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   222292篇
  免费   14707篇
  国内免费   2085篇
耳鼻咽喉   2692篇
儿科学   6711篇
妇产科学   4650篇
基础医学   28750篇
口腔科学   8584篇
临床医学   18535篇
内科学   47931篇
皮肤病学   5373篇
神经病学   17232篇
特种医学   6744篇
外国民族医学   32篇
外科学   26829篇
综合类   7533篇
现状与发展   3篇
一般理论   69篇
预防医学   22208篇
眼科学   4276篇
药学   15206篇
  53篇
中国医学   2963篇
肿瘤学   12710篇
  2023年   1474篇
  2022年   3066篇
  2021年   6127篇
  2020年   4228篇
  2019年   5105篇
  2018年   6712篇
  2017年   5313篇
  2016年   4797篇
  2015年   6035篇
  2014年   8189篇
  2013年   10066篇
  2012年   15357篇
  2011年   15889篇
  2010年   8914篇
  2009年   7953篇
  2008年   11955篇
  2007年   12513篇
  2006年   11453篇
  2005年   11422篇
  2004年   10320篇
  2003年   9484篇
  2002年   7182篇
  2001年   5398篇
  2000年   5312篇
  1999年   4659篇
  1998年   1894篇
  1997年   1629篇
  1996年   1587篇
  1995年   1320篇
  1994年   1290篇
  1993年   1184篇
  1992年   2773篇
  1991年   2643篇
  1990年   2426篇
  1989年   2438篇
  1988年   2194篇
  1987年   2020篇
  1986年   1906篇
  1985年   1824篇
  1984年   1310篇
  1983年   1063篇
  1982年   644篇
  1981年   609篇
  1980年   548篇
  1979年   967篇
  1978年   633篇
  1977年   527篇
  1975年   569篇
  1974年   553篇
  1973年   557篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Thermal injury sustained during pregnancy presents special management problems for the gravid woman and her unborn child. Because of the reported high morbidity and mortality and lack of available data in South Africa, a multicentre retrospective review was undertaken by five burn centres. Thirty-three patients (average age 25,7 years) with mean 30% (range 1-80%) total body surface area burn were assessed. A review of the clinical material led to the following observations and conclusions. Pregnancy does not influence maternal outcome after thermal injury and maternal survival is usually accompanied by fetal survival in the absence of significant maternal complications. Maternal survival is less likely if the burn wound exceeds 50% total body surface area. Thermal injury does increase the risk of spontaneous abortion and premature labour, and fetal survival depends on fetal maturity. Early obstetric intervention is only indicated in the gravely ill patient where complications (hypoxia, hypotension, sepsis) jeopardize the life of a viable fetus. The mode of delivery should be determined by obstetric considerations.  相似文献   
992.
993.
We have performed restriction fragment length polymorphism (RFLP) analysis at the low density lipoprotein receptor (LDLR) locus in order to investigate the molecular genetics of familial hypercholesterolemia (FH) in Spain. Firstly, a sample of 50 unrelated patients with a clinical diagnosis of FH was screened for the presence of major rearrangements at this locus by Southern blot analysis of Bgt II digested genomic DNA. Four different mutations were detected, accounting for 8% of the mutant alleles in the Spanish FH sample. Then, we determined the relative allele frequency and estimated linkage disequilibrium between seven RFLPs of the LDLR gene in the remaining 46 FH patients and in 61 normolipidemic controls. Hindi, Avail, Pvu II, Msp I, and Nco I are the most polymorphic sites with individual PIC values higher than 0.28, whereas the Taq I and Stu I sites display low levels of polymorphism. The usefulness of the seven RFLPs to confirm a clinical diagnosis of FH was investigated in 15 FH-families, consisting of 118 individuals, in whom the presence of Familial Defective Apolipoprotein B-100 (FDB) due to the apoB3500 mutation was excluded. Independent haplotypes were constructed for 71 chromosomes: 15 FH and 56 control haplotypes. A total of 14 different haplotypes was found. In 12 families, clinical diagnosis of FH was confirmed by cosegregation analysis, which makes these RFLPs useful for studying the inheritance of the LDLR gene in 80% of Spanish families with FH. Comparison of haplotypes found in the Spanish sample with those found in Swiss and Norwegians suggests heterogeneity of haplotypes among European populations.  相似文献   
994.
A series of 206 necropsies in Western Australia (WA) have had routine counts made of asbestos bodies in samples of lung tissue using conventional light microscopy. Thirty-two cases had worked in the asbestos industry at Wittenoom, WA and (log) counts of asbestos bodies in their lung tissue correlated well with estimates of their (log) cumulative airborne exposure to crocidolite fibers (r = 0.60). There was no association between the number of asbestos bodies and time since exposure to asbestos ceased. In subjects without known exposure to asbestos, there was a weak but nonsignificant increase in number of asbestos bodies with increasing age, with 26% of cases having no asbestos bodies present. It is concluded that the relatively simple technique of light microscopy for counting of asbestos bodies in lung tissue provides a reliable indication of the level of past occupational exposure to crocidolite in subjects whose exposure has been only to crocidolite. This could be extremely useful in follow-up studies of cohorts that lack reliable measures of airborne exposure to crocidolite asbestos.  相似文献   
995.
J Curran  M de Melo  S Moyer  D Kolakofsky 《Virology》1991,184(1):108-116
The Sendai virus V protein, which is a fusion of the P and V ORFs of the P gene, was characterized with antisera to a portion of the V ORF and compared to the P protein. The only property found in common with P is that V is also highly phosphorylated, and this is so even when these proteins are expressed independently of the other viral proteins. Otherwise, V was not found in virions, was not strongly associated with viral nucleocapsids like P, and anti-V had no effect on viral RNA synthesis in vitro under conditions where anti-P was highly inhibitory. The available evidence suggests that V may play a role in RNA synthesis, but it is not an essential one like that of the P protein.  相似文献   
996.
The histopathological changes observed in the cutaneous rash of three patients who suffered the acute phase of HFV infection are described. In all three patients a perivascular and interstitial inflammatory infiltrate was present in the upper and mid-reticular dermis. In one biopsy isolated areas of epidermal necrosis were observed and in the two other biopsies a perifollicular inflammatory infiltrate was detected with perforation in one case. Furthermore, a periductal infiltrate was observed in one of these biopsies.  相似文献   
997.
Elaborating on the five-dimensional structure of illness representation, as described in the self-regulation model of Leventhal (1980), the present study is aimed at identifying the relevance of this generic structure for two chronic illnesses: chronic fatigue syndrome (CFS) and Addison's disease (AD). Factor analyses showed the importance of the five dimensions identity, time-line, control/cure, cause, and consequences to differ according to the type of disease. That is, the items representing the five dimensions merged together for CFS patients and AD patients in a different manner and thereby produced different factor solutions for the two patient groups. In CFS patients, a four-factor solution was identified with manageability, seriousness, personal responsibility, and external cause as the factors. In AD patients a four-factor solution was also identified but with seriousness, cause, chronicity, and controllability as the factors. The value of these findings for our understanding of the disease-specific nature of illness representation is discussed.  相似文献   
998.
In order to determine which factors predict the outcome of short term antithyroid drug treatment we studied 42 patients with diffuse goitre in whom 43 instances of thyrotoxicosis were treated. Treatment duration ranged from 24 to 61 wk (median 30 wk). All patients received high-dose carbimazole and thyroid hormone substitution. Patients in remission were followed for 39 to 134 wk (median 73 wk). The relapse rate at 1 yr and at 2 yr after cessation of antithyroid drug treatment was 51%. Of the parameters studied presence or absence of eye signs and initial serum levels of thyroxine, triiodothyronine and immunoglobulin-G in the relapse group and in the remission group showed significant differences in univariate analysis. No significant differences were found for age, sex, family history of thyroid disease, thyroid gland volume or TSH-receptor stimulating autoantibodies. Linear discriminant analysis shows that of the four remaining factors thyroxine is not important in separating both groups. Cox analysis yields only initial serum triiodothyronine and eye signs as significant prognostic factors. With these two factors 18 out of 23 predictions of remission and 16 out of 18 predictions of relapse in the 41 patients with known initial serum triiodothyronine concentrations are correct. Such predictions can be used in the choice of therapy, short-term medical treatment for patients with a low risk and long-term medical treatment or, at the appropriate time, a destructive form of therapy for patients with a high risk of relapse.  相似文献   
999.
住院医师临床技能评估方法探讨   总被引:5,自引:0,他引:5  
该文总结了安徽省立医院住院医师培训情况,提出了必须引入实践性考核作为住院医师临床技能考核的主要方式。根据临床技能评价的项目,制定了内科、外科、影像科住院医师临床技能评估指标体系,确立了临床技能考核的原则,并组织实施。这种评估方法能全面考核住院医师的临床技能,但在新的医疗形势下,需建立相关配套措施来保证实施。  相似文献   
1000.
The pentose sugar L-arabinose is one of the most abundant components released by complete hydrolysis of non-starch polysaccharides of feed ingredients of vegetable origin. Two studies were conducted to investigate the apparent ileal digestibility and urinary excretion of L-arabinose at dietary inclusion levels of 50 and 100 g/kg, and 25, 50, 75 and 100 g/kg respectively, in pigs. As a reference, D-glucose was included in the studies. Water intake, ileal flow of volatile fatty acids and ileal and faecal digestibilities of dietary nutrients in pigs fed on the different diets were also examined. Castrated pigs were prepared with a post-valvular T-caecum cannula to measure ileal digestibility. Faecal digestibility was measured in non-cannulated pigs. Apparent ileal digestibility of L-arabinose was found to be approximately 70%. The presence of L-arabinose in the diet increased ileal flow of volatile fatty acids and lactic acid, suggesting the occurrence of microbial degradation of L-arabinose in the pig small intestine. L-arabinose was partly excreted in the urine. The extent of this urinary excretion as a percentage of intake increased linearly (P < 0.01) as the dietary level increased. In pigs fed on the 25 g L-arabinose/kg diet, 10.9% of the L-arabinose consumed appeared in the urine. This level was increased to 14.7% when pigs were fed on a diet containing 100 g L-arabinose/kg diet. Faecal digestibility and retention of nitrogen decreased significantly in pigs fed on the L-arabinose diets.  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