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   163433篇
  免费   10328篇
  国内免费   1214篇
耳鼻咽喉   2274篇
儿科学   3087篇
妇产科学   3747篇
基础医学   24186篇
口腔科学   3409篇
临床医学   16019篇
内科学   30849篇
皮肤病学   4360篇
神经病学   12056篇
特种医学   8122篇
外科学   21903篇
综合类   2169篇
现状与发展   5篇
一般理论   81篇
预防医学   10052篇
眼科学   4680篇
药学   13653篇
中国医学   1653篇
肿瘤学   12670篇
  2023年   986篇
  2022年   2740篇
  2021年   4823篇
  2020年   2465篇
  2019年   3585篇
  2018年   4401篇
  2017年   3232篇
  2016年   4197篇
  2015年   5655篇
  2014年   7234篇
  2013年   8543篇
  2012年   12725篇
  2011年   12515篇
  2010年   7694篇
  2009年   6595篇
  2008年   9280篇
  2007年   9134篇
  2006年   8385篇
  2005年   7989篇
  2004年   7153篇
  2003年   6229篇
  2002年   5399篇
  2001年   4392篇
  2000年   4031篇
  1999年   3296篇
  1998年   1319篇
  1997年   994篇
  1996年   959篇
  1995年   862篇
  1994年   751篇
  1993年   643篇
  1992年   1572篇
  1991年   1571篇
  1990年   1353篇
  1989年   1236篇
  1988年   1154篇
  1987年   1030篇
  1986年   1010篇
  1985年   882篇
  1984年   644篇
  1983年   563篇
  1982年   399篇
  1981年   377篇
  1980年   338篇
  1979年   519篇
  1978年   406篇
  1977年   388篇
  1976年   342篇
  1974年   358篇
  1973年   327篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
S L Lee 《JAMA》1991,266(2):217-218
  相似文献   
52.
The purpose of this study was to determine the genetic characteristics of foot polydactyly and identify its inheritance pattern by analyzing familial pedigree. Five cases from 2 Korean families were studied: 1 is a family whose members have been affected for 4 generations and the other for 2 generations. Using peripheral blood samples, we performed chromosomal analysis using the banding technique with Giemsa stain and karyotyping. We investigated the shape and structure of 46 chromosomes, looking for translation, deletion, inversion, ring chromosome, and isochromosome abnormalities. All peripheral blood samples demonstrated no chromosomal abnormalities, though the genetic nature of foot polydactyly and a new genetic locus was identified recently by other studies. Familial pedigree analysis suggested that polydactyly was inherited as an autosomal dominant trait in the first family. The mode of inheritance for the second family could not be determined due to an insufficient number of family members. The result of this study brought us to the conclusion that, while genetic factors play a major role in polydactyly, other factors may contribute to its occurrence.  相似文献   
53.
High cord blood immunoglobulin E (cbIgE) is known to be associated with increased risks of atopic diseases in childhood. The relationship between genetic polymorphisms and high cbIgE has not been well documented. A cross-sectional study was conducted to assess the association between cbIgE and genetic polymorphisms of interleukin (IL)-4 -590C/T, the beta-subunit of the high-affinity receptor for IgE (FcepsilonRI-beta) E237G, lymphotoxin (LT)-alphaNcoI alleles, and tumor necrosis factor (TNF)-alpha -308G/A. A total of 320 mother-neonate pairs were recruited from four maternity hospitals from different locations of Taiwan. Cord blood was obtained and assayed for cbIgE. Polymerase chain reaction followed by restriction fragment length polymorphism was used to assess the genotypes. Three hundred pairs of mothers and neonates were included in the final analysis. Infants with IL-4 -590 C allele were found to have higher risk of elevated cbIgE (> or =0.35 IU/ml, 24.3%) (p = 0.004). After adjusting for gender, birth order, maternal age, and history of allergic disease in maternal and paternal families, odds ratios for CC and CT genotypes were 4.41 and 3.16 (95% confidence interval 0.78-22.67, and 1.66-6.13), respectively, using TT genotype as reference. The genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha were not associated with cbIgE before or after the adjustment. Our finding suggested a significant association of cbIgE with genetic polymorphism of IL-4 -590C/T, but not with the genotypes of FcepsilonRI-beta, LT-alpha, and TNF-alpha.  相似文献   
54.
OBJECTIVE: To establish if there is a role for gabapentin or nortriptyline in the treatment of chronic orchialgia. METHODS: Twenty-six consecutive patients with chronic orchialgia were seen in the chronic pain clinic by a multidisciplinary team. A pain questionnaire was completed prior to commencing either gabapentin or nortriptyline. They were reviewed at 3 months and a repeat questionnaire completed. A 50% improvement in pain was considered successful. RESULTS: Complete data was available for 19 patients. Overall, 61.5% of patients commenced on gabapentin and 66.6% of patients commenced on nortriptyline had a greater than 50% improvement in pain. Patients with post-vasectomy testicular pain were considered as a subgroup. None of these patients had a greater than 50% improvement in pain. However, 80% of patients in the subgroup with idiopathic chronic orchialgia had a greater than 50% improvement in pain. CONCLUSION: Although this is a small study, it appears that gabapentin and nortriptyline are effective in the treatment of idiopathic chronic orchialgia but not post-vasectomy pain.  相似文献   
55.
56.
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   
57.
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   
58.
Activated macrophages are known to oxidatively metabolize L-arginine to nitric oxide and citrulline. We have recently shown that nitric oxide is a potent inhibitory molecule in the in vitro rat mixed-splenocyte culture, resulting in inhibition of proliferation and cytolytic T-cell induction. We undertook this study using the sponge matrix allograft model in the rat to determine whether nitric oxide plays a role in an in vivo allograft response. Our experiments showed that on day 6 after grafting, when cytolytic activity of allograft-infiltrating cells is first detected, allogeneic graft fluid contains higher levels of NO2-/NO3- (the stable endproducts of nitric oxide metabolism) than syngeneic graft fluid. Furthermore, evaluation of the supernatants of cultured graft-infiltrating cells revealed that allogeneic graft-infiltrating cells spontaneously produce higher amounts of nitric oxide than syngeneic graft-infiltrating cells. The nitric oxide production was inhibited in the presence of NG-monomethyl-L-arginine (NMA), the competitive inhibitor of nitric oxide production. Most of the nitric oxide production was observed in the adherent macrophage fraction of the allograft-infiltrating cells. When allograft-infiltrating cells were cultured in the presence of NMA, donor-specific cytolytic activity was observed, whereas allograft-infiltrating cells cultured in the absence of NMA showed no cytolytic activity. These data show that nitric oxide production may play an important regulatory role in the allograft response.  相似文献   
59.
Renal function was evaluated in 104 patients with severe chronic heart failure whom we treated with captopril or enalapril. Seventy patients showed no change or an improvement in renal function (group A), and 34 patients developed functional renal insufficiency (group B). Before converting-enzyme inhibition, group B patients received higher doses of furosemide (p less than 0.02) and had lower central venous pressures (p less than 0.05) than group A patients. After 1 to 3 months of converting-enzyme inhibition, an excessive reduction in left ventricular filling pressure (to less than 15 mm Hg) or mean arterial pressure (to less than 60 mm Hg) was noted in 28 of 34 (82%) patients in group B but in only 22 of 70 patients in group A (31%) (p less than 0.001). At the end of the study, drug-induced azotemia resolved after a reduction in the dosage of diuretics, despite unaltered treatment with captopril and enalapril. Hence, the deterioration of renal function after converting-enzyme inhibition in heart failure is not a toxic or immunologic reaction to therapy but results from specific hemodynamic events that can be ameliorated by sodium repletion.  相似文献   
60.
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