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   3792篇
  免费   227篇
  国内免费   22篇
耳鼻咽喉   53篇
儿科学   118篇
妇产科学   143篇
基础医学   413篇
口腔科学   64篇
临床医学   264篇
内科学   711篇
皮肤病学   80篇
神经病学   249篇
特种医学   117篇
外国民族医学   2篇
外科学   720篇
综合类   171篇
预防医学   212篇
眼科学   112篇
药学   370篇
中国医学   33篇
肿瘤学   209篇
  2023年   32篇
  2022年   97篇
  2021年   145篇
  2020年   68篇
  2019年   107篇
  2018年   136篇
  2017年   94篇
  2016年   93篇
  2015年   85篇
  2014年   154篇
  2013年   160篇
  2012年   244篇
  2011年   270篇
  2010年   160篇
  2009年   117篇
  2008年   209篇
  2007年   212篇
  2006年   181篇
  2005年   186篇
  2004年   126篇
  2003年   132篇
  2002年   104篇
  2001年   67篇
  2000年   70篇
  1999年   80篇
  1998年   39篇
  1997年   24篇
  1996年   25篇
  1995年   20篇
  1994年   20篇
  1992年   43篇
  1991年   44篇
  1990年   52篇
  1989年   39篇
  1988年   31篇
  1987年   18篇
  1986年   26篇
  1985年   28篇
  1984年   16篇
  1981年   16篇
  1980年   12篇
  1979年   27篇
  1978年   15篇
  1977年   12篇
  1976年   25篇
  1975年   16篇
  1974年   26篇
  1973年   19篇
  1972年   11篇
  1971年   15篇
排序方式: 共有4041条查询结果,搜索用时 15 毫秒
51.
Management of the third stage of labor in an Egyptian teaching hospital.   总被引:2,自引:0,他引:2  
OBJECTIVES: The study describes normal labor practices in an Egyptian teaching hospital for the first time, where postpartum hemorrhage is the leading cause of maternal mortality. Third-stage management patterns are described and compared to evidence-based medicine. Reasons for third-stage practices observed are explored. STUDY DESIGN: 176 normal births were directly observed. Women were interviewed postpartum and study findings were shared with providers. RESULTS: Third-stage active management was correctly done for 15% of women observed. Most common deviations for the remaining 85% were: giving uterotonic drugs after placental delivery (65%) and without cord traction (49%). Passive management was not done for any observed delivery. CONCLUSIONS: The preventive role actively managing the third stage can provide against postpartum hemorrhage was lost to the majority of the deliveries observed. Obstacles to adopting protocols shown to reduce hemorrhage should be explored, given the contribution of postpartum hemorrhage to maternal deaths in Egypt.  相似文献   
52.
We reviewed the literature for different diagnostic approaches for dry eye disease (DED) including the most recent advances, contradictions and promising diagnostic tools and technique. We performed a broad literature search for articles discussing different methods for diagnosis of DED including assessment of tear osmolarity, tear film stability, ocular biomarkers and others. Articles indexed in PubMed and google scholar were included. With the growing cosmetic industry, environmental pollution, and booming of digital screens, DED is becoming more prevalent. Its multifactorial etiology renders the diagnosis challenging and invites the emergence of new diagnostic tools and tests. Diagnostic tools can be classified, based on the parameter they measure, into tear film osmolarity, functional visual acuity, tear volume, tear turnover, tear film stability, tear film composition, ocular biomarkers and others. Although numerous methods exist, the most accurate diagnosis can be reached through combining the results of more than one test. Many reported tests have shown potential as diagnostic/screening tools, however, require more research to prove their diagnostic power, alone or in combination. Future research should focus on identifying and measuring parameters that are the most specific to DED diagnosis.  相似文献   
53.
T-cell-derived antigen-binding molecules (TABMs) specific for benzoic acid were isolated from the serum of a toluene-sensitive patient. The resulting purified TABMs (BA-TABMs) did not contain immunoglobulin G and were associated with the cytokine transforming growth factor-β (TGF-β). BA-TABMs bound to benzoic acid conjugated to human serum albumin (BA-HSA), as well as to other chemicals conjugated to human serum albumin—including dinitrophenol and oxazolone. The binding of BA-TABMs to the conjugated chemicals increased the level of detectable TGF-β, and a similar effect was observed with the unconjugated chemicals, benzoic acid and 2,4-dinitrophenol glycine. The increase in TGF-β was critically dependent on the ratio between BA-TABMs and the conjugated or unconjugated chemicals; the increase was optimum at intermediate concentrations and absent at low and high concentrations. The authors used an established animal model in vivo and demonstrated that TGF-β enhanced the inflammatory response induced by the release of neuropeptides from sensory nerves; this enhancement occurred in a dose-dependent manner. The BA-TABMs also enhanced this neurogenic inflammatory response in a dose-dependent manner, and this effect was blocked by anti-TGF-β antibody. When the authors added either BA-HSA or benzoic acid, the effect of BA-TABMs on neurogenic inflammation was further enhanced at intermediate concentrations of antigen and was unaltered or reduced at higher concentrations. TABMs specific to particular chemicals, as a result of their association with cytokines (e.g., TGF-β), may be implicated in symptom production in chemically sensitive patients.  相似文献   
54.
Healthcare professional schools across the world are implementing near‐peer tutoring (NPT) programs owing to numerous benefits to both tutors and tutees. This study determined whether higher attendance at NPT sessions led to improvements in course grades for high and low performing students. Fourth‐year medical students used the USMLE Step 1 question format to tutor first‐year medical students during the second half of the Structure and Function (SF) module, i.e., SF2. Attendance was recorded and students were accordingly divided into three groups: high, moderate, and low‐no attendance. Students’ performances in SF1 and SF2 were compared using Student's t‐test. Differences among the three groups were analyzed using ANOVA and Scheffé post hoc test (P< 0.05). Students who earned 70–79% (C) in SF1 were further examined on the basis of their attendance rate and performance in SF2. Those who attended three or more sessions completed a survey evaluating the NPT program. Course grades were significantly higher in SF2 than SF1 for all students, regardless of attendance rate. However, students who received a C grade in SF1 and had high or moderate attendance improved significantly in their SF2 course grade. Most students agreed that the NPT program was valuable and they evaluated the tutors highly. They also agreed that NPT prepared them for course exams and Step 1, but did not reduce anxiety and stress about Step 1. The positive effect of the NPT program resulted in its expansion to include all first‐year modules. Clin. Anat. 30:922–928, 2017. © 2017 Wiley Periodicals, Inc.  相似文献   
55.
56.
57.
Enteroaggregative Escherichia coli (EAEC) are a leading cause of diarrhea among children. The objective of this study was to define the frequency of EAEC among diarrheal children from flood‐affected areas as well as sporadic cases, determine multidrug resistance, and evaluation of virulence using an in vivo model of pathogenesis. Stool samples were collected from 225 diarrheal children from 2010 to 2011 from flood‐affected areas as well as from sporadic cases in Pakistan. Identified EAEC isolates were characterized by phylogrouping, antibiotic resistance patterns including the extended‐spectrum beta lactamase spectrum, single nucleotide polymorphism detection in gyrA and parC, and virulence potential using wax worm, G. mellonella. A total of 35 (12.5%) confirmed EAEC isolates were identified among 225 E. coli isolates. EAEC isolates displayed high resistance to tetracycline, ampicillin, and cefaclor. A total of 34.28% were ESBL positive. Single nucleotide polymorphism detection revealed 37.14% and 68.57% isolates were positive for SNPs in gyrA (A660‐T660) and parC (C330‐T330), respectively. Phylogrouping revealed that B2 phylogroup was more prevalent among all EAEC isolates tested followed by D, A, B1, and non‐typeable (NT). Infection of G. mellonella with EAEC showed that killing infective dose was 100% higher than E. coli DH5 alpha control. EAEC are prevalent among Pakistani children with diarrhea, they are highly resistant to antibiotics, and predominantly fall into B2 phylogroup. Epidemiologic surveillance of EAEC and other E. coli pathotypes is critical to assess not only the role of these pathogens in diarrheal disease but also to determine the extent of multidrug resistance among the population.  相似文献   
58.
In Morocco, Alzheimer's disease (AD) affects almost 30,000 individuals, and this number could increase to 75,000 by 2020. To our knowledge, the genes predisposing individuals to AD and predicting disease incidence remain elusive. In this study, we aimed to evaluate the genetic contribution of mutations in the amyloid precursor protein (APP) gene exons 16 and 17 to familial and sporadic AD cases. Seventeen sporadic cases and eight family cases were seen at the memory clinic of the University of Casablanca Neurology Department. These patients underwent standard somatic neurological examination, cognitive function assessment, brain imaging, and laboratory tests. Direct sequencing of exons 16 and 17 of the APP gene was performed on genomic DNA of AD patients. In this original Moroccan study, we identified seven novel frameshift mutations in exons 16 and 17 of the APP gene. Interestingly, only one novel splice mutation was detected in a family case. There is a strong correlation between clinical symptoms and genetic factors in Moroccan patients with a family history of AD. Therefore, mutations in APP gene exons 16 and 17 may eventually become genetic markers for AD predisposition.  相似文献   
59.
60.
IntroductionPeriodontal mechanoreceptors (PMRs) are refined neural receptors present in abundance at the root apex and have a pivotal role in oral fine motor control. This case-control study aimed to evaluate the oral fine motor control of teeth treated with endodontic microsurgery (EMS) in comparison with the control teeth using a standardized behavioral biting task.MethodsFourteen eligible participants performed 5 trials of an oral fine motor control task that involved holding and splitting half of a peanut positioned on a force transducer with their EMS treated tooth and its contralateral control incisor tooth (28 teeth in total). The outcome variables were the mean food holding force, intra- and intertrial variability of the holding force, food splitting force, splitting duration, and the frequency of the stepwise splitting phase. The data were analyzed with parametric and nonparametric tests.ResultsThe results showed no statistically significant differences in the holding force, inter- and intratrial variability of the holding force, splitting force, or splitting duration between the teeth treated with EMS and the control (P > .05). However, there was a significantly higher frequency of stepwise ramp increase during the splitting phase with EMS treated teeth compared with the control (48% and 37%, respectively; P < .05).ConclusionsEMS treated teeth showed similar force regulation and oral fine motor control as the contralateral control. The findings of this study suggest that EMS treatment does not perturb the sensory information of PMRs and maintains the force regulation and oral fine motor control of the teeth.  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