全文获取类型
收费全文 | 1170篇 |
免费 | 73篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 25篇 |
妇产科学 | 18篇 |
基础医学 | 257篇 |
口腔科学 | 16篇 |
临床医学 | 113篇 |
内科学 | 356篇 |
皮肤病学 | 20篇 |
神经病学 | 70篇 |
特种医学 | 17篇 |
外科学 | 122篇 |
综合类 | 5篇 |
预防医学 | 43篇 |
眼科学 | 5篇 |
药学 | 97篇 |
中国医学 | 3篇 |
肿瘤学 | 77篇 |
出版年
2023年 | 5篇 |
2022年 | 33篇 |
2021年 | 34篇 |
2020年 | 24篇 |
2019年 | 21篇 |
2018年 | 28篇 |
2017年 | 20篇 |
2016年 | 25篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 56篇 |
2012年 | 84篇 |
2011年 | 97篇 |
2010年 | 66篇 |
2009年 | 48篇 |
2008年 | 75篇 |
2007年 | 96篇 |
2006年 | 83篇 |
2005年 | 67篇 |
2004年 | 72篇 |
2003年 | 59篇 |
2002年 | 60篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有1251条查询结果,搜索用时 265 毫秒
1.
2.
Jan Jozef Braszko Anna Walesiuk Przemyslaw Wielgat 《Journal of the renin-angiotensin-aldosterone system》2006,7(3):168-174
This study tests the hypothesis that the facilitation of learning and improvement of memory observed after an intracerebroventricular (i.c.v.) injection of angiotensin II (Ang II) is, in fact, caused by its derivative angiotensin IV (Ang IV). We ran two memory tests as well as an auxiliary test assessing motor performance in rats injected (i.c.v., 1 nmol in 2 microl saline) with Ang II or Ang IV. There were separate groups receiving peptide or saline five, 10 and 15 minutes before testing. Ang IV significantly increased step-through latencies in a passive avoidance paradigm as well as improved discrimination between familiar and unfamiliar objects in an object recognition test in all groups showing better retrieval of memory of aversive as well as appetitive stimuli in the peptide-treated groups regardless of the time of its injection. In contrast, rats treated with Ang II demonstrated significant improvement of memory of aversive and appetitive stimuli in the same tests only 15 minutes after its i.c.v. injection, with no effect in the groups injected five minutes before testing and slight efficacy in those injected 10 minutes before the test. Numbers of crossings, rearings and bar approaches in an open field were similar both in the peptide-treated and control groups making it unlikely that changes in motor performance affected the memory tests. In line with the present views on the intracellular metabolism of Ang II, these results suggest degradation to Ang IV by aminopeptidases A and N is necessary before the cognitive effects can occur. 相似文献
3.
Grzegorz Oracz Bozena Cukrowska Beata Oralewska Jozef Ryzko Jerzy Socha 《Clinical gastroenterology and hepatology》2006,4(6):802; author reply 802-802; author reply 803
4.
Waclaw Weyde Roman Badowski Magdalena Krajewska Jozef Penar Krzysztof Moron Marian Klinger 《Nephrology, dialysis, transplantation》2004,19(6):1618-1621
BACKGROUND/AIMS: Catheterization of the femoral vein is a safe and recommended method of temporary access for haemodialysis. In some patients, however, because of the lack of other possibilities, it is necessary to maintain long-term femoral cannulation. The aim of the study was to evaluate the frequency of stenosis after prolonged femoral cannulation. METHODS: The 24 patients incorporated in the study were divided into two groups. Group 1 consisted of 10 end-stage kidney failure patients (four females and six males, aged 32-75 years, average 55.6+/-13.6 years) in whom femoral catheters were maintained for less than 2 weeks (5-14 days, average 9.3+/-3.6 days). Group 2 included 14 chronic haemodialysis patients (six females and eight males aged 23-65 years, average 49.5+/-13.27 years). The time of catheter maintenance ranged from 2 to 16 weeks (average 6.4+/-4.2 weeks). Femoral and iliac vein status was evaluated using magnetic resonance imaging. RESULTS: A feature of venous stenosis of both the femoral and iliac veins was disclosed in four patients in whom femoral cannulation lasted more than 4 weeks. There were no stenoses in group 1. CONCLUSION: Long-term femoral cannulation for more than 4 weeks may be associated with a significant risk of stenosis in the femoral and/or external iliac veins. 相似文献
5.
6.
Differential effects of estradiol, raloxifene and tamoxifen on estrogen receptor expression in cultured human skin fibroblasts 总被引:2,自引:0,他引:2
7.
Van Reenen CG O'Connell NE Van der Werf JT Korte SM Hopster H Jones RB Blokhuis HJ 《Physiology & behavior》2005,85(5):557-570
The present study examined the consistency over time of individual differences in behavioral and physiological responsiveness of calves to intuitively alarming test situations as well as the relationships between behavioral and physiological measures. Twenty Holstein Friesian heifer calves were individually subjected to the same series of two behavioral and two hypothalamo-pituitary-adrenocortical (HPA) axis reactivity tests at 3, 13 and 26 weeks of age. Novel environment (open field, OF) and novel object (NO) tests involved measurement of behavioral, plasma cortisol and heart rate responses. Plasma ACTH and/or cortisol response profiles were determined after administration of exogenous CRH and ACTH, respectively, in the HPA axis reactivity tests. Principal component analysis (PCA) was used to condense correlated measures within ages into principal components reflecting independent dimensions underlying the calves' reactivity. Cortisol responses to the OF and NO tests were positively associated with the latency to contact and negatively related to the time spent in contact with the NO. Individual differences in scores of a principal component summarizing this pattern of inter-correlations, as well as differences in separate measures of adrenocortical and behavioral reactivity in the OF and NO tests proved highly consistent over time. The cardiac response to confinement in a start box prior to the OF test was positively associated with the cortisol responses to the OF and NO tests at 26 weeks of age. HPA axis reactivity to ACTH or CRH was unrelated to adrenocortical and behavioral responses to novelty. These findings strongly suggest that the responsiveness of calves was mediated by stable individual characteristics. Correlated adrenocortical and behavioral responses to novelty may reflect underlying fearfulness, defining the individual's susceptibility to the elicitation of fear. Other independent characteristics mediating reactivity may include activity or coping style (related to locomotion) and underlying sociality (associated with vocalization). 相似文献
8.
9.
Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride was studied. The conversion curves could be linearized by the first order equation and the experimental rate constants kexp for the initiation by various ammonium salts were determined. The rate of copolymerization was found to depend on the size of the cation but not on the type of anion. kexp is a function of the first power initiator concentration but is independent of epoxide and anhydride concentration. The activation energy for the cetyltrimethylammonium bromide (CAB) initiated copolymerization in nitrobenzene was determined to be 73,5 kJ/mol. The kinetic scheme of copolymerization, which agrees well with the experimental results, was solved. The rate constant of the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride catalyzed by CAB in nitrobenzene was found to be 2,76·10?2l.mol?1·s?1. The ratio of rate constants for both propagation steps, i.e. reaction of carboxylate anion with epoxide (k3) and reaction of alkoxide anion with anhydride (k2), was determined to be k3/k2 = 0,2 ± 0,1. 相似文献
10.
Hennig Ewa E.; Demkowicz-Dobrzanski Krzysztof K.; Sawicki Jozef T.; Mojska Hanna; Kujawa Marek 《Carcinogenesis》1983,4(10):1243-1246
The effect of butylated hydroxyanisole (BHA) administrationon the hepatic monooxygenase system of nuclear and microsomalfraction was investigated in male mice. Addition of BHA to thediet significantly lowered the content of cytochrome P-450 inliver nuclei and increased the specific activity of NADPH-cytochromec reductase and the content of cytochrome b5 in liver microsomes.Incubation of benzo[a]pyrene (BP) with liver nuclei from BHA-fedmice resulted in inhibition of binding of BP metabolites tonuclear macromolecules by 50% compared with control. However,there was no effect of BHA on the binding of BP metabolitesto macromolecules when BP was incubated with added DNA and livermicrosomes from BHA-fed mice. It has been postulated that modificationof nuclear monooxygenases by BHA may play a role in the inhibitoryeffect of BHA on BP carcinogenesis. 相似文献