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   791篇
  免费   36篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   19篇
妇产科学   15篇
基础医学   77篇
口腔科学   26篇
临床医学   64篇
内科学   151篇
皮肤病学   6篇
神经病学   97篇
特种医学   51篇
外科学   135篇
综合类   11篇
预防医学   36篇
眼科学   5篇
药学   80篇
肿瘤学   48篇
  2023年   7篇
  2022年   6篇
  2021年   21篇
  2020年   15篇
  2019年   13篇
  2018年   20篇
  2017年   10篇
  2016年   15篇
  2015年   20篇
  2014年   30篇
  2013年   27篇
  2012年   60篇
  2011年   58篇
  2010年   31篇
  2009年   27篇
  2008年   42篇
  2007年   37篇
  2006年   33篇
  2005年   37篇
  2004年   39篇
  2003年   36篇
  2002年   19篇
  2001年   17篇
  2000年   22篇
  1999年   14篇
  1998年   10篇
  1997年   12篇
  1996年   7篇
  1995年   6篇
  1994年   5篇
  1993年   3篇
  1992年   19篇
  1991年   23篇
  1990年   18篇
  1989年   8篇
  1988年   5篇
  1987年   14篇
  1986年   11篇
  1985年   7篇
  1984年   4篇
  1983年   4篇
  1982年   3篇
  1981年   4篇
  1979年   3篇
  1978年   2篇
  1976年   1篇
  1974年   1篇
  1965年   1篇
  1943年   1篇
排序方式: 共有828条查询结果,搜索用时 46 毫秒
101.
102.
Carcinoids are rare tumour of neuroendocrin origin, characterized by argyrophylic silver stain reaction, positive immunohistochemical reaction with neuron-specific markers, a typical growth pattern; they can express different peptides and biogenic amines. Gastric carcinoid tumours have been classified on the basis of susceptibility to gastric trophic stimulus and characteristics mucosal surrounding into 3 different types. This classification is important with respect to therapeutic strategy (type adapted treatment), but the option of endoscopic or surgical treatment is influenced by the impossibility to distinguish clearly the benignity or malignity of these lesions. A review of international literature and a rare case of gastric carcinoid tumour associated with chronic athrophic gastritis, developed in a female 65-years old, with anaemia and treated by subtotal gastrectomy, are presented.  相似文献   
103.
In a prospective side-by-side comparison conducted from September through November 1994, we compared the MicroScan WalkAway system, a conventional biochemical identification system (Dade MicroScan, Inc., Sacramento, Calif.), with the Vitek system (bioMerieux Vitek, Hazelwood, Mo. [analysis software version AMS-RO8.2] for the identification of gram-negative bacteria. Three-hundred thirty-one nonurine isolates and 493 urine isolates were tested. For nonurinary isolates, there was 91.5% agreement between the two methods. For urinary isolates, there was 97.4% agreement between the two methods. Overall, there was 95% agreement between the two systems. The results suggest that the current version of the MicroScan WalkAway system with conventional panels is essentially comparable to the current Vitek system.  相似文献   
104.
105.
The aim of this study was to evaluate the degree of tooth wear in posterior deciduous teeth of 100 subjects in the second phase of mixed dentition who were born in the 1950s (50sG) and 100 subjects born in the 1990s (90sG). The degree of abrasion for each posterior deciduous tooth was scored ranging from 0 to 3. The comparison of the degree of abrasion showed significant differences between the two groups for all examined teeth (upper and lower deciduous canines and first and second primary molars) all of which appeared to be more abraded in the 50sG. The findings of the present study indicate that subjects who were born in the 1950s exhibited a significantly greater degree of tooth wear on the posterior deciduous teeth when compared with contemporary subjects, along with a well-recognized lower prevalence of malocclusions. Changes in dietary habits and a diet based on processed foods may be postulated as factors involved with a decrease of dental attrition in contemporary populations. An increase in the prevalence of mouth breathing (tested in the present study) appears to be associated with a decrease in tooth wear in the contemporary population as well.  相似文献   
106.
The aim of this study was to evaluate the effect of the Heat Shock Proteins GroES, GroEL and DnaK on the expression of the costimulatory molecules CD80/CD86 in B cells and macrophages. The interactions among these molecules are able to highly influence the immune response through the regulation of cytokine liberation which, on their own, are able to regulate the immunological response by a feedback mechanism. Our results showed that, on B cells, GroES and GroEL stimulated the expression of CD86 but did not induce the increase of the CD80 expression. CD86 peak expression showed a peak after 24-48 h of culture and decreased 60h after the stimulation. GroES and GroEL also stimulated the expression of CD80 and CD86 on macrophages. The same HSPs did not modify the expression of CD80 and CD86 on cells having characteristics of activated macrophages, the A-THP-1 cell line. DnaK did not induce any increase in the expression of CD80 and CD86 on lymphocytes or macrophages.  相似文献   
107.
The cyclic somatostatin analogue cyclo[Pro(1)-Phe(2)-D-Trp(3)-Lys(4)-Thr(5)-Phe(6)] (L-363,301) displays high biological activity in inhibiting the release of growth hormone, insulin, and glucagon. According to the sequence of L-363,301, we synthesized a number of cyclic hexa- and pentapeptides containing nonnatural alpha- and beta-amino acids. The N- fluorenylmethoxycarbonyl protected cyclic beta-amino acid [1S, 2S, 5R]-2-amino-3,5-dimethyl-2-cyclohex-3-enecarboxylic acid (cbetaAA), for the replacement of the Phe(6)-Pro(1) moiety of L-363,301, was synthesized in two steps by an enantioselective multicomponent reaction using (-)-8-phenylmenthol as a chiral auxiliary. The resulting peptide cyclo[cbetaAA(1)-Tyr(2)-D-Trp(3)-Nle(4)-Thr(Trt)(5)] (Trt = triphenylmethyl) shows high antiproliferative effects in an in vitro assay with A431 cancer cells. The same peptide without the Trt group does not reveal any biological activity, whereas L-363,301 and closely related hexapeptides show only minor activity. By comparison of the solution structure of cyclo[cbetaAA(1)-Tyr(2)-D-Trp(3)-Nle(4)-Thr(Trt)(5)] with the structure of l-363,301, a nearly perfect match of the betaII'-turn region with d-Trp in the i + 1 position was observed. The cyclic beta-amino acid cbetaAA is likely needed for the bioactive conformation of the peptide.  相似文献   
108.
Although developmental dyslexia is often referred to as a cross-modal disturbance, tests of different modalities using the same stimuli are lacking. We compared the performance of 23 children with dyslexia and 42 chronologically matched control readers on reading versus repetition tasks and visual versus auditory lexical decision using the same stimuli. With respect to control readers, children with dyslexia were impaired only on stimuli in the visual modality; they had no deficit on the repetition and auditory lexical decision tasks. By applying the rate-amount model (Faust et al., 1999), we showed that performance of children with dyslexia on visual (but not auditory) tasks was associated with that of control readers by a linear relationship (with a 1.78 slope), suggesting that a global factor accounts for visual (but not auditory) task performance.We conclude that the processing of linguistic stimuli in the visual and auditory modalities is carried out by independent processes and that dyslexic children have a selective deficit in the visual modality.  相似文献   
109.
Introduction Distal biceps tendon rupture is a relatively rare injury. It commonly occurs in the dominant extremity of middle-aged men during an excessive eccentric tension as the arm is forced from a flexed position, while it is rarely observed during sport activities. Many techniques, including non-operative and surgical option, have been described for the treatment of a ruptured distal biceps tendon, but there is still considerable controversy about the management of choice. Material and methods Nine patients affected with traumatic distal tendon ruptures of the biceps brachii were followed-up for a minimum of 24 months. Five patients underwent surgery (two-incision technique) and four patients were treated conservatively. Tendon readaptation to its origin was done by a suture metal anchor. Outcome was evaluated based on the physical examination, radiographic analysis and the SECEC elbow score. Results The SECEC elbow score results show that every single item result is in favour of surgical treatment. On measurements of motion, we found a slight flexion–extension deficit in two patients, but reduced supination in six patients and reduced pronation in four. Two patients had postoperative dysfunction of the deep branch of the radial nerve. Radiographic examination showed heterotopic bone formation on the radial tuberosity around the presumed insertion of the reattached tendon in 2 of 5 patients and ectopic ossification more proximally in the area of the biceps muscle Conclusion Our findings confirm the view that anatomic repair of distal biceps tendon rupture provides consistently good results and early anatomic reconstruction can restore strength and endurance for the elbow.  相似文献   
110.
Unsteadiness, dizziness and vertigo occur more frequently in hypertensive subjects, compared to the normal ones. This study evaluated the influence of hypertension on balance tests, performed on posturographic platform. The study pool consisted of 112 persons aged 65 and older (65 hypertensives), their mean age was 72.9+/-0.5, scored on the Mini Mental State Examination (MMSE) greater than 24, were able to perform self-care activities, to walk independently for at least 400 m and were free from major diseases. Subjective dizziness and vertigo were assessed by means of Sickness-Impact-Profile-Questionnaire (SIPQ). The static posturographic tests were performed on a vertical force platform, from which the center of foot pressure (COP) positions and displacements were recorded. In balance tests three standardized positions were utilized: feet 30 degrees apart, semitandem and tandem. Subjects with hypertension complained more frequently dizziness and vertigo (41.5% vs. 21.3%). The track-length and COP-velocity were associated with age in all the balance tests. In semitandem and tandem positions, the medio-lateral sway distance significantly increased in elderly subjects compared to young controls. No difference, however, was found in balance tests between normotensive and hypertensive subjects. Those with uncomplicated hypertension compared with normo-tensive subjects, although complaining more frequently symptoms of postural instability, did not show worse performances in static posturographic tests.  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