全文获取类型
收费全文 | 16806篇 |
免费 | 1476篇 |
国内免费 | 920篇 |
专业分类
耳鼻咽喉 | 153篇 |
儿科学 | 200篇 |
妇产科学 | 330篇 |
基础医学 | 2065篇 |
口腔科学 | 343篇 |
临床医学 | 2245篇 |
内科学 | 2652篇 |
皮肤病学 | 242篇 |
神经病学 | 873篇 |
特种医学 | 465篇 |
外国民族医学 | 7篇 |
外科学 | 1826篇 |
综合类 | 2432篇 |
现状与发展 | 1篇 |
一般理论 | 11篇 |
预防医学 | 951篇 |
眼科学 | 421篇 |
药学 | 1732篇 |
8篇 | |
中国医学 | 695篇 |
肿瘤学 | 1550篇 |
出版年
2024年 | 62篇 |
2023年 | 274篇 |
2022年 | 626篇 |
2021年 | 733篇 |
2020年 | 552篇 |
2019年 | 540篇 |
2018年 | 590篇 |
2017年 | 484篇 |
2016年 | 445篇 |
2015年 | 721篇 |
2014年 | 903篇 |
2013年 | 912篇 |
2012年 | 1302篇 |
2011年 | 1423篇 |
2010年 | 896篇 |
2009年 | 706篇 |
2008年 | 885篇 |
2007年 | 907篇 |
2006年 | 859篇 |
2005年 | 827篇 |
2004年 | 581篇 |
2003年 | 553篇 |
2002年 | 401篇 |
2001年 | 372篇 |
2000年 | 375篇 |
1999年 | 437篇 |
1998年 | 264篇 |
1997年 | 259篇 |
1996年 | 177篇 |
1995年 | 164篇 |
1994年 | 132篇 |
1993年 | 96篇 |
1992年 | 111篇 |
1991年 | 85篇 |
1990年 | 75篇 |
1989年 | 59篇 |
1988年 | 87篇 |
1987年 | 77篇 |
1986年 | 45篇 |
1985年 | 43篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 28篇 |
1978年 | 9篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1972年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
201.
Nm23 protein expression was analyzed by immunohistochemical staining using formalin-fixed, paraffin-embedded sections from 39 cases with osteosarcomas and compared with the histologic findings and early metastasis for the purpose of detecting nm23 expression in osteosarcoma and elucidating the clinical significance of its expression. Immunoreactivity of nm23 protein was detected in 48.7% of the total cases. There was no statistical difference between nm23 expression and early metastasis, but there was a trend for cases with nm23 expression to progress to early metastasis within 1 year after operation. The role of nm23 as a tumor metastasis suppressor in osteosarcomas appeared less prominent. 相似文献
202.
毛细管气相色谱法测定头孢噻利和普卢利沙星中7种有机溶剂残留量 总被引:8,自引:1,他引:8
目的 建立硫酸头孢噻利和普卢利沙星中正己烷、二氯甲烷、乙腈、三氯甲烷、二氧六环、甲苯和N,N-二甲基甲酰胺 7种有机溶剂残留量的测定方法。方法 采用毛细管气相色谱法 ,氢火焰离子化检测器(FID) ,以二甲基亚砜为溶剂 ,石英毛细管柱 OV- 170 1(15 m× 0 .5 3mm,1.0μm ) ;柱温 :4 0℃恒温 10 min,以30℃ / min的速率升温至 10 0℃恒温 2 5 min;载气 :高纯氮气 ;氢气 :70 ml/ min;不分流进样。结果 3批样品中 7种有机溶剂残留量均符合要求。方法平均回收率 99.6 %~ 10 0 .4 % (RSD≤ 1.9% )。结论 本法简便灵敏、准确、重复性好 ,能较好地进行硫酸头孢噻利和普卢利沙星中有机残留量的测定。 相似文献
203.
麦草粉与绿茶对亚硝化鱼露致微核率增高的抑制作用 总被引:2,自引:0,他引:2
应用小鼠骨髓嗜多染经细胞(PCE)微核试验方法,研究麦草粉与绿茶对胃癌高发区鱼露径亚硝化后致突变的抑制作用,结果表明:20%麦草粉,10%绿茶可降低亚硝化鱼露所致的小鼠微核率增高的作用(P〈0.01),将按成分换算后相当于0.02%VC的20%麦草粉干预组和0.002%VC的10%绿茶干预组与0.1%VC干预对照组比较,微核出现率没有显著差异(P〉0.05)。提示麦草粉,绿茶的抑制作用尚与VC外的 相似文献
204.
中国发生艾滋病毒感染流行的危险因素 总被引:26,自引:1,他引:26
1985年,我国报告的首例艾滋病(AIDS)病人是外国旅游者,到1989年,在云南西南边境地区吸毒者中首次发现艾滋病病毒(HIV)感染的流行。1994年起,在我国其他地区报告的HIV感染者明显增加,截至1997年10月,我国共报告HIV感染者8303... 相似文献
205.
颅底恶性肿瘤切除术后组织缺损一期修复的探讨──附18例报告 总被引:2,自引:0,他引:2
目的:为解决颅底恶性肿瘤的广泛切除或根治性切除术后所致的颅底骨与软组织缺损,预防此缺损所致的颅内感染,脑脊液漏等并发症。方法:在术中应用了斜方肌下部岛状肌皮瓣,胸大肌下部岛状肌皮瓣,颞肌复合组织瓣等各种修复方法分别对18例患者进行了一期修复。结果:修复成功率73.2%(13例),术后并发症27.8%(5例).结论:根据组织缺损的不同大小、范围、程度、部位和不同的手术入路来选择不同的修复方法,关系到手术成败。 相似文献
206.
采用水迷宫法、穿梭箱法、避暗法、跳台法观察了生命1号对小鼠学习、记忆、巩固的影响。灌胃给生命1号可改善东莨菪碱、樟柳碱致小鼠记忆获得障碍。生命1号能明显提高单核细胞吞噬功能,显著增加小鼠血清溶血素的含量,促进T淋巴细胞的转化。除此之外,还能明显地增加阳虚大鼠股骨的重量、长度、直径及皮质厚度;提高血清钙、磷水平;降低血清碱性磷酸酶的含量,具有促进骨骼生长的作用。 相似文献
207.
目的:探讨中药对人工晶体状体植入术后虹膜睫状体炎的治疗效果。方法:对24例(29只眼)人工晶状体植入术后虹膜睫状体炎患者,在后马托品或托品酰胺滴眼散瞳的情况下,用口服血栓通胶囊和凉血清热泻肝汤加减进行了治疗和为期3个月 ̄12个月的随访观察。结果:治疗时间最短为5天,最长者21天,平均11天。治愈22例27只眼(93.10%),未见复发,视力达0.6以上。好转2例2只眼(6.9%)。结论:在应用散瞳 相似文献
208.
Inhibition of growth and induction of apoptosis in human cancer cell lines by tea polyphenols 总被引:47,自引:7,他引:47
In order to study the biological activities of tea preparations and
purified tea polyphenols, their growth inhibitory effects were investigated
using four human cancer cell lines. Growth inhibition was measured by
[3H]thymidine incorporation after 48 h of treatment. The green tea
catechins (-)-epigallocatechin-3-gallate (EGCG) and (-)- epigallocatechin
(EGC) displayed strong growth inhibitory effects against lung tumor cell
lines H661 and H1299, with estimated IC50 values of 22 microM, but were
less effective against lung cancer cell line H441 and colon cancer cell
line HT-29 with IC50 values 2- to 3- fold higher.
(-)-Epicatechin-3-gallate, had lower activities, and (-)- epicatechin was
even less effective. Preparations of green tea polyphenols and theaflavins
had higher activities than extracts of green tea and decaffeinated green
tea. The results suggest that the growth inhibitory activity of tea
extracts is caused by the activities of different tea polyphenols. Exposure
of H661 cells to 30 microM EGCG, EGC or theaflavins for 24 h led to the
induction of apoptosis as determined by an annexin V apoptosis assay,
showing apoptosis indices of 23, 26 and 8%, respectively; with 100 microM
of these compounds, the apoptosis indices were 82, 76 and 78%,
respectively. Incubation of H661 cells with EGCG also induced a
dose-dependent formation of H2O2. Addition of H2O2 to H661 cells caused
apoptosis in a manner similar to that caused by EGCG. The EGCG-induced
apoptosis in H661 cells was completely inhibited by exogenously added
catalase (50 units/ml). These results suggest that tea polyphenol-induced
production of H2O2 may mediate apoptosis and that this may contribute to
the growth inhibitory activities of tea polyphenols in vitro.
相似文献
209.
Characterization of xenobiotic-metabolizing enzymes and nitrosamine metabolism in the human esophagus 总被引:5,自引:2,他引:5
Smith TJ; Liao A; Wang LD; Yang GY; Starcic S; Philbert MA; Yang CS 《Carcinogenesis》1998,19(4):667-672
Esophageal cancer has been associated with tobacco smoking, and
nitrosamines are possible causative agents for this cancer. The present
study investigated the metabolism of the tobacco carcinogens N'-
nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone
(NNK), and N-nitrosodimethylamine (NDMA), as well as the presence of
xenobiotic-metabolizing enzymes in human esophageal tissues from
individuals in the United States and Huixian, Henan Province, China (a
high-risk area for esophageal cancer). All esophageal microsomal samples
activated NNN and the metabolic rate was 2-fold higher in the esophageal
samples from China than the USA. All microsomal samples activated NDMA.
However, most of the microsomal samples did not activate NNK.
Troleandomycin (an inhibitor of cytochrome P450 3A) decreased the formation
of NNN-derived keto acid by 20-26% in the esophageal microsomes. The
activities for NADPH: cytochrome c reductase, ethoxycoumarin O-deethylase,
NAD(P)H: quinone oxidoreductase and glutathione S-transferase were present
in the esophageal samples. Coumarin 7-hydroxylase (a representative
activity for P450 2A6) activity was not detected in the esophageal
microsomal samples. The activities for nitrosamine metabolism and
xenobiotic- metabolizing enzymes were decreased (by 30-50%) in the squamous
cell carcinomas compared with their corresponding non-cancerous mucosa. The
presence of activation and detoxification enzymes in the esophagus may play
an important role in determining the susceptibility of the esophagus to the
carcinogenic effect of nitrosamines. Our results suggest that P450s 3A4 and
2E1 are involved in the activation of NNN and NDMA, respectively, in the
human esophagus.
相似文献
210.
Early stage nasopharyngeal carcinoma: radiotherapy dose and time factors in tumor control 总被引:1,自引:0,他引:1
Chang JT; See LC; Liao CT; Chen LH; Leung WM; Chen SW; Chen WC 《Japanese journal of clinical oncology》1998,28(3):207-213
OBJECTIVE: To evaluate radiotherapy dose and length of treatment in the
control of early stage nasopharyngeal carcinoma (NPC) treated with a
combination of external radiotherapy and brachytherapy, MATERIALS &
METHODS: We reviewed the records of 133 patients with early stage
nasopharyngeal carcinoma (stage I or II, AJC/UICC staging system) who
received definitive radiotherapy in Chang Gung Memorial Hospital from 1979
to 1991. The median follow-up time was 7.1 years with a minimum of 2 years.
All patients were treated with megavoltage external radiotherapy to the
nasopharynx area (63-72 Gy) followed by high dose rate intracavitary
brachytherapy (5-16.5 Gy in one to three fractions, spaced 1-2 weeks
apart). The median total dose and time of irradiation was 75 Gy (69.8-81.4
Gy) and 11.6 weeks (7.8-20 weeks) respectively. Survival analysis was used
to examine the effect of several variables on prognosis. RESULTS: The
5-year rates were 86.4% for local control, 84.7% for disease free survival,
88.5% for actuarial survival and 84.2% for overall survival. The treatment
group (combination of time and dose of irradiation) was the most important
prognostic factor according to Cox's proportional hazard model. Patients
receiving radiation at a total dose of < or = 75 Gy completed in < 12
weeks showed the best prognosis. CONCLUSION: Treatment time and total
treatment dose are both important factors in treating early stage NPC.
Decreasing the total radiation time to < 12 weeks and not exceeding a
radiation dose of 75 Gy gave the best results.
相似文献