammary tumours is presented. The spectrum of anti-tumour activity displayed is interesting but defies simple explanation without further detailed in vivo pharmacokinetic and metabolism studies in order to define optimal profiles for activity. 相似文献
65.
66.
C. Noonan M. Farrell J. Mullaney H. Cassidy M. A. Asghar B. J. Young Marie Hickey-Dwyer A. Patterson W. Power M. Hillery A. Benedict-Smith L. M. T. Collum S. Fitzsimon E. O’Donoghue R. Hitchings G. B. Arden A. O’Mahony A. Murray A. Whyte M. Shehata Hugh O’Donoghue Rosemary Robinson J. Toland P. Eustace 《Irish journal of medical science》1991,160(10):322-324
67.
68.
69.
70.
Brian F O'Donnell Marcia A Wilt Ann Marie Hake Julie C Stout Sandra C Kirkwood Tatiana Foroud 《Movement disorders》2003,18(9):1027-1034
Disturbances of visual cognition, visuomotor performance, and visual memory have been described frequently in Huntington's disease (HD). Early stage visual abnormalities could contribute to these deficits. We evaluated visual processing in 20 control subjects who were non-gene carriers at risk for HD, nine presymptomatic gene-positive subjects, and eight subjects with a recent diagnosis of Huntington's disease. Visual perceptual tests of contrast sensitivity and motion discrimination were used to probe early stage visual processing. Extraocular movements were evaluated in a neurologic examination, and the Digit Symbol test was used to test visual motor performance. Contrast sensitivity did not differ among the three groups. Motion discrimination was impaired in HD subjects but not in the presymptomatic gene carriers when compared to gene noncarriers. Among gene carriers, impaired motion discrimination performance was associated with poorer Digit Symbol performance and extraocular abnormalities. These findings suggest that the early stages of HD are associated with disturbances of motion perception as well as disruptions of visual motor and ocular motor performance. 相似文献