全文获取类型
收费全文 | 3322篇 |
免费 | 195篇 |
国内免费 | 79篇 |
专业分类
耳鼻咽喉 | 116篇 |
儿科学 | 76篇 |
妇产科学 | 47篇 |
基础医学 | 465篇 |
口腔科学 | 20篇 |
临床医学 | 337篇 |
内科学 | 675篇 |
皮肤病学 | 18篇 |
神经病学 | 511篇 |
特种医学 | 164篇 |
外国民族医学 | 1篇 |
外科学 | 206篇 |
综合类 | 267篇 |
现状与发展 | 1篇 |
预防医学 | 163篇 |
眼科学 | 107篇 |
药学 | 267篇 |
2篇 | |
中国医学 | 94篇 |
肿瘤学 | 59篇 |
出版年
2023年 | 60篇 |
2022年 | 103篇 |
2021年 | 159篇 |
2020年 | 125篇 |
2019年 | 137篇 |
2018年 | 126篇 |
2017年 | 90篇 |
2016年 | 110篇 |
2015年 | 91篇 |
2014年 | 201篇 |
2013年 | 250篇 |
2012年 | 127篇 |
2011年 | 158篇 |
2010年 | 131篇 |
2009年 | 124篇 |
2008年 | 125篇 |
2007年 | 155篇 |
2006年 | 104篇 |
2005年 | 118篇 |
2004年 | 93篇 |
2003年 | 80篇 |
2002年 | 73篇 |
2001年 | 75篇 |
2000年 | 61篇 |
1999年 | 52篇 |
1998年 | 58篇 |
1997年 | 55篇 |
1996年 | 57篇 |
1995年 | 37篇 |
1994年 | 33篇 |
1993年 | 34篇 |
1992年 | 37篇 |
1991年 | 26篇 |
1990年 | 31篇 |
1989年 | 28篇 |
1988年 | 32篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 38篇 |
1984年 | 32篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有3596条查询结果,搜索用时 31 毫秒
21.
T. T. Khater K. J. Quinn J. Pena J. F. Baker B. W. Peterson 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1993,94(1):16-32
Latencies of normal and adapted feline vestibulo-ocular reflex (VOR) were studied in five cats by applying ± 20°/s horizontal head velocity steps (4000°/s2 acceleration) and measuring the elicited horizontal or vertical reflex eye responses. Normal VOR latency was 13.0 ms ± 1.9 SD. Short-term adaptation was then accomplished by using 2 h of paired horizontal sinusoidal vestibular stimulation and phase-synchronized vertical optokinetic stimulation (cross-axis adaptation). For long-term adaptation, cats wore ×0.25 or ×2.2 magnifying lenses for 4 days. The cats were passively rotated for 2 h/day and allowed to walk freely in the laboratory or their cages for the remainder of the time. The latency of the early (primary) adaptive response was 15.2ms±5.2 SD for crossaxis adaptation and 12.5 ms±3.9 SD for lens adaptation. This short-latency response appeared within 30 min after beginning the adaptation procedure and diminished in magnitude overnight. A late (secondary) adaptive response with latency of 76.8 ms±7.0 SD for cross-axis adaptation and 68.1 ms±8.8 SD for lens adaptation appeared after approximately 2 h of adaptation. It had a more gradual increase in magnitude than the primary response and did not diminish in magnitude overnight. These data suggest that brainstem VOR pathways are a site of learning for adaptive VOR modification, since the primary latency is short and has a similar latency to that of the normal VOR. 相似文献
22.
Farah Isse Mumin Benjamin Obukowho Emikpe Michael Ayodele Odeniyi 《Journal of immunoassay & immunochemistry》2020,41(3):311-321
ABSTRACTA study was conducted to evaluate mucoadhesive property and immunomodulatory effect of phytogenic gums from Boswellia frereana, Boswellia carteri andCommiphora myrrha on intranasal Peste des petits ruminants (PPR) vaccination in goats and sheep in an ex-vivo and in-vivo situations. Plant gums were purified, dried and compressed into 500gm tablets. Modified shear stress measurement technique was used on freshly excised trachea and intestine tissues of goat to measure peak adhesion time. Forty eight animals (24 goats and 24 sheep) were divided into eight groups (of 3 goats and 3 sheep) and immunized intranasally with gum-vaccine combinations in two ratios (1:1, 1:2). Antibody against PPR virus was measured on day 14, 28, 42 and 56 post vaccination using H-based PPR bELISA. The peak adhesion time of the different gums was transient. PPR virus antibodies were detected in all immunized goats and sheep but not in unvaccinated control. The best percentage inhibition was recorded for Boswellia carteri-vaccine combination group at a ratio of 1:1. Administration of Boswellia carteri-PPR vaccine combination through intranasal or subcutaneous route, elicited similar antibody titre, implying that the intranasal route may be used as a non-invasive alternative delivery in PPR vaccination of small ruminants. 相似文献
23.
Reservoirs of latent HIV-1 in T cells and macrophages pose one of the major obstacles that hamper final eradication of HIV-1 from infected patients. Targeting costimulatory molecules expressed on cell types harboring latent HIV-1 to achieve reactivation may provide a new approach to overcome this problem. One such molecule is CD40, a member of the tumor necrosis factor (TNF)-receptor family. Using THP89GFP cells as a model for latently infected macrophages, we demonstrate that trimeric forms of recombinant CD154 allow for the direct reactivation of latent HIV-1 infection. Reactivation is augmented by the release of TNF-alpha. The presence of TNF-alpha is also crucial for the expression of late structural genes such as p24 Gag. In addition, levels of secreted TNF-alpha are sufficiently high to reactivate latent HIV-1 in a latently HIV-1-infected T-cell line (J89GFP). Taken together, our results demonstrate that costimulatory molecules may be attractive targets to reactivate latent HIV-1 in infected patients. 相似文献
24.
Summary: Chemical shift trends in the methylene and α substituent regions of 13C NMR spectra of vinyl polymers have been analyzed in terms of a three‐state rotational isomeric states (RIS) model and the γ‐gauche effect. In this framework, it has been demonstrated that the three sequencing rules observed for poly(propylene) can also be expected to work for many other vinyl polymers. The first two rules, justified in terms of the conformational perturbability of stereosequences, turn out to be respected by a considerable number of NMR spectra. On the other hand, the same spectral data are in substantial disagreement with the third rule. An explanation is proposed for this breakdown.
25.
Matsuyama A Yonemitsu N Hayashida S Watanabe K Sugihara H Inokuchi A 《Pathology international》2003,53(1):46-50
Osteosarcoma is one of the neoplasms that may occur following exposure to radiation. A case of osteosarcoma arising in the craniofacial bone with a short latency period of 3 years after radiotherapy for maxillary squamous cell carcinoma is described. A 64-year-old-man underwent right partial maxillectomy and chemoradiotherapy due to squamous cell carcinoma of his right maxillary sinus. Histologically, the tumor was composed of moderately differentiated squamous cell carcinoma with a component of spindle cell carcinoma. Three years later, osteosarcoma developed in the craniofacial bone within the irradiation field of the first tumor. Detailed histological examination demonstrated that there was no component of osteosarcoma in the first tumor or squamous cell carcinoma in the second tumor. Radiation-induced osteosarcoma usually occurs after a long latency period of more than 10 years after the radiotherapy. In this case, osteosarcoma was possibly a radiation-induced osteosarcoma with a short latency period of 3 years. 相似文献
26.
Alyce C. Russell Agnieszka Kepka Irena Trbojević-Akmačić Ivo Ugrina Manshu Song Jennie Hui Michael Hunter Simon M. Laws Gordan Lauc Wei Wang 《Immunobiology》2019,224(1):110-115
Background
Increased body fat may be associated with an increased risk of developing an underlying pro-inflammatory state, thus leading to greater risk of developing certain chronic conditions. Immunoglobulin G has the ability to exert both anti- and pro-inflammatory effects, and the N-glycosylation of the fragment crystallisable portion is involved in mediating this process. Body mass index, a rudimentary yet gold standard indication for body fat, has been shown to be associated with agalactosylated immunoglobulin G N-glycans.Aim
We aimed to determine the association between increased body fat and the immunoglobulin G glycosylation features, comparing body mass index to other measures of body fat distribution.Methods
We investigated a sample of 637 community-based 45–69?year olds, with mixed phenotypes, residing in Busselton, Western Australia. Body mass index and the waist-to-hip and waist-to-height ratios were calculated using anthropometry, while dual-energy x-ray absorptiometry was performed to gain an accurate measure of total and area specific body fat. Serum immunoglobulin GN-glycans were analysed by ultra-performance liquid chromatography.Results
Twenty-two N-glycan peaks were found to be associated with at least one of the fat measures. While the previous association of body mass index to agalactosylated immunoglobulin G was replicated, measures of central adiposity explained the most variation in the immunoglobulin G glycome.Conclusion
Central adiposity is associated with an increased pro-inflammatory fraction of immunoglobulin G, suggesting that the android/gynoid ratio or waist-to-height ratio instead be considered when controlling for adiposity in immunoglobulin G glycome biomarker studies. 相似文献27.
Leslie C. Grammer Loui Silvestri Irena M. Suszko Martha A. Shaughnessy Roy Patterson 《The Journal of allergy and clinical immunology》1983,72(2):160-167
The standardization procedures for polymerized ragweed (PRW) must evaluate activity of PRW with assessments that differ from those used for standard unmodified extracts. This is because PRW allergens are different from conventional ragweed extracts in that they are much greater in average molecular weight and much lower in allergenicity for equivalent immunogenicity. We have evaluated seven samples of PRW for three parameters: allergenicity as determined by cutaneous end point titration, molecular weight distribution as determined by Sephadex G-200 chromatography, and availability of antigen E (AgE) determinants as measured by the ability of an extract to inhibit AgE binding to antibody by using a modification of the Farr technique. The skin test titers and molecular weight profiles provide information as to the safety of a PRW preparation and antigen-binding inhibitory activity gives information about allergenicity and immunogenicity. Appropriate limits may be set for each of these parameters to standardize PRW for clinical use. 相似文献
28.
Jiang R Kanamori M Satoh Y Fukuda M Ikuta K Murakami M Sairenji T 《Journal of medical virology》2003,70(2):244-252
Eliminating Epstein-Barr virus (EBV) genomes from infected cells is an intriguing theoretical strategy in therapy for EBV-associated malignant diseases. Respective patterns were characterized for hydroxyurea (HU)-promoted loss of EBV genomes from EBV-infected epithelioid cell lines derived from the noncancerous portion of gastric carcinoma tissues and Burkitt's lymphoma (BL) cell lines. Epithelioid cell lines GT38 and PN were less sensitivity to HU than BL cell lines Akata, Raji, and Daudi in terms of cell growth inhibition and cell cycle arrest. On passage in medium with 50 microM HU, the fraction of EBV nuclear antigen (EBNA)-positive cells was reduced substantially in the BL cell lines, but only slightly in the epithelioid cell lines. EBV DNA was reduced in Akata, Raji, and Daudi cells upon passage in 50 microM HU by 95%, 70%, and 50%, respectively, but by only 10% in GT38 cells, in which EBV DNA reduction was enhanced at increased concentrations of HU. This indicates that EBV genome is more easily lost from BL cell lines than from epithelioid cell lines upon culturing in HU. These findings support the view that the elimination of EBV could be therapeutically effective in EBV-associated BL by HU. 相似文献
29.
M. Jalkanen H. Larjava J. Heino T. Vihersaari J. Peltonen R. Penttinen 《Immunology letters》1982,4(5):259-261
In the present work we demonstrate that non-activated, cultured rat peritoneal macrophages deplete arginine from their culture medium and that the use of this medium in fibroblast cultures may lead to decreased synthesis of collagen by fibroblasts. 相似文献
30.
Auditory Discrimination and the Eyeblink 总被引:1,自引:0,他引:1
Lance O. Bauer Barbara D. Strock Robert Goldstein John A. Stern Larry C. Walrath 《Psychophysiology》1985,22(6):636-641
This experiment evaluated the association between blinking and cognitive activities. Subjects received 200 and 400 ms tones (1 KHz) at fixed intervals in a duration discrimination paradigm. One group (“Task”) was instructed to respond to the stimuli on the basis of duration and another (“No-Task”) was instructed to ignore the stimuli. Blink activity (latency, rate, duration) and performance (RT, hit and false alarm rates) measures were evaluated. A first analysis (Task subjects only) indicated that stimulus duration had significant effects on RT and blink latency; both were generally longer following the 400-ms than the 200-ms stimuli. In a second analysis, involving Task and No-Task subjects, blink latencies were shorter in the Task group. Blink and eyelid closure durations increased over the task period in both analyses. These effects suggest that blinks occur when attentional processes wane. 相似文献