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   879篇
  免费   13篇
  国内免费   9篇
耳鼻咽喉   2篇
儿科学   7篇
妇产科学   8篇
基础医学   37篇
口腔科学   47篇
临床医学   26篇
内科学   9篇
皮肤病学   7篇
神经病学   39篇
特种医学   10篇
外科学   14篇
综合类   51篇
预防医学   422篇
眼科学   2篇
药学   212篇
中国医学   7篇
肿瘤学   1篇
  2021年   10篇
  2020年   14篇
  2019年   8篇
  2018年   7篇
  2017年   13篇
  2016年   18篇
  2015年   17篇
  2014年   32篇
  2013年   62篇
  2012年   43篇
  2011年   78篇
  2010年   44篇
  2009年   58篇
  2008年   73篇
  2007年   59篇
  2006年   40篇
  2005年   50篇
  2004年   40篇
  2003年   15篇
  2002年   18篇
  2001年   9篇
  2000年   14篇
  1999年   13篇
  1998年   13篇
  1997年   13篇
  1996年   13篇
  1995年   14篇
  1994年   11篇
  1993年   9篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   4篇
  1986年   6篇
  1985年   6篇
  1984年   8篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1980年   3篇
  1978年   6篇
  1977年   3篇
  1976年   6篇
  1975年   6篇
  1974年   3篇
  1973年   4篇
  1972年   2篇
  1971年   3篇
排序方式: 共有901条查询结果,搜索用时 0 毫秒
1.
Objective The present study aims to investigate the concentrations of Hg and its aspects methyl mercury(Me-Hg) and inorganic mercury(I-Hg) in the biological samples(BSs) of fluorescent lamp industries workers(FLIWs).Methodology Different BSs including red blood cells(RBCs),plasma,urine,hair and nails were collected from the workers exposed to Hg and unexposed persons were selected as control group to measure both the T-Hg concentration as well as its species in different biological samples through quantitative analysis.Health data was collected through questionnaire survey.Results The mean concentrations of T-Hg(31.9 μg/L),Me-Hg(27.7 μg/L),and I-Hg(5.36 μg/L) in RBCs were found significantly(P 0.001) higher among the workers(n = 40) as compared to the control group(n = 40).Similarly the mean Hg concentrations in plasma,urine,hair and nails were also significantly higher among the workers than the control group.The statistical relation between Hg concentration and demographic characteristics observed that workers experience and fish consumption has increased the Hg concentration while age,weight and smoking found no significant effect on Hg concentration in the BSs.Conclusion The study observed that the workers were highly exposed to high concentration of Hg and they are at a high health risk.  相似文献   
2.
松花江汞污染治理后沿江渔民发汞调查   总被引:1,自引:0,他引:1  
调查结果表明,沿江渔民发汞均值为2.25μg/g,与对照点相比差异显著(P<0.01),其中扶余一松江段渔民发汞均值2.54μg/g,高于其他各江段;30~40岁年龄组渔民发汞值超过正常值者占45%,比其他各年龄组多;在调查的1195人中有25名发汞值超过10μg/g,其中18人发甲基汞含量超过5μg/g。  相似文献   
3.
无机汞对男工内分泌和大鼠睾丸微量元素的影响   总被引:1,自引:0,他引:1  
应用放射免疫分析法(RIA)和流行病学调查,对40名接触汞和40名非接触汞男工进行了血清甲状腺激素、性激素水平和生殖功能的测定。结果表明,接触组男工的阳萎、早泄、性欲减退发生率和男工妻子的早产、自然流产发生率以及血清甲状腺激素(FT3和FT4)含量明显增多,每周性交次数和血清睾酮含量显著减少。上述各项与对照组比较差异非常显著。应用火焰光度法,对氯化汞染毒后大鼠睾丸组织的微量元素进行测定,实验组的锌值明显降低。结果提示氯化汞能够影响甲状腺激素、睾酮和锌元素水平。  相似文献   
4.
本研究采用亚急性汞中毒肾损害的大鼠模型,探讨了汞中毒时血、肾和尿中碱性磷酸酶(ALP)活性的变化关系。结果表明,大鼠肾匀浆中 ALP活性明显低于对照组,尿 ALP活性则显著增加。ALP 活性降低的部位在肾近曲小管。体外实验未发现氯化汞对肾、尿ALP 具有直接抑制作用或激活作用。尿中ALP 活性的增高是汞引起的肾小管上皮细胞损伤所致。它可作为汞中毒肾损害的一个观察指标。  相似文献   
5.
Dietary selenium (Se) status is inversely related to vulnerability to methylmercury (MeHg) toxicity. Mercury exposures that are uniformly neurotoxic and lethal among animals fed low dietary Se are far less serious among those with normal Se intakes and are without observable consequences in those fed Se-enriched diets. Although these effects have been known since 1967, they have only lately become well understood. Recent studies have shown that Se-enriched diets not only prevent MeHg toxicity, but can also rapidly reverse some of its most severe symptoms. It is now understood that MeHg is a highly specific, irreversible inhibitor of Se-dependent enzymes (selenoenzymes). Selenoenzymes are required to prevent and reverse oxidative damage throughout the body, particularly in the brain and neuroendocrine tissues. Inhibition of selenoenzyme activities in these vulnerable tissues appears to be the proximal cause of the pathological effects known to accompany MeHg toxicity. Because Hg's binding affinities for Se are up to a million times higher than for sulfur, its second-best binding partner, MeHg inexorably sequesters Se, directly impairing selenoenzyme activities and their synthesis. This may explain why studies of maternal populations exposed to foods that contain Hg in molar excess of Se, such as shark or pilot whale meats, have found adverse child outcomes, but studies of populations exposed to MeHg by eating Se-rich ocean fish observe improved child IQs instead of harm. However, since the Se contents of freshwater fish are dependent on local soil Se status, fish with high MeHg from regions with poor Se availability may be cause for concern. Further studies of these relationships are needed to assist regulatory agencies in protecting and improving child health.  相似文献   
6.
低剂量甲基汞在小鼠体内分布及其对细胞周期进程的影响   总被引:3,自引:0,他引:3  
连续90天饮用含甲基汞浓度为1/1000LD50、1/100LD50、1/50LD50和1/10LD50的自来水的雄性昆明小鼠,各脏器中总汞含量均高于对照组(P<0.05~0.005),并且随着染毒剂量增加,脏器中总汞含量也随之增高。同时采用FACScan流式细胞仪和“CellFIT”软件分析脾细胞周期进程,发现除1/1000LD50剂量组外,其余各剂量组从Go/G1时相进入S时相的脾细胞百分数均明显高于对照组(P<0.05),与染毒剂量呈明显正相关。表明连续经口摄入低剂量甲基汞小鼠脾细胞周期进程加快,细胞DNA复制增强。  相似文献   
7.
The Pocone gold minings are situated in the Bento Gomes River Basin, at the border of the Pantanal of Mato Grosso. Gold-bearing quartz veins are removed from the subsoils, milled with water, centrifuged and the heavier fraction is subsequently mixed with mercury for gold separation. The gold mining activities caused a very intensive landscape change, threatening many environmental processes like sediment control and storage and recycling capacity of mercury. Cold Vapor Atomic Fluorescence System (CVAFS) was used to determinate total mercury in water, suspended material and sediments from Bento Gomes River, sampled monthly for 1 year. Apart from the fact that mercury concentrations are low in water and bottom sediments, they are slightly higher in relation to background levels measured in the area. The concentration in suspended material is also lower than other rivers with gold mining activities, but the floodplains of the Bento Gomes River act as mercury sinks. Therefore, the discharge of mercury into the Pantanal floodplain should be avoided, in spite of actual contamination of the system being very low.  相似文献   
8.
The distribution in pregnant C57BL mice (day 18 of gestation) of intravenously administered cadmium (Cd) chloride and mercury (Hg) chloride (0.75 mol/kg b.w.) was studied, with or without previous dithiocarbamate pretreatment. Diethyldithiocarbamate (DEDTC), disulfiram, or thiram (2×1 mmol/kg b.w.) or vehicle (gelatine) alone, were given by gavage 2 h before and immediately after injection of the metals. The mice were sacrificed 4 and 24 h later and subjected to autoradiography or impulse counting of excised organs.All the dithiocarbamates increased the concentration of both Cd and Hg in brain and most other maternal organs. While DEDTC and thiram, in that order, strongly increased Cd concentrations in whole fetuses (around 17-fold at 4 h) and all fetal organs measured, disulfiram caused a decrease in fetal Cd concentrations. For Hg, all the dithiocarbamates substantially decreased fetal levels. Disulfiram, for example, decreased Hg levels by a factor of 5. The 24 h values confirmed those at 4 h both elements, although the differences between control and treatment groups were less pronounced.Although the results suggest the formation of lipid-soluble metal-dithiocarbamate complexes in vivo (e.g., increased concentration in brain), this does not necessarily lead to increased fetal levels of the metals. The increased levels of Cd after thiram and DEDTC pretreatment, however, indicate a risk for higher Cd fetotoxicity. It is likely that Cd is released in fetal cells following metabolism of the dithiocarbamate moiety of the complex.  相似文献   
9.
用837-49μmol/L 含汞水饲养大鼠8 周,复制出慢性汞中毒模型,然后分别自由饮用含维生素C6812-76μmol/L 的利康饮和ip 125mg/kg 二巯基丙磺酸钠(DMPS)3 周,探讨利康饮和DMPS 对慢性汞中毒大鼠尿汞排泄和脂质过氧化损害的影响。结果发现,慢性汞中毒引起血清、肝、脑和肾还原型谷胱甘肽(GSH) 含量显著降低,血清、肝、脑和肾丙二醛( MDA) 含量、尿蛋白含量及尿碱性磷酸酶(AKP) 活性显著升高;利康饮可显著增加尿汞排泄和血清维生素C 含量,并使慢性汞中毒引起的血清、肝、脑和肾GSH 含量显著回升,血清、脑和肾MDA 含量、尿蛋白含量及尿AKP 活性显著回降;DMPS 虽有明显促进尿汞排泄效果和使血清MDA 含量显著回降的作用,但对慢性汞中毒引起的其它脂质过氧化损害指标影响不明显。结果表明,刺梨利康饮具有一定排汞效果,并对慢性汞中毒引起的机体抗氧化功能降低和脂质过氧化损害具有明显拮抗作用。  相似文献   
10.
We have used patch-clamp techniques to study the effect of the sulfhydryl group oxidizing agents mercury and thimerosal on calcium-activated nonselective cation channels from brown adipose tissue. 100 nmol/l mercury and 50 mol/l thimerosal induced a complete block. Blockade could be reversed by reduction of the mercaptide by dithiotreitol (DTT). Mercury was found to be the most potent blocker (IC50-value 21×10–9 mol/l), whereas thimerosal (IC50-value 1.5×10–6 mol/l) was as effective as 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC). The DCDPC effect, however, could not be reversed by DTT, indicating different blocking mechanisms. It is concluded that SH-groups are involved in gating of the calcium-activated nonselective channel.  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