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   1819篇
  免费   163篇
  国内免费   1篇
耳鼻咽喉   29篇
儿科学   32篇
妇产科学   100篇
基础医学   228篇
口腔科学   35篇
临床医学   280篇
内科学   251篇
皮肤病学   1篇
神经病学   200篇
特种医学   76篇
外科学   218篇
综合类   70篇
一般理论   7篇
预防医学   229篇
眼科学   17篇
药学   138篇
肿瘤学   72篇
  2022年   9篇
  2021年   33篇
  2020年   17篇
  2019年   36篇
  2018年   40篇
  2017年   32篇
  2016年   29篇
  2015年   32篇
  2014年   38篇
  2013年   83篇
  2012年   96篇
  2011年   107篇
  2010年   70篇
  2009年   67篇
  2008年   97篇
  2007年   92篇
  2006年   93篇
  2005年   84篇
  2004年   93篇
  2003年   84篇
  2002年   72篇
  2001年   69篇
  2000年   81篇
  1999年   53篇
  1998年   15篇
  1997年   14篇
  1996年   15篇
  1994年   8篇
  1993年   8篇
  1992年   39篇
  1991年   30篇
  1990年   23篇
  1989年   32篇
  1988年   24篇
  1987年   16篇
  1986年   15篇
  1985年   25篇
  1984年   14篇
  1983年   9篇
  1982年   12篇
  1981年   12篇
  1980年   16篇
  1979年   19篇
  1978年   18篇
  1977年   12篇
  1976年   9篇
  1975年   14篇
  1974年   16篇
  1971年   8篇
  1969年   8篇
排序方式: 共有1983条查询结果,搜索用时 15 毫秒
51.

Purpose

The use of internal iliac artery balloons for prevention of hemorrhage in cases of placenta accreta is increasing. Most described complications of this technique are maternal and thromboembolic in nature. Complications related to vascular rupture are rare, their presentation is not well described, and the resultant neonatal consequences are infrequently reported.

Clinical features

A 35-yr-old term parturient with suspected placenta accreta underwent prophylactic endovascular placement of iliac balloons prior to Cesarean delivery. The patient complained of contraction-like pain during balloon placement, and an arterial wall tear was discovered after abdominal incision. This produced significant maternal bleeding and the birth of a neonate with an umbilical venous pH of 6.95 and Apgar scores of 3 and 7.

Conclusion

In addition to the known maternal risks, fetal risks must be considered when planning the placement of endovascular iliac balloons during pregnancy. We recommend continuous monitoring of maternal and fetal status when performing the procedure. Contraction-like pain during placement should raise the suspicion of arterial disruption.  相似文献   
52.
Research digest     
Alzheimer's disease is a degenerative disease characterised by a progressive loss of cognitive functions and impairment of activities of daily living severe enough to interfere with normal functioning. To help persons with this disease perform a variety of activities, our research team developed AP@LZ, an electronic organiser specifically designed for them. Two participants with Alzheimer's disease learned how to use AP@LZ in their daily lives by following a structured learning method. After the learning phase, the participants were able to use AP@LZ efficiently and facilitate their day-to-day activities for several months, despite the steady progression of the disease. These results suggest that persons with Alzheimer's disease can learn to use new technologies to compensate for their everyday memory problems, which opens up new rehabilitation possibilities in dementia care.  相似文献   
53.
54.
Journal of Autism and Developmental Disorders - This study proposes a revision (R) of the Center for Epidemiologic Studies Depression Scale for youth with ID (CESD-ID) in English and French. 346...  相似文献   
55.
OBJECTIVE: To assess cardiac autonomic and respiratory changes from stage 2 non-rapid eye movement sleep (NREM) to rapid eye movement (REM) sleep in subjects with idiopathic REM sleep behavior disorder (RBD) and controls. We tested the hypothesis that REM-related cardiorespiratory activation is altered in subjects with RBD. DESIGN: Retrospective case-control study. SETTING: University hospital-based sleep research laboratory. PATIENTS: Ten subjects with idiopathic RBD (2 women, mean age 63.4 +/- 6.2 years) and 10 sex- and age-matched controls (mean age 63.9 +/- 6.3 years). INTERVENTION: One-night polysomnography was used to assess R-R variability during NREM and REM sleep. MEASUREMENTS AND RESULTS: Spectral analysis of R-R interval and respiration were performed. Mean R-R interval, low-frequency (LF) and high-frequency (HF) components in both absolute and normalized units (LFnu and HFnu), and the LF/HF ratio were obtained from 5-minute electrocardiogram segments selected during NREM and REM sleep under stable conditions (stable breathing pattern, no microarousals or leg movements). Respiratory frequency was also assessed. Values obtained were then averaged for each stage and analyzed by 2 x 2 analysis of variance with group (RBD subjects and controls) as factor and state (NREM and REM) as repeated measures. RR interval, HF, and HFnu components decreased from NREM to REM in controls but did not change in RBD subjects (Interaction P < 0.05). LFnu (interaction P < 0. 001), LF/HF (interaction P < 0. 001), and respiratory frequency (interaction P < 0. 05) increased from NREM to REM sleep in controls but remained stable in RBD subjects. CONCLUSION: REM-related cardiac and respiratory responses are absent in subjects with idiopathic RBD.  相似文献   
56.
BACKGROUND: Group B streptococci (GBS) are a leading cause of sepsis and meningitis in newborns. We previously developed a rapid diagnostic system for GBS detection from vaginal/anal samples obtained from pregnant women during delivery. To facilitate the adaptation of this method for point-of-care testing, we have developed a specific and efficient GBS DNA capture method that is compatible with both PCR and nonamplification detection technologies. METHODS: Superparamagnetic beads were functionalized with oligonucleotide capture probes of different lengths and used to capture GBS genomic DNA (gDNA). A rapid extraction procedure was used to provide DNA from GBS cultures or vaginal/anal samples with added GBS. Hybridization reactions consisting of functionalized beads and target DNA in 30 muL of hybridization buffer were performed for 1 h at room temperature, followed by washing and resuspension in water. Captured DNA was then detected using quantitative PCR. RESULTS: A 25-mer capture probe allowed detection of 1000 genome copies of purified GBS DNA. The ability to detect GBS was improved by use of a 50-mer (100 copies) and a 70-mer capture probe (10 copies). Detection of approximately 1250 CFU/mL was achieved for diluted GBS broth culture and for vaginal/anal swab samples with added GBS. CONCLUSION: Oligonucleotide-functionalized superparamagnetic microbeads efficiently capture GBS gDNA from both bacterial cultures and vaginal/anal samples with added GBS. Efficiency of gDNA capture increases with oligonucleotide length. This technology could be combined with sample preparation and detection technologies in a microfluidic system to allow point-of-care testing for GBS.  相似文献   
57.
Adipose tissue is a major regulator of bone metabolism and in the general population obesity is associated with greater bone mineral density (BMD). However, bone‐fat interactions are multifactorial, and may involve pathways that influence both bone formation and resorption with competing effects on the skeleton. One such pathway involves adipocyte production of adipokines that regulate bone metabolism. In this study we determined the association between BMD, walking status, and circulating adipokines (adiponectin and leptin) in 149 men with chronic spinal cord injury (SCI). Although adipokine levels did not vary significantly based on walking status, there was a significant inverse association between adiponectin and BMD in wheelchair users independent of body composition. We found no association between adiponectin and BMD in the walkers and no association between leptin and BMD in either group. These findings suggest that for subjects with chronic SCI, walking may mitigate the effect of adiponectin mediated bone loss. For wheelchair users, adipose‐derived adiponectin may contribute to SCI‐induced osteoporosis because the osteoprotective benefits of obesity appear to require mechanical loading during ambulation. © 2014 American Society for Bone and Mineral Research.  相似文献   
58.
ObjectivesTo examine associations between mild cognitive impairment (MCI) and falls among primary care patients, and to investigate whether social engagement (SE) modifies these associations.DesignCross sectional analysis using baseline data from an observational cohort study.SettingPrimary care.ParticipantsCommunity-dwelling older adults (N=430) at risk of mobility decline with a mean age of 76.6 years (range 65-96y).Main Outcome MeasuresThe number of falls in the past year was reported at the baseline interview. MCI was identified using a cutoff of 1.5 SD below the age-adjusted mean on at least 2 of the standardized cognitive performance tests. SE (eg, keeping in touch with friends and family, volunteering, participating social activities…) was assessed with the Late Life Function and Disability Instrument, and required a score above the median value 49.5 out of 100.ResultsMCI was present among 42% of participants and 42% reported at least 1 fall in the preceding year. Using generalized estimating equations, MCI was associated with a 77% greater rate of falls (P<.05). There was a statistically significant interaction between SE and MCI on the rate of falls (P<.01), such that at a high level of SE, MCI was not statistically associated with falls (P=.83). In participants with lower levels of SE, MCI is associated with 1.3 times greater rate of falls (P<.01).ConclusionsWhile MCI is associated with a greater risk for falls, higher levels of SE may play a protective role.  相似文献   
59.
60.
The term vaccine hesitancy refers to delay in acceptance or refusal of vaccines despite the availability of vaccination services. Different factors influence vaccine hesitancy and these are context-specific, varying across time and place and with different vaccines. Factors such as complacency, convenience and confidence are involved. Acceptance of vaccines may be decreasing and several explanations for this trend have been proposed. The WHO Strategic Advisory Group of Experts (SAGE) on Immunization has recognized the global importance of vaccine hesitancy and recommended an interview study with immunization managers (IMs) to better understand the range of vaccine hesitancy determinants that are encountered in different settings. Interviews with IMs in 13 selected countries were conducted between September and December 2013 and various factors that discourage vaccine acceptance were identified. Vaccine hesitancy was not defined consistently by the IMs and most interpreted the term as meaning vaccine refusal. Although vaccine hesitancy existed in all 13 countries, some IMs considered its impact on immunization programmes to be a minor problem. The causes of vaccine hesitancy varied in the different countries and were context-specific, indicating a need to strengthen the capacity of national programmes to identify the locally relevant causal factors and to develop adapted strategies to address them.  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