首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   24197篇
  免费   1061篇
  国内免费   211篇
耳鼻咽喉   387篇
儿科学   351篇
妇产科学   304篇
基础医学   3970篇
口腔科学   402篇
临床医学   1963篇
内科学   4632篇
皮肤病学   781篇
神经病学   1974篇
特种医学   1286篇
外科学   3188篇
综合类   345篇
一般理论   4篇
预防医学   885篇
眼科学   500篇
药学   2148篇
  15篇
中国医学   296篇
肿瘤学   2038篇
  2024年   71篇
  2023年   245篇
  2022年   518篇
  2021年   863篇
  2020年   486篇
  2019年   644篇
  2018年   698篇
  2017年   535篇
  2016年   798篇
  2015年   1036篇
  2014年   1164篇
  2013年   1386篇
  2012年   2044篇
  2011年   1954篇
  2010年   1163篇
  2009年   953篇
  2008年   1441篇
  2007年   1342篇
  2006年   1268篇
  2005年   1134篇
  2004年   1005篇
  2003年   848篇
  2002年   748篇
  2001年   443篇
  2000年   420篇
  1999年   363篇
  1998年   195篇
  1997年   169篇
  1996年   163篇
  1995年   129篇
  1994年   106篇
  1993年   74篇
  1992年   108篇
  1991年   104篇
  1990年   85篇
  1989年   80篇
  1988年   89篇
  1987年   75篇
  1986年   61篇
  1985年   59篇
  1984年   47篇
  1983年   45篇
  1982年   33篇
  1981年   25篇
  1980年   28篇
  1979年   38篇
  1978年   22篇
  1977年   19篇
  1976年   18篇
  1975年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
We examined the efficacy of two new preservation solutions containing trehalose-an extracellular type (ET-K) of solution and an intracellular type (IT-K) of solution — in relation to that of Euro-Collins (EC) solution in 20-h canine lung preservation. Canine lungs were flushed with one of the three solutions (n=5 for each solution) after pretreatment with PGE1 (20 g/kg) and were stored for 20 h at 4°C. The left lungs were transplanted and evaluated to 6 h post transplant. In the ET-K group, the arterial oxygen tension after reperfusion was significantly higher than in the IT-K and EC groups. The pulmonary vascular resistance, wet/dry weight ratio, and histological evaluation of each transplanted lung in the ET-K group were also better than in the IT-K and EC groups. This indicates that ET-K solution is useful for 20-h preservation of canine lung grafts.  相似文献   
92.
The effect of vagotomy on the post-prandial alkaline tide was assessed by measuring the fasting and postprandial urinary pH before and after vagotomy in 50 cases of chronic duodenal ulcer treated by posterior truncal vagotomy or gastrojejunostomy or pyloroplasty. Results showed that post-prandial urinary pH fell after vagotomy confirming the completeness of vagotomy. This test is safe, reliable, noninvasive and a simpler bedside procedure as compared to the conventional Hollander''s insulin test.KEY WORDS: Vagotomy, Alkaline tide  相似文献   
93.
Long-term outcome in 134 patients with galactosaemia   总被引:6,自引:0,他引:6  
In a retrospective study 134 galactosaemic patients, born between 1955 and 1989 in the Federal Republic of Germany were traced and their long-term outcome evaluated. We investigated 83 galactosaemic patients (78 homozygotes, 5 compound heterozygotes) by clinical, psychometric and laboratory testing; 31 patients were evaluated by medical history, the remaining 20 patients had died due to sequelae of the underlying disease. In 48 out of 78 classical galactosaemia patients galactose-free therapy had been started before the 15th day, in 19 between days 15 and 56 and in 11 patients after the 56th day. Physical findings revealed that puberty was delayed in 1 out of 18 males and 6 out of 11 females. Neurological abnormalities included ataxia (n=6), intention tremor (n=11) and microcephaly (n=10). Speech abnormalities were found in 43 out of 66 patients over 3 years of age and disturbance of visual perception and/or arithmetic deficits in 29. Intelligence declined with age, i.e., a DQ or IQ less than 85 was found in 4 out of 34 patients less than 6 years of age (12%), in 10 out of 18 between 7 and 12 years (56%) and in 20 out of 24 older than 12 years (83%). Metabolite patterns (RBC galactose-1-phosphate and UDP-galactose, plasma and urinary galactitol) did not correlate with DQ or IQ. Dietary compliance was good in almost all patients. Compound heterozygotes (n=5) had normal mental and growth development and all laboratory parameters were in the normal range. The cause of the unsatisfactory outcome of well-treated galactosaemic patients with disturbances in long-term development remains unclear. This could be due to a chronic intoxication of galactose metabolites or a deficiency of UDP-galactose or galactose-containing glycoproteins or glycolipids.This study was supported by a grant from the Stifterverband für die Deutsche Wissenschaft (Huebner-stiftung), grant TS 114/18/89 and by the Arbeitsgemeinschaft für Pädiatrische Stoffwechselstörungen  相似文献   
94.
Analysis of particle size distribution of a sample of fine aluminum hydroxide powder was carried out by four different methods,i. e., conductivity, air permeability, gas-adsorption and sedimentation. Each method was reproducible. The results obtained by Coulter counter and sedimentation balance were similar, and the data obtained by Lea and Nurse permeameter and Stroehlein areameter were also similar. But the results differ considerably between the former and the latter. The advantages and disavantages of each method were discussed briefly and a means of comparing the results with those obtained by surface area measurements was shown.  相似文献   
95.
Corneal permeability of variousn-alkylp-hydroxybenzoates (parabens) was studiedin vitro using excised rabbit corneas, and the effect of lipophilicity of parabens on the corneal permeability was also investigated. Permeability coefficients were obtained from the least-square linear regression after the steady state had been reached. Lipophilicity of parabens was calculated by distribution coefficients determined in octanol-S \(12_\phi [\kern-0.15em[ \) rensen’s buffer solution (pH 5.0). The relationship between lipophilicity and corneal permeability of parabens was not linear, but the optimum lipophilicity for the maximum permeation was found. The influence of tween 80 on corneal permeability of methyl and butylparaben was not significant.  相似文献   
96.
We programmed a formula which predicts the incidence of either myocardial infarction or cardiac death during the postoperative period. The original formula was proposed by Shah et al, based on their own data and analysis. The program is simple and is written in a language called Quick Basic. The use of this program is also simple. Such a program has improved the use of this analysis substantially. The program has been posted on to a few Computer network services as a free software.(Suwa K, Ogura S: Programming a predictive formula for angina and other risk factors in patients with cardiac diseases undergoing non-cardiac operations. J Anesth 6: 241–242, 1992)  相似文献   
97.
One patient with osteosarcoma and one with Ewing’s sarcoma of the femur were in 1987 and 1988 treated with prosthetic replacement of the femur and chemotherapy. There has been no loosening of the prostheses and no recurrence of the tumor. The patients have maintained 60% and 63% limb function scores evaluated by ISOLS criteria.
Résumé  Deux patients, l’un avec un ostéosarcome, l’autre avec un sarcome d’EWING, furent opérés en 1987–1988 avec remplacement prothétique du fémur, associéà une chimiothérapie. Ces patients ont été suivis sans qu’il soit noté de récidive. Il n’y a pas de descellement, ni de luxation de la prothèse. Un score fonctionnel évalué selon les critères de l’ISOLS, montre une conservation de 60% et 63% de la fonction du membre inférieur.


Accepted: 17 March 2000  相似文献   
98.
99.
100.
Vitamin H (biotin) was incorporated into a hydrophobically modified polysaccharide, pullulan acetate (PA), in order to improve the cancer-targeting activity and internalization of self-assembled nanoparticles. The biotinylated pullulan acetate (BPA) nanoparticles were prepared by a diafiltration method and the mean diameter was approximately 100 nm. Three samples of biotinylated pullulan acetate (BPA), comprising 7 (BPA 1), 20 (BPA 2), and 39 (BPA 3) vitamin H groups per 100 anhydroglucose units of PA, were synthesized. The critical aggregation concentrations (CAC) of the BPA nanoparticles in distilled water were 3.1 x 10(-3), 4.3 x 10(-3) and 6.8 x 10(-3) mg/ml for BPA 1, BPA 2, and BPA 3, respectively. Adriamycin (ADR) was loaded into the BPA nanoparticles as a model drug. The loading efficiencies and ADR content in the BPA nanoparticles decreased with increasing vitamin H content due to a lower hydrophobicity. The RITC-labeled BPA nanoparticles exhibited very strong adsorption to the HepG2 cells, while the RITC-labeled PA nanoparticles did not show any significant interaction. The degree of the interaction increased with increasing vitamin H content. Confocal laser microscopy also revealed that internalization of the BPA nanoparticles into the cancer cells depended on the vitamin H content.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号