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   13089篇
  免费   1059篇
  国内免费   68篇
耳鼻咽喉   249篇
儿科学   341篇
妇产科学   171篇
基础医学   1421篇
口腔科学   270篇
临床医学   1482篇
内科学   2465篇
皮肤病学   182篇
神经病学   1506篇
特种医学   409篇
外科学   1563篇
综合类   557篇
一般理论   3篇
预防医学   1277篇
眼科学   255篇
药学   1113篇
中国医学   33篇
肿瘤学   919篇
  2021年   124篇
  2020年   106篇
  2019年   158篇
  2018年   185篇
  2017年   146篇
  2016年   156篇
  2015年   339篇
  2014年   444篇
  2013年   574篇
  2012年   689篇
  2011年   815篇
  2010年   416篇
  2009年   421篇
  2008年   595篇
  2007年   782篇
  2006年   638篇
  2005年   637篇
  2004年   626篇
  2003年   581篇
  2002年   507篇
  2001年   242篇
  2000年   245篇
  1999年   223篇
  1998年   166篇
  1997年   148篇
  1996年   151篇
  1995年   132篇
  1994年   118篇
  1993年   127篇
  1992年   211篇
  1991年   204篇
  1990年   176篇
  1989年   159篇
  1988年   164篇
  1987年   176篇
  1986年   159篇
  1985年   167篇
  1984年   183篇
  1983年   159篇
  1982年   162篇
  1981年   156篇
  1980年   118篇
  1979年   123篇
  1978年   140篇
  1977年   103篇
  1976年   112篇
  1975年   114篇
  1974年   95篇
  1973年   77篇
  1968年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
目的:采用几种不同类型的炎症动物模型对AGE的抗炎作用进行研究。方法:大鼠角叉菜胶性足肿胀,醋酸诱导的小鼠腹腔毛细血管通透性增高,小鼠羧甲基纤维素囊中的白细胞数目,大鼠巴豆油性气囊肿的形成。结果:连续灌胃给药5天,AGE(5、10g/kg)可以显著抑制角叉菜胶所致的大鼠足肿胀、醋酸所致的小鼠腹腔毛细血管通透性增高、小鼠羧甲基纤维素囊中白细胞的游出数目以及大鼠巴豆油性气囊的形成。结论:藤茶提取物具有显著的抗炎活性。  相似文献   
12.
13.
D L Marshall  A L Harvey 《Toxicon》1989,27(4):493-498
Venom from the scorpion Pandinus imperator potently and selectively blocks voltage-gated K+ channels in bullfrog neurones (Pappone, P. A. and Cahalan, M. D. 1987, J. Neurosci. 7, 3300-3305). Its effects on neuromuscular transmission have now been assessed. Twitch tension studies on chick biventer cervicis preparations showed that the venom (1 microgram/ml and above) significantly augmented responses to nerve but not muscle stimulation; there was little change in postjunctional sensitivity to cholinoceptor agonists or K+-induced depolarization. Electrophysiological studies on mouse triangularis sterni preparations revealed that the venom had no effect on spontaneous transmitter release, but increased evoked transmitter release. Extracellular recordings of nerve terminal action potentials showed that the venom selectively reduced the component of the waveform associated with K+ currents. These results confirm that this venom can selectively block neuronal K+ currents, and they show that this can facilitate the release of acetylcholine at the neuromuscular junction.  相似文献   
14.
J N Harvey  M E Denyer    P DaCosta 《Gut》1989,30(5):691-694
We describe a patient with extensive ischaemic necrosis of the ileum as a result of elastic vascular sclerosis (EVS). A 2 cm carcinoid tumour was located nearby with microscopic evidence of spread to regional lymph nodes. Severe intestinal ischaemia caused by carcinoid associated EVS may be the presenting feature of small carcinoid tumours resulting in their early diagnosis.  相似文献   
15.
The objective of this study is to determine whether a normal fetal morphology ultrasound scan in women older than 35 years reduces the risk of aneuploidy. We reviewed the results of amniocentesis and second trimester sonogram in all women older than 35 years from 1991 to 1995. None had prior screening. We excluded fetuses with structural anomalies. We determined the sensitivity and specificity of minor markers in detecting Down syndrome and also determined the reduction in risk of a normal sonogram. Among the 2060 women older than 35 years giving birth during the study period, 16 (0.78%) delivered an infant with Down syndrome. Of the 16 fetuses, two had no prenatal testing or ultrasound, two had invasive testing but no second trimester sonogram, five had a normal sonogram and seven had one or more sonographic markers of Down syndrome. At least 17% of women older than 35 years did not participate in prenatal testing or ultrasound. Ultrasound detected Down syndrome with a sensitivity of 59% (95% confidence interval: 45–72%), a false‐positive rate of 10.6% (9.4–11.8%) and a positive predictor value of 1 in 9. The likelihood of having normal karyotype if the sonogram was normal was 0.46 (0.31–0.61). In women older than 35 years, a normal second trimester sonogram reduces the risk of Down syndrome by more than 50%. At least 17% of women older than 35 years do not participate in prenatal testing or ultrasound.  相似文献   
16.
17.
18.
Neuro-muscular transmission in the extrinsic muscles of the eye   总被引:5,自引:0,他引:5  
  相似文献   
19.
PURPOSE: To compare measured visual field extent for a 6 degrees stimulus (typical size used in studies of infants) with a 1.5 degrees stimulus (similar to the largest size used in Goldmann perimetry) in young infants. METHODS: A total of 120 infants (60 each at 3.5 months and 7 months of age) and 24 adults were tested monocularly with a kinetic perimetry procedure using a black double-arc perimeter. Each subject was tested with either a 6 degrees or 1.5 degrees white sphere, which was mounted on a black wand and moved smoothly toward the intersection of the perimeter arms at 3.4 degrees /s. Visual field extent along each perimeter arm was defined as the median of 2 to 3 measurements of the position of the leading edge of the stimulus when the subject made an eye movement toward the stimulus. RESULTS: The 6 degrees stimulus produced larger measured visual field extent than the 1.5 degrees stimulus in 3.5-month olds (temporal field only) and in 7-month olds (nasal and temporal field), but not in adults. CONCLUSIONS: Using the testing conditions of the present study, increasing stimulus size beyond the largest used in a Goldmann perimeter (approximately 2 degrees) increases measured visual field extent in young infants, but not in adults. This may relate to differences in peripheral summation areas or to differences in attentional factors between infants and adults.  相似文献   
20.
BACKGROUND: Effects of risperidone on cognitive function in children with disruptive behavior disorders (DBDs) and subaverage intelligence quotient (IQ) were assessed. METHODS: Data from two 6-week, double-blind, placebo-controlled studies (n = 228) were combined, as were three 1-year, open-label studies (n = 688). Patients with DBDs and subaverage IQ, 5 to14 years, received placebo or risperidone .02 to .06 mg/kg/day. Cognitive measures included the Continuous Performance Task (CPT) and Verbal Learning Test for Children (VLT-C). Efficacy was assessed using the Nisonger Child Behavior Rating Form (NCBRF). Adverse events were collected via spontaneous report; sedation was assessed using visual analog scale. RESULTS: Improvements on the NCBRF Conduct Problem subscale were significantly greater for risperidone- versus placebo-treated patients (-15.8 vs. -6.4, p < .0001) in short-term studies; significant reductions were observed in long-term studies (-16.3, p < .0001). No overall decline and some significant improvement in attention (CPT) and memory (VLT-C) were noted regardless of treatment in short-term studies. VLT-C improved significantly (p < .0001) for both groups, with no difference between treatment groups. Improvements in memory (VLT-C) and attention (CPT) were noted in long-term studies. Somnolence/sedation did not affect cognitive function. CONCLUSIONS: Cognitive function was not altered by risperidone in short-term studies and was maintained or improved with one year of treatment in children with DBDs and subaverage IQ, potentially representing age-appropriate gains.  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