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   1180篇
  免费   86篇
  国内免费   17篇
耳鼻咽喉   46篇
儿科学   84篇
妇产科学   12篇
基础医学   100篇
口腔科学   27篇
临床医学   79篇
内科学   192篇
皮肤病学   27篇
神经病学   50篇
特种医学   144篇
外科学   132篇
综合类   137篇
预防医学   88篇
眼科学   4篇
药学   55篇
中国医学   39篇
肿瘤学   67篇
  2023年   7篇
  2022年   14篇
  2021年   24篇
  2020年   18篇
  2019年   16篇
  2018年   20篇
  2017年   15篇
  2016年   20篇
  2015年   29篇
  2014年   41篇
  2013年   43篇
  2012年   51篇
  2011年   50篇
  2010年   72篇
  2009年   62篇
  2008年   34篇
  2007年   39篇
  2006年   52篇
  2005年   35篇
  2004年   20篇
  2003年   29篇
  2002年   21篇
  2001年   20篇
  2000年   15篇
  1999年   24篇
  1998年   50篇
  1997年   61篇
  1996年   53篇
  1995年   38篇
  1994年   33篇
  1993年   31篇
  1992年   15篇
  1991年   10篇
  1990年   14篇
  1989年   30篇
  1988年   24篇
  1987年   21篇
  1986年   18篇
  1985年   15篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   10篇
  1980年   14篇
  1979年   7篇
  1977年   6篇
  1976年   7篇
  1966年   2篇
  1958年   4篇
  1957年   2篇
排序方式: 共有1283条查询结果,搜索用时 109 毫秒
21.
代谢综合症基线调查   总被引:1,自引:0,他引:1  
尹永英  李汝敏  沙蕾 《现代预防医学》2006,33(4):520-521,528
目的:通过对豫宛市30岁以上人群代谢综合症(MS)发病率的词查、统计和分析,旨在唤起人们对此病的重视和预防。方法:利用年度体检之机采用三级分组法对30岁以上人群进行有关MS指标的检测和统计,依据亚洲及我国体重指数标准及2004年中华医学会糖尿病分会诊断代谢综合症标准。共计调查人数3987人(男1981人,女2006人)。结果:30岁以上MS患病率,青年有10%~13%,中老年后可渐增至20%~30%。结论:MS是中老年多见的代谢异常疾病。已严重威胁着人们的生命健康。  相似文献   
22.
23.
Chesterman  CN; Owe-Young  R; Macpherson  J; Krilis  SA 《Blood》1986,67(6):1744-1750
Interactions between vascular endothelial cells and blood platelets have been investigated using a model microcirculation consisting of microcarrier beads colonized with human umbilical vein endothelial cells (HUVECs) and perfused with washed platelet suspensions. To simulate the effects of endothelial desquamation and exposure of subendothelium, fibrillar collagen in suspension was coinjected with the platelets. In this model, neither the passage of platelets alone nor collagen alone stimulated prostacyclin (PGI2) production by the HUVECs. Platelets activated by coinjection with collagen released thromboxane A2 (TXA2), and this was associated with the simultaneous production of PGI2 by the HUVECs. By means of double-isotope experiments with [3H]arachidonic acid (AA) incorporated into platelets and [14C]-AA into HUVECs, it was shown that all the PGI2 generated was derived from platelet AA and/or endoperoxides. This interpretation was strengthened by the finding that PGI2 production was not prevented by treatment of HUVECs with indomethacin followed by perfusion with collagen-stimulated platelets. AA metabolites in double-isotope label experiments were further characterized by reverse-phase chromatography, and it was shown that both cyclooxygenase and lipoxygenase products of the HUVECs were derived from platelet membrane lipid. Thrombin regularly produced transient PGI2 release, but showed rapid tachyphylaxis. Platelet-derived compounds including ADP, ATP, and platelet-activating factor (PAF) did not produce PGI2 release by HUVECs in this system. Thus, the transfer of AA and metabolites from collagen- stimulated platelets is likely to be the mechanism for PGI2 production in the context of minor degrees of endothelial desquamation.  相似文献   
24.
Transforming growth factor (TGF)- &#103 s in dentin matrix provide a pool of bioactive molecules, but association with latency-associated peptides (LAPs) may influence their activity. We investigated TGF- &#103 1, - &#103 2, and - &#103 3 LAP expression in sound and carious human teeth. Teeth were fixed and processed immediately following extraction prior to staining with rabbit polyclonal antibodies to the TGF- &#103 LAPs. A soluble dentin matrix fraction was prepared from dissected human dentin and sequential extraction of pulpal ECM was performed prior to purification. Fractions were Western blotted and probed with the LAP antibodies. All three LAPs were present in odontoblasts, cells of the pulp, and predentin; however, no staining of mineralized dentin matrix was seen. Similar patterns of expression were seen in carious tissue. Expression of TGF- &#103 LAPs in cells and pulpal matrix of healthy and carious teeth will be important in regulation of TGF- &#103 activity and may modulate the tissue response to injury.  相似文献   
25.
The objective is to estimate the risk of breast cancer in women who carry a deleterious BRCA1 or BRCA2 mutation, according to parental origin of mutation. We conducted a cohort study of women with a BRCA1 mutation (n = 1523) or BRCA2 mutation (n = 369) who had not been diagnosed with breast or ovarian cancer. For each woman, the pedigree was reviewed and the origin of the mutation was assigned as probable paternal or maternal. The hazard ratio (HR) for developing breast cancer in the follow‐up period was estimated for women with a paternal mutation compared to a maternal mutation. The risk of breast cancer was modestly higher in women with a paternal BRCA1 mutation compared to women with a maternal BRCA1 mutation (HR = 1.46; 95% CI = 0.99–2.16) but the difference was not significant (p = 0.06). The parental mutation origin did not affect the risk in women with a BRCA2 mutation. Our results are consistent with the hypothesis that there is an increased risk of breast cancer among women with a paternally inherited BRCA1 mutation compared to a maternally inherited mutation. However, the data are not sufficiently compelling to justify different screening recommendations for the two subgroups.  相似文献   
26.
Hereditary hemochromatosis (HH) is a common preventable disorder of iron overload that can result in liver cirrhosis and reduced lifespan. Most HH is due to homozygosity for the HFE p.C282Y substitution. We conducted a study of screening for p.C282Y in high schools where p.C282Y heterozygotes (CY) individuals were informed of their genotype by letter. We studied whether these individuals understood the implications of their genotype, whether this resulted in anxiety or reduced health perception and whether cascade testing was higher in families of CY than wild‐type homozygous (CC) individuals. We found 586 of 5757 (1 in 10) screened individuals were CY. One month after receiving their result, 83% correctly answered that they have one copy of p.C282Y. There was no adverse change in anxiety or health perception from prior to screening to 1 month after receiving results. Significantly more family members of CY individuals than CC individuals were informed about HH and had testing for HH. In conclusion, we found that informing CY individuals of their genotype does not increase anxiety and the implications are generally well understood. This leads to cascade testing in a minority of families. CY individuals should be informed of their genetic status when identified by population screening.  相似文献   
27.
目的:对蒙药苏格木勒-3水提物进行化学成分研究,构建较为全面的化学成分谱,为苏格木勒-3水提物有效物质基础研究奠定基础。方法:采用超高液相色谱串联四级杆飞行时间质谱(UPLC-Q-TOF-MS)技术,使用ESI离子源,通过mzCloud与mzVoult软件以及质谱裂解规律,并结合对照品及相关文献资料比对进行定性分析。结果:经过分析,从蒙药苏格木勒-3水提物中共鉴定出42个成分,主要包括氨基酸、酚酸类、黄酮类、内酯类、生物碱类及其他类等6类成分,并对各成分的药材来源进行归属。结论:本研究全面、快速、准确地分析了蒙药苏格木勒-3水提物的化学成分,为其药效物质基础和质量控制等研究奠定了基础。  相似文献   
28.
Molecular heterogeneity in acute leukemia lineage switch   总被引:1,自引:0,他引:1  
Six cases of acute leukemia that underwent lineage switch from acute lymphocytic leukemia to acute myelogenous leukemia are reported. The mean age of the patients was 24 years, time to conversion was 36 months, and survival after conversion was only 3 months. Of the three cases which showed abnormal metaphases at both diagnosis and conversion, two (cases 2, 5) showed related cytogenetic abnormalities, and the third showed (case 3) independent chromosomal changes. Molecular analysis for immunoglobulin heavy chain and T-cell receptor beta chain genes showed that five of the six cases had rearrangement of at least one of these lymphoid associated genes at conversion to acute myelogenous leukemia. The single case (case 3) in which there were no lymphoid gene rearrangements at conversion was also the only case in which independent karyotypic abnormalities at diagnosis and conversion were demonstrated. Our findings suggest that lineage switch can represent either relapse of the original clone with heterogeneity at the molecular level or the emergence of a second new leukemic clone without molecular heterogeneity.  相似文献   
29.
目的探讨宫内炎症暴露对早产儿固有免疫应答的影响。方法 2013年6月至2014年6月出生、胎龄35周的早产儿47例纳入本研究。依据胎盘病理检查结果,将早产儿分为宫内炎症阳性组和阴性组。采用Ficoll密度梯度离心法和贴壁黏附法分别获得脐血单个核细胞以及单核细胞。用内毒素(LPS,100 ng/ml)刺激单个核细胞12 h后,流式细胞术(PCR)检测CD14+单核细胞HLA-DR的表达量以及CD3+CD4+/CD3+CD8+的比例。用LPS(100 ng/ml)刺激单核细胞6 h后,Real-Time PCR检测单核细胞IL-1β、IL-6、IL-10、TNF-αm RNA表达量的变化。ELISA检测脐血以及单核细胞培养上清液中IL-1β、IL-6、IL-10和TNF-α水平。结果宫内炎症阳性组脐血血浆IL-6水平高于宫内炎症阴性组,差异有统计学意义(P=0.001)。LPS刺激后,两组单核细胞IL-1β、IL-6、IL-10、TNF-αm RNA表达量及培养上清液中蛋白水平均显著升高,与刺激前比较差异均有统计学意义(P0.05);但两组间比较差异均无统计学意义(P0.05)。LPS刺激后,宫内炎症阳性组CD14+单核细胞HLA-DR表达量显著降低,而宫内炎症阴性组则显著升高,与刺激前比较差异均有统计学意义(P0.05);且阳性组HLA-DR表达量显著低于阴性组(P=0.002)。结论宫内炎症暴露并不影响早产儿脐血单核细胞对LPS的应答反应水平,但可抑制单核细胞激活后主要抗原递呈受体的表达。  相似文献   
30.
BACKGROUND: The effects of aging on sympathetic nervous system and adrenomedullary outflow were estimated by the measurement of plasma norepinephrine (NE) and epinephrine (EPI) responses to yohimbine and clonidine in healthy young and healthy older subjects. METHODS: Yohimbine (0.65 mg/kg), clonidine (5 microg/kg), and placebo were administered on separate days in random order to 5 healthy older men (age 74 +/- 1 years) and 18 healthy young men (age 26 +/- 1 years). NE and EPI were measured by radioenzymatic assay in plasma samples obtained before and 30, 60, and 90 minutes after drug administration. RESULTS: Plasma NE increases after yohimbine were greater in older men than in young men. but plasma NE decreases following clonidine did not differ between groups. Plasma NE and systolic blood pressure were higher in older men than in young men at baseline but no longer differed 90 minutes after clonidine. Plasma EPI increases after yohimbine and decreases after clonidine did not differ between groups. CONCLUSIONS: These results suggest increased sympathetic nervous system outflow in human aging that is not a function of reduced responsiveness of alpha-2 adrenoreceptor-mediated feedback inhibition.  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