全文获取类型
收费全文 | 1640391篇 |
免费 | 124749篇 |
国内免费 | 3885篇 |
专业分类
耳鼻咽喉 | 23617篇 |
儿科学 | 50195篇 |
妇产科学 | 47899篇 |
基础医学 | 234004篇 |
口腔科学 | 47321篇 |
临床医学 | 140176篇 |
内科学 | 322496篇 |
皮肤病学 | 34057篇 |
神经病学 | 132035篇 |
特种医学 | 66405篇 |
外国民族医学 | 490篇 |
外科学 | 257919篇 |
综合类 | 40408篇 |
现状与发展 | 2篇 |
一般理论 | 499篇 |
预防医学 | 123450篇 |
眼科学 | 38238篇 |
药学 | 120060篇 |
中国医学 | 3174篇 |
肿瘤学 | 86580篇 |
出版年
2018年 | 15366篇 |
2015年 | 15383篇 |
2014年 | 22056篇 |
2013年 | 33979篇 |
2012年 | 45349篇 |
2011年 | 48069篇 |
2010年 | 28667篇 |
2009年 | 27189篇 |
2008年 | 45820篇 |
2007年 | 49333篇 |
2006年 | 49238篇 |
2005年 | 48522篇 |
2004年 | 46964篇 |
2003年 | 45467篇 |
2002年 | 44159篇 |
2001年 | 71076篇 |
2000年 | 72844篇 |
1999年 | 61984篇 |
1998年 | 18001篇 |
1997年 | 16508篇 |
1996年 | 16254篇 |
1995年 | 15314篇 |
1994年 | 14637篇 |
1993年 | 13748篇 |
1992年 | 50603篇 |
1991年 | 48993篇 |
1990年 | 48019篇 |
1989年 | 46273篇 |
1988年 | 43225篇 |
1987年 | 42563篇 |
1986年 | 40693篇 |
1985年 | 39059篇 |
1984年 | 29770篇 |
1983年 | 25423篇 |
1982年 | 15770篇 |
1981年 | 14201篇 |
1980年 | 13430篇 |
1979年 | 29047篇 |
1978年 | 20724篇 |
1977年 | 17469篇 |
1976年 | 16307篇 |
1975年 | 17773篇 |
1974年 | 21726篇 |
1973年 | 20779篇 |
1972年 | 19758篇 |
1971年 | 18272篇 |
1970年 | 17519篇 |
1969年 | 16694篇 |
1968年 | 15497篇 |
1967年 | 14269篇 |
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
991.
Isolation of Stomatococcus mucilaginosus from drug user with endocarditis. 总被引:4,自引:4,他引:0
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P E Coudron S M Markowitz L B Mohanty P F Schatzki J M Payne 《Journal of clinical microbiology》1987,25(8):1359-1363
Stomatococcus mucilaginosus was isolated from the blood of a patient with endocarditis and a past history of drug abuse and aortic valve replacement. At autopsy, Gram stain of the aortic valve revealed gram-positive cocci. Our isolate was atypical for S. mucilaginosus in that colonies were nonmucoid and nonadherent to agar surfaces. Cellular capsules were demonstrated by light and electron microscopy. Phenotypic characteristics identified by conventional methods as well as profile numbers obtained by using two commercial identification systems for staphylococci, the API Staph-Ident and the dms Staph Trac, are presented. Practical tests that differentiate S. mucilaginosus from the genera Micrococcus and Staphylococcus include growth on nutrient agar containing salt and lysostaphin susceptibility. Additional tests that helped differentiate our isolate from group D streptococci included hydrolysis of L-pyrrolidonyl-beta-naphthylamide and streptococcal serogrouping. 相似文献
992.
A case of puncture wound osteochondritis of the foot caused by CDC group Vd is presented because of the unusual nature of the infecting organism. This organism may be confused with Pseudomonas aeruginosa, the usual pathogen responsible for this type of infection, but does not have a similar antimicrobial susceptibility profile. For this reason, it is important to obtain appropriate culture specimens and to identify and test the susceptibility of bacterial isolates from cases of puncture wound-associated osteochondritis so that optimal therapeutic regimens can be determined. 相似文献
993.
Following surgical correction of chronic aortic regurgitation, left ventricular (LV) volume falls to normal or near normal in most patients; this change generally occurs within the first week after surgery. During the ensuing six months, a significant regression of LV hypertrophy occurs, but most patients do not achieve a normal LV mass. The systolic ejection fraction may increase while the LV end-diastolic pressure almost uniformly falls to normal. Postoperative studies of LV volume mass and function should be aimed at identifying those patients which do not undergo these favorable changes so that medical therapy can be directed at this high risk group. 相似文献
994.
995.
Symptoms of tobacco withdrawal. A replication and extension 总被引:19,自引:0,他引:19
Smokers (n = 315) who wished to quit were randomly assigned in a double-blind manner to groups using either nicotine or placebo gum. Self-reported and observed symptoms of tobacco withdrawal were collected before cessation and at follow-ups of 1 to 2 weeks, 1 month, and 6 months. Self-reported and/or observed anger, anxiety, craving, difficulty concentrating, hunger, impatience, and restlessness were the most prominent symptoms of tobacco withdrawal. These symptoms had returned to precessation levels by 1 month except increased weight, hunger, and craving continued for 6 months in many smokers. Nicotine gum decreased most symptoms, including craving and hunger but not weight. Abstinent smokers with more intense withdrawal were not more likely to relapse. Abstinent smokers who gained more weight were less likely to relapse. 相似文献
996.
Valve-related complications with the Hancock I porcine bioprosthesis. A twelve- to fourteen-year follow-up study 总被引:4,自引:0,他引:4
J M Bernal J M Rabasa J C Cagigas J R Echevarria M F Carrion J M Revuelta 《The Journal of thoracic and cardiovascular surgery》1991,101(5):871-880
Valve-related morbidity and mortality after heart valve replacement with the Hancock I porcine bioprosthesis has been retrospectively analyzed. From June 1974 through December 1976, 253 Hancock I bioprostheses (150 mitral and 103 aortic) were inserted in 220 selected patients who survived the operation and had follow-up until June 1989 (mean follow-up 13.5 years, with an accumulative follow-up of 2956.4 patient-years). One hundred seventeen patients had mitral valve replacement, 70 had aortic valve replacement, and 33 had combined mitral and aortic valve replacement. There were 27 thromboembolic events. The probability of being free from thromboembolism at 14 years was 81.0% +/- 7.4% for the mitral valve replacement group, 85.4% +/- 6.7% for the aortic group, and 67.1% +/- 18.4% for the mitral-aortic group. Fifteen episodes of prosthetic valve endocarditis occurred. There were 10 instances of nonstructural dysfunction (paravalvular leaks) in seven mitral valves (4.6%) and in three aortic valves (2.9%). One hundred twenty-two bioprostheses in 106 patients resulted in structural deterioration. The probability of freedom from structural deterioration at 14 years was 37.2% +/- 3.9% for the mitral group, 43.9% +/- 7.1% for the aortic group, and 30.1% +/- 8.9% for the mitral-aortic group. The logistic regression analysis between age at the time of operation and bioprosthetic life (structural deterioration-free period) demonstrates a linear regression curve (r = 0.53). There were 56 late deaths (27 patients died at reoperation). The actuarial survival rate (including hospital mortality) at 14 years was 57.2% +/- 5.4% for the entire series, with no statistically significant difference between groups. The probability of remaining free from valve-related morbidity and mortality at 14 years was 16.7% +/- 4.8% for the mitral group, 20.8% +/- 6.2% for the aortic group, and 14.0% +/- 7.0% for the mitral-aortic group. The long-term results of this series show that the clinical performance of the Hancock I porcine valve appears satisfactory during the first 6 years. The behavior of this bioprosthesis at 14 years' follow-up changes drastically, because only a minor group of patients is free from valve-related complications, justifying the restriction of its use for selected patients. 相似文献
997.
998.
W. Scharenberg 《Archives of environmental contamination and toxicology》1991,21(4):536-540
Brain, livers, and subcutaneous fat of 50 Cormorants (Phalacrocorax carbo sinensis, Blumenbach 1798) were analyzed for 6 PCB congeners. The birds had been shot in autumn 1985 and 1986 in Schleswig-Holstein, FRG. Subcutaneous fat was the highest contaminated tissue, while brain had accumulated the lowest concentrations. An accumulation by age was statistically significant between the groups of 1st year/2nd year birds and after 2nd year birds. There were no differences evident between sex and between weight groups. Pooled samples were analyzed by GC-MS; 61 congeners could be identified in adipose tissue, 54 in liver, and 49 in brain. 18 congeners were quantified in spotchecks, and some samples were analyzed by multidimensional gaschromatography. In comparison to fish they consume, the fat of cormorants was concentrated with PCBs 10–100 times more than marine fish, and 100–1,000 times more than freshwater fish. This species is a suitable bioindicator for PCBs. 相似文献
999.
alpha 2-Adrenergic receptors (ARs) are involved in central nervous system (CNS) control of blood pressure. It is now known that there are three human genes that encode subtypes of alpha 2-ARs, but little is known regarding the distribution of these subtypes throughout the CNS. The availability of receptor clones allows the mapping of mRNAs encoding the individual alpha 2-AR subtypes in the CNS. In this communication, we report that there are three, closely related rat alpha 2-AR genes. We have developed subtype-specific hybridization probes from each of these genes and have used these reagents to measure alpha 2-AR subtype mRNA accumulation in extracts of discrete regions of the rat CNS. We found that mRNAs encoding the alpha 2A-AR and alpha 2C-AR subtypes are distributed widely, but unevenly, throughout the rat CNS. The A subtype is prominent in the midbrain, brainstem, spinal cord, pituitary and diencephalon while the C subtype predominates in basal ganglia and cerebellum. The cortex, olfactory bulb and hippocampus contain roughly equal amounts of the alpha 2A- and alpha 2C-AR mRNAs. A third subtype's (alpha 2B-AR) mRNA is far less abundant in brain tissues, and is only found in the diencephalon. 相似文献
1000.