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   861篇
  免费   47篇
  国内免费   1篇
耳鼻咽喉   11篇
儿科学   40篇
妇产科学   5篇
基础医学   125篇
口腔科学   27篇
临床医学   61篇
内科学   156篇
皮肤病学   8篇
神经病学   58篇
特种医学   41篇
外科学   92篇
综合类   20篇
预防医学   75篇
眼科学   7篇
药学   97篇
中国医学   5篇
肿瘤学   81篇
  2022年   13篇
  2021年   17篇
  2020年   9篇
  2019年   10篇
  2018年   8篇
  2017年   14篇
  2016年   22篇
  2015年   28篇
  2014年   26篇
  2013年   40篇
  2012年   72篇
  2011年   51篇
  2010年   32篇
  2009年   30篇
  2008年   33篇
  2007年   34篇
  2006年   48篇
  2005年   25篇
  2004年   20篇
  2003年   21篇
  2002年   22篇
  2001年   14篇
  2000年   17篇
  1999年   5篇
  1998年   8篇
  1997年   9篇
  1996年   14篇
  1995年   6篇
  1994年   8篇
  1993年   12篇
  1992年   18篇
  1991年   11篇
  1990年   19篇
  1989年   26篇
  1988年   23篇
  1987年   19篇
  1986年   14篇
  1985年   10篇
  1984年   7篇
  1981年   7篇
  1980年   7篇
  1979年   7篇
  1978年   6篇
  1977年   7篇
  1976年   6篇
  1974年   6篇
  1973年   6篇
  1972年   5篇
  1969年   4篇
  1968年   4篇
排序方式: 共有909条查询结果,搜索用时 15 毫秒
1.
Frequency of sickle cell in Scheduled Caste and Scheduled Tribe populations was found to be 1.5 and 14.9% respectively, whereas G-6-PD deficiency was 5.9 and 4.2% respectively. Blood group B was dominant in both the communities. A significantly lower frequency of P. falciparum malaria was observed among sicklers.  相似文献   
2.
3.
Thirty-eight patients with convexity lesions were studied prospectively with the two-dimensional time-of-flight (2D-TOF) magnetic resonance angiography (MRA) method. Of these 21 cases had additional surface anatomy scanning (SAS) and 7 cases had three-dimensional phase contrast (3D-PC) MRA. The findings were compared during surgery, and the predictability of 2D-TOF evaluated. 2D-TOF was obtained with 2 mm slice thickness after the administration of contrast media for routine magnetic resonance imaging (MRI). Cortical veins were visualized with a good resolution with a scan time of only 5 minutes. The tumor was also visible in the background, due to enhancement, and thus the tumor-vessels relation was shown. Slow-flow vessels were also adequately seen. SAS was done at the same sitting with fast spin echo (FSE) with a scan time of 3 minutes. Once both images were incorporated, information on gyri and their relation to the lesions and vasculature could be obtained from a single image. We found 2D-TOF alone, or at times in combination with SAS, useful for planning of operation for convexity lesions.  相似文献   
4.
Circannual variation in lymphocyte subsets, revisited   总被引:2,自引:0,他引:2  
BACKGROUND: Circadian and circannual variations in lymphocyte subsets, especially CD8+ T-lymphocytes, have been reported. This study focuses on CD4+ T-lymphocyte seasonal variation over a 6-year 8-month period. STUDY DESIGN AND METHODS: Lymphocyte subsets were quantitated monthly for four healthy individuals from 1986 through 1992 as part of a flow cytometry quality-control program. RESULTS: In general, there were no significant seasonal changes in the total number of white cells or in total lymphocyte counts. The absolute numbers of CD4+ T-lymphocytes were lowest in summer when the CD8+ T-lymphocytes were highest. Mean CD4+ T-lymphocyte counts were 846, 967, 618, and 695 per microL for Subjects 1 through 4, respectively, in winter and 432, 670, 355, and 766 per microL, respectively, in summer. Two healthy subjects had CD4+ T-lymphocyte counts lower than 300 per microL on one or more occasions during the study period. In three of the four subjects, the percentage of B-lymphocytes in winter was almost double that in summer. In one of the four subjects, no circannual rhythm was observed in these lymphocyte subpopulations. CONCLUSION: The seasonal variation in CD4+ T- lymphocyte counts demonstrated in three healthy individuals over almost 7 years is again of interest in light of renewed consideration of using surrogate tests, such as CD4+ T-lymphocyte counts, to screen for AIDS- like diseases that may be in the blood supply.  相似文献   
5.
The family history in family practice: a questionnaire study   总被引:9,自引:7,他引:2  
Summerton  N; Garrood  PV 《Family practice》1997,14(4):285-288
OBJECTIVES: Our aims were to investigate family medical history taking in general practice, and to evaluate the value attached to the family medical history as an aid to decision making in general practice. METHOD: A postal questionnaire survey was conducted among all 291 GPs working within the Calderdale and Kirklees Health Authority area. Each questionnaire was followed by a reminder. The main outcome measures were answers to questions on routine and opportunistic family history taking and a question about transmitting knowledge about genetic risk to other members of the family. Questions were also posed about the value attached to the family medical history as an aid to decision making. RESULTS: A total of 193 GPs returned the questionnaire (response rate 66.3%). On registration, 94.3% of GPs indicated that enquiries were made about a family history of coronary heart disease. Breast and colorectal cancer were specifically asked about by 48.4% and 30.7% of GPs, respectively. One-fifth of respondents indicated that they asked a general question about family medical history. A little over one-quarter of respondents indicated that they made opportunistic enquiries about the family history or suggested that the patient should inform other members of the family about possible risks. In the scenarios highlighted in this study, the majority of respondents felt that the family medical history had value as an aid to decision making. This was particularly the case for checking a patient's cholesterol (92.1%) and for initiating referrals in younger patients with possible cancer-related symptoms (three-quarters of respondents). CONCLUSION: GPs value the family medical history as an aid to decision making. Unfortunately, apart from enquiries about coronary heart disease, routine or opportunistic family history taking is not occurring in practice. Mechanisms need to be sought to extract information from the family medical history so that it can be more effectively used by GPs.   相似文献   
6.
Comparative DNA sequence studies between humans and nonhuman primates will be important for understanding the genetic basis of the phenotypic differences between these species. Here we compare approximately 27 Mb of human chromosome 21 with chimpanzee DNA sequences identifying 57 genomic rearrangements (deletions and insertions ranging in size from 0.2 to 8.0 kb) between the two species. These rearrangements are distributed along the entire length of chromosome 21, with approximately 35% found in genomic intervals encoding genes (genic intervals), and have occurred in the genomes of both humans and chimpanzees. Comparison of approximately 9 Mb of human chromosome 21 with orangutan, rhesus macaque, and woolly monkey DNA sequences identified a combined total of 114 genomic rearrangements between humans and nonhuman primates. Analysis of these rearrangements revealed that they are randomly distributed with respect to genic and nongenic intervals and identified one deletion that has likely resulted in the inactivation of a gene (beta1,3-galactosyltransferase) in the woolly monkey. Our data show that genomic rearrangements have occurred frequently during primate genome evolution and significantly contribute to the DNA differences between these species. These DNA rearrangements are commonly found in genic intervals, and thus provide natural starting points for focused investigations of qualitative and quantitative gene expression differences between humans and other primates.  相似文献   
7.
Summary The Bezold-Jarisch reflex characterized by hypotension and bradycardia was elicited in anaesthetized artificially respired dogs (pretreated with a beta-adrenoceptor antagonist) using capsaicin 10 g/kg (i.v.). Intracisternal administration of the highly selective clonidine-like alpha2 adrenoceptor agonists B-HT 920 (10 g/kg) or B-HT 933 (30 g/kg) significantly facilitated this reflex bradycardia. The involvement of central alpha2-adrenoceptors is suggested as intracisternal administration of the alpha2 adrenoceptor blocking drugs yohimbine (50 g/kg) and piperoxan (50 g/kg) antagonized this facilitation. B-HT 920 also facilitated the vagally mediated baroreceptor reflex to the hypertensive effect of intravenous noradrenaline (3 g/kg). Although the Bezold-Jarisch reflex and the baroreceptor reflex have different afferent pathways, both reflexes may either converge into a common pathway or have separate neuronal chains within the medulla; however, this study indicates that both have a similar central modulatory system stimulated by alpha2 adrenoceptors.  相似文献   
8.
Subacute (90 days) oral toxicity studies of Kombucha tea   总被引:4,自引:0,他引:4  
Kombucha tes(KT) is a popular health beverage and is used as an alternative therapy,KT is prepared by placing the kombucha culture in solution of tea and sugar and allowing to ferment,The inoculum is a fungus consisting of symbiotic colony of yeast and bacteria.KT is consumed in several coutries and is believed to have prophylactic and therapeutic benefits in a wide variety of ailments,viz.,intestinal disorders,arthritis,ageing and stiumulation of immunological system.Though KT is used in several parts of the world its eneficial effects and adverse effects have not been scientifically evaluated.Since there are no animal toxicological data on KT,subacute oral toxicity study was carried out.Five goups of rats were maintained:(a) control group given tap water orally,(b) KT given 2ml/kg orally,(c)plain tea(PT) given 2ml/kg orally,(d)KT given in drinking water,1%(v/v)and (e)PT given indrinking water,1%(v/v).The rats were given this treatment daily for a period of 90 days,Weekly records of weight,feed intake,water intake and general behaviour were monitored.There was no significant difference in the growth of the animals as evidenced by the progrssive body weight change.The organ to body weight ration and histologuical evaluation did not show any toxic signs.The haematological and biochemical variables,were within the clinical limits.The study indicates that rats fed KT for 90 day showed no toxic effects.  相似文献   
9.
The effect of Prunus amygdalus, which is rich in unsaturated fat, fibre diet and low cholesterol was studied in 36 normolipidemic male albino rabbits for 60 days. Three different doses i.e. whole seeds defatted and oil showed a decrease in serum total cholesterol, triglyceride, LDL cholesterol, VLDL cholesterol and an increase in phospholipid, faecal sterol and HDL cholesterol. The maximum effects where shown by whole seeds followed by oil and defatted.  相似文献   
10.
This study was undertaken to examine the efficacy of lidocaine aerosol pretreatment in attenuating hemodynamic (HD) responses secondary to laryngoscopy and tracheal intubation in patients undergoing surgery for intracranial space occupying lesions (ICSOL). A semiclosed breathing system was improvised to generate aerosol of consistent density. Five percent lidocaine was nebulized in two different dosages (0.2 and 0.1 ml/kg in groups A and B, respectively); group C (control) received aerosol of normal saline. The average aerosol-treatment time was 24, 12, and 16 min in groups A, B, and C, respectively. Changes in heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and rate pressure product (RPP) were analyzed by analysis of variance (ANOVA). In group A, tracheal intubation did not cause significant HD changes. In group B, a significant increase was observed in each HD parameter which, when compared with control, was less severe. Lidocaine toxicity, regurgitation, nausea, vomiting, or aspiration did not occur in any patient. Patients accepted the procedure well. This study found efficacy of the technique to be related to duration of aerosol treatment.  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