全文获取类型
收费全文 | 197623篇 |
免费 | 16163篇 |
国内免费 | 7134篇 |
专业分类
耳鼻咽喉 | 1611篇 |
儿科学 | 2573篇 |
妇产科学 | 2167篇 |
基础医学 | 30955篇 |
口腔科学 | 3293篇 |
临床医学 | 14373篇 |
内科学 | 35271篇 |
皮肤病学 | 2683篇 |
神经病学 | 14746篇 |
特种医学 | 4194篇 |
外国民族医学 | 52篇 |
外科学 | 13203篇 |
综合类 | 26086篇 |
现状与发展 | 19篇 |
一般理论 | 6篇 |
预防医学 | 9738篇 |
眼科学 | 1960篇 |
药学 | 31964篇 |
44篇 | |
中国医学 | 8155篇 |
肿瘤学 | 17827篇 |
出版年
2024年 | 514篇 |
2023年 | 3809篇 |
2022年 | 8268篇 |
2021年 | 10023篇 |
2020年 | 7534篇 |
2019年 | 6421篇 |
2018年 | 6184篇 |
2017年 | 6193篇 |
2016年 | 6319篇 |
2015年 | 7436篇 |
2014年 | 11508篇 |
2013年 | 12815篇 |
2012年 | 11365篇 |
2011年 | 13124篇 |
2010年 | 10825篇 |
2009年 | 11086篇 |
2008年 | 10751篇 |
2007年 | 9778篇 |
2006年 | 8726篇 |
2005年 | 7666篇 |
2004年 | 6390篇 |
2003年 | 5717篇 |
2002年 | 4537篇 |
2001年 | 3701篇 |
2000年 | 3125篇 |
1999年 | 2826篇 |
1998年 | 2636篇 |
1997年 | 2446篇 |
1996年 | 2188篇 |
1995年 | 1943篇 |
1994年 | 1762篇 |
1993年 | 1525篇 |
1992年 | 1280篇 |
1991年 | 1207篇 |
1990年 | 991篇 |
1989年 | 832篇 |
1988年 | 793篇 |
1987年 | 665篇 |
1986年 | 600篇 |
1985年 | 945篇 |
1984年 | 900篇 |
1983年 | 631篇 |
1982年 | 639篇 |
1981年 | 511篇 |
1980年 | 431篇 |
1979年 | 353篇 |
1978年 | 230篇 |
1977年 | 193篇 |
1976年 | 183篇 |
1975年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
OBJECTIVES: To assess the effectiveness and safety of additional bedtime H2‐receptor antagonists (H2RAs) in suppressing nocturnal gastric acid breakthrough (NAB) via a systematic review. METHODS: Eligible trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, 2004), MEDLINE (January 1966–June 2004), EMBASE (January 1980–June 2004) and CINAHL (January 1982–June 2004). Additional hand‐searching was conducted on the proceedings of correlated conferences, eight important Chinese journals and references of all included trials. All randomized controlled trials evaluating H2RAs for the control of NAB were eligible for inclusion. The systematic review was conducted using methods recommended by The Cochrane Collaboration. RESULTS: Only two randomized crossover studies, comprising 32 participants, met the inclusion criteria. Because the design, dosage and duration of the treatments were different between the studies, it was not possible to conduct meta‐analysis. There were no consistent conclusions found between the two included studies in evaluating H2RAs for the control of NAB. CONCLUSIONS: No implications for practice at this stage can be concluded. Appropriately designed large‐scale randomized controlled trials with long‐term follow up are needed to determine the effects of additional bedtime H2RAs in suppressing NAB. 相似文献
83.
《Journal of labelled compounds & radiopharmaceuticals》2006,49(4):339-343
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6‐dihydroxy‐2‐mercaptopyrimidine 3 . Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6‐dimethoxy‐2‐methylsulphonylpyrimidine 5 . Compound 5 on condensation with 2‐mercapto‐6‐chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac‐sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]‐thiourea in lieu of thiourea, 14C labelled product 6 , was synthesized with an overall radiochemical yield > 30% (with respect to [14C]‐thiourea) for further evaluations of environmental fate of 6 , in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
84.
目的探讨谷氨酸是否能够影响腺苷A2A受体对一氧化氮合酶(NOS)活力的调节。方法用1000ng/ml脂多糖(LPS)刺激小胶质细胞,分别加入100nmol/L A2A受体激动剂CGS21680以及不同浓度的谷氨酸(0,1,0,25,0,5mmol/L)干预,观察NOS活力变化。结果LPS诱导NOS活力增高,激活A2A受体可以产生抑制作用;0,25及0.5mmoL/L谷氨酸和A2A受体激动剂同时存在时,NOS活力进一步增高。结论高浓度谷氨酸可逆转腺苷A2A受体激动剂抑制升高NOS活力的作用。 相似文献
85.
86.
Fernand Lamisse 《Cahiers de Nutrition et de Diététique》2006,41(6):347-351
Many health-related research studies among Seventh-day Adventists (SDA) were published since 1958. Californian and Norwegian studies have shown that SDA have lower coronary mortality rates than the general population. This finding is usually attributed to the lifestyle advocated by the Seventh-day Adventist church with greater physical activity, lower median BMI, abstention from use of alcohol and tobacco, food habits characterized by a large intake of fruits, vegetables, cereal fiber, unsaturated fatty acids and a low consumption of saturated fats. The results about cancer incidence were discussed. Californian studies have shown significantly decreased relative risk in SDA than in the general population. Japanese studies have also reported lower risk of cancers in men with lifestyles similar to those of SDA. By contrast the Norwegian study of SDA has shown that the risk of cancer seems to be similar to that of the general population. Some studies reported a greater prevalence of type 2 diabetes in the non vegetarian SDA than the vegetarian. Compared with vegetarian, non vegetarian SDA reported more medication use, more chronic diseases, more hospitalizations and surgeries. Lifestyle choices of SDA as above described could prevent a great many coronary artery disease and type 2 diabetes. This lifestyle is now emphasized by French PNNS. 相似文献
87.
88.
89.
目的探讨Survivin在食管癌组织中的表达及其与bcl-2蛋白表达的相关性。方法应用免疫组织化学SP法,检测Survivin、bcl-2蛋白在68例食管癌组织和20例正常食管组织中的表达。结果Survivin蛋白在正常食管组织中低表达或不表达,68例食管癌组织中,49例表达阳性,占72.1%。Survivin蛋白表达与分化程度、淋巴结转移密切相关(P<0.05)。食管癌组织bcl-2蛋白表达阳性、阴性组中,Survivin蛋白阳性表达率分别为94.7%(36/38)和43.3%(13/30),两者比较,差异有统计学意义(P<0.05)。Survivin蛋白表达与bcl-2蛋白表达密切相关。结论Survivin在食管癌组织中表达上调,通过抑制细胞凋亡,在食管癌的发生中起到重要作用;凋亡相关基因bcl-2的上调与Survivin的表达可能在食管癌变中起协同作用。 相似文献
90.
N. Sinis H. O. Rennekampff M. Haerle H. -E. Schaller 《European journal of plastic surgery》2006,28(8):507-512
Intraoperative and postoperative free flap monitoring by means of oxygen tension measurement was carried out in 11 patients. We used an invasive flexible microcatheter that allowed for measurement of oxygen tension in all types of free flaps. Two cases of the measured flaps were buried free flaps which do not allow monitoring by clinical assessment. All flaps monitored in this study survived. One case of displacement of the microcatheter occurred. In one patient, the tissue pO2 monitor successfully detected early vascular thrombosis with subsequent reoperation and salvage of the free flap. 相似文献