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   4397篇
  免费   431篇
  国内免费   66篇
耳鼻咽喉   20篇
儿科学   223篇
妇产科学   131篇
基础医学   208篇
口腔科学   168篇
临床医学   594篇
内科学   1175篇
皮肤病学   38篇
神经病学   130篇
特种医学   155篇
外科学   776篇
综合类   225篇
现状与发展   1篇
一般理论   1篇
预防医学   406篇
眼科学   43篇
药学   295篇
中国医学   16篇
肿瘤学   289篇
  2024年   14篇
  2023年   134篇
  2022年   165篇
  2021年   215篇
  2020年   196篇
  2019年   232篇
  2018年   238篇
  2017年   202篇
  2016年   204篇
  2015年   177篇
  2014年   253篇
  2013年   425篇
  2012年   208篇
  2011年   221篇
  2010年   192篇
  2009年   194篇
  2008年   168篇
  2007年   169篇
  2006年   163篇
  2005年   132篇
  2004年   119篇
  2003年   102篇
  2002年   85篇
  2001年   79篇
  2000年   59篇
  1999年   43篇
  1998年   46篇
  1997年   47篇
  1996年   36篇
  1995年   34篇
  1994年   34篇
  1993年   23篇
  1992年   32篇
  1991年   22篇
  1990年   21篇
  1989年   17篇
  1988年   23篇
  1987年   24篇
  1986年   21篇
  1985年   18篇
  1984年   26篇
  1983年   16篇
  1982年   6篇
  1981年   18篇
  1980年   8篇
  1979年   9篇
  1978年   8篇
  1977年   4篇
  1976年   6篇
  1973年   2篇
排序方式: 共有4894条查询结果,搜索用时 22 毫秒
31.
目的探讨抗生素不同用药方案对乳癌术后手术部位感染的预防效果和成本的影响。方法506例乳腺癌改良根治手术患者随机分为观察组(n=253)和对照组(n=253)。观察组术前半小时静脉滴注头孢曲松2.0g;对照组术后3d每天静脉滴注头孢曲松2.0g。观察和记录术后患者手术部位感染情况并计算感染有关的医疗成本。结果术后感染发生率观察组和对照组分别为1.19%(3/252)和1.58%(4/253),其中手术部位感染共6例(1.19%),观察组和对照组各3例(1.19%),差异无统计学意义(P>0.05);对照组呼吸道感染1例。预防和治疗术后感染的直接医疗费用观察组为(163±78)元,对照组为(388±134)元,差异有统计学意义(P<0.05)。结论成本-效果分析表明,术前单次头孢曲松在预防手术部位感染方面与对照组等效,且医疗费用显著降低,具有更高的性价比。  相似文献   
32.
Phenotypically, ganciclovir-resistant human cytomegalovirus strains could be selected by aciclovir as effectively as by ganciclovir in vitro. Three clinical human cytomegalovirus isolates with different sensitivities against ganciclovir, aciclovir, foscarnet, and cidofovir, but without any mutation in the viral UL97 protein known to confer ganciclovir resistance, were propagated each in duplicate in the presence of ganciclovir or aciclovir. After drug selection, all 12 strains were less susceptible to ganciclovir (increase of 50% focus reduction dose between 2.1- and 31.5-fold) but were still sensitive to foscarnet and cidofovir; 7/12 exhibited a ganciclovir-resistant phenotype with a 50% focus reduction dose >30 microM, and in 6 out of these typical mutations in the UL97 coding region could be found by genotyping. All four strains selected from one isolate carried the identical UL97 mutation at amino acid position 460 (methionine to valine). The decreased sensitivity to ganciclovir and aciclovir in the other strains could neither be attributed to known UL97 mutations nor to mutations in the viral polymerase (UL54), which have been reported to induce resistance.  相似文献   
33.

Background

Group B Streptococcus (GBS) infection is one of the major causes of neonatal morbidity and mortality. Universal GBS screening with intrapartum antibiotic prophylaxis (IAP) in pregnant women were initiated in 2012 in Taiwan. This study aimed to analyze the most recent maternal GBS colonization rate and the changes in neonatal GBS infection rate from 2011 to 2016.

Methods

All pregnant women and their live born neonates between January 2011 and June 2016 were retrospectively reviewed. Whether GBS screening was done, screening results, presence of risk factors, the use of antibiotics, and neonatal outcome were analyzed. In addition, hospitalized neonates diagnosed with GBS infections were retrieved for comparison of early onset disease (EOD) (<7 days) and late onset disease (LOD) (≥7 days).

Results

A total of 9535 women delivered babies during the study period. The maternal GBS screening rate was 71.0% and the colonization rate was 22.6%. The overall neonatal invasive GBS infection rate was 0.81 per 1000 live births and the vertical transmission rate was 1.2%. After 2012, the invasive neonatal GBS infection rate declined from 1.1–1.6‰ to 0.6–0.7‰ in 2014 and thereafter, the GBS EOD incidence rate declined from 2.8‰ to 0.0–0.6‰, but the LOD incidence rate remained approximately 0.7‰. Infants with EOD had strong association with obstetric risk factors.

Conclusions

Taiwan's universal GBS screening with IAP program reduced the incidence rate of neonatal GBS EOD to be lower than 1‰ after 2012. Pediatricians still should pay attention to infants with GBS LOD since its incidence rate remained unchanged.  相似文献   
34.
Zusammenfassung Eine perioperative antibiotische Kurzprophylaxe mit 2 g Cefamandol intravenös bei Narkoseeinleitung wurde bei 12 Patienten während coronarchirurgischer Eingriffe unter Verwendung der Herz-Lungen-Maschine durchgeführt. Bei Beginn der extrakorporalen Zirkulation (= EKZ) kam es infolge Hämodilution zu einem Absinken der Serumkonzentrationen von 110,96 ± 40,29 mcg/ml auf 70,89 ± 34,65 g/ml innerhalb von 10 min. Im weiteren Verlauf der EKZ war der Abfall der Serumspiegel gleich schnell wie davor und danach. Nach 240 min fanden sich noch Serumspiegel von 16,80 ± 9,32 g/ml. Als Ursache für das Versagen einer antibiotischen Prophylaxe kommt bei einer Operationsdauer von mehr als 4 h das Absinken der Serumspiegel unter die minimale Hemmkonzentration der entsprechenden Keime in Frage.
Perioperative cefamandole prophylaxis in aortocoronary bypass operations: Course of serum concentration during extracorporeal circulation
Summary Antibiotic prophylaxis with 2 g Cefamandole at induction of anaesthesia was performed in 12 male patients undergoing aortocoronary bypass surgery. Caused by hemodilution, there was a marked decrease of serum concentration at the beginning of extracorporeal circulation, from 110.96 ± 40.29 mcg/ml to 70.89 ± 34.65 mcg/ml within 10 min. During extracorporeal circulation, elimination was as fast as before and after perfusion. 240 min after application, mean serum concentrations of 16.80 ± 9.32 mcg/ml were measured. Failure of antibiotic prophylaxis in operations exceeding 4 h might be due to unadaequate antibiotic concentrations, beyond the minimal inhibitory concentration for the pathogens, reported to cause infections after cardiac operations.
  相似文献   
35.
In Karachi, Pakistan, a South Asian megacity with a high prevalence of tuberculosis (TB) and low HIV prevalence, we assessed the effectiveness of fluoroquinolone-based preventive therapy for drug-resistant (DR) TB exposure. During February 2016–March 2017, high-risk household contacts of DR TB patients began a 6-month course of preventive therapy with a fluoroquinolone-based, 2-drug regimen. We assessed effectiveness in this cohort by comparing the rate and risk for TB disease over 2 years to the rates and risks reported in the literature. Of 172 participants, TB occurred in 2 persons over 336 person-years of observation. TB disease incidence rate observed in the cohort was 6.0/1,000 person-years. The incidence rate ratio ranged from 0.29 (95% CI 0.04–1.3) to 0.50 (95% CI 0.06–2.8), with a pooled estimate of 0.35 (95% CI 0.14–0.87). Overall, fluoroquinolone-based preventive therapy for DR TB exposure reduced risk for TB disease by 65%.  相似文献   
36.
IntroductionSleeve gastrectomy has currently become the most commonly performed bariatric. procedure worldwide according to the last IFSO survey, overtaking gastric bypass with. a share of more than 50% of all primary bariatric-metabolic surgery. Gastric leak, intraluminal bleeding, bleeding from the staple-line and strictures are the most common complications. Portomesenteric vein thrombosis (PMVT)after sleeve gastrectomy is. another complication that has been increasingly reported in case-series in recent.years, although it remains uncommon. In this case report is described an extended portomesenteric vein thrombosis after. sleeve gastrectomy interesting splenic vein too with a favorable course and an. uneventful follow-up. We try to search in this case for pathogenetic factors involved in. this complication.Case reportA 42-year old man, with a body mass index (BMI) of 45 kg/m2, with a medical history of Obstructive Sleep Apnea Sindrome (OSAS) underwent laparoscopic sleeve gastrectomy. Early postoperative course was uneventful. Six days after discharge he complained abdominal pain and was admitted at the Emergency Department. A CT scan with intravenous contrast showed an occlusion of the portal vein, of the intrahepatic major branches and an extension to the superior mesenteric vein and the splenic vein. The patient received heparin and oral anticoagulation together with intravenous hydration and proton pump inhibitors. Considering the favourable course the patient was discharged after six days with long-term oral anticoagulation therapy. Anticoagulation with acenocumarol was continued for six months after a CT scan showed resolution of the PMVT without cavernoma. He had no recurrence of symptoms.DiscussionPorto-mesenteric thrombosis after sleeve gastrectomy is a rare complication but it has been increasingly reported over the last 10 years along with the extensive use of sleeve gastrectomy. Because PMVT is closely associated with sleeve gastrectomy in comparison with other bariatric procedures, we need to investigate what pathogenetic factors are involved in sleeve gastrectomy. Thrombophylic state, prolonged duration of surgery, high levels of pneumoperitoneum, thermal injury of the gastroepiploic vessels during greater curvature dissection, high intragastric pressure, inadequate antithrombotic prophylaxis and delayed mobilization of the patient after surgery have been reported as pathogenetic factors of portmesenteric vein thrombosis. Most of the cases presented in the literature such as our clinical case resolve with medical therapy, although portal vein thrombus extends into the superior mesenteric vein and the splenic vein.ConclusionPortomesenteric venous thrombosis is a rare but serious complication of bariatric surgery, especially associated with sleeve gastrectomy. Diagnosis is based on CT examination with intravenous contrast, and initial therapy is anticoagulation. Etiologic factors reported in the literature include a long duration of surgery, a high degree of pneumoperitoneum, high intragastric pressure after sleeve gastrectomy and thermal injury to the short gastric vessels and gastroepiploic arcade. Limited operative time, controlled values of pneumoperitoneum, careful dissection with energy device of gastric greater curvature, appropriate prophylaxis with low molecular weight heparin may be useful tools to prevent and limit this complication. Nonetheless we have to search which factors may condition the evolution of an extended PMVT as that described in this case towards resolution or to a further worsening clinical state. Early diagnosis? Correct treatment? Undiscovered patientrelated factors?  相似文献   
37.
BackgroundVancomycin powder and dilute povidone-iodine lavage (VIP) was introduced to reduce the incidence of periprosthetic joint infection (PJI) in high-risk total knee arthroplasty (TKA) patients. We hypothesize that VIP can reduce the incidence of early PJI in all primary TKA patients, regardless of preoperative risk.MethodsAn infection database of primary TKAs performed before a VIP protocol was implemented (January 2012-December 2013), during a time when only high-risk TKAs received VIP (January 2014-December 2015), and when all TKAs received VIP (January 2016-September 2019) at an urban, university-affiliated, not-for-profit orthopedic hospital was retrospectively reviewed to identify patients with PJI. Criteria used for diagnosis of PJI were the National Healthcare Safety Network and Musculoskeletal Infection Society guidelines.ResultsVIP reduced early primary TKA PJI incidence in both the high-risk and all-risk cohorts compared with the pre-VIP cohort by 44.6% and 56.4%, respectively (1.01% vs 0.56% vs 0.44%, P = .0088). In addition, after introducing VIP to all-risk TKA patients, compared with high-risk TKA patients, the relative risk of PJI dropped an additional 21.4%, but this finding did not reach statistical significance (0.56% vs 0.44%, P = .4212). There were no demographic differences between the 3 VIP PJI cohorts.ConclusionVIP is associated with a reduced early PJI incidence after primary TKA, regardless of preoperative risk. With the literature supporting its safety and cost-effectiveness, VIP is a value-based intervention, but given the nature of this historical cohort study, a multicenter randomized controlled trial is underway to definitively confirm its efficacy.  相似文献   
38.
Antibiotic prophylaxis in surgery is one of the most effective measures for preventing surgical site infection, although its use is frequently inadequate and may even increase the risk of infection, toxicities and antimicrobial resistance. As a result of advances in surgical techniques and the emergence of multidrug-resistant organisms, the current guidelines for prophylaxis need to be revised.The Sociedad Española de Enfermedades Infecciosas (Spanish Society of Infectious Diseases and Clinical Microbiology) (SEIMC) together with the Asociación Española de Cirujanos (Spanish Association of Surgeons) (AEC) have revised and updated the recommendations for antibiotic prophylaxis in surgery to adapt them to any type of surgical intervention and to current epidemiology. This document gathers together the recommendations on antimicrobial prophylaxis in the various procedures, with doses, duration, prophylaxis in special patient groups, and in epidemiological settings of multidrug resistance to facilitate standardized management and the safe, effective and rational use of antibiotics in elective surgery.  相似文献   
39.
40.
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