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   178701篇
  免费   1012篇
  国内免费   32篇
耳鼻咽喉   1303篇
儿科学   6820篇
妇产科学   3195篇
基础医学   16636篇
口腔科学   1644篇
临床医学   12632篇
内科学   31537篇
皮肤病学   723篇
神经病学   16595篇
特种医学   9132篇
外科学   29625篇
综合类   2360篇
预防医学   18098篇
眼科学   2836篇
药学   9565篇
中国医学   629篇
肿瘤学   16415篇
  2023年   28篇
  2022年   52篇
  2021年   95篇
  2020年   55篇
  2019年   85篇
  2018年   22000篇
  2017年   17431篇
  2016年   19602篇
  2015年   1016篇
  2014年   959篇
  2013年   978篇
  2012年   7214篇
  2011年   21224篇
  2010年   18944篇
  2009年   11626篇
  2008年   19722篇
  2007年   21946篇
  2006年   827篇
  2005年   2461篇
  2004年   3617篇
  2003年   4507篇
  2002年   2587篇
  2001年   326篇
  2000年   443篇
  1999年   179篇
  1998年   214篇
  1997年   218篇
  1996年   102篇
  1995年   102篇
  1994年   104篇
  1993年   62篇
  1992年   41篇
  1991年   89篇
  1990年   125篇
  1989年   76篇
  1988年   53篇
  1987年   40篇
  1986年   21篇
  1985年   31篇
  1983年   23篇
  1982年   24篇
  1980年   40篇
  1969年   20篇
  1939年   20篇
  1938年   60篇
  1937年   25篇
  1935年   22篇
  1934年   30篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The aim of this study was to estimate the prevalence of lower urinary tract symptoms (LUTS) among female elementary school teachers in Taipei. A total of 520 self-administered surveys were distributed to 26 elementary schools in Taipei City. Data analyses were based on 445 usable surveys. The prevalence rates for different types of LUTS ranged from 9.9 to 44.5%. The prevalence of urinary incontinence (UI; 26.7%) and nocturia (16.0%) fell within the prevalence estimates of these LUTS in North American and European women. Employed women in this study were more likely to experience LUTS than women in previous epidemiological or community studies. This study extended research on UI into other LUTS among employed women in Asia. Study results suggest that the working environment may affect LUTS in female elementary school teachers. This preliminary study is important for developing future behavioral interventions for female LUTS in the workplace.  相似文献   
992.
Malaria infections repeatedly have been reported to induce nephrotic syndrome and acute renal failure. Questions have been raised whether the association of a nephrotic syndrome with quartan malaria was only coincidental, and whether the acute renal failure was a specific or unspecific consequence of Plasmodium falciparum infection. This review attempts to answer questions about “chronic quartan malaria nephropathy” and “acute falciparum malaria nephropathy”. The literature review was performed on all publications on kidney involvement in human and experimental malarial infections accessible in PubMed or available at the library of the London School of Hygiene and Tropical Medicine. The association of a nephrotic syndrome with quartan malaria was mostly described before 1975 in children and rarely in adult patients living in areas endemic for Plasmodium malariae. The pooled data on malaria-induced acute renal failure included children and adults acquiring falciparum malaria in endemic areas either as natives or as travellers from non-tropical countries. Non-immunes (not living in endemic areas) had a higher risk of developing acute renal failure than semi-immunes (living in endemic areas). Children with cerebral malaria had a higher rate and more severe course of acute renal failure than children with mild malaria. Today, there is no evidence of a dominant role of steroid-resistant and chronic “malarial glomerulopathies” in children with a nephrotic syndrome in Africa. Acute renal failure was a frequent and serious complication of falciparum malaria in non-immune adults. However, recently it has been reported more often in semi-immune African children with associated morbidity and mortality.  相似文献   
993.
A 57-year-old woman was hospitalized with a left renal artery aneurysm (RAA). The aneurysm measured 35 mm in diameter and was located at the renal artery bifurcation. We performed a laparoscopic nephrectomy using a retroperitoneal approach and performed an ex vivo repair of the renal artery. The reconstructed kidney was then autotransplanted at the left iliac fossa. The patient's postoperative course was uneventful. A laparoscopic nephrectomy and ex vivo repair are both considered to be effective for treating complex RAA.  相似文献   
994.
Purpose In this randomized, double-blind study, we aimed to compare the effectiveness of lornoxicam and ondansetron for the prevention of intrathecal fentanyl-induced pruritus in patients undergoing cesarean section. Methods One hundred and eight parturients (American Society of Anesthesiologists [ASA] I-II status) requesting neuraxial analgesia by a combined spinal-epidural (CSE) technique were recruited for this study. A CSE technique was performed and anesthesia was achieved with fentanyl 25 μg and hyperbaric bupivacaine 12 mg. Patients were randomly allocated to three groups, each with 36 participants. Immediately following delivery, patients received either lornoxicam 8 mg IV (group L; n = 36), ondansetron 8 mg IV (group O; n = 36), or normal saline 2 ml IV (group P; n = 36). Pruritus, pain, and nausea and vomiting scores were recorded during the initial 24 h postoperatively. Results The incidence of pruritus was significantly lower in group O from 4 to 12 h postoperatively when compared to that in group L and group P. According to the pruritus grading system we used, the number of patients without pruritus was significantly higher in group O when compared to that in group L and group P. The number of patients experiencing moderate pruritus was significantly lower in group O when compared to that in group P. Conclusion We observed that the administration of 8 mg IV lornoxicam failed to prevent intrathecal fentanyl-induced pruritus in parturients. Also, our data confirmed that ondansetron is likely to attenuate intrathecal fentanyl-induced pruritus.  相似文献   
995.
The nasolabial fold is a significant facial landmark. Its size, shape, and symmetry are important in facial reanimation surgery, while effacement is an important goal in rejuvenation surgery. However, quantitative data for the nasolabial fold volume (NLFV) and depth is still unavailable. We present a new method of measurement using 3D color speckle stereophotogrammetry and its application in the assessment of NLFV. The VECTRA-3D system was validated to determine its minimum resolution and accuracy. Normal volunteers aged 13–84 years (n = 87) were imaged in repose. Mother–daughter pairs (n = 15, aged 13–61) were imaged in the upright and supine positions. All data were processed using custom software and analyzed by linear regression and nonparametric tests as appropriate. NLFV varied from 0.0026 to 0.2306 ml. There was significant correlation between NLFV and age (r = 0.7269, p < 0.0001). Men had significantly higher NLFV than women across all ages. There was no significant difference between the left and right NLFV. NLFV altered significantly from upright to supine in all subjects (p = 0.0012). However, the mothers increased their NLFV by 32% from supine to upright postures, which was a greater change than observed in their daughters. We have demonstrated a rapid, objective, and non-invasive assessment tool for facial reanimation and rejuvenation surgery. We have quantified the effects of age and posture on NLFV, and the efficacy and longevity of rejuvenation procedures are currently under investigation.  相似文献   
996.
Opinions differ as to the exact mechanism responsible for spondylolysis (SP) and whether individuals with specific morphological characteristics of the lumbar vertebral neural arch are predisposed to SP. The aim of our study was to reveal the association between SP and the architecture of lumbar articular facets and the inter-facet region. Methods: Using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA, USA), length, width and depth of all articular facets and all inter-facet distances in the lumbar spine (L1–L5) were measured. From the Hamann-Todd Human Osteological Collection (Cleveland Museum of Natural History, OH, USA) 120 normal male skeletons with lumbar spines in the control group and 115 with bilateral SP at L5 were selected. Analysis of variance was employed to examine the differences between spondylolytic and normal spines. Results: Three profound differences between SP and the norm appeared: (1) in individuals with SP, the size and shape of L4’s neural arch had significantly greater inter-facet widths, significantly shorter inter-facet heights and significantly shorter and narrower articular facets; (2) only in the L4 vertebra in individuals with SP was the inferior inter-facet width greater in size than the superior inter-facet width of the vertebra below (L5) (38.7 mm versus 40 mm); (3) in all lumbar vertebrae, the right inferior articular facets in individuals with SP were flatter compared to the control group. Conclusions: Individuals with L4 “SP” characteristics are at a greater risk of developing fatigue fractures in the form of spondylolysis at L5.  相似文献   
997.
A soleus flap as a local reconstructive option for soft-tissue coverage of a tibial wound in the distal third of the leg has never been well recognized. In a 2-year period, seven patients underwent reconstruction of a less extensive tibial wound (4 × 3 to 10 × 4 cm) in the distal third of the leg after orthopedic trauma with the laterally extended medial hemisoleus flap. The flap was elevated with emphasis on the preservation of the most distal perforators from the posterior tibial vessels to the flap as possible while allowing adequate rotation of the flap to cover the exposed tibia and/or hardware and on the possible preservation of foot planter flexion by reconstruction of the proximal Achilles’ tendon. In this series, there was no total or partial flap loss. All patients healed their tibial wounds primarily with reliable soft-tissue coverage, evidenced fracture healing, and good cosmetic outcome during follow-up. Thus, the laterally extended medial hemisoleus flap described by the author can be a reliable option for soft-tissue coverage of a less extensive tibial wound in the distal third of the leg. It offers a more cost-effective approach for managing this unique problem and can be performed by most reconstructive surgeons without microsurgical expertise.  相似文献   
998.
Objective A national survey was conducted among the urologists in India to find the preference for urinary diversion after radical cystectomy for muscle invasive carcinoma of the urinary bladder, percentage of neobladder reconstruction, segment of the bowel used, complication rate, need for self-intermittent catherisation on follow up and the survival. Material and methods A detailed questionnaire was mailed to all members of the urological society of India (USI) to find out their preference for urinary diversion following radical cystectomy for muscle invasive carcinoma urinary bladder. For the neobladder reconstruction, they were asked for the type of bowel segment used, complication rate, reoperation rate, need for intermittent clean catheterisation on follow up and 5-year survival. Results A total of 24 institutions responded to the mailed questionnaire. Of all institutions 12 (50%) did not prefer the orthotopic neobladder (ONB) reconstruction. Among the institutions carrying out neobladder reconstruction, majority perform ileal conduit in more than 50% of the cases. Ileum (66.66%) or ileocaecal (16.66%) segment was the choice of bowel segment for most of the urologists. Only three institutions used sigmoid colon. The complications encountered were wound infection (5–25%), burst abdomen (5%), urinary fistulas (3–25%), faecal fistulas (2–5%), bladder neck stenosis (5–15%) and ureterointestinal anastomosis stenosis (5–25%). The reoperation rate was 5–15% with a perioperative mortality of 0.5–3%. Around 10–100% (average 50%) of the patients require intermittent clean catherisation. Only seven institutions could provide 5-year survival rate data. Of these three institutions reported more than 50% and four institutes less than 50% 5-year survival. Conclusion Ileal conduit still remains the urinary diversion of choice following radical cystectomy for muscle invasive carcinoma of the bladder among most of the urologists in India. Orthotopic neobladder reconstruction is practiced only in selected centres. Wound infection, urinary leak and obstruction at ureterointestinal anastomosis are the main complications. Clean intermittent cathaterisation is required at an average of 50% of the patients to ensure complete emptying of the neobladder.  相似文献   
999.
Intestinal denervation contributes to enteric motor dysfunction after small bowel transplantation (SBT). Our aim was to determine long-term effects of extrinsic denervation on function of nonadrenergic, noncholinergic innervation with substance P and vasoactive intestinal polypeptide (VIP). Contractile activity of jejunal circular muscle strips from six age-matched, naive control rats (NC) and eight rats 1 year after syngeneic SBT was studied in tissue chambers. Spontaneous contractile activity did not differ between groups. Exogenous VIP inhibited contractile activity dose-dependently to a comparable degree in both groups. The VIP antagonist ([d-p-Cl-Phe6,Leu17]-VIP) and the nitric oxide synthase inhibitor l-NG-nitro-arginine did not affect VIP-induced inhibition but increased contractile activity during electrical field stimulation (EFS) in both groups. Exogenous substance P increased contractile activity dose-dependently, greater in NC than SBT. The substance P antagonist ([d-Pro2,d-Trp7,9]-substance P) inhibited effects of exogenous substance P and decreased the excitatory EFS response. Immunohistofluorescence showed tyrosine hydroxylase staining after SBT indicating sympathetic reinnervation. In jejunal circular muscle after chronic denervation, response to exogenous substance P, but not VIP, is decreased, whereas endogenous release of both neurotransmitters is preserved. Alterations in balance of excitatory and inhibitory pathways occur despite extrinsic reinnervation and might contribute to enteric motor dysfunction after SBT. Parts of this work were presented at the annual meeting of the Society for Surgery of the Alimentary Tract in Washington, DC, on May 21, 2007 and published in abstract form in Gastroenterology 2007;132:A890.  相似文献   
1000.
Nowadays the vascularized free fibula flap and the free iliac crest flap are the methods most frequently used to reconstruct the mandible. This is also the case in our clinic. A retrospective nonrandomized study was performed to compare both flaps. The vascularized fibula free flap and the iliac crest free flap were compared in terms of logistics, flap failure, revisionary surgery, donor site morbidity, and recipient site morbidity. No significant differences in flap failure and revision surgery were found between the fibula group and the iliac crest group. Recipient site and donor site complications (major and minor) were significantly less in the fibula group compared to the iliac crest group. In mandibular reconstruction, the free vascularized fibula flap appears to be superior to the free vascularized iliac crest flap in terms of both recipient site and donor site morbidity.  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