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   21246篇
  免费   1126篇
  国内免费   881篇
耳鼻咽喉   166篇
儿科学   230篇
妇产科学   408篇
基础医学   3571篇
口腔科学   679篇
临床医学   2364篇
内科学   1871篇
皮肤病学   323篇
神经病学   1953篇
特种医学   307篇
外国民族医学   1篇
外科学   1528篇
综合类   4196篇
现状与发展   1篇
一般理论   2篇
预防医学   1853篇
眼科学   691篇
药学   1554篇
  11篇
中国医学   909篇
肿瘤学   635篇
  2024年   25篇
  2023年   145篇
  2022年   288篇
  2021年   384篇
  2020年   409篇
  2019年   386篇
  2018年   369篇
  2017年   430篇
  2016年   557篇
  2015年   524篇
  2014年   1090篇
  2013年   1356篇
  2012年   1028篇
  2011年   1207篇
  2010年   1004篇
  2009年   976篇
  2008年   1023篇
  2007年   1136篇
  2006年   1106篇
  2005年   1040篇
  2004年   931篇
  2003年   852篇
  2002年   736篇
  2001年   586篇
  2000年   489篇
  1999年   493篇
  1998年   404篇
  1997年   335篇
  1996年   324篇
  1995年   348篇
  1994年   271篇
  1993年   216篇
  1992年   256篇
  1991年   252篇
  1990年   215篇
  1989年   194篇
  1988年   187篇
  1987年   152篇
  1986年   167篇
  1985年   220篇
  1984年   199篇
  1983年   139篇
  1982年   171篇
  1981年   151篇
  1980年   138篇
  1979年   98篇
  1978年   92篇
  1977年   49篇
  1976年   43篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
This study examined the mitogenic response to keratinocyte growth factor (KGF) of normal and tumour-derived human oral keratinocytes in which the degree of cellular differentiation was known and in contiguous fibroblast cultures derived from the malignant epithelial cultures. Keratinocytes, but not fibroblasts, were stimulated by KGF. There by demonstrating epithelial target cell specificity of the ligand. KGF-induced stimulation of the tumour-derived keratinocytes cultured in the absence of the 3T3 fibroblast support broadly correlated with the degree of cellular differentiation; well-differentiated keratinocytes were stimulated more by KGF than their less differentiated counterparts. Malignant oral keratinocytes expressed KGF cell surface receptors (KD 451-709 pM; receptors/cell 2306-413645), but KGF receptor mRNA did not correlate with either KGF-induced mitogenesis or the degree of epithelial cell differentiation. When the tumour-derived keratinocytes were cultured in the presence of 3T3 fibroblasts, the mitogenic response to KGF was comparable to normal epithelial cells. The results suggest that KGF-mediated growth stimulation may not be significant in providing a selective advantage for the growth of malignant keratinocytes.  相似文献   
32.
羊水细胞培养技术研究   总被引:1,自引:0,他引:1  
王世雄  胡琴 《上海医学》1992,15(9):527-530
  相似文献   
33.
Summary The adherence, growth, and electrophysiologic properties of guinea pig gastric mucous epithelial cells were investigated using porous membrane filters. We also tested three commercially available Ussing-type chambers that were designed to be used with the various porous membrane supports. Overall, the 0.45-µm Falcon-Cyclopore porous membrane was found to be very favorable for the consistent attachment and growth of our cells. This same filter also gave good results in the detection of periodic acid Schiff-positive mucous glycoprotein and Nile red neutral lipid fluorescence in the gastric mucous cells. Our cells grew poorly on collagen-coated Costar-Snapwells and Millipore Millicell-CM porous filters. For measurement of transepithelial potential difference resistance, and short-circuit current, the Costar-Snapwell with the Costar-Snapwell Diffusion-chamber system was superior in design and operation when compared to the Costar Transwell-COL, Falcon-Cyclopore, or Anotec-Anocell porous inserts used with conventional Ussing-chambers. The gastric mucous cells grew best on ICN-Cellagen membranes, but these filters routinely detached from their plastic holder and therefore could not be used for Ussing-chamber studies. The large 24.5-mm, 0.40-µm pore size Costar-Transwell-COL and the 24.1-mm, 0.45-µm Falcon-Cyclopore membranes gave good results when used in a modified horizontal-chamber for microelectrode analysis of membrane potentials and resistances of the gastric mucous cell monolayers.  相似文献   
34.
硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用   总被引:8,自引:1,他引:7  
研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。  相似文献   
35.
目的 研究补肾活血方药对慢性再生障碍性贫血 (CAA)患者骨髓细胞体外增殖的影响 ,探讨其治疗CAA的机制。方法 采用细胞培养 ,光镜下观察补肾活血中药作用于CAA患者骨髓细胞后的形态学 ;3 H TdR掺入和液体闪烁技术方法 ,检测补肾活血中药对CAA患者骨髓细胞的增殖变化。结果 加入补肾活血中药组 ,CAA患者骨髓细胞培养第 4 8小时见细胞丛明显增多 ,72h见大量集落形成 ;3 H TdR掺入法显示 ,补肾活血中药组骨髓细胞的增殖 ,以每孔 75g L最有效。在 5 0~ 10 0g L范围内 ,与对照组比较差异有显著性 (P <0 .0 1) ;2 5g L和 12 5g L组与对照组比较差异无显著性 (P <0 .0 5 )。结论 补肾活血方药在体外有促进CAA患者骨髓细胞增殖的作用 ,为补肾活血中药治疗CAA提供了实验与理论依据  相似文献   
36.
文章对组织文化调查问卷的认知部分进行了分析研究,并针对出现的问题,提出医院文化建设和管理方面的建议。  相似文献   
37.
本实验对培养中的大鼠胎胰胰岛组织及其移植后的形态功能进行了观察。结果表明,大鼠胎胰经短期培养,不仅内分泌胰岛β细胞的活力保存良好,而且胰外分泌腺泡大大减少以致消失。21只糖尿病大鼠,同种移植经过7天培养的胎胰胰岛,未用免疫抑制剂,术后糖尿病缓解率76.2%。  相似文献   
38.
Astrocytes, with their many functions in producing and controlling the environment in the brain, are of great interest when it comes to studying regeneration after injury and neurodegenerative diseases such as in grafting in Parkinson's disease. This study was performed to investigate astrocytic guidance of growth derived from dopaminergic neurons using organotypic cultures of rat fetal ventral mesencephalon. Primary cultures were studied at different time points starting from 3 days up to 28 days. Cultures were treated with either interleukin-1 beta (IL-1 beta), which has stimulating effects on astrocytic proliferation, or the astrocytic inhibitor cytosine arabinoside (Ara-C). Tyrosine hydroxylase (TH)-immunohistochemistry was used to visualize dopaminergic neurons, and antibodies against glial fibrillary acidic protein (GFAP) and S100 beta were used to label astrocytes. The results revealed that a robust TH-positive nerve fiber production was seen already at 3 days in vitro. These neurites had disappeared by 5 days. This early nerve fiber outgrowth was not guided by direct interactions with glial cells. Later, at 7 days in vitro, a second wave of TH-positive neuritic outgrowth was clearly observed. GFAP-positive astrocytic processes guided these neurites. TH-positive neurites arborized overlying S100 beta-positive astrocytes in an area distal to the GFAP-positive astrocytic processes. Treatment with IL-1 beta resulted in an increased area of TH-positive nerve fiber network. In cultures treated with Ara-C, neither astrocytes nor outgrowth of dopaminergic neurites were observed. In conclusion, this study shows that astrocytes play a major role in long-term dopaminergic outgrowth, both in axonal elongation and branching of neurites. The long-term nerve fiber growth is preceded by an early transient outgrowth of dopamine neurites.  相似文献   
39.
同型半胱氨酸对胚胎海马神经元细胞的影响   总被引:1,自引:1,他引:0  
目的 观察同型半胱氨酸(homocysteine,HCY)对海马神经元细胞分化和增殖的作用机理。方法 采用大鼠胚胎海马神经元细胞进行体外培养。观察不同浓度的HCY(0.01、0.1、1.0、10.0、100.0)mmol/L对细胞分化和增殖的影响。结果 随着剂量的增加.同型半胱氨酸对胚胎海马神经元细胞分化和增殖具有抑制作用,并用流式细胞术分析证明对脂质过氧化(LPO)的影响而使得神经元蛋白质含量增高。结论 同型半胱氨酸可抑制胚胎海马神经元细胞分化和增殖的影响,HCY可能在导致神经管畸形的过程起着重要作用。  相似文献   
40.
Swabbing the urethrae of men has been the traditional approach for collecting specimens for detection of Chlamydia trachomatis . Recently, however, urine testing using enzyme immunoassay has yielded promising results. A total of 105 patients attending the Andrology Clinic at Ga Rankuwa Hospital, Medunsa were included in the study. These patients were asymptomatic and had no urethral discharge. Three endo-urethral swabs and first-catch urine were collected fiom each patient. The urethral swabs were used for enzyme immunoassay (EIA) (IDEIA 111), tissue culture and direct immonufluorescent antibody (DFA) test (IMAGEN) to detect C. trachomatis . In addition about 15–30 ml of first-catch urine, or urine collected at least 2h after the previous micturition, was collected for each patient for EIA testing. Fifteen (14.3%) of 105 patients were positive on urethral swab EIA, in comparison with the DFA test in which 14 (13.3%) were positive. Eight (7.8%) were positive in tissue culture. Urine EIA was positive in 17 (16.2%) patients, of whom five (4.8%) were positive in urine EIA only. All EIA positive urines were confirmed by DFA. We recommend that first-catch urine or urine collected at least 2h after the previous micturition in infertile males may be considered a suitable alternative to urethral swab for chlamydial diagnosis because it is noninvasive and nontraumatic.  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