全文获取类型
收费全文 | 276744篇 |
免费 | 22835篇 |
国内免费 | 7170篇 |
专业分类
耳鼻咽喉 | 3552篇 |
儿科学 | 5058篇 |
妇产科学 | 4545篇 |
基础医学 | 28187篇 |
口腔科学 | 8094篇 |
临床医学 | 22994篇 |
内科学 | 30586篇 |
皮肤病学 | 3382篇 |
神经病学 | 20214篇 |
特种医学 | 6530篇 |
外国民族医学 | 31篇 |
外科学 | 24317篇 |
综合类 | 41132篇 |
现状与发展 | 17篇 |
一般理论 | 24篇 |
预防医学 | 30097篇 |
眼科学 | 2602篇 |
药学 | 32474篇 |
349篇 | |
中国医学 | 27400篇 |
肿瘤学 | 15164篇 |
出版年
2024年 | 1072篇 |
2023年 | 4955篇 |
2022年 | 9308篇 |
2021年 | 12292篇 |
2020年 | 11823篇 |
2019年 | 13225篇 |
2018年 | 11829篇 |
2017年 | 10449篇 |
2016年 | 9623篇 |
2015年 | 9428篇 |
2014年 | 17681篇 |
2013年 | 19220篇 |
2012年 | 16258篇 |
2011年 | 17741篇 |
2010年 | 14439篇 |
2009年 | 13054篇 |
2008年 | 12660篇 |
2007年 | 12390篇 |
2006年 | 10614篇 |
2005年 | 9017篇 |
2004年 | 7779篇 |
2003年 | 6993篇 |
2002年 | 5501篇 |
2001年 | 4626篇 |
2000年 | 4162篇 |
1999年 | 3469篇 |
1998年 | 3190篇 |
1997年 | 2907篇 |
1996年 | 2489篇 |
1995年 | 2171篇 |
1994年 | 1973篇 |
1993年 | 1773篇 |
1992年 | 1476篇 |
1991年 | 1364篇 |
1990年 | 1116篇 |
1989年 | 1028篇 |
1988年 | 930篇 |
1987年 | 833篇 |
1986年 | 810篇 |
1985年 | 2117篇 |
1984年 | 2329篇 |
1983年 | 1460篇 |
1982年 | 1933篇 |
1981年 | 1363篇 |
1980年 | 1139篇 |
1979年 | 980篇 |
1978年 | 794篇 |
1977年 | 599篇 |
1976年 | 722篇 |
1975年 | 506篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的:观察盐酸托烷思琼对预防脑动脉瘤栓塞术患者术后恶心呕吐(PONV)的有效性和安全性。方法:选择行颅内动脉瘤栓塞术患者45例,随机分为3组,每组15例,于手术结束前30分钟A组患者缓慢静注盐酸托烷思琼5mg,B组患者缓慢静注盐酸托烷思琼3mg,C组患者给予生理盐水。术后观察并记录以下指标:(1)术后24h内恶心呕吐发生率及强度;(2)术后2、8h镇静评分(OAA/S);(3)术后2、8h平均动脉压(MAP),心率(HR);(4)各组不良反应的发生情况。结果:术后24h内两治疗组恶心呕吐发生率显著低于对照组,差异有统计学意义(P<0.05或P<0.01)。托烷思琼5mg组恶心呕吐发生率略低于3mg组,但差异无统计学意义(P>0.05)。结论:托烷思琼可降低脑动脉瘤栓塞术患者术后恶心呕吐的发生率。托烷思琼3mg不仅可以减少药物用量,而且能减少副作用的发生,是一种经济、有效、安全的止吐方法。 相似文献
92.
Fujihiko Iwata M.D. Yoshio Hanawa M.D. Hirotada Takashima M.D. Keichou Shimoura M.D. Youhei Nishibayashi M.D. 《Pediatrics international》1992,34(1):84-86
The pathogenesis and etiology of Kawasaki disease are unknown, but some studies suggest increased genetic susceptibility. The case is presented of an infant with Kawasaki disease whose father suffered from the same illness 21 years previously. The A, B and C loci of the HLA antigens were examined. 相似文献
93.
94.
95.
表皮生长因子及其受体与流产关系的探讨 总被引:4,自引:0,他引:4
采用放射免疫竞争抑制饱和分析法,检测47例难免流产患者,65例人工流产及20例健康非孕妇女血清表皮生长因子(EGF)水平;同时采用免疫组织化学法检测流产者胚胎组织中表皮生长因子受体(EGFR)表达程度。结果:人工流产组血清EGF水平高于自然流产及非孕妇女,而自然流产与非孕妇女差异无显著性;胚胎组织中EGFR阳性表达率人工流产组明显高于自然流产组。提示:EGF通过与其受体结合对妊娠维持、胚胎及胎儿的 相似文献
96.
Xinyu D. Li Esperanza Arias Ramamohana R. Jonnala Shyamala Mruthinti Jerry J. Buccafusco 《Journal of molecular neuroscience : MN》1996,27(3):325-336
The ability of nicotine to induce a cytoprotective or neuroprotective action occurs through several down-stream mechanisms.
One possibility is that the drug increases the expression of tyrosine kinase A (TrkA) nerve growth factor (NGF) receptors.
Certain β-amyloid peptides (e.g., Aβ1–42) have been shown to bind with high affinity to α7 nicotinic receptors and thus interfere
with a potentially neurotrophic influence. Treatment of differentiated PC-12 cells with nicotine produced a concentration-dependent
increase in cell-surface TrkA receptors that occurred concomitantly with cytoprotection. The effect of nicotine was blocked
by either of the α7 receptor antagonists α-bungarotoxin (α-BTX) or methyllycaconatine. The cytoprotective action of nicotine
also was inhibited by pretreatment with 10–100 nM Aβ1–42. Nicotine also was administered (four injections of 30 μg, spaced evenly over 24 h) to rats by direct injection into
a lateral cerebral ventricle. Brain TrkA expression was increased significantly in hippocampus and entorhinal cortex (up to
32% above control), with no changes found in cerebral cortex or hypothalamus. The nicotine-induced increases in TrKA expression
in hippocampus and entorhinal cortex were significantly inhibited by 10 μg α-BTX or by 10 nmol Aβ1–42. Therefore, physiologically
relevant concentrations of Aβ1–42 can prevent nicotine-induced TrkA receptor expression in brain regions containing cholinergic
neurons susceptible to the neurotoxicity associated with Alzheimer’s disease. 相似文献
97.
LYNDA E ALBERTYN 《Journal of Medical Imaging and Radiation Oncology》1992,36(1):17-22
Both systemic and local therapy, for conditions of the breast and unrelated to it, may produce manuno-graphic changes. Some of these are characteristic, such as the pattern of scarring seen in reduction mammo-plasty. In many other instances, however, the changes produced overlap features commonly seen in malignancy. A knowledge of the timing, natural history and spectrum of these changes will aid mammographic interpretation. 相似文献
98.
Andreas Jovanovic Engelbert A.J.M. Schulten Isaäc van der Waal 《Community dentistry and oral epidemiology》1992,20(2):94-96
The referral pattern of 140 Dutch patients with oral mucosal lesions, who had been referred to a Department of Oral & Maxillofacial Surgery and Oral Pathology, shows that patients with oral mucosal lesions consult the dentist as often as the family doctor as the first source of help or information. Furthermore, family doctors were much more used to refer patients with oral mucosal disease to medical specialists rather than to the dentist or the oral and maxillofacial surgeon. 相似文献
99.
小包装全氟丙烷气体动力学实验研究 总被引:1,自引:0,他引:1
为检验塑料小包装全氟丙烷气体(C3F8)在不同包装和储存方法时浓度变化,将装有5~7mlC3F8的聚氯乙烯小袋,根据不同储藏温度和外包装方法随机分成四组:(1)22℃聚乙烯外包装,(2)36℃聚乙烯外包装,(3)22℃铝箔真空外包装,(4)-29℃聚乙烯外包装;每一组C3F8小袋气体存放一定时间后,应用气相色谱分析方法进行浓度测量。结果:第3组C3F8浓度最高和稳定,第2组浓度随放置时间降低最明显,第4组是临床应用气体的储藏和包装方法,其30天样本浓度和第3组相等,但放置一年时浓度降低。结果显示:塑料小包装C3F8予以铝箔真空外包装是一种可行的方法,利于C3F8运输和普及;聚乙烯外包装的C3F8,应放在-29℃保存,时间不超过一年。 相似文献
100.
Da-Nian Zhu, Long-Mei Xue, Peng Li. Effect of central muscarine receptor blockade. with DKJ-21 on the blood pressure and heart rote in stress-induced hypertensive rats.
The experiments were performed on Wistar or Sprague-Dawley rats of both sexes divided at random into stress and control groups. The rats in the stress groups were put into cages and subjected to electric foot-shocks and noises for 9-15 days, which caused an increase in blood pressure (BP) and heart rate (HR). In hypertensive rats DKJ-21 (4mg/lml) was injected intravenously (i.v.), and 0.5-1.0h after administration the BP and HR dropped from the high level to normotensive level. In normotensive rats, however, administration of DKJ-21 had no effect on BP or HR. In separate groups of normotensive rats, pretreatment of DKJ-21 (4 mg/l ml, i.v.) blocked the pressor and tachycardiac effect induced by microinjection of physostigmine (0.4μg/0.1 /μl/site), corticosterone (40μg/0.1μl/site) or aldosterone (40 μg/0.1 μl/site) into the rostral ventrolateral medulla (rVLM). Furthermore, DKJ-21 also attenuated the enhancement of the pressor response to stimulation of the defense area in the midbrain, which was induced by microinjection of drugs (mentioned above) into the rVLM. These results indicate that i.v. DKJ-21 can selectively block the muscarinic receptors in the rVLM in stress-induced hypertensive rats, which suggests that abnormal enhancement of cholinergic mechanism in the rVLM may be related to hypertensive effects of corticoids in this area. 相似文献
The experiments were performed on Wistar or Sprague-Dawley rats of both sexes divided at random into stress and control groups. The rats in the stress groups were put into cages and subjected to electric foot-shocks and noises for 9-15 days, which caused an increase in blood pressure (BP) and heart rate (HR). In hypertensive rats DKJ-21 (4mg/lml) was injected intravenously (i.v.), and 0.5-1.0h after administration the BP and HR dropped from the high level to normotensive level. In normotensive rats, however, administration of DKJ-21 had no effect on BP or HR. In separate groups of normotensive rats, pretreatment of DKJ-21 (4 mg/l ml, i.v.) blocked the pressor and tachycardiac effect induced by microinjection of physostigmine (0.4μg/0.1 /μl/site), corticosterone (40μg/0.1μl/site) or aldosterone (40 μg/0.1 μl/site) into the rostral ventrolateral medulla (rVLM). Furthermore, DKJ-21 also attenuated the enhancement of the pressor response to stimulation of the defense area in the midbrain, which was induced by microinjection of drugs (mentioned above) into the rVLM. These results indicate that i.v. DKJ-21 can selectively block the muscarinic receptors in the rVLM in stress-induced hypertensive rats, which suggests that abnormal enhancement of cholinergic mechanism in the rVLM may be related to hypertensive effects of corticoids in this area. 相似文献