全文获取类型
收费全文 | 164549篇 |
免费 | 15860篇 |
国内免费 | 11093篇 |
专业分类
耳鼻咽喉 | 1735篇 |
儿科学 | 2239篇 |
妇产科学 | 1376篇 |
基础医学 | 15081篇 |
口腔科学 | 2868篇 |
临床医学 | 20136篇 |
内科学 | 20380篇 |
皮肤病学 | 1928篇 |
神经病学 | 6535篇 |
特种医学 | 6191篇 |
外国民族医学 | 68篇 |
外科学 | 17000篇 |
综合类 | 35598篇 |
现状与发展 | 49篇 |
一般理论 | 10篇 |
预防医学 | 14046篇 |
眼科学 | 3652篇 |
药学 | 17481篇 |
195篇 | |
中国医学 | 12647篇 |
肿瘤学 | 12287篇 |
出版年
2024年 | 631篇 |
2023年 | 2313篇 |
2022年 | 5974篇 |
2021年 | 7749篇 |
2020年 | 6232篇 |
2019年 | 4724篇 |
2018年 | 5113篇 |
2017年 | 5203篇 |
2016年 | 4909篇 |
2015年 | 7800篇 |
2014年 | 9505篇 |
2013年 | 9908篇 |
2012年 | 14304篇 |
2011年 | 15348篇 |
2010年 | 11604篇 |
2009年 | 9692篇 |
2008年 | 10866篇 |
2007年 | 10398篇 |
2006年 | 9749篇 |
2005年 | 8261篇 |
2004年 | 5854篇 |
2003年 | 5503篇 |
2002年 | 4533篇 |
2001年 | 3431篇 |
2000年 | 2641篇 |
1999年 | 2019篇 |
1998年 | 1164篇 |
1997年 | 1104篇 |
1996年 | 868篇 |
1995年 | 785篇 |
1994年 | 601篇 |
1993年 | 377篇 |
1992年 | 401篇 |
1991年 | 324篇 |
1990年 | 296篇 |
1989年 | 226篇 |
1988年 | 196篇 |
1987年 | 193篇 |
1986年 | 143篇 |
1985年 | 110篇 |
1984年 | 57篇 |
1983年 | 44篇 |
1982年 | 33篇 |
1981年 | 38篇 |
1980年 | 20篇 |
1979年 | 42篇 |
1977年 | 19篇 |
1976年 | 17篇 |
1974年 | 22篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
目的 为构建生物人工肝进行肝细胞的准备。方法 采用胶原酶半原位灌流法分离单个乳猪肝细胞,并对其活力及单层和聚集培养后的白蛋白、尿素合成功能进行检测。结果 采用本方法从每头乳猪中分离到的单个肝细胞数为(3.1±1.5)×10~(10),活性超过95%。在加入激素和生长因子的培养基中单层培养时,肝细胞功能良好,可维持2周左右。而在未加入激素和生长因子的培养中肝细胞虽能存活1周,但功能于24h后即丧失。球形聚集培养可实现肝细胞的大量培养,且生物学活性较单层培养显著提高。结论 采用胶原酶半原位灌注法所得单个乳猪肝细胞基本能满足构建生物人工肝对肝细胞数量的要求。聚集培养接种密度大,细胞生物学活性高,可用于构建生物人工肝。 相似文献
22.
A randomly selected sample of 662 12-year-old Hong Kong children, 529 of whom were Southern Chinese and 133 non-Chinese, was clinically examined for dental caries. The DMFT values were 2.76 and 1.66 for the Chinese and non-Chinese children, respectively. The D component for the Chinese children was 2.12, while for the non-Chinese children it was only 0.45. Approximately 24.0% of the Chinese children had attended the dentist because they were in pain. Only 3.8% of the Chinese children had sought orthodontic or preventive treatment, compared with 24.0% of the non-Chinese children. Although these findings indicate the caries experience to be well below the FDI/WHO global goal for the year 2000, there is a great need to increase the level of dental awareness among Chinese children. 相似文献
23.
Infusions made from 15 Chinese, 11 Ceylon/Indian and 6 herb teas (1 g/100 ml deionized water at 85 degrees C) were analyzed for F, P, Ca, Al, Mg, Mn and Zn. Chinese teas continued to release F throughout the first hour of infusion, whereas release of F from Ceylon/Indian teas was essentially completed after 5 minutes. After a 15-minute infusion, the mean F concentration in Chinese teas was 1.73 ppm, and in Ceylon/Indian teas it was 1.24 ppm. Herb teas contained a negligible amount of F (0.02-0.05 ppm). Phosphorus and Mg were the most abundant of the other elements with an average of 12.5 and 9.1 ppm, respectively. A high correlation (r = 0.81) was found between the released F and Al. The total F content in tea leaves ranged from 82 to 371 ppm. The addition of milk to tea infusions did not appreciably reduce the F concentration. The estimated daily F intake from tea infusion made with fluoridated water at 0.7 ppm is 1.05 mg. 相似文献
24.
动态增强MR灌注成像在脑胶质瘤诊断中的价值 总被引:1,自引:0,他引:1
目的 探讨动态增强T2 WMR灌注成像在脑胶质瘤术前分级预测及鉴别诊断中的价值。资料与方法 有病理或追踪结果的 4 8例脑病变患者 ,其中胶质瘤 2 5例 (高、低级别胶质瘤分别为 16例和 9例 ) ,非胶质瘤病变 2 3例。全部病例均行常规T1WI、T2 WI和EPI SE序列动态增强MR灌注成像。计算每个病灶的最大相对脑血容量 (rCBV)比值 (病灶最大rCBV/对侧正常脑白质rCBV)。分析胶质瘤的最大rCBV比值与其组织学级别的关系 ,并比较胶质瘤与非胶质瘤的灌注异常及常规MRI强化表现。结果 高级别胶质瘤 ( 16例 )的最大rCBV比值为4 .6 0± 1.98( 2 .5 5~ 9.2 2 ) ,低级别胶质瘤 ( 9例 )的最大rCBV比值为 1.86± 1.5 2 ( 0 .85~ 5 .72 ) ,经t检验 ,两组之间有显著统计学差异 (P <0 .0 1)。脑膜瘤、转移瘤、血管母细胞瘤、淋巴瘤均显示有局部高灌注 ,最大rCBV比值为5 .35± 2 .39( 3.15~ 12 .39) ,而有强化表现的脑梗死、脑炎性灶及放射性脑损伤表现为低、等灌注 ,最大rCBV比值为1.2 7± 0 .36 ( 0 .85~ 1.72 )。结论 MR灌注成像在胶质瘤的术前影像学分级预测上有重要价值 ,在脑胶质瘤的某些鉴别诊断上亦具有一定的参考价值 相似文献
25.
26.
Foley尿管气囊压迫治疗骶前静脉丛大出血的评价(附6例报告) 总被引:5,自引:0,他引:5
目的:评价直肠癌根治术中用Foley尿管气囊压迫治疗骶前静脉丛大出血(MPVP)的临床价值。方法:分析1995~2005年用Foley尿管气囊压迫治疗骶前静脉丛大出血6例的临床资料。结果:6例骶前大出血中全部用Foley尿管气囊压迫控制出血,术中出血量为800~1700mL,Foley尿管于术后4d拔除3例,5d1例,6d2例,均无再出血,会阴切口均一期愈合。结论:Foley尿管气囊压迫治疗骶前静脉丛大出血是一种简单安全有效的治疗方法。 相似文献
27.
Z-Y Sun J Wei L Xie Y Shen S-Z Liu G-Z Ju J-P Shi Y-Q Yu X Zhang Q Xu G P Hemmings 《European psychiatry》2004,19(6):354-357
The present study was designed to detect three single nucleotide polymorphisms (SNPs) located on 22q11 that was thought as being of particularly importance for genetic research into schizophrenia. We recruited a total of 176 Chinese family trios of Han descent, consisting of mothers, fathers and affected offspring with schizophrenia for the genetic analysis. The transmission disequilibrium test (TDT) showed that of three SNPs, rs10314 in the 3'-untranslated region of the CLDN5 locus was associated with schizophrenia (chi(2) = 4.75, P = 0.029). The other two SNPs, rs1548359 present in the CDC45L locus centromeric of rs10314 and rs739371 in the 5'-flanking region of the CLDN5 locus, did not show such an association. The global chi-square (chi(2)) test showed that the 3-SNP haplotype system was not associated with schizophrenia although the 1-df test for individual haplotypes showed that the rs1548359(C)-rs10314(G)-rs739371(C) haplotype was excessively non-transmitted (chi(2) = 5.32, P = 0.02). Because the claudin proteins are a major component for barrier-forming tight junctions that could play a crucial role in response to changing natural, physiological and pathological conditions, the CLDN5 association with schizophrenia may be an important clue leading to look into a meeting point of genetic and environmental factors. 相似文献
28.
29.
E P Wei R Kukreja H A Kontos 《Stroke; a journal of cerebral circulation》1992,23(11):1623-8; discussion 1628-9
BACKGROUND AND PURPOSE: We investigated the chemical identity of the endothelium-derived relaxing factor generated by acetylcholine in cerebral microvessels by studying the effects and mechanism of action of inhibitors of nitric oxide synthesis from arginine on the vasodilation and endothelium-derived relaxing factor production induced by topical application of acetylcholine in cerebral arterioles. METHODS: We determined cerebral arteriolar dilation and endothelium-derived relaxing factor production by bioassay in anesthetized cats equipped with cranial windows during superfusion of 10(-7) M acetylcholine before and after administration of either NG-monomethyl L-arginine or NG-nitro-L-arginine, two inhibitors of nitric oxide synthesis. RESULTS: NG-Nitro-L-arginine abolished the vasodilation from acetylcholine and eliminated the production of endothelium-derived relaxing factor in the bioassay experiments. NG-Monomethyl L-arginine had no effect on the response to acetylcholine in the absence of pretreatment. However, after pretreatment with the detergent sodium dodecyl sulfate to increase cell membrane permeability, the inhibitor had effects identical to those of NG-nitro-L-arginine. L-Arginine reversed the effects of the inhibitors of nitric oxide synthesis. Neither inhibitor affected baseline vascular caliber, nor did they generate a vasoconstrictor agent in the bioassay experiments. The two inhibitors of nitric oxide synthesis did not affect the response to nitroprusside or adenosine, showing that the effect on responses to acetylcholine was specific. Also, the blockade of the response to acetylcholine induced by the inhibitors of nitric oxide synthesis was unaffected by treatment with superoxide dismutase and catalase, showing that the effect was not mediated by oxygen radicals. CONCLUSION: The endothelium-derived relaxing factor generated by acetylcholine in cerebral arterioles of cats is either nitric oxide or a nitric oxide-containing substance. The effect of these inhibitors on the response to acetylcholine is mediated by inhibition of the synthesis of nitric oxide. There is no involvement of radicals, and no vasoconstrictor agent is generated. 相似文献
30.