全文获取类型
收费全文 | 128865篇 |
免费 | 11253篇 |
国内免费 | 6629篇 |
专业分类
耳鼻咽喉 | 1225篇 |
儿科学 | 1969篇 |
妇产科学 | 2931篇 |
基础医学 | 13472篇 |
口腔科学 | 2684篇 |
临床医学 | 15980篇 |
内科学 | 20161篇 |
皮肤病学 | 1590篇 |
神经病学 | 6396篇 |
特种医学 | 4195篇 |
外国民族医学 | 40篇 |
外科学 | 13339篇 |
综合类 | 19310篇 |
现状与发展 | 20篇 |
一般理论 | 18篇 |
预防医学 | 9434篇 |
眼科学 | 3446篇 |
药学 | 13461篇 |
115篇 | |
中国医学 | 6539篇 |
肿瘤学 | 10422篇 |
出版年
2024年 | 347篇 |
2023年 | 1716篇 |
2022年 | 4017篇 |
2021年 | 5457篇 |
2020年 | 4055篇 |
2019年 | 3680篇 |
2018年 | 3941篇 |
2017年 | 3705篇 |
2016年 | 3308篇 |
2015年 | 5236篇 |
2014年 | 6735篇 |
2013年 | 6947篇 |
2012年 | 10129篇 |
2011年 | 10882篇 |
2010年 | 7482篇 |
2009年 | 6151篇 |
2008年 | 7784篇 |
2007年 | 7726篇 |
2006年 | 7318篇 |
2005年 | 6691篇 |
2004年 | 4844篇 |
2003年 | 4403篇 |
2002年 | 3650篇 |
2001年 | 3092篇 |
2000年 | 2846篇 |
1999年 | 2643篇 |
1998年 | 1311篇 |
1997年 | 1220篇 |
1996年 | 986篇 |
1995年 | 948篇 |
1994年 | 885篇 |
1993年 | 504篇 |
1992年 | 890篇 |
1991年 | 801篇 |
1990年 | 668篇 |
1989年 | 569篇 |
1988年 | 525篇 |
1987年 | 450篇 |
1986年 | 357篇 |
1985年 | 284篇 |
1984年 | 184篇 |
1983年 | 167篇 |
1982年 | 95篇 |
1981年 | 93篇 |
1979年 | 140篇 |
1978年 | 111篇 |
1977年 | 83篇 |
1974年 | 94篇 |
1973年 | 72篇 |
1972年 | 87篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
本文对SOD的紫外分光光度法测定进行了实用性研究。结果表明,本文方法具有用血量少,重现性好,快速、灵敏,试剂廉价等优点。西宁地区与平原地区人群的比较测定显示,前者SOD活性明显高于后者(P<0.01)。 相似文献
92.
Cytoskeletal perturbations have been associated with exposures to a variety of toxic agents as well as a number of human pathological conditions. We have observed dramatic alterations in the organization of microtubules (MT), a major component of the cytoskeleton, in 3T3 cells exposed to Ni2+. Severe perinuclear bundling and aggregation of MT occurred in both a time- and dose-dependent fashion, and this MT damage was reversible upon removal of Ni2+ from the culture media. To understand the mechanism of the Ni2(+)-induced MT change, we investigated the effect of Ni2+ (0.01 to 3.0 mM) on in vitro tubulin polymerization. Ni2+ at lower concentrations (0.01 to 1.0 mM) had little or no significant effect on the kinetics of MT polymerization. In contrast, in the presence of 1.5 to 2.0 mM Ni2+, a significant promoting effect on both the rate and the final extent of polymerization was observed. However, at Ni2+ concentrations higher than 2.0 mM, such stimulatory effect on the rate and the final extent of tubulin polymerization declined. Furthermore, the promoting effects of Ni2+ on MT polymerization were accompanied by a significant decrease in the lag period. Electron microscopic examination of samples of the polymerization product showed that MT, polymerized in the presence of 2.0 mM Ni2+, appeared more numerous and shorter (1.10 +/- 1.02 microns) than those of control (3.81 +/- 2.29 microns; p less than 0.005). This was probably a direct result of an increase in the number of initiation centers in the presence of Ni2+ as a consequence of the decreased critical concentration (7%, p less than 0.05) necessary for polymerization to occur. Our results suggest that Ni2+ may exert its toxic effect on MT in cultured cells by altering the normal kinetics of MT polymerization. 相似文献
93.
刺激视上核对大鼠痛阈及电针镇痛的影响 总被引:2,自引:1,他引:1
以钾离子透引起的大鼠甩尾反应为痛指标,观察了电和化学刺激视上核(SON)对大鼠痛阈(PT)和电针(EA)镇痛的影响。电刺激SON后,PT明显高于假刺激组(P<0.05~0.001),电刺激SON后电针足三里,镇痛效应明显提高,并有明显的量效关系。电刺激SON的近旁部位(0.5—1mm)对PT及电针镇痛无明显影响。SON内注射L-谷氨酸(L-Glu)后痛阈和电针镇痛效应都明显对照组,也有明显的量效关 相似文献
94.
95.
Role of endothelin in the pathogenesis of hypertension in spontaneously hypertensive and 2 kidneys 1 clip rats. 总被引:1,自引:0,他引:1
The plasma endothelin (ET) level in spontaneously hypertensive rats (SHR) and 2K1C hypertension animal models and its vasoconstrictive effect on renal and tail arteries were studied. The results demonstrated that there was no difference in plasma ET level between the hypertensive groups SHR, 2K1C, normotensive control groups Wistar Kyot (WKY) and Sprague Dawley (SD), while the vasoconstrictive effect of ET in SHR was more dominant than in WKY. The EC50 of the renal and tail arteries in SHR (0.8912 +/- 0.1662 x 10(-8) M, 0.6103 +/- 0.0878 x 10(-8) M) was apparently lower than that in WKY (1.77 +/- 0.2991 x 10(-8) M, 1.2267 +/- 0.2502 x 10(-8) M, P less than 0.05), but no difference was found in 2K1C and SD rats. The four groups of animals exhibited no difference of such effects as response to norepine-phrine (NA). The findings suggested that the increased arteriole sensitivity to ET be an important factor in the pathogenesis of hypertension in SHR.
相似文献
96.
A Coagulation Factor IX-Deficient Mouse Model for Human Hemophilia B 总被引:25,自引:10,他引:15
Lin Hui-Feng; Maeda Nobuyo; Smithies Oliver; Straight David L.; Stafford Darrel W. 《Blood》1997,90(10):3962-3966
97.
核酸原位杂交程序中探针和靶基因的加热变性和杂交为整个程序中最重要的环节,目前国内外最常用的方法是在切片上滴加DNA探针溶液后用盖玻片复盖组织,并加胶泥或其他封固剂封闭玻片四周,变性杂交后需拆除盖玻片,这一操作过程易损坏组织切片或出现干片、脱片。作者针对上述情况,对传统的核酸原位杂交方法中的部分程序加以改良,采用不加盖玻片直接在蒸汽中变性方法,经多次实验证明此方法稳定、可靠、简便,结果满意。 相似文献
98.
本研究主要对El Tor型霍乱弧菌(Vibrio cholerae biotvpe eltor,EVC)L型的某些生物学特性如生化反应、抗生素敏感性及超微结构等进行了探讨.研究发现EVC不稳定L型的生化性状与EVC流行株的非常相似,而稳定L型则变化很大.抗生素敏感性试验显示EVC稳定L型对某些作用于细胞壁的抗生素的敏感性减弱,而对大多数作用于蛋白质合成的抗生素的敏感性增强.与流行株相比,EVC稳定L型和不稳定L型的超微结构的改变很明显.此外,本文还讨论了产生这些改变的可能机制. 相似文献
99.
临床输液监控系统的设计 总被引:5,自引:0,他引:5
本文针对临床输液过程中出现的漏、停、输液速度改变等各种问题,讨论了一由单台微机和多个单片机通讯实现的多床输液自动监控、自动反应、自动报答系统的可行性,并给出了主要部分的硬件、软件设计方法。 相似文献
100.
Propionic acidemia is a rare hereditary disease which is an autosomal recessive disorder. Defect of propionyl CoA carboxylase results in abnormal accumulation of propionate and its metabolites which interfere the pathway of glycine cleavage and the urea cycle. This organic acidemia is characterized by a wide spectrum of clinical and biochemical findings, including recurrent vomiting, difficult feeding, lethargy, hypotonia, metabolic ketoacidosis, hyperglycinemia and hyperammonemia during the acute episodes. We present a male newborn infant who sustained this disorder and was managed successfully with blood exchange transfusion, peritoneal dialysis, supplemented with sodium benzoate and sodium bicarbonate therapy. Urine gas chromatography disclosed significant elevation of propionate and its metabolites which subsided 2 days after peritoneal dialysis. Special designed formula was then given with restriction of protein intake and supplement with sodium benzoate and sodium carbonate. Prenatal genetic counseling is necessary in further pregnancy. Diagnosis can be obtained when propionyl CoA carboxylase activity is low in cultured amniotic fluid cells or chorion villi sample or when there is abnormally high methylcitrate level in amniotic fluid. 相似文献