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   4483篇
  免费   414篇
  国内免费   9篇
耳鼻咽喉   68篇
儿科学   107篇
妇产科学   87篇
基础医学   624篇
口腔科学   137篇
临床医学   632篇
内科学   701篇
皮肤病学   65篇
神经病学   617篇
特种医学   114篇
外科学   585篇
综合类   48篇
一般理论   15篇
预防医学   539篇
眼科学   78篇
药学   311篇
中国医学   9篇
肿瘤学   169篇
  2023年   46篇
  2022年   88篇
  2021年   180篇
  2020年   120篇
  2019年   182篇
  2018年   212篇
  2017年   115篇
  2016年   123篇
  2015年   125篇
  2014年   183篇
  2013年   255篇
  2012年   281篇
  2011年   346篇
  2010年   169篇
  2009年   166篇
  2008年   243篇
  2007年   227篇
  2006年   198篇
  2005年   193篇
  2004年   138篇
  2003年   150篇
  2002年   125篇
  2001年   93篇
  2000年   88篇
  1999年   73篇
  1998年   26篇
  1996年   20篇
  1995年   21篇
  1994年   23篇
  1992年   27篇
  1991年   45篇
  1990年   33篇
  1989年   33篇
  1988年   37篇
  1987年   46篇
  1986年   28篇
  1985年   20篇
  1984年   23篇
  1983年   26篇
  1981年   17篇
  1979年   25篇
  1978年   28篇
  1976年   17篇
  1974年   24篇
  1973年   22篇
  1972年   24篇
  1971年   18篇
  1970年   23篇
  1968年   18篇
  1967年   21篇
排序方式: 共有4906条查询结果,搜索用时 15 毫秒
101.
Journal of Neurology - Individuals with pre-existing chronic illness have shown increased anxiety and depression due to COVID-19. Here, we examine the impact of the COVID-19 pandemic on emotional...  相似文献   
102.
How to cite this article: Sabharwal P, Chakraborty S, Tyagi N, Kumar A. Acute Flaccid Quadriparesis in a Recovering COVID-19 Patient: A Clinical Dilemma. Indian J Crit Care Med 2021;25(2):238–239.  相似文献   
103.
The immobilisation and disposal of fissile materials from civil and defence nuclear programmes requires compatible, passively safe and proliferation resistant wasteforms. In this study, we demonstrate the application of an albite glass–zirconolite ceramic material for immobilisation of chloride contaminated plutonium oxide residues in the United Kingdom. The chlorine solubility limit in the albite glass phase was determined to be 1.0 ± 0.1 wt%, above the maximum envisaged chorine inventory of 0.5 wt%, attainable at a 20 wt% PuO2 incorporation rate within the ceramic. Cl K-edge of X-ray Absorption Near Edge Spectroscopy (XANES) was exploited to confirm partitioning of Cl to the glass phase, speciated as the chloride anion, with exsolution of crystalline NaCl above the chlorine solubility limit. Combinatorial fitting of Cl XANES data, utilising a library of chemically plausible reference spectra, demonstrated the association of Cl with Na and Ca modifier cations, with environments characteristic of the aluminosilicate chloride minerals eudialyte, sodalite, chlorellestadite and afghanite. Adventitious incorporation of Ca, Zr and Ti within the albite glass phase apparently assists chlorine solubility, by templating a local chemical environment characteristic of the mineral reference compounds. The partitioning of Ce, as a Pu analogue, within the glass–ceramic was not adversely impacted by incorporation of Cl. The significance of this research is in demonstrating the compatibility of the glass–ceramic wasteform toward Cl solubility at the expected incorporation rate, below the determined solubility limit. Thus, an upstream heat treatment facility to remove chloride contamination, as specified in the current conceptual flowsheet, would not be required from the perspective of wasteform compatibility, thus providing scope to de-risk the technology roadmap and reduce the projected capital and operational plant costs.

Understanding chlorine speciation and incorporation in glass ceramic wasteforms underpins future treatment of contaminated plutonium residues.  相似文献   
104.

Background

There is increased awareness that, to minimize variation in clinician practice and improve quality, performance reporting should be implemented at the provider level. This optimizes physician engagement and creates a sense of professional responsibility for quality and performance measurement at the individual and organizational levels.

Methods

Individual provider level reporting was implemented within a provincial health region involving 56 clinicians (general surgeons, surgical oncologists, urologists and pathologists). The 2 surgical pathology indicators chosen were colorectal cancer (CRC) lymph node retrieval rate and pT2 prostate cancer margin positivity rate. Surgical resections for all prostate and colorectal cancer performed between Jan. 1, 2011, and Mar. 30, 2012, were included. We used a pre- and postsurvey design to obtain physician perceptions and focus groups with program leadership to determine organizational impact.

Results

Survey results showed that respondents felt the data provided in the reports were valid (67%), consistent with expectations (70%), maintained confidentiality (80%) and were not used in a punitive manner (77%). During the study period the pT2 prostate margin positivity rate decreased from 57.1% to 27.5%. For the CRC lymph node retrieval rate indicator, high baseline performance was maintained.

Conclusion

We developed a robust process for providing physicians with confidential, individualized surgical and pathology quality indicator reports. Our results reinforce the importance of individual physician feedback as a strategy for improving and sustaining quality in surgical and diagnostic oncology.  相似文献   
105.
Roux‐en‐Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2D‐mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m2). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6‐month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24‐hour urinary Ca decreased, PTH increased, and 1,25(OH)2D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = ?0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long‐term skeletal consequences should be investigated. © 2015 American Society for Bone and Mineral Research.  相似文献   
106.
Although two dimensional echocardiography can detect left ventricular thrombi In certain cardiovascular disease states, there Is theoretical concern that the acoustic Impedance properties of recently formed fresh thrombi may not allow their echocardiographic visualization. If such were the case, false negative studies might occur even with technically adequate echocardiographic examinations. To determine if the tissue acoustic properties of acute thrombi allow their visualization and differentiation from surrounding intracavitary blood and adjacent myocardium with two dimensional echocardiography, an in vivo canine model of acute left ventricular thrombus was studied. In 10 dogs left ventricular thrombus was induced using coronary ligation and subendocardial injection of a sclerosing agent, sodium rlclnoleate. Acoustically distinct left ventricular thrombi were imaged by two dimensional echocardiography within hours (mean ± standard deviation 121 ± 40 minutes, range 45 to 180), and the thrombi could easily be differentiated from surrounding blood and adjacent myocardium. Thrombi with a maximal dimension as small as 0.6 cm at autopsy were highly reflective and could be imaged with echocardiography. Histologic examination of the thrombi showed characteristic features of early thrombosis. In six dogs, echocardiographic imaging revealed two acoustically distinct areas of thrombi. Gross and microscopic examination of the thrombi in these animals confirmed two distinct types of thrombus with differing histologie features.Although technical aspects of the echocardiographic examination or certain biologic features of thrombi such as thrombus size may limit the detection of thrombi by echocardiography in certain situations, our data indicate that the tissue acoustic properties of recently formed thrombi are not a primary limitation to their echocardiographic detection. These findings support the use of two dimensional echocardiography in the investigation of the natural history, prevention and therapy of left ventricular thrombus in patients during the early course of acute myocardial Infarction.  相似文献   
107.
Artemether (ART) is a well-described antimalarial with efficacy against juvenile schistosomes, with 7-day-old schistosomula being particularly susceptible. Both ART-affected worms and parasites developing from irradiated cercariae die at similar times after infection. Our aim was to determine if ART treatment of prepatent schistosomiasis japonica may result in the generation of a protective immune response. Female CBA mice were treated with a single dose of ART at defined time points after percutaneous infection with a virulent Chinese mainland strain of Schistosoma japonicum. Half of the mouse cohorts were subjected to homologous parasite strain reinfection after drug treatment to assess protective effects of ART therapy. Two independent trials demonstrated that a statistically significant (58% and 50%) reduction in challenge worm burden occurred after reinfection of those mice treated with ART at two weeks p.i. A reduction in the IL-4 response to soluble worm antigen preparation (SWAP) was also seen in ART-treated mice but with no correlation to reinfection resistance. In the Chinese mainland strain used, ART treatment of prepatent infection at the appropriate time point induced resistance to reinfection. There was also an anti-pathology effect observed in ART-treated mice that remained significant after reinfection.  相似文献   
108.
109.
110.
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