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   8530篇
  免费   233篇
  国内免费   21篇
耳鼻咽喉   49篇
儿科学   268篇
妇产科学   175篇
基础医学   1312篇
口腔科学   289篇
临床医学   420篇
内科学   1570篇
皮肤病学   178篇
神经病学   426篇
特种医学   186篇
外科学   997篇
综合类   1100篇
预防医学   924篇
眼科学   108篇
药学   617篇
  1篇
中国医学   58篇
肿瘤学   106篇
  2023年   73篇
  2022年   111篇
  2021年   206篇
  2020年   148篇
  2019年   907篇
  2018年   770篇
  2017年   433篇
  2016年   152篇
  2015年   104篇
  2014年   306篇
  2013年   332篇
  2012年   410篇
  2011年   377篇
  2010年   317篇
  2009年   292篇
  2008年   307篇
  2007年   341篇
  2006年   221篇
  2005年   129篇
  2004年   92篇
  2003年   108篇
  2002年   36篇
  2001年   35篇
  2000年   37篇
  1999年   25篇
  1998年   22篇
  1997年   15篇
  1996年   14篇
  1995年   15篇
  1994年   19篇
  1993年   7篇
  1992年   3篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1986年   1篇
  1985年   172篇
  1984年   297篇
  1983年   224篇
  1982年   248篇
  1981年   236篇
  1980年   208篇
  1979年   209篇
  1978年   159篇
  1977年   121篇
  1976年   159篇
  1975年   143篇
  1974年   128篇
  1973年   104篇
  1972年   1篇
排序方式: 共有8784条查询结果,搜索用时 15 毫秒
1.
《Vaccine》2022,40(7):1001-1009
Vaccination guidelines for dogs and cats indicate that core vaccines (for dogs, rabies, distemper, adenovirus, parvovirus; for cats, feline parvovirus, herpes virus-1, calicivirus) are essential to maintain health, and that non-core vaccines be administered according to a clinician’s assessment of a pet’s risk of exposure and susceptibility to infection. A reliance on individual risk assessment introduces the potential for between-practice inconsistencies in non-core vaccine recommendations. A study was initiated to determine non-core vaccination rates of dogs (Leptospira, Borrelia burgdorferi, Bordetella bronchiseptica, canine influenza virus) and cats (feline leukemia virus) in patients current for core vaccines in veterinary practices across the United States. Transactional data for 5,531,866 dogs (1,670 practices) and 1,914,373 cats (1,661 practices) were retrieved from practice management systems for the period November 1, 2016 through January 1, 2020, deidentified and normalized. Non-core vaccination status was evaluated in 2,798,875 dogs and 788,772 cats that were core-vaccine current. Nationally, median clinic vaccination rates for dogs were highest for leptospirosis (70.5%) and B. bronchiseptica (68.7%), and much lower for canine influenza (4.8%). In Lyme-endemic states, the median clinic borreliosis vaccination rate was 51.8%. Feline leukemia median clinic vaccination rates were low for adult cats (34.6%) and for kittens and 1-year old cats (36.8%). Individual clinic vaccination rates ranged from 0 to 100% for leptospirosis, B. bronchiseptica and feline leukemia, 0–96% for canine influenza, and 0–94% for borreliosis. Wide variation in non-core vaccination rates between clinics in similar geographies indicates that factors other than disease risk are driving the use of non-core vaccines in pet dogs and cats, highlighting a need for veterinary practices to address gaps in patient protection. Failure to implement effective non-core vaccination strategies leaves susceptible dogs and cats unprotected against vaccine-preventable diseases.  相似文献   
2.
BackgroundThe goal of this study was to characterize contemporary performance benchmarks and risk factors associated with negative appendectomy (NA) in children with suspected appendicitis.MethodsA multicenter retrospective cohort analysis of children undergoing appendectomy for suspected appendicitis was performed using data from the 2016–2021 NSQIP-Pediatric Appendectomy Targeted Public Use Files. Multivariable regression was used to evaluate the influence of year, age, sex, and WBC count on NA rate, and to generate rate estimates for NA based on different combinations of demographic characteristics and WBC profiles.Results100,322 patients were included from 140 hospitals. The overall NA rate was 2.4%, and rates decreased significantly during the study period (2016: 3.1% vs. 2021: 2.3%, p < 0.001). In adjusted analyses, the highest risk for NA was associated with a normal WBC (<9000/mm3; OR 5.31 [95% CI: 4.87–5.80]), followed by female sex (OR 1.55 [95% CI: 1.42–1.68]) and age <5 years (OR 1.64 [95% CI 1.39, 1.94]). Model-estimated risk for NA varied significantly across demographic and WBC strata, with a 14.4-fold range in rates between subgroups with the lowest and highest predicted risk (males 13–17 years with elevated WBC [1.1%] vs. females 3–4 years with normal WBC [15.8%]).ConclusionsContemporary NA rates have decreased over time, however NA risk remains high in children without a leukocytosis, particularly for girls and children <5 years of age. These data provide contemporary performance benchmarks for NA in children with suspected appendicitis and identify high-risk populations where further efforts to mitigate NA risk should be targeted.Level of EvidenceIII.  相似文献   
3.
BackgroundRecent guidelines for the treatment of moderate or severe ischemic mitral regurgitation (IMR) in patients undergoing coronary artery bypass grafting (CABG) have changed. This study assessed the real-world impact of changing guidelines on the management of IMR during CABG over time. We hypothesized that the utilization of mitral valve repair for IMR would decrease over time, whereas mitral valve replacement for severe IMR would increase.MethodsPatients undergoing CABG in a statewide collaborative database (2011-2020) were stratified by severity of IMR. Trends in mitral valve repair or replacement were evaluated. To account for differences of the patients, propensity score–matched analyses were used to compare patients with and without mitral intervention.ResultsA total of 11,676 patients met inclusion criteria, including 1355 (11.6%) with moderate IMR and 390 (3.3%) with severe IMR. The proportion of patients undergoing mitral intervention for moderate IMR decreased over time (2011, 17.7%; 2020, 7.5%; Ptrend = .001), whereas mitral replacement for severe IMR remained stable (2011, 11.1%; 2020, 13.3%; Ptrend = .14). Major morbidity was higher for patients with moderate IMR who underwent mitral intervention (29.1% vs 19.9%; P = .005). In a propensity analysis of 249 well-matched pairs, there was no difference in major morbidity (29.3% with mitral intervention vs 23.7% without; P = .16) or operative mortality (1.2% vs 2.4%; P = .5).ConclusionsConsistent with recent guideline updates, patients with moderate IMR were less likely to undergo mitral repair. However, the rate of replacement for severe IMR did not change. Mitral intervention during CABG did not increase operative mortality or morbidity.  相似文献   
4.
5.
ObjectivesTo identify factors associated with 30-day all-cause readmission rates in surgical patients discharged to skilled nursing facilities (SNFs), and derive and validate a risk score.DesignRetrospective cohort.Setting and participantsPatients admitted to 1 tertiary hospital's surgical services between January 1, 2011, and December 31, 2014 and subsequently discharged to 110 SNFs within a 25-mile radius of the hospital. The first 2 years were used for the derivation set and the last 2 for validation.MethodsData were collected on 30-day all cause readmissions, patient demographics, procedure and surgical service, comorbidities, laboratory tests, and prior health care utilization. Multivariate regression was used to identify risk factors for readmission.ResultsDuring the study period, 2405 surgical patients were discharged to 110 SNFs, and 519 (21.6%) of these patients experienced readmission within 30 days. In a multivariable regression model, hospital length of stay [odds ratio (OR) per day: 1.03, 95% confidence interval (CI) 1.02-1.04], number of hospitalizations in past year (OR 1.24 per hospitalization, 95% CI 1.18-1.31), nonelective surgery (OR 1.33, 95% CI 1.18-1.65), low-risk service (orthopedic/spine service) (OR 0.32, 95% CI 0.25-0.42), and intermediate-risk service (cardiothoracic surgery/urology/gynecology/ear, nose, throat) (OR 0.69, 95% CI 0.53-0.88) were associated with all-cause readmissions. The model had a C index of 0.71 in the validation set. Using the following risk score [0.8 × (hospital length of stay) + 7 × (number of hospitalizations in past year) +10 for nonelective surgery, +36 for high-risk surgery, and +20 for intermediate-risk surgery], a score of >40 identified patients at high risk of 30-day readmission (35.8% vs 12.6%, P < .001).Conclusions/ImplicationsAmong surgical patients discharged to an SNF, a simple risk score with 4 parameters can accurately predict the risk of 30-day readmission.  相似文献   
6.
IntroductionThis study aimed to estimate the utility values of all subtypes of lung cancer. The trajectories after different kinds of treatments and their major determinants were explored on the basis of real-world data and repeated measurements.MethodsFrom 2011 to 2017, all patients with lung cancer who visited a medical center were invited to fill out the EuroQol Five-Dimension and WHO Quality of Life-Brief questionnaires at each visit. Utility values of quality of life (QoL) after diagnosis and treatments were depicted using a kernel smoothing method. We constructed linear mixed models to predict health utility in each time period and cross-validated them with domain scores of the WHO Quality of Life-Brief.ResultsA total of 1715 patients were enrolled, with 6762 QoL measurements. Utility values were lower in patients with advanced-stage disease and older patients. Patients receiving second-line targeted therapy showed higher utility values at 0 to 3 months, 3 to 6 months, and 6 months and beyond (0.89, 0.90, and 0.88, respectively) than did those undergoing chemotherapy (0.81, 0.85, and 0.80, respectively). After using mixed models to control confounders, including poor performance status and disease progression, patients receiving second-line chemotherapy showed health utility similar to that at quasi-baseline, whereas utility values related to second-line targeted therapy were higher at 3 to 6 months and 6 months and beyond (β = 0.07, p = 0.010 and β = 0.07, p < 0.001, respectively). There was convergent validity between the utility values and scores of the physical and psychological domains.ConclusionTargeted therapy provided treated patients with a higher health utility value than was provided to those treated with chemotherapy. Development of the longitudinal trajectory may help predict changes in QoL and improve the care of lung cancer survivors.  相似文献   
7.
BackgroundAlthough preoperative anemia has been suggested to predict postsurgical morbidity and mortality among infants < 1 year of age, the data were drawn from heterogeneous patient cohorts including severely ill infants undergoing complex, high-risk procedures. We aimed to determine whether untreated preoperative anemia was associated with increased risk of postoperative complications in infants < 1 year of age who underwent pyloromyotomy, a common and relatively simple surgery.MethodsInfants < 1 year of age undergoing pyloromyotomy were identified from the American College of Surgeons (ACS) National Surgical Quality Improvement Program-Pediatric database. Preoperative anemia was defined as a hematocrit ≤ 40% for infants 0–30 days of age and ≤ 30% for infants more than 30 days of age. Patients who received pre- or postoperative blood transfusions were excluded.ResultsWe identified 2948 patients who met our inclusion criteria, of whom 843 were anemic (29%). The overall rate of complications in this cohort was 6%. The most common postoperative complications were readmission (97 cases), surgical site infection (43), reoperation (39), prolonged hospital stay (24), urinary tract infection (3), 30-day mortality (3) and cardiac arrest (2). We found no differences in the incidence of complications in anemic versus nonanemic patients on bivariate analysis or multivariable logistic regression (adjusted odds ratio = 1.2; 95% confidence interval: 0.8–1.7; P = 0.319).ConclusionsIn relatively healthy infants undergoing pyloromyotomy, untreated preoperative anemia was not associated with postoperative compilations and should not be considered a significant risk factor.Level of evidence III.  相似文献   
8.
IntroductionLumbar paragangliomas are rare, vascular, neuroendocrine tumors. They are notoriously difficult to diagnose radiologically and can prove challenging to manage intraoperatively, if capable of catecholamine secretion.Case reportWe report the case of a 45-year-old man, who presented with a lumbar spinal paraganglioma. The patient described a 2-year history of worsening lower back pain and sciatica. Neurological examination was normal. MRI revealed a lesion at L3, with prominent vessels, compressing the cauda equina. Gross total resection (GTR) of the tumor was performed. The patient recovered well, with relief of pain and no neurological deficit.DiscussionA literature search of lumbar paraganglioma cases, from January 1970 to April 2018 was carried out. Results of this review highlighted the importance of inclusion of paraganglioma as a differential diagnosis in lumbar spinal tumor and also the requirement for preoperative investigations to determine any potential secretory activity.ConclusionsLumbar paraganglioma behavior is most commonly benign and rates of recurrence are low after GTR. However, long-term postoperative follow-up is crucial, due to findings of late metastatic recurrence.  相似文献   
9.
The pituitary tumor-transforming gene 1 (PTTG1), also known as Securin, is considered an oncogene. This study aimed to investigate the role of PTTG1 in clear cell renal cell carcinoma (ccRCC) using in silico bioinformatics approaches. A pan-cancer analysis using The Cancer Genome Atlas (TCGA) data indicated that among all cancer types copy number amplification of PTTG1 gene was most frequently found in ccRCC. However, amplification of PTTG1 gene copy number did not correlate with the increase of mRNA level in ccRCC, and did not predict the patients' overall survival. Instead, ccRCC was correlated with overexpression of PTTG1 mRNA, and its expression level was stage-dependent increased in cancer patients. An outlier analysis using the Oncomine database suggested that PTTG1 mRNA expression served as a good biomarker for ccRCC. Pathway analysis for upregulated genes enriched in PTTG1-high expressing ccRCC patients found that PTTG1 overexpression was associated with mitotic defects. Mining drug sensitivity data using the Cancer Therapeutics Response Portal (CTRP) discovered that PTTG1-high expressing ccRCC cell lines were susceptible to a Rac1 (Ras-related C3 botulinum toxin substrate 1) inhibitor NSC23766. Therefore, this study provides an in silico insight into the role of PTTG1 in ccRCC, and repurposes the Rac1 inhibitor NSC23766 for treating PTTG1-high expressing ccRCC.  相似文献   
10.
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