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   2274篇
  免费   139篇
  国内免费   20篇
耳鼻咽喉   24篇
儿科学   185篇
妇产科学   14篇
基础医学   223篇
口腔科学   71篇
临床医学   199篇
内科学   611篇
皮肤病学   37篇
神经病学   123篇
特种医学   81篇
外科学   327篇
综合类   41篇
预防医学   58篇
眼科学   51篇
药学   216篇
中国医学   18篇
肿瘤学   154篇
  2023年   19篇
  2022年   25篇
  2021年   84篇
  2020年   48篇
  2019年   63篇
  2018年   83篇
  2017年   61篇
  2016年   66篇
  2015年   58篇
  2014年   101篇
  2013年   133篇
  2012年   192篇
  2011年   192篇
  2010年   91篇
  2009年   81篇
  2008年   156篇
  2007年   148篇
  2006年   139篇
  2005年   126篇
  2004年   103篇
  2003年   80篇
  2002年   69篇
  2001年   24篇
  2000年   29篇
  1999年   41篇
  1998年   16篇
  1997年   9篇
  1996年   9篇
  1995年   7篇
  1994年   5篇
  1993年   5篇
  1992年   15篇
  1991年   16篇
  1990年   11篇
  1989年   8篇
  1988年   10篇
  1987年   8篇
  1986年   9篇
  1985年   8篇
  1984年   7篇
  1983年   6篇
  1981年   5篇
  1980年   6篇
  1979年   4篇
  1978年   8篇
  1975年   8篇
  1973年   9篇
  1968年   5篇
  1967年   6篇
  1966年   3篇
排序方式: 共有2433条查询结果,搜索用时 15 毫秒
91.
Invasive Salmonella infections for which improved or new vaccines are being developed include enteric fever caused by Salmonella enterica serovars Typhi, Paratyphi A, and Paratyphi B and sepsis and meningitis in young children in sub-Saharan Africa caused by nontyphoidal Salmonella (NTS) serovars, particularly S. enterica serovars Typhimurium and Enteritidis. Assays are needed to measure functional antibodies elicited by the new vaccines to assess their immunogenicities and potential protective capacities. We developed in vitro assays to quantify serum bactericidal antibody (SBA) activity induced by S. Typhi, S. Paratyphi A, S. Typhimurium, and S. Enteritidis vaccines in preclinical studies. Complement from various sources was tested in assays designed to measure antibody-dependent complement-mediated killing. Serum from rabbits 3 to 4 weeks of age provided the best complement source compared to serum from pigs, goats, horses, bovine calves, or rabbits 8 to 12 weeks of age. For S. Enteritidis, S. Typhimurium, and S. Typhi SBA assays to be effective, bacteria had to be harvested at log phase. In contrast, S. Paratyphi A was equally susceptible to killing whether it was grown to the stationary or log phase. The typhoidal serovars were more susceptible to complement-mediated killing than were the nontyphoidal serovars. Lastly, the SBA endpoint titers correlated with serum IgG anti-lipopolysaccharide (LPS) titers in mice immunized with mucosally administered S. Typhimurium, S. Enteritidis, and S. Paratyphi A but not S. Typhi live attenuated vaccines. The SBA assay described here is a useful tool for measuring functional antibodies elicited by Salmonella vaccine candidates.  相似文献   
92.

Objectives

Study includes 20 patients with diagnosis of fascial space infections of odontogenic origin to assess efficacy of serum prealbumin and CRP levels as monitoring tools for determining severity of infections, nutritional status, hospital stay and efficacy of treatment.

Methods

Blood samples taken on day 0, 4, and 8 for measuring serum levels of markers. Simultaneously clinical parameters like swelling size, pain etc., were also recorded on day 0, 4, and 8 and appropriate treatment given to each patient. Correlation between markers and parameters was found using regression and paired t test.

Results

Statistical analysis found strong correlation between laboratory values of markers and parameters used to measure severity of infection also. Prealbumin and crp are significant markers for hospital stay (p < 0.01). Prealbumin also found to be a sensitive indicator of nutritional status (p < 0.001).

Interpretation and Conclusion

Prospective analysis indicates prealbumin and crp are effective markers for determining severity of infection, treatment efficacy and hospital stay. Prealbumin is also sensitive marker for nutritional status. Duration of antibiotic usage, intensive unit care, use of nutritional supplements becomes more rationale. Markers also make treatment cost effective and help protecting patients from side effects of excess drug usage.  相似文献   
93.
Recent estimates for the global brain health supplement category, i.e. nootropic market size, will grow to nearly $5.8 billion by 2023. Overall, nearly one-quarter (23%) of adults currently take a supplement to maintain or improve brain health or delay and reverse dementia. Not surprisingly, the use of such supplements increases with age - more than one-third of the oldest generation (ages 74 and older) takes a supplement for brain health. This widespread use is being driven by a strong desire both in the younger and older generations to enhance cognitive performance and achieve healthy aging. The most prevalent botanicals currently dominating the nootropic marketplace include Gingko biloba, American ginseng, and Bacopa monnieri. However, other botanicals that affect stress, focus, attention, and sleep have also been procured by dietary supplement companies developing products for improving both, short and long-term brain health. This review focuses on efficacy data for neuroactive botanicals targeted at improving cognitive function, stress reduction, memory, mood, attention, concentration, focus, and alertness, including Bacopa monnieri, Ginkgo biloba, Holy basil, American ginseng, Gotu kola, Lemon balm, Common and Spanish sages and spearmint. Botanicals are discussed in terms of available clinical efficacy data and current safety profiles. Data gaps are highlighted for both efficacy and safety to bring attention to unmet needs and future research.  相似文献   
94.
Lead-free Na1/2Bi1/2TiO3-BaTiO3 (NBT-BT) has gained revived interest due to its exceptionally good high power properties in comparison to commercial lead-based piezoelectrics. Recently, Zn-modified NBT-BT-based materials as solid solution and composites have been reported to exhibit enhanced depolarization temperatures and a high mechanical quality factor. In this work, the pyroelectric properties of Zn-doped NBT-6mole%BT and NBT-9mole%BT ceramics are investigated. The doped compositions of NBT-6BT and NBT-9BT feature a relatively stable pyroelectric property in a wide temperature range of ~37 K (300–330 K) and 80 K (300–380 K), respectively. A threefold increase in detector figure of merit is noted for 0.01 mole Zn-doped NBT-6mole% BT at room temperature in comparison to undoped NBT-6mole%BT and this increase is higher than those of major lead-free materials. A broad range of the temperature-independent behavior for the figures of merit was noted (303–380 K) for Zn-doped NBT-6mole% BT, which is 30 K higher than the undoped material. The large pyroelectric figures of merit and good temperature stability renders Zn-doped NBT-BT an ideal candidate for pyroelectric detector and energy harvesting applications.  相似文献   
95.
Indian Journal of Pediatrics - Youth and adolescents are the priority population to target the interventions as risky behaviors persist and they contribute to almost half of the new Human...  相似文献   
96.
Journal of Neuro-Oncology - To report clinical outcomes of salvage re-irradiation (re-RT) in recurrent/progressive ependymoma. Medical records of patients treated with curative-intent re-RT as...  相似文献   
97.
Journal of Neuro-Oncology - MYC-driven medulloblastomas are highly aggressive childhood tumors with dismal outcomes and a lack of new treatment paradigms. We identified that targeting replication...  相似文献   
98.
The purpose of fabric masks in the prevention of the spread of COVID-19 often requires that the masks be worn for extended periods without removal. The management of the conditions in the micro-climate inside the masks is important to keep the wearer comfortable and enhance user compliance. In this study, the effect of mask design and fabric type on the micro-climate was investigated using thermocron iButtons to record the temperature and humidity inside the masks. It was found that the mask style, and its effect on the amount of air incorporated in the micro-climate, had a significant influence on the factors that determine the temperature and humidity levels. In the shaped masks, the impact of the mask design on the results was stronger than the effect of fabric type. In the folded masks that fit snugly around the face, the effect of fabric type was significant, and both fibre composition and fabric structure contributed to the differences in the performance of the three fabrics tested. In the case of the masks with an inserted filter, a significant amount of trapped still air in the fabric layers and the increased mask stiffness had the strongest effect on the temperature and humidity inside the masks. Significant differences were also found in the temperatures recorded in the different time segments, highlighting the importance of conducting comfort evaluations over a long enough time to prevent false interpretations. The results of this study emphasize the importance of considering all the components of mask design, namely style, fibre type, and fabric structure, in the development of masks to enhance user compliance.  相似文献   
99.
100.
Insulin inhibits platelet aggregation through nitric oxide synthesis by stimulating platelet insulin activated nitric oxide synthase. Impaired platelet insulin activated nitric oxide synthase in acute myocardial infarction (AMI) patients had been reported and thus our aim was to identify and isolate the factors impairing insulin activated nitric oxide in acute myocardial infarction patients’ plasma and study its effect on platelets aggregation in vitro. The insulin activated nitric oxide synthase inhibitor was identified as a protein and was purified from the plasma of AMI subjects using DEAE cellulose and Sephadex G-50 column, molecular weight determined by SDS-PAGE, nitric oxide quantified by methaemoglobin method, inhibitor protein quantified in plasma by immunoblot and ELISA, platelet aggregation studies done using an aggregometer, thromboxane-A2 in the platelets determined by radioimmunoassay, 125I-insulin radioligand binding studies done using normal subject platelets. The purified nitric oxide synthase inhibitor protein was ~66 kDa, concentration in AMI subjects’ plasma varied from 114 to 9,090 μM and was undetected in normal subjects’ plasma. The inhibitor protein competes with insulin for insulin receptor binding sites. The Incubation of the normal subject PRP with 5.0 μM inhibitor for 30 min followed by 0.4 μM ADP addition caused platelet aggregation in vitro, 130 μM aspirin or 400 μU insulin/ml addition was able to abrogate 0.4 μM ADP induced platelet aggregation even in the presence of 5.0 μM inhibitor. A potent inhibitory protein against insulin activated nitric oxide synthase in platelets appears in circulation of AMI subjects impairing nitric oxide production, potentiating ADP induced platelet aggregation and increasing the thromboxane-A2 level in platelets.  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