首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   77847篇
  免费   6796篇
  国内免费   3195篇
耳鼻咽喉   673篇
儿科学   1476篇
妇产科学   1374篇
基础医学   8859篇
口腔科学   1464篇
临床医学   9256篇
内科学   14403篇
皮肤病学   1264篇
神经病学   4725篇
特种医学   2184篇
外国民族医学   26篇
外科学   8245篇
综合类   9614篇
现状与发展   7篇
一般理论   14篇
预防医学   6164篇
眼科学   2072篇
药学   7397篇
  78篇
中国医学   3673篇
肿瘤学   4870篇
  2024年   259篇
  2023年   1097篇
  2022年   2725篇
  2021年   3949篇
  2020年   2854篇
  2019年   2658篇
  2018年   2842篇
  2017年   2457篇
  2016年   2198篇
  2015年   3161篇
  2014年   4234篇
  2013年   4469篇
  2012年   6618篇
  2011年   6746篇
  2010年   4452篇
  2009年   3839篇
  2008年   4713篇
  2007年   4597篇
  2006年   4214篇
  2005年   3832篇
  2004年   2841篇
  2003年   2761篇
  2002年   2264篇
  2001年   913篇
  2000年   937篇
  1999年   878篇
  1998年   645篇
  1997年   624篇
  1996年   490篇
  1995年   429篇
  1994年   354篇
  1993年   242篇
  1992年   303篇
  1991年   216篇
  1990年   209篇
  1989年   171篇
  1988年   171篇
  1987年   150篇
  1986年   150篇
  1985年   126篇
  1984年   78篇
  1983年   71篇
  1982年   80篇
  1981年   85篇
  1980年   47篇
  1979年   75篇
  1977年   46篇
  1976年   46篇
  1974年   49篇
  1973年   44篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
在微量注射大量肝脏mRNA之后,通过电压箝方法进行功能鉴定,两栖类卵母细胞成功地表达了AVPV1a受体。但在灌流AV4-8溶液时,却不能诱导卵母细胞产生内向振荡电流反应。提示AVP4-8不能通过AVPV1a受体而介导生理学效应。  相似文献   
22.
Quantitative receptor autoradiography was used to study possible alterations of the densities of multiple serotonin (5-HT) receptor subtypes and of serotonin transporter in the brain of 5-HT(2C) receptor knockout mice. The radioligands employed were [(3)H]citalopram, [(3)H]WAY100,635, [(3)H]8-OH-DPAT, [(3)H]GR125743, [(3)H]sumatriptan, [(3)H]MDL100,907, [(125)I](+/-)DOI, [(3)H]mesulergine, [(3)H]5-HT, [(3)H]GR113808, and [(3)H]5-CT. As expected, radioligands that label 5-HT(2C) receptors showed a complete absence of labeling in mutant mice choroid plexus and significantly reduced densities in other brain regions expressing 5-HT(2C) receptors. With the rest of the radioligands, no significant alterations in the densities of labeled sites were found in any brain region. In situ hybridization showed no changes in 5-HT(2A) receptor and serotonin transporter mRNA levels, whereas 5-HT(2C) receptor mRNA levels were reduced in certain brain regions. The present results indicate that the mouse serotonergic system does not exhibit compensatory up- or down-regulation of the majority of its components (serotonin transporter and most 5-HT receptor subtypes) in response to the absence of 5-HT(2C) receptors.  相似文献   
23.
24.
Forty depressed patients and 36 age- and sex-matched controls were given 250 μg ACTH1–24 by bolus. Plasma steroid hormone levels were measured prior to and 60 min after ACTH administration. The depressed patients had significantly greater cortisol (F), 11-deoxycortisol (S), androstenedione (AD), and 17-hydroxyprogesterone (17-OHP) responses (delta; p<0.05) and a marginally greater 11β-hydroxyandrostenedione (11β-OHAD) response (delta; p=0.091) than the controls. There was no significant difference in the corticosterone (B) response between the two groups.

With the exception of 11β-OHAD, all the steroid hormones were significantly negatively correlated with age in the controls, but only S and AD marginally demonstrated this relationship in the depressed patients. F, S, AD, 17-OHP, and B, but not 11β-OHAD, were significantly positively correlated with each other in the controls, but only F was significantly correlated with AD in the depressed patients. These data suggest that the hypercortisolemia found in some depressed patients involves increased precursor and metabolite levels both at baseline and in response to exogenous ACTH, compared to controls. Furthermore, variability in these precursors is greater in depressed patients, and their relationship to age is lost. These findings are consistent with the hypothesis that adrenal products other than cortisol also could be related to affective symptoms.  相似文献   

25.
26.
Because of the development of hypercoagulability and the deposition of fibrin in the penis during erection a study of the possible role of platelets in this process was undertaken. Platelet response was studied in 9 adult chacma baboons (Papio ursinus) using autologous in vitro indium-111-labelled platelets and sequential scintigraphy of the penis during erection. The blood pooling pattern was obtained using in vivo technetium-99m-labelled red cells in a similar investigation. A statistically significant retention of platelets occurred during and after erection, which could not be attributed to blood pooling (P less than 0,05). Entrapment of platelets could lead to enhanced activity and activation, and might play a significant role in hypercoagulability and fibrin deposition during erection. Therefore platelets could be an important factor in the pathogenesis of ageing impotence.  相似文献   
27.
We report on a boy with severe radial hypoplasia, absent thumbs and patellae, short stature, persistent diarrhea, slender nose and normal intelligence as another example of the RAPADILINO syndrome. © 1992 Wiley-Liss, Inc.  相似文献   
28.
A chiral poly(3-substituted isobutyl D -aspartate) 12 was synthesized by polymerization of the chiral β-lactam 11 derived from D -glyceraldehyde. The new polyamide was characterized by elemental analyses, and infrared, 1H- and 13C nuclear magnetic resonance spectroscopies. The molecular weight was estimated as 543 000 and 230 000 on the basis of viscosimetric measurements and gel-permeation chromatography, respectively. Polyamide 12 is soluble in a variety of organic solvents including chloroform.  相似文献   
29.
目的:获得SENV-D亚型ORF1-C端蛋白基因序列,并进行表达,为进一步研究及诊断、治疗应用奠定基础.方法:用PCR法从SENV阳性血清中获得SENV-DORF1C端基因,测序验证后,构建了pQE30-SENV-D重组表达质粒,并经过转化E.coli M15,IPTG诱导表达,Western blot分析表达结果.结果:获得了正确序列的SENV-D亚型ORF1-C端蛋白基因序列,表达出Mr约为38×103的蛋白.表达蛋白能与患者血清中相应的抗体结合,发生抗原抗体反应.结论:成功获得并表达了SENV-D-ORF1-C端蛋白,并经Western blot印迹法证实能与阳性血清中的抗体发生抗原抗体反应,有可能用于检测SENV-D抗体.为今后进一步研究有助于疫情监测及早期发现感染者的抗体奠定了坚实的基础.  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号