全文获取类型
收费全文 | 8295篇 |
免费 | 638篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 80篇 |
儿科学 | 284篇 |
妇产科学 | 147篇 |
基础医学 | 1448篇 |
口腔科学 | 296篇 |
临床医学 | 700篇 |
内科学 | 1729篇 |
皮肤病学 | 93篇 |
神经病学 | 496篇 |
特种医学 | 442篇 |
外科学 | 1201篇 |
综合类 | 51篇 |
一般理论 | 2篇 |
预防医学 | 567篇 |
眼科学 | 61篇 |
药学 | 841篇 |
中国医学 | 9篇 |
肿瘤学 | 507篇 |
出版年
2022年 | 49篇 |
2021年 | 85篇 |
2020年 | 76篇 |
2019年 | 90篇 |
2018年 | 125篇 |
2017年 | 131篇 |
2016年 | 103篇 |
2015年 | 137篇 |
2014年 | 173篇 |
2013年 | 272篇 |
2012年 | 349篇 |
2011年 | 370篇 |
2010年 | 242篇 |
2009年 | 233篇 |
2008年 | 344篇 |
2007年 | 344篇 |
2006年 | 356篇 |
2005年 | 311篇 |
2004年 | 287篇 |
2003年 | 295篇 |
2002年 | 281篇 |
2001年 | 256篇 |
2000年 | 304篇 |
1999年 | 266篇 |
1998年 | 144篇 |
1997年 | 158篇 |
1996年 | 115篇 |
1995年 | 128篇 |
1994年 | 126篇 |
1993年 | 118篇 |
1992年 | 229篇 |
1991年 | 217篇 |
1990年 | 219篇 |
1989年 | 224篇 |
1988年 | 188篇 |
1987年 | 202篇 |
1986年 | 171篇 |
1985年 | 145篇 |
1984年 | 125篇 |
1983年 | 121篇 |
1982年 | 83篇 |
1981年 | 73篇 |
1980年 | 66篇 |
1979年 | 91篇 |
1978年 | 86篇 |
1977年 | 65篇 |
1976年 | 49篇 |
1975年 | 52篇 |
1974年 | 52篇 |
1973年 | 42篇 |
排序方式: 共有8954条查询结果,搜索用时 15 毫秒
81.
Suppression of macrophage activation with CNI-1493 increases survival in infant rats with systemic Haemophilus influenzae infection 总被引:1,自引:0,他引:1 下载免费PDF全文
Granert C Abdalla H Lindquist L Diab A Bahkiet M Tracey KJ Andersson J 《Infection and immunity》2000,68(9):5329-5334
CNI-1493, a potent macrophage deactivator, was used to treat infant rats systemically infected with Haemophilus influenzae type b (Hib). CNI-1493 was injected 1 h prior to bacterial inoculation and 24 h later and resulted in a 75 percent increased rate of survival compared to that for untreated controls. The effect of CNI-1493 on the inflammatory response was studied by immunohistochemical detection of individual tumor necrosis factor alpha (TNF-alpha)-, interleukin 1 beta (IL-1beta)-, and gamma interferon (IFN-gamma)-producing cells in the spleen. A significant reduction of the incidence of TNF-alpha- and IL-1beta-expressing cells was found for CNI-1493-treated animals. IFN-gamma expression was not suppressed by CNI-1493, indicating that cytokine inhibition was specific in macrophages. CNI-1493 significantly reduced the number of infiltrating granulocytes in the brain from that for controls. This study provides evidence that CNI-1493 protects against lethal Hib infection by deactivating the inflammatory cascade in infant rats. 相似文献
82.
S. E. Andersson L. Källström M. Malm A. Miller-Larsson B. Axelsson 《Inflammation research》1995,44(10):418-422
In the present study we have investigated the effect of L-nitro arginine mono methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase on Sephadex induced inflammation in the rat lung. Instillation of Sephadex into the airways induced an inflammatory reaction characterized by a long-lasting interstitial oedema, measured as an increase in lung weight, and an influx of inflammatory cells into the airways. L-NAME given s.c. prevented the increase in lung weight following Sephadex instillation. The inactive enantiomer D-NAME had no effect, nor did aminoguanidine which indicates that this effect of L-NAME was mediated by inhibition of the constitutive form of NOS. Treatment with L-NAME did not reduce an established oedema. In contrast, L-NAME tended to enhance the influx of oesinophils into the airways of Sephadex-instilled animals.L-NAME did not have any effect on the development of oedema in adrenalectomized rats or in animals where formation of glucocorticosteroids (GCS) was inhibited with metyrapone. L-NAME did not however, increase plasma levels of corticosterone. The present results indicate that, in this model, inhibition of NO-synthesis has marked anti-inflammatory effects. The underlying mechanism is complex but seems not to involve prevention of overproduction of NO. 相似文献
83.
Culture of pancreatic islets isolated from obese-hyperglycemic mice (gene symbol ob) for one week in media containing widely different concentrations of glucose (3.3, 5.6 or 16.7 mM) was found to markedly influence the functional behaviour of the islet B-cells. Thus, the insulin content of islets cultured at 3.3 or 16.7 mM glucose (subphysiological or supraphysiological glucose concentrations respectively) was markedly reduced. Islets cultured in 5.6 or 16.7 mM glucose displayed a normal insulin secretory response when stimulated with glucose, whereas islets cultured in a subnormal glucose concentration (3.3 mM) showed a reduced insulin response to glucose stimulation in batch type incubations and also lacked a second phase of insulin secretion in islet perifusion experiments. The rate of insulin biosynthesis of non-cultured ob/ob islets was higher than that of islets from their lean siblings but culture for one week in 3.3 mM glucose induced a pronounced impairment of the insulin biosynthesis in islets of obese as well as lean mice. The present data indicate that the hyperfunction of the islets of the ob/ob mouse at least in part is a reversible phenomenon, suggesting that inherent properties of islet B-cells do not act as "primary" factors in the development of the obese-hyperglycemic syndrome. 相似文献
84.
Agneta Johansson Eva Särndahl Tommy Andersson Torbjörn Bengtsson Helen Lundqvist Claes Dahlgren 《Inflammation》1995,19(2):179-191
When the chemotactic peptide formylmethionyl-leucyl-phenylalanine binds to its cell surface receptor, a transmembrane signal is generated that activates the superoxide-producing NADPH oxidase of human phagocytes. Comparing monocytes and neutrophils with regard to the production of superoxide anion induced by the peptide, we found a similar time-course for both types of cells. In neutrophils, ligand binding induced a conversion of the receptor to a high-affinity form, a change suggested to be due to an association of the receptor-ligand complex to the Triton X-100-insoluble cytoskeleton. This event has been hypothesized to terminate the signal that activates the NADPH oxidase and thereby results in cessation of the cellular production of superoxide anion. Neutrophils preincubated with the cytoskeleton-disrupting drug cytochalasin B showed an increased and prolonged superoxide anion production after activation with the peptide, thus indicating that the cytoskeleton is involved in terminating this response. Formylmethionyl-leucyl-phenylalanine was also found to induce polymerization of actin in monocytes; however, cytochalasin B had no effect on the peptide-induced generation of superoxide anion in these cells. Furthermore, also in monocytes, ligand binding induced a conversion of the receptor to a high-affinity form; however, the receptor-ligand complex did not coisolate with the Triton X-100-insoluble cytoskeleton. These results indicate that, in monocytes, the NADPH oxidase activating pathway is terminated without any association of the receptor-ligand complex to the Triton X-100-insoluble cytoskeleton. 相似文献
85.
Expression of interleukin-1 alpha, interleukin-1 beta and interleukin-6 in chronic B lymphocytic leukaemia (B-CLL) cells from patients at different stages of disease progression. 下载免费PDF全文
M Aguilar-Santelises R Magnusson S B Svenson A Loftenius B Andersson H Mellstedt M Jondal 《Clinical and experimental immunology》1991,84(3):422-428
We have previously found that isolated B-CLL cells from progressive disease produce less interleukin-1 beta (IL-1 beta) as compared with cells from patients with indolent disease. Here we extend that finding to include measurements of IL-1 beta mRNA and secretion of IL-1 alpha and interleukin-6 (IL-6). As before, a lower production of IL-1 beta was found in cells from progressive disease. IL-6 was produced by cells from patients at all stages, with a tendency to follow the IL-1 beta production. Low secretion of IL-1 alpha was noted. When viable cells were permeabilized and analysed at the single cell level with monoclonal antibodies, most B-CLL cells were found to contain IL-1 alpha. A minor fraction of non-permeabilized cells expressed IL-1 alpha at the cell membrane. However, only small fractions of cells were positive for intracellular IL-1 beta (less than 1%) and almost no IL-6-positive cells were found. We conclude that either IL-1 beta and IL-6 are produced by a minor population of undefined cells, or that a more sensitive in situ method is needed to detect production of these cytokines in B-CLL cells. The possible biological significance of secreted, and membrane-expressed helper factors in B-CLL is discussed. 相似文献
86.
Transcriptional regulation of HLA class-II genes 总被引:5,自引:0,他引:5
87.
Dissection of the human antibody response to the malaria antigen Pf155/RESA into epitope specific components 总被引:18,自引:0,他引:18
88.
A persistent T cell expansion in the peripheral blood of a normal adult male: a new clinical entity? 下载免费PDF全文
J Grunewald M Jeddi-Tehrani H Dersimonian R Andersson H Wigzell 《Clinical and experimental immunology》1992,89(2):279-284
A dramatic and persistent T cell expansion in a healthy adult male was initially identified, using anti-T cell receptor for antigen (TCR)-specific MoAbs. The expanded T cells were found to be expressing TCR containing V alpha 12.1 and V beta 5.2, and they composed approximately one third of all the CD8+ T cells. The cells were shown to be not only non-activated (HLA-DR-, IL-2R-) but also of 'virgin' cell type (CD45RA+/CD45RO-) and they persisted over the observation period of more than one and a half years. Various T and B cell markers, and all other laboratory and physical parameters analysed, were normal. The expanded CD8+ T cells were further characterized by polymerase chain reaction (PCR) amplification, using V beta- and C beta-specific primers, followed by hybridization with J beta-specific probes. Close to 90% of the V alpha 12.1+ V beta 5.2+ T cells were found to utilize the J beta 2.5 gene segment, thus strongly suggesting the expanded T cells to be monoclonal. The condition may constitute a T cell counterpart to 'monoclonal gammopathy of undetermined significance' (MGUS), and by analogy we suggest it should be designated 'monoclonal T cell expansion of undetermined significance' (MTUS). 相似文献
89.
G Kapperud L M Rrvik V Hasseltvedt E A Hiby B G Iversen K Staveland G Johnsen J Leitao H Herikstad Y Andersson 《Journal of clinical microbiology》1995,33(3):609-614
In the period from May through June 1994, an increase in the number of domestic cases of Shigella sonnei infection was detected in several European countries, including Norway, Sweden, and the United Kingdom. In all three countries epidemiological evidence incriminated imported iceberg lettuce of Spanish origin as the vehicle of transmission. The outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enteropathogens, and the finding of two dominant phage types among the bacterial isolates. In Norway 110 culture-confirmed cases of infection were recorded; more than two-thirds (73%) were adults aged 30 to 60 years. A nationwide case-control study comprising 47 case patients and 155 matched control individuals showed that the consumption of imported iceberg lettuce was independently associated with an increased risk of shigellosis. Epidemiological investigation of a local outbreak incriminated iceberg lettuce from Spain, consumed from a salad bar, as the source. The presence of shigellae in the suspected food source could not be documented retrospectively. However, high numbers of fecal coliforms were detected in iceberg lettuce from patients' homes. Three lettuce specimens yielded salmonellae. The imported iceberg lettuce harbored Escherichia coli strains showing resistance to several antimicrobial agents, including ampicillin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole. During the outbreak it is likely that thousands of Norwegians and an unknown number of consumers in other countries were exposed to coliforms containing antibiotic resistance genes. 相似文献
90.
Telfer JF; Thomson AJ; Cameron IT; Greer IA; Norman JE 《Human reproduction (Oxford, England)》1997,12(10):2306-2312
Superoxide, an agent which attenuates the half-life of nitric oxide, is
metabolized and synthesized by superoxide dismutase (SOD) and xanthine
oxidase, respectively. Over the last few years much work has focused on the
role of nitric oxide in human parturition. The aim of this study was to
determine whether the onset of human parturition is associated with a
change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD),
manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the
uterus. Samples of myometrium, placenta, decidua and fetal membranes were
obtained from women before and after the onset of labour at term.
Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine
oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like
immunoreactivity was detected in syncytiotrophoblast cells, villous stromal
cells and endothelial cells of blood vessels in the placenta. In the
myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial
cells and to some vascular smooth muscle cells. In the fetal membranes we
observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion,
extravillous trophoblast and decidua. There was no difference in SOD enzyme
activity or staining intensity for SOD between different cell types before
and during labour. Xanthine oxidase immunoreactivity was identified in each
of the tissues examined and again there was no difference in immunostaining
in tissues obtained from women delivered before or after the onset of
labour. These results show that the pregnant uterus is capable of both
synthesizing and degrading superoxide and suggest that superoxide dismutase
and xanthine oxidase may play a role in the maintenance of uterine
quiescence during pregnancy, but not in the initiation of parturition.
相似文献