全文获取类型
收费全文 | 14740篇 |
免费 | 799篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 287篇 |
儿科学 | 391篇 |
妇产科学 | 470篇 |
基础医学 | 2053篇 |
口腔科学 | 1108篇 |
临床医学 | 893篇 |
内科学 | 3273篇 |
皮肤病学 | 519篇 |
神经病学 | 1302篇 |
特种医学 | 408篇 |
外科学 | 2235篇 |
综合类 | 55篇 |
一般理论 | 3篇 |
预防医学 | 928篇 |
眼科学 | 193篇 |
药学 | 759篇 |
中国医学 | 77篇 |
肿瘤学 | 645篇 |
出版年
2023年 | 110篇 |
2022年 | 313篇 |
2021年 | 513篇 |
2020年 | 354篇 |
2019年 | 418篇 |
2018年 | 506篇 |
2017年 | 354篇 |
2016年 | 370篇 |
2015年 | 471篇 |
2014年 | 654篇 |
2013年 | 744篇 |
2012年 | 1147篇 |
2011年 | 1227篇 |
2010年 | 738篇 |
2009年 | 629篇 |
2008年 | 1044篇 |
2007年 | 1018篇 |
2006年 | 978篇 |
2005年 | 954篇 |
2004年 | 729篇 |
2003年 | 646篇 |
2002年 | 582篇 |
2001年 | 72篇 |
2000年 | 53篇 |
1999年 | 85篇 |
1998年 | 101篇 |
1997年 | 111篇 |
1996年 | 81篇 |
1995年 | 83篇 |
1994年 | 58篇 |
1993年 | 61篇 |
1992年 | 33篇 |
1991年 | 36篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 29篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 11篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 20篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
John B. Davies Ricardo Luján Luis A. López-Martinez Aura J. Paniagua-Alvarez Byron E. Morales-Hernández K. Sherlock 《Tropical medicine & international health : TM & IH》1997,2(4):348-355
Summary Since 1992, efforts have been made to combat onchocerciasis in Guatemala through mass distribution of ivermectin. The impact of the campaign is assessed by taking skin-snips from sentinel groups within selected communities. This method gives an estimate of the prevalence and intensity of infection, and thus the efficacy of the treatment. In some communities people are becoming reluctant to volunteer for skin-snipping, and so there is a need for an alternative technique that will give quantitative results. In most hyperendemic communities in Guatemala, biting blackflies are so ubiquitous that few people object to allowing 10 to 20 flies to engorge upon them. We examined data on the quantitative uptake of microfilariae by Simulium ochraceum before and after ivermectin distribution to see whether results similar to skin-snip data could be obtained. Counts of microfilariae ingested by S. ochraceum are compared to the numbers found in skin-snips from the same volunteers. In a group of 31 untreated infected persons, a skin-snip survey detected 64.5% positive, while feeding flies (vector microfilarial uptake, VmfU) detected 96.8%. Post-treatment, in a sample of 58 of whom 52 (89.7%) had a history of infection, both skin-snips and VmfU detected 54.2%. Vector blood meals contained more microfilariae than a mg of skin before treatment, but both recorded about equal numbers after treatment. When the data set was subdivided to compare samples taken at 2–3, 6–8 and 14–17 months post-treatment, the effect of ivermectin was still apparent at 6–8 months, but had virtually disappeared by 14 months post-treatment. A surprising observation was that the flies ingested fewer microfilariae from treated persons than was expected from the skin densities as estimated by skin-snip. This effect lasted for over 8 months, and could indicate that ivermectin has a greater effect on transmission than previously suspected. We conclude that VmfU could be used as an alternative to skin-snipping, and discuss the ethical implications. 相似文献
62.
Romina Mizrahi Sergio E Starkstein Ricardo Jorge Robert G Robinson 《The American journal of geriatric psychiatry》2006,14(7):573-581
OBJECTIVES: The objectives of this study were to determine whether anosognosia, depression, and elevated mood are associated with delusions in Alzheimer disease (AD), and to examine the validity of standardized diagnostic criteria for psychosis of dementia. METHOD: The authors assessed a consecutive series of 771 patients with AD attending a dementia clinic with a comprehensive neuropsychologic and psychiatric evaluation that included specific measures of delusions, hallucinations, anosognosia, depression, and elevated mood. RESULTS: Delusions were found in one-third of the patients and hallucinations in 7%. Most patients with hallucinations also had delusions. A principal component analysis of the Psychosis Dementia Scale, which rates the presence and severity of delusions, produced the factors of paranoid misidentification and expansive delusions. Paranoid, but not expansive, delusions increased across the stages of the illness. Anosognosia and depression were significantly and independently associated with the presence of delusions, whereas elevated mood was significantly associated with expansive, but not paranoid, delusions. A multiple logistic regression analysis demonstrated that delusions in AD were significantly associated with depression, anosognosia, overt aggression, and agitation. CONCLUSIONS: Anosognosia, depression, global cognitive deficits, and elevated mood are the main psychiatric correlates of paranoid misidentification and expansive delusions in AD, whereas overt aggression and agitation are the most frequent behavioral concomitants of psychosis in AD. 相似文献
63.
64.
Immune reactions associated with silicone-based ventriculo-peritoneal shunt malfunctions in children
VandeVord PJ Gupta N Wilson RB Vinuya RZ Schaefer CJ Canady AI Wooley PH 《Biomaterials》2004,25(17):3853-3860
The implantation of ventriculo-peritoneal (VP) shunting systems is the most commonly performed neurological procedure in children with hydrocephalus. Although the overall complication risk is low, the cumulative risk of shunt failure is high and unfortunately results in a high prevalence of revision surgeries. In this study, we explored the concept that some pediatric patients may develop an immune response to either the proteins attached to the silicone implant surface or to the biomaterial itself, and that this reaction may contribute to VP shunt failure in some individuals. The data displays that the sterile shunt malfunction group had a higher rate of protein deposition and increased levels of autoantibodies to the extracted surface proteins as compared to individuals with functioning shunting systems. The precise nature of the shunt-bound proteins that serve as antigens in this experiment have not yet been determined. The data also indicated that some individuals develop antibodies to polymeric substances that cross-react with partially polymerized acrylamide. The detection of significant amounts of shunt-bound protein, antibody responses to these proteins and to polymeric substances suggest that an immunological response to these proteins may play a role in the mechanism behind sterile shunt malfunctions. 相似文献
65.
The corpus callosum (CC) is the main white matter tract in the brain and is involved in interhemispheric communication. Using
the whole-cell voltage-clamp technique, a study was made of K+-currents in primary cultured astrocytes from the CC of newborn rats. These cells were positive to glial fibrillary acidic
protein after culturing in Dulbecco’s Modified Eagle Medium (> 95% of cells) or in serum-free neurobasal medium with G5 supplement
(> 99% of cells). Astrocytes cultured in either medium displayed similar voltage-activated ion currents. In 81% of astrocytes,
the current had a transient component and a sustained component, which were blocked by 4-aminopyridine and tetraethylammonium,
respectively; and both had a reversal potential of −66 mV, indicating that they were carried by K+ ions. Based on the Ba2+-sensitivity and activation kinetics of the K+-current, two groups of astrocytes were discerned. One group (55% of cells) displayed a strong Ba2+ blockade of the K+-current whose activation kinetics, time course of decay, and the current-voltage relationship were modified by Ba2+. This current was greatly blocked (52%) by Ba2+ in a voltage-dependent way. Another group (45% of cells) presented weak Ba2+-blockade, which was only blocked 24% by Ba2+. The activation kinetics and time course of decay of this current component were unaffected by Ba2+. These results may help to understand better the roles of voltage-activated K+-currents in astrocytes from the rat CC in particular and glial cells in general. 相似文献
66.
Lethal encephalitis in myeloid differentiation factor 88-deficient mice infected with herpes simplex virus 1
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mansur DS Kroon EG Nogueira ML Arantes RM Rodrigues SC Akira S Gazzinelli RT Campos MA 《The American journal of pathology》2005,166(5):1419-1426
Herpes simplex virus 1 (HSV-1), a large DNA virus from the Herpesviridae family, is the major cause of sporadic lethal encephalitis and blindness in humans. Recent studies have shown the importance of Toll-like receptors (TLRs) in the immune response to HSV-1 infection. Myeloid differentiation factor 88 (MyD88) is a critical adaptor protein that is downstream to mediated TLR activation and is essential for the production of inflammatory cytokines. Here, we studied the relationship between MyD88 and HSV-1 using a purified HSV-1 isolated from a natural oral recurrent human infection. We observed the activation of TLR-2 by HSV-1 in vitro using Chinese hamster ovary cells stably transfected with a reporter gene. Interestingly, we found that only peritoneal macrophages from MyD88-/- mice, but not macrophages from TRL2-/- or from wild-type mice, were unable to produce tumor necrosis factor-alpha in response to HSV-1 exposure. Additionally, although TLR2-/- mice showed no enhanced susceptibility to intranasal infection with HSV-1, MyD88-/- mice were highly susceptible to infection and displayed viral migration to the brain, severe neuropathological signs of encephalitis, and 100% mortality by day 10 after infection. Together, our results suggest that innate resistance to HSV-1 is mediated by MyD88 and may rely on activation of multiple TLRs. 相似文献
67.
Immunoglobulin M (IgM)-glycoinositolphospholipid enzyme-linked immunosorbent assay: an immunoenzymatic assay for discrimination between patients with acute toxoplasmosis and those with persistent parasite-specific IgM antibodies 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Giraldo M Portela RW Snege M Leser PG Camargo ME Mineo JR Gazzinelli RT 《Journal of clinical microbiology》2002,40(4):1400-1405
In the present study we developed an enzyme-linked immunosorbent assay (ELISA) to measure immunoglobulin M (IgM) specific for glycoinositolphospholipids (GIPL) derived from tachyzoite membrane (IgM-GIPL ELISA). The sensitivity and specificity of the assay were compared with those of commercially available Toxoplasma-specific IgM serological tests, namely, immunofluorescence assay (IFA) with fixed tachyzoites and capture ELISA employing tachyzoite extracts. Our results show that all patients with acute toxoplasmosis, as determined by clinical data and conventional serological tests, were also positive by the IgM-GIPL ELISA. Interestingly, many patients that were classified as indeterminate, who had IgG with high avidity but positive results in the IgM-specific IFA and capture ELISA, were negative by the IgM-GIPL ELISA. Finally, we tested the sera from patients with rheumatoid arthritis and various parasitic infections and found no evidence of false positives in the IgM-GIPL ELISA. 相似文献
68.
Sputum Cytokine Levels in Patients with Pulmonary Tuberculosis as Early Markers of Mycobacterial Clearance
下载免费PDF全文
![点击此处可从《Clinical and Vaccine Immunology : CVI》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rodrigo Ribeiro-Rodrigues Tatiana Resende Co John L. Johnson Fabiola Ribeiro Moises Palaci Ricardo T. S Ethel L. Maciel Fausto E. Pereira Lima Valderio Dettoni Zahra Toossi W. Henry Boom Reynaldo Dietze Jerrold J. Ellner Christina S. Hirsch 《Clinical and Vaccine Immunology : CVI》2002,9(4):818-823
Sputum and serum from patients with active pulmonary tuberculosis (TB), healthy purified protein derivative-positive adults, and patients with bacterial pneumonia were collected to simultaneously assess local immunity in the lungs and peripheral blood. To determine whether cytokine profiles in sputum from TB patients and control subjects were a reflection of its cellular composition, cytospin slides were prepared in parallel and assessed for the presence of relative proportions of epithelial cells, neutrophils, macrophages, and T cells. Gamma interferon (IFN-γ) in sputum from TB patients was markedly elevated over levels for both control groups. With anti-TB therapy, IFN-γ levels in sputum from TB patients decreased rapidly and by week 4 of treatment were comparable to those in sputum from controls. Further, IFN-γ levels in sputum closely followed mycobacterial clearance. Although detected at fourfold-lower levels, IFN-γ immunoreactivities in serum followed kinetics in sputum. TNF-α, interleukin 8 (IL-8) and IL-6 also were readily detected in sputum from TB patients at baseline and responded to anti-TB therapy. In contrast to IFN-γ, however, TNF-α and IL-8 levels also were elevated in sputum from pneumonia controls. These data indicate that sputum cytokines correlate with disease activity during active TB of the lung and may serve as potential early markers for sputum conversion and response to anti-TB therapy. 相似文献
69.
Pituitary Adenylate-Cyclase-Activating Polypeptide (PACAP) Binding Sites and PACAP/Vasoactive Intestinal Polypeptide Receptor Expression in Human Pituitary Adenomas
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
70.
Long Jin Jiangyue Song William F. Chandler Barry G. England James B. Smart Ariel Barkan Ricardo V. Lloyd 《Endocrine pathology》1990,1(1):25-36
The effects of the hypothalamic hormones, thyrotropin-releasing hormone (TRH), and somatostatin (SRIH), and of phorbol 12-myristate
13-acetate (PMA) on PRL and GH secretion and messenger RNA (mRNA) levels were analyzed in 10 GH and/or PRL producing adenomas
after culturing the tumor cells in the presence of these secretagogues for 7 days. The expression of chromogranin A and B
mRNAs was also examined. All four of the clinically diagnosed GH adenomas expressed or secreted both GH and PRL while four
of six clinically diagnosed prolactinomas produced or secreted both PRL and GH. Prolactinomas had less than 10% of tumor cells
expressing chromogranin A mRNA while more than 40% of the adenoma cells expressed chromogranin B mRNA. TRH stimulated PRL
secretion and increased PRL mRNA levels while SRIH decreased GH secretion and mRNA expression in some cases. Unexpectedly,
PMA stimulated PRL mRNA levels four- to sevenfold above control levels in two adenomas and generally stimulated chromogranin
A and B mRNA expression but not GH mRNA, as determined by Northern hybridization and in situ hybridization analyses.
These results indicate that cultured prolactinoma cells express significantly more chromogranin B mRNA than chromogranin A
mRNA, and that PMA increases PRL mRNA expression in some prolactinomas, although the effect of PMA on various adenomas reflects
the heterogeneity of these tumors with respect to protein kinase C stimulation. 相似文献