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   5218篇
  免费   440篇
  国内免费   131篇
耳鼻咽喉   24篇
儿科学   97篇
妇产科学   63篇
基础医学   1088篇
口腔科学   225篇
临床医学   281篇
内科学   761篇
皮肤病学   124篇
神经病学   353篇
特种医学   77篇
外科学   511篇
综合类   528篇
现状与发展   2篇
预防医学   207篇
眼科学   79篇
药学   769篇
中国医学   157篇
肿瘤学   443篇
  2023年   69篇
  2022年   91篇
  2021年   184篇
  2020年   123篇
  2019年   200篇
  2018年   165篇
  2017年   139篇
  2016年   149篇
  2015年   162篇
  2014年   271篇
  2013年   327篇
  2012年   224篇
  2011年   317篇
  2010年   255篇
  2009年   270篇
  2008年   255篇
  2007年   277篇
  2006年   269篇
  2005年   225篇
  2004年   205篇
  2003年   206篇
  2002年   160篇
  2001年   119篇
  2000年   90篇
  1999年   74篇
  1998年   59篇
  1997年   43篇
  1996年   46篇
  1995年   65篇
  1994年   49篇
  1993年   51篇
  1992年   31篇
  1991年   41篇
  1990年   30篇
  1989年   24篇
  1988年   28篇
  1987年   27篇
  1986年   29篇
  1985年   51篇
  1984年   55篇
  1983年   62篇
  1982年   38篇
  1981年   34篇
  1980年   42篇
  1979年   25篇
  1978年   24篇
  1977年   18篇
  1976年   21篇
  1975年   15篇
  1973年   14篇
排序方式: 共有5789条查询结果,搜索用时 15 毫秒
1.
The invasive measurement of physiological pressures is a common requirement in anaesthesia and intensive care medicine. From arterial blood pressure to intracranial pressure, these calculated variables give a swift graphical and numerical representation of a patient's current physiological status. This allows us to respond rapidly to conditions outside our preferred parameters and to carefully titrate treatment to target effects. These systems are, however, not infallible. An understanding of the principles of their function will promote appropriate use and an ability to recognize and react to sources of error. This article aims to furnish the reader with this level of understanding in order to inform their academic and clinical practice.  相似文献   
2.
Abstract

Objective

Two similarly designed studies compared user experiences with a second-generation extra-thin-wall, 5-bevel 32?G?×?4?mm pen needle (PN) with redesigned hub versus four thinner commercially available PNs.  相似文献   
3.
目的 探讨microRNA-613调控细胞周期蛋白依赖性激酶14(CDK14)通路来抑制老年胶质瘤患者瘤细胞增殖和侵袭的机制。方法 购自上海北诺生物科技有限公司的人脑胶质瘤细胞株U251共24株,分为shNC组、shmicroRNA-613组、Vector组、microRNA-613组,每组各6株; Western Blotting法和qRT-PCR法检测敲减microRNA-613和过表达microRNA-613后的人脑胶质瘤细胞株U251中CDK14蛋白表达水平,CCK-8细胞增殖实验、Transwell小室实验验证敲除microRNA-613和过表达microRNA-613后U251细胞的增殖、侵袭能力。结果 人胶质瘤细胞株U251敲减microRNA-613后CDK14蛋白表达增加(P<0.05); 人胶质瘤细胞株U251过表达microRNA-613后CDK14蛋白表达减少(P<0.05); 转染第24、36、48 h microRNA-613组U251细胞增殖率P<0.05); microRNA-613组U251细胞侵袭能力>Vector组,shNC组>shmicroRNA-613组(P<0.05)。结论 microRNA-613可通过调控CDK14信号转导通路来抑制人脑胶质瘤细胞U251增殖、转移。  相似文献   
4.
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6‐dihydroxy‐2‐mercaptopyrimidine 3 . Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6‐dimethoxy‐2‐methylsulphonylpyrimidine 5 . Compound 5 on condensation with 2‐mercapto‐6‐chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac‐sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]‐thiourea in lieu of thiourea, 14C labelled product 6 , was synthesized with an overall radiochemical yield > 30% (with respect to [14C]‐thiourea) for further evaluations of environmental fate of 6 , in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
5.
目的阐明针刺捻转补法与泻法的操作是否存在效应上的差异,并探讨其效应差异是否为补泻效应的差异.方法应用红外线热像技术,采用不同的捻转补泻手法针刺健康人合谷穴后,观察其在即刻,10、20、30min,对局部皮肤温度的影响.结果不同捻转补法与泻法的操作存在着不同程度的效应差异,其中补法可以使皮温升高,泻法可以使皮温降低,以石氏捻转补泻针法较为明显.结论1)补泻手法,补法和泻法的操作可产生不同的效应.2)不同捻转补泻手法对皮肤温度产生的升降效应为补泻效应,其中以石氏捻转补泻手法最为明显.3)证明补泻手法实施的必要性.  相似文献   
6.
p14ARF基因和核转录因子E2F-1在细胞周期调控,细胞凋亡和肿瘤发生中具有重要作用。近年来,有研究表明p14ARF在肺癌中的表达率低于正常组织,E2F-1的表达率高于正常组织。本文将就p14ARF、E2F-1与肺癌的关系进行综述。  相似文献   
7.
稳定性核素测定大鼠小肠蛋白质合成   总被引:2,自引:1,他引:1  
目的:建立稳定性核素([L-^15N]亮氨酸)测定大鼠小肠蛋白质合成率的方法。方法:分别测定静脉注射相同剂量[L-^15N]亮氨酸不同时相的大鼠小肠^15N丰度及不同剂量[L-^15N]亮氨酸同一时相的大鼠小肠^15N丰度。结果:大鼠小肠游离氨基酸池中^15N核素丰度在注射后0.5h内呈线性上升并达高峰,维持4h后缓慢下降,小肠蛋白质中的^15N丰度0.5h至12h基本维持不变;随着注射剂量的增加,大鼠小肠蛋白质分数合成率(FSR)亦增加,当[L-^15N]亮氨酸剂量在1.0mmol/kg以上,FSR并不随施加[L15N]亮氨酸剂量的加大而增加。结论:在进行大鼠小肠蛋白质合成率测定时,一次性静脉注射的测量最佳时限为0.5h,剂量为1.0mmol/kg。  相似文献   
8.
The endotoxin receptor soluble CD14 (sCD14) has been implicated in the 'hygiene hypothesis' suggesting reduced allergic sensitization with bacterial stimulation. However, the relationship between early life sCD14 and allergic diseases is conflicting. We aimed to investigate whether possible risk factors for allergic diseases were associated with sCD14 levels at 2 yr of age. In the nested case-control study of the birth cohort studies 'Environment and Childhood Asthma study in Oslo' 411 children selected with recurrent bronchial obstruction (rBO) (n=241) and no bronchial obstruction (n=170) by 2 yr were investigated with skin prick test and structured parental interview at age 2 yr. Exposure to tobacco smoke, pets and infections was recorded semi-annually by questionnaires (0-2 yr). The sCD14 was analysed from frozen, stored serum by ELISA technique. Regression analyses were performed in all subjects with complete data (n=406, 180 girls), and in girls and in boys separately. Mean sCD14 (ng/ml) was significantly higher among girls 2035 (1973-2096) vs. 1947 (1890-2004) (boys). The sCD14 was significantly reduced among girls exposed to antenatal maternal smoking and with parental asthma, after adjusting for age, parental rhino-conjunctivitis, pet keeping and childhood infections. Recurrent otitis media (OM) increased and common colds significantly decreased sCD14 levels in girls. Boys with atopic dermatitis and rBO had reduced sCD14. Pet exposure was not significantly associated with sCD14. We report novel gender-related effects of sCD14 in early life and suggest that gender, tobacco smoke exposure, age and middle ear disease in particular should be accounted for when assessing the role of sCD14 in childhood allergic diseases.  相似文献   
9.
ABSTRACT. During the late winter of 1983, 16 newborns with vague symptoms of failure to thrive, reluctance to feed and a slight rise in body temperature, were found to have meningitis caused by Coxsackievirus A-14. The cerebrospinal fluid showed pleocytosis with polymorphonuclear cells in excess but was otherwise normal. The clinical course was uneventful in all infants, but two of them demonstrated clinical signs of incipient cerebral oedema during the acute phase of the illness. An electroencephalogram (EEG) during the initial course of the disease and at nine months of age was normal in all. During a follow-up period of 21/2 years they all developed normally and no sequelae were noted. The presentation also demonstrates the usefulness of Vero cells for the propagation of the responsible virus.  相似文献   
10.
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