全文获取类型
收费全文 | 10179篇 |
免费 | 419篇 |
国内免费 | 197篇 |
专业分类
耳鼻咽喉 | 50篇 |
儿科学 | 205篇 |
妇产科学 | 385篇 |
基础医学 | 1460篇 |
口腔科学 | 62篇 |
临床医学 | 632篇 |
内科学 | 1560篇 |
皮肤病学 | 289篇 |
神经病学 | 1203篇 |
特种医学 | 266篇 |
外科学 | 821篇 |
综合类 | 1078篇 |
预防医学 | 1270篇 |
眼科学 | 32篇 |
药学 | 903篇 |
2篇 | |
中国医学 | 297篇 |
肿瘤学 | 280篇 |
出版年
2023年 | 129篇 |
2022年 | 238篇 |
2021年 | 389篇 |
2020年 | 336篇 |
2019年 | 272篇 |
2018年 | 219篇 |
2017年 | 261篇 |
2016年 | 255篇 |
2015年 | 223篇 |
2014年 | 452篇 |
2013年 | 607篇 |
2012年 | 420篇 |
2011年 | 574篇 |
2010年 | 435篇 |
2009年 | 477篇 |
2008年 | 526篇 |
2007年 | 514篇 |
2006年 | 427篇 |
2005年 | 401篇 |
2004年 | 309篇 |
2003年 | 295篇 |
2002年 | 278篇 |
2001年 | 202篇 |
2000年 | 208篇 |
1999年 | 187篇 |
1998年 | 148篇 |
1997年 | 131篇 |
1996年 | 102篇 |
1995年 | 126篇 |
1994年 | 129篇 |
1993年 | 116篇 |
1992年 | 109篇 |
1991年 | 115篇 |
1990年 | 93篇 |
1989年 | 77篇 |
1988年 | 72篇 |
1987年 | 76篇 |
1986年 | 87篇 |
1985年 | 93篇 |
1984年 | 112篇 |
1983年 | 65篇 |
1982年 | 60篇 |
1981年 | 75篇 |
1980年 | 65篇 |
1979年 | 62篇 |
1978年 | 60篇 |
1977年 | 41篇 |
1976年 | 33篇 |
1975年 | 31篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Solveig B. Larsen Aleksander Giwercman Marcello Spanò Jens P. Bonde The ASCLEPIOS Study Group 《Reproductive toxicology (Elmsford, N.Y.)》1998,12(6):391-589
It was hypothesized that occupational exposure to pesticides during a spraying season causes changes in semen quality that might be detected in a longitudinal study. We analyzed the within-person changes in semen quality and reproductive hormones across a spraying season in groups of farmers using and not using pesticides. A total of 248 men collected two semen samples (participation rate: 32%). The median sperm concentration declined significantly from the first to the second sample in both groups, but there was no statistical difference in the decline between the two groups, unadjusted or adjusted. Only minor changes were found in sperm morphology, vitality, motility, sperm chromatin denaturation (SCSA), and reproductive hormones, and the differences in changes between the two groups were nonsignificant, or, in the opposite direction to the expected. There was no relation between the changes in sperm parameters in relation to pesticide exposure variables. In conclusion, use of pesticides by Danish farmers is not a likely cause of short-term effects on semen quality and reproductive hormones. 相似文献
22.
Charles J. Meliska Andrzej Bartke Jimmy L. Vandergriff Robert A. Jensen 《Pharmacology, biochemistry, and behavior》1995,50(4):563-570
Transgenic mice overexpressing the phosphoenolpyruvate carboxykinase/bovine growth hormone (PEPCK/ bGH) hybrid gene and normal (nontransgenic) littermate controls (10 males + 10 females/group) were given access to tapwater and an ascending series of concentrations of ethanol (1.0–22.0%), then a similar ascending series of concentrations of nicotine (1.0–40.0 μg/ml), in a two-bottle choice test. Male transgenic mice consumed more and exhibited greater preferences for ethanol and nicotine than control males; transgenic females consumed less and showed lower preferences for ethanol, but not nicotine, than control females. These results suggest that chronic exposure to high levels of bGH may modulate the rewarding effects of ethanol and nicotine in mice in a gender-specific fashion. 相似文献
23.
超声引导下注射皮质类固醇治疗狭窄性腱鞘炎 总被引:1,自引:0,他引:1
目的 探讨超声引导下注射皮质类固醇治疗狭窄性腱鞘炎的方法及效果。方法 38例狭窄性腱鞘炎患者,按药物注射方法的不同随机分成2组。治疗组(21例)在10-MHz超声引导下向腱鞘内腱周间隙内穿刺注射醋酸强的松龙0.6 ml,对照组(17例)采用闭合穿刺法注射等量药物。注射前及随访时(注射后3周)测定疼痛强度视觉类比评分(Visual analogue score,VAS)。结果 随访时疼痛消失率治疗组为81%、对照组为53%,VAS下降值治疗组为[(6.8±1.9)x±s,下同]对照组为(5.1±3.0)。结论超声引导下将针尖穿刺于腱鞘内腱周间隙的操作简单、准确并可实时观察药物的分布,是治疗狭窄性腱鞘炎的较好方法。 相似文献
24.
Ikuo Konishi 《Medical Electron Microscopy》1994,27(3-4):271-274
The developmental relationship between granulosa and stromal cells in the fetal ovary was reviewed. The proliferation and
expression of basic fibroblast growth factor (bFGF) and luteinizing hormone receptor (LHR) of both the granulosa and theca
cells was examined in the adult ovary. Ovarian granulosa cell tumors were then studied under light and electron microscopy
and for immunohistochemical expression of bFGF and LHR. In the follicular development of the adult ovary, bFGF expression
in the granulosa cells was correlated with theca cell proliferation. In ovarian granulosa cell tumors, estrogen-producing
tumors showed a stratified or microfollicular pattern being accompanied by theca cells which had ultrastructural features
of steroid-production, and these tumor cells exhibited immunoreactivity for bFGF. In contrast, tumors with no apparent hormone-production
showed a solid or gyriform pattern without admixture of theca cells, and were negative for bFGF. LHR was expressed in both
types of tumor. Accordingly, bFGF may play an important role in association with the theca cell component in granulosa cell
tumors. 相似文献
25.
This paper reviews the literature on colorectal cancer from a sex and gender-based perspective. Colorectal cancer is a major cause of death in the developed world, with rates increasing in developing countries. Although described by some writers as an ‘equal opportunity’ disease, it presents more risk to men than women. Both biological, or sex-linked factors, and gender-linked factors play a part in the aetiology of the disease, while gender differences in the use of screening and treatment also help shape the mortality gap between women and men for this condition. Without an appreciation of the part played by sex and gender in the risk of colorectal cancer, and without a gender-sensitive approach to screening in particular, it is possible that the mortality gap between men and women for this condition will widen in the future. 相似文献
26.
27.
Nicotine discrimination and self-administration in humans as a function of smoking status 总被引:2,自引:2,他引:0
Nicotine’s discriminative stimulus effects may be critical to understanding reinforcement of tobacco smoking. It is not known
whether regular nicotine exposure produces tolerance or sensitivity to these effects. In this study, male and female smokers
(n = 11) and never-smokers (n = 10) were trained to discriminate 20 μg/kg nicotine by nasal spray from placebo (0) on day 1. On day 2, both groups were
tested on generalization of this discrimination across intermittent presentations of 0, 3, 6, 12, and 20 μg/kg nicotine in
random order. Quantitative and quantal behavioral discrimination tasks, used in previous research, were employed. On day 3,
subjects were instructed to self-administer sprays from the 20 μg/kg nicotine versus 0 bottles in a concurrent-choice procedure.
All but one subject (female smoker) learned reliably to discriminate 20 μg/kg nicotine from placebo (≥ 80% correct) on day 1. Nicotine-appropriate responding on day 2 was attenuated in smokers versus never-smokers at 20 μg/kg
on the quantitative task and at 12 μg/kg on the quantal task, suggesting tolerance. There was no difference in responding
at other doses. Smokers also showed attenuated responses on the subjective measure of “head rush”, which was associated with
discrimination responding in both groups. Nicotine self-administration was significantly greater in smokers versus never-smokers,
who self-administered nicotine below chance levels, and was inversely related to discrimination behavior in never-smokers
but unrelated in smokers. Women smokers showed less change in nicotine-appropriate responding across generalization doses,
reported less confidence in discriminating training doses during acquisition on day 1, and tended to self-administer less
nicotine on day 3. These results indicate that smokers may become tolerant to the discriminative stimulus effects of nicotine,
perhaps promoting increased use.
Received: 1 October 1996/Final version: 28 January 1997 相似文献
28.
当代大学生手淫行为比较普遍,很多大学生在上大学之前就养成了难以自控的手淫习惯。大学生手淫既影响了他们的身心健康,对他们在校园里健康成长成材也构成了严重的威胁。从思想与心里教育角度引导大学生正确对待手淫,促使他们养成积极健康的生活习惯,对他们将来人生的健康发展及营造和谐的校园风气具有重要的作用。文章论述了当代大学生手淫的根源、手淫危害、诱发因素、手淫动机及预防、矫治措施。 相似文献
29.
将Wistar大鼠分为三组:肝硬化组,给予四氯化碳等复合因素,给药组,除给CCl4等复合因素外,用赤栀黄合剂灌胃41天;正常组给以一般饮食及饮水。结果,与正常组及给药组相比,硬化组血T3、T4测定值低,甲状腺滤泡中胶质明显减少,滤泡细胞与胶质间空泡增多,滤泡上皮细胞内PAS阳性小滴数日增多。表明在实验性肝硬化期间甲状腺参与了抗疾病的代谢活动,其机理可能是肝硬化时肝细胞合成、转运T3,T4的蛋白质减少。运输中的T3,T4减少,活性甲状腺素不足,从而导致甲状腺代偿性功能活跃。赤栀黄合剂具有保肝,恢复甲状腺素水平的作用。 相似文献
30.
目的:探讨卵巢性腺母细胞瘤的病理特点及鉴别诊断。方法:对2例病理诊断为卵巢性腺母细胞瘤的病例进行临床病理分析。结果:两例均见卵巢性腺母细胞瘤结构。结论:对46XY组型、呈纤维条索状胚条性腺者要特别注意多取材、多切片可以防止漏诊。卵巢性腺母细胞瘤有其特殊的组织形态学特点。纯性腺母细胞瘤为良性,但具有恶性潜能,需与无性细胞瘤、伴环状小管的性索肿瘤及混合性生殖细胞-性索间质性肿瘤相鉴别。 相似文献