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   13231篇
  免费   1137篇
  国内免费   76篇
耳鼻咽喉   152篇
儿科学   369篇
妇产科学   321篇
基础医学   1652篇
口腔科学   290篇
临床医学   1597篇
内科学   2571篇
皮肤病学   197篇
神经病学   971篇
特种医学   1035篇
外国民族医学   2篇
外科学   1594篇
综合类   396篇
一般理论   8篇
预防医学   1405篇
眼科学   174篇
药学   853篇
中国医学   9篇
肿瘤学   848篇
  2021年   172篇
  2020年   127篇
  2019年   195篇
  2018年   224篇
  2017年   161篇
  2016年   155篇
  2015年   181篇
  2014年   313篇
  2013年   450篇
  2012年   580篇
  2011年   609篇
  2010年   339篇
  2009年   327篇
  2008年   478篇
  2007年   600篇
  2006年   538篇
  2005年   543篇
  2004年   477篇
  2003年   466篇
  2002年   460篇
  2001年   434篇
  2000年   413篇
  1999年   346篇
  1998年   206篇
  1997年   182篇
  1996年   209篇
  1995年   196篇
  1994年   157篇
  1993年   155篇
  1992年   329篇
  1991年   282篇
  1990年   284篇
  1989年   310篇
  1988年   243篇
  1987年   232篇
  1986年   247篇
  1985年   254篇
  1984年   171篇
  1983年   142篇
  1982年   120篇
  1981年   103篇
  1979年   205篇
  1978年   161篇
  1977年   115篇
  1976年   99篇
  1975年   105篇
  1974年   135篇
  1973年   110篇
  1971年   95篇
  1970年   100篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Genetics can pose special challenges to the principle of confidentiality within the health professional-patient relationship, since genetic information is by its nature both individual and familial. Most professional guidelines allow confidentiality to be broken in rare circumstances, where it will prevent a 'serious', 'imminent' and 'likely' harm. We argue that the types of harms that may result from genetic medicine are particularly diverse. Using clinical examples, we explore ethical issues that arise when balancing individual and family member interests. As genetic testing becomes more, widespread situations will arise where clinicians are faced with a choice between preserving the confidentiality of one patient and preventing harm to another. Professionals need to incorporate the notion of familial implications in their counseling of individuals. Since such dilemmas have been relatively rare in the pre-genetic age, we call for a wider debate on the balance between confidentiality and harm to others.  相似文献   
132.
The present study showed that incorporation of CpG adjuvant into plasmid DNA coding for NcGRA7 antigen resulted in a twofold increase in the level of protection against congenital transfer of Neospora caninum. The level of protection was considerably higher than that observed in pups born from dams immunized with nonrecombinant plasmid.  相似文献   
133.
Summary The artery of the sino-atrial node was studied in 100 normal human hearts after injection of each coronary artery with coloured gelatine containing a radiopaque substance. The hearts belonged to 69 males and 31 females, being 64 Caucasians and 36 non-Caucasians (Negroes and Mulattoes) whose age ranged from 7 to 80 years. Since the individuals had committed suicide or were victims of accidents, their hearts, after pathologists' evaluation, were considered normal. The sinoatrial node of the normal human heart is supplied by the right coronary artery more frequently (58%±4.9% of the cases) than by the left (42%±4.9). The right anterior medial atrial artery, originating from the right coronary at the level of the medial third of the right anterior quadrant of the atrial dome, is most frequently (50%±5) responsible for the blood supply of the sinoatrial node. Among the branches of the left coronary artery, the left anterior medial atrial artery, originating at the level of the medial third of the left. anterior quadrant of the atrial cupola, was the most frequent blood supplier (25%±4.3) of the sinoatrial node. The origin of the artery of the sinoatrial node from the proximal portion or trunk of the left coronary artery was less frequent (12%±3.2) than the origin from the circumflex artery (30%±4.5). Neither sex nor race influenced the variations of the origin of the sino-atrial node.
Variations d'origine de l'artère du noeud sinu-atrial du coeur humain normal
Résumé L'a. du noeud sinu-atrial a été étudiée sur 100 coeurs humains normaux après injection de chaque a. coronaire à la gélatine colorée additionnée d'une substance radio-opaque. Les coeurs provenaient de 69 hommes et 31 femmes, 64 caucasiens et 36 non caucasiens (nègres et mulâtres) âgés de 7 à 80 ans. Ces sujets étant décédés par suicide ou des suites d'accidents, leurs coeurs ont été considérés comme normaux après examen anatomo-pathologique. Le noeud sinu-atrial du coeur humain est vascularisé par l'a. coronaire droite plus fréquemment (58 %±4,9) que par l'a. coronaire gauche (42 %±4). L'a. atriale antéro-médiale droite, issue de l'a. coronaire droite au niveau du tiers médial du quadrant antérieur droit du dôme atrial est l'artère la plus fréquemment en cause (50 %±5) dans la vascularisation du noeud sinuatrial. Parmi les branches de l'a. coronaire gauche, l'a. atriale antéro-médiale gauche, née au niveau du tiers médial du quadrant antérieur gauche du dôme atrial, était la branche la plus fréquemment en cause (25 %±4,3) dans la vascularisation du noeud sinu-atrial. La naissance de l'a. du noeud sinu-atrial à partir de la partie proximale ou du tronc de l'a. coronaire gauche était moins fréquente (12 %±3,2) que son origine à partir du rameau circonflexe (30 %±4,5). Les variations d'origine de l'a. du noeud sinu-atrial n'apparaissaient pas influencées par le sexe ou la race.
  相似文献   
134.
Marked abnormalities in cardiovascular function accompany septic shock, and bacterial endotoxin is believed to be one of the principal mediators of these abnormalities. To evaluate the cardiovascular effects of endotoxemia in humans, we measured hemodynamic variables in nine normal subjects given an intravenous bolus dose of endotoxin (Escherichia coli, 4 ng per kilogram of body weight) and in six normal subjects given a bolus dose of saline, before and three hours after administration. All the subjects then underwent volume loading with normal saline (mean, 2217 ml) during the fourth and fifth hours after administration of the bolus, and the measurements were repeated. Three hours after the administration of endotoxin and before volume loading, the cardiac index had increased by 53 percent and the heart rate by 36 percent (both changes were significant; P less than or equal to 0.008), and the systemic vascular-resistance index had decreased by 46 percent (P = 0.004). After volume loading (five hours after the administration of endotoxin), the left ventricular ejection fraction decreased by 1 percent of the base-line value in the subjects given endotoxin, but increased by 14 percent in the controls (P = 0.008). The left ventricular end-diastolic and end-systolic volume indexes increased by 18 percent (P = 0.07) and 24 percent (P = 0.042), respectively. Left ventricular performance, as measured by the ratio of the peak systolic pressure to the end-systolic volume index, was depressed (a decrease of 0.90 in the subjects given endotoxin vs. an increase of 0.76 in the controls; P = 0.024). We conclude that the administration of endotoxin to normal subjects causes a depression of left ventricular function that is independent of changes in left ventricular volume or vascular resistance. The changes in function are similar to those observed in septic shock and suggest that endotoxin is a major mediator of the cardiovascular dysfunction in this condition.  相似文献   
135.
Denture soft lining materials are compliant cushions used at the oral tissue-denture interface. They are generally required to have sufficient compliance to redistribute mastication load, as well as an adequate modulus for long-term dimensional stability and control over the water uptake. This study investigated the effect of using silane treated fumed silica as a filler on the properties of experimental soft lining materials based on blends of isoprene-styrene (SIS) block co-polymer and mixtures of methyl methacrylate (MMA) and 1,6-hexandiol dimethacrylate (HDMA). The overall elastomer/monomer ratios were maintained, whereas the monomers ranged from 10 to 60% HDMA. The silica filler level was maintained at 10 wt% with respect to SIS. The properties investigated were the dynamic mechanical parameters of storage modulus (E') and tan delta as a function of temperature and the quasi-static mechanical parameters of ultimate tensile strength (UTS) and elongation to break (Eb) as well as absorption properties that were carried out in water and saline. In both unfilled and filled systems there was an increase in E' and a decrease in tan delta with an increase in HDMA. Silica addition tended to increase E' and substantially reduce tan delta in materials with less than 20% HDMA. UTS decreased with filler and HDMA content, however, Eb was greater for filled systems. Generally, in the long term, the water uptake decreased with increasing HDMA content and E'. The silanated silica further reduced the water uptake, indicating a cross-linking effect, thus increasing the restraining force on droplet growth. The uptake in saline was significantly reduced indicating an osmotically controlled uptake process.  相似文献   
136.
Problems with measuring alexithymia   总被引:1,自引:0,他引:1  
Research evaluating the relationship of alexithymia to medical and psychiatric disorders has been compromised by the poor psychometric properties of the instruments that have been used to measure alexithymia. This study evaluated the psychometric properties of a recently introduced measure of alexithymia--the revised Schalling-Sifneos Personality Scale (SSPS-R). While the factor structure of the SSPS-R was found to be reasonably congruent with the theoretical domains of the alexithymia construct, the scale lacked homogeneity and internal reliability. These results are compared with the reliability and validity of other available measures of alexithymia. Recommendations are offered for the improved assessment of alexithymia in future research studies.  相似文献   
137.
We report a patient with bilateral microphthalmia with cyst, limb anomalies, and multiple facial malformations. This patient has clinical features similar to Waardenburg ophthalmo-acromelic syndrome, cerebro-oculo-nasal syndrome, and craniotelencephalic dysplasia. Although all of these syndromes are characterized by microphthalmia, the presently reported patient does not have the complete pattern of any of these syndromes, It is possible that he has a previously undescribed syndrome, most closely related to the cerebro-oculo-nasal syndrome with malformations outside the craniofacial region. More case reports are needed to further delineate this possibly new syndrome.  相似文献   
138.
139.
BACKGROUND: Although depressed patients demonstrate impaired performance on a range of neuropsychological tests, there is little research that examines either frontal cognitive deficits or possible differences in test performance between melancholic and non-melancholic subtypes. METHODS: Depressed subjects were administered a broad neuropsychological battery. In an overall analysis, 77 depressed subjects were compared with 28 controls. In a second set of analyses, the depressed sample was divided into melancholic and non-melancholic subsets according to DSM-III-R, the CORE system and the Newcastle scale. These depressed subsets were contrasted to controls and with each other using ANCOVA controlling for age, IQ, simple reaction time and Hamilton Depression scores where appropriate. RESULTS: The total depressed sample was impaired on most mnemonic tasks, simple reaction time and Trails B. Similar findings applied to DSM-III-R melancholic and non-melancholic subjects. When defined by the CORE and Newcastle (narrower definitions of melancholia), melancholic patients were additionally impaired on WCST (perseverative response) and (for Newcastle) digit symbol substitution. In contrast, the cognitive performance of the CORE and Newcastle-defined non-melancholic patients was largely unimpaired. CONCLUSIONS: Using narrower definitions of melancholia, i.e. CORE and (in particular) Newcastle, melancholic patients were impaired on mnemonic tasks and tasks of selective attention, and set-shifting while non-melancholic subjects were largely unimpaired in their cognitive performance. These differences may be due to impairment of specific neuroanatomical regions in narrowly defined melancholic patients, in particular the anterior cingulate.  相似文献   
140.
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