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   15764篇
  免费   1253篇
  国内免费   367篇
耳鼻咽喉   25篇
儿科学   151篇
妇产科学   78篇
基础医学   1210篇
口腔科学   403篇
临床医学   1238篇
内科学   2166篇
皮肤病学   502篇
神经病学   790篇
特种医学   762篇
外科学   583篇
综合类   1730篇
一般理论   2篇
预防医学   4435篇
眼科学   119篇
药学   2079篇
  3篇
中国医学   892篇
肿瘤学   216篇
  2023年   131篇
  2022年   258篇
  2021年   569篇
  2020年   460篇
  2019年   427篇
  2018年   414篇
  2017年   435篇
  2016年   506篇
  2015年   527篇
  2014年   913篇
  2013年   1117篇
  2012年   1027篇
  2011年   1347篇
  2010年   904篇
  2009年   786篇
  2008年   762篇
  2007年   795篇
  2006年   641篇
  2005年   546篇
  2004年   526篇
  2003年   435篇
  2002年   388篇
  2001年   385篇
  2000年   278篇
  1999年   253篇
  1998年   254篇
  1997年   213篇
  1996年   198篇
  1995年   157篇
  1994年   170篇
  1993年   131篇
  1992年   140篇
  1991年   122篇
  1990年   91篇
  1989年   103篇
  1988年   82篇
  1987年   79篇
  1986年   52篇
  1985年   105篇
  1984年   85篇
  1983年   71篇
  1982年   78篇
  1981年   56篇
  1980年   55篇
  1979年   69篇
  1978年   44篇
  1977年   35篇
  1976年   33篇
  1975年   25篇
  1973年   38篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
61.
利用电渗析和离子交换柱除去原水中的各种杂质可得到去离子水.而去离子水的质量直接决定了医用注射液的质量。通过近二年的实际操作.列出了与去离子质量有关的主要因素,并提出一些相应见解。  相似文献   
62.
实验室制得的碱式氯化铝,用~(27)Al NMR进行分析,发现在众多聚合体中存在[AlO_4Al_(12)(OH)_(24)(H_2O)_(12)]~(7+)离子,其化学位移相对于六水合铝离子[Al(H_2O)_6]~(3+)的零位移为δ=63ppm,试铁灵定时比色法对其存在进行了验证。研究了反应条件如酸浓度、铝酸当量比和陈化时间对产物组成及质量的影响,得出最佳条件为盐酸浓度16%,铝酸当量比为1:0.5,陈化时间为50h左右。  相似文献   
63.
The effect of a systemic (IP) treatment with 1.0, 3.0 and 9.0 mg/kg U-50,488H (U50), a highly selective kappa-agonist, on spontaneous, nocturnal ingestive behavior of the rat was studied using a microcomputer controlled data acquisition system. The latency to initiate drinking was increased and drinking behavior was suppressed in the first hour after injection in a dose-dependent manner. The consummatory indices of drinking were not affected. After this period of adipsia, a phase of polydipsia, that was probably due to the diuretic effect of U50, was evident. The prophagic effect of U50 was evident only at the dose of 3 mg/kg and was accompanied by an increased duration of feeding episodes but not by a reduced latency to feed. These results suggest that kappa-receptors play a pivotal role in modulating spontaneous drinking in the normally hydrated rat and that this control is mainly exerted on the motivational aspect of drinking.  相似文献   
64.
Body composition measured with isotopic dilution was compared with anthropometric measurements. The study was carried out in 47 subjects from both sexes, 65 to 92 years old. Total body water (TBW), anthropometric measurements, and dynamometry were assessed. TBW was significatively higher in men than women and decreased with age. Dynamometry and fatfree mass were well correlated (r=0.73 in males and r=0.58 in females) and significantly different between sexes. A negative correlation was found for dynamometry with age, being significant for women. Linear regression equations to predict TBW from anthropometric measurements in males and females were obtained: Males: TBW(I)=19.349+0.617 weight(kg) — 0.931 mid-arm circumference(cm)+0.122 dynamometry (kg) Females: TBW(l)=−5.531+0.343 weight(kg)-0.213 triceps skinfold (mm)+ 0.148 dynamometry(kg) + 3.424 wrist diameter (cm). This simple model is proposed for use in epidemiological and field studies where other more sophisticated methods can not be applied.  相似文献   
65.
The prevention of the spread of disease by drinking water relies on a tripartate arrangement among the supplier, the regulator and their medical advisers. This paper describes the role of Public Health Medicine in Scotland in preventing a ‘significant risk to health’ from potable water. The legislative framework is highlighted. The rationale of water monitoring is examined and the role of Consultant in Public Health Medicine. The concept of Significant Medical Risk Values is introduced and their derivation, uses, and levels presented.  相似文献   
66.
The HACCP (hazard analysis critical control point) concept is now widely applied in the food industry and provides a structured and critical approach to the identification and control of hazards that may affect food safety. It has shifted the emphasis for control from retrospective end-product testing to the effective control of raw materials and key processing operations.
This paper discusses how the HACCP approach can be applied to enteral feeding. This involves each unit assembling a multidisciplinary team of personnel involved in enteral feeding. This team will then carry out a detailed analysis of the process from selection of ingredients and feeding systems through to consumption of the feed by the patient by constructing a flow chart that relates specifically to each unit. They can then identify and assess the hazards associated with the handling of the product at each stage in the process. This will enable them to identify the points where control over an identified hazard can be achieved (critical control points, CCP) such as quality of ingredients, design of administration systems, preparation and distribution of the feeds and the procedures involved in the assembly and manipulation of the systems. Control and monitoring procedures can then be specified and implemented at relevant stages in the process. The major strengths of the HACCP procedure are that it entails a team effort from key personnel involved in the full range of activities associated with the product and each detailed analysis is specific to each unit's practices and resources and can be continually reviewed and modified in response to changing circumstances.  相似文献   
67.
江门市乡镇集中式供水卫生现状分析   总被引:1,自引:0,他引:1  
为加强乡镇集中式供水卫生管理,进一步普及与提高农村的改水工作,我们按统一的调查方案,于1994 ̄1995年在全国范围内开展乡镇自来水厂调查登记和水质监测工作。据统计全市建成投产乡镇水厂68座,普及率77.3%,受益人口149.09万,占农村总人口62.5%,调查结果显示,水源总污染率为8.82%,在监测项目中主查细菌学指标合格率不高,丰、枯水期水源水平均合格率分别为40.0%和88.9%,而出厂水  相似文献   
68.
Twenty-four mongrel dogs were anaesthetized and ventilated mechanically in the supine position. Extravascular lung water (EVLW) and central blood volume (CBV) were measured with a double indicator (dye/cold) dilution technique. Both indicators were detected intravascularly in the aortic root with a fibreoptic thermistor catheter. Seven dogs ventilated with a positive end-expiratory pressure (PEEP) of 1.0 kPa (10 cmH2O) for a short period of time (less than 20 min) displayed no significant change in EVLW as measured with the indicator dilution technique (= EVLWi), while reductions were seen in both CBV (15%, P less than 0.01) and cardiac output (CO-thermodilution technique) (10%, P less than 0.05). Another seven dogs ventilated with a PEEP of 1.0 kPa for 8 h showed a gradual increase in EVLWi. After 8 h, a mean increase of 34% (P less than 0.01) was recorded, and the increase was also verified by post-mortem gravimetric determination of EVLW (= EVLWg), displaying an increase of 61% (P less than 0.01). In five dogs ventilated with zero end-expiratory pressure (ZEEP) for 8 h, no changes in EVLWi, CO, and CBV were observed, and EVLWg was mean 4.39 g/kg body weight (BW). Five additional dogs were sacrificed after 15 min of anaesthesia without catheterization and EVLWg was found to be 4.24 g/kg BW. It is concluded that EVLWi does not change measurably during ZEEP or short periods of PEEP. However, long periods (8 h) of PEEP result in elevated EVLWi values. Gravimetry supports these conclusions.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
69.
【目的】探索妊娠期精神压力对大鼠子代早期空间学习、记忆能力的影响。【方法】实验采取产前束缚压力,建立妊娠期大鼠精神压力暴露模型。然后对子代进行Morris水迷宫测试,分析妊娠期压力对子代早期学习和记忆的影响及性别间的差异,同时检测实验前、后子鼠的血清肾上腺酮的变化。【结果】①在隐蔽平台试验中,对照组的平均潜伏期较实验组短,但差异无显著性(F=0.599,P>0.05)。②在保持力试验中,对照组在原平台所在象限逗留的时间大于实验组,差异有显著性(F=4.588,P<0.05)。③子代血清肾上腺酮的测定结果表明:水迷宫测试前,实验组和对照组相比,差异无显著性(F=0.169,P>0.05);实验后,实验组血清肾上腺酮比对照组高,差异具有显著性(F=6.098,P<0.05)。【结论】①妊娠压力可导致子代学习,记忆能力的改变;②妊娠压力造成子代在应激情况下血清肾上腺酮的过度分泌。③妊娠压力对子代的影响没有明显性别差异。  相似文献   
70.
HQJ-500多功能净水装置装舰试用评价   总被引:1,自引:1,他引:0  
目的:改善舰船官兵的饮用水水质,提高舰员的生活质量。方法:将研制的HQJ-500多功能净水装置装舰试用,征求试用意见并进行水质分析。结果:经实船试用证实,该多功能净水器能经受住各种海况下颠簸,摇晃的考验。运行正常。处理后的水质有明显改善。结论:该装置净化,消毒效果肯定,适合舰船使用,可推广应用。  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