全文获取类型
收费全文 | 13711篇 |
免费 | 872篇 |
国内免费 | 346篇 |
专业分类
耳鼻咽喉 | 155篇 |
儿科学 | 981篇 |
妇产科学 | 298篇 |
基础医学 | 1794篇 |
口腔科学 | 448篇 |
临床医学 | 881篇 |
内科学 | 2060篇 |
皮肤病学 | 193篇 |
神经病学 | 765篇 |
特种医学 | 204篇 |
外国民族医学 | 1篇 |
外科学 | 2345篇 |
综合类 | 1249篇 |
预防医学 | 1511篇 |
眼科学 | 90篇 |
药学 | 1115篇 |
1篇 | |
中国医学 | 202篇 |
肿瘤学 | 636篇 |
出版年
2024年 | 21篇 |
2023年 | 196篇 |
2022年 | 332篇 |
2021年 | 389篇 |
2020年 | 362篇 |
2019年 | 389篇 |
2018年 | 369篇 |
2017年 | 399篇 |
2016年 | 415篇 |
2015年 | 494篇 |
2014年 | 792篇 |
2013年 | 975篇 |
2012年 | 697篇 |
2011年 | 809篇 |
2010年 | 619篇 |
2009年 | 634篇 |
2008年 | 654篇 |
2007年 | 680篇 |
2006年 | 605篇 |
2005年 | 525篇 |
2004年 | 453篇 |
2003年 | 388篇 |
2002年 | 346篇 |
2001年 | 294篇 |
2000年 | 303篇 |
1999年 | 236篇 |
1998年 | 250篇 |
1997年 | 225篇 |
1996年 | 182篇 |
1995年 | 200篇 |
1994年 | 177篇 |
1993年 | 160篇 |
1992年 | 118篇 |
1991年 | 153篇 |
1990年 | 123篇 |
1989年 | 107篇 |
1988年 | 105篇 |
1987年 | 97篇 |
1986年 | 105篇 |
1985年 | 97篇 |
1984年 | 83篇 |
1983年 | 37篇 |
1982年 | 48篇 |
1981年 | 52篇 |
1980年 | 39篇 |
1979年 | 36篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1976年 | 19篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
《Vaccine》2020,38(39):6141-6152
Influenza vaccination is considered the most valuable means to prevent and control seasonal influenza infections, which causes various clinical symptoms, ranging from mild cough and fever to even death. Among various influenza vaccine types, the inactivated subunit type is known to provide improved safety with reduced reactogenicity. However, there are some drawbacks associated with inactivated subunit type vaccines, with the main ones being its low immunogenicity and the induction of Th2-biased immune responses. In this study, we investigated the role of a single-stranded RNA (ssRNA) derived from the intergenic region in the internal ribosome entry site of the Cricket paralysis virus as an adjuvant rather than the universal vaccine for a seasonal inactivated subunit influenza vaccine. The ssRNA adjuvant stimulated not only well-balanced cellular (indicated by IgG2a, IFN-γ, IL-2, and TNF-α) and humoral (indicated by IgG1 and IL-4) immune responses but also a mucosal immune response (indicated by IgA), a key protector against respiratory virus infections. It also increases the HI titer, the surrogate marker of influenza vaccine efficacy. Furthermore, ssRNA adjuvant confers cross-protective immune responses against heterologous influenza virus infection while promoting enhanced viral clearance. Moreover, ssRNA adjuvant increases the number of memory CD4+ and CD8+ T cells, which can be expected to induce long-term immune responses. Therefore, this ssRNA-adjuvanted seasonal inactivated subunit influenza vaccine might be the best influenza vaccine generating robust humoral and cellular immune responses and conferring cross-protective and long-term immunity. 相似文献
12.
An important part of fundamental research in catalysis is based on theoretical and modeling foundations which are closely connected with studies of single-crystalline catalyst surfaces. These so-called model catalysts are often prepared in the form of epitaxial thin films, and characterized using advanced material characterization techniques. This concept provides the fundamental understanding and the knowledge base needed to tailor the design of new heterogeneous catalysts with improved catalytic properties. The present contribution is devoted to development of a model catalyst system of CeO2 (ceria) on the Cu(111) substrate. We propose ways to experimentally characterize and control important parameters of the model catalyst—the coverage of the ceria layer, the influence of the Cu substrate, and the density of surface defects on ceria, particularly the density of step edges and the density and the ordering of the oxygen vacancies. The large spectrum of controlled parameters makes ceria on Cu(111) an interesting alternative to a more common model system ceria on Ru(0001) that has served numerous catalysis studies, mainly as a support for metal clusters. 相似文献
13.
L. L. Morselli L. Manetti C. Cosci C. Sardella F. Bogazzi C. Faldini E. Martino M. Gasperi 《Journal of orthopaedics and traumatology》2006,7(4):169-175
Growth hormone (GH) is fundamental for the maintenance of bone mass and metabolism both during childhood and in adulthood.
This effect is due to a complex interaction between circulating GH and IGF-I produced peripherally. In vitro data and experimental
animal models have clarified many of the regulatory mechanisms underlying the characteristic skeletal changes occurring in
acromegaly. This review focuses on the effects of GH excess on bone metabolism and mass in acromegalic patients and, in particular,
on the influence of factors such as hypogonadism, gender, age and therapy on bone metabolism and arthropathy. 相似文献
14.
15.
目的 通过测定生长激素缺乏症 (GHD)患儿用国产重组人生长激素 (recom bined hum angrowth horm one,rh GH)治疗时血清生长激素抗体 (GH- Ab)水平及其结合特性 ,探讨 rh GH的免疫原性及其对疗效的影响。方法 对 6 1例 (男 49例 ,女 12例 ) GHD患儿用国产 rh GH治疗 ,每晚睡前皮下注射 rh GH 0 .1IU /kg共6个月 ;用放射免疫法测定治疗期间患儿血清 GH- Ab水平和滴度 ,并计算抗体结合容量、亲和常数 (Ka)。结果 48%患儿 (2 9/6 1)用药后 3个月血清 GH - Ab呈阳性至试验结束时仍未消失 ,其中 2 0例抗体为弱阳性 (结合率 <10 % ) ,9例呈强阳性 (结合率 >15 % ) ;5 2 %患儿 (32 /6 1)治疗期间抗体为阴性 ;血清 GH- Ab的结合容量、Ka及滴度均为低水平 ,分别为 (0 .1~ 4.8) pmol/L、(1.7× 10 7~ 6 .5× 10 8) L /mol和 1∶ 4~ 1∶ 8。GH- Ab阳性患儿治疗后的身高、身高增长速率及身高落后于正常 SD值的变化与同期阴性者比较无统计学差异 (P>0 .0 5 )。结论 本试验所用国产 rh GH对 GHD患儿身高增长具有确切的促进作用 ,其免疫原性所导致产生的 GH - Ab未对患儿体格线性增长产生负性影响 相似文献
16.
T. A. Mustoe M.D. L. B. Kaban J. B. Mulliken 《European journal of plastic surgery》1987,10(4):135-138
Summary A group of thirty children with nasal fractures was evaluated retrospectively by means of a questionnaire and hospital records. Age at the time of injury ranged from age 3 to 12 (mean = 8.6) years and mean follow-up period was 9 years. Eight patients reported some degree of nasal obstruction post reduction, but only one patient required submucous resection and two patients underwent septorhinoplasty for appearance. No patients reported class III malocclusion, or required orthodontic treatment or maxillofacial corrective surgery for maxillary hypoplasia. We concluded that a childhood nasal fracture treated by closed reduction does not have deleterious effects on facial or nasal growth.This work was supported in part by the Brigham Surgical Group Foundation, Inc., Boston, Massachusetts, USA 相似文献
17.
Mikael Hellström Bo Jacobsson Ulf Jodal Jan Winberg Anders Odén 《Pediatric nephrology (Berlin, Germany)》1987,1(3):269-275
This study presents the result of 12–21 years' follow-up in a group of children with neonatal urinary tract infection (onset within 1 month after birth) in whom early renal growth retardation was noted without concomitant classical renal scarring. In all cases the neonatal infection was diagnosed and treated within a few days of onset and the patients were closely supervised thereafter. Renal length, parenchymal thickness and area were measured at urography. At first follow-up (22 children, mean age 4.1 years) a significant reduction of renal parenchymal thickness was noted. Long-term follow-up (18 patients, mean age 17 years) demonstrated a normalization of renal size in the entire group, although less complete in the subgroup with reflux. There were two major findings in the present study. Firstly, renal growth retardation was seen after neonatal infection, both with and without reflux. Secondly, normalization of renal size in previously small kidneys was demonstrated, suggesting that growth retardation can be a reversible phenomenon. The tendency for such normalization was slightly more marked in children without reflux. Reduction of parenchymal thickness without calyceal deformity, therefore, does not necessarily mean irreversible damage, and differentiation between permanent scarring and temporary growth retardation can thus only be made at later follow-up, possibly not until after puberty. The demonstration of renal growth retardation in spite of early diagnosis and treatment emphasizes the great vulnerability of the kidney in the newborn. 相似文献
18.
Olgierd Pucilowski W. Danysz D.H. Overstreet A.H. Rezvani B. Eichelman D.S. Janowsky 《Brain research bulletin》1991,26(4):621-625
The Flinders Sensitive Line (FSL) of rats has been selectively bred to have increased sensitivity to cholinergic agonists. However, these rats exhibit altered responsiveness to a number of noncholinergic agents, such as apomorphine, buspirone and ethanol. This study compared the FSL and control Flinders Resistant Line (FRL) rats in terms of their hyperthermic response to the phencyclidine (PCP) receptor agonist, MK-801 (0.2 mg/kg SC) and their MK-801 binding characteristics. We have found that FSL rats react with a delayed hyperthermia, having a significantly lower hyperthermia for the first 120 min of observation. Thereafter the response does not differ in FSL and FRL rats. Both groups had similar affinities and numbers of [3H]MK-801 binding sites in the hippocampus/cerebral cortex. Pretreatment with scopolamine (1 mg/kg SC) failed to affect MK-801-induced hyperthermia in either line of rats. These findings suggest that selective breeding of FSL rats attenuated the secondary mechanisms involved in the PCP receptor-mediated hyperthermic response. However, by itself cholinergic supersensitivity does not appear to be a major factor in the blunted responsiveness of FSL rats to MK-801. 相似文献
19.
Implantable Transvenous Pacing Leads: 总被引:1,自引:0,他引:1
With the dawn of a new millennium, physicians' demands for very thin transvenous leads able to be positioned in nontraditional sites like the Bachmann's bundle, the high and mid-right ventricular septum, and the His bundle have created new and exciting challenges for lead engineers. Bipolar leads can now be as thin and reliable as unipolar leads. Cathode electrodes are very small, porous, and demonstrate high impedance. To optimize stimulation thresholds, steroid-eluting passive- and active-fixation electrodes have become popular for use in the atrium and ventricle. To create thin lead body diameters, new insulation and conductor materials and lead body designs are necessary. Hybrid medical materials having the best features of silicone rubber and polyurethane will allow for reliable insulation. Conductor cables instead of helical coils permit strong thin diameter leads to be designed. Transvenous lead implantation using the traditional stylet may not be possible with thin diameter leads, necessitating the use of sophisticated workstations using steerable catheters to guide these new active-fixation leads to selective sites in the right heart. The pacing lead of the future may be very different from the one used today. Ironically, it will have features and implantation techniques similar to the transvenous leads designed prior to the use of the stylet. We are now approaching full circle in lead development, retracing the footprints of the early implanters of three and a half decades ago. (PACE 2004; 27[Pt. II]:887–893) 相似文献
20.
逆转录-聚合酶链反应(RT-PCR)法是将PCR方法与逆转录法结合应用,可快速高效地扩增某一基因的全cDNA。类胰岛素生长因子-I(IGF-I)在人染色体中只有一个基因,全长超过45kb,并有内含子,其cDNA却只有几百个bp,为了表达得到IGF-I,本文利用RT-PCR方法,从胎肝提出的混合mRNA中,筛选并扩增了IGF-I的cDNA。经过分子克隆与测序,证明不需制备胎肝cDNA库,即可快速获得IGF-I的cDNA。 相似文献