全文获取类型
收费全文 | 1507篇 |
免费 | 121篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 50篇 |
妇产科学 | 37篇 |
基础医学 | 274篇 |
口腔科学 | 12篇 |
临床医学 | 104篇 |
内科学 | 318篇 |
皮肤病学 | 17篇 |
神经病学 | 122篇 |
特种医学 | 39篇 |
外国民族医学 | 1篇 |
外科学 | 90篇 |
综合类 | 99篇 |
预防医学 | 118篇 |
眼科学 | 7篇 |
药学 | 219篇 |
1篇 | |
中国医学 | 20篇 |
肿瘤学 | 118篇 |
出版年
2024年 | 3篇 |
2023年 | 35篇 |
2022年 | 47篇 |
2021年 | 89篇 |
2020年 | 56篇 |
2019年 | 76篇 |
2018年 | 80篇 |
2017年 | 61篇 |
2016年 | 58篇 |
2015年 | 76篇 |
2014年 | 97篇 |
2013年 | 142篇 |
2012年 | 97篇 |
2011年 | 89篇 |
2010年 | 77篇 |
2009年 | 68篇 |
2008年 | 68篇 |
2007年 | 79篇 |
2006年 | 40篇 |
2005年 | 41篇 |
2004年 | 26篇 |
2003年 | 42篇 |
2002年 | 26篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 20篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有1658条查询结果,搜索用时 0 毫秒
1.
2.
失眠症患者睡眠质量的主观评估与多导睡眠图参数对比分析 总被引:3,自引:0,他引:3
目的 探讨失眠症患者对睡眠质量的主观评估,并通过对多导睡眠图(PSG)睡眠参数的定量分析,对失眠症患者的睡眠状况进行客观评估,进一步将二者进行对比分析.方法 对失眠症患者和健康人各100例运用匹兹堡睡眠质量指数问卷(PSQI)进行评定,并分别进行多导睡眠图的整夜睡眠描记,次日晨起后询问夜间睡眠情况.结果 失眠症组PSQI各成分得分及总分均高于对照组,差异有统计学意义(P<0.01).与对照组相比,失眠症组的睡眠潜伏期(min)延长(失眠症组43.69±11.54,对照组16.01±10.44)、总睡眠时间(min)减少(失眠症组314.65±91.89,对照组446.41±77.81)、睡眠效率降低(失眠症组64.51%±18.59%,对照组91.32%±3.58%)、快眼动睡眠时间(min)减少(失眠症组33.26±15.61,对照组93.21±21.63),差异有统计学意义(P<0.01).失眠症组对总睡眠时间的评估较PSG检测值显著减低、对睡眠潜伏期的评估较PSG检测值显著增高,自我评估与实际睡眠情况不一致.结论 失眠症患者睡眠质量较差.失眠症患者的PSG各睡眠参数有特征性的改变,利用PSG检查发现失眠症患者对失眠情况的主客观评估不一致,存在过高估价睡眠潜伏期和过低估价睡眠时间的倾向. 相似文献
3.
Leopold Rosenmayr 《Journal of cross-cultural gerontology》1988,3(1):21-40
This paper presents and interprets empirical findings from field studies in a Bambara village in the Republic of Mali in order to place the traditional position of the elderly in cultural context. The significance of a seniority principle underlying the social structure of African society is emphasized. Thus attitude and behavioral changes which affect the status of the elderly have wider ramifications for the society as a whole. Attention centers on the role of age sets, myth and ritual, ancestor worship and socialization practices as elements of a total cultural system in which the rules of seniority provide an organizing force. In the last section, the ways in which social change threatens the viability of a social system governed by the seniority principle are reviewed. Signs of breaks in the solidarity of the traditional community are noted. Finally, two strategies for improving the position of the elderly in the African countryside as the traditional system disintegrates are proposed.To the people of Sonongo in gratitude. 相似文献
4.
Scott R. Dyer John A. Sorensen Lippo V.J. Lassila Pekka K. Vallittu 《Dental materials》2005,21(12):1104-1110
OBJECTIVES: Damage mechanics has been defined as the study of the initiation (initial failure) and accumulation of damage to and including rupture (final failure). This study was designed to evaluate the effect of increasing fiber-reinforced composite (FRC) substructure within a standardized fixed partial denture (FPD) model on the failure performance, in terms of damage mechanics. METHODS: The two FRC restorative systems, Targis/Vectris (TV) (Ivoclar Vivadent) and EverStick (ES) (Stick Tech with Gradia, GC Corp.), were used to restore the molar FPD model (1.5 mm axial and 2.0 mm occlusal reduction). Templates were used to standardize substructure designs with 0, 18, 43, and 66% cross-sectional FRC volume fraction (V(FRC)) of fiber substructure. Specimens (n = 5) were homogenized at 29 points and stored for 1 week at 37 degrees C in distilled water. Specimens were luted with calcium hydroxide, then statically loaded until failure. Initial failure (IF), final failure (FF) and the mode of failure were recorded. RESULTS: The lowest mean load to initial failure was 530 N (TV 18%) and the highest was 1208 N (ES 66%). Linear regression analysis calculated the Pearson's correlation coefficient (r) for the interactions between V(FRC) and IF (ES: r = 0.7879, TV: r = 0.6184), V(FRC) and FF (ES: r = 0.912, TV: r = 0.8152), and between IF and FF (ES: r = 0.892, TV: r = 0.7237). Unreinforced specimens universally fractured instantaneously. SIGNIFICANCE: The highest loads to initial and final failure were yielded by specimens with the highest cross-sectional V(FRC). 相似文献
5.
Human oocytes isolated from healthy non-preovulatory antralfollicles which had not been stimulated spontaneously resumedmeiosis at a low rate (31%) when compared with those from atreticfollicles (73%). Human follicular fluid did not inhibit spontaneousmaturation of rat oocytes in vitro, regardless of the qualityor maturity of the follicle or the treatment of the patient.In the human, oocyte maturation may involve a stimulatory processas well as a removal of inhibition. 相似文献
6.
Fukushi Shuetsu Okada Masato Kageyama Tsutomu Hoshino Fuminori B. Katayama Kazuhiko 《Virus genes》1999,19(2):153-161
Translation initiation of hepatitis C virus (HCV) RNA is controlled by an internal ribosome entry site (IRES) contained in 5 noncoding region (NCR) and in several nucleotides of the coding region. The ability of a 25-kilodalton cellular protein (p25) to bind the HCV 5 NCR is correlated with the efficiency of translation initiation of HCV RNA, indicating that this protein plays a critical role in HCV translation (S. Fukushi, C. Kurihara, N. Ishiyama, F. B. Hoshino, A. Oya, and K. Katayama, J Virol 71, 1662–1666, 1997). We have extended the study for identification of the IRES region required for p25 binding. For this purpose, we have performed UV cross-linking competition analyses using 5- or 3- deleted mutants of the HCV 5 NCR as competitor RNAs for binding of p25 to wild-type HCV 5 NCR. Competitor RNAs lacking nucleotides (nt) 47–74 or nt 279–331 did not inhibit p25 binding to the HCV IRES, indicating that these regions are necessary for interaction of the p25 and HCV IRES. Since p25 binding was not observed in the IRES elements of encephalomyocarditis virus and poliovirus in UV cross-linking competition analyses, the p25 binding may be specific for the HCV IRES. p25 bound to the HCV IRES was detected when a purified 40S ribosomal subunit was used for UV cross-linking experiment, indicating that p25 is one of 40S ribosomal subunit proteins. These results reveal an unique interaction between the 40S ribosomal subunit and HCV IRES to contribute to translation initiation of the HCV genome. 相似文献
7.
8.
J. F. Dormont D. Farin A. Schmied M. Amalric 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1989,77(2):271-282
Summary The activity of 98 Red Nucleus neurons was recorded in 3 cats operantly conditioned to perform a ballistic forelimb flexion movement triggered after a brief sound in a simple Reaction Time condition, or Delayed after the same sound in the presence of a tone cue. Fifty-eight task related neurons presented changes of activity in either one or both conditions. Forty-four of them were studied quantitatively and classified in 3 categories: 1) only 16% of the units presented similar changes of firing preceding the triggered or delayed movement; 2) most units (55%) presented different changes of activity in the two conditions: in the Delayed condition, the activation occurred earlier before the movement, and/or the change in magnitude was reduced or the pattern of activity was modified; 3) moreover, for 29% of the units, the change of activity observed before movement in the Reaction Time condition was severely reduced or even absent in the Delayed condition. For some of these neurons a building-up of activity was observed very early in the Reaction Time condition, during the preparatory period, well before the occurrence of the conditioned stimulus. These results show that the Red Nucleus activity preceding a movement is clearly dependent on its initiation conditions. The distinct patterns of unit firing observed in the Reaction Time condition and in the Delayed condition are tentatively related to the different preparation and initiation constraints determined by the behavioral conditions. 相似文献
9.
10.
A. Hayashi Y. Kagamihara Y. Nakajima H. Narabayashi Y. Okuma R. Tanaka 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1988,70(2):437-440
Summary Reciprocal innervation of the soleus motoneurones upon initiation of voluntary ankle dorsiflexion was investigated in eight patients with Parkinson's disease. H-reflex and visually guided step tracking methods were used for testing moto-neurone excitability and for controlling the timing of movement initiation, respectively. While reciprocal inhibition appeared almost simultaneously with the agonist electromyographic (EMG) onset in normal subjects (Kagamihara and Tanaka 1985), facilitation appeared in the majority of patients under the same onset condition. It increased slowly, reaching a maximum at about 100 ms after the EMG onset. It then subsided slowly at around 200–300 ms, and was replaced thereafter by an inhibitory effect. No coactivation of the soleus muscle was detected electromyographically. The facilitation between the EMG onset and the onset of mechanical contraction was attributed to the direct effect of the descending command from the brain, suggesting a certain disorder in controlling the system for reciprocal innervation. 相似文献