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   4135篇
  免费   273篇
  国内免费   36篇
耳鼻咽喉   50篇
儿科学   117篇
妇产科学   163篇
基础医学   521篇
口腔科学   74篇
临床医学   444篇
内科学   939篇
皮肤病学   69篇
神经病学   284篇
特种医学   413篇
外科学   554篇
综合类   88篇
预防医学   298篇
眼科学   30篇
药学   238篇
中国医学   4篇
肿瘤学   158篇
  2021年   38篇
  2020年   37篇
  2019年   48篇
  2018年   53篇
  2017年   52篇
  2016年   47篇
  2015年   62篇
  2014年   84篇
  2013年   116篇
  2012年   144篇
  2011年   168篇
  2010年   99篇
  2009年   80篇
  2008年   127篇
  2007年   197篇
  2006年   180篇
  2005年   164篇
  2004年   201篇
  2003年   168篇
  2002年   180篇
  2001年   160篇
  2000年   198篇
  1999年   152篇
  1998年   57篇
  1997年   48篇
  1996年   50篇
  1995年   33篇
  1994年   38篇
  1992年   101篇
  1991年   92篇
  1990年   97篇
  1989年   62篇
  1988年   54篇
  1987年   70篇
  1986年   53篇
  1985年   66篇
  1984年   48篇
  1983年   44篇
  1982年   32篇
  1979年   48篇
  1978年   33篇
  1977年   31篇
  1976年   27篇
  1974年   34篇
  1973年   33篇
  1971年   39篇
  1970年   28篇
  1969年   26篇
  1968年   28篇
  1967年   29篇
排序方式: 共有4444条查询结果,搜索用时 46 毫秒
141.
142.
143.
Q fever, caused by the zoonotic bacterium Coxiella burnetii, is a globally distributed emerging infectious disease. Livestock are the most important zoonotic transmission sources, yet infection in people without livestock exposure is common. Identifying potential exposure pathways is necessary to design effective interventions and aid outbreak prevention. We used natural language processing and graphical network methods to provide insights into how Q fever notifications are associated with variation in patient occupations or lifestyles. Using an 18‐year time‐series of Q fever notifications in Queensland, Australia, we used topic models to test whether compositions of patient answers to follow‐up exposure questionnaires varied between demographic groups or across geographical areas. To determine heterogeneity in possible zoonotic exposures, we explored patterns of livestock and game animal co‐exposures using Markov Random Fields models. Finally, to identify possible correlates of Q fever case severity, we modelled patient probabilities of being hospitalized as a function of particular exposures. Different demographic groups consistently reported distinct sets of exposure terms and were concentrated in different areas of the state, suggesting the presence of multiple transmission pathways. Macropod exposure was commonly reported among Q fever cases, even when exposure to cattle, sheep or goats was absent. Males, older patients and those that reported macropod exposure were more likely to be hospitalized due to Q fever infection. Our study indicates that follow‐up surveillance combined with text modelling is useful for unravelling exposure pathways in the battle to reduce Q fever incidence and associated morbidity.  相似文献   
144.
Islet yield is an important predictor of acceptable glucose control after total pancreatectomy with islet autotransplantation (TP-IAT). We assessed if pancreas volume calculated with preoperative MRI could assess islet yield and postoperative outcomes. We reviewed dynamic MRI studies from 154 adult TP-IAT patients (2009-2016), and associations between calculated volumes and digest islet equivalents (IEQs) were tested. In multivariate regression analysis, pancreas volume (P < .001) and preoperative HbA1c levels (P = .009) were independently associated with digest IEQs. The IEQ prediction formula was calculated according to each preoperative HbA1c level, (a) pancreas volume × 5800 for HbA1c ≥ 6.5, (b) pancreas volume × 10 000 for HbA1c ≥5.7/<6.5 and (iii) pancreas volume × 11 400 for HbA1c < 5.7. The formula was internally validated with 28 TP-IAT patients between 2017 and 2018 (r2 = .657 and r2 = .710 when restricted to 24 patients without prior pancreatectomy). An estimated IEQs/Body Weight (kg) ≥3700 predicted HbA1c ≤6.5 and insulin independence at 1 year after TP-IAT with 77% and 88% sensitivity and 55% and 43% specificity, respectively. The combination of pancreas volume and preoperative HbA1c levels may be useful to estimate islet yield. Estimated IEQs were reasonably sensitive to predict acceptable glucose control at 1 year.  相似文献   
145.

Background

Gaps in breast cancer (BC) surgical care have been identified. We have completed a surgeon-directed, iterative project to improve the quality of BC surgery in South-Central Ontario.

Methods

Surgeons performing BC surgery in a single Ontario health region were invited to participate. Interventions included: audit and feedback (A&F) of surgeon-selected quality indicators (QIs), workshops, and tailoring interviews. Workshops and A&F occurred yearly from 2005–2012. QIs included: preoperative imaging; preoperative core biopsy; positive margin rates; specimen orientation labeling; intraoperative specimen radiography of nonpalpable lesions; T1/T2 mastectomy rates; reoperation for positive margins; sentinel lymph node biopsy (SLNB) rates, number of sentinel lymph nodes; and days to receive pathology report. Semistructured tailoring interviews were conducted to identify facilitators and barriers to improved quality. All results were disseminated to all surgeons performing breast surgery in the study region.

Results

Over 6 time periods, 1,828 BC charts were reviewed from 12 hospitals (8 community and 4 academic). Twenty-two to 40 participants attended each workshop. Sustained improvement in rates of positive margins, preoperative core biopsies, specimen orientation labeling, and SLNB were seen. Mastectomy rates and overall axillary staging rates did not change, whereas time to receive pathology report increased. The tailoring interviews concerning positive margins, SLNB, and reoperation for positive margins identified facilitators and barriers relevant to surgeons.

Conclusions

This surgeon-directed, regional project resulted in meaningful improvement in numerous QIs. There was consistent and sustained participation by surgeons, highlighting the importance of integrating the clinicians in a long-term, iterative quality improvement strategy in BC surgery.  相似文献   
146.
147.
148.
As people with intellectual and developmental disabilities (I/DD) age, it is important that I/DD agencies are prepared to support healthy ageing in homes and in communities. This study explored supports and barriers to sustaining community‐based health and participation initiatives (CBHPI) for people ageing with I/DD living in group homes managed by agencies. The study utilized interviews and photovoice with 70 participants—35 individuals with I/DD and 35 management/direct support agency staff. Data were analysed through content analysis and triangulation of data where five themes emerged: Agency values and policies related to healthy ageing; resources and staff competencies; communication between management and staff; community/university partnerships; and peer relations. Findings show that I/DD agencies and people with I/DD value CBHPI, but they find them difficult to sustain due to limited resources and lack of training specific to ageing with I/DD. Conducting system‐level research within I/DD agencies to include first‐person accounts of people with I/DD, staff and management provides insight on how to effectively support the needs of people with I/DD to improve their health and community participation as they age.  相似文献   
149.
We have demonstrated that controlled electric fields can be used to regulate transport, concentration, hybridization, and denaturation of single- and double-stranded oligonucleotides. Discrimination among oligonucleotide hybrids with widely varying binding strengths may be attained by simple adjustment of the electric field strength. When this approach is used, electric field denaturation control allows single base pair mismatch discrimination to be carried out rapidly (<15 sec) and with high resolution. Electric field denaturation takes place at temperatures well below the melting point of the hybrids, and it may constitute a novel mechanism of DNA denaturation.  相似文献   
150.
BACKGROUND & AIMS: Thiazolidinedione (TZD) therapy improves liver histology in nonalcoholic steatohepatitis (NASH) through a mechanism possibly related to its insulin-sensitizing or anti-inflammatory activity. This study was conducted to assess changes in serum levels of selected adipokines and proinflammatory cytokines and to relate these changes to the improved liver histology resulting from pioglitazone therapy for NASH. METHODS: Serum samples from 18 patients with NASH obtained at day 0 and week 48 of therapy during an open-label study of pioglitazone were tested for adiponectin, leptin, interleukin (IL)-1a, IL-6, and tumor necrosis factor (TNF)-alpha levels. Paired liver biopsy specimens were scored (0-4) for steatosis, parenchymal inflammation, cell injury, and fibrosis. RESULTS: Adiponectin levels increased from 3.7 to 10.3 mug/mL at week 48 (P < .01); the levels of the other cytokines were unchanged: TNF-alpha, 9.1 vs 8.8 pg/mL; IL-1a, 3.9 vs 3.4 pg/mL; IL-6, 19.4 vs 13.4 pg/mL; and leptin, 24.8 vs 29.6 ng/mL (P > .05 for all). Pioglitazone therapy was associated with improvements in steatosis (2.5 vs 1.0), parenchymal inflammation (3.3 vs 2.1), cell injury (2.2 vs 0.9), and fibrosis (2.0 vs 1.4). The change in adiponectin level was associated with the improvement in steatosis (P = .03) as well as in a summary NASH activity index score (P = .01). Changes in IL-1, IL-6, TNF-alpha, and leptin levels did not correlate with improvements in the histological features. CONCLUSIONS: Improvements in liver histology during TZD therapy may be modulated by an adiponectin-mediated effect on insulin sensitivity and hepatic fatty acid metabolism rather than by changes in proinflammatory cytokines.  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