全文获取类型
收费全文 | 195935篇 |
免费 | 16685篇 |
国内免费 | 7059篇 |
专业分类
耳鼻咽喉 | 1612篇 |
儿科学 | 2521篇 |
妇产科学 | 2195篇 |
基础医学 | 30983篇 |
口腔科学 | 3362篇 |
临床医学 | 14253篇 |
内科学 | 34052篇 |
皮肤病学 | 2707篇 |
神经病学 | 14803篇 |
特种医学 | 4192篇 |
外国民族医学 | 54篇 |
外科学 | 13194篇 |
综合类 | 26450篇 |
现状与发展 | 19篇 |
一般理论 | 6篇 |
预防医学 | 9169篇 |
眼科学 | 1939篇 |
药学 | 32015篇 |
44篇 | |
中国医学 | 8310篇 |
肿瘤学 | 17799篇 |
出版年
2024年 | 367篇 |
2023年 | 3514篇 |
2022年 | 5683篇 |
2021年 | 10019篇 |
2020年 | 7522篇 |
2019年 | 6431篇 |
2018年 | 6207篇 |
2017年 | 6250篇 |
2016年 | 6362篇 |
2015年 | 7471篇 |
2014年 | 11633篇 |
2013年 | 12946篇 |
2012年 | 11539篇 |
2011年 | 13340篇 |
2010年 | 11004篇 |
2009年 | 11258篇 |
2008年 | 10890篇 |
2007年 | 9905篇 |
2006年 | 8851篇 |
2005年 | 7764篇 |
2004年 | 6447篇 |
2003年 | 5757篇 |
2002年 | 4557篇 |
2001年 | 3711篇 |
2000年 | 3138篇 |
1999年 | 2830篇 |
1998年 | 2637篇 |
1997年 | 2450篇 |
1996年 | 2191篇 |
1995年 | 1943篇 |
1994年 | 1761篇 |
1993年 | 1525篇 |
1992年 | 1278篇 |
1991年 | 1208篇 |
1990年 | 991篇 |
1989年 | 832篇 |
1988年 | 792篇 |
1987年 | 665篇 |
1986年 | 600篇 |
1985年 | 945篇 |
1984年 | 900篇 |
1983年 | 630篇 |
1982年 | 639篇 |
1981年 | 511篇 |
1980年 | 431篇 |
1979年 | 353篇 |
1978年 | 230篇 |
1977年 | 193篇 |
1976年 | 183篇 |
1975年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Effects of nilvadipine on the low- and high-voltage activated Ca2+ currents (LVA and HVA ICa, respectively) were compared with other organic Ca2+ antagonists in acutely dissociated rat hippocampal CA1 pyramidal neurons. The inhibitory effects of nilvadipine, amlodipine and flunarizine on LVA ICa were concentration- and use-dependent. The apparent half-maximum inhibitory concentrations (IC50s) at every 1- and 30-s stimulation were 6.3×10−7 M and 1.8×10−6 M for flunarizine, 1.9×10−6 M and 7.6×10−6 M for nilvadipine, and 4.0×10−6 M and 8.0×10−6 M for amlodipine, respectively. Thus, the strength of the use-dependence was in the sequence of nilvadipine>flunarizine>amlodipine. Nilvadipine also inhibited the HVA ICa in a concentration-dependent manner with an IC50 of 1.5×10−7 M. The hippocampal CA1 neurons were observed to have five pharmacologically distinct HVA Ca2+ channel subtypes consisting of L-, N-, P-, Q- and R-types. Nilvadipine selectively inhibited the L-type Ca2+ channel current which comprised 34% of the total HVA ICa. On the other hand, amlodipine non-selectively inhibited the HVA Ca2+ channel subtypes. These results suggest that the inhibitory effect of nilvadipine on the neuronal Ca2+ influx through both LVA and HVA L-type Ca2+ channels, in combination with the cerebral vasodilatory action, may prevent neuronal damage during ischemia. 相似文献
992.
从有参叶中分离得到两种微量皂甙成分,分别为3β,12β,20(S)-三羟基达玛-24(25)-烯-(20-O-α-L-呋喃阿拉伯糖基(1→6)-β-D-吡喃葡萄糖基)-3-O-β-D-吡喃葡萄糖甙(1),和3β,12β,20(S)-三羟基达玛-24(25)-烯-(20-O-α-L-吡喃阿拉伯糖基(1→6)-β-D-吡喃葡萄糖基-3-O-β-D吡喃葡萄糖甙(2),前者为三七参甙-Fe(notoginsenoside-Fe),后者为一新的天然产物,命名为人参皂甙-Rd2(ginsenoside-Rd2)。 相似文献
993.
Yuta Ishizuka Yasushi Ishida Qing-Hua Jin Ayumi Shimokawa Mitsuhiko Saita Kazuo Kato Takato Kunitake Takamitsu Hanamori Yoshio Mitsuyama Hiroshi Kannan 《Brain research》1998,789(1):10
Nitric oxide (NO) has recently been shown to modulate the hypothalamic–pituitary–adrenal axis response to interleukin-1β (IL-1β). We measured levels of nitrite (NO2−) and nitrate (NO3−) in the hypothalamic paraventricular nucleus (PVN) region using an in vivo brain microdialysis technique in conscious rats. Intraperitoneally administered IL-1β produced a significant increase in both NO2− and NO3− levels in the PVN region. We also examined the possible involvement of the abdominal vagal afferent nerves in this effect. In abdominal-vagotomized rats, the increase was significantly attenuated compared to that in sham-operated rats. Our results suggest that the abdominal vagal afferent nerves are involved in intraperitoneally administered IL-1β-induced NO release in the PVN region. 相似文献
994.
目的:了解单核细胞流变特性异常在动脉粥样硬化进程的作用。方法:大耳白兔60只随机分为实验组(AG)40只及对照组(CG)20只,AG给予胆固醇lg.d^-1只^-1在喟养的第2,4,8和12周分别抽血检测单核细胞变形性,膜脂流动性及单核细胞(Ca^2+0i。结果:在兔AS阶段性进程中,单核细胞变形性,膜脂流动性下降趋势,细胞内(Ca^2+)i呈上升趋势,膜流动性与细胞内(Ca^2+)i呈负相关,变 相似文献
995.
In order to establish the safety and efficacy of fluoxetine in subjects over 60 years of age with Type 2 diabetes, a randomized, double-blind, parallel study of 30 obese subjects was undertaken, comparing the use of fluoxetine 60 mg daily with placebo. Subjects were diet controlled with an HbA1 < 14% (reference range 6–9%) and BMI > 29 kg m2. Those taking fluoxetine had a median weight loss of 2.6 kg at 3 months (p < 0.001) and 3.9 kg at 6 months (p < 0–02), compared with weight loss in the placebo group of 0.1 kg and 0.0 kg at 3 and 6 months, respectively. Improved glycaemic control was also demonstrated in the fluoxetine group compared with placebo, initial HbA1 levels of 8.0% vs 8.7% (NS) falling at 4 months by 0.9% (p < 0.02) and at six months by 0.9% (p < 0.02). No sustained improvement in fasting blood glucose levels was demonstrated. Reporting of adverse events was similar in both groups. Fluoxetine in the short term aids weight loss and improves glycaemic control without a significant increase in adverse events in elderly Type 2 diabetic subjects. 相似文献
996.
Seven cases of granular cell Abrikossoff tumours of the larynx and tongue are reported: four in the tongue and three in the larynx. All of these tumours were removed with the carbon dioxide (CO2) laser. The anatomical site of the origin and clinical features of granular cell tumours (GCT) are not specific. Histological, light microscopic, electron microscopic (EM) and immunohistochemical studies are required for diagnosis. The histogenesis and cellular derivation of GCTs is still controversial. The biological potential and lack of cellular atypia define a benign process. However, it is important to take into account that these tumours have ill-defined borders without a capsule. Radiation therapy has proved ineffective in the past. Surgical excision with a wide margin is required. Because of numerous advantages, for example, no bleeding, no oedema, minimal pain and quick recovery, CO2 laser removal is the treatment of choice. The authors have not seen any recurrence or complications. 相似文献
997.
为探索喉气管狭窄松解瘢痕组织的方法,近四年来,对七例严重的喉气管狭窄病人进行开放性“T”型硅胶管置入术,术中应用CO2激光切除、松解瘢痕组织,所有病人术后8~12月成功拔管。证明CO2激光为喉气管狭窄重建术的一种有效辅助治疗手段 相似文献
998.
选择46例晚期肺癌患者应用LAK/IL-2疗法观察患者近期临床改善情况及治疗前后其免疫指标的变化情况。选择胎儿胸腺淋巴组织作前体细胞,体外用重组IL-2诱导制备LAK细胞,每输3次LAK细胞为1疗程,每次输入细胞数为05×109,化疗以采用丝裂霉素、长春新碱、顺铂或卡铂、鬼臼乙叉甙为主的方案,治疗结果:本组患者治疗有效率(CR+PR)达70%,同时患者免疫指标好转。本研究提示LAK/IL-2联合疗法临床近期疗效较满意,同时可显著改善机体免疫功能,是晚期肺癌患者一种可行的有效方法 相似文献
999.
Stefan Somlo 《Clinical and experimental nephrology》1998,2(3):211-217
Conclusion The past decade has seen extraordinary progress in the study of autosomal-dominant polycystic kidney disease. The 2 major
genes for this disorder have been identified. Animal models of ADPKD have been produced. The molecular basis of the disease
has been characterized. ADPKD is a “second-hit” disease, much like many cancer predisposition syndromes. This has profound
implications for our understanding. The progression of ADPKD in individual patients is likely related more to their individual
rate of acquisition of second hits at thePKD1 orPKD2 locus than to the inherited germ line mutation itself. Therapeutic approaches will perhaps now be considered, which will
include interventions that may limit the rate at which somatic mutations occur in the kidney. The major focus of research
at present is to elucidate the normal functions ofPKD1 andPKD2. Protein binding partners are being sought for both proteins. The possible calcium channel function ofPKD2 is being investigated. The downstream effects of cellular deficiency of either protein are likely to yield many clues. Modifying
genetic factors that may independently affect disease progression are likely to be identified using the several mouse models.
Perhaps the next decade will bring great strides in understanding and in potential therapy for this common disease.
This paper was presented at the 2nd International Forum “The Frontiers of Nephrology,” Tokyo, May 10, 1998. 相似文献
1000.
In order to find out anti-platelet activating factor (PAF) from natural resources, Korean medicinal plants used for the treatments
of peripheral circulation disorders were tested for their possible protective effects on PAF-induced anaphylactic shock. From
the above screening, the methanol extract ofGentiana scabra showed a potent antagonistic activity against PAF. Water suspension of the extract was partitioned with CH2Cl2 and EtOAc, successively. The EtOAc fraction which showed the highest activity was chromatographed on silica gel to yield
6 fractions. From the fraction which showed higher PAF-antagonistic activity than the other fractions, compound1 was isolated by recrystallization. On the basis of spectral data, compound1 was identified as 2-hydroxy-3-methoxybenzoic acid glucose ester. The compound prevented the mice from the PAF-induced death
at a dose of 300 μg/mouse. 相似文献