全文获取类型
收费全文 | 38951篇 |
免费 | 1962篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 595篇 |
儿科学 | 1611篇 |
妇产科学 | 614篇 |
基础医学 | 5088篇 |
口腔科学 | 950篇 |
临床医学 | 2420篇 |
内科学 | 9578篇 |
皮肤病学 | 1319篇 |
神经病学 | 3228篇 |
特种医学 | 957篇 |
外科学 | 5405篇 |
综合类 | 222篇 |
一般理论 | 15篇 |
预防医学 | 3373篇 |
眼科学 | 1130篇 |
药学 | 2323篇 |
中国医学 | 184篇 |
肿瘤学 | 1948篇 |
出版年
2024年 | 39篇 |
2023年 | 279篇 |
2022年 | 185篇 |
2021年 | 968篇 |
2020年 | 448篇 |
2019年 | 1098篇 |
2018年 | 1816篇 |
2017年 | 1047篇 |
2016年 | 863篇 |
2015年 | 734篇 |
2014年 | 860篇 |
2013年 | 1584篇 |
2012年 | 2901篇 |
2011年 | 3290篇 |
2010年 | 1529篇 |
2009年 | 850篇 |
2008年 | 2560篇 |
2007年 | 2626篇 |
2006年 | 2379篇 |
2005年 | 2453篇 |
2004年 | 2280篇 |
2003年 | 2210篇 |
2002年 | 1998篇 |
2001年 | 1407篇 |
2000年 | 1834篇 |
1999年 | 935篇 |
1998年 | 217篇 |
1997年 | 129篇 |
1996年 | 129篇 |
1995年 | 106篇 |
1994年 | 83篇 |
1993年 | 82篇 |
1992年 | 111篇 |
1991年 | 97篇 |
1990年 | 79篇 |
1989年 | 77篇 |
1988年 | 72篇 |
1987年 | 53篇 |
1986年 | 31篇 |
1985年 | 55篇 |
1984年 | 58篇 |
1983年 | 50篇 |
1982年 | 40篇 |
1981年 | 30篇 |
1980年 | 33篇 |
1978年 | 33篇 |
1977年 | 22篇 |
1976年 | 21篇 |
1975年 | 21篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
The cellular uptake and intracellular distribution of the essential but highly toxic nutrient, copper, is a precisely orchestrated process. Copper homeostasis is coordinated by several proteins to ensure that it is delivered to specific subcellular compartments and copper-requiring proteins without releasing free copper ions that will cause damage to cellular components. Genetic studies in prokaryotic organisms and yeast have identified membrane-associated proteins that mediate the uptake or export of copper from cells. Within cells, small cytosolic proteins, called copper chaperones, have been identified that bind copper ions and deliver them to specific compartments and copper-requiring proteins. The identification of mammalian homologues of these proteins reveal a remarkable structural and functional conservation of copper metabolism between bacteria, yeast and humans. Furthermore, studies on the function and localization of the products of the Menkes and Wilson's disease genes, which are defective in patients afflicted with these diseases, have provided valuable insight into the mechanisms of copper balance and their role in maintaining appropriate copper distribution in mammals. 相似文献
142.
Alonso M Barriuso T Castañeda MJ Díaz-Caneja N Gutiérrez I Sarmiento JJ Villar E 《Health physics》1999,76(4):388-392
A method to estimate the absorbed dose to organs in diagnostic radiology was developed. The method is based on Monte Carlo techniques and has been prepared as a tool that can be adapted to any type of examination or view and which is readily available since it is used in a personal computer and not as a list of numerical results. It has been developed with the EGS4 system for static examinations in diagnostic radiology. A study was made of the absorbed doses to different parts of the head during a conventional x-ray examination. Simulation was performed for different arrangements (monoenergetic beam, spectrum, different number of histories, different size of cells, etc.). The method is capable of estimating doses in agreement with those measured experimentally and those obtained by other authors. 相似文献
143.
Cordeiro R Peñaloza ER Cardoso CF Cortez DB Kakinami E Souza JJ Souza MT Fernandes RA Guercia RF Adoni T 《Cadernos de saúde pública / Ministério da Saúde, Funda??o Oswaldo Cruz, Escola Nacional de Saúde Pública》1999,15(4):719-728
The aim of this paper was to evaluate the accuracy of data on death certificates for occupation and main cause of death. Measure of agreement was assessed comparing data from death certificates with those from both medical records and next-of-kin interviews, analyzing information for 552 residents of Botucatu, Southeast Brazil, who died in 1997. Kappa coefficients of 0.31 (95% C.I. 0. 29-0.34) and 0.76 (95% C.I. 0.75-0.76) were obtained for data on occupation and main cause of death, coded by a Brazilian two-digit classification and the three-digit ICD-10 classification, respectively. One can conclude that, although quality of the main cause of death is acceptable for pilot studies, data on occupation taken only from death certificates is not accurate enough to be used in epidemiological research. 相似文献
144.
The nutritional status of patients can be evaluated by monitoring changes in body composition, including the depletion of protein and muscle, adipose tissue distribution and changes in hydration status, bone or cell mass. Neutron activation analysis is a unique reference tool for the in-vivo determination of body composition. In this review we describe the recent changes in the field that followed the advent of new portable generators of fast neutrons, capable of performing elemental analysis in the clinical environment. New models were developed based on the partition of the measurable elements of the body. The recent developments help evaluate new treatments for wasting and obesity, in which change in body composition is the main outcome. 相似文献
145.
Regulated commitment of TNF receptor signaling: a molecular switch for death or activation 总被引:14,自引:0,他引:14
Tumor necrosis factor receptor (TNFR) superfamily members can induce a context-dependent apoptosis or cell activation. However, the mechanisms by which these opposing programs are selected remain unclear. We show that in T cells, TNFR2 (TNFRSF1B) signaling is dramatically affected by the intracellular mediator RIP, a protein Ser/Thr kinase required for NF-kappaB activation by TNFR1 (TNFRSF1A). In the presence of RIP, TNFR2 triggers cell death, whereas in the absence of RIP, TNFR2 activates NF-kappaB. RIP is induced during IL2-driven T cell proliferation, and its inhibition reduces susceptibility to TNF-dependent apoptosis. Evidence that signaling outputs are shaped by intracellular constraints helps reconcile conflicting views of TNFR1 and TNFR2 as apoptotic mediators. 相似文献
146.
Baños N Planas JV Gutiérrez J Navarro I 《Comparative biochemistry and physiology. Part C, Pharmacology, toxicology & endocrinology》1999,124(1):33-40
In this study we report that the use of a heterologous radioimmunoassay (RIA) is valid for the detection of insulin-like growth factor-I (IGF-I) levels in plasma of a variety of fish species. Parallelism between standard curves and plasma dilutions were observed and the standard curve obtained with mammalian IGF-I presented the same characteristics as that obtained with coho salmon recombinant IGF-I.The RIA was biologically validated since total plasma IGF-I values were significantly modified by different experimental conditions. Hyperinsulinemia induced either by arginine or insulin injection was accompanied by increases in IGF-I plasma levels in brown trout (Salmo trutta). In contrast, parallel decreases in insulin and IGF-I circulating levels were observed after 45 days of fasting and 20 days after a single streptozotocin injection. Administration of arginine in fasted fish led to a relative increase in insulin and IGF-I plasma concentrations, while arginine injection in fish previously treated with streptozotocin increased IGF-I levels only. The above data suggest that insulin, together with other factors, may act to increase the levels of IGF-I in plasma. 相似文献
147.
Martínez-Gomis J Fernández-Solanas A Viñas M González P Planas ME Sánchez S 《Archives of oral biology》1999,44(11):901-906
Four groups of rats were inoculated with Streptococcus sobrinus ATCC 33478 and fed a cariogenic diet for 42 days. Topical treatment with either distilled water, sodium fluoride (0.2%), a solution containing lactoferrin and lactoperoxidase, or a solution containing liposome-encapsulated lactoferrin and liposome-encapsulated lactoperoxidase was applied at intervals for 35 days. Caries incidence in groups treated with liposome-encapsulated lactoferrin and lactoperoxidase was significantly lower than in control groups. The number of viable Strep. sobrinus and the proportion of Strep. sobrinus in the total counts were significantly higher in liposome-treated groups. Free lactoferrin and lactoperoxidase did not cause a significant reduction in caries incidence. 相似文献
148.
During a survey of the occurrence of Malassezia species in the external ear canals of cats without otitis externa, Malassezia furfur was isolated. This is the first report of the isolation of M. furfur from cats. 相似文献
149.
Szmidt-Sałkowska E Rowiñska-Marciñska K Fidziañska A Hausmanowa-Petrusewicz I 《Electromyography and clinical neurophysiology》1999,39(2):87-92
The aim of present study was to analyse possible myopathic changes in the muscles of manifesting carriers of Duchenne Muscular Dystrophy (DMD) using concentric needle emg and macroemg methods. Our material consisted of 10 manifesting carriers aged 9-52 (mean 30 years) and 20 healthy age-matched females. Concentric needle emg (CNEMG) and macroemg was performed in biceps brachii (BB) muscle in both groups: carriers and controls. Myopathic changes were observed in BB muscle in 5 of 10 manifesting carriers using CNEMG and in all cases (10 carriers) using macroemg method. Macro electrode, which reflects total motor unit activity, i.e., the total number and size of component muscle fibres, supplies information about early myogenic lesion of the muscle. Therefore the macroemg seems to be a sensitive and useful electrophysiological diagnostic method in carriers of DMD. 相似文献
150.
Aguirre-Zorzano LA Estefanía-Cundín E Gil-Lozano J Martínez-Conde R Núñez-Antón V Santamaría-Zuazua J 《The International journal of periodontics & restorative dentistry》1999,19(4):363-371
The safety and bone-regenerative capacity of a resorbable membrane (Resolut) was evaluated by a nonrandomized prospective clinical study of patients with periodontal defects. Prior to surgical management all patients underwent scaling and root planing and were instructed on oral hygiene. The study included 18 patients (31 periodontal defects) who received surgical treatment by guided tissue regeneration (GTR) using resorbable membranes. The results were evaluated 12 months after surgery in terms of Plaque Index, bleeding index, probing depth, gingival recession, clinical attachment level, and dental mobility. The results obtained show that the use of resorbable membranes in GTR causes few complications. The mean gain in clinical attachment level (4.06 +/- 1.91 mm), with an attachment level gain of more than 3 mm in 81.2% of the defects, suggests the presence of "new attachment." This difference was clinically and statistically significant (t = 11.03, P = 0). The multivariate regression study showed that 60% of the observed variability (F = 11.48, P < 0.001) in clinical attachment level gain was accounted for by the variable's initial probing depth, the Plaque Index of the tooth subjected to GTR, and the infrabony component of the defect. 相似文献