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   5344篇
  免费   270篇
  国内免费   22篇
耳鼻咽喉   93篇
儿科学   278篇
妇产科学   34篇
基础医学   570篇
口腔科学   120篇
临床医学   371篇
内科学   1202篇
皮肤病学   188篇
神经病学   277篇
特种医学   86篇
外科学   904篇
综合类   123篇
一般理论   1篇
预防医学   245篇
眼科学   192篇
药学   431篇
  1篇
中国医学   19篇
肿瘤学   501篇
  2024年   4篇
  2023年   40篇
  2022年   92篇
  2021年   219篇
  2020年   104篇
  2019年   144篇
  2018年   190篇
  2017年   127篇
  2016年   161篇
  2015年   181篇
  2014年   256篇
  2013年   315篇
  2012年   504篇
  2011年   517篇
  2010年   293篇
  2009年   225篇
  2008年   364篇
  2007年   342篇
  2006年   328篇
  2005年   295篇
  2004年   258篇
  2003年   244篇
  2002年   206篇
  2001年   26篇
  2000年   24篇
  1999年   32篇
  1998年   27篇
  1997年   21篇
  1996年   19篇
  1995年   6篇
  1994年   10篇
  1993年   8篇
  1992年   4篇
  1991年   5篇
  1990年   4篇
  1989年   9篇
  1988年   8篇
  1987年   3篇
  1985年   4篇
  1984年   2篇
  1982年   2篇
  1981年   3篇
  1978年   1篇
  1976年   1篇
  1970年   1篇
  1954年   1篇
  1949年   1篇
  1934年   1篇
  1930年   1篇
  1929年   1篇
排序方式: 共有5636条查询结果,搜索用时 0 毫秒
71.
72.
73.
Background : Several regions such as Zambia in sub-Saharan Africa experience very high levels of sterility. Current explanations for high levels of sterility in Zambia have focused on biological determinants and have paid little attention to the plausible effects of social determinants of sterility. Aim : This study has two objectives. The first objective is to examine the extent of sterility in Zambia during 1980 and 1990. The second objective is to assess the contribution of selected social determinants to the current levels of sterility in Zambia. Subjects and methods : Sterility among women in Zambia is calculated for two periods in 1980 and 1990 using census data. The study used parity progression ratios for the calculation of sterility rates. Selected social determinants of Zambian sterility were obtained from the Demographic Health Survey (ZDHS). Net effects of selected social determinants were examined using logistic regression. Results : High sterility levels were found in a few Zambian Provinces. During 1980 and 1990, the rates for North Western, Eastern and Western provinces remained considerably higher than for other Zambian provinces. It was found that social level variables remained strong and significant even after controlling for the effects of incidence of biological factors such as sexually transmitted diseases (STDs). Conclusions : The findings of the study support the importance of developing social policies for eradicating sterility. The argument that sterility is biological and that it is not amenable to social interventions perhaps needs revision in the light of the findings of this study.  相似文献   
74.

Objective

Because existing numeracy measures may not optimally assess ‘health numeracy’, we developed and validated the General Health Numeracy Test (GHNT).

Methods

An iterative pilot testing process produced 21 GHNT items that were administered to 205 patients along with validated measures of health literacy, objective numeracy, subjective numeracy, and medication understanding and medication adherence. We assessed the GHNT's internal consistency reliability, construct validity, and explored its predictive validity.

Results

On average, participants were 55.0 ± 13.8 years old, 64.9% female, 29.8% non-White, and 51.7% had incomes ≤$39 K with 14.4 ± 2.9 years of education. Psychometric testing produced a 6-item version (GHNT-6). The GHNT-21 and GHNT-6 had acceptable-good internal consistency reliability (KR-20 = 0.87 vs. 0.77, respectively). Both versions were positively associated with income, education, health literacy, objective numeracy, and subjective numeracy (all p < .001). Furthermore, both versions were associated with participants’ understanding of their medications and medication adherence in unadjusted analyses, but only the GHNT-21 was associated with medication understanding in adjusted analyses.

Conclusions

The GHNT-21 and GHNT-6 are reliable and valid tools for assessing health numeracy.

Practice implications

Brief, reliable, and valid assessments of health numeracy can assess a patient's numeracy status, and may ultimately help providers and educators tailor education to patients.  相似文献   
75.
White mold and stem rot is a common disease of Phaseolus vulgaris caused by Sclerotinia sclerotiorum. Biological control is a promising alternative for the control of this disease. In the present study, two Trichoderma spp., T. erinaceum and T. viride, and the consortium of both were evaluated as biocontrol agents against sclerotinia stem rot disease. The results revealed that T. erinaceum (NAIMCC-F-02171) and T. viride (NAIMCC-F-02500) when applied alone, significantly suppressed the infection rate of S. sclerotiorum and increased the rate of survival of plants by 74.5%. On the contrary, the combination of both the Trichoderma spp. was found to be more effective in reducing stem rot by 57.2% and increasing the survival of plants by 87.5% when compared to the individual Trichoderma applications. Further, the exogenous supplementation of Trichoderma activated antioxidative machineries, such as peroxidase, polyphenol oxidase, superoxide dismutase, catalase, and ascorbic acid in the plant. Besides, hydrogen peroxide and superoxide-free radical accumulation were also found to be reduced when T. erinaceum and T. viride were used either individually or in combination under the pathogen-challenged condition. Additionally, the photopigments in the bioprimed plants were markedly increased. Moreover, the combined inoculation of the two isolates yielded the highest records of growth parameters (root weight, shoot length, and leaf weight) compared with individual inoculation. Therefore, based on the above results, it was concluded that the combination of T. erinaceum and T. viride can be effectively used as an alternative to control white mold and stem rot caused by S. sclerotiorum.  相似文献   
76.
77.
Metal-free organic polymer photocatalysts have attracted dramatic attention in the field of visible light-induced hydrogen evolution reaction (HER). Herein, we showed a polymeric O-linked heptazine polymer (OLHP) decorated with S, N co-doped graphene quantum dots (S,N-GQDs) as a photosensitizer to generate hydrogen upon quantum dot sensitization. Both of these heptazine-based systems show effective photosensitization with strong π–π interactions and enhanced photocatalytic H2 generation (24 times) as metal-free systems. Electrochemical impedance and optical measurements show effective charge transfer kinetics with decreased charge recombination, which is responsible for the enhanced photocatalytic activity. As a result, a significant high apparent quantum yield (AQY) with highest value of 10.2% was obtained for our photocatalyst OLHP/S,N-GQD10.

A polymeric O-linked heptazine polymer (OLHP) decorated with S, N co-doped graphene quantum dots (S,N-GQDs) as a photosensitizer to utilize visible light (λ > 420 nm) for hydrogen generation.  相似文献   
78.
Kim  Dohyun  Lee  Hyunjung  Chung  Minsun  Kim  Sunil  Song  Minju  Kim  Euiseong 《Clinical oral investigations》2020,24(1):247-255
Clinical Oral Investigations - The purpose of this retrospective study was to evaluate and compare the effects of fast- and slow-setting calcium silicate–based materials (CSMs) used for...  相似文献   
79.
80.
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