全文获取类型
收费全文 | 37937篇 |
免费 | 3245篇 |
国内免费 | 1349篇 |
专业分类
耳鼻咽喉 | 487篇 |
儿科学 | 740篇 |
妇产科学 | 664篇 |
基础医学 | 4641篇 |
口腔科学 | 639篇 |
临床医学 | 4088篇 |
内科学 | 6592篇 |
皮肤病学 | 884篇 |
神经病学 | 2526篇 |
特种医学 | 1219篇 |
外国民族医学 | 13篇 |
外科学 | 5008篇 |
综合类 | 4053篇 |
现状与发展 | 4篇 |
一般理论 | 20篇 |
预防医学 | 2353篇 |
眼科学 | 1320篇 |
药学 | 3209篇 |
18篇 | |
中国医学 | 1134篇 |
肿瘤学 | 2919篇 |
出版年
2024年 | 58篇 |
2023年 | 464篇 |
2022年 | 935篇 |
2021年 | 1720篇 |
2020年 | 1216篇 |
2019年 | 1191篇 |
2018年 | 1350篇 |
2017年 | 1140篇 |
2016年 | 1140篇 |
2015年 | 1442篇 |
2014年 | 1804篇 |
2013年 | 1808篇 |
2012年 | 2750篇 |
2011年 | 2775篇 |
2010年 | 1558篇 |
2009年 | 1333篇 |
2008年 | 1993篇 |
2007年 | 2025篇 |
2006年 | 1961篇 |
2005年 | 1969篇 |
2004年 | 1457篇 |
2003年 | 1295篇 |
2002年 | 1143篇 |
2001年 | 952篇 |
2000年 | 947篇 |
1999年 | 904篇 |
1998年 | 490篇 |
1997年 | 419篇 |
1996年 | 313篇 |
1995年 | 312篇 |
1994年 | 252篇 |
1993年 | 183篇 |
1992年 | 351篇 |
1991年 | 330篇 |
1990年 | 330篇 |
1989年 | 287篇 |
1988年 | 240篇 |
1987年 | 229篇 |
1986年 | 219篇 |
1985年 | 173篇 |
1984年 | 128篇 |
1983年 | 83篇 |
1982年 | 56篇 |
1981年 | 59篇 |
1979年 | 79篇 |
1978年 | 60篇 |
1977年 | 56篇 |
1974年 | 68篇 |
1973年 | 66篇 |
1972年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
双氢杨梅树皮素对兔胸主动脉条平滑肌收缩反应的影响 总被引:1,自引:0,他引:1
用兔胸主动脉条研究双氢杨梅树皮素对去甲肾上腺素(NE)、KCl和CaCl2所致兔胸主动脉条收缩反应量效曲线的影响。双氢杨梅树皮素能显著地抑制NP、KCl和CaCl2所致兔胸主动脉杂的收缩,量效曲线右移,最大反应降低,对高K 所致兔胸主动脉条收缩的抑制作用明显大于NE所致兔胸主动脉条收缩的抑制作用。双氢杨梅树皮素对NE引起的依赖内Ca2 释放的收缩有明显抑制作用,而对NE依赖细胞外Ca2 性收缩区在较高浓度时才显示抑制作用,提示双氢杨梅树皮素可能对电压依赖性钙通道(PDC)有选择性阻滞作用。 相似文献
132.
133.
H Yamanaka E H Willis C A Penning C L Peebles E M Tan D A Carson 《The Journal of clinical investigation》1987,80(3):900-904
The chromatin-bound enzyme poly(ADP-ribose) polymerase (ADPRP) is strongly stimulated by DNA with single- or double-stranded breaks, and transfers the ADP-ribose moiety of NAD to nuclear proteins. The activation of ADPRP is important for DNA repair and replication, and also has been postulated to play a role in the pathogenesis of lymphocyte dysfunction associated with chronic inflammatory diseases, and inborn errors of nucleoside metabolism. We have detected high titers of IgG autoantibodies to the ADPRP protein in six patients with rheumatic complaints. No other autoantibodies were detected in any of the six sera. The specificity of the anti-enzyme antibodies was established by (a) immunoprecipitation of ADPRP activity, (b) immunoprecipitation and immunoblotting of both the native 116-kD enzyme and its proteolytic digestion products. ADPRP was purified from human thymus and calf thymus. The autoantibodies reacted equivalently with both enzymes. The anti-ADPRP antibodies had a distinctive immunofluorescent pattern with HEp-2 cells, reacting intensely with nucleoli and metaphase chromosomes, and diffusely with the nucleus. Autoantibodies to ADPRP have not been described previously. The presence of a specific immune response against an enzyme that has been associated with various immunodeficiency syndromes raises intriguing possibilities concerning the relationship between DNA damage, immunodeficiency, and autoimmunity. 相似文献
134.
E C Tan 《The Journal of dermatologic surgery and oncology》1989,15(3):270-272
The punch technique of repairing pierced earlobe deformities is a practical and simplified alternative to the usual method of repair. The procedure can easily be performed in any dermatology office since the instruments required are very basic. The technique is presented in a series of illustrations, and the results are cosmetically acceptable. 相似文献
135.
Expression of antibody heavy- and light-chain genes by transfection permits the production of monoclonal antibodies with improved biological and antigen-binding properties. The immunoglobulin genes are placed in vectors containing a gene for encoding a protein that provides a biochemically selectable function in eukaryotic cells; these vectors are transfected into myeloma and hybridoma cells. Selection of drug-resistant cells permits the efficient isolation of the rare cells that express the transfected DNA. By placing heavy and light chains on plasmids with different selectable markers, one can deliver heavy- and light-chain genes simultaneously to the same cell. The transfected immunoglobulin genes are efficiently expressed and the proteins produced are a faithful mirror of the genes that were introduced. Using the standard techniques of genetic engineering and gene transfection, we can now produce antibodies of widely varying structures, including chimeric antibodies with segments derived from different species. These antibodies provide useful reagents to study structure-function relationships within the antibody molecule. Ultimately it will be possible to produce a new generation of antibody molecules with improved antigen-binding properties and effector functions. 相似文献
136.
Rabies in Malaysia 总被引:1,自引:0,他引:1
Y S Tan 《The Southeast Asian journal of tropical medicine and public health》1988,19(4):535-536
137.
Yew-Long Lo Yang-Fang Dan Teng-Hee Leoh Yam-Eng Tan Siti Nurjannah Pavanni Ratnagopal 《Journal of clinical neurophysiology》2004,21(2):110-113
Repetitive nerve stimulation (RNS) is a simple and rapid method for evaluation of neuromuscular transmission defects. Although the effect of exercise in conjunction with RNS is well recognized, it has not been standardized in actual patient and control groups. In a prospective study over a period of 1 year, the authors evaluated the effect of exercise in conjunction with RNS in comparison with conventional 3-Hz RNS at rest in the clinical setting. Fifty-four patients who were referred for possible neuromuscular transmission disorders, in addition to 35 healthy control subjects, were studied. Amplitude and area decremental responses with RNS at rest and after 20 seconds of maximal exercise at 1-minute intervals up to 3 minutes were evaluated. The use of RNS with exercise resulted in additional diagnostic yield of up to 36.4% compared with conventional 3-Hz RNS at rest. The standardized use of exercise with RNS is advocated for increasing its diagnostic yield in the neurophysiologic laboratory. 相似文献
138.
Nucleotide polymorphism in colicin E1 and Ia plasmids from natural isolates of Escherichia coli. 总被引:2,自引:0,他引:2 下载免费PDF全文
M A Riley Y Tan J Wang 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(23):11276-11280
We examined DNA sequence polymorphism for the colicin gene clusters of seven ColE1 and six ColIa plasmids obtained from natural isolates of Escherichia coli. These gene clusters harbor levels of nucleotide diversity ranging from 0.006 (ColIa) to 0.054 (ColE1). This level of diversity is similar to that observed for chromosomally encoded E. coli genes. However, the variance associated with these estimates is severalfold higher for the plasmid-encoded genes. This increased variance may be due to the differing plasmid population sizes. The pattern of colicin gene cluster polymorphism suggests that the two colicins are evolving in different fashions. ColE1 accumulates polymorphism at an elevated rate in the central domain of the colicin protein, while ColIa polymorphism is distributed evenly along the gene cluster. Comparison of the patterns of divergence between colicin and related proteins of ColIa and Ib and patterns of polymorphism within ColIa suggest that this gene cluster is not evolving in a neutral fashion. These data lend support to the hypothesis that colicin gene clusters may evolve under the influence of diversifying selection. 相似文献
139.
Linda G. Rabinowitz M.D. Nancy B Esterly M.D. Ilona J. Frieden M.D. Gregory S. Garbin M.D. Roy C. Grekin M.D. T. J. Stafford M.D. Ph.D. O. T. Tan M.D. Linda G. Rabinowitz M.D. Gerald N. Goldberg M.D. Karen F Rothman M.D. Lynne J. Roberts M.D. Roy G. Geronemus M.D. Susan B. Mallory M.D. Jerome M. Garden M.D. Joseph G. Morelli M.D. Moise L Levy M.D. Bernard A. Cohen M.D. 《Pediatric dermatology》1992,9(2):132-153
One of the most exciting developments in pediatric dermatology has been the use of the flashlamp-pumped, 585-nm, pulsed dye laser for treatment of vascular birthmarks. In many cases the results are miraculous. The increase in self-esteem and happiness of many children and adolescents has been overwhelming; for some, depression has been lifted, stuttering has ceased, social involvement has increased, and antidepressants have been discontinued. There are many success stories to tell.
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser. 相似文献
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser. 相似文献
140.
C Damase-Michel G Tavernier M E Llau F Chollet J M Sénard H Bagheri M A Tran G Houin B Guiraud-Chaumeil J L Montastruc 《Archives des maladies du coeur et des vaisseaux》1992,85(8):1149-1151
Several authors have discussed an alteration of adrenergic receptivity in arterial hypertension. De Champlain (Hypertension 1990; 8: S77-S85) suggested that postsynaptic alpha 1-adrenergic functions became dominant while beta-adrenergic functions are attenuated in arterial hypertension. However, the status of presynaptic alpha 2-adrenoceptors remains unknown. The present study investigates presynaptic alpha 2-adrenoceptors in hypertension through the measurement of plasma levels of noradrenaline after administration of yohimbine, an alpha 2-adrenoceptor antagonist, in essential hypertension. Yohimbine (0.2 mg/kg per os) induced a 73% increase of plasma levels of noradrenaline in hypertensive patients (n = 12) and a 178% one in normotensive subjects (n = 6, p < 0.05). A similar significant difference was found in experimental neurogenic hypertension observed in awake dogs 3 weeks after sinoaortic denervation: the increase in plasma concentrations of noradrenaline after yohimbine (0.5 mg/kg i.v.) was +279% in hypertensive versus +642% in normotensive dogs (p < 0.05). The results show that the magnitude of the yohimbine-induced sympathetic activation is lower in hypertensives than in normotensives. They suggest the existence of a presynaptic alpha 2-adrenoceptor desensitization in arterial hypertension. The abnormality of this presynaptic inhibitory mechanism can increase the sympathetic tone and help to develop and maintain arterial hypertension. 相似文献