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   58916篇
  免费   6721篇
  国内免费   4040篇
耳鼻咽喉   528篇
儿科学   688篇
妇产科学   532篇
基础医学   5378篇
口腔科学   1415篇
临床医学   7648篇
内科学   7105篇
皮肤病学   635篇
神经病学   2459篇
特种医学   2185篇
外国民族医学   22篇
外科学   5286篇
综合类   12281篇
现状与发展   21篇
一般理论   9篇
预防医学   5222篇
眼科学   1377篇
药学   7322篇
  92篇
中国医学   5568篇
肿瘤学   3904篇
  2024年   426篇
  2023年   1318篇
  2022年   3354篇
  2021年   4164篇
  2020年   3187篇
  2019年   2226篇
  2018年   2271篇
  2017年   2345篇
  2016年   2014篇
  2015年   2983篇
  2014年   3567篇
  2013年   3632篇
  2012年   5068篇
  2011年   5301篇
  2010年   3729篇
  2009年   3000篇
  2008年   3300篇
  2007年   3144篇
  2006年   2834篇
  2005年   2326篇
  2004年   1732篇
  2003年   1736篇
  2002年   1469篇
  2001年   1085篇
  2000年   742篇
  1999年   601篇
  1998年   358篇
  1997年   295篇
  1996年   214篇
  1995年   202篇
  1994年   178篇
  1993年   124篇
  1992年   141篇
  1991年   97篇
  1990年   115篇
  1989年   65篇
  1988年   70篇
  1987年   63篇
  1986年   47篇
  1985年   38篇
  1984年   27篇
  1983年   14篇
  1982年   10篇
  1981年   12篇
  1979年   18篇
  1978年   6篇
  1977年   4篇
  1976年   4篇
  1974年   5篇
  1966年   4篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Lian-Niang L  Hung X  Rui T 《Planta medica》1985,51(4):297-300
Ten dibenzocyclooctadiene lignans were obtained from the ethereal soluble fraction of the dried roots and stems of KADSURA COCCINEA. Two of them were new compounds, named kadsutherin ( 8) and isokadsuranin ( 10). Their structures were elucidated on the basis of chemical and spectral analysis.  相似文献   
62.
63.
Radiation therapy is widely used in the treatment of tumor diseases, but it can also cause serious damage to the body, so it is necessary to find effective nutritional supplements. The main purpose of this study is to evaluate the protective effect of whey hydrolysate peptides (WHPs) against 60Coγ radiation damage in mice and explore the mechanism. BALB/c mice were given WHPs by oral gavage administration for 14 days. Then, some mice underwent a 30-day survival test after 8 Gy radiation, and other mice received 3.5 Gy radiation to analyze the changes in body weight, hematology and bone marrow DNA after three and 14 days. In addition, through further analysis of the level of oxidative stress and intestinal barrier function, the possible mechanism of the radioprotective effect of WHPs was explored. The study found WHPs can prolong survival time, restore body weight, and increase the number of peripheral blood white blood cells and bone marrow DNA content in irradiated mice. In addition, WHPs can significantly improve the antioxidant capacity, inhibit pro-inflammatory cytokines and protect the intestinal barrier. These results indicate that WHPs have a certain radioprotective effect in mice, and the main mechanism is related to reducing oxidative damage.  相似文献   
64.
Diabetes is the seventh leading cause of death in United States. Dietary intake and behaviors are essential components of diabetes management. Growing evidence suggests dietary components beyond carbohydrates may critically impact glycemic control. Assessment tools on mobile platforms have the ability to capture multiple aspects of dietary behavior in real-time throughout the day to inform and improve diabetes management and insulin dosing. The objective of this narrative review was to summarize evidence related to dietary behaviors and composition to inform a mobile image-based dietary assessment tool for managing glycemic control of both diabetes types (type 1 and type 2 diabetes). This review investigated the following topics amongst those with diabetes: (1) the role of time of eating occasion on indicators of glycemic control; and (2) the role of macronutrient composition of meals on indicators of glycemic control. A search for articles published after 2000 was completed in PubMed with the following sets of keywords “diabetes/diabetes management/diabetes prevention/diabetes risk”, “dietary behavior/eating patterns/temporal/meal timing/meal frequency”, and “macronutrient composition/glycemic index”. Results showed eating behaviors and meal macronutrient composition may affect glycemic control. Specifically, breakfast skipping, late eating and frequent meal consumption might be associated with poor glycemic control while macronutrient composition and order of the meal could also affect glycemic control. These factors should be considered in designing a dietary assessment tool, which may optimize diabetes management to reduce the burden of this disease.  相似文献   
65.
目的:认识多发伤中骨折的主要特点,探讨内固定在救治中的意义。方法:回顾1994-08~1999-08间手术救治多发伤66例,对其161处骨折中的98处进行了“仿AO技术”有关方法内固定。结果:骨折均满意愈合;涉及骨折关节51个,功能恢复满意率为96.08%。结论:在多发伤中,骨折、合并伤与并发症远较“一般骨折”复杂、严重;有效固定骨折是一种重要的救命措施;内固定手术应争取在伤后24h进行,但如受条件制约,伤后1-3wk内手术也可获得满意效果;仿AO技术中的某些方法,如拉力螺钉、张力带钢丝及自动加压钢板等,用于内固定可使骨折获得卓有成效的稳定性。  相似文献   
66.
目的 :探讨导电聚吡咯膜技术对大鼠肺Ⅱ型细胞体外生长的作用。方法 :采用四甲基偶氮唑盐比色法测定比较导电聚吡咯膜组和常规培养组大鼠肺Ⅱ型细胞的生长和增殖情况。结果 :培养 3~ 5d后两组OD值有显著差异 (P <0 .0 5 )。结论 :常规培养条件下的大鼠肺Ⅱ型细胞在体外生长时间约 2~ 3d ,导电聚吡咯膜可以将肺Ⅱ型细胞体外生长时间延长至 5d。  相似文献   
67.
目的:探讨慢性乙型肝炎患者肝组织中FasL表达与血清可溶性FasL水平的关系。方法:用免疫组化方法检测60例慢性乙型肝炎患者肝穿组织FasL的表达,同时用酶联免疫吸附试验检测血清可溶性FasL。结果:重度慢性乙型肝炎患者血清中sFasL水平>中度>轻度,各组间差异有显著意义(P<0.01);慢性乙型肝炎患者肝组织FasL表达的程度和血清sFasL水平与肝组织病变的活动性一致。结论:(1)肝组织炎症程度加重,肝组织FasL抗原的表达增强,同时血清中sFasL水平升高;(2)Fas介导的肝细胞凋亡在慢性乙型肝炎的发病机制中起重要作用,抑制肝细胞Fas表达有助于减轻肝细胞损伤程度。  相似文献   
68.
端粒酶及nm23的表达与胃腺癌预后的关系探讨   总被引:1,自引:0,他引:1  
目的 :探讨端粒酶和nm2 3癌基因蛋白表达与胃癌根治术后复发及预后的关系。方法 :采用端粒酶原位分子杂交技术及免疫组化S P法分别对 4 5例原发性胃腺癌组织中端粒酶的活性及nm2 3进行检测 ,并结合内镜及随访资料进行分析。结果 :胃腺癌端粒酶阳性表达率及nm2 3低表达率在有淋巴结转移组显著高于无淋巴结转移组 ;在术后 5年内复发者中显著高于无复发者。虽然随着胃腺癌分化程度的降低及浸润深度的增加 ,端粒酶活性及nm2 3低表达呈增强趋势 ,但其差异无统计学意义。结论 :胃腺癌组织中端粒酶的活性表达及nm2 3的低表达与淋巴结转移及术后复发显著相关 ,两者的表达变化对判断胃癌术后复发及预后判断有重要临床意义  相似文献   
69.
Germplasm cryopreservation and expansion of gonocytes/prospermatogonia or spermatogonial stem cells (SSCs) are important; however, it's difficult in cattle. Since inhibitors of Mek1/2 and Gsk3β (2i) can enhance pluripotency maintenance, effects of 2i-based medium on the cultivation of bovine prospermatogonia from the cryopreserved tissues were examined. The testicular tissues of newborn bulls were well cryopreserved. High mRNA levels of prospermatogonium/SSC markers (PLZF, GFRα-1) and pluripotency markers (Oct4/Pouf5, Sox2, Nanog) were detected and the PLZF+/GFRα-1+ prospermatogonia were consistently identified immunohistochemically in the seminiferous cords. Using differential plating and Percoll-based centrifugation, 41.59% prospermatogonia were enriched and they proliferated robustly in 2i medium. The 2i medium boosted mRNA abundances of Pouf5, Sox2, Nanog, GFRα-1, PLZF, anti-apoptosis gene Bcl2, LIF receptor gene LIFR and enhanced PLZF protein expression, but suppressed mRNA expressions of spermatogonial differentiation marker c-kit and pro-apoptotic gene Bax, in the cultured prospermatogonia. It also alleviated H2O2-induced apoptosis of the enriched cells and decreased histone H3 lysine (K9) trimethylation (H3K9me3) and its methylase Suv39h1/2 mRNA level in the cultured seminiferous cords. Overall, 2i medium improves the cultivation of bovine prospermatogonia isolated from the cryopreserved testes, by inhibiting Suv39h1/2-mediated H3K9me3 through Mek1/2 and Gsk3β signalling, evidencing successful cryopreservation and expansion of bovine germplasm.  相似文献   
70.
The blood–testis barrier (BTB) of Sertoli cells (SCs) is an important biological barrier that maintains spermatogenesis and provides a favourable microenvironment for spermatogenesis. However, heat stress can directly damage the BTB structural proteins of testicular SCs, leading to dyszoospermia. Wuzi Yanzong Pills (WYP) is a traditional Chinese medicine formula used to treat male reproductive diseases. However, whether WYP could ameliorate heat stress injury in primary SCs extracted from rat testes and BTB proteins remains unknown. Here, treatment with WYP (low, medium and high dose) increased the SC viability and the proliferation of cell antigen Ki67 significantly. Additionally, it promoted SC maturation, which presented in the form of increased androgen receptors (ARs) and decreased cytokeratin 18 (CK-18) in three WYP dose groups. WYP upregulated BTB proteins such as zonula occludens 1 (ZO-1) and occludin across all WYP groups and decreased phosphorylated Akt (p-Akt) in the middle and high-dose groups; however, ZO-1 and occludin recovery were reduced with the presence of Akt inhibitor in WYP groups. WYP improved SC viability and proliferation, and ameliorated dedifferentiation and BTB-proteins damaged by heat stress via Akt signalling. The findings present theoretical support for the effects of WYP in the management of dyszoospermia and male infertility.  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