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   1205篇
  免费   108篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   89篇
妇产科学   66篇
基础医学   125篇
口腔科学   29篇
临床医学   110篇
内科学   223篇
皮肤病学   55篇
神经病学   98篇
特种医学   39篇
外科学   104篇
综合类   8篇
一般理论   1篇
预防医学   77篇
眼科学   76篇
药学   114篇
中国医学   5篇
肿瘤学   90篇
  2024年   1篇
  2023年   26篇
  2022年   58篇
  2021年   73篇
  2020年   63篇
  2019年   80篇
  2018年   86篇
  2017年   61篇
  2016年   84篇
  2015年   54篇
  2014年   89篇
  2013年   92篇
  2012年   101篇
  2011年   103篇
  2010年   46篇
  2009年   45篇
  2008年   65篇
  2007年   63篇
  2006年   45篇
  2005年   28篇
  2004年   15篇
  2003年   6篇
  2002年   3篇
  2001年   1篇
  2000年   3篇
  1999年   7篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1994年   2篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1987年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
排序方式: 共有1315条查询结果,搜索用时 31 毫秒
21.
22.
Panama wilt, a deadly disease of banana in general and Silk group in particular, is creating havoc worldwide. Infected planting material being a major mode of disease spread, production of disease free quality planting material is a must for area expansion. Micropropagation offers a viable solution for overcoming this problem. Though protocols for micropropagation have been standardized for various varieties of banana, their in field trials along with the conventional propagules have seldom been made. This study deals with agronomic, phenological and post harvest attributes of in vitro propagated plantlets of Silk banana var. Nanjanagud Rasabale in comparison to their traditional counterparts. Tissue cultured plantlets were superior to sucker derived plants in terms of vegetative growth, yield and quality parameters. Further micropropagules were precocious by eight weeks and exhibited synchronized flowering.  相似文献   
23.
24.
Neuroinflammation plays a significant role in various chronic and acute pathological conditions of the central nervous system. In the Indian system of medicine, Pluchea lanceolata is used to treat the neurological disorders. We investigated the effect of major pentacyclic triterpene and its naturally occurring acetate derivative isolated from P. lanceolata on lipopolysaccharide (LPS)-stimulated neuroinflammatory condition associated to inflammatory cytokine production in rat astrocytoma cell line (C6). The log concentration dependence of Pluchea bioactive taraxasterol (Tx) significantly (p?<?0.05) attenuates the release of pro-inflammatory cytokines, such as TNF-α, IFN-γ, and IL-6, while its in situ produced acetyl derivative, i.e., taraxasterol acetate (TxAc), did not inhibit the LPS-induced IL-6 production at lower concentration (p?>?0.05). Surflex-Dock molecular modeling study was performed to simulate the binding capacity of compounds into the active site of the TNF-α (2AZ5), tumor protein P53 (2VUK), and NF-kappa-B (1RAM). The differential inhibition of cytokines by Tx and TxAc was further confirmed by high docking scores showing the high affinity to target proteins. Findings of the study demonstrated the comparatively greater role of Pluchea triterpene than its in situ produced acetate derivate in neuroinflammation-associated disorders.  相似文献   
25.
26.
Objective: To identify the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in patients with transthyretin (ATTR) amyloidosis.

Patients and methods: We performed a retrospective analysis of patients with biopsy-proven ATTRwt (wild-type transthyretin amyloid protein) and genopositive ATTR V122I (valine-to-isoleucine substitution at position 122 of the TTR gene) amyloidosis evaluated at the Amyloidosis Center at Boston University and Boston Medical Center between 1 January 2003 and 31 December 2016.

Results: There were a total of 226 patients with ATTRwt and ATTR V122I amyloidosis evaluated during the specified time frame with 155 and 71 patients in each cohort, respectively. Those with complete medical records, 140 patients with ATTRwt and 57 V1221 ATTRm subjects, were included in the analyses. Fifty-five patients (39%) in the ATTRwt cohort and 28 patients (49%) in the ATTR V122I cohort had an MGUS, as indicated by an abnormality in the serum-free light-chain ratio and/or serum immunofixation electrophoresis.

Conclusion: These data confirm the high prevalence of coexistent MGUS with ATTR amyloidosis in this patient population, with an MGUS rate that is higher than the general population. These findings also highlight the importance of a thorough diagnostic evaluation in patients with amyloidosis to determine the precursor protein, as the clinical course and treatment of AL (light-chain amyloid protein) and ATTR amyloidosis are distinct.  相似文献   

27.
Agriculture is a major contributor to air pollution, the largest environmental risk factor for mortality in the United States and worldwide. It is largely unknown, however, how individual foods or entire diets affect human health via poor air quality. We show how food production negatively impacts human health by increasing atmospheric fine particulate matter (PM2.5), and we identify ways to reduce these negative impacts of agriculture. We quantify the air quality–related health damages attributable to 95 agricultural commodities and 67 final food products, which encompass >99% of agricultural production in the United States. Agricultural production in the United States results in 17,900 annual air quality–related deaths, 15,900 of which are from food production. Of those, 80% are attributable to animal-based foods, both directly from animal production and indirectly from growing animal feed. On-farm interventions can reduce PM2.5-related mortality by 50%, including improved livestock waste management and fertilizer application practices that reduce emissions of ammonia, a secondary PM2.5 precursor, and improved crop and animal production practices that reduce primary PM2.5 emissions from tillage, field burning, livestock dust, and machinery. Dietary shifts toward more plant-based foods that maintain protein intake and other nutritional needs could reduce agricultural air quality–related mortality by 68 to 83%. In sum, improved livestock and fertilization practices, and dietary shifts could greatly decrease the health impacts of agriculture caused by its contribution to reduced air quality.

The health and environmental consequences of feeding the increasingly large and affluent global population are becoming increasingly apparent. These consequences have spurred interest in identifying food production practices and diets that improve human health and reduce environmental harm. Recent work has demonstrated that many of the opportunities for food producers and consumers to improve nutritional outcomes also have environmental benefits, such as reducing greenhouse gas emissions, land and water use, and eutrophication (16). It is largely unknown, however, how individual foods and diets affect air quality, even though air pollution is the largest environmental mortality risk factor in the United States and globally (7, 8), and agriculture is itself known to be a major contributor to reduced air quality (8, 9). In the United States alone, atmospheric fine particulate matter (PM2.5) from anthropogenic sources is responsible for about 100,000 premature deaths each year, one-fifth of which are linked to agriculture (10, 11).Here, we show how different foods affect human health by reducing air quality. We consider the emission of pollutants that contribute to atmospheric PM2.5, the chronic exposure to which increases the incidence of premature mortality from cardiovascular disease, cancer, and stroke (12, 13). These pollutants include directly emitted PM2.5 (primary PM2.5) and PM2.5 formed in the atmosphere (secondary PM2.5) from the precursors ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2), and nonmethane volatile organic compounds (NMVOCs). From a spatially explicit inventory of emissions of primary PM2.5 and secondary PM2.5 precursors from agricultural supply chain activities for commodities in the contiguous United States (SI Appendix, Figs. S1 and S2) (14, 15) (Materials and Methods), we estimate increases in atmospheric concentrations of total (primary + secondary) PM2.5 attributable to agricultural emissions; total PM2.5 transport, chemistry, and removal; and exposure of populations to total PM2.5 using an ensemble of three independent air quality models (1619). We describe damages attributable to 95 agricultural commodities and 67 final food products (full list in SI Appendix, Table S1), which cover >99% of US agricultural production (20).  相似文献   
28.
Tubercular liver abscess is a rare entity even in an endemic area for TB. We report here a rare case of pediatric tuberculous liver abscess, the etiology of which was established using recently introduced Cartridge based nucleic acid amplification test (CBNAAT). A 7 years old male child presented with vomiting, pain abdomen and fever. Hepatomegaly was found on examination. Ultrasound of abdomen revealed two liver abscesses in the right lobe. Patient remained symptomatic even after empirical antimicrobial therapy. On diagnostic tap Gram stained smear of the pus showed polymorphs with negative culture. CBNAAT was positive for Mycobacterial tuberculosis and sensitive to rifampicin. Subjecting difficult extrapulmonary specimens to relevant microbiological investigations along with CBNAAT and other newer methods may improve diagnosis of tuberculosis in such rare cases thus leading to an early management and decrease in morbidity.  相似文献   
29.
30.
Autologous airway epithelial cells have been used in clinical tissue‐engineered airway transplantation procedures with a view to assisting mucosal regeneration and restoring mucociliary escalator function. However, limited time is available for epithelial cell expansion due to the urgent nature of these interventions and slow epithelial regeneration has been observed in patients. Human airway epithelial cells can be expanded from small biopsies or brushings taken during bronchoscopy procedures, but the optimal mode of tissue acquisition from patients has not been investigated. Here, we compared endobronchial brushing and endobronchial biopsy samples in terms of their cell number and their ability to initiate basal epithelial stem cell cultures. We found that direct co‐culture of samples with 3T3‐J2 feeder cells in culture medium containing a Rho‐associated protein kinase inhibitor, Y‐27632, led to the selective expansion of greater numbers of basal epithelial stem cells during the critical early stages of culture than traditional techniques. Additionally, we established the benefit of initiating cell cultures from cell suspensions, either using brushing samples or through enzymatic digestion of biopsies, over explant culture. Primary epithelial cell cultures were initiated from endobronchial biopsy samples that had been cryopreserved before the initiation of cell cultures, suggesting that cryopreservation could eliminate the requirement for close proximity between the clinical facility in which biopsy samples are taken and the specialist laboratory in which epithelial cells are cultured. Overall, our results suggest ways to expedite epithelial cell preparation in future airway cell therapy or bioengineered airway transplantation procedures.  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