全文获取类型
收费全文 | 10572篇 |
免费 | 575篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 103篇 |
儿科学 | 280篇 |
妇产科学 | 139篇 |
基础医学 | 1561篇 |
口腔科学 | 269篇 |
临床医学 | 990篇 |
内科学 | 2111篇 |
皮肤病学 | 249篇 |
神经病学 | 1143篇 |
特种医学 | 564篇 |
外科学 | 1524篇 |
综合类 | 44篇 |
一般理论 | 2篇 |
预防医学 | 568篇 |
眼科学 | 151篇 |
药学 | 713篇 |
中国医学 | 18篇 |
肿瘤学 | 768篇 |
出版年
2023年 | 45篇 |
2022年 | 97篇 |
2021年 | 193篇 |
2020年 | 126篇 |
2019年 | 174篇 |
2018年 | 234篇 |
2017年 | 158篇 |
2016年 | 248篇 |
2015年 | 292篇 |
2014年 | 383篇 |
2013年 | 438篇 |
2012年 | 692篇 |
2011年 | 686篇 |
2010年 | 436篇 |
2009年 | 449篇 |
2008年 | 640篇 |
2007年 | 674篇 |
2006年 | 723篇 |
2005年 | 712篇 |
2004年 | 669篇 |
2003年 | 640篇 |
2002年 | 566篇 |
2001年 | 148篇 |
2000年 | 120篇 |
1999年 | 108篇 |
1998年 | 156篇 |
1997年 | 92篇 |
1996年 | 77篇 |
1995年 | 75篇 |
1994年 | 77篇 |
1993年 | 53篇 |
1992年 | 59篇 |
1991年 | 49篇 |
1990年 | 41篇 |
1989年 | 44篇 |
1988年 | 41篇 |
1987年 | 46篇 |
1986年 | 28篇 |
1985年 | 36篇 |
1984年 | 42篇 |
1983年 | 40篇 |
1982年 | 30篇 |
1981年 | 17篇 |
1980年 | 29篇 |
1979年 | 23篇 |
1978年 | 32篇 |
1977年 | 18篇 |
1976年 | 24篇 |
1954年 | 24篇 |
1938年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Julian F Thayer Martica Hall John J Sollers Joachim E Fischer 《International journal of psychophysiology》2006,59(3):244-250
Alcoholism and heavy drinking are associated with a number of physiological, behavioral, affective, and cognitive problems. One such problem involves dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, with alcoholics showing higher basal cortisol levels and reduced inhibitory feedback control. In addition, alcohol consumption is associated with decreased heart rate variability (HRV). In the present study we examined the relationships among alcohol consumption, cortisol excretion, and HRV in 542 apparently healthy men. Men in the top tertile of self-reported alcohol consumption had higher cortisol levels and lower HRV compared to men in the lower two tertiles of alcohol consumption. In addition, the inverse relationship between cortisol and HRV was greatly attenuated in the heavy drinking group even after accounting for a number of potential confounding factors. These results support prior research on the HPA axis dysregulation in alcoholics and suggest impaired inhibitory control of the HPA axis in heavy drinkers. The findings are consistent with the neurovisceral integration model, which links central and peripheral processes, and may provide a comprehensive framework for the future investigation of the complex mix of physiological, behavioral, affective, and cognitive factors which comprise the heavy drinking phenotype. 相似文献
73.
74.
Joachim Böttcher M.D. Alexander Pfeil Anders Rosholm Ph.D. Max-Ludwig Schäfer Ansgar Malich M.D. Alexander Petrovitch M.D. Bettina Seidl Gabriele Lehmann M.D. Hans-Joachim Mentzel M.D. Gert Hein M.D. Gunter Wolf M.D. Werner A. Kaiser M.D. M.S. 《Journal of digital imaging》2006,19(3):279-288
Purpose Our study evaluates digital x-ray radiogrammetry (DXR) and Radiogrammetry Kit (RK) as a new diagnostic method for the measurement
of disease-related osteoporosis including quantification of joint space narrowing dependent on the severity of rheumatoid
arthritis (RA).
Materials and Methods A total of 172 unselected patients with RA underwent computerized measurements of bone mineral density (BMD) and metacarpal
index (MCI) by DXR, as well as a semiautomated measurement of joint space distances at the metacarpal–phalangeal articulation
(JSD-MCP 2–5), both were analyzed from plain radiographs of the nondominant hand.
Results Correlations between DXR-BMD and DXR-MCI vs. parameters of RK were all significant (0.34 < R < 0.61; p < 0.01). An expected negative association was observed between RK parameters and the different scoring methods (−0.27 < R < −0.59). The maximum relative decrease in BMD vs. MCI as measured by DXR between the highest and lowest RA severity group
was −27.7% vs. −27.5% (p < 0.01) for the modified Larsen Score, whereas the minimal value of relative DXR-BMD and DXR-MCI reduction could be documented
for the Sharp Erosion Score (−20.8% vs. −26.8%; p < 0.01). The relative reduction of mean JSD-MCP using RK significantly varied from −25.0% (Sharp Erosion Score) to −41.2%
(modified Larsen Score). In addition, an excellent reproducibility of DXR and RK could be verified.
Conclusion DXR in combination with RK could be a promising, widely available diagnostic tool to supplement the different scoring methods
of RA with quantitative data, allowing an earlier and improved diagnosis and more precision in determining disease progression. 相似文献
75.
Joachim Saloga Gideon Lack Kathrine Bradley Harald Renz Gary Larsen Donald Y. M. Leung Erwin W. Gelfand 《European journal of immunology》1994,24(12):3140-3147
We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive Vβ8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of Vβ8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization to OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the Vβ8 T cell population, they did reduce the proliferative response of Vβ8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive Vβ8 T cells. 相似文献
76.
Zacher T Knerr I Rascher W Kalden JR Wassmuth R 《Clinical immunology (Orlando, Fla.)》2002,105(1):17-24
Dendritic cells (DC) may play an important role in the immunopathogenesis of type 1 diabetes mellitus (DM-1). In this study, we have analyzed phenotypical changes during cytokine-driven maturation from CD14+ monocytes to mature DC and DC-dependent T-cell stimulation in recent-onset pediatric DM-1 patients and healthy controls. DC maturation was monitored by flow cytometric analyses for the expression of surface markers (HLA-DR, CD1a, CD40, CD80, CD86, CD83, CD14, CD32, mannose-receptor, and CD11c). Flow cytometric analysis of isolated peripheral blood monocytes did not reveal apparent differences between patients and controls. During DC maturation no obvious differences in the expression patterns of surface markers over time or evidence for maturation impairments in DM-1 patients could be appreciated. Solely, a marginal, but significant, transient down-regulation of CD1a on Day 3 (mean MDFI 3.82 vs 7.25; P = 0.021), which was accompanied by an increase of IL-6, could be observed. The comparison of mature DCs (Day 10) between patients and controls indicated no significant differences, except for CD83 (mean MDFI 1.7 vs 1.5; P = 0.042) and CD80 (mean MDFI 15.92 vs 12.73; P = 0.042). Moreover, no difference in T-cell stimulatory capacity was seen. In conclusion, our analysis of a cohort of recent-onset DM-1 patients and controls does not support a role for disease-related alterations in cytokine-driven maturation of monocyte-derived DC. 相似文献
77.
The hemocompatibility of biomaterials is highly dependent on the adhesion and activation of platelets. Surface-adsorbed fibrinogen has a dominant role in promoting platelet adhesion to artificial surfaces by binding glycoprotein IIb-IIIa (GPIIb-IIIa), the major platelet membrane receptor. Using quartz crystal microbalance with dissipation monitoring (QCM-D), we have investigated the material-dependent binding kinetics of purified GPIIb-IIIa to polymer-adsorbed fibrinogen. The following ranking of polymer-adsorbed mass (fibrinogen and GPIIb-IIIa) to test polymers could be established: poly[desaminotyrosyl-tyrosine ethyl (DTE) carbonate]/poly(lactide-co-glycolide)>poly[DTE co-5% poly(ethylene glycol) carbonate]. The QCM-D fibrinogen adsorption data were confirmed using an immunofluorescence assay. A synthetic RGD-containing peptide, but not a control peptide, inhibited GPIIb-IIIa binding to polymer-adsorbed fibrinogen, demonstrating the specificity of binding. Importantly, the binding efficiency of purified GPIIb-IIIa to polymer-adsorbed fibrinogen correlated with increased platelet adhesion in an in vitro model. Theoretical simulations using a Voight-based model provided quantitative data on the thickness and viscoelastic properties of the polymer-adsorbed protein layers. The precision of the modeling technique was limited with respect to the shear moduli values, leading to large variations. However, the other modeling parameters showed reproducible results. The thickness of both protein layers was polymer-dependent and ranged from 5 to 35 nm and the viscosity from 0.001 to 0.005 kg/ms, whereas the protein layer densities showed little differences between the test polymers. These results suggest that material-dependent changes in the thickness and viscoelastic properties of adsorbed fibrinogen-GPIIb-IIIa layers are crucial factors in the binding behavior of platelets to biomaterials. 相似文献
78.
Paul J Martin George B McDonald Jean E Sanders Claudio Anasetti Frederick R Appelbaum H Joachim Deeg Richard A Nash Effie W Petersdorf John A Hansen Rainer Storb 《Biology of blood and marrow transplantation》2004,10(5):320-327
The reported incidence of grades II to IV acute graft-versus-host disease (GVHD) after hematopoietic cell transplantation with HLA-identical sibling donors has increased considerably during the past 15 to 20 years at our center. The purpose of this study was to evaluate the potential reasons for this change. We reviewed organ stages and overall grades of GVHD for 2220 patients who received a first marrow or peripheral blood cell transplant from an HLA-identical sibling or an HLA-allele-matched unrelated donor with the use of a posttransplantation immunosuppressive regimen that included both methotrexate and cyclosporine between 1985 and 2001. The most striking change was an increased incidence of stage 1 gut involvement from 10% to 20% before 1992 to 50% to 60% since 1992, both with related and unrelated donors. This change increased the incidence of grade II GVHD with sibling donors, such that the overall incidence of grade II to IV GVHD is now 60% to 70%. Among patients with chronic myeloid leukemia in chronic phase, the increasingly frequent diagnosis of acute GVHD since 1992 has not been associated with decreased survival. A high diagnostic sensitivity and increased awareness that gut GVHD can occur without skin involvement account for the increased incidence of acute GVHD at our center. 相似文献
79.
80.
Bernhard W. Endres Joachim H. Wendorff Bernd Reck Helmut Ringsdorf 《Macromolecular chemistry and physics.》1987,188(6):1501-1509
The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the flexible spacer within the chain backbone and that the concentration of the side chains is comparatively small. Two low-temperature relaxation processes were observed to occur in the glassy smectic and the crystalline state. They are attributed to intramolecular motions with in the mesogenic groups. 相似文献