全文获取类型
收费全文 | 2651篇 |
免费 | 194篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 95篇 |
妇产科学 | 29篇 |
基础医学 | 465篇 |
口腔科学 | 21篇 |
临床医学 | 347篇 |
内科学 | 460篇 |
皮肤病学 | 72篇 |
神经病学 | 484篇 |
特种医学 | 65篇 |
外科学 | 240篇 |
综合类 | 14篇 |
预防医学 | 246篇 |
眼科学 | 19篇 |
药学 | 117篇 |
中国医学 | 4篇 |
肿瘤学 | 154篇 |
出版年
2023年 | 24篇 |
2022年 | 38篇 |
2021年 | 47篇 |
2020年 | 53篇 |
2019年 | 70篇 |
2018年 | 58篇 |
2017年 | 52篇 |
2016年 | 72篇 |
2015年 | 88篇 |
2014年 | 89篇 |
2013年 | 116篇 |
2012年 | 172篇 |
2011年 | 198篇 |
2010年 | 119篇 |
2009年 | 85篇 |
2008年 | 157篇 |
2007年 | 198篇 |
2006年 | 148篇 |
2005年 | 167篇 |
2004年 | 125篇 |
2003年 | 97篇 |
2002年 | 127篇 |
2001年 | 28篇 |
2000年 | 34篇 |
1999年 | 34篇 |
1998年 | 18篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 24篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1977年 | 13篇 |
1974年 | 9篇 |
1973年 | 12篇 |
1972年 | 21篇 |
1971年 | 8篇 |
排序方式: 共有2852条查询结果,搜索用时 9 毫秒
31.
Liddell AM Stockham SL Scott MA Sumner JW Paddock CD Gaudreault-Keener M Arens MQ Storch GA 《Journal of clinical microbiology》2003,41(10):4617-4622
To investigate the species distribution of Ehrlichia present in Missouri dogs, we tested 78 dogs suspected of having acute ehrlichiosis and 10 healthy dogs. Blood from each dog was screened with a broad-range 16S rRNA gene PCR assay that detects known pathogenic species of Ehrlichia and ANAPLASMA: The species was determined by using species-specific PCR assays and nucleotide sequencing. Ehrlichia antibody testing was performed by using an indirect immunofluorescence assay with Ehrlichia chaffeensis as the antigenic substrate. The broad-range assay detected Ehrlichia or Anaplasma DNA in 20 (26%) of the symptomatic dogs and 2 (20%) of the asymptomatic dogs. E. ewingii accounted for 20 (91%), and E. chaffeensis accounted for 1 (5%) of the positives. Anaplasma phagocytophilum DNA was detected in one dog, and the sequences of regions of the 16S rRNA gene and the groESL operon amplified from the blood of this dog matched the published sequences of this organism. Antibodies reactive with E. chaffeensis were detected in 14 (67%) of the 21 PCR-positive dogs and in 12 (19%) of the 64 PCR-negative dogs. Combining the results of PCR and serology indicated that 33 (39%) of 85 evaluable dogs had evidence of past or current Ehrlichia infection. We conclude that E. ewingii is the predominant etiologic agent of canine ehrlichiosis in the areas of Missouri included in this survey. E. canis, a widely recognized agent of canine ehrlichiosis, was not detected in any animal. The finding of E. ewingii in asymptomatic dogs suggests that dogs could be a reservoir for this Ehrlichia species. 相似文献
32.
Raoud Marayati Laura V. Bownes Colin H. Quinn Nikita Wadhwani Adele P. Williams Hooper R. Markert Venkatram Atigadda Jamie M. Aye Jerry E. Stewart Karina J. Yoon Elizabeth A. Beierle 《Journal of pediatric surgery》2021,56(6):1165-1173
IntroductionThe poor therapeutic efficacy seen with current treatments for neuroblastoma may be attributed to stem cell-like cancer cells (SCLCCs), a subpopulation of cancer cells associated with poor prognosis and disease recurrence. Retinoic acid (RA) is a differentiating agent used as maintenance therapy for high-risk neuroblastoma but nearly half of children treated with RA relapse. We hypothesized that 6-Methyl-UAB30 (6-Me), a second-generation rexinoid recently developed with a favorable toxicity profile compared to RA, would reduce cancer cell stemness in human neuroblastoma patient-derived xenografts (PDXs).MethodsCells from three neuroblastoma PDXs were treated with 6-Me and proliferation, viability, motility, and cell-cycle progression were assessed. CD133 expression, sphere formation, and mRNA abundance of stemness and differentiation markers were evaluated using flow cytometry, in vitro extreme limiting dilution analysis, and real-time PCR, respectively.ResultsTreatment with 6-Me decreased proliferation, viability, and motility, and induced cell-cycle arrest and differentiation in all three neuroblastoma PDXs. In addition, 6-Me treatment led to decreased CD133 expression, decreased sphere-forming ability, and decreased mRNA abundance of Oct4, Nanog, and Sox2, indicating decreased cancer cell stemness.Conclusions6-Me decreased oncogenicity and reduced cancer cell stemness of neuroblastoma PDXs, warranting further exploration of 6-Me as potential novel therapy for neuroblastoma. 相似文献
33.
34.
Pilot study of a visitor volunteer programme for community elderly people receiving home health care
MacIntyre I Corradetti P Roberts J Browne G Watt S Lane A 《Health & social care in the community》1999,7(3):225-232
There is a need to evaluate community support programmes for elderly people. In this randomized control trial (RCT), we determined the effectiveness of 'friendly visitors' in a volunteer programme of a visiting nurses organization in Southern Ontario, Canada. The Volunteer Friendly Visitor Programme was developed to support elderly people receiving homemaking and nursing care in the community. Volunteers are screened, trained, interviewed and matched to homebound elderly clients for general interest, visit expectations and personality. Volunteers spend three to four hours on average per week with clients socializing in mutually agreed-upon ways. The nursing staff identified clients who were lonely for this additional support. These newly-referred clients were randomly allocated to receive a friendly visitor or not for six weeks. Those receiving the volunteer visitor improved in life satisfaction and two social support measures: worth and social integration. Thus, the addition of volunteer visitors to planned homemaking and nursing care made a difference for elderly in the community. 相似文献
35.
Clinical experience and previous research show that older people at risk of falling can become anxious at the thought of being on the floor, therefore physiotherapists and occupational therapists may be reluctant to teach them how to get up.Old people's reactions to two different methods of teaching them this skill are compared (three groups, mean age 84 years). The conventional method requires people to be helped down to the floor and then to learn how to get on to their knees prior to getting up with the help of furniture. An alternative method, based on backward-chaining principles, does not require that people start from the floor and reduces the likelihood of them experiencing failure. The activity is broken down into small steps — the last step in the chain being taught first.It is concluded that:
- 1 The backward-chaining method of teaching elderly people how to get up from the floor is much less stressful to older people and to staff than the conventional method.
- 2 Older people are slightly more likely to learn successfully how to get up from the floor by the backward-chaining method which, even if they are not successful, provides them with functionally relevant exercise.
- 3 Older people who cannot learn to get up from the floor should be helped to develop alternative strategies for summoning help and for preventing the consequences of the long lie.
Key Words: Elderly people; falls; long lie 相似文献
36.
Storch DD 《The Psychiatric hospital》1991,22(1):5-9
Violence perpetrated on the staff in our psychiatric hospitals is increasing. We believe an in-hospital support group for employee victims of violence is an effective and economical means of helping our staff, our patients, and the hospital in general. We believe that it is crucial to provide education about and to foster sensitization to issues of violence and that our staff must work together within the facility and with outside agencies, such as those in the legal system. We are just starting our support group at the Carter Center, and this paper discusses various practical points encountered thus far and some of the theoretical issues surrounding our beginning. We believe ours is an important prototype of staff support groups, which are vitally needed. I hope to publish a follow-up report on our group and the progress it has made. 相似文献
37.
The endogenous neurotoxin 1-methyl-6,7-dihydroxy-1,2,3, 4-tetrahydroisoquinoline (salsolinol), which is structurally similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), has been reported to inhibit mitochondrial complex I (NADH-Q reductase) activity as does the MPTP metabolite 1-methyl-4-phenylpyridinium ion (MPP(+)). However, the mechanism of salsolinol leading to neuronal cell death is still unknown. Thus, we correlated indices of cellular energy production and cell viability in human dopaminergic neuroblastoma SH-SY5Y cells after exposure to salsolinol and compared these results with data obtained with MPP(+). Both toxins induce time and dose-dependent decrease in cell survival with IC(50) values of 34 microM and 94 microM after 72 h for salsolinol and MPP(+), respectively. Furthermore, salsolinol and MPP(+) produce a decrease of intracellular net ATP content with IC(50) values of 62 microM and 66 microM after 48 h, respectively. In contrast to MPP(+), salsolinol does not induce an increase of intracellular net NADH content. In addition, enhancing glycolysis by adding D-glucose to the culture medium protects the cells against MPP(+) but not salsolinol induced cellular ATP depletion and cytotoxicity. These results suggest that cell death induced by salsolinol is due to impairment of cellular energy supply, caused in particular by inhibition of mitochondrial complex II (succinate-Q reductase), but not complex I. 相似文献
38.
Elieser Gorelik Douglas P Landsittel Adele M Marrangoni Francesmary Modugno Lyudmila Velikokhatnaya Matthew T Winans William L Bigbee Ronald B Herberman Anna E Lokshin 《Cancer epidemiology, biomarkers & prevention》2005,14(4):981-987
Early detection of ovarian cancer might improve clinical outcome. Some studies have shown the role of cytokines as a new group of tumor markers for ovarian cancer. We hypothesized that a panel comprised of multiple cytokines, which individually may not show strong correlation with the disease, might provide higher diagnostic power. To evaluate the diagnostic utility of cytokine panel, we used a novel multianalyte LabMAP profiling technology that allows simultaneous measurement of multiple markers. Concentrations of 24 cytokines (cytokines/chemokines, growth, and angiogenic factors) in combination with cancer antigen-125 (CA-125), were measured in sera of 44 patients with early-stage ovarian cancer, 45 healthy women, and 37 patients with benign pelvic tumors. Six markers, i.e., interleukin (IL)-6, IL-8, epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), monocyte chemoattractant protein-1 (MCP-1), and CA-125, showed significant differences in serum concentrations between ovarian cancer and control groups. Out of this group, IL-6, IL-8, VEGF, EGF, and CA-125, were used in a classification tree analysis that resulted in 84% sensitivity at 95% specificity. The receiver operator characteristic curve created using the combination of markers produced sensitivities between 90% and 100% in the area of 80% to 90% specificity, whereas the receiver operator characteristic curve for CA-125 alone resulted in sensitivities of 70% to 80%. The classification tree analysis for discrimination of benign condition from ovarian cancer used CA-125, granulocyte colony-stimulating factor (G-CSF), IL-6, EGF, and VEGF resulting in 86.5% sensitivity and 93.0% specificity. The presented data show that simultaneous testing of a panel of serum cytokines and CA-125 using LabMAP technology may present a promising approach for ovarian cancer detection. 相似文献
39.
Antioxidant properties of ursodeoxycholic acid 总被引:5,自引:0,他引:5
Lapenna D Ciofani G Festi D Neri M Pierdomenico SD Giamberardino MA Cuccurullo F 《Biochemical pharmacology》2002,64(11):1661-1667
We have investigated potential antioxidant properties of the clinically relevant bile acid UDCA, which reaches therapeutic concentrations up to 0.09 and 29 mM, respectively, in human plasma and bile. UDCA was an excellent scavenger of OHz.rad; generated by FeCl(3)-EDTA, H(2)O(2) and ascorbate in the deoxyribose oxidation test, showing IC(min) and IC(50) values of 0.02 and 0.2 mM, respectively, and a second-order rate constant for reaction with OHz.rad; of 2+/-0.1 x 10(10)M(-1)s(-1). Notably, the drug could enhance at 1.5 mM concentration the antioxidant capacity of human bile against OHz.rad;-induced deoxyribose oxidation. UDCA also showed antioxidant effects in the deoxyribose test performed with nonchelated iron ions, such as Fe(2+) plus H(2)O(2) (IC(min): 7 mM, IC(50): 20 mM) or Fe(3+) plus H(2)O(2) and ascorbate (IC(min): 0.3 mM, IC(50): 5 mM), and inhibited ferrozine-Fe(2+) and desferrioxamine-Fe(3+) complexes formation with IC(50) values of, respectively, 12 and 0.3 mM, indicating that the drug interacts more with iron(III) than with iron(II). Moreover, UDCA significantly inhibited phospholipid liposome peroxidation induced by the OHz.rad;-generating system FeCl(3)-EDTA, H(2)O(2) and ascorbate (IC(min): 0.75 mM, IC(50): 3 mM), and by peroxyl radicals generated in the aqueous phase by AAPH (IC(min): 8 mM, IC(50): 14 mM). UDCA, even at 25 mM concentration, was ineffective on the lipoperoxidation mediated by Fe(2+) alone, but at the same concentration counteracted significantly that by Fe(3+) plus ascorbate, further pointing to its preferential antioxidant interaction with iron(III).In conclusion, UDCA has direct antioxidant properties, which are especially relevant against Fe(3+)- and OHz.rad;-dependent biomolecular oxidative damage; such properties are evident at therapeutically relevant drug concentrations, suggesting that UDCA could act as an antioxidant in vivo. 相似文献
40.