全文获取类型
收费全文 | 25094篇 |
免费 | 2248篇 |
国内免费 | 2208篇 |
专业分类
耳鼻咽喉 | 170篇 |
儿科学 | 248篇 |
妇产科学 | 231篇 |
基础医学 | 2943篇 |
口腔科学 | 390篇 |
临床医学 | 3409篇 |
内科学 | 3595篇 |
皮肤病学 | 165篇 |
神经病学 | 1271篇 |
特种医学 | 861篇 |
外国民族医学 | 18篇 |
外科学 | 2893篇 |
综合类 | 4344篇 |
现状与发展 | 4篇 |
一般理论 | 1篇 |
预防医学 | 1752篇 |
眼科学 | 659篇 |
药学 | 2808篇 |
24篇 | |
中国医学 | 1382篇 |
肿瘤学 | 2382篇 |
出版年
2024年 | 109篇 |
2023年 | 407篇 |
2022年 | 1039篇 |
2021年 | 1214篇 |
2020年 | 955篇 |
2019年 | 833篇 |
2018年 | 859篇 |
2017年 | 746篇 |
2016年 | 777篇 |
2015年 | 1131篇 |
2014年 | 1388篇 |
2013年 | 1216篇 |
2012年 | 1697篇 |
2011年 | 1947篇 |
2010年 | 1245篇 |
2009年 | 991篇 |
2008年 | 1301篇 |
2007年 | 1421篇 |
2006年 | 1282篇 |
2005年 | 1325篇 |
2004年 | 811篇 |
2003年 | 913篇 |
2002年 | 688篇 |
2001年 | 577篇 |
2000年 | 642篇 |
1999年 | 747篇 |
1998年 | 466篇 |
1997年 | 466篇 |
1996年 | 332篇 |
1995年 | 312篇 |
1994年 | 319篇 |
1993年 | 180篇 |
1992年 | 217篇 |
1991年 | 187篇 |
1990年 | 161篇 |
1989年 | 155篇 |
1988年 | 134篇 |
1987年 | 103篇 |
1986年 | 76篇 |
1985年 | 82篇 |
1984年 | 29篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 19篇 |
1974年 | 1篇 |
1954年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
1.
Gerbils are much more sensitive to the hepatotoxic and lethal effects of CCl4 than rats as indicated by 48-hr LD50 values (0.08 vs 2.8 ml/kg). On the other hand, gerbils are refractory to chlordecone (CD) potentiation of CCl4 toxicity. To investigate the possible mechanism underlying the high sensitivity of gerbils to CCl4 lethality, the metabolism of CCl4 was studied in gerbils pretreated with dietary CD, phenobarbital (PB), or mirex (M) at 10, 225, and 10 ppm, respectively. The hepatic content of 14CCl4, the expiration of 14CCl4 and 14CCl4-derived 14CO2, and lipid peroxidation were measured and the results were compared with the previous data for rats. After the 15-day dietary pretreatment, male gerbils (60-80 g) received 14CCl4 (0.08 ml/kg; sp act 0.04 mCi/mmol) ip in corn oil and the radioactivity present in the expired air was collected for 6 hr. More than 80% of the parent compound as represented by the 14C-label in the toluene trap was expired in 6 hr regardless of the pretreatments. Expiration of 14CO2 measured during the 6 hr after 14CCl4 administration in control gerbils was 3.5-fold more than that in rats and was significantly increased in pretreated groups (M greater than PB greater than CD). PB and M pretreatments resulted in a significant increase of 14C-label bound to the nonlipid fraction of the liver as compared with CD-treated or control gerbils. The radiolabel present in the livers of control gerbils was 5-fold higher than that of rats. In vivo lipid peroxidation measured as diene conjugation in lipid extracts from the livers was lower in gerbils than in rats, and none of the pretreatments significantly affected lipid peroxidation. The serum alanine aminotransferase and aspartate aminotransferase were significantly elevated at 6 hr after CCl4 injection in all groups of gerbils. These data indicate that the more extensive metabolism of CCl4, as represented by 14CO2 formation and 14C-label bound to hepatic tissue, in gerbils as compared with rats, may partially explain the high sensitivity of gerbils to CCl4 toxicity. However, the enhanced metabolism of CCl4 found in CD-, PB-, or M-pretreated gerbils did not lead to amplified hepatotoxic and lethal effects of CCl4. The reason gerbils may be refractory to CD amplification of CCl4 injury might be associated with other factors yet to be investigated. 相似文献
2.
本研究采用先进的三维超声成像技术及多普勒技术对正常育龄妇女月经周期中心血管功能进行研究。结果:月经周期中HR、BP无变化;血清E2是周期性变化,排卵前达高峰。SV、CO、EF在排卵前期升高达峰值,显著高于月经期和黄体期;SVR排卵前期最低,而Ved、Ves无变化。Vmax、A、E在内源性E2高峰时明显加快,而E/A比值无明显变化。结果提示:月经周期中随内源性E2的周期性变化,心脏功能也发生周期性变化。E2高峰时,心输出量、心搏量和射血分数达最高。外周阻力最低,心脏内血流速度加快。 相似文献
3.
采用 TAD 方案治疗急性非淋巴细胞性白血病(ANLL)12例,年龄17~47岁。总有效率为66.7%,完全缓解率(CR)为41.7%。5例获 CR 的时间是26~66天,平均53天,较国内其它方案为快。CR 时间为2~9月,平均6.2月,较其它方案又较短。TAD 方案对心脏的毒性作用轻微。TAD 方案对5例获 CR 者,于诱导治疗第一疗程后,除1例外,骨髓中白血病细胞百分比下降均不明显;但于第二疗程后,白血病细胞全部减少到骨髓有核细胞总数的20%/以下,这种现象似可作为本方案预后的观察指标。 相似文献
4.
5.
6.
儿童阻塞性睡眠呼吸暂停低通气综合征的治疗 总被引:32,自引:0,他引:32
目的探讨儿童阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep apnea hypopnea syndrome,OSAHS)患儿的治疗方法和疗效观察。方法经多道睡眠监测(polysomnography,PSG)确诊的4~12岁OSAHS患儿59例:扁桃体切除和(或)经口内镜(内窥镜,下同)引导下腺样体刮除54例;选择长期正压通气治疗(continue positive airway pressure,CPAP)2例;保守治疗3例。采用儿童OSAHS生活质量调查表(quality of life for children with obstructive sleep apnea 18 items,OSA-18)对患儿进行治疗前后的随访。结果围手术期无术后出血、急性呼吸道梗阻发生。随访12~18个月,手术患儿无鼻咽闭锁、咽鼓管功能障碍、腺样体残留等并发症;OSA-18调查评分显示:治疗后76.3%(45例)的患儿生活质量总体指标,88.1%(52例)的患儿睡眠呼吸障碍,67.8%(40例)的患儿身体症状得到显著改善。长期CPAP治疗的有效治疗压力在5.6~7.8cm H2O左右。3例保守治疗者略有改善。结论手术切除引起上气道阻塞的肥大的扁桃体和(或)腺样体是儿童OSAHS有效的治疗手段之一,纤维鼻咽镜检查、头颅侧位X线摄片有助于手术适应证的确定。经口内镜引导下腺样体刮除术具有直视下操作,视野清晰,切除彻底,可避免损伤周围重要结构的特点。 相似文献
7.
LaVoie Edmond J.; Cai Zhen-Wei; Meschter Carol L.; Weyand Eric H. 《Carcinogenesis》1994,15(10):2131-2135
Fluoranthene (FA) is frequently among the more abundant componentsdetected in environmental mixtures of polycyclic aromatic hydrocarbons.Several methylated fluoranthenes, although less prevalent thanFA, have also been detected as environmental pollutants. WhileFA is inactive as a tumorigenic agent on mouse skin, it doesinduce lung and liver tumors in newborn mice. Among the fiveisomers of methylfluoranthene, only 2-methylfluoranthene (2-MeFA)and 3-methylfluoranthene (3-MeFA) are active as tumor initiatorson mouse skin. A comparative bioassay was performed to determinethe relative tumorigenic activity of FA, 2-MeFA and 3-MeFA innewborn CD-1 mice. All three compounds were assayed at dosesof 3.46 and 17.3 µmol. The bioassay was terminated whenmice were 1 year old. At a dose of 17.3 µmol, FA and 2-MeFAinduced a similar incidence of lung tumors (6596%) inboth male and female mice. However, tumor multiplicity in thelung was different between FA and 2-MeFA. At a dose of 17.3µmol, the multiplicity of lung tumors observed for miceadministered 2-MeFA ranged from 3.04 to 3.94 tumors per mouse.In contrast, animals treated with FA developed only an averageof 1.122.45 tumors per mouse. 3-MeFA did not induce astatistically significant incidence of lung tumors in eithermale or female mice. All three compounds when administered tonewborn mice did induce a significant incidence of liver tumorsamong male mice. The relative tumorigenic potency observed wasFA 5 相似文献
8.
Zhi-gang Wang Yi-dong Huang Ke-luo Cheng Xiao-bi Cai Zheng Wu Jian-dong Zhan 《第一军医大学学报》2004,24(3):345-6, 351
OBJECTIVE: To study how blood supply of the esophageal and gastric stumps influences the anastomotic healing after esophagogastrostomy in rabbits. METHODS: Twenty-seven New Zealand rabbits were randomly divided into 3 groups to receive esophagogastrostomy, followed by different procedures. Except for those in group I, all the rabbits were subjected to procedures of reducing the blood supply either of the esophageal or the gastric stump (group II and group III, respectively), followed by single-layer esophagogastric anastomoses using interrupted 5-0 polypropylene sutures. Ten days after operation, all the rats were killed and the anastomotic sites excised for measurement of the inner diameter, tensile strength, and hydroxyproline concentration. RESULTS: Healing of the esophagograstric anastomosis was obtained in all the rabbits but one with anastomotic leakage in group I and one with perforation of the gastric fundus in group III. The anastomotic inner diameters were similar in all the three groups, whereas the tensile strength and hydroxyproline concentration at the anastomoses decreased in group III in comparison with the other two groups (P<0.05) that had similar measurements (P>0.05). CONCLUSIONS: Extended length of the free esophageal stump does not significantly affect anastomotic healing as decrease of blood supply in the gastric stump. 相似文献
9.
10.
蔡生荣 《宁夏医科大学学报》1995,17(3):211-214
本文就宁夏医学院附属医院肿瘤外科1984~1994年6月收治的603例胃癌中的5例残胃癌患者,结合文献对其发病年龄,部位,发病率,生物学行为、临床表现、早期诊断以及残胃癌与胃大部切除术式的关系等进行了探讨,认为:1.以外科手术为主的综合治疗是残胃癌的治疗原则;2.定期随诊是早期发现残胃癌的关键,3.B-Ⅰ式吻合或Roux-en-Y式吻台取代B-Ⅱ式吻合,可避免十二指肠液返流入残胃,减缓残胃癌的发生。 相似文献