全文获取类型
收费全文 | 2529篇 |
免费 | 152篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 32篇 |
妇产科学 | 66篇 |
基础医学 | 384篇 |
口腔科学 | 56篇 |
临床医学 | 284篇 |
内科学 | 455篇 |
皮肤病学 | 35篇 |
神经病学 | 401篇 |
特种医学 | 92篇 |
外科学 | 380篇 |
综合类 | 7篇 |
一般理论 | 2篇 |
预防医学 | 154篇 |
眼科学 | 54篇 |
药学 | 174篇 |
肿瘤学 | 86篇 |
出版年
2023年 | 19篇 |
2022年 | 32篇 |
2021年 | 49篇 |
2020年 | 48篇 |
2019年 | 55篇 |
2018年 | 49篇 |
2017年 | 68篇 |
2016年 | 69篇 |
2015年 | 57篇 |
2014年 | 84篇 |
2013年 | 135篇 |
2012年 | 190篇 |
2011年 | 181篇 |
2010年 | 110篇 |
2009年 | 93篇 |
2008年 | 157篇 |
2007年 | 176篇 |
2006年 | 143篇 |
2005年 | 153篇 |
2004年 | 150篇 |
2003年 | 164篇 |
2002年 | 151篇 |
2001年 | 41篇 |
2000年 | 34篇 |
1999年 | 28篇 |
1998年 | 33篇 |
1997年 | 38篇 |
1996年 | 15篇 |
1995年 | 25篇 |
1994年 | 9篇 |
1993年 | 18篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有2692条查询结果,搜索用时 15 毫秒
21.
Juha P Ahtiainen Arto Pakarinen William J Kraemer Keijo H?kkinen 《Revue canadienne de physiologie appliquée》2004,29(5):527-543
The aim of the present study was to investigate acute hormonal and neuromuscular responses and recovery in strength athletes versus nonathletes during heavy resistance exercise performed with the forced and maximum repetitions training protocol. Eight male strength athletes (SA) with several years of continuous resistance training experience and 8 physically active but non-strength athletes (NA) volunteered as subjects. The experimental design comprised two loading sessions: maximum repetitions (MR) and forced repetitions (FR). MR included 12-RM squats for 4 sets with a 2-min recovery between sets. In FR the initial load was higher than in MR so that the subject could lift approximately 8 repetitions by himself and 4 additional repetitions with assistance. Before and after the loading protocols, blood samples were drawn to determine serum testosterone, free testosterone, cortisol and growth hormone concentrations, and blood lactate. Maximal voluntary isometric force and EMG activity of the leg extensors was measured before and after the loading as well as 24 and 48 hrs after the loading. The concentrations of the hormones measured increased significantly (p < .01-.001) after both loadings in both groups. The responses tended to be higher in FR than the MR loading and the increases of testosterone concentrations were significantly (p < .01) greater in both loadings in SA than in NA. Both loading protocols in both groups also led to neuromuscular fatigue observable with significant acute decreases in isometric strength by 32-52% (p < .001) and in maximal iEMG (p < .05-01) associated with large increases in blood lactate. These data suggest that, at least in experienced strength athletes, the forced-repetition protocol is a viable alternative to the more traditional maximum-repetition protocol and may even be a superior approach. 相似文献
22.
23.
Hans Juha Exner Eberhard Schlicker 《Naunyn-Schmiedeberg's archives of pharmacology》1995,351(1):46-52
Mouse or rat brain cortex slices were preincubated with 3H-noradrenaline and superfused with physiological salt solution containing desipramine. We studied the effects of prostaglandin E2 (PGE2), prostaglandin D2 (PGD2) and related drugs on the electrically evoked (50 mA, 2 ms, 0.3 Hz) tritium overflow.PGE2 inhibited the electrically evoked tritium overflow from mouse brain cortex slices; the maximum effect of PGE2 (79010) was attenuated by the 2-adrenoceptor agonist talipexole (to 52010) and enhanced by the 2-adrenoceptor antagonist rauwolscine (to 92%). Rauwolscine was added to the superfusion medium in all subsequent experiments. The effect of PGE2 was readily reversible upon withdrawal from the medium and remained constant upon prolonged exposure of the tissue to the prostanoid. Studies with EP receptor agonists, mimicking the inhibitory effect of PGE2, showed the following potencies (pIC50): sulprostone (8.22); misoprostol (8.00); PGE2 (7.74); PGEZ (7.61); iloprost (5.86). The concentration-response curve of PGE2 was marginally shifted to the right by the EP1 receptor antagonist AH 6809 (6-isopropoxy-9-oxoxanthene-2-carboxylic acid; apparent pA2 3.97) and by the TP receptor antagonist vapiprost (4.50). AH 6809, by itself, did not affect the evoked overflow whereas vapiprost increased it. PGD2 inhibited the evoked overflow at high concentrations (pIC50 4.90); this effect was not altered by the DP receptor antagonist BW A868C (3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexyl-2hydroxyethylamino)hydantoin), which, by itself, did not affect the evoked overflow. Indometacin slightly increased the evoked overflow and tended to increase the inhibitory effect of PGE2. PGE2 inhibited the electrically evoked tritium overflow also in rat brain cortex slices. The maximum effect (obtained in the presence of rauwolscine) was 61%; the pIC30 value was 7.67.The present study suggests that PGE2 inhibits noradrenaline release from mouse brain cortex via EP3 receptors and that its maximum effect is more marked in the mouse than in the rat. The inhibitory effect of PGD2 (in the mouse brain) does not involve DP receptors and may also be related to EP3 receptors. The EP3 receptors interact with a2-adrenoceptors and may be activated by endogenous prostanoids. 相似文献
24.
P. Hartikainen H. Soininen K. J. Reinikainen J. Sirviö R. Soikkeli P. J. Riekkinen 《Journal of neural transmission (Vienna, Austria : 1996)》1991,84(1-2):103-117
Summary We have investigated neurotransmitter-related markers of the cerebrospinal fluid (CSF) in a carefully screened series of normally aging subjects in standardized conditions in order to find out the influence of age and other confounding factors on CSF measures. The levels of 3-methoxy-4-hydroxyglycol (MHPG) and the activity of acetylcholinesterase (AChE) also increased with age, while homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5 HIAA) and immunoreactivities of somatostatin (SLI), beta-endorphin (BLI) and adrenocorticotropic hormone (ACTH) were unrelated to age. The gender of subjects had no significant effect on the levels of neurotransmitter markers, while seasonal changes, as well as height and weight of the subjects seemed to cause some variations in the levels of HVA, dopamine--hydroxylase (DBH) and ACTH. The study underscores the importance of standardized conditions and matched patient groups in the CSF studies. 相似文献
25.
Transient interference of right hemispheric function due to automatic emotional processing 总被引:4,自引:0,他引:4
We examined the effects of emotional stimuli on right and left hemisphere detection performance in a hemifield visual discrimination task. A group of 18 healthy subjects were asked to discriminate between upright and inverted triangles (target). Targets were randomly presented in the left or right visual hemifield (150 ms target duration). A brief emotional picture (pleasant or unpleasant; 150 ms stimulus duration) or neutral picture selected from the International Affective Picture System was randomly presented either in the same (47%) or the opposite (47%) spatial location to the subsequent target. Emotional or neutral stimuli offset 150 ms prior to the subsequent target. Subjects were instructed to ignore the pictures and respond to the targets as quickly and accurately as possible. Independent of field of presentation, emotional stimuli prolonged reaction times (P < 0.01) to LVF targets, with unpleasant stimuli showing a greater effect than pleasant stimuli. The current study shows that brief emotional stimuli selectively impair right hemispheric visual discrimination capacity. The findings suggest automatic processing of emotional stimuli captures right hemispheric processing resources and transiently interferes with other right hemispheric functions. 相似文献
26.
27.
Alcohol reduces prefrontal cortical excitability in humans: a combined TMS and EEG study. 总被引:3,自引:0,他引:3
Seppo K?hk?nen Juha Wilenius Vadim V Nikulin Marko Ollikainen Risto J Ilmoniemi 《Neuropsychopharmacology》2003,28(4):747-754
The effects of alcohol (0.8 g/kg) on the prefrontal cortex were studied in nine healthy subjects using the technique of transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG). A total of 120 magnetic pulses were delivered with a figure-of-eight coil to the left prefrontal cortex at the rate of 0.4-0.7 Hz. The EEG was recorded simultaneously with 60 scalp electrodes (41 electrodes were used for analysis); the TMS-evoked activation was estimated by the area under the global mean field amplitude (GMFA) time curve. TMS caused changes in EEG activity lasting up to 270 ms poststimulus. Alcohol decreased GMFA at 30-270 ms poststimulus (713+/-303 vs 478+/-142 microV ms; p=0.007). Alcohol-induced differences were most pronounced at anterior electrodes. These results suggest that alcohol reduces the excitability in the prefrontal cortex. 相似文献
28.
Juha Juntunen Juhani Huuskonen Krista Laine Riku Niemi Hannu Taipale Tapio Nevalainen David W Pate Tomi J?rvinen 《European journal of pharmaceutical sciences》2003,19(1):37-43
Phosphate esters of arachidonylethanolamide (AEA) and R-methanandamide were synthesized and evaluated as water-soluble prodrugs. Various physicochemical properties (pK(a), partition coefficient, aqueous solubility) were determined for the synthesized phosphate esters. The chemical stability of phosphate esters was determined at pH 7.4. In vitro enzymatic hydrolysis rates were determined in 10% liver homogenate, and in a pure enzyme-containing (alkaline phosphatase) solution at pH 7.4. The intraocular pressure (IOP) lowering properties of R-methanandamide phosphate ester were tested on normotensive rabbits. The phosphate promoiety increased the aqueous solubility of the parent compounds by more than 16500-fold at pH 7.4. Phosphate esters were stable in buffer solutions, but rapidly hydrolyzed to their parent compounds in alkaline phosphatase solution (t(1/2)<15 s) and liver homogenate (t(1/2)=8-9 min). The phosphate ester of R-methanandamide reduced IOP in rabbits. These results indicate that the phosphate esters of AEA and R-methanandamide are useful water-soluble prodrugs. 相似文献
29.
30.
Jouko Hartikainen Jukka Antila Matti Varpula Pauli Puukka Heikki Sepp Reidar Grnman 《The Laryngoscope》1998,108(12):1861-1866
Objectives and Study Design: The advent of the rigid endonasal endoscope and the development of functional endoscopic sinus surgery (FESS) technique have awakened interest in an endonasal endoscopic dacryocystorhinostomy (EESC-DCR) in treating nasolacrimal obstruction. This prospective, randomized study compares EESC-DCR with traditional external dacryocystorhinostomy (EXT-DCR) for their success rates, surgical duration, and postoperative symptoms. Patients and Methods: Sixty-four cases in 60 patients with primary acquired nasolacrimal sac or duct obstruction were divided into two subgroups by symptoms (simple epiphora/ chronic dacryocystitis). These patients were randomized within both subgroups into two operation groups. Altogether 32 EESC-DCRs and 32 EXT-DCRs were performed. The final follow-up visit was at 1 year. The patency of the lacrimal passage was investigated by irrigation and patients were questioned about their symptoms. Results: The success rate at 1 year after surgery was 75% for EESC-DCR and 91% for EXT-DCR after primary surgery. The difference was not statistically significant (P = .18). The success rate after secondary surgery with a follow-up time of 1 year was 97% in both study groups. The average duration for EESC-DCR was 38 minutes, and 78 minutes for EXT-DCR, (P < .001). Conclusions: EXT-DCR, when compared with EESC-DCR, appears to give a higher, although not statistically significant, primary success rate, but the secondary success rates are equal, indicating that these two different DCR techniques are acceptable alternatives. 相似文献