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   1335篇
  免费   100篇
  国内免费   20篇
耳鼻咽喉   8篇
儿科学   5篇
妇产科学   8篇
基础医学   184篇
口腔科学   10篇
临床医学   182篇
内科学   106篇
皮肤病学   3篇
神经病学   323篇
特种医学   20篇
外科学   66篇
综合类   77篇
预防医学   250篇
眼科学   16篇
药学   139篇
中国医学   49篇
肿瘤学   9篇
  2024年   4篇
  2023年   8篇
  2022年   25篇
  2021年   42篇
  2020年   37篇
  2019年   37篇
  2018年   43篇
  2017年   38篇
  2016年   40篇
  2015年   56篇
  2014年   73篇
  2013年   106篇
  2012年   65篇
  2011年   90篇
  2010年   82篇
  2009年   73篇
  2008年   45篇
  2007年   57篇
  2006年   66篇
  2005年   38篇
  2004年   41篇
  2003年   48篇
  2002年   41篇
  2001年   23篇
  2000年   27篇
  1999年   19篇
  1998年   22篇
  1997年   23篇
  1996年   21篇
  1995年   14篇
  1994年   10篇
  1993年   6篇
  1992年   7篇
  1991年   9篇
  1990年   5篇
  1989年   8篇
  1988年   8篇
  1987年   2篇
  1986年   8篇
  1985年   6篇
  1984年   16篇
  1983年   13篇
  1982年   8篇
  1981年   15篇
  1980年   10篇
  1979年   3篇
  1978年   4篇
  1977年   3篇
  1975年   3篇
  1973年   5篇
排序方式: 共有1455条查询结果,搜索用时 15 毫秒
11.
This study examined the possibility that amphetamine-induced stereotypy and facilitation of memory consolidation are both mediated by amphetamine's stimulation of dopaminergic activity in the caudate nucleus. In the first experiment, rats were given pairings of a tone and a shock followed by SC amphetamine (2 mg/kg). The amount of stereotypy and increased locomotor activity produced by the injection were measured immediately. Retention of the tone-shock association was evaluated 48 h later by observing the ability of the tone to suppress drinking. The degree of retention was significantly correlated with the amount of stereotypy but not with the amount of locomotion previously measured. In the second experiment, amphetamine was microinjected into the caudate nucleus (10 g/l) and its ability to produce the same three behavioral effects was examined. These injections produced increased stereotypy and improved retention, but no increase in locomotion. The correlation of memory facilitation with stereotypy and the fact that both were produced by intracaudate amphetamine suggest that they may be mediated by the same neuropharmacological substrate, namely amphetamine-induced release of dopamine in the caudate.  相似文献   
12.
Summary The interaction between rauwolscine and angiotensin II was investigated in the isolated mesenteric artery of the rabbit. Rauwolscine, known as an antagonist at 2-adrenoceptors, did not induce contraction itself but interacted with angiotensin to produce a facilitated response of the vascular tissue. In the presence of rauwolscine, the contractile response of the tissue to angiotensin was markedly enhanced. The degree of facilitation appeared to be dependent on the rauwolscine concentration used rather than that of angiotensin. Moreover, rauwolscine induced a concentration-dependent increase in tension (pD2=6.8) in the presence of even subcontractile concentrations of angiotensin (10–10 mol/l). This effect was not attributable to an indirect action involving presynaptic catecholamines, as revealed by the use of tissue strips from animals pretreated with reserpine or after chemical sympathectomy. Furthermore, an interaction via the prostaglandin system was excluded by negative results obtained with indomethacin. The agonistic effect of rauwolscine was significantly attenuated by phentolamine (1/2) but not by prazosin (1) or phenoxybenzamine when applied for only a short time. The 2-antagonist BDF 6143 behaved like rauwolscine whereas the 1-antagonist corynanthine, a stereoisomer of rauwolscine, did not. The results indicate that the rauwolscine effect is mediated by a receptor with 2-characteristics. In general, angiotensin appears to interfere with some process which determines the expression of a drug's intrinsic effect.This study was supported by a grant of the Deutsche Forschungsgemeinschaft  相似文献   
13.
饮食服务业从业人员乙型肝炎病毒感染动态研究   总被引:1,自引:0,他引:1  
目的为了解泰安市饮食服务业从业人员乙型肝炎病毒感染状况。方法应用ELISA方法在1995~1999年对53434名饮食服务业从业人员进行了血清HBsAg、抗-HBc、HBeAg和抗-HBe检测。结果1995~1999年饮食服务业从业人员血清HBsAg、抗-HBc、HBeAg和抗-HBe总阳性率呈逐年下降趋势,依次为4.41%、3.88%、3.46%、2.86%和2.50%,其差异有显著意义(χ  相似文献   
14.
21纪我国医药行业的创新与发展   总被引:3,自引:0,他引:3  
在分析我国医药行业发展现状及存在问题的基础上,研究了加入WTO后医药行业所面临的机遇与挑战,以及当前医药企业技术创新存在的不足,提出了21世纪我国医药行业创新与发展的对策和建议。  相似文献   
15.
The use of PHOTOFRIN for photodynamic therapy of human gliomas has been studied by i.v. administration and laser photosensitization. Defining the uptake of PHOTOFRIN in the patient's tumor in comparison with the surrounding normal brain tissue is highly desirable for patient selection and study ofin vivo kinetics. We utilized a non-invasive approach to the detection of PHOTOFRIN uptake in brain tumors with111In-oxine radiolabeled PHOTOFRIN and external imaging and quantitation using a gamma camera. Biodistribution of111In-labeled PHOTOFRIN in 13 organs was determined in four dogs and 15 mice with gliomas.99mTc-DTPA was used as a control for nonspecific uptake. The greatest concentration of111In-PHOTOFRIN in the brain tumor occurred at 24 hours post i.v. administration. The brain tumor PHOTOFRIN uptake was seven times greater than that of normal brain. The decreased blood background at 72 hours made this the optimum time for imaging. Specific tumor tissue uptake of111In-PHOTOFRIN occurred, well beyond that resulting from blood-brain-barrier (BBB) breakdown.  相似文献   
16.
We have described the epidemiological analysis of one aspect of the King's College Hospital computerised data base; namely initial intraocular pressure as an indicator of visual field loss. The methods involved the use of the four-fold table to determine sensitivity and specificity at different pressure levels. From these results (1) the changes in the pre and post test probability of field loss are calculated and (2) a sensitivity/specificity trade off curve or decision curve is constructed. In this way the optimal cut-off level or operating point for a population of specific type and composition can be determined. The factors concerned in decision making are always complex but such an approach allows a rational and quantifiable alternative to reliance on clinical impression and intuition. The results have significance in relation to decisions on the management of patients and on population screening programmes for glaucoma.  相似文献   
17.
Low doses of oxytocin facilitate social recognition in rats   总被引:7,自引:0,他引:7  
Social recognition of juveniles by adult male residents has been shown to be modulated by neurohypophyseal hormones. The decrease of social investigation behavior during a second encounter with the same juvenile serves as index for social recognition. In the present study it was found that low doses (0.09–6.0 ng · kg–1) of oxytocin (OXT) given subcutaneously dose dependently facilitated social recognition. The effect of OXT appeared specific, since no change in social investigation was found when a novel juvenile was tested during the second encounter. No disturbances of social recognition by the low doses of OXT could be detected, in contrast to higher doses of this hormone. Other neurohypophyseal hormones, vasopressin and vasotocin, did not facilitate social recognition when tested in the same range of low doses.  相似文献   
18.
我国医药行业现状与发展趋势   总被引:26,自引:3,他引:26  
目的 :为了解我国医药行业现状和发展趋势提供参考。方法 :概述我国医药行业的基本情况和存在的问题 ,并对我国医药行业未来发展趋势进行分析、讨论。结果与结论 :我国医药企业必须重视自身存在的问题以及加入世界贸易组织带来的机遇和挑战 ,结合实际 ,采取相应对策 ,不断加强、提高自身的竞争能力 ,共同维护我国医药行业的健康、持续、稳定发展。  相似文献   
19.
Thyroid hormones are critical for the development and maturation of the central nervous system. Insufficiency of thyroid hormones during development impairs performance on tasks of learning and memory that rely upon the hippocampus and impairs synaptic function in young hypothyroid animals. The present study was designed to determine if perturbations in synaptic function persist in adult euthyroid animals exposed developmentally to insufficient levels of hormone. Pre- and postnatal thyroid hormone insufficiency was induced by administration of 3 or 10 ppm propylthiouracil (PTU) to pregnant and lactating dams via the drinking water from gestation day (GD) 6 until postnatal day (PN) 30. This regimen produced a graded level of hormonal insufficiency in the dam and the offspring. Population spike and population excitatory postsynaptic potentials (EPSP) were recorded at the pyramidal cell layer and the stratum radiatum, respectively, in area CA1 of hippocampal slices from adult male offspring. PTU exposure increased baseline synaptic transmission, reduced paired-pulse facilitation, and increased the magnitude of the population spike long-term potentiation (LTP). Phosphorylation of the extracellular signal-regulated kinases (ERK1 and ERK2) was increased as a function of LTP stimulation in slices from PTU-exposed adult animals. On the other hand, no differences in the basal levels of synaptic proteins implicated in synaptic plasticity (total ERK, synapsin, growth-associated protein-43, and neurogranin) were detected. These results reinforce previous findings of persistent changes in synaptic function and, importantly extend these observations to moderate levels of thyroid hormone insufficiency that do not induce significant toxicity to the dams or the offspring. Such alterations in hippocampal synaptic function may contribute to persistent behavioral deficits associated with developmental hypothyroidism.  相似文献   
20.
应用HACCP原则在餐饮业中的作用   总被引:4,自引:0,他引:4  
杨波  高峰  秦筱筠  孟强 《现代预防医学》2004,31(4):570-571,574
目的:在餐饮业中应用HACCP管理系统,保证食品质量安全,预防食物中毒发生。方法:分析1995∽1999年日照市5年内12家单位食物中毒发生的特点,找出存在的危害环节,制订控制措施,成立以经理、厨师、采购员、服务员领班为成员的领导小组,通过监督部门培训指导,负责实施HACCP计划。结果:自2000年,在实施HACCP管理单位中,未再发生食物中毒。结论:在餐饮业应用HACCP管理是有效的。将HACCP原则作为执行标准是必要的。  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