全文获取类型
收费全文 | 539546篇 |
免费 | 49037篇 |
国内免费 | 36756篇 |
专业分类
耳鼻咽喉 | 4348篇 |
儿科学 | 6534篇 |
妇产科学 | 6650篇 |
基础医学 | 60415篇 |
口腔科学 | 8925篇 |
临床医学 | 75689篇 |
内科学 | 74548篇 |
皮肤病学 | 5740篇 |
神经病学 | 27300篇 |
特种医学 | 19937篇 |
外国民族医学 | 313篇 |
外科学 | 49422篇 |
综合类 | 97175篇 |
现状与发展 | 124篇 |
一般理论 | 48篇 |
预防医学 | 37574篇 |
眼科学 | 15685篇 |
药学 | 57862篇 |
575篇 | |
中国医学 | 33804篇 |
肿瘤学 | 42671篇 |
出版年
2024年 | 1717篇 |
2023年 | 7696篇 |
2022年 | 20252篇 |
2021年 | 25781篇 |
2020年 | 20000篇 |
2019年 | 16669篇 |
2018年 | 17497篇 |
2017年 | 16562篇 |
2016年 | 15351篇 |
2015年 | 23687篇 |
2014年 | 29589篇 |
2013年 | 26761篇 |
2012年 | 39680篇 |
2011年 | 44830篇 |
2010年 | 29270篇 |
2009年 | 23719篇 |
2008年 | 29846篇 |
2007年 | 29714篇 |
2006年 | 29096篇 |
2005年 | 28230篇 |
2004年 | 18371篇 |
2003年 | 17589篇 |
2002年 | 14556篇 |
2001年 | 12799篇 |
2000年 | 12897篇 |
1999年 | 13210篇 |
1998年 | 8258篇 |
1997年 | 8016篇 |
1996年 | 6316篇 |
1995年 | 5914篇 |
1994年 | 4945篇 |
1993年 | 3205篇 |
1992年 | 4078篇 |
1991年 | 3528篇 |
1990年 | 2921篇 |
1989年 | 2523篇 |
1988年 | 2193篇 |
1987年 | 1948篇 |
1986年 | 1574篇 |
1985年 | 1155篇 |
1984年 | 678篇 |
1983年 | 494篇 |
1982年 | 279篇 |
1981年 | 290篇 |
1980年 | 218篇 |
1979年 | 284篇 |
1978年 | 121篇 |
1977年 | 106篇 |
1975年 | 86篇 |
1974年 | 98篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Effect of endothelium on the actions of sympathetic and sensory nerves in the perfused rat mesentery. 总被引:4,自引:0,他引:4
We and others have previously demonstrated that pretreatment with capsaicin produces an augmentation of vasoconstrictor responses to transmural nerve stimulation. In the present study, removal of endothelium by saponin or inhibition of nitric oxide synthesis by N omega-nitro-L-arginine methyl ester produced an augmentation of vasoconstrictor responses to transmural nerve stimulation, responses which were further potentiated after treatment with capsaicin to desensitize sensory nerves. Capsaicin treatment decreased vasodilator responses to acetylcholine, but only at low acetylcholine concentrations. Potentiation by capsaicin of vasoconstrictor responses to transmural nerve stimulation was not affected by indomethacin. In the presence of guanethidine and methoxamine, transmural nerve stimulation caused vasodilator responses in the perfused rat mesentery. These responses were unaffected by removal of endothelium, as were vasodilator responses to exogenous calcitonin gene-related peptide (CGRP). In contrast, substance P did not produce any relaxation in the methoxamine-contracted mesentery. This study suggests that facilitation of vasoconstrictor responses to transmural nerve stimulation after capsaicin treatment primarily reflects inhibition of sensory nerve effects resulting in an increase of sympathetic vasoconstrictor actions. The present results also suggest that vasodilator responses to sensory nerve activation or exogenous CGRP are endothelium-independent and that substance P does not significantly contribute to modulation of vascular tone in the rat mesentery. 相似文献
992.
Xu Jingying Liu Xinling Ma Zhuhong Chen LingDepartment of Acupuncture & Moxibustion General Hospital of PLA Beijing China 《世界针灸杂志》1994,(1)
In this paper,250 cases of headache,shoulder pain,lumbago and leg pain weretreated with 20%Angelicae Sinensis mixed with Vitamine B_(12) point-injection therapy.The total effective rate was 95.2%and in which the cure rate was 53.6%.Authors have found a close correlation between the effectiveness and the duration of disease. 相似文献
993.
测定75例白癜风患者周围血象、血小板相关抗体(PAIgG)、血小板粘附及聚集、第3因子功能、高岭土部分凝血活酶时间(KPTT)、一期凝血酶原时间(PT)。结果发现白癜风患者血小板减少,PAIgG增高、聚集时间延长。提示这种异常与免疫有关。 相似文献
994.
用紫外分光光度法测定银杏叶提取物中芦丁的含量,结果表明:以60%丙酮或70%乙醇提取银杏叶,所得提取物的芦丁含量为33.27%~43.38%。 相似文献
995.
促甲状腺素释放激素拮抗β-内啡肽对心血管的抑制作用 总被引:2,自引:0,他引:2
本研究用兔侧脑室给药观察了促甲状腺素释放激素(TRH)对β-内啡肽心血管抑制作用的影响。结果表示,β-内啡肽(10μg,icv)能显著抑制兔心血管功能,表现为血压下降,心机收缩力指标如左室收缩压(LVSP),心室内压最大上升和下降速率(±dp/dtmax),心肌纤维收缩速度(Vce40,Vpm)和心肌收缩向量环面积(Lp)明显降低。β-内啡肽的这一作用可被TRH(50μg,icv)取消,阿片受体拮抗剂纳洛酮(NAL,50μg,icv)也可拮抗β-内啡肽的心血管抑制作用,表明,TRH与内源性阿片肽系统有密切关系,结合以前的实验结果提示TRH拮抗β-内啡肽的心血管抑制作用有可能是作用在阿片受体上的。 相似文献
996.
The neuroendocrine light green cells (LGCs) control body growth and metabolism of the freshwater snail, Lymnaea stagnalis. These cells, located in the cerebral ganglia, use the peripheries of the median lip nerves (MLNs) as the neurohemal area. The LGCs express four members of a gene family encoding the precursors of distinct though related molluscan insulin-related peptides (MIPs). The molecular characterization and biosynthesis of MIPs have been investigated. MLN extracts were first size fractionated using gel permeation chromatography, and a major peak that coeluted with bovine insulin was further resolved using reverse phase high performance liquid chromatography. Amino acid composition analysis revealed that the four MIPs were present, as encoded by the MIP genes. Biosynthesis and axonal transport of the MIPs were studied in vitro with LGC systems in a series of pulse-chase incubations in combination with gel permeation chromatography analysis. During the pulse period of 20 min MIP precursors were formed in the LGC cell bodies. During the subsequent chase period these precursors were converted to MIPs and C peptides, which were transported to the LGC axon terminals in the MLNs for storage and release. The MIP precursors seem to be processed similarly to the insulin precursor in pancreatic islets. 相似文献
997.
上皮样肉瘤的病理学研究 总被引:4,自引:0,他引:4
Thirteen cases of epithelioid sarcoma were studied by light microscopy (LM), electron microscopy and immunohistochemical technique. LM revealed a nodular pattern of the tumor cells, which consisted of various degrees of a typical epithelioid cells and plump spindle-shaped cells. Irregular necrosis was seen in the centre of some nodules. Ultrastructurally the tumor cells exhibited abundant intermediate filaments, desmosome-like cell junctions and small intercellular spaces surrounded by microvilli. Immunohistochemically, there was positivity for vimentin and keratin. The author discussed diagnosis, differential diagnosis and histogenesis of epithelioid sarcoma. 相似文献
998.
环丙沙星治疗急性细菌性痢疾29例临床疗效观察 总被引:5,自引:1,他引:4
食源性急性菌例29例中28例大便培养为弗氏2a志贺氏菌。经2天吡哌酸加TMP短程快速治疗,29例无一例治愈。依据药敏试验改用环丙沙星治疗,其中11例感染严重者先予静脉点滴,每12小时200mg,1 ̄2天,症状好转即改口服,每12小时250mg。另18例口服,疗程均为4天。用药后,平均退热时间1.32天,大便次数恢复正常时间平均2.10天,大便常规正常时间平均2.86天,28例大便培养阳性者,平均阴 相似文献
999.
1000.
The effects of combined use of earthworm extract(912)and HpD-laser on the produc-tion of reactive oxygen and the biosynthesis of DNA in S_(180) tumor cells were studied throughchemiluminescence measurement and[~3H]-TdR incorporation assay.The results showed that as com-pared with the control,the intensity of chemiluminescence emitted by tumor cells treatedsimultaneously with 912 and HpD-laser was enhanced more than ten-folds,while that treated with912 or HpD-laser alone was increased only 2~4 folds.The[~3H]-TdR incorporation into tumorcells of the former group was inhibited upto 74.1%,and that of the latter groups decreased onlyby 42.2% and 40.0%,respectively.In accordance with these biochemical changes,the ultrastructuraldamage of tumor cells of the former,combinedly treated group appeared to be the most serious.This suggests an additive effect of 912 with HpD-laser on tumor cells.In addition,if free radicalscavengers,such as catalase and superoxide dismutase,were added to the reaction systembefore chemiluminescence assay,the luminescent enhancement effect mentioned above was dramaticallyalleviated,implying the presence of O_2~ and H_2O_2 in the system.Therefore,as to the toxic effecton tumor cells,912 and HpD-laser are not only additive in efficiency,but also similar in theunderlying mechanism of action. 相似文献