全文获取类型
收费全文 | 8053篇 |
免费 | 312篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 203篇 |
儿科学 | 210篇 |
妇产科学 | 441篇 |
基础医学 | 1253篇 |
口腔科学 | 102篇 |
临床医学 | 450篇 |
内科学 | 1899篇 |
皮肤病学 | 188篇 |
神经病学 | 609篇 |
特种医学 | 206篇 |
外国民族医学 | 1篇 |
外科学 | 785篇 |
综合类 | 51篇 |
一般理论 | 1篇 |
预防医学 | 466篇 |
眼科学 | 195篇 |
药学 | 846篇 |
中国医学 | 42篇 |
肿瘤学 | 464篇 |
出版年
2023年 | 29篇 |
2022年 | 109篇 |
2021年 | 195篇 |
2020年 | 72篇 |
2019年 | 102篇 |
2018年 | 183篇 |
2017年 | 161篇 |
2016年 | 176篇 |
2015年 | 212篇 |
2014年 | 313篇 |
2013年 | 389篇 |
2012年 | 604篇 |
2011年 | 625篇 |
2010年 | 321篇 |
2009年 | 240篇 |
2008年 | 464篇 |
2007年 | 493篇 |
2006年 | 535篇 |
2005年 | 495篇 |
2004年 | 521篇 |
2003年 | 472篇 |
2002年 | 442篇 |
2001年 | 187篇 |
2000年 | 194篇 |
1999年 | 119篇 |
1998年 | 45篇 |
1997年 | 31篇 |
1996年 | 22篇 |
1995年 | 23篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 24篇 |
1991年 | 31篇 |
1990年 | 28篇 |
1989年 | 20篇 |
1988年 | 34篇 |
1987年 | 30篇 |
1986年 | 29篇 |
1985年 | 33篇 |
1984年 | 24篇 |
1983年 | 23篇 |
1982年 | 24篇 |
1981年 | 16篇 |
1979年 | 29篇 |
1978年 | 19篇 |
1977年 | 24篇 |
1975年 | 38篇 |
1974年 | 19篇 |
1973年 | 19篇 |
1971年 | 22篇 |
排序方式: 共有8412条查询结果,搜索用时 15 毫秒
41.
Spatial adjacency of stimulus source and response site has been proven important for learning of simple behavioural tasks, including auditory quality and location discrimination. We investigated effect of sound source position (adjacent or not adjacent to manipulanda) on learning and performance of a complex auditory recognition memory task. Spatial adjacency of stimuli and manipulanda improved learning of a simple auditory directional task, which was an intermediate stage of training. In contrast, no improvement of learning and performance of the recognition task was found. 相似文献
42.
Remiszewski P Langfort R Podsiadło B Kuś J Płodziszewska M Radzikowska E Roszkowska B Szopiński J Tomkowski W Wawrzyńska L Wiatr E Wierzbicka M Załeska J Załeska M Zych J Rowińska-Zakrzewska E 《Pneumonologia i alergologia polska》2002,70(5-6):251-257
The aim of this paper is an analysis of clinical documentation and results of autopsy of 21 patients (pts) who died of invasive aspergillosis (IA) in the Institute of Tuberculosis and Chest Diseases in years 1993-2000 and the assessment of predisposing factors for IA. In 17 pts IA was the main and in other 4 only an accessory cause of death. All pts were treated with corticosteroids and/or cytostatic drugs--because of lung cancer (11 pts), cancer in other site (2 pts), haematologic disorders (2 pts), Wegener's granulomatosis (1 pt), polymyositis (1 pt), idiopathic pulmonary fibrosis (1 pt) and other diseases (3 pts). In 15 out of 21 pts granulocytopenia was revealed (from 0.008 x 10(9)/L to 0.82 x 10(9)/L) on an average one month before death. In 15 pts IA was limited to the lungs, in 6 others there were also fungal lesions in brain, kidneys, liver, spleen and heart. Pts with disseminated form of IA had significantly lower granulocyte count and were treated with higher doses of corticosteroids than others. Immunosuppressive drugs and granulocytopenia can be regarded as predisposing factors. Fatal course of IA depended also on the late diagnosis. 相似文献
43.
Janina Wyczołkowska Annie Prouvost-Danon Czesław Maśliński 《Inflammation research》1986,18(1-2):172-175
The conditions for active sensitization of hamster peritoneal and pleural mast cells and IgE-induced histamine release as well as cell desensitization were defined. Immunization of hamsters with ovalbumin (5 g) in Al/OH/3 gel (5 mg) with several boosters resulted in sensitization of peritoneal and pleural mast cells; in the presence of extracellular Ca++, pH of medium 7.2 and at 37°C these cells released up to 70% of histamine on the challenge with specific antigen. Partial release was observed when the cells were challenged with antigen in the absence of extracellular calcium. The rate of release is high during the first seconds of activation and is complete at 1 min. 30 min preincubation of peritoneal and pleural mast cells in calcium-free conditions (in the presence of 4 mM EDTA) resulted in complete desensitization of cells to subsequent action of antigen in potimal conditions. The present experiments demonstrate, that hamster peritoneal and pleural mast cells can be a useful model system forin vitro studies of the mechanisms of IgE-induced cell activation. 相似文献
44.
Lynch G Kohler S Leser J Beil M Garcia-Marin LJ Lutz MP 《Pflügers Archiv : European journal of physiology》2004,448(4):445-451
The aim of this study was to establish whether the rate of fatty acid (FA) incorporation and its utilization by the isolated soleus muscle is modified under conditions of thyroid hormone deficit or excess. The rate of palmitic acid (PA) uptake, oxidation and incorporation into intramuscular lipids with increasing PA concentration (0.5–1.5 mM) in the incubation medium were determined. In hypothyroid rats intramuscular triacylglycerol (TG) synthesis was increased, while the rate of PA oxidation to CO2 and incorporation into mono- and diacylglycerols (MG/DG) and phospholipids (PL) remained unchanged. In rats with triiodothyronine (T3) excess the rate of all processes studied was enhanced, although the percentage incorporation of PA into different classes of intramuscular lipids was fairly constant and, independently of thyroid state and FA concentration in the medium, was 56–66% for TG, 9-14% for MG/DG and 24–32% for PL. Our results thus indicate that even short-term T3 excess accelerates the rate of FA uptake and metabolism in the oxidative soleus muscle, whereas in hypothyroid rats only intramuscular TG synthesis is affected. 相似文献
45.
Jang SH Seol JY Kim CH Yoo CG Kim YW Han SK Shim YS Lee CT 《International journal of molecular medicine》2004,13(1):181-186
TRAIL is a cytokine that can induce tumor-specific apoptosis through its specific death receptors (DR4 and DR5) and p53 has been proven to increase the expression of death receptors. To examine their interaction in tumor suppression, p53 and TRAIL genes were inserted in recombinant adenovirus vectors and transferred simultaneously into non-small cell lung cancer cell lines (NCI-H157, NCI-H358, NCI-H460 and A549). Western blot assay demonstrated production of TRAIL protein in NCI-H157 and A549 cell lines. Increased expressions of DR4 and DR5 of NCI-H157 and DR4 of A549 after p53 overexpression were confirmed by flow cytometry. p53 or TRAIL gene transfer increased sub-G1 fraction in cell cycle analysis and inhibited the tumor growth dose-dependently and the degree was potentiated by co-transfer. But isobologram analysis indicated an additive effect. Together, these data indicate that p53 and TRAIL interact additively on tumor apoptosis despite theoretical synergism. 相似文献
46.
Association of tumor necrosis factor and human leukocyte antigen DRB1 alleles with Graves' ophthalmopathy 总被引:4,自引:0,他引:4
Bednarczuk T Hiromatsu Y Seki N Płoski R Fukutani T Kuryłowicz A Jazdzewski K Chojnowski K Itoh K Nauman J 《Human immunology》2004,65(6):632-639
Tumor necrosis factor (TNF)-alpha plays a central role in the development of ophthalmopathy in patients with Graves' disease (GD). The aim of this study was to investigate the association of TNF promoter polymorphisms at positions -1031 (T-1031C), -863 (C-863A), -857 (C-857T), -308 (G-308A), and -238 (G-238A) with Graves' ophthalmopathy (GO). We studied the distribution of TNF and human leukocyte antigen (HLA) DRB1 alleles in 228 Polish white patients with GD, 106 of whom had ophthalmopathy (NOSPECS class > or = III) and 248 healthy subjects. TNF -308A and HLA-DRB1*03 alleles were significantly increased in patients with GD compared with healthy subjects. Stratification analysis revealed no independent association of -308A with GD when the DRB1*03 status was considered. Subdividing GD according to eye involvement revealed that the distribution of TNF promoter haplotypes differed significantly in patients with or without ophthalmopathy. The haplotype containing the -238A allele was absent in GO. The association of G-238A with GO was independent of DRB1 alleles. These results indicate that TNF G-308A is associated with susceptibility to GD (however, this association is not independent of HLA-DRB1*03) and that TNF G-238A is associated with the development of ophthalmopathy, suggesting that G-238A or a gene in linkage disequilibrium may be disease modifying in GD. 相似文献
47.
Kaliszan M Hauser R Kaliszan R Wiczling P Buczyñski J Penkowski M 《Experimental physiology》2005,90(5):727-738
The authors have conducted a systematic study in pigs to verify the models of post-mortem body temperature decrease currently employed in forensic medicine. Twenty-four hour automatic temperature recordings were performed in four body sites starting 1.25 h after pig killing in an industrial slaughterhouse under typical environmental conditions (19.5-22.5 degrees C). The animals had been randomly selected under a regular manufacturing process. The temperature decrease time plots drawn starting 75 min after death for the eyeball, the orbit soft tissues, the rectum and muscle tissue were found to fit the single-exponential thermodynamic model originally proposed by H. Rainy in 1868. In view of the actual intersubject variability, the addition of a second exponential term to the model was demonstrated to be statistically insignificant. Therefore, the two-exponential model for death time estimation frequently recommended in the forensic medicine literature, even if theoretically substantiated for individual test cases, provides no advantage as regards the reliability of estimation in an actual case. The improvement of the precision of time of death estimation by the reconstruction of an individual curve on the basis of two dead body temperature measurements taken 1 h apart or taken continuously for a longer time (about 4 h), has also been proved incorrect. It was demonstrated that the reported increase of precision of time of death estimation due to use of a multiexponential model, with individual exponential terms to account for the cooling rate of the specific body sites separately, is artifactual. The results of this study support the use of the eyeball and/or the orbit soft tissues as temperature measuring sites at times shortly after death. A single-exponential model applied to the eyeball cooling has been shown to provide a very precise estimation of the time of death up to approximately 13 h after death. For the period thereafter, a better estimation of the time of death is obtained from temperature data collected from the muscles or the rectum. 相似文献
48.
Maciej Bero Janusz Kasperczyk Grazyna Adamus 《Macromolecular chemistry and physics.》1993,194(3):907-912
High-molecular-weight copolymers of L ,L -lactide with ε-caprolactone were synthesized using initiators containing aluminium and zinc, i.e., AlEt2OEt, ZnEtOiPr, Al(acac)3 and AlEt3 + ZnEt2 + H2O. The chain microstructure was revealed to vary from random to diblock arrangement, depending on temperature and the kind of initiator used. In case of Al(acac)3 as initiator, the reactivity ratios of L ,L -lactide and ε-caprolactone were determined to be rL = 44 and rC = 0,28, respectively. 相似文献
49.
Opolski A Laskowska A Madej J Wietrzyk J Kłopocki A Radzikowski C Ugorski M 《Clinical & experimental metastasis》1998,16(8):673-681
Several lines of evidence indicate that sialosyl Le a , tumor-associated carbohydrate antigen present on human colon carcinoma cells, is involved in formation of metastases. To study the role of this carbohydrate structure in development of metastases, we have used the clone of human colon carcinoma CX-1 cells transfected with antisense expression vector containing fragment of cDNA for a1,3/4-fucosyltransferase (FT III), which is involved in synthesis of sialosyl Le a tetrasaccharide. It has been reported previously that, in contrast to the parental cells, the antisense-transfected CX-1.1AS5 cells do not express sialosyl Le a and do not adhere to E-selectin-expressing CHO cells. In the present work we have studied the formation of liver metastases by CX-1.1AS5 cells after their orthotopic or intrasplenic implantation into athymic nu/nu mice. After orthotopic implantation of sialosyl Le a -negative colon carcinoma CX-1.1AS5 cells, the number of mice with liver metas-tases was markedly lower (21% of mice) in comparison with their number after implantation of the parental CX-1.1 cells (86% of mice). However, no differences in ability to form colonies in liver were observed between parental CX-1.1 cells and antisense-transfected CX-1.1AS5 cells after intrasplenic inoculation. The liver metastases were formed in 89% and 84% of mice, respectively. Our data support the thesis on the importance of sialosyl Le a antigen expression in the development of liver metastases by colon cancer cells, and indicate the role of transplantation route and primary tumor localization in formation of metastases.© Kluwer Academic Publishers 1998 相似文献
50.
Mazur-Kolecka B Frackowiak J Le Vine H Haske T Evans L Sukontasup T Golabek A 《Neurobiology of aging》2003,24(2):355-364
Brain injury increases the risk of Alzheimer's disease (AD) through unknown mechanisms. We studied deposition of amyloid-beta protein (Abeta) in cells exposed to transforming growth factor beta1 (TGFbeta1), a cytokine that regulates cell metabolism during brain injury, and apolipoproteinE (apoE), the major lipid transporter in the brain. The studies were conducted by using brain vascular smooth muscle cells that are engaged in beta-amyloidosis in vivo and produce Abeta in cell culture. We found that cell treatment with TGFbeta1 together with apoE4 strongly increased the amount of cellular Abeta. The intracellular Abeta co-localized with apoE but not with TGFbeta, similarly as in vascular beta-amyloid. Some cellular Abeta/apoE deposits increased in size and persisted in culture even after the TGFbeta1 and apoE4 were removed. The appearance of cellular deposits of Abeta was associated with increased production of the amyloid-beta precursor protein and cellular retention of its mature form. The results suggest that the concomitant presence of apoE and TGFbeta1 can trigger vascular beta-amyloidosis by inducing intracellular formation of stable Abeta/apoE deposits. 相似文献