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   5010篇
  免费   3篇
  国内免费   1篇
耳鼻咽喉   3篇
儿科学   3394篇
妇产科学   22篇
基础医学   163篇
口腔科学   16篇
临床医学   127篇
内科学   214篇
皮肤病学   8篇
神经病学   196篇
特种医学   25篇
外科学   234篇
综合类   16篇
预防医学   333篇
眼科学   38篇
药学   208篇
中国医学   1篇
肿瘤学   16篇
  2023年   2篇
  2021年   2篇
  2020年   5篇
  2019年   111篇
  2018年   120篇
  2017年   113篇
  2016年   1篇
  2015年   2篇
  2014年   4篇
  2013年   2篇
  2012年   5篇
  2011年   1篇
  2010年   4篇
  2009年   8篇
  2008年   5篇
  2007年   1篇
  2006年   4篇
  2005年   15篇
  2004年   14篇
  2003年   18篇
  2002年   2篇
  2001年   1篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   2篇
  1995年   4篇
  1994年   9篇
  1992年   1篇
  1991年   1篇
  1985年   85篇
  1984年   122篇
  1983年   109篇
  1982年   505篇
  1981年   479篇
  1980年   458篇
  1979年   521篇
  1978年   508篇
  1977年   411篇
  1976年   396篇
  1975年   304篇
  1974年   350篇
  1973年   305篇
排序方式: 共有5014条查询结果,搜索用时 31 毫秒
1.
高分子染料是一类本身固有颜色的高分子化合物,它兼有染料和高聚物的双重性质。因此既可作为色料也可作为高聚物而应用于许多领域。本文较详细阐述了聚合染料的种类,合成方法及应用情况。  相似文献   
2.
3.
目的:评估中澳农村卫生综合项目乡镇卫生院院长管理知识培训效果。方法:采用问卷调查、焦点组访谈、个人深入访谈、现场走访等方法进行现况调查。结果:多数卫生院院长在管理基础知识的收获、分析问题的能力、观念的转变、管理行为的改变、员工士气的提高、卫生服务的改善方面都有所提高;被调查的三所中心乡卫生院的所有职工都认为所在卫生院近半年来的工作总体上有所改进;病人及周围居民对三所卫生院的总体满意度都在55%以上。结论:乡镇卫生院管理培训效果良好。  相似文献   
4.
After injecting a horseradish peroxidase (HRP) solution into the vestibular apparatus in goldfish (Carassius auratus), cells in the medulla oblongata exhibited retrogradely transported HRP reaction product. These labeled cells were confined to 3 nuclei, i.e. the nucleus motorius tegmenti of Bartelmez (with the most prominent labeled cell groups), the ventral vestibular nucleus (Dieter's nucleus) and the medial vestibular nucleus. We consider these labeled cells to be the origin of the efferent innervation to the vestibular apparatus in goldfish. Neurons providing efferent innervation to the sensory periphery in the nucleus motorius tegmenti have, as yet, not been described.  相似文献   
5.
The turnover rates of adrenaline in the medial preoptic area and mediobasal hypothalamus, areas which, respectively, include the cell bodies and terminals of luteinizing hormone-releasing hormone neurons, have been measured in female rats on pro-oestrus, the day of the preovulatory surge of luteinizing hormone, and on dioestrus, the preceding day. A rise in the rate of turnover was found in the medial preoptic area coinciding with the surge of luteinizing hormone in the late afternoon of pro-oestrus; the rate of turnover at this time was higher than at the same time on dioestrus. No changes in turnover rate were found in the mediobasal hypothalamus within either of these days.The results indicate that the adrenaline-containing projections to the preoptic area may be actively involved in the production of the spontaneous preovulatory surge of luteinizing hormone in rats.  相似文献   
6.
The neurotoxic hexacarbon 2,5-hexanedione (2,5-HD) produces testicular atrophy in experimental animals. To examine the morphogenesis of the testicular lesion, 1.0% 2,5-HD was provided in the drinking water of adult F-344 rats for up to 6 weeks. After 3 weeks of administration, there were occasional large vacuoles in the basal region of the germinal epithelium. At 4 weeks, these vacuoles were much larger and more numerous; electron microscopy demonstrated that they were derived from the smooth endoplasmic reticulum. The vacuoles were preferentially associated with stages 12, 13, 14, and 1 of the spermatogenic cycle. Additionally, at 4 weeks there was a significant decrease in the number of tubules in stages 7 and 13, and a concomitant increase in the percentage of tubules in stages 3, 5, and 6. By Week 5, most Golgi-phase and cap-phase spermatids were visibly affected, showing margination of nuclear chromatin, and were becoming dissociated from Sertoli cells. Frequent multinucleated giant cells were seen and electron microscopy of these cells suggested that they were derived from fused spermatocytes or spermatids. After 6 weeks, fewer giant cells were present, most tubules contained cellular debris, and many showed empty lumina encircled by a thin ring of cytoplasm near the basement membrane. Interstitial tissue appeared unaffected. These studies indicate that the Sertoli cell is probably an initial target for 2,5-HD action in the testis.  相似文献   
7.
The dual effect of L-proline on spreading depression in the chicken retina   总被引:1,自引:0,他引:1  
Evidence was presented for a glutamate agonistic effect of L-proline which promotes K+-based spreading depressions (SD) in chick retinas at relatively high concentrations (5 mM), in addition to an antagonistic effect which inhibits glutamate-based SDs at lower (2 mM) concentrations. Together these effects explain the observed biphasic effect of L-proline on the incidence of SD in the retina.  相似文献   
8.
Preparations of Amsacta moorei entomopox virions were obtained from virus-containing inclusions (VCI) by using a carbonate-thioglycolate solution (pH 10.7–11.5). The virions possessed a uniform coat (“halo”) surrounding the viral envelope and exhibited an RNA polymerase activity. The “halo” could be removed by prolonged exposure to the carbonate-thioglycolate solution. Virions obtained by this treatment, however, possessed low infectivity and no detectable RNA polymerase activity. Removal of the “halo” by trypsin resulted in virions which possessed RNA polymerase activity and relatively high infectivity.Preparations of particles with and without the “halo” were similar in percent DNA, protein per OD260, number of particles per OD260, and RNA polymerase activity. Particles without the “halo,” however, were less dense (1.262 g/cm3) in CsCl than those with the “halo” (1.282 g/cm3) and 15–45 times more infective.Parallel studies of “nonhaloed” Amsacta virions (trypsin-treated) and vaccinia virions showed that both viruses contained similar amounts of protein per OD260, but Amsacta virions contained only 36% of the DNA found in vaccinia.  相似文献   
9.
R F Ramig 《Virology》1983,127(1):91-99
A number of factors that affect genetic interaction during mixed infection with temperature-sensitive mutants of simian rotavirus SA11 have been examined. (1) Statistical analyses of recombination frequency (RF) indicated that (a) the variability noted in RF was not related to variations in experimental conditions and (b) a linear map of the mutations could not be drawn. (2) The wild phenotype of recombinant progeny was stable on passage. (3) Aggregates of progeny virus or heterozygous progeny virus particles did not contribute significantly to the observed RF. (4) RF increased in parallel with multiplicity of infection. (5) A maximal, or near maximal, RF was obtained at the earliest time significant recombinants could be detected. (6) Recombination was efficient at nonpermissive temperature. (7) Complementation did not occur or was inefficient. (8) Mutants from all recombination groups interfered with the growth of wild-type virus at both permissive and nonpermissive temperatures.  相似文献   
10.
介绍一种人体模型多通道电子语音解说系统的设计,该系统利用大规模 语音合成芯片的特点,建立了多路语音通道的手动寻址方式,实现了各路语音通过寻址电路和语音芯片的同步复位,完成了多路通道的录制与再生,因而提高了模型在医学教学中的价值。  相似文献   
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