全文获取类型
收费全文 | 13268篇 |
免费 | 991篇 |
国内免费 | 781篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 110篇 |
妇产科学 | 71篇 |
基础医学 | 1524篇 |
口腔科学 | 232篇 |
临床医学 | 640篇 |
内科学 | 807篇 |
皮肤病学 | 155篇 |
神经病学 | 354篇 |
特种医学 | 192篇 |
外国民族医学 | 4篇 |
外科学 | 388篇 |
综合类 | 2395篇 |
现状与发展 | 1篇 |
预防医学 | 1051篇 |
眼科学 | 132篇 |
药学 | 2597篇 |
1篇 | |
中国医学 | 3842篇 |
肿瘤学 | 311篇 |
出版年
2024年 | 120篇 |
2023年 | 173篇 |
2022年 | 358篇 |
2021年 | 477篇 |
2020年 | 422篇 |
2019年 | 356篇 |
2018年 | 380篇 |
2017年 | 476篇 |
2016年 | 530篇 |
2015年 | 487篇 |
2014年 | 870篇 |
2013年 | 1029篇 |
2012年 | 992篇 |
2011年 | 1050篇 |
2010年 | 810篇 |
2009年 | 647篇 |
2008年 | 678篇 |
2007年 | 699篇 |
2006年 | 560篇 |
2005年 | 471篇 |
2004年 | 367篇 |
2003年 | 328篇 |
2002年 | 303篇 |
2001年 | 225篇 |
2000年 | 192篇 |
1999年 | 187篇 |
1998年 | 159篇 |
1997年 | 131篇 |
1996年 | 109篇 |
1995年 | 103篇 |
1994年 | 103篇 |
1993年 | 85篇 |
1992年 | 93篇 |
1991年 | 57篇 |
1990年 | 57篇 |
1989年 | 62篇 |
1988年 | 58篇 |
1987年 | 39篇 |
1985年 | 90篇 |
1984年 | 82篇 |
1983年 | 79篇 |
1982年 | 74篇 |
1981年 | 69篇 |
1980年 | 73篇 |
1979年 | 56篇 |
1978年 | 41篇 |
1977年 | 51篇 |
1976年 | 39篇 |
1975年 | 48篇 |
1974年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 23 毫秒
11.
12.
BACKGROUND: Reduced Th1 and elevated Th2 cytokine responses are considered to be a principal mechanism in the generation of the inflammation leading to the manifestations of atopic disease in the skin of atopic dermatitis and in the airways of asthma. If reduced Th1 and elevated Th2 responses are principal determinants of the manifestation of atopic disease it might be expected that subjects with established disease would exhibit differences in their cytokine profiles as compared with atopic patients without clinical disease. OBJECTIVE: To determine whether asymptomatic atopic children exhibit a cytokine imbalance similar to that seen in patients with established atopic disease or if they behave like non-atopic controls. Cytokine responses in a group of children with elevated IgE but no clinical manifestations of disease, atopic children with established disease and non-atopic controls were compared. METHODS: We examined allergen-induced (house dust mite, HDM, rye grass pollen and RYE) cytokine responses in parallel with polyclonal (staphylococcal enterotoxin B, SEB) cytokine responses in a group of children with elevated serum IgE levels without current or past evidence of atopic disease (median age 6.6 years) and compared these with a non-atopic control group (median age 6.5 years) and a group of children with atopic disease (median age 6.7 years). RESULTS: Symptomatic atopic children had reduced SEB-induced IFN-gamma and increased SEB-induced IL-4 and IL-5 as compared with non-atopic controls. In contrast, SEB-induced IFN-gamma, IL-4 and IL-5 production in asymptomatic atopics was not significantly different from the non-atopic control subjects. Allergen-induced Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production was increased in both symptomatic atopics and asymptomatic atopics when compared with non-atopic controls. CONCLUSION: The defect in polyclonally induced IFN-gamma production was associated with the clinical manifestation of atopic disease but not the atopic stateper se. This suggests that the global reduction in IFN-gamma is the key determinant of the development of overt atopic disease. In contrast, elevated allergen-induced Th2 cytokine responses in children related to the atopic state per se irrespective of the presence of clinical atopic disease. 相似文献
13.
S. Ju
wiak T. Raiska T. Dutkiewicz U. Cioch B. Olenderek B. Krasowska L. Rzewicka Z. Juzyszyn J. Wjcicki L. Samochowiec 《Phytotherapy research : PTR》1992,6(3):141-145
Cernitins are preparations obtained from plant pollen which contain numerous compounds of potential biological significance. This work deals with the influence of cernitins upon acute paracetamol toxicity in mice. The survival rate and indices of hepatic injury: aminotransferase and alkaline phosphatase activities, bilirubin level in serum, glutathione and cytochrome P-450 content in liver, liver weight, histopathologic picture of the liver and presence of glycogen and lipids in stained liver sections, under different experimental protocols, were determined. It was found that cernitins are able to increase the survival rate of mice and reduce liver injury in acute paracetamol poisoning. Cernitins are more effective when administered after, rather than before, a dose of paracetamol. The possible mechanism through which cernitins may act is discussed. 相似文献
14.
猕猴桃中药复方制剂对血清SOD及MDA含量的影响 总被引:4,自引:0,他引:4
猕猴桃中药复方制剂系采用猕猴桃汁为基质,配加绞股蓝、丹参等中药的有效成分制成。为了研究它的保健作用,在63例50岁以上、无急性疾病的中、老年人,36例30~49岁健康的青年,32例14~17岁健康的少年中进行试验,10ml每日2次连续服用30天后,中老年人血液SOD显著增高,70岁以上老人平均增高2.8倍,血清MDA明显下降,70岁以上平均下降87.5%。 相似文献
15.
目的:观察自拟胃胆宁汤治疗胆汁反流性胃炎的临床疗效。方法:选符合标准的该病患者82例,随机分为两组,治疗组54例予自拟胃胆宁汤,对照组28例用吗丁啉片及雷尼替丁,两组治疗4周为1疗程。结果:治疗组痊愈20例,显效13例,有效16例,无效5例,总有效率为90.74%(95%CI=83.01%~98.48%);对照组痊愈5例,显效6例,有效9例,无效8例,总有效率为71.43%(95%CI=54.70%~88.16%);两组综合疗效比较,有显著性差异(u=2.3027,P=0.0215)。结论:自拟胃胆宁汤治疗胆汁反流性胃炎疗效优于吗丁啉及雷尼替丁,其收益为OR=0.25(95%CI=0.07~0.87),NNT=5(95%CI=2.78~37.88)。 相似文献
16.
Tsuneo Namba Hongxi Xu Shigetoshi Kadota Masao Hattori Tooru Takahashi Yasuhiko Kojima 《Phytotherapy research : PTR》1993,7(3):227-230
The inhibitory effects of glycoproteins separated from a hot water extract of corn silk (U-CSE) on the formation of IgE antibodies after primarily and secondarily challenged responses with dinitrophenyl (DNP)-ovalbumin (OVA) antigen in mice were investigated using the passive cutaneous anaphylaxis (PCA) test. When U-CSE was given intranasally or intraperitoneally the day before primary immunization, IgE antibody production was strongly inhibited. Furthermore, it was found that new formation of IgE antibodies was readily inhibited by U-CSE administration in mice with high levels of IgE after primary immunization. It was also found that U-CSE markedly suppressed IgE antibody formation in secondarily challenged responses with the antigen. U-CSE may be clinically applicable to type I allergic diseases. 相似文献
17.
Significance of sampling height of airborne particles for aerobiological information 总被引:4,自引:2,他引:2
Pollen and spore counts from Burkard traps for routine pollen and spore sampling placed at 15 m above ground and at ground level were compared. Daily counts of most pollen types were higher on the ground than at roof level, but the counts were significantly correlated. The ratios of pollen frequencies at high and low levels varied between 1.0 and 11.5. The most prominent differences were recorded for herbaceous pollen (e.g. Artemisia counts 11.5 and Poaccae counts 4.4 times higher at ground level) and in Botrytis and Ustilaginales spores. Tree pollen grains and basidiomycetous spores were more equally distributed. Wind speed did not affect the variation of pollen frequencies at either height. Large spores are not so unevenly distributed as previously supposed. Artemisia and grass pollen was detected 1 to 2 weeks earlier at ground level than on the roof. It is therefore concluded that especially the beginning of flowering should be monitored at a low level. 相似文献
18.
We report a patient with metastatic thyroid carcinoma invading the esophagus in whom barium and MR examinations revealed an expansile intraluminal mass indistinguishable from that of a primary esophageal malignancy. Metastatic thyroid carcinoma should therefore be included in the differential diagnosis of an expansile esophageal mass. As in our patient, MR imaging may be useful for showing that the mass originates in the thyroid gland. 相似文献
19.
The influence of a fraction obtained from Galeopsis ladanum L. on the central nervous system of rodents was examined. The results of these investigations show that the fraction impeded CNS activity. It is practically nontoxic and at a dose of 2000 mg/kg i.p. it does not have a soporific influence on mice. It reduces considerably the spontaneous locomotor activity of mice as well as the locomotor activity of mice stimulated by caffeine, but did not influence the locomotor activity induced by amphetamine. The extract did not exhibit a synergetic effect with barbiturates. The results suggest that the pharmacological activity of the extract resembled the activity of drugs which generally depress the CNS, being on the border between ataractic and sedative drugs. 相似文献
20.
A major allergen of Parietaria officinalis, a species responsible for a large number of respiratory allergies in Mediterranean areas, has been identified and characterized. This allergen (Pol) was found in the fraction which precipitates between 70 and 100% ammonium sulphate saturation. Pol showed a molecular weight of 15,000 daltons as determined by SDS-PAGE and HPLC. The pI of Pol was in the pH region 4-6, IEF showing four major bands. Two major bands were shown by CIE, CRIE and immunoblotting; major contaminants or aggregates were also revealed by the latter technique and by HPLC. Pol showed an allergic specific activity 2 times higher than the crude extract; moreover it was shown to be a major allergen since it inhibited 29 out of 30 sera from allergic patients sensitive to P. officinalis. 相似文献