全文获取类型
收费全文 | 31903篇 |
免费 | 3148篇 |
国内免费 | 2150篇 |
专业分类
耳鼻咽喉 | 234篇 |
儿科学 | 502篇 |
妇产科学 | 372篇 |
基础医学 | 2599篇 |
口腔科学 | 465篇 |
临床医学 | 4433篇 |
内科学 | 3740篇 |
皮肤病学 | 282篇 |
神经病学 | 1068篇 |
特种医学 | 1039篇 |
外国民族医学 | 7篇 |
外科学 | 2404篇 |
综合类 | 7406篇 |
现状与发展 | 23篇 |
一般理论 | 1篇 |
预防医学 | 2976篇 |
眼科学 | 598篇 |
药学 | 4335篇 |
48篇 | |
中国医学 | 2617篇 |
肿瘤学 | 2052篇 |
出版年
2024年 | 143篇 |
2023年 | 446篇 |
2022年 | 1149篇 |
2021年 | 1410篇 |
2020年 | 1175篇 |
2019年 | 874篇 |
2018年 | 841篇 |
2017年 | 1029篇 |
2016年 | 845篇 |
2015年 | 1435篇 |
2014年 | 1845篇 |
2013年 | 1950篇 |
2012年 | 2922篇 |
2011年 | 2900篇 |
2010年 | 2215篇 |
2009年 | 1881篇 |
2008年 | 2084篇 |
2007年 | 2135篇 |
2006年 | 1945篇 |
2005年 | 1688篇 |
2004年 | 1216篇 |
2003年 | 1193篇 |
2002年 | 932篇 |
2001年 | 677篇 |
2000年 | 596篇 |
1999年 | 412篇 |
1998年 | 234篇 |
1997年 | 225篇 |
1996年 | 152篇 |
1995年 | 150篇 |
1994年 | 122篇 |
1993年 | 72篇 |
1992年 | 50篇 |
1991年 | 41篇 |
1990年 | 45篇 |
1989年 | 35篇 |
1988年 | 31篇 |
1987年 | 27篇 |
1986年 | 34篇 |
1985年 | 17篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
为了研究不同心电序列转换方式及不同谱估计方法对心率变异性(HRV)信号谱分析结果的影响,本文对积分脉冲频率调制(IPFM)模型及修正积分脉冲频率调制(MIPFM)模型在输入不同振幅与频率的正弦信号时所产生的随机点过程,用两种心电序列转换方法进行转换得到仿真HRV信导;然后,采用周期图与自回归(AR)谱估计方法计算这种厉真HRV信号的功率谱。研究结果表明:①对于MIPFM模型产生的随机点过程,同一心电序列转换方法所得出的仿真HRV信号的AR谱与周期图的谱峰功率估计基本一致;而对IPFM模型则不完全一致。②MIPFM模型仿真实验表明,对实际HRV信号谱分析,使用低,高频谱峰功率比(RF)作为反映心脏自主神经张力平衡的指标时,除心电序列传换及谱估计方法可能造成的误差外,当低频谱峰靠近极低频谱峰时,根据RF值解释生理实验结果会有校大误差。③座分析实际HRV信号的工作中,不同心电序列转换方式产生的伪谐波对HRV谱分析结果的影响不大。 相似文献
122.
Objective To investigate the association between the-258T/G polymorphism.in the pro-moter of parkin gene and the risk for sporadic parkinson's disease (SPD) in Guangxi Province, and in relationto the age of onset, of PD patients. Methods PCR-RFLP and sequence analysis were used to determine thegenotype of-258T/G polymorphism between all patients and healthy controls. Results The G allele was morecommon in patients than controls (55.20%:43.33% ,x2=6.898, P<0.05, OR=1.61, 95% CI: 1.13 ~2.30). The frequency of GG genotype was higher in patients than in controls (28.00 %: 18.33%, x2=7.159, P<0.05, OR=2.75, 95% CI : 1.31 ~ 5.77). The frequency of TG + GG genotype was higher in pa-tients than in controls (82.40%:68.33%, x2=6.551, P<0.05, OR=2.17.95%CI: 1.20 ~3.93). Afterbeing stratified by onset age, the frequencies of the G allele and GG genotype were significantly higher in pa-tients with onset age over 50 years than those in controls respectively. On the other hand, the frequency was notsignificantly different between the younger onset PD patients and the controls. Conclusion The parkin promot-er-258T/G polymorphism might be a risk factor for PD in Guangxi Province, and the G allele was increasedwith increasing age. 相似文献
123.
用PCR扩增tim基因检测蓝氏贾第鞭毛虫 总被引:1,自引:1,他引:1
采用聚合酶链反应 (PCR)对蓝氏贾第鞭毛虫 (Giardialamblia)的磷酸丙糖异构酶 (triosephosphateisomerase ,缩写为tim)基因进行特异性扩增 ,结果扩增出 1条 6 83bp的DNA片段。此方法的特异性可高达10 0 % ,而其它DNA样本 ,如日本血吸虫 (Schistosomajaponicum)、刚地弓形虫 (Toxoplasmagondii)、微小隐孢子虫 (Cryptosporidiumparvum)、溶组织内阿米巴 (Entamoebahistolytica)、旋毛虫 (Trichinellaspiralis)和阴道毛滴虫 (Trichomonasvaginalis) ,以及人体血细胞等均未出现扩增反应。本法的敏感性也很高 ,可检测到0 4pg贾第虫包囊的DNA。 13株来自不同地理位置和 或宿主的贾第虫DNA样本在PCR中均各产生 1条长为 6 83bp的目的片段。上述结果表明本实验建立的检测贾第虫的PCR方法有效 相似文献
124.
人际交往训练降低医学生心理应激反应的实验研究 总被引:3,自引:0,他引:3
目的 探讨人际交往训练降低医学生心理应激反应的有效模式 ,以培养交往手段 ,促进身心健康 ,提高学习效率。方法 从云南中医学院中医专业 2 0 0 0级 8个班 ,41 2名学生中随机抽取 2个班 ,共 1 0 6人为被试对象 ,结合专业学习 ,在生理学课堂教学中贯穿人际交往训练 ,训练前后分别测查 90项症状自评量表 ( SCL-90 )和防御方式问卷 ( DSQ) ,并用 Q分类法检验被试课前和课后自我评价。最后 ,对被试和其余 6个班的学生进行生理测验 ,并对测验成绩进行比较。结果 被试在交友信心、乐观豁达、口头表达、积极接纳、说服技巧方面均比训练前有显著和极显著提高 ;且考前心理应激反应明显降低 ,防御方式趋向成熟 ,测验及格率高于其余 6个班。结论 结合专业进行人际交往训练可在近期内改善医学生的心理健康水平 ,有利于提高学习效率 ,深受大学生欢迎 相似文献
125.
Hudson BI Wendt T Bucciarelli LG Rong LL Naka Y Yan SF Schmidt AM 《Antioxidants & redox signaling》2005,7(11-12):1588-1600
The major consequence of long-term diabetes is the increased incidence of disease of the vasculature. Of the underlying mechanisms leading to disease, the accumulation of advanced glycation end products (AGEs), resulting from the associated hyperglycemia, is the most convincing. Interaction of AGEs with their receptor, RAGE, activates numerous signaling pathways leading to activation of proinflammatory and procoagulatory genes. Studies in rodent models of macro- and microvascular disease have demonstrated that blockade of RAGE can prevent development of disease. These observations highlight RAGE as a therapeutic target for treatment of diabetic vascular disease. 相似文献
126.
Reduced expression of tissue inhibitor of metalloproteinase (TIMP)-2 in gestational trophoblastic diseases 总被引:14,自引:0,他引:14
To elucidate the involvement of type IV collagenases [matrix metalloproteinase (MMP)-2 and MMP-9] and their tissue inhibitors (TIMP-1 and TIMP-2) in the development of gestational trophoblastic disease (GTD), we quantified their levels in hydatidiform mole and choriocarcinoma tissues using specific enzyme-linked immunosorbent assays, and the results were compared with those from normal first trimester placenta. Levels of pro-MMP-2 were increased in hydatidiform mole, and they were further elevated in choriocarcinoma. Levels of pro-MMP-9 in choriocarcinoma and those of TIMP-1 in both hydatidiform mole and choriocarcinoma were also increased. In contrast, TIMP-2 levels were markedly decreased in both hydatidiform mole and choriocarcinoma. Similar results were obtained by the tissue culture of first trimester placenta and hydatidiform mole. Gelatin zymography indicated that the levels of both pro- and activated forms of MMP-2 and MMP-9 were higher in hydatidiform mole and choriocarcinoma. The decreased expression of TIMP-2 in hydatidiform mole and choriocarcinoma was confirmed by Western blot, Northern blot and immunohistochemistry, with the decrease being more pronounced in choriocarcinoma. Taken together, the present study shows that both TIMP-2 mRNA and protein levels are markedly decreased in GTD and the imbalance of MMP-TIMP production, shifted toward greater MMP activity, may be involved in the pathogenesis of GTD. 相似文献
127.
Human muscle sympathetic neural and haemodynamic responses to tilt following spaceflight 总被引:6,自引:5,他引:6
Benjamin D. Levine James A. Pawelczyk rew C. Ertl James F. Cox Julie H. Zuckerman ré Diedrich Italo Biaggioni Chester A. Ray Michael L. Smith Satoshi Iwase Mitsuru Saito Yoshiki Sugiyama Tadaaki Mano Rong Zhang Kenichi Iwasaki Lynda D. Lane Jay C. Buckey Jr William H. Cooke Friedhelm J. Baisch David Robertson Dwain L. Eckberg C. Gunnar Blomqvist 《The Journal of physiology》2002,538(1):331-340
128.
Bong Hyo Lee Rong Jie Zhao Jin Young Moon Seong Shoon Yoon Jung-Ae Kim Heeduk An Young Kyu Kwon Meeyul Hwang Seong Hun Choi Insop Shim Bong Hyun Kim Chae Ha Yang 《Neuroscience letters》2008
In our previous study we demonstrated that acupuncture at Shenmen (HT7) points suppressed a decrease of accumbal dopamine (DA) release in ethanol-withdrawn rats. Furthermore, here we found that it inhibited behavioral withdrawal signs of ethanol. In an effort to better understand the mechanisms underlying this inhibition, the potential role of GABA receptor system in acupuncture was investigated. Male Sprague–Dawley rats were treated with 3 g/kg/day of ethanol (20%, w/v) or saline by intraperitoneal injection for 21 days. Following 48 or 72 h of ethanol withdrawal, acupuncture was applied at bilateral HT7 for 1 min. The selective GABAA antagonist bicuculline and the selective GABAB antagonist SCH 50911 were injected intraperitoneally 20 min before acupuncture, respectively. Importantly, suppressive effects of acupuncture on DA deficiency were completely abolished by SCH 50911, but not by bicuculline, whereas ameliorating effects of acupuncture on ethanol withdrawal syndrome were completely blocked either by SCH 50911 or bicuculline. These results suggest that acupuncture at specific acupoint HT7 may normalize the DA release in the mesolimbic system and attenuate withdrawal syndrome through the GABAB receptor system in ethanol-withdrawn rats. 相似文献
129.
MaxiK channel partners: physiological impact 总被引:7,自引:2,他引:7
Rong Lu Abderrahmane Alioua Yogesh Kumar Mansoureh Eghbali Enrico Stefani Ligia Toro 《The Journal of physiology》2006,570(1):65-72
The basic functional unit of the large-conductance, voltage- and Ca2 + -activated K+ (MaxiK, BK, BKCa ) channel is a tetramer of the pore-forming α-subunit (MaxiKα) encoded by a single gene, Slo , holding multiple alternative exons. Depending on the tissue, MaxiKα can associate with modulatory β-subunits (β1–β4) increasing its functional diversity. As MaxiK senses and regulates membrane voltage and intracellular Ca2 + , it links cell excitability with cell signalling and metabolism. Thus, MaxiK is a key regulator of vital body functions, like blood flow, uresis, immunity and neurotransmission. Epilepsy with paroxysmal dyskinesia syndrome has been recognized as a MaxiKα-related disorder caused by a gain-of-function C-terminus mutation. This channel region is also emerging as a key recognition module containing sequences for MaxiKα interaction with its surrounding signalling partners, and its targeting to cell-specific microdomains. The growing list of interacting proteins highlights the possibility that associations with the C-terminus of MaxiKα are dynamic and depending on each cellular environment. We speculate that the molecular multiplicity of the C-terminus (and intracellular loops) dictated by alternative exons may modulate or create additional interacting sites in a tissue-specific manner. A challenge is the dissection of MaxiK macromolecular signalling complexes in different tissues and their temporal association/dissociation according to the stimulus. 相似文献
130.
Vitale E Specchia C Devoto M Angius A Rong S Rocchi M Schwalb M Demelas L Paglietti D Manca S Mastropaolo C Serra G 《American journal of medical genetics》2001,100(1):1-8
Microdeletions in the 22q11 region are associated with a wide range of overlapping phenotypes. The main manifestations of the syndrome include palatal anomalies such as cleft palate or velopharyngeal insufficiency, conotruncal heart defects, hypocalcemia, immune disorders, and minor facial anomalies. Because of the wide variability, facial changes appear to be the most constant manifestation of the syndrome and characteristic for informed physicians. The purpose of this study is to report the preliminary results of a detailed analysis of anthropometric data (35 measurements) in 15 patients (7 females and 8 males between 5 and 38 years of age, all white Europeans) with a 22q11 microdeletion. Objective anthropometric study showed that 19 measurements and 7 indexes were significantly different between 22q11 patients and normative database. The typical face showed a short forehead with an anterior vertical excess. Downslanting eyes and large binocular width were the most common anomalies in the orbital area. The nose showed anomalies with a large root, a short tip, and a narrow alar base. There was a narrowing of the mouth and thin lips. Ears were small and slightly disharmonic for the children. Statistical comparison between children (10 cases) and adults (5 cases) showed that craniofacial assessment was more demonstrative in children than in adults. 相似文献