全文获取类型
收费全文 | 13410篇 |
免费 | 665篇 |
国内免费 | 184篇 |
专业分类
耳鼻咽喉 | 201篇 |
儿科学 | 3625篇 |
妇产科学 | 915篇 |
基础医学 | 778篇 |
口腔科学 | 68篇 |
临床医学 | 1633篇 |
内科学 | 677篇 |
皮肤病学 | 97篇 |
神经病学 | 461篇 |
特种医学 | 257篇 |
外科学 | 621篇 |
综合类 | 1905篇 |
预防医学 | 1858篇 |
眼科学 | 142篇 |
药学 | 847篇 |
14篇 | |
中国医学 | 119篇 |
肿瘤学 | 41篇 |
出版年
2024年 | 17篇 |
2023年 | 146篇 |
2022年 | 346篇 |
2021年 | 436篇 |
2020年 | 368篇 |
2019年 | 365篇 |
2018年 | 365篇 |
2017年 | 296篇 |
2016年 | 459篇 |
2015年 | 374篇 |
2014年 | 847篇 |
2013年 | 942篇 |
2012年 | 792篇 |
2011年 | 886篇 |
2010年 | 678篇 |
2009年 | 719篇 |
2008年 | 634篇 |
2007年 | 657篇 |
2006年 | 697篇 |
2005年 | 592篇 |
2004年 | 501篇 |
2003年 | 364篇 |
2002年 | 300篇 |
2001年 | 298篇 |
2000年 | 252篇 |
1999年 | 219篇 |
1998年 | 174篇 |
1997年 | 155篇 |
1996年 | 145篇 |
1995年 | 130篇 |
1994年 | 115篇 |
1993年 | 91篇 |
1992年 | 61篇 |
1991年 | 51篇 |
1990年 | 71篇 |
1989年 | 88篇 |
1988年 | 63篇 |
1987年 | 57篇 |
1986年 | 42篇 |
1985年 | 63篇 |
1984年 | 53篇 |
1983年 | 35篇 |
1982年 | 52篇 |
1981年 | 41篇 |
1980年 | 32篇 |
1979年 | 32篇 |
1978年 | 20篇 |
1977年 | 28篇 |
1976年 | 26篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
THOMAS T MACDONALD 《Pediatrics international》1994,36(5):532-536
The human mucosal immune system is structurally mature and has all the necessary cellular components to generate an immune response at birth. However, in the absence of dietary antigens and bacterial flora, there are no secondary follicles in the Peyer's patches and virtually no immunoglobulin A plasma cells in the lamina propria. Reactive follicle centers develop after birth but it takes 2 years for mucosal IgA plasma cell density to reach adult levels. T cells are present in the epithelium and lamina propria at birth, albeit at a lower frequency than later in life and there are major differences in phenotype between T cells in fetal intestine and postnatal intestine. There is no information on the impact of the massive antigenic challenge at birth on the mucosal immune system. Well-documented deficiencies in the ability of the blood T cells of the neonate to produce interleukin-4 and interferon-gamma may also occur in the intestine. It is still an open question whether it is better to try to prevent immunological sensitization of the newborn by avoiding potential allergens (i.e. cow's milk), or whether early exposure (as happens when premature infants are given formula feeds) might tolerize the infant. Hydrolysed cow's milk formulae are probably less antigenic than whole cow's milk and have been widely used in the treatment of cow's milk allergy. Some thought is now being given as to whether the prophylactic use of hydrolysates can reduce cow's milk allergy in ‘at-risk’ infants. 相似文献
12.
阿奇霉素替代激素治疗婴幼儿喘息性支气管炎临床研究 总被引:6,自引:0,他引:6
目的评价阿奇霉素治疗婴幼儿喘息性支气管炎的疗效并探讨其作用机制。方法婴幼儿喘息性支气管炎60例,随机分为2组,各30例,A组用阿奇霉素治疗,B组用地塞米松治疗,分别观察3d后的临床疗效;2组均测定其外周血清IL-4,IFN-γ浓度变化,并与15例健康婴幼儿(对照组)血清IL-4,IFN-γ浓度对比。结果A组与B组临床总有效率差异无统计学意义;整个喘息性支气管炎组与正常对照组相比IFN-γ和IL-4值差异均有统计学意义,IFN-γ下降,IL-4升高;各组治疗前与治疗后相比差异均有统计学意义,A组治疗后血清IFN-γ浓度增高、IL-4浓度下降;B组治疗后血清IFN-γ浓度下降、IL-4浓度也下降,且2组IFN-γ/IL-4值均显著升高。结论阿奇霉素治疗婴幼儿喘息性支气管炎有较好的疗效,能与地塞米松有同样的调节TH1及TH2细胞因子使之趋于平衡,并且有更好的促进细胞免疫作用。 相似文献
13.
Ming-Shian Tsai Wen-Hsi Lin Wen-Ming Hsu Hong-Shiee Lai Po-Huang Lee Wei-Jao Chen 《Journal of gastrointestinal surgery》2008,12(12):2191-2195
Background/aims Surgical resection of choledochal cysts (CC) has become standard treatment. However, surgery is not universally recommended
in early infancy and/or asymptomatic patients. In order to investigate the optimal timing of CC excision, we analyzed clinicopathological
data and surgical results from different age groups.
Material and methods This retrospective review included 107 patients (77 females, 30 males) who underwent CC resection at the National Taiwan University
Hospital between January 1988 and December 2005. Patient demographic, clinical, and surgical data were collected and analyzed.
Results The patients were divided into three groups according to age at the time of surgery: <1 year old (group I, n = 26), 1−16 years old (group II, n = 48), and >16 years old (group III, n = 33). About two thirds of the patients in group I had jaundice, while abdominal pain related to inflammation was the commonest
symptom in groups II and III. Group I suffered significantly fewer surgical complications and less severe liver fibrosis than
groups II or III.
Conclusion CC surgery in infancy and in asymptomatic patients is safe and may prevent the complications of this condition. The results
support a recommendation for early excision. 相似文献
14.
Cheryl M. Mccormick Priscilla Kehoe Sandra Kovacs 《International journal of developmental neuroscience》1998,16(3-4)
Repeated isolation of neonatal rats produces persistent changes in physiology and behavior. In Experiment 1, we examined changes in plasma corticosterone (CORT) levels as a possible mechanism for the effects of isolation. Pups that were isolated from their mother and the nest for 1 h per day on postnatal days (PND) 2–9 were compared to control litters of pups that were either nonhandled or handled but not isolated. On PND 2, compared to nonhandled pups, handled pups had elevated CORT levels that returned to baseline levels within 30 to 60 min of return to the home cage. No significant elevation of CORT levels were found in handled pups on PND 9. The CORT levels of isolated pups were over twice those of nonhandled pups on PND 2 and four times those of nonhandled pups on PND 9. In Experiment 2, we investigated whether the increased CORT release in response to isolation on PND 9 was the result of the pups treatment on the previous six days as against an effect of maturation. Plasma CORT levels were measured in rat pups that were either isolated, handled or nonhandled on PNDs 2–8 during the conditions of isolation, handling and nonhandling on PND 9. There were no differences among the groups in basal plasma levels of CORT. Handling on PND 9 did not result in elevated CORT levels in any of the groups. All three groups showed a significant increase in plasma CORT levels after isolation on PND 9. However, the CORT response to isolation of pups previously isolated on PND 2–8 were significantly higher than pups that were either handled or nonhandled on PNDs 2–8. Thus, daily episodes of isolation potentiate the hypothalamic-pituitary-adrenal response to stress. 相似文献
15.
Friedrich Manz Hermann Kalhoff Thomas Remer 《Pediatric nephrology (Berlin, Germany)》1997,11(2):231-243
In early infancy, complex disorders of acid base metabolism are more frequent than in any other age group, with a predisposition
to metabolic acidosis due to an age-related low renal capacity for acid excretion and an unphysiologically high actual renal
acid load in nutrition with common formulas. Recently in preterm and small-for-gestational-age infants, persistent maximum
renal net acid excretion (NAE) with subnormal or normal blood acid base status, impaired weight gain, and adaptive hormonal
reactions have been observed. Incipient late metabolic acidosis is one example of a mixed disorder of acid base metabolism
with maximum renal NAE in early infancy. Alkali therapy is highly effective and can be realized both on an individual basis,
using urine pH screening as a diagnostic criterium for maximum renal acid stimulation, or on a general preventive level using
modified standard formula with a reduced actual renal NAE similar to that seen on alimentation with human milk. From an integrated
point of view, the low glomerular filtration rate and renal capacity for acid excretion beyond the developmental age of more
than 44 weeks, may well be interpreted as the result of a specific adaptation to breast feeding sparing energy, and thus an
evolutionary advantage for the survival of mother and child.
Received July 10, 1996; received in revised form and accepted October 7, 1996 相似文献
16.
S. Hunot V. Bernard B. Faucheux F. Boissière E. Leguern C. Brana P. P. Gautris J. Guérin B. Bloch Y. Agid E. C. Hirsch 《Journal of neural transmission (Vienna, Austria : 1996)》1996,103(8-9):1043-1052
Summary Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for dopaminergic neurons. Since dopaminergic neurons degenerate in Parkinson's disease, this factor is a potential therapeutical tool that may save dopaminergic neurons during the pathological process. Moreover, a reduced GDNF expression may be involved in the pathophysiology of the disease. In this study, we tested whether altered GDNF production may participate in the mechanism of cell death in this disease. GDNF gene expression was analyzed by in situ hybridization using riboprobes corresponding to a sequence of the exon 2 human GDNF gene. Experiments were performed on tissue sections of the mesencephalon and the striatum from 8 patients with Parkinson's disease and 6 control subjects matched for age at death and for post mortem delay. No labelling was observed in either group of patients. This absence of detectable expression could not be attributed to methodological problems as a positive staining was observed using the same probes for sections of astroglioma biopsies from human adults and for sections of a newborn infant brain obtained at post-mortem. These data suggest that GDNF is probably expressed at a very low level in the adult human brain and its involvement in the pathophysiology of Parkinson's disease remains to be demonstrated. GDNF may represent a powerful new therapeutic agent for Parkinson's disease, however. 相似文献
17.
目的进一步认识婴幼儿患者实施外科手术的危险性及规范手术配合程序的重要性,提高配合质量,提出手术配合要点。方法回顾近几年168例婴幼儿患者外科手术护理配合,同时结合自己的临床实际经验和手术配合中的体会,提炼出婴幼儿患者手术的护理配合要点。结果婴幼儿患者手术的配合要做好术前评估,掌握患者心肺主要脏器的功能情况,做好充分准备,手术室感染控制,术中的各项检测,监测输液量、速度及体温维持情况。结论掌握婴幼儿患者手术的护理配合要点,可提高手术配合质量和手术成功率。 相似文献
18.
新生鼠和成年鼠脑7种微量元素含量的比较 总被引:1,自引:0,他引:1
利用高频电感耦合等离子体原子发射光谱法(ICP-AES)测定Sprunge-Dawley大鼠新生期大脑皮层、海马、小脑、间脑和脑桥等部位的锌、铁、铜、锰、铬、锶、钼等7种微量元素的含量,并与成年动物做了比较。结果表明:(1)新生期大鼠全脑7种微量元素含量的多寡依次为:锌、铁、铬、锶、锰、铜、钼;成年期时钢跃居第四位,总含量低于新生期。(2)脑内不同部位微量元素的含量不同。新生大鼠海马和小脑内多数元素含量高于其他脑区,钼在间脑和海马中含量较高。成年鼠皮层、海马微量元素含量较高,皮层内铜、锶、钼含量最低。 相似文献
19.
Journal of Anesthesia - 相似文献
20.
目的 探讨新生儿C6PD缺陷病和晚发性维生素K缺乏症的危害与预防措施。方法 回顾分析1995-2000年儿内科住院的1周-2月(不含2月)的婴儿3104例次,其中病死56例。结果 1周-2月的小婴儿占住院患儿的19.34%,其中新生儿G6PD缺陷病239例,占7.70%;晚发性维生素K缺乏症92例,占2.96%。死因的第2、3位分别是晚发性维生素K缺乏症(13例,占23.21%)和新生儿C6PD缺陷病(12例,占21.43%),两者的病死率分别为14.13%和5.02%,极显著高于(x^2=17.59,P<0.01)或相近于(x^2=0.88,P>0.05)肺炎的3.57%。新生儿G6PD缺陷病合并感染占38.49%、低氧血症占23.35%、低血糖占19.25%、酸中毒占15.90%,继发胆红素脑病占13.81%。晚发性维生素K缺乏症出现抽搐占90.22%、胃肠、注射部位出血占60.89%;CT证实颅内出血占98.91%。结论 1周-2月的小婴儿约占住院患儿的两成,新生儿G6PD缺陷病和晚发性维生素K缺乏症的病死率均很高,两者是除肺炎外最主要的死因。提议制定并推广预防这2种疾病的常规措施,并参照国内外相应的现状拟出其具体内容。 相似文献