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   7025篇
  免费   351篇
  国内免费   135篇
耳鼻咽喉   7篇
儿科学   133篇
妇产科学   13篇
基础医学   187篇
口腔科学   5篇
临床医学   1345篇
内科学   539篇
皮肤病学   54篇
神经病学   186篇
特种医学   230篇
外科学   129篇
综合类   1458篇
预防医学   1914篇
眼科学   11篇
药学   1119篇
  4篇
中国医学   162篇
肿瘤学   15篇
  2024年   10篇
  2023年   33篇
  2022年   61篇
  2021年   139篇
  2020年   135篇
  2019年   124篇
  2018年   108篇
  2017年   153篇
  2016年   201篇
  2015年   178篇
  2014年   389篇
  2013年   648篇
  2012年   539篇
  2011年   562篇
  2010年   457篇
  2009年   355篇
  2008年   422篇
  2007年   441篇
  2006年   372篇
  2005年   295篇
  2004年   240篇
  2003年   211篇
  2002年   160篇
  2001年   129篇
  2000年   110篇
  1999年   111篇
  1998年   76篇
  1997年   71篇
  1996年   50篇
  1995年   117篇
  1994年   60篇
  1993年   37篇
  1992年   28篇
  1991年   46篇
  1990年   35篇
  1989年   42篇
  1988年   45篇
  1987年   41篇
  1986年   29篇
  1985年   58篇
  1984年   33篇
  1983年   26篇
  1982年   19篇
  1981年   14篇
  1980年   17篇
  1979年   9篇
  1978年   18篇
  1977年   23篇
  1976年   13篇
  1974年   5篇
排序方式: 共有7511条查询结果,搜索用时 421 毫秒
1.
The presence of pesticides in the Israeli food supply is well documented but little is known about the risks posed by children's diets for potential exposures. We investigated potential exposures to food-borne pesticides in a sample of 301 urban Israeli children (2008–10). Data from a food frequency questionnaire, 24 hour food recall, and Israel's national pesticide monitoring program were used to estimate uptake factors for 26 compounds in 27 fruits and vegetables. A pilot risk assessment was performed and the findings were compared with the Israel Ministry of Health's 2012 pesticide risk assessment for the general population. The surveyed children had higher potential exposures than the general population for over one third of the compounds, and uptake factors exceeded the Acceptable Daily Intake in ten compounds. Methamidophos, exceeded the ADI at the 25th percentile and fenamiphos, iprodione, and oxydemethon methyl, exceeded the ADI at the 50 percentile. ADIs for several compounds were exceeded even though the residues detected were below the statutory limit. Improved monitoring, enforcement, and revision of the Maximum Residue Limit for certain food/pesticide pairs are indicated as is the need to incorporate data on children's actual food consumption in national risk assessments.  相似文献   
2.
目的:探讨急性一氧化碳(CO)中毒迟发性脑病患者血浆高迁移率族蛋白B1(HMGB1)的表达与预后。方法回顾性分析2012年1月—2015年1月该院接收的最终确诊为急性CO中毒迟发性脑病患者10例,另选取同时期内急性CO中毒患者10例以及健康体检者10例作为对照组。分别对各组患者的血浆HMGB1水平进行检测。另外,分别采用日常生活能力量表(ADL)、常识-记忆-注意测验(IMCT)、长谷川痴呆量表(HDS)分析急性CO中毒迟发性脑病患者血浆HMGB1水平变化及与量表评分之间的关系。结果 CO中毒迟发性脑病患者急性期血浆HMGB1水平为(14.23±10.32)ng/mL,明显高于恢复期的(7.93±4.99)ng/mL,差异有统计学意义(t=2.653,P<0.05);CO中毒迟发性脑病组急性期、恢复期血浆HMGBl水平与HDS以及ADL评分呈现显著正相关(r=0.610;r=0.605;r=0.607;r=0.610,P<0.05)。结论HMGBl参与急性CO中毒迟发性脑病的炎症反应前过程,且与HDS以及ADL评分呈正相关。  相似文献   
3.
《Annals of hepatology》2019,18(3):514-516
Gyromitra esculenta, also known as “false morel” is one of the most poisonous mushrooms. This species is found all over the world, growing in coniferous forest in early spring time. Common manifestation of poisoning includes gastrointestinal symptoms which include varied degrees of liver impairment.We describe three cases: acute liver injury, acute liver failure and acute-on-chronic liver failure due to G. esculenta poisoning. At admission patients presented with encephalopathy and features of liver failure. Two of them recovered completely following supportive management while the remaining patient who also had preexisting liver disease developed multiorgan failure and subsequently died.Although a rare occurrence, G. esculenta poisoning should be considered in the differential diagnosis of acute liver failure.  相似文献   
4.
急性一氧化碳中毒后迟发性脑病的临床表现和影像学特点   总被引:1,自引:0,他引:1  
目的探讨急性一氧化碳中毒后迟发性脑病的临床表现和影像学特点及其诊断价值。方法回顾性对23例急性一氧化碳中毒后迟发性脑病的临床表现和影像学特点进行归纳和分析。结果23例患者中智能障碍23例(100%),言语功能障碍17例(73.9%),另有共济失调精神障碍帕金森综合症及尿失禁等。头部CT和MRI主要表现为皮层下脑白质异常信号及基底节区或苍白球区异常信号,极少累及大脑皮质脑干和小脑。结论急性一氧化碳中毒后迟发性脑病的诊断主要依靠病史和临床症状,MRI比CT更有诊断价值。  相似文献   
5.
目的总结急性一氧化碳中毒后迟发性脑病(DEACMP)的有关临床特征。方法对本院2003年1月—2006年1月收治的46例DEACMP患者临床表现、影像学、脑电图、心电图、治疗及预后等进行回顾分析。结果46例均有意识障碍(主要表现为意识内容改变,少数表现为意识水平受损)持续时间(12.5±5.8)h,假愈期(10.5±6.2)d;36例有锥体外系功能障碍,部分病例有锥体系功能障碍,心电图检查异常率为43.5%(20/46),脑电图异常率为100%(32/32),CT异常率为69.6%(32/46),MR I 92%(23/25)。全组痊愈32例,好转13例,死亡1例。结论DEACMP主要表现为意识障碍、锥体外系和锥体系功能障碍,一经发生治疗较困难,致残率高。  相似文献   
6.
[目的]针对食物中毒事件追查源头的困难局面,探索1种新的食物中毒追查方法。[方法]通过分析各种常见类型食物中毒的潜伏期,结合各种实际情况,探讨存样食物保存的时间和方法。[结果]存样食物至少要保存24h。[结论]这种存样待检方法有其先进性,但仍存在不少问题,需进一步改进。  相似文献   
7.
CS_2作业工人血清脂质过氧化水平与LDH同功酶谱研究张文昌,连祥霖,张连娜,杨乃富(福建医学院劳动卫生学教研室,福州350004)结果表明,高接触水平组(浓度为10.42~46.54mg/m3或Σmg·年≥50)血清LPO含量与对照比较,显著性增高?..  相似文献   
8.
Pesticide regulation is examined in the context of Health Canada’s Pest Management Regulatory Agency’s assessment of the chlorophenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) for turf. 2,4-D is the most common herbicide used to kill weeds in grass.The medical literature does not uniformly indicate harms from herbicides. However, the balance of epidemiological research suggests that 2,4-D can be persuasively linked to cancers, neurological impairment and reproductive problems. These may arise from 2,4-D itself, from breakdown products or dioxin contamination, or from a combination of chemicals.Regulators rely largely on toxicology, but experiments may not replicate exposures from 2,4-D application to lawns because environmental breakdown products (eg, 2,4-dichlorophenol) may not accumulate and selected herbicides are possibly less contaminated. Dioxins are bioaccumulative chemicals that may cause cancer, harm neurological development, impair reproduction, disrupt the endocrine system and alter immune function. No dioxin analyses were submitted to the Pest Management Regulatory Agency, and the principal contaminants of 2,4-D are not among the 17 congeners covered in pesticide regulation. Independent assessment of all dioxins is needed, in tissues and in the environment.The 2,4-D assessment does not approach standards for ethics, rigour or transparency in medical research. Canada needs a stronger regulator for pesticides. Potentially toxic chemicals should not be registered when more benign solutions exist, risks are not clearly quantifiable or potential risks outweigh benefits. Until landscaping pesticides are curtailed nationally, local bylaws and Quebec’s Pesticide Code are prudent measures to protect public health. Physicians have a role in public education regarding pesticides.  相似文献   
9.
Aconitum species have been used in China as an essential drug in Traditional Chinese Medicine (TCM) for 2000 years. Reviewing the clinical application of Aconitum, their pharmacological effects, toxicity and detoxifying measures, herb–herb interactions, clinical taboos, famous herbal formulas, traditional and current herbal processing methods based upon a wide range of literature investigations serve as a case study to explore the multidisciplinary implications of botanicals used in TCM. The toxicological risk of improper usage of Aconitum remains very high, especially in countries like China, India and Japan. The toxicity of Aconitum mainly derives from the diester diterpene alkaloids (DDAs) including aconitine (AC), mesaconitine (MA) and hypaconitine (HA). They can be decomposed into less or non-toxic derivatives through Chinese traditional processing methods (Paozhi), which play an essential role in detoxification. Using Paozhi, the three main forms of processed aconite – Yanfuzi, Heishunpian and Baifupian – can be obtained (CPCommission, 2005). Moreover, some new processing techniques have been developed in China such as pressure-steaming. The current development of fingerprint assays, in particular HPLC, has set a good basis to conduct an appropriate quality control for TCM crude herbs and their ready-made products. Therefore, a stipulation for a maximum level of DDA content of Aconitum is highly desirable in order to guarantee the clinical safety and its low toxicity in decoctions. Newly developed HPLC methods have made the accurate and simultaneous determination and quantification of DDA content interesting.  相似文献   
10.
德国小蠊抗药性及其抗性衰退情况研究   总被引:4,自引:1,他引:3  
目的了解德国小蠊的抗药性及抗药性衰退情况.方法以点滴法测定德国小蠊对溴氰菊酯、敌敌畏、二氯苯醚菊酯、残杀威等的抗药性及抗药性衰退情况.结果现场品系分别为0.098、0.490、5.612、0.741ug/虫,正常饲养1年后抗性分别为0.086、0.232、3.412、0.317ug/虫,5年后抗性分别为0.008、0.123、0.410、0.0811ug/虫,LD50最高为二氯苯醚菊酯,1年后抗性衰退倍数范围为1.14~2.39,5年后抗性衰退倍数范围为3.98~13.69.结论具有高等抗性德国小蠊经实验室饲养5年后抗性基本衰退.  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