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   15817篇
  免费   1125篇
  国内免费   72篇
耳鼻咽喉   265篇
儿科学   611篇
妇产科学   450篇
基础医学   1922篇
口腔科学   251篇
临床医学   1626篇
内科学   3565篇
皮肤病学   492篇
神经病学   1296篇
特种医学   530篇
外科学   2539篇
综合类   195篇
一般理论   20篇
预防医学   1001篇
眼科学   347篇
药学   966篇
中国医学   33篇
肿瘤学   905篇
  2023年   123篇
  2022年   227篇
  2021年   591篇
  2020年   344篇
  2019年   456篇
  2018年   525篇
  2017年   382篇
  2016年   430篇
  2015年   421篇
  2014年   561篇
  2013年   754篇
  2012年   1064篇
  2011年   1089篇
  2010年   588篇
  2009年   559篇
  2008年   842篇
  2007年   930篇
  2006年   844篇
  2005年   796篇
  2004年   746篇
  2003年   634篇
  2002年   547篇
  2001年   231篇
  2000年   203篇
  1999年   208篇
  1998年   147篇
  1997年   97篇
  1996年   88篇
  1995年   71篇
  1994年   76篇
  1993年   78篇
  1992年   123篇
  1991年   132篇
  1990年   115篇
  1989年   121篇
  1988年   109篇
  1987年   110篇
  1986年   118篇
  1985年   116篇
  1984年   102篇
  1983年   85篇
  1982年   83篇
  1981年   103篇
  1980年   71篇
  1979年   85篇
  1978年   75篇
  1977年   66篇
  1975年   46篇
  1974年   52篇
  1972年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Summary In 14 closed-chest dogs, the significance of right ventricular filling for left ventricular enddiastolic pressure-volume relationship was investigated under acute hypoxia by means of single plane cineventriculography and simultaneous intraventricular pressure recording.Both after 5 min asphyxia (respirator switched off) (n=5) and after 3 min hypoxia (ventilation with pure N2) (n=9), there was a significant leftward shift (p<0.005) of the left ventricular enddiastolic pressure-volume curve as compared to the control curves under normoxia. To simulate the elevated filling of the right ventricle under acute hypoxia, rapid intraventricular infusion was applier under normoxic conditions to raise right ventricular enddiastolic pressure to the same values as that measured under hypoxia. The extent of the ensuing leftward shift of the left ventricular enddiastolic pressurevolume curve was on average 60% of the shift under hypoxia in both sets of experiments. Neither the slope of the relationship between volume stiffness and enddiastolic pressure, nor the relationship between tangent elastic modulus and left ventricular wall stress, was affected by hypoxia or asphyxia.Thus, the shift of the left ventricular enddiastolic pressure-volume curve in the early stage of hypoxia is predominantly due to the influence of increased right ventricular filling. Since the increased volume of the atria under acute hypoxia limits left ventricular distensibility additionally, the changes in left ventricular enddiastolic pressure-volume relationships, observed in the early stage of hypoxia are mainly, or even entircly, the result of interaction of the various heart compartments, and not a reflection of alterations in myocardial tissue elasticity.Preliminary results were presented at the symposium on Cardiac adaptation to hemodynamic overload, training and stress in Tübingen (1983)Supported by the Deutsche Forschungsgemeinschaft  相似文献   
103.
104.
Maternal and Child Health Journal - This study assessed whether the use of a peer-to-peer educational book, written and illustrated by women who experienced common mental disorders (CMDs) in the...  相似文献   
105.
Rosemary extract (RE) is an approved food preservative in the European Union and contains dietary phytochemicals that are beneficial for gastrointestinal health. This study investigated the effects of RE on dextran sodium sulfate (DSS)-induced colitis and also determined the pharmacokinetics of dietary phytochemicals administered to mice via oral gavage. Individual components of rosemary extract were separated and identified by LC–MS/MS. The pharmacokinetics of two major diterpenes from RE, carnosic acid (CA) and carnosol (CL), administered to mice via oral gavage were determined. Then, the effect of RE pre-treatment on the disease activity index (DAI) of DSS-induced colitis in mice was investigated. The study determined that 100 mg/kg RE significantly improved DAI in DSS-induced colitis compared to negative control. Sestrin 2 protein expression, which increased with DSS exposure, was reduced with RE treatment. Intestinal barrier integrity was also shown to improve via fluorescein isothiocyanate (FITC)–dextran administration and Western blot of zonula occludens-1 (ZO-1), a tight junction protein. Rosemary extract was able to improve the DAI of DSS-induced colitis in mice at a daily dose of 100 mg/kg and showed improvement in the intestinal barrier integrity. This study suggests that RE can be an effective preventative agent against IBD.  相似文献   
106.
目的对十年前后精神分裂症患者用药情况的变化进行调查分析.方法对十年前后两个五年段的各500份符合精神分裂症诊断标准的病历进行回顾性调查,并对各项指标进行对比分析.结果两组折算用药剂量经t检验差异无显著性(P>0.05);两组合并用药、合并抗胆碱药及疗效经χ2检验差异有显著性(P<0.01);十年后非典型抗精神病药物氯氮平在临床上的应用比例明显增大并上升为首位.结论十年前后两组抗精神病药的应用发生了明显变化,疗效好、副作用轻的非典型抗精神病药的应用比例明显增加.  相似文献   
107.
BackgroundIn addition to the significant morbidity and mortality associated with periprosthetic joint infection (PJI), the cost of treating PJI is substantial. Prior high-quality national estimates of the economic burden of PJI utilize data up to 2009 to project PJI growth in the United States through 2020. Now in the year 2020, it is appropriate to evaluate these past projections and incorporate the latest available data to better understand the current scale and burden of PJI in the United States.MethodsThe Nationwide Inpatient Sample (2002-2017) was used to identify rates and associated inpatient costs for primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) and PJI-related revision TKA and THA. Poisson regression was utilized to model past growth and project future rates and cost of PJI of the hip and knee.ResultsUsing the most recent data, the combined annual hospital costs related to PJI of the hip and knee were estimated to be $1.85 billion by 2030. This includes $753.4 million for THA PJI and $1.1 billion for TKA PJI, in that year. Increases in PJI costs are mainly attributable to increases in volume. Although the growth in incidence of primary THA and TKA has slowed in recent years, the incidence of PJI and the cost per case of PJI remained relatively constant from 2002 to 2017.DiscussionUnderstanding the current and potential future financial burden of PJI for surgeons, patients, and healthcare systems is essential. There is an urgent need for efficacious preventive strategies in reducing rates of PJI after THA and TKA.  相似文献   
108.
BackgroundProsthetic joint infection (PJI) is the most common cause of failure following total knee arthroplasty (TKA). This study aimed to determine the success of debridement, antibiotics, and implant retention (DAIR) in a large cohort of TKA PJIs and assess the utility of current classification systems in predicting DAIR outcomes in early postoperative, late hematogenous, and chronic PJIs.MethodsIn a multicenter review over 15 years, 230 patients underwent DAIR for first episode PJI following primary TKA. Patient demographics, disease and surgical factors, treatment regime, and outcomes were identified. Univariate and multivariate survival analyses were performed to identify factors associated with successful DAIR. Continuous variables with predictive value were further analyzed using receiver operating characteristic curves. The ability to predict DAIR outcomes of multiple classification systems was also assessed.ResultsPatients were followed for an average of 6.9 years. The overall success rate of DAIR was 53.9%. On receiver operating characteristic analysis, 3 months (area under the curve = 0.63) and 1-year age (area under the curve = 0.66) of implant cut-offs was similarly predictive of outcomes. On multivariate survival analysis, DAIR was successful in 64% of “early” PJIs (implant <1 year) vs 38% of “late hematogenous” PJIs (implant >1 year; odds ratio [OR] 1.78, P = .01). For late PJIs (implant >1 year), Staphylococcus aureus (OR 4.70, P < .001) and gram-negative infections (OR 2.56, P = .031) were risk factors for DAIR failure.ConclusionDAIR has a high failure rate in all PJIs occurring more than a year post primary TKA, particularly when caused by S aureus or gram-negative bacteria. The age of implant is an important predictor of DAIR outcomes.  相似文献   
109.
BackgroundDexamethasone has been shown to reduce postoperative pain and opioid consumption for total joint arthroplasty patients; however, its impact on patients who received neuraxial anesthesia (NA) is not well described. We examined the impact of perioperative dexamethasone on outcomes for patients undergoing direct anterior approach total hip arthroplasty (THA) under NA.MethodsA retrospective review was conducted for 376 THA patients from a single institution. Univariate analysis was used to compare postoperative outcomes for 164 THA patients receiving dexamethasone compared to 212 who did not receive dexamethasone.ResultsNo differences in age, gender, body mass index, or American Society of Anesthesiologists (ASA) Score were observed between the groups. Patients receiving perioperative dexamethasone reported statistically significantly lower postanesthesia care unit (PACU) pain numeric rating scale (Dexamethasone 1.6 vs No dexamethasone 2.3, P = .014) and received lower PACU morphine milligram equivalents (MME) (Dexamethasone 8.57 vs No dexamethasone 11.44, P < .001). Patients receiving dexamethasone had significantly shorter LOS (Dexamethasone 29.40 vs No dexamethasone 35.26 hrs., P < .001).ConclusionPerioperative dexamethasone is associated with decreased postoperative pain and narcotic consumption, and shorter length of stay for patients undergoing primary direct anterior approach THA with NA.  相似文献   
110.
Modifications to the constituents of the gut microbiome influence bone density and tissue-level strength, but the specific microbial components that influence tissue-level strength in bone are not known. Here, we selectively modify constituents of the gut microbiota using narrow-spectrum antibiotics to identify components of the microbiome associated with changes in bone mechanical and material properties. Male C57BL/6J mice (4 weeks) were divided into seven groups (n = 7–10/group) and had taxa within the gut microbiome removed through dosing with: (i) ampicillin; (ii) neomycin; (iii) vancomycin; (iv) metronidazole; (v) a cocktail of all four antibiotics together (with zero-calorie sweetener to ensure intake); (vi) zero-calorie sweetener only; or (vii) no additive (untreated) for 12 weeks. Individual antibiotics remove only some taxa from the gut, while the cocktail of all four removes almost all microbes. After accounting for differences in geometry, whole bone strength was reduced in animals with gut microbiome modified by neomycin (−28%, p = 0.002) and was increased in the group in which the gut microbiome was altered by sweetener alone (+39%, p < 0.001). Analysis of the fecal microbiota detected seven lower-ranked taxa differentially abundant in animals with impaired tissue-level strength and 14 differentially abundant taxa associated with increased tissue-level strength. Histological and serum markers of bone turnover and trabecular bone volume per tissue volume (BV/TV) did not differ among groups. These findings demonstrate that modifications to the taxonomic components of the gut microbiome have the potential to decrease or increase tissue-level strength of bone independent of bone quantity and without noticeable changes in bone turnover. © 2021 American Society for Bone and Mineral Research (ASBMR).  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