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   1731篇
  免费   43篇
  国内免费   8篇
耳鼻咽喉   12篇
儿科学   20篇
妇产科学   12篇
基础医学   223篇
口腔科学   57篇
临床医学   123篇
内科学   409篇
皮肤病学   20篇
神经病学   155篇
特种医学   79篇
外科学   195篇
综合类   9篇
预防医学   156篇
眼科学   41篇
药学   140篇
中国医学   2篇
肿瘤学   129篇
  2023年   6篇
  2022年   19篇
  2021年   30篇
  2020年   15篇
  2019年   11篇
  2018年   23篇
  2017年   17篇
  2016年   30篇
  2015年   21篇
  2014年   37篇
  2013年   56篇
  2012年   98篇
  2011年   103篇
  2010年   67篇
  2009年   78篇
  2008年   113篇
  2007年   136篇
  2006年   106篇
  2005年   106篇
  2004年   121篇
  2003年   109篇
  2002年   103篇
  2001年   23篇
  2000年   26篇
  1999年   25篇
  1998年   24篇
  1997年   20篇
  1996年   18篇
  1995年   19篇
  1994年   10篇
  1993年   12篇
  1992年   13篇
  1991年   13篇
  1990年   13篇
  1989年   19篇
  1988年   4篇
  1987年   11篇
  1986年   11篇
  1985年   13篇
  1984年   12篇
  1983年   3篇
  1982年   5篇
  1981年   9篇
  1980年   7篇
  1978年   4篇
  1977年   7篇
  1976年   9篇
  1975年   5篇
  1959年   4篇
  1958年   5篇
排序方式: 共有1782条查询结果,搜索用时 31 毫秒
1.
Increasing numbers of arthroplasties are also accompanied by postoperative infections. The main purpose was to evaluate preoperative serum bilirubin levels between patients with and without infections after shoulder and knee arthroplasties. For this retrospective case-control single-center study, a total of 108 patients were extracted from a prospectively collected database. Eighteen patients with infections after shoulder (n = 8) and knee (n = 10) arthroplasty were matched by age, gender, and implant type in a 1:5-scenario to 90 patients (40 shoulders and 50 knees) without postoperative infection. Demographic data, preoperative blood parameters, and postoperative infection-related outcomes were evaluated. Total bilirubin was the only preoperative parameter significantly different between the infection (8.21 ± 3.25 μmol/L or 0.48 ± 0.19 mg/dL) and noninfection (10.78 ± 4.62 μmol/L or 0.63 ± 0.27 mg/dL; P = .014) group, while C-reactive protein and other liver parameters were similar between the groups. Significantly more controls (92.1%) had preoperative bilirubin levels above 8.72 μmol/L or 0.51 mg/dL than cases (7.9%; P = .007). The 5-year infection survival-rate was 65.6% for patients with preoperative bilirubin levels < 8.72 μmol/L or < 0.51 mg/dL and 91.2% with ≥ 8.72 μmol/L or ≥ 0.51 mg/dL. Mildly decreased preoperative bilirubin levels with a cutoff at 8.72 μmol/L or 0.51 mg/dL were significantly associated to patients with infections after shoulder and knee arthroplasty. There were no differences in other blood parameters or comorbidities between patients with infections and their matched-controls.  相似文献   
2.
OBJECTIVES: To assess prospectively the early time course of Transforming Growth Factor beta-1 (TGFbeta-1), basic Fibroblast Growth Factor (bFGF) and Tumor Necrosis Factor alpha (TNFalpha) as possible contributors to restenosis development after angioplasty. DESIGN: Prospective Study. METHODS: The levels of the soluble forms of these factors in the early response to Percutaneous Transluminal Angioplasty (PTA) in the arteries of the lower limb were prospectively assessed. 32 patients with peripheral arterial occlusive disease (PAOD), presenting with intermittent claudication (Fontaine stage IIb) were scheduled for angioplasty treatment. Serum levels of TGFbeta-1, TNFalpha and bFGF were assessed before intervention, 15 and 60 minutes after, 24 hours after as well as 2 and 4 weeks after intervention. We compared the distribution patterns between patients treated with balloon angioplasty and patients who required secondary stent implantation. Endpoint was the development of restenosis within 6 months after interventional treatment, defined as a lumen diameter reduction of more than 50% by ultrasound measurement compared to the result after PTA. RESULTS: The patients who later developed restenosis had significantly higher levels of TGFbeta-1 at 15 minutes, 24 hours and 2 weeks after PTA (p<0.05). TNFalpha and bFGF were only detected in a few patients and no significant change of serum levels was observed. CONCLUSION: The results demonstrate a possible role of TGFbeta-1 in the formation of restenosis after PTA.  相似文献   
3.
Migraine is considered to be a functional neurological disorder. In classical migraine (headache associated with prodromal visual field disturbances) and migraine accompagnée (headache associated with transient neurological symptoms), disturbances of cerebral blood flow and amine metabolism are thought to be pathogenetic factors. However, conventional methods of neuroimaging (CAT, NMR) usually do not yield any pathological findings in patients. Since 123I-iodoamphetamine (123I-IMP) crosses the intact blood brain barrier, 123I-IMP-SPECT is used for the assessment of cerebral perfusion in various neurological diseases, including functional disorders. 123I-IMP-SPECT was performed on 5 patients with classical migraine and 18 patients with migraine accompagnée. At the time of investigation, all patients were symptom-free. Cerebral blood flow was decreased in all patients with migraine accompagnée, and often corresponded to the site of headache as well as to the topography of transient neurological symptoms. This reduction was most obvious in a patient with persisting neurological symptoms. Most patients with classical migraine, however, did not show any alteration of cerebral perfusion. It appears that migraine--and in particular migraine accompagnée--is characterized by a permanent alteration not only of cerebral blood flow but also of neuronal activity. Migraine attacks may occur in connection with exacerbations of preexisting metabolic alterations.  相似文献   
4.
AIMS: This study evaluates feasibility, safety, and efficacy of magnetic remote-controlled accessory pathway (AP) ablation. METHODS AND RESULTS: The novel magnetic navigation system (MNS) (Niobe, Stereotaxis) creates a steerable magnetic field (0.08 T) controlling the distal magnetic tip of an ablation catheter. In conjunction with a catheter advancer system (Cardiodrive, Stereotaxis) remote catheter ablation is enabled. Conventional electrophysiology study identified AP conduction in 59 patients (37 males, 36+/-14 years, 60 APs). First generation 1-magnet tip (1-M) (group I, n=18), second generation bipolar 3-magnet tip (3-M) (group II, n=27), and third generation quadripolar 3-magnet tip catheters (3-M quad.) (group III, n=14) were used for magnetic remote-controlled ablation. Successful AP ablation was achieved in 67% (group I), 85% (group II), and 92% (group III). A significant decrease of median [IQR: Q1-Q3] fluoroscopy time and dosage was observed: 21.2 [12.1-33.8] min, 1110 [395-3234] microGym2 (group I); 6.5 [4.4-15.4] min, 290 [129-489] microGym2 (group II), and 4.9 [3.4-8.0] min, 129 [74-270] microGym2 (group III). Mean procedure time (217+/-67 min; 182+/-68 min, and 172+/-90 min) significantly decreased in group III. Median number [Q1-Q3] of radiofrequency current applications in groups I, II, and III was 4 [2-9], 4 [2-6], and 2 [2-4], respectively. No complications occurred. CONCLUSION: Remote AP ablation is safe and feasible using the novel MNS. Introduction of the 3-magnet quadripolar ablation catheter significantly improved the efficacy of the procedure.  相似文献   
5.
6.
7.
The dermatologist's procedure was introduced in 1972 by employers' liability insurance funds in the industrial, agricultural and public sectors of Germany's statutory occupational accident insurance as a "procedure for early detection of occupational skin diseases". So far, it is still the most relevant tool for secondary prevention in occupational dermatology in Germany. According to the intention of this procedure, insured persons with a skin disease in which an occupational aetiology is suspected must be offered preventive measures and, if necessary, given appropriate treatment to avoid their losing their jobs. On the initiative of the Central Federation of Industrial Professional Associations (HVBG), a study group was set up in 1999 from among its membership in cooperation with the Working Committee of Occupational and Environmental Dermatology (ABD) and the Professional Organisation of German Dermatologists (BVDD) to improve on the efficiency of the "classic" dermatologist's procedure. The proposed "optimised" dermatologist's procedure is based on the assumption that early detection followed by competent and intensified skin protection and skin care will be successful in retarding or stopping the progression of occupational dermatoses, while later treatment is likely to be less effective. In October 2002, a pilot study started in Northwest Germany to establish by scientific evaluation whether the implementation of secondary protective measures is definitively better when the provisional "optimised" dermatologist's procedure is followed. The study results should allow detailed suggestions for an improved dermatologist's procedure before it is introduced nationwide.  相似文献   
8.
9.
A group of 24 patients with Parkinson's disease (PD) with normal fundi and normal visual acuities was examined electrophysiologically. Checkerboard reversal VEPs and ERGs (P-ERGs) at various contrast levels as well as photopic and scotopic luminance ERGs were recorded and compared with an age-matched group of controls. Earlier reported latency increases of the VEPs of the patients were confirmed for patterns of high contrast only. Scotopic and photopic luminance ERGs of the patients showed normal latencies, but at all light intensities the amplitudes of the scotopic and photopic b wave, as well as the amplitudes of the photopic a waves, were significantly reduced, P-ERG amplitudes were reduced at 50% contrast. Identical results were obtained in patients under dopaminergic treatment (n = 17) and in patients who did not receive any treatment (n = 7). These results suggest that alterations occur already at the retinal level where dopamine receptors have been found. Thus the reported changes of the VEP are not caused by the visual cortex alone.  相似文献   
10.
In the differentiated state, the testicular excurrent duct system of the sturgeon begins as a longitudinal marginal network of the testis, extending along the entire length of the male gonad. From here, mesorchial transversal ducts travel to the ventral aspect of the pars sexualis of the opisthonephros where they merge behind the dorsal coelomic wall to form the longitudinal marginal network of the kidney. Then, the seminal pathways enter the confines of the pars sexualis of the opisthonephros and divide into a complicated, multipartite system consisting of (1) centropapillary ducts, situated in the center of a group of urinary collecting ducts, (2) lacunary basal sinuses, located on the bases of opisthonephric columns and (3) intracolumnar ducts running inside the renal columns, the latter representing typical functional units of the adult sturgeon kidney. The contacts between intracolumnar ducts and the vascular poles of corresponding renal corpuscles represent the urogenital junction in the sturgeon. The nephrons of the pars sexualis involved in sperm transport do not lose their urinary functions, but are histologically identical to those of the pars excretoria which are solely urinary. The opisthonephros of sturgeons grows continuously by the formation of new nephrons from an opisthonephric blastema located on the base of each renal column. A close topographical association between this blastema tissue and the lacunary basal sinuses of the testicular excurrent duct system guarantees that new renal corpuscles in the pars sexualis are included in the seminal passage from their beginning. From the urogenital junctions, on their way to the exterior, the spermatozoa have to travel through Bowman's capsules and tubules of the nephrons involved, then through the urinary collecting ducts, the wolffian duct and finally the sinus urogenitalis. The development of the testicular excurrent duct system begins in 8-month-old animals in the pregonadal area of the gonadal fold. Here, a primary gonoductal blastema proliferates to form a longitudinal network of anastomosing strands, situated in the dorsal mesogonadal attachment. From this primary longitudinal network, small tubules grow into the direction of the opisthonephros and into the direction of the testis. In the period from 8 to 18 months, the testicular excurent duct system reaches the adult state. In conclusion, the testicular excurrent ducts of sturgeons initially develop similar to those of Polypterus and in modern teleosts from a primary longitudinal system, beginning in the pregonadal area, localized in the mesogonadal attachment and extending caudally. Then, in a second step of development, the phylogenetically older situation, using parts of the kidney as passage, already seen in Chondrichthyes, but preserved also in higher vertebrates, is achieved in Acipenser. For this, seminal ducts grow into the opisthonephros and establish here the urogenital junctions with corresponding renal corpuscles. Furthermore, the initially longitudinally oriented ducts in the mesogonadal attachment partly lose their continuity and become integrated into the course of the transversal mesorchial ducts, represented by their portions with the widest lumina and the thickest walls.  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