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   379100篇
  免费   24172篇
  国内免费   2811篇
耳鼻咽喉   5188篇
儿科学   8203篇
妇产科学   10076篇
基础医学   53143篇
口腔科学   11823篇
临床医学   30085篇
内科学   78308篇
皮肤病学   8545篇
神经病学   27182篇
特种医学   13923篇
外国民族医学   82篇
外科学   60564篇
综合类   9956篇
现状与发展   1篇
一般理论   64篇
预防医学   17425篇
眼科学   9437篇
药学   30975篇
  1篇
中国医学   2195篇
肿瘤学   28907篇
  2021年   2607篇
  2019年   2721篇
  2018年   4519篇
  2017年   3433篇
  2016年   3520篇
  2015年   4019篇
  2014年   5693篇
  2013年   7372篇
  2012年   10013篇
  2011年   10195篇
  2010年   6190篇
  2009年   5839篇
  2008年   9452篇
  2007年   10282篇
  2006年   10202篇
  2005年   9269篇
  2004年   8775篇
  2003年   8518篇
  2002年   8193篇
  2001年   28248篇
  2000年   28780篇
  1999年   23651篇
  1998年   5165篇
  1997年   4248篇
  1996年   3832篇
  1995年   3481篇
  1994年   3108篇
  1993年   2846篇
  1992年   16048篇
  1991年   14816篇
  1990年   14158篇
  1989年   13965篇
  1988年   12583篇
  1987年   12064篇
  1986年   11106篇
  1985年   10328篇
  1984年   6916篇
  1983年   5601篇
  1982年   2718篇
  1979年   5481篇
  1978年   3347篇
  1977年   2972篇
  1975年   2641篇
  1974年   3065篇
  1973年   2865篇
  1972年   2831篇
  1971年   2776篇
  1970年   2515篇
  1969年   2547篇
  1968年   2253篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
161.
162.
163.
Effects of immobilization and footshock stress on locomotor activity in different areas of an open field were examined in mice. Center region activity, peripheral region activity and total activity were used as measurement indices. These results indicate that both immobilization and footshock stress significantly increased total activity across 24 min of behavioral testing. Further analyses revealed that the difference in total activity between the experimental and control groups were mainly attributal to an increase in center region activity. Both stress manipulations markedly augmented peripheral region activity for only the first 6 min. More important, when the proportion of center to peripheral activity was used as an index, both experimental groups manifested an inverted U shape relationship with the maximum effect occurring between 13-18 min of behavioral testing. Similarities of these activity measures in response to different stressors suggests that common neurochemical and/or neurohormonal mechanisms may mediate these behavioral changes.  相似文献   
164.
A new method of determining urinary polyamine concentration was compared with other techniques, namely, high pressure liquid chromatography (HPLC) and a polyamine test-enzyme kit. The values obtained by the new method, HPLC, and polyamine test-enzyme kit correlated well for all the fractions: diamine, spermidine and spermine. The correlation between the new method and the polyamine test-enzyme kit gave r = 0.9702, y = 1.1359x + 5.1266 (n = 48).  相似文献   
165.
Four patients with cavernous hemangioma of face and neck were evaluated with magnetic resonance imaging. Pathologically, soft tissue cavernous hemangiomas are characterized by small feeding arteries and large blood poolings. Arteriography usually fails to demonstrate the extent of the lesion. Computed tomography does not allow differentiation between these lesions and surrounding normal tissues. Magnetic resonance clearly demonstrates hemangiomas with good contrast between lesion and normal tissues. Spin-echo technique with long echo time appears to be particularly useful to delineate these lesions.  相似文献   
166.
167.
168.
Repeated administration of a large dose of methamphetamine (MA) (25 mg/kg, i.p. twice daily for 4 days) to mice enhanced locomotor activity and decreased stereotyped behavior following a subsequent injection of MA. Simultaneous determinations of catecholamines revealed a depletion of brain dopamine. The moderate doses of haloperidol significantly enhanced MA-induced locomotor activity in mice. A significant enhancement of MA-induced locomotor activity was observed in the rats pretreated with 6-hydroxydopamine into the striatum, and this effect correlated negatively with the striatal dopamine level. These results suggest that hypofunction of striatal dopaminergic neuron systems induced by repeated administration of MA may be one of possible mechanisms of the enhancement of MA-induced locomotor activity due to the decrease of stereotyped behavior.  相似文献   
169.
E J Roth  T Park  T Pang  G M Yarkony  M Y Lee 《Paraplegia》1991,29(9):582-589
Brown-Sequard syndrome (BSS) and Brown-Sequard-plus syndrome (BSPS) are characterised by asymmetrical paresis with hypalgesia more marked on the less paretic side. This study examined the clinical features of 38 patients (30 males and 8 females; mean age = 32 years) with traumatic cervical BSS or BSPS who underwent comprehensive inpatient rehabilitation. Twenty two injuries were caused by road traffic accidents, 8 by penetrating injuries, 5 by diving injuries, and 3 by other causes. After an average of 35 days in acute care and 79 days in rehabilitation, 37 patients had increased muscle strength, all 38 patients improved functional abilities, 29 patients walked independently, 34 had spontaneous bladder emptying, 36 were discharged home, and 14 were employed. Statistically significant increases (p less than 0.001) were made in modified Barthel index functional scores between admission and discharge. Patients with BSPS had a better prognosis than did those with 'pure' BSS. Patients with predominant upper limb weakness had more favourable outcomes than did those with predominant lower limb weakness. Few other potentially predictive demographic, injury, or neurological factors were associated with functional outcome. Patients with BSS or BSPS generally have a good prognosis for neurological and functional improvement.  相似文献   
170.
BACKGROUND. A health risk appraisal (HRA) is a tool for health promotion. Conversational microcomputer-based HRAs may be more cost effective than other HRA formats. The acceptability of conversational HRAs, however, has not been demonstrated for older adults. METHODS. We studied the acceptability of a conversational microcomputer-based HRA in a sample of 247 adults at the Minnesota State Fair and the Senior Options Exposition. All users were offered the appraisal via mouse or keyboard interface. Acceptability was measured in terms of user-reported helpfulness, intent to change, time of use, and willingness to view HRA health recommendations. Data on completion time and willingness to view HRA recommendations were collected for Senior Exposition users only. Regression analyses were used to examine the combined impact of interface (mouse or keyboard), location (State Fair or Senior Exposition), age, and sex on user acceptability. Results. Interface and location had no effect on helpfulness or change ratings. Older users rated the appraisal more helpful (P less than .007). Both older and female users reported more intent to change behavior (P = .016, both). Time to use the appraisal was related to interface, age, and sex. Mouse users (P less than .0001), older users (P less than .0001) and female users (P less than .05) took significantly longer to use the appraisal. Significantly more mouse users declined to see recommendations (P less than .02). CONCLUSIONS. Older users can derive as much or more value from conversational health risk appraisals as younger users; however, a mouse interface may be less effective for this age group.  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