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   235230篇
  免费   11154篇
  国内免费   407篇
耳鼻咽喉   3055篇
儿科学   7302篇
妇产科学   4769篇
基础医学   33810篇
口腔科学   5350篇
临床医学   18641篇
内科学   51869篇
皮肤病学   6230篇
神经病学   21016篇
特种医学   7104篇
外国民族医学   101篇
外科学   29130篇
综合类   1002篇
一般理论   66篇
预防医学   21395篇
眼科学   4608篇
药学   16544篇
中国医学   703篇
肿瘤学   14096篇
  2023年   1250篇
  2022年   894篇
  2021年   3495篇
  2020年   2093篇
  2019年   3931篇
  2018年   7462篇
  2017年   4903篇
  2016年   4888篇
  2015年   5466篇
  2014年   5741篇
  2013年   9257篇
  2012年   16066篇
  2011年   16025篇
  2010年   8013篇
  2009年   6007篇
  2008年   13772篇
  2007年   14766篇
  2006年   13595篇
  2005年   13466篇
  2004年   12620篇
  2003年   11513篇
  2002年   10901篇
  2001年   6144篇
  2000年   6230篇
  1999年   5560篇
  1998年   933篇
  1997年   775篇
  1996年   722篇
  1992年   3211篇
  1991年   2889篇
  1990年   2745篇
  1989年   2503篇
  1988年   2372篇
  1987年   2196篇
  1986年   2098篇
  1985年   1890篇
  1984年   1400篇
  1983年   1194篇
  1982年   672篇
  1979年   1205篇
  1978年   848篇
  1977年   796篇
  1975年   801篇
  1974年   986篇
  1973年   1000篇
  1972年   938篇
  1971年   925篇
  1970年   863篇
  1969年   909篇
  1968年   788篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Résumé: La rémission du cancer peut être l’occasion pour certains patients d’une réelle détresse émotionnelle ainsi que d’une désadaptation psychologique appelées: syndrome de Lazare. Nous émettons trois hypothèses explicatives quant à la survenue de tels troubles. La première confronte l’issue du cancer aux concepts psychanalytiques de dette et de masochisme. La deuxième envisage les symptômes sous l’angle d’une réaction de sevrage. Et la dernière évoque le contrecoup traumatique des traitements.Dossier: «Cliniques du cancer»  相似文献   
52.
We report the identification of a new transthyretin (TTR) gene mutation and variant protein, Glu61Gly, in a 55-year-old man with progressive cardiomyopathy, mild peripheral neuropathy and bilateral carpal tunnel syndrome. A diagnosis of TTR-associated familial amyloidosis (ATTR) was considered after an endomyocardial biopsy revealed amyloid deposits in the heart of a patient who had no family history of amyloidosis and no evidence of a plasma cell dyscrasia. Serum screening for a TTR variant by isoelectric focusing (IEF) was positive and prompted further studies to identify the genetic abnormality and to characterize the amyloidogenic protein. Direct DNA sequence analysis of all four coding regions in the TTR gene demonstrated heterozygosity in exon 3. Near equal amounts of guanine (G) and adenine (A) were observed at the second base position of codon 61. The wild-type (GAG) and mutated (GGG) sequences found in codon 61 correspond to glutamic acid (Glu) and glycine (Gly) residues, amino acids which differ in mass by -72 Da. Mass spectrometric analyses of TTR immunoprecipitated from serum showed the presence of both wild-type and variant proteins. The observed mass results for the wild-type and variant proteins were consistent with the predicted values calculated from the genetic analysis data.  相似文献   
53.
In the first experiment, 52 sows, each having raised one litter, were randomly assigned to the five following groups: control (nongravid) for pregnancy (CP), 110 d pregnancy (P110), control (nongravid) for lactation (CL), 4-wk lactation with 8 (L8) and with 12 (L12) piglets. In a second experiment, 36 sows, each having raised three litters, were randomly assigned to the following groups: control group (nongravid) fed a low-energy-density, 1% tallow diet (CLED) and two lactating groups, one fed the low-energy-density diet (LLED) and one fed a high-energy-density, 10% tallow diet (LHED). At slaughter, the stomach, small and large intestine and cecum were excised, emptied and freed from fat. Lengths and pre- and post-defatting weights were measured. Portions of tissues were homogenized and analyzed for protein, pepsin, maltase, RNA and DNA. Pregnancy had no effect on the weights of the different components of the gastrointestinal tract. Liver and small intestine weights were larger in lactating sows than in the CL group. Sows nursing 12 piglets had heavier livers than those nursing 8. The fundic mucosa of the latter had higher total pepsin activity and total protein and RNA contents than that of L12 sows. LHED sows had heavier small intestine and lower total pepsin content of the fundic mucosa than LLED sows.  相似文献   
54.
Gallibacterium anatis (previously named Pasteurella haemolytica-like) is considered a normal inhabitant of genital and upper respiratory tracts of healthy chickens, but it is also associated with different pathological conditions. Secreted metalloproteases from field and reference G. anatis cultures were obtained by methanol precipitation and were characterized. Proteins of molecular mass higher than 100 kDa showing proteolytic activity were observed in 10% polyacrylamide gels copolymerized with 1% bovine casein. They were active at alkaline pH, and inhibited by ethylenediamine tetraacetic acid. Their activity was stable at 50 degrees C, but partially inhibited at 60 degrees C, and totally inhibited at higher temperatures. Secreted proteins were able to degrade chicken IgG after 24 h of incubation, and cross-reacted with a polyclonal antibody against purified protease from Actinobacillus pleuropneumoniae. Secreted metalloproteases could play a role in infections caused by G. anatis.  相似文献   
55.
56.

Introduction  

This paper presents the results of a study on the psychometric properties of an authorized Spanish version of the McMaster Family Assessment Device, a self-report measure of family functioning.  相似文献   
57.
58.

Background  

Advances in intensive care medicine have increased survival rates of patients with critical neurological conditions. The focus of prognostication for such patients is therefore shifting from predicting chances of survival to meaningful neurological recovery. This study assessed the variability in long-term outcome predictions among physicians and aimed to identify factors that may account for this variability.  相似文献   
59.
Background Chromium allergy has traditionally been caused by occupational skin contact with cement. In 1983, Danish legislation made the addition of ferrous sulphate compulsory in cement to reduce the water‐soluble chromium content to not more than 2 ppm. An effect from this intervention has previously been demonstrated among Danish construction workers. Objectives To investigate the development of chromium allergy among patients with dermatitis tested between 1985 and 2007 in Denmark. Furthermore, to determine causative exposures in patients with chromium allergy. Patients and methods A retrospective analysis of patch test data was performed (n = 16 228) and charts from patients with chromium allergy were reviewed. Comparisons were made using a χ2 test. Logistic regression analyses were used to test for associations. Results The prevalence of chromium allergy decreased significantly from 3·6% in 1985 to 1% in 1995 (Ptrend < 0·001) but increased to 3·3% in 2007 (Ptrend < 0·001). The frequency of clinically relevant cement exposure decreased significantly among patients with chromium allergy from 12·7% in 1989–1994 to 3·0% (P < 0·01) in 1995–2007, whereas the frequency of relevant leather exposure increased significantly from 24·1% during 1989–1994 to 45·5% during 1995–2007 (P < 0·02). Conclusions Chromium allergy is currently increasing in Denmark due to leather exposure.  相似文献   
60.
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