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   384篇
  免费   43篇
  国内免费   2篇
耳鼻咽喉   9篇
儿科学   19篇
基础医学   84篇
口腔科学   10篇
临床医学   27篇
内科学   55篇
皮肤病学   1篇
神经病学   29篇
特种医学   5篇
外科学   41篇
综合类   10篇
预防医学   62篇
眼科学   4篇
药学   26篇
中国医学   1篇
肿瘤学   46篇
  2023年   2篇
  2022年   5篇
  2021年   11篇
  2020年   11篇
  2019年   10篇
  2018年   11篇
  2017年   3篇
  2016年   5篇
  2015年   11篇
  2014年   15篇
  2013年   15篇
  2012年   30篇
  2011年   27篇
  2010年   9篇
  2009年   10篇
  2008年   23篇
  2007年   25篇
  2006年   20篇
  2005年   27篇
  2004年   21篇
  2003年   21篇
  2002年   19篇
  2001年   5篇
  2000年   7篇
  1999年   12篇
  1998年   6篇
  1997年   2篇
  1996年   5篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   5篇
  1989年   7篇
  1988年   3篇
  1987年   3篇
  1985年   4篇
  1984年   2篇
  1981年   1篇
  1980年   4篇
  1979年   8篇
  1978年   4篇
  1977年   2篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1971年   2篇
  1970年   4篇
排序方式: 共有429条查询结果,搜索用时 15 毫秒
31.
Mural endocarditis that involves the left atrial wall is rare. We report on the transesophageal findings in a patient with left atrial mural endocarditis and discuss its recognition, complications, and treatment.  相似文献   
32.
A new series of N-substituted imide derivatives have been synthesized by treating phthalic anhydride, naphthalic anhydride and their substituted derivatives with 2-hydrazino-1-imidazoline hydrobromide, various para-substituted aryl amines, aminoglutethimide and 2,4-dinitrophenyl hydrazine. Compounds 9, 10, 12, 18, 19, 23, 24 and 34-36 have been selected and screened for antineoplastic activity by National Cancer Institute, Bethesda, USA. Some newer aminoglutethimide derivatives 37-39 have also been prepared in order to study the effect of N-substitution on its pharmacological profile for the treatment of carcinoma. These compounds (37-39) have exhibited weak inhibition of human placental aromatase as compared to aminoglutethimide.  相似文献   
33.
Objective. To describe criteria for evaluating faculty scholarship within the promotion and tenure guidance documents of US schools and colleges of pharmacy.Methods. Promotion and tenure documents were obtained from the websites of US pharmacy schools or requested via electronic mail, and institutional characteristics were collected from publicly available online data. A qualitative content analysis was conducted to systematically catalogue document characteristics and criteria for promotion and tenure.Results. Promotion and tenure guidance documents from 121 (85%) of 142 pharmacy schools were analyzed. Institutions were 55% public and equally distributed across Carnegie institutional classifications as well as geographic and extramural funding stratifications. Publications (94%) and grants and contracts (87%) were the most frequently included criteria for faculty advancement. More than 50% of schools recognized the criteria within promotion and tenure guidance documents but did not explicitly require faculty to achieve them before receiving promotion and/or tenure. For institutions that required publications for advancement, the most frequently required criterion was publication in peer-reviewed journals (47%). Few schools (22%) documented a specific number of required publications.Conclusion. This analysis provides a comprehensive review of scholarship criteria in academic pharmacy promotion and tenure guidance documents. There was wide variability among scholarship criteria, and documents often lacked specific language defining scholarship requirements. As a result, faculty may find the documents less helpful for self-assessment and preparation toward promotion and/or tenure. These benchmark data can assist pharmacy faculty and administrators in developing and revising promotion and tenure guidance documents to include clear criteria and better align with peer institutions.  相似文献   
34.
To determine the safety and immunogenicity of an inactivated hepatitis A vaccine, 56 healthy adult volunteers were randomly assigned to receive an intramuscular injection of 6.3, 12.5 or 25 ng of inactivated hepatitis A vaccine or placebo at 0, 2 or 4, and 24 weeks. Adverse reactions occurred with similar frequency in vaccine and placebo recipients and consisted primarily of pain or tenderness at the injection site. By 4 weeks after a single 6.3, 12.5 or 25 ng injection, seven, nine and ten out of ten vaccinees, respectively, had antibody detectable by a HAV AB assay modified to increase its sensitivity tenfold. All vaccinees had antibodies detectable by this assay within 2 weeks of their second inoculation. Geometric mean antibody levels increased with higher doses of vaccine (p = 0.05). Neutralizing antibody was detected within 4 weeks of a single inoculation in all vaccinees. Neutralizing antibody was detected after the third inoculation at dilutions of greater than or equal to 1:2048 in all 12.5 and 25 ng vaccinees. All 19 vaccinees tested at 24 months still had HAV antibodies detectable by a modified HAV AB assay. This inactivated hepatitis A vaccine appears to be well tolerated and immunogenic at doses of 6.3-25 ng. The choice of dose and vaccination schedule may depend on the rapidity with which seroconversion is desired.  相似文献   
35.
Objectives. To identify factors associated with academic help-seeking behavior among student pharmacists at a public university.Methods. Semi-structured focus group interviews were conducted to explore in depth perceptions of facilitators of and barriers to the help-seeking behavior and academic achievement of student pharmacists who had received a D or F grade in any year. A 4-part survey instrument was developed and administered to all student pharmacists and included sections for (1) attitudes and academic help-seeking behavior, (2) health status, (3) demographics, and (4) open comments. A structural equation modeling approach was used to assess relationships among domains of interest.Results. Three student focus groups noted that helpfulness of faculty members and school administrators were 2 prominent facilitators of help-seeking behavior and academic achievement. Diminished quality of life caused by stress and depression was the primary barrier to help-seeking and achievement. Three hundred four (68.6%) student pharmacists completed the survey instrument. Academic help-seeking behavior was influenced mostly by perceived academic competence and perceived faculty helpfulness. In contrast, ambivalence and perception of help-seeking as threatening were 2 factors that were negatively associated with academic help-seeking behavior.Conclusions. Academic help-seeking behavior was positively related to greater perceived academic competence and positive relationships among student pharmacists and faculty members.  相似文献   
36.
The possible role of ultraviolet light in the formation of cataract is not well understood. In this study, guinea pigs were exposed to a chronic, low level of UVA light (0.5 mWcm(-2), 340-410 nm wavelength, peak at 365 nm) for 4-5 months. It is known that the lens of the guinea pig possesses unusually high levels of the UVA chromophore NADPH. In a preliminary analysis, it was found that isolated guinea pig corneas transmitted 70-90% of 340-400 nm light, and that UVA radiation was able to penetrate deep into the nucleus of the guinea pig lens, where it was absorbed. Exposure of guinea pigs to UVA in vivo produced a 60% inactivation of lens epithelial catalase; however, analysis by transmission electron microscopy (TEM) showed no apparent morphological effects on either the lens epithelium or the cortex. A number of UVA-induced effects were found in the nucleus of the guinea pig lens, but were observed either not at all or to a lesser extent in the cortex. The effects included an increase in light scattering (two-fold; slit-lamp examination), distention of intercellular spaces (TEM), an increase in lipid peroxidation (30-35%; infrared spectroscopy), a decrease in GSH level (30%), an increase in protein-thiol mixed disulfide levels (80%), loss of water-soluble protein (20%), an increase in the amount of protein disulfide (two-fold; two-dimensional diagonal electrophoresis), degradation of MIP26 (15%) and loss of cytoskeletal proteins including actin, alpha- and beta- tubulin, vimentin and alpha-actinin (60-100%). The results indicate that a 4-5 month exposure of guinea pigs to a biologically relevant level of UVA light produces deleterious effects on the central region of the lenses of the animals. UVA radiation, coupled presumably with the photoreactive UVA chromophore NADPH and trace amounts of O(2) present in the lens nucleus, produced significant levels of oxidized products in the nuclear region over a five month period. The data demonstrate the potentially harmful nature of UVA light with respect to the lens, and highlight the importance of investigating a possible role for this type of radiation in the formation of human cataract.  相似文献   
37.
38.
This study shows the benefit of spoligotyping coupled to mycobacterial interspersed repetitive-unit (MIRU) typing to pinpoint circulating Mycobacterium tuberculosis genotypes in Guadeloupe, Martinique, and French Guiana. We hereby propose reduced 4-locus and 6-locus subsets for LAM and Haarlem lineage strains that predominate in South America and the Caribbean, retaining 99.35% and 99.64% of the total discriminatory power of the 12-locus scheme, respectively.  相似文献   
39.
The use of the 15N label for agronomic research involving nitrogen (N) cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contribute methodologically to the design and development of 15N labeled fertilizer experiments, using as an example a coffee crop fertilized with 15N labeled ammonium sulfate, which was followed for two years. The N of the plant derived from the fertilizer was studied in the different parts of the coffee plant in order to evaluate its distribution within the plant and the agronomic efficiency of the fertilizer application practice. An enrichment of the fertilizer-N of the order of 2% 15N abundance was sufficient to study N absorption rates and to establish fertilizer-N balances after one and two years of coffee cropping. The main source of errors in the estimated values lies in the inherent variability among field replicates and not in the measurements of N contents and 15N enrichments of plant material by mass-spectrometry.  相似文献   
40.
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