全文获取类型
收费全文 | 5779篇 |
免费 | 408篇 |
国内免费 | 204篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 32篇 |
妇产科学 | 45篇 |
基础医学 | 703篇 |
口腔科学 | 371篇 |
临床医学 | 269篇 |
内科学 | 1477篇 |
皮肤病学 | 122篇 |
神经病学 | 200篇 |
特种医学 | 173篇 |
外科学 | 441篇 |
综合类 | 568篇 |
现状与发展 | 1篇 |
预防医学 | 682篇 |
眼科学 | 62篇 |
药学 | 783篇 |
4篇 | |
中国医学 | 296篇 |
肿瘤学 | 142篇 |
出版年
2024年 | 11篇 |
2023年 | 85篇 |
2022年 | 344篇 |
2021年 | 401篇 |
2020年 | 198篇 |
2019年 | 175篇 |
2018年 | 227篇 |
2017年 | 225篇 |
2016年 | 235篇 |
2015年 | 228篇 |
2014年 | 357篇 |
2013年 | 466篇 |
2012年 | 289篇 |
2011年 | 375篇 |
2010年 | 304篇 |
2009年 | 265篇 |
2008年 | 244篇 |
2007年 | 249篇 |
2006年 | 207篇 |
2005年 | 176篇 |
2004年 | 150篇 |
2003年 | 145篇 |
2002年 | 116篇 |
2001年 | 115篇 |
2000年 | 72篇 |
1999年 | 81篇 |
1998年 | 79篇 |
1997年 | 74篇 |
1996年 | 53篇 |
1995年 | 52篇 |
1994年 | 58篇 |
1993年 | 48篇 |
1992年 | 29篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 29篇 |
1984年 | 13篇 |
1983年 | 28篇 |
1982年 | 14篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
排序方式: 共有6391条查询结果,搜索用时 0 毫秒
1.
Scleroderma is a chronic disease that has been associated with immune dysfunction. One of the oral manifestations is microsomia, a result of collagen deposition in the perioral tissues. The complexity of treating these patients includes limited mouth opening ability, and difficulty inserting and removing dentures due to finger deformity. This article will describe an appliance specially designed especially for scleroderma patients, which facilitates treatment of the patient with removable partial dentures (RPD). 相似文献
2.
Jean-Fran ois Marini Fran oise Pons Jocelyne Leger Nathalie Loffreda Monique Anoal Martine Chevallay Michel Fardeau Jean J. Leger 《Neuromuscular disorders : NMD》1991,1(6):397-409
The expression of MHC isoforms in the skeletal muscles of nine patients with Duchenne muscular dystrophy (DMD) (from 2.5 to 15 yr of age) and three DMD carriers was studied using different specific anti-MHC MAbs. We also analyzed muscle fiber size and fiber reactivity with acridine orange and/or with a surface antigen marker. One-quarter of all fibers of DMD patients, or less with age, were of normal size and contained only adult slow MHC. Half of the muscle fibers contained adult and developmental MHCs. Only half of these fibers were representative of an active regenerative process. MHC co-expression also altered the proportion of normal fast or slow fibers. Adult fast MHCs were expressed as unique MHC only in small and very small fibers in the oldest DMD patients. In DMD carrier muscles, the greatest alterations in MHC expression were observed in patients with the most reduced dystrophin expression. However, MHC changes in dystrophin-positive fibers were similar to those observed in dystrophin-free fibers. In conclusion, disruptions or delays in the switching of all genes coding for adult fast and slow MHC and developmental MHC coincided with dystrophin deletion and with perturbations in its expression. 相似文献
3.
应用蒙特卡洛法仿真辐射式金属换热器内的辐射传热过程,建立了换热器综合传热的数学模型,利用概率论原理,把辐射能迁移过程仿真为一定累积概率分面下的随机过程,该模型能较好地反映换热器内传热过程的真实情况,可以计算出换热器内烟气、筒壁、空气的温度和壁面热流分布,以及研究烟气进口温度、换热器筒径和狭逢宽度对换热效果的影响。 相似文献
4.
T. Ariga Y. Sakiyama K. Tomizawa S. Imajoh-Ohmi S. Kanegasaki S. Matsumoto 《European journal of pediatrics》1993,152(6):469-472
Molecular genetic analysis was performed in a patient with cytochrome b positive X-linked chronic granulomatous disease. A previous Southern blot study, using a cytochrome b heavy chain cDNA as probe, revealed a Pst I restriction fragment pattern for the cytochrome b heavy chain gene (CYBB) different to that of normal individuals. Since restriction length polymorphism with Pst I has never been observed in control individuals and no abnormal restriction fragment patterns in the patient's CYBB was detected with seven other enzymes used, we focussed on the single Pst I site in the CYBB cDNA as being the only mutation site responsible for his disease. A fragment of the patient's cDNA which included the Pst I site was amplified by reverse polymerase chain reaction, and loss of the Pst I site in the fragment was confirmed by incubation with Pst I. Subsequent sequence analysis of the fragment revealed a point mutation in the Pst I site (cytosine to adenine), substituting glutamic acid for alanine at position 57. 相似文献
5.
Wallin C.-J. B.; Jacobson S. H.; Leksell L. G. 《Nephrology, dialysis, transplantation》1996,11(11):2269-2275
It has been postulated that patients with chronic renal failure,even in the absence of cardiopulmonary symptoms, accumulateinterstitial pulmonary fluid, which is removed by haemodialysis.To test this hypothesis we used the indocyanine green (ICG)-heavywater double indicator dilution method to measure lung water,cardiac output, and central blood volume in relation to haemodialysis.Ten uraemic patients, without cardiopulmonary symptoms, wereinvestigated at the beginning and end, and 2 h after, a regulardialysis session. A group of 18 surgical patients about to undergoelective abdominal surgery served as controls. Despite normalgas exchange, central blood volume, and cardiac output at thestart of dialysis the mean (SD) lung water was significantlyhigher than in the control group [4.8 (0.9) compared with 3.6(0.7) ml/kg, P<0.001]. There was no correlation between weightgain between sessions of dialysis and the magnitude of lungwater at the start of dialysis. Lung water decreased (P <0.001)to the level of the control group in response to dialysis. Therewas no correlation between weight loss and reduction in lungwater induced by dialysis. In conclusion, we have verified thepresence of subclinical pulmonary oedema which was removed bydialysis in a group of patients with established renal failure.The variations in lung water cannot be explained by hydrostaticmechanisms alone. 相似文献
6.
Reports the case of a 60-year-old woman who underwent R2 total gastrectomy, and subsequent palliation of painful symptom
recurrence via a membrane-covered metal stent.
Received: 13 June 1996/Accepted: 31 July 1996 相似文献
7.
Identifying environmental factors reflected to alcohol use is important for program planning and evaluation in college alcohol and drug prevention programs. Little has been written concerning uses of data in environmental prevention efforts. This paper presents four brief interrelated case studies of how environmental modifications were used by a college alcohol prevention project to 1) change the marketing practices and service policies of a student-oriented bar, 2) alter the sales practices of a campus bookstore concerning alcohol paraphernalia, 3) to develop a campaign with the goal of reducing risk factors related to heavy drinking at private student parties, and 4) stop an unsafe bus from transporting students to bars in Mexico. Creative use of such environmental prevention approaches has potential benefit to colleges and universities concerned with the primary prevention of alcohol-related problems experienced by students. 相似文献
8.
A low concentration of transition metal ions Co2+ and Ni2+ increases the inward current density in neurons from the land snail Helix aspersa. The currents were measured using a single electrode voltage-clamp/internal perfusion method under conditions in which the external Na+ was replaced by Tris+, the predominant external current carrying cation was Ca2+, and the internal perfusate contained 120 mM Cs+/0 K+; 30 mM tetraethylammonium (TEA) was added externally to block K+ current. In the presence of Co2+ (3 mM) or Ni2+ (0.5 mM) inward Ca2+ currents were stimulated normally by voltage-dependent activation of Ca2+ channels. There was a 5-10% decrease in the rate of rise of the inward current. The principal effect of Co2+ and Ni2+ in increasing the current density seems to be a decrease in the rate at which the inward currents decline during a depolarizing voltage pulse. The results may be due to a decrease in a voltage-dependent or Ca(2+)-dependent outward current and/or an inhibition of Ca2+ channel inactivation. Outward current under these conditions (zero internal K+) was significant and most likely due to Cs+ efflux through the voltage-activated or Ca(2+)-activated nonspecific cation channels. Co2+ is an extremely effective blocker of this outward current. These results are not an artifact of internal perfusion or the special ionic conditions. Intracellular recording of unperfused neurons in normal Helix Ringer's solution showed that the Ca(2+)-dependent action potential duration was increased significantly by low concentrations of Co2+. This result is consistant with the Co(2+)-dependent increase in inward (depolarizing) current seen in voltage-clamp experiments. 相似文献
9.
建立了较完整的估计重油和沥青中饱和碳浓度数方法,其中包括环烷桥头碳、环烷甲基取代碳、环烷烷基(≥C2)取代碳等。基于理论分析,建立了估计环间的桥链和各种平均结构参数的方法,包括平均芳环环核数和环烷环环核数、芳环和环烷环烷工取代度、单元片上芳环和环烷环数。从实验数据出发,提出了烷基链长分布的公式。 相似文献
10.
用循环伏安法研究了吡咯在不同金属基底不同支持电解质中的聚合过程,对不同基底上制备的聚吡咯膜进行了电化学、扫描电镜、表面能谱等方面的研究,考察了聚吡咯膜电极对NO_3-离子的电位响应情况,结果表明,不同基底不同支持电解质在不同的吡咯浓度中表现出各异的伏安行为,经电化学处理的聚吡咯膜电极均对NO_3-呈Nernst响应,扫描电镜观察表明除Pt基底外在其它基底上制备的聚吡咯膜均呈颗粒性球状堆集。 相似文献