全文获取类型
收费全文 | 3494篇 |
免费 | 197篇 |
国内免费 | 41篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 91篇 |
妇产科学 | 56篇 |
基础医学 | 446篇 |
口腔科学 | 123篇 |
临床医学 | 674篇 |
内科学 | 811篇 |
皮肤病学 | 45篇 |
神经病学 | 291篇 |
特种医学 | 179篇 |
外科学 | 279篇 |
综合类 | 49篇 |
一般理论 | 1篇 |
预防医学 | 232篇 |
眼科学 | 30篇 |
药学 | 198篇 |
中国医学 | 4篇 |
肿瘤学 | 203篇 |
出版年
2023年 | 16篇 |
2022年 | 15篇 |
2021年 | 53篇 |
2020年 | 26篇 |
2019年 | 40篇 |
2018年 | 45篇 |
2017年 | 36篇 |
2016年 | 40篇 |
2015年 | 85篇 |
2014年 | 66篇 |
2013年 | 111篇 |
2012年 | 149篇 |
2011年 | 144篇 |
2010年 | 95篇 |
2009年 | 105篇 |
2008年 | 160篇 |
2007年 | 172篇 |
2006年 | 171篇 |
2005年 | 167篇 |
2004年 | 193篇 |
2003年 | 175篇 |
2002年 | 129篇 |
2001年 | 120篇 |
2000年 | 81篇 |
1999年 | 63篇 |
1998年 | 125篇 |
1997年 | 109篇 |
1996年 | 91篇 |
1995年 | 84篇 |
1994年 | 65篇 |
1993年 | 65篇 |
1992年 | 64篇 |
1991年 | 55篇 |
1990年 | 55篇 |
1989年 | 51篇 |
1988年 | 61篇 |
1987年 | 42篇 |
1986年 | 42篇 |
1985年 | 44篇 |
1984年 | 40篇 |
1983年 | 29篇 |
1982年 | 17篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 31篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1974年 | 12篇 |
1969年 | 13篇 |
排序方式: 共有3732条查询结果,搜索用时 15 毫秒
1.
2.
Joke van Welzen Alex M. van Herk Anton L. German 《Macromolecular chemistry and physics.》1987,188(8):1923-1932
The structural behaviour of cobalt(II)phthalocyanine-tetrasodium sulfonate (CoPc(NaSO3)4) ( 1 ), a catalyst used in thiol oxidation, was investigated in the presence of ionenes (poly-quaternary ammonium salts), ( 2 ) using visible light spectroscopy. It was observed that ionenes, which have been shown to promote the catalytic activity, strongly enhance the aggregation of the cobalt complex. No cobalt site isolation occurred up to N+/Co = 105. Furthermore, a stoichiometric CoPc(NaSO3)4/ionene complex appeared to be formed with an N+/Co-ratio of 4:1. This ratio was found to hold for ionenes with M?n varying from 6 100 to 22 000 and charge densities from 0,8 to 1,5. As the charge density was increased, the observed CoPc(NaSO3)4 spectrum was more affected. Experiments with oxygen in alkaline solution revealed that the complex was resistant toward oxygen adduct formation in the presence of ionenes. This phenomenon is discussed in relation to the catalytic activity of the system. 相似文献
3.
Total circulating platelet count and thrombocytogram were examined in 60 tobacco smokers and in 30 nonsmoking normal subjects aged 23-32. The smokers were divided into two subgroups, 30 subjects in each: Group 1 included those with a history of smoking under 5 years and Group 2 those smoking for 5 years and Group 2 those smoking for 6-10 years. The platelet count was found increased in Group 1 smokers at the expense of old, atypical, and involutional forms. In Group 2 smokers the total platelet count and the counts of their differentiation forms were reduced. This evidences the effect of tobacco smoking on circulating platelets, this effect depending on the length of tobacco smoke inhalation. 相似文献
4.
Lawrence S Prince Heather I Dieperink Victor O Okoh German A Fierro-Perez Roger L Lallone 《Developmental dynamics》2005,233(2):553-561
We tested the hypothesis that innate immune signaling in utero could disrupt the structural development of the fetal lung, contributing to the pathogenesis of bronchopulmonary dysplasia. Injection of Escherichia coli lipopolysaccharide (LPS) into the amniotic fluid of E15 BALB/cJ mice increased the luminal volume density of fetal mouse lungs at embryonic day (E) 17 and E18. LPS also increased luminal volume and decreased distal lung branching in fetal mouse lung explants. This effect required NF-kappaB activation and functional Toll-Like Receptor 4. Airway branching may require fibronectin-dependent epithelial-mesenchymal interactions, representing a potential target for innate immune signaling. Anti-fibronectin antibodies and LPS both blocked distal lung branching. By immunofluorescence, fibronectin localized to the clefts between newly formed airways but was restricted to peripheral mesenchymal cells in LPS-exposed explants. These data suggest that LPS may alter the expression pattern of mesenchymal fibronectin, potentially disrupting epithelial-mesenchymal interactions and inhibiting distal airway branching and alveolarization. This mechanism may link innate immune signaling with defects in structural development of the fetal lung. 相似文献
5.
Gina Kearney MSN RN CS AHN-BC JeMe Cioppa-Mosca PT MBA Margaret G. E. Peterson Ph.D C. Ronald MacKenzie MD 《HSS journal》2007,3(2):198-201
In an outpatient rehabilitation setting, both patients’ use and therapists’ knowledge of complementary and alternative medicine
(CAM) varies widely. Based on this observation and a recognition of CAM as an emerging practice area for rehabilitation professionals,
it was felt that a thorough and consistent approach to the education and orientation of physical therapists to the world of
CAM and integrative care was needed. This special interest paper will describe one center’s approach, development, and use
of a unique and comprehensive training manual designed to provide both a structured and standardized approach for educating
physical therapists about CAM and related therapeutic modalities. This innovative teaching tool allows for multiple methods
of content delivery within a multidisciplinary format and can be used for those who practice currently or desire to practice
in an integrative care environment. 相似文献
6.
7.
Inbred mouse strains have different numbers of midbrain dopaminergic neurons; for example, BALB/cJ mice have 20–25% more neurons than CBA/J mice. As the number of cells decrease, for example in Parkinson's disease and in animals with midbrain dopaminergic cell lesions, the activity of their remaining cells increases. The purpose of the present experiment was to determine whether the functional properties of dopaminergic neurons in the ventral tegmental area (nucleus A10) differ in inbred mouse strains which possess different numbers of cells. The firing rate and autoreceptor sensitivity of A10 dopaminergic cells were examined in the in vitro slice preparation in BALB/cJ, C3H/HeJ, CBA/J, and DBA/2J mouse strains. It was observed that the autoreceptors on mouse dopaminergic neurons exhibit pharmacological properties of dopamine autoreceptors; activation of the autoreceptor produced a marked inhibition (50–70%) in cell firing rate by quinpirole (10−8 M), LY-141865 (10−7 M), (+)-3-(3-hydroxyphenyl)-N-n-propyl-piperidine (10−6 M), propyl-norapomorphine (10−5 M) and dopamine (10−4 M), and this inhibition was blocked or reversed by specific dopamine D2 receptor antagonists [(−) sulphide and spiroperidol, 10−6 M]. The baseline firing rates of the A10 cells did not differ among the four inbred strains [range 2.5 ± 0.2 (C3H/HeJ)−3.4 ± 0.3 (CBA/J) spikes/s ±SEM], and there was no significant difference in autoreceptor sensitivity among the mouse strains as assessed either by superfused dopamine (inhibitory dose 50% ≈150 μM), or by superfused quinpirole (inhibitory dose 50% ≈10 nM). These data indicate that differences in A10 cell numbers of 30% do not significantly influence the baseline firing rate or autoreceptor sensitivity of the cells. 相似文献
8.
Daniel B. Costa Christopher A. Fisher Kenneth B. Miller German A. Pihan David P. Steensma Richard J. Gibbons Douglas R. Higgs 《European journal of haematology》2006,76(5):432-435
Abstract: We describe a patient with acquired alpha-thalassemia myelodysplastic syndrome (ATMDS). A previously healthy 66-year-old man presented with hemoglobin of 9.3 g/dL, mean corpuscular volume 59 fL, and a bone marrow aspirate with increased erythroid precursors and hypolobulated megakaryocytes. Hemoglobin H inclusions were seen in most red cells after 1% brilliant cresyl blue supravital stain of the peripheral blood. At the molecular level, we identified of a novel mutation in the most 3' exon of the ATRX gene ( C GA→ T GA substitution in codon 2407) resulting in a premature termination codon (p.R2407X). This case provides further evidence for a link between ATRX mutations and ATMDS, and suggests a possible role for the conserved Q-box element in ATRX function. 相似文献
9.