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   9544篇
  免费   453篇
  国内免费   47篇
耳鼻咽喉   82篇
儿科学   189篇
妇产科学   197篇
基础医学   1349篇
口腔科学   163篇
临床医学   878篇
内科学   1582篇
皮肤病学   426篇
神经病学   921篇
特种医学   525篇
外科学   1465篇
综合类   59篇
一般理论   1篇
预防医学   481篇
眼科学   221篇
药学   770篇
中国医学   31篇
肿瘤学   704篇
  2023年   45篇
  2022年   88篇
  2021年   147篇
  2020年   96篇
  2019年   141篇
  2018年   161篇
  2017年   165篇
  2016年   194篇
  2015年   258篇
  2014年   293篇
  2013年   360篇
  2012年   526篇
  2011年   553篇
  2010年   372篇
  2009年   359篇
  2008年   616篇
  2007年   627篇
  2006年   605篇
  2005年   607篇
  2004年   519篇
  2003年   512篇
  2002年   539篇
  2001年   179篇
  2000年   156篇
  1999年   178篇
  1998年   136篇
  1997年   108篇
  1996年   93篇
  1995年   62篇
  1994年   71篇
  1993年   53篇
  1992年   84篇
  1991年   67篇
  1990年   68篇
  1989年   69篇
  1988年   62篇
  1987年   54篇
  1986年   51篇
  1985年   55篇
  1984年   43篇
  1983年   32篇
  1982年   28篇
  1980年   37篇
  1979年   38篇
  1978年   30篇
  1977年   33篇
  1975年   37篇
  1974年   31篇
  1973年   36篇
  1971年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Human brucellosis has become a rare disease in Germany since the eradication of bovine and ovine/caprine brucellosis in this country. Therefore, most physicians are unfamiliar with the illnesses clinical presentation, diagnostic tools, and therapeutic strategies. This retrospective study was carried out to evaluate the epidemiological, clinical, and laboratory features of human brucellosis in Germany in the years 2002 and 2003. Thirty-one bacterial isolates from 30 patients sent to the German national reference laboratory were characterized using the genus-specific bcsp31 real-time PCR, the species-specific AMOS-PCR, and standard microbiological methods for the detection and identification of Brucella spp. The medical records of all patients with bacteriologically confirmed brucellosis were evaluated. All 31 isolates proved to be Brucella (30 Brucella melitensis and 1 Brucella suis). Most of the brucellosis patients were infected in endemic countries while visiting friends and relatives during their summer holidays. One case of laboratory-acquired infection was identified. Brucellosis was transmitted mainly by the consumption of contaminated unpasteurized milk or cheese from goats and sheep. The patients presented primarily with flu-like symptoms, i.e. fever, chills, sweating, headaches, arthralgia, and myalgia. In most cases, however, symptoms and signs of focal complications, e.g. spondylitis, endocarditis, and meningoencephalitis, predominated. The rate of complications was much higher than that in endemic countries, presumably as a result of diagnostic delay due to a low index of suspicion. In summary, physicians in nonendemic countries such as Germany must be aware of brucellosis being a possible cause of fever of unknown origin in immigrants and tourists travelling from endemic countries.  相似文献   
52.
53.
The fine structure of the mature spermatozoon of the pseudophyllidean tapeworm Eubothrium crassum, a parasite of salmonid fishes, has been studied by transmission electron microscopy for the first time. The mature spermatozoon of E. crassum is filiform and tapered at both extremities. It contains two axonemes of unequal length showing the 9 + "1" pattern of Trepaxonemata. The anterior extremity exhibits a crested body 50-100 nm thick. It spirals around the outside of the anterior region of the spermatozoon. The nucleus is electron-dense, exhibiting a fibrous appearance in its middle (the broadest) region. The cortical microtubules are of two types and are situated parallel to the spermatozoon axis. The cytoplasm is slightly electron-dense and contains numerous electron-dense granules in region II of the spermatozoon. A ring of electron-dense, centred microtubules surrounds the axoneme, together with the underlying ring of moderately electron-dense, subjacent submicrotubular material in region V. The anterior and posterior extremities of the spermatozoon lack cortical microtubules and contain a single axoneme. Our results reveal several peculiarities, in which the spermatozoon of E. crassum differs from those of other pseudophyllidean cestodes.  相似文献   
54.
The trisomy 16 mouse model of Down syndrome has been used to compare calcium (Ca)-homeostasis and Ca-signaling in astrocytes from trisomic mice and from diploid littermates. Ratio calcium-imaging of Fura-2/AM loaded primary astroglial cultures prepared from the hippocampus shows that resting Ca levels are on average significantly higher in trisomic than in the control astrocytes (280 vs. 120 nM). Serotonin (3 μM) and glutamate (30–300 μM) evoked transient Ca-increases from 400 to 600 nM in euploid but from only 20 to 150 nM in trisomic astrocytes. Imaging of ATP-driven Ca-accumulation in cellular organelles revealed a significantly stronger uptake of Ca in trisomic astrocytes that might buffer cytosolic Ca-increases. Our results demonstrate major disturbances in Ca-signaling in trisomic astrocytes that are likely to be of pathophysiological relevance.  相似文献   
55.
56.
Erythromycin is frequently prescribed in Germany for acute otitis media, but well-designed clinical trials under present epidemiological conditions are lacking. Therefore, a double-blind, randomized, multicenter trial was performed to compare the clinical efficacy and safety of erythromycin estolate versus amoxicillin in children with acute otitis media and to identify the risk factors associated with clinical failure. Investigators from 19 centers throughout Germany recruited 302 children with clinical, otoscopic, and tympanometric evidence of acute otitis media. In a double-blind fashion, patients were allocated randomly to a 10-day course of erythromycin estolate at 40 mg/kg/day in two divided doses or amoxicillin at 50 mg/kg/day in two divided doses. Clinical examinations, otoscopy, and tympanometry were performed at baseline, day 3–5, day 9–11, and at 5 weeks. Clinical outcome was assessed on day 9–11. Two-hundred eighty children were evaluable for efficacy (erythromycin group, 141; amoxicillin group, 139). Both groups were comparable with respect to demographic data and severity of disease at entry. Treatment was successful in 94% of the erythromycin-treated patients and in 96% of the amoxicillin-treated patients. Clinical outcome was statistically equivalent between groups within a range of 7 percentage points. Clinical recurrence was seen in eight erythromycin-treated children (5.7%) and in seven amoxicillin-treated children (5.0%) (P=0.81). Patients with bilateral disease at entry were at higher risk of unfavourable outcome, whereas age and presence/absence of otorrhea at entry were not associated with outcome. Treatment-related adverse events were recorded in eight (5.3%) of 151 erythromycin-treated patients and in 11 (7.3%) of 151 amoxicillin-treated patients. In this study in an outpatient setting in Germany, erythromycin estolate was as safe and effective as amoxicillin in the treatment of acute otitis media. Both drugs can be administered in a convenient twice-daily dosage schedule.  相似文献   
57.
Synthesis and characterization of methacrylate-monofunctionalized crown ether compounds based on derivatives of 2-hydroxymethyl-1,4,7,10,13-pentaoxacyclopentadecane and 4′-hydroxymethyl-1,4,7,10,13-pentaoxabenzocyclopentadecane is described. By differential scanning calorimetry (DSC) and thermooptical analysis (TOA) it is shown that the synthesized compounds and their sodium triflate complexes exhibit columnar mesophases.  相似文献   
58.
Immunoblot analysis of the serological response in Hantavirus infections   总被引:3,自引:0,他引:3  
Sera from patients with nephropathia epidemica (NE) or Korean hemorrhagic fever (KHF) were tested for specific antibody response to antigens of H?lln?s virus and Hantaan virus strain 76-118. A Vero E6 derived cell line persistently infected with H?lln?s virus strain B1, and Vero E6 cells freshly infected with Hantaan virus type strain 76-118 were used as antigens in the immunofluorescence assay (IFA) and the immunoblot. Blots were prepared from whole cell lysates. The convalescent-phase sera of NE patients tested in this study regularly revealed a marked reaction with a 52 kilodalton (Kd) protein of H?lln?s virus and a 50 Kd protein of Hantaan virus. A convalescent serum from a patient with Korean hemorrhagic fever and a rat antiserum against Hantaan virus could recognize the 50 Kd band of Hantaan virus but showed no apparent reactivity with the 52 Kd component of H?lln?s virus in the standard dilutions. Some sera could additionally identify minor bands in the 55 Kd and/or 67 Kd region of the blots. A one-way cross reactivity between Hantaan and H?lln?s viruses was also evident from the results of the immunofluorescence assays in that NE convalescent sera reacted with both viruses, whereas KHF convalescent or anti-Hantaan sera gave strongly positive results with Hantaan virus but only faint reaction with H?lln?s virus.  相似文献   
59.
The molecular epidemiology of molluscum contagiosum virus (MCV) infections was investigated by restriction endonuclease analysis of the genomes of 222 separate isolates collected from 147 patients living in Germany (33 patients), Hong Kong (6 patients), and Scotland (108 patients). MCV type 1 (MCV-1) caused 96.6% of the infections, and MCV type 2 (MCV-2) caused 3.4%. However, isolates from four of the 142 MCV-1-infected patients and two of the five MCV-2-infected patients showed minor differences in their DNA restriction patterns because of the loss of a single or very few recognition sites for the enzymes used. No genome variations were detected amongst isolates collected from different sites or on several occasions from individual patients or from closely related patients. Southern blot hybridization revealed a high level of relatedness between MCV-1 and 2. No differences were seen in the appearance or anatomical localization of lesions caused by either virus type. In particular, there was no preferred genital localization for MCV-2 infections.  相似文献   
60.
The authors investigated the influence of human body inhomogeneities such as the lungs, blood masses and the skeletal muscle layer on the electrical body surface potential and the magnetic field. The surface potentials and magnetic fields are calculated using a boundary element method. As a rule the blood masses have a large influence on both potential and magnetic field amplitude as well as on the potential and magnetic field map orientation, but the influence on the topology of the map is less in the electric case than in the magnetic case. The single-dipole reconstruction was applied to estimate the error caused by neglecting inner inhomogeneities in source localization. The neglect of lungs and blood masses results in a localization error of less than 1 cm in the electric case but more than 1 cm for deep sources at the posterior side of the heart in the magnetic case. The authors tried to assess the influence of the skeletal muscle layer by both an analytical two-layered anisotropic half-space model and the torso extension method. The skeletal muscle layer causes a smoothing effect on the electrical surface potential and to a lesser extent on the magnetic field, leading to an overestimation of the actual source depth of about 1-2 cm. In principle this can be reduced by taking data from all over the thoracic surface. The authors designed experiments for simultaneous measurement of body surface potential and extracorporeal magnetic field from the same subject. The evaluation of data from two patients showing Wolff-Parkinson-White syndrome has shown that localization results from electric potential data and magnetocardiographic data are consistent.  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