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   1487篇
  免费   157篇
  国内免费   9篇
耳鼻咽喉   14篇
儿科学   47篇
妇产科学   36篇
基础医学   234篇
口腔科学   56篇
临床医学   217篇
内科学   305篇
皮肤病学   34篇
神经病学   111篇
特种医学   18篇
外科学   180篇
综合类   61篇
一般理论   1篇
预防医学   132篇
眼科学   25篇
药学   95篇
中国医学   5篇
肿瘤学   82篇
  2023年   14篇
  2022年   35篇
  2021年   84篇
  2020年   41篇
  2019年   49篇
  2018年   59篇
  2017年   37篇
  2016年   45篇
  2015年   39篇
  2014年   51篇
  2013年   60篇
  2012年   94篇
  2011年   104篇
  2010年   55篇
  2009年   56篇
  2008年   64篇
  2007年   62篇
  2006年   66篇
  2005年   74篇
  2004年   54篇
  2003年   52篇
  2002年   57篇
  2001年   24篇
  2000年   26篇
  1999年   32篇
  1998年   15篇
  1997年   12篇
  1996年   14篇
  1995年   6篇
  1992年   23篇
  1991年   21篇
  1990年   16篇
  1989年   14篇
  1988年   15篇
  1987年   18篇
  1986年   10篇
  1985年   21篇
  1984年   13篇
  1983年   12篇
  1982年   6篇
  1981年   5篇
  1980年   8篇
  1979年   13篇
  1978年   9篇
  1977年   5篇
  1974年   6篇
  1972年   7篇
  1970年   6篇
  1968年   4篇
  1967年   12篇
排序方式: 共有1653条查询结果,搜索用时 125 毫秒
61.
62.
Objectives:To evaluate the impact of COVID-19 on cancer management in Saudi Arabia’s military hospitals.Methods:This multi-centric, retrospective study compared cancer patients diagnosed from February-July 2019 and 2020, focusing on the time duration for acceptance and time for oncologic treatment initiation. Eligibility and referral status were recorded. Clinical data of COVID-19-positive cancer patients were collected and evaluated their outcomes and survival.Results:Data of 1574 cancer patients (mean age, 57.1 years) were collected. Mean time for acceptance was 7.3 days in 2019 and 8 days in 2020, with no statistically significant difference. Mean time for oncology treatment initiation was 38.4 days in 2019 and 44.3 days in 2020, with no statistically significant difference. The number of new cancer patients decreased in 2020 but increased in peripheral hospitals. It decreased in Riyadh and Jeddah hospitals. Concerning referral status, a statistically significant modification was recorded only in Riyadh and Tabuk hospitals. No significant changes observed in time duration for acceptance of new patients and oncology treatment initiation from 2019-2020. A total of 76 COVID-19-positive cancer patients recorded; 72% were symptomatic, 73.6% recovered, 22.3% died due to COVID-19 complications, and 8% died due to cancer; cancer progressed in 7 patients.Conclusion:COVID-19 did not affect oncology service in Saudi Arabia’s military hospitals. New cancer cases reduced during the pandemic. Cancer patients are at increased risk for COVID-19 complications, including death.  相似文献   
63.
The purpose of this study was to assess changes in cervical musculature throughout contact-heavy collegiate ice hockey practices during a regular season of NCAA Division III ice hockey teams. In this cross-sectional study, 36 (male n = 13; female n = 23) ice hockey players participated. Data were collected over 3 testing sessions (baseline; pre-practice; post-practice). Neck circumference, neck length, head-neck segment length, isometric strength and electromyography (EMG) activity for flexion and extension were assessed. Assessments were completed approximately 1h before a contact-heavy practice and 15 min after practice. For sternocleidomastoid (SCM) muscles, males had significantly greater peak force and greater time to peak force versus females. For both left and right SCMs, both sexes had significantly greater peak EMG activity pre-practice versus baseline, and right (dominant side) SCM time to peak EMG activity was decreased post-practice compared to pre-practice. There were no significant differences for EMG activity of the upper trapezius musculature, over time or between sexes. Sex differences observed in SCM force and activation patterns of the dominant side SCM may contribute to head stabilization during head impacts. Our study is the first investigation to report changes in cervical muscle strength in men’s and women’s ice hockey players in the practical setting. Key points
  • Concussion prevention strategies, such as cervical muscle strength and activation time, was investigated in the practical setting.
  • Neck muscle fatigue may not be a contributing factor to a concussive event in contact sports such as ice hockey.
  • Hand dominance may affect recruitment timing of neck musculature, which can affect the cervical muscle activation response.
  • Males and females exhibited differences in sternocleidomastoid time to peak force.
Key words: Ice hockey, sternocleidomastoid, sex differences, neck strength  相似文献   
64.

Objective

Early stroke recognition optimizes patients' opportunities to benefit from therapeutic options. Prehospital stroke recognition is suboptimal. If 9-1-1 dispatchers used stroke-identification tools, prehospital stroke recognition might occur more rapidly and accurately. The Cincinnati Prehospital Stroke Scale (CPSS) is a brief, effective tool used by emergency medical services and hospital personnel to identify stroke. The study's goal was to determine whether laypersons could be instructed to use the CPSS over the telephone.

Methods

Adult visitors (laypersons) to a tertiary care emergency department were enrolled. Using a mock patient, laypersons were instructed to use the CPSS via telephone by an investigator simulating a 9-1-1 dispatcher. The patient randomly portrayed clinically normal and abnormal patient types. The layperson's ability to convey CPSS instructions to the patient and relay findings to the investigator was scored.

Results

Seventy laypersons were enrolled (35 each for normal and abnormal patient types). Average age was 48 years, 63% were female, and 40% never attended college. Facial droop and speech instructions were administered with 100% accuracy. Arm drift instructions were administered with 99% accuracy. Layperson accuracies for interpreting findings were 93% for facial droop, 93% for arm drift, and 97% for speech. Overall, stroke symptoms were detected with 94% sensitivity (95% CI 87, 100) and 83% specificity (95% CI 70, 95).

Conclusion

Laypersons correctly administered and interpreted the CPSS when directed to do so over the telephone by a trained investigator. These findings suggest that the CPSS may be a useful tool in early prehospital detection of stroke by dispatchers.  相似文献   
65.
The bone marrow (BM) microenvironment regulates acute myeloid leukemia (AML) initiation, proliferation, and chemotherapy resistance. Following cancer cell death, a growing body of evidence suggests an important role for remaining apoptotic debris in regulating the immunologic response to and growth of solid tumors. Here, we investigated the role of macrophage LC3–associated phagocytosis (LAP) within the BM microenvironment of AML. Depletion of BM macrophages (BMMs) increased AML growth in vivo. We show that LAP is the predominate method of BMM phagocytosis of dead and dying cells in the AML microenvironment. Targeted inhibition of LAP led to the accumulation of apoptotic cells (ACs) and apoptotic bodies (ABs), resulting in accelerated leukemia growth. Mechanistically, LAP of AML-derived ABs by BMMs resulted in stimulator of IFN genes (STING) pathway activation. We found that AML-derived mitochondrial damage–associated molecular patterns were processed by BMMs via LAP. Moreover, depletion of mitochondrial DNA (mtDNA) in AML-derived ABs showed that it was this mtDNA that was responsible for the induction of STING signaling in BMMs. Phenotypically, we found that STING activation suppressed AML growth through a mechanism related to increased phagocytosis. In summary, we report that macrophage LAP of apoptotic debris in the AML BM microenvironment suppressed tumor growth.  相似文献   
66.
67.
ABSTRACT

If much has been written of the forms of bodiliness reinforced by hospitals, less attention has been paid to the medicalization of the soul. The medical management of death institutionalizes divisions between body and soul, and matter and spirit, infusing end-of-life care with latent Christian theological presumptions. The invisibility of these presumptions is partly sustained by projecting religiosity on those who endorse other cosmologies, while retaining for medicine a mask of secular science. Stories of conflict with non-Christian patients force these presumptions into visibility, suggesting alternative ethics of care and mourning rooted in other understandings. In this article, I explore one such story. Considering the story as an allegory for how matter and spirit figure in contemporary postmortem disciplines, I suggest that it exposes both the operation of a taboo against mixing material and spiritual agendas, and an assumption that appropriate mourning is oriented toward symbolic homage, rather than concern for the material welfare of the dead.  相似文献   
68.
Soluble syndecan-1 promotes growth of myeloma tumors in vivo   总被引:11,自引:3,他引:11       下载免费PDF全文
Syndecan-1 (CD138) is a transmembrane heparan sulfate-bearing proteoglycan expressed by most myeloma plasma cells that regulates adhesion, migration, and growth factor activity. In patients with myeloma, shed syndecan-1 accumulates in the bone marrow, and high levels of syndecan-1 in the serum are an indicator of poor prognosis. To test the effect of soluble syndecan-1 on tumor cell growth and dissemination, ARH-77 B-lymphoid cells were engineered to produce a soluble form of syndecan-1. Controls included vector only (neo)-transfected cells and cells transfected with full-length syndecan-1 complementary DNA that codes for the cell surface form of syndecan-1. Assays reveal that all 3 transfectants have similar growth rates in vitro, but cells expressing soluble syndecan-1 are hyperinvasive in collagen gels relative to controls. When injected into the marrow of human bones that were implanted in severe combined immunodeficient mice, tumors formed by cells expressing soluble syndecan-1 grow faster than tumors formed by neo-transfected cells or by cells expressing cell surface syndecan-1. In addition, cells bearing cell surface syndecan-1 exhibit a diminished capacity to establish tumors within the mice as compared with both neo- and soluble syndecan-1-transfected cells. Tumor cell dissemination to a contralateral human bone is detected significantly more often in the tumors producing soluble syndecan-1 than in controls. Thus, high levels of soluble syndecan-1 present in patients with myeloma may contribute directly to the growth and dissemination of the malignant cells and thus to poor prognosis.  相似文献   
69.
Improved laboratory diagnosis is critical to reduce the burden of malaria in pregnancy. Peripheral blood smears appear less sensitive than Plasmodium falciparum histidine-rich protein 2-based rapid diagnostic tests (RDTs) for placental malaria infections in studies conducted at delivery. In this study, 81 women in Uganda in the second or third trimester of pregnancy were followed-up until delivery. At each visit, peripheral blood was tested by blood smear, RDT, and nested species-specific polymerase chain reaction (PCR). Sensitivity and specificity of the tests was calculated with PCR, which detected 22 infections of P. falciparum, as the gold standard. The sensitivity and specificity of blood smears were 36.4% (95% confidence interval [CI] = 18.0-59.2%) and 99.6% (95% CI = 97.7-100%), respectively. The corresponding values for RDT were 31.8% (95% CI = 14.7-54.9%) and 100% (95% CI = 98.3-100%). The RDTs could replace blood smears for diagnosis of malaria in pregnancy by virtue of their relative ease of use. Field-based sensitive tests for malaria in pregnancy are urgently needed.  相似文献   
70.
During HIV infection of the CNS, neurons are damaged by viral proteins, such as Tat and gp120, or by inflammatory factors, such as TNF-α, that are released from infected and/or activated glial cells. Host responses to this damage may include the induction of survival or repair mechanisms. In this context, previous studies report robust expression of a protein called particularly interesting new cysteine histidine-rich protein (PINCH), in the neurons of HIV patients’ brains, compared with nearly undetectable levels in HIV-negative individuals (Rearden et al., J Neurosci Res 86:2535–2542, 2008), suggesting PINCH’s involvement in neuronal signaling during HIV infection of the brain. To address potential triggers for PINCH induction in HIV patients’ brains, an in vitro system mimicking some aspects of HIV infection of the CNS was utilized. We investigated neuronal PINCH expression, subcellular distribution, and biological consequences of PINCH sequestration upon challenge with Tat, gp120, and TNF-α. Our results indicate that in neurons, TNF-α stimulation increases PINCH expression and changes its subcellular localization. Furthermore, PINCH mobility is required to maintain neurite extension upon challenge with TNF-α. PINCH may function as a neuron-specific host-mediated response to challenge by HIV-related factors in the CNS.  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