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   425篇
  免费   45篇
  国内免费   2篇
耳鼻咽喉   2篇
儿科学   15篇
妇产科学   7篇
基础医学   45篇
口腔科学   20篇
临床医学   54篇
内科学   88篇
皮肤病学   18篇
神经病学   38篇
特种医学   39篇
外科学   44篇
综合类   11篇
预防医学   16篇
眼科学   4篇
药学   46篇
肿瘤学   25篇
  2022年   6篇
  2021年   8篇
  2020年   6篇
  2019年   5篇
  2018年   6篇
  2017年   4篇
  2016年   4篇
  2015年   12篇
  2014年   9篇
  2013年   16篇
  2012年   16篇
  2011年   13篇
  2010年   12篇
  2009年   5篇
  2008年   18篇
  2007年   15篇
  2006年   15篇
  2005年   19篇
  2004年   11篇
  2003年   11篇
  2002年   14篇
  2001年   12篇
  2000年   8篇
  1999年   10篇
  1998年   8篇
  1997年   7篇
  1996年   12篇
  1995年   7篇
  1994年   4篇
  1993年   11篇
  1992年   10篇
  1991年   5篇
  1990年   9篇
  1989年   15篇
  1988年   15篇
  1987年   8篇
  1985年   9篇
  1984年   11篇
  1983年   6篇
  1982年   5篇
  1980年   7篇
  1979年   4篇
  1978年   6篇
  1977年   6篇
  1976年   7篇
  1975年   4篇
  1974年   5篇
  1969年   3篇
  1967年   6篇
  1941年   3篇
排序方式: 共有472条查询结果,搜索用时 109 毫秒
1.
2.
BACKGROUND: The risk of hospitalization for asthma caused by outdoor aeroallergens is largely unknown. OBJECTIVE: The objective of this study was to determine the association between changes in outdoor aeroallergens and hospitalizations for asthma from the Pacific coast to the Atlantic coast of Canada. METHODS: A daily time series analysis was done to test the association between daily changes in aeroallergens and daily changes in hospitalizations for asthma during a 7-year period between 1993 and 2000 in 10 of the largest cities in Canada. Results were adjusted for long-term trends, day of the week, climate, and air pollution. RESULTS: A daily increase, equivalent to the mean value of each allergen, was associated with the following percentage increase in asthma hospitalizations: 3.3% (95% CI, 2.3 to 4.1) for basidiomycetes, 3.1% (95% CI, 2.8 to 5.7) for ascomycetes, 3.2% (95% CI, 1.6 to 4.8) for deuteromycetes, 3.0% (95% CI, 1.1 to 4.9) for weeds, 2.9% (95% CI, 0.9 to 5.0) for trees, and 2.0% (95% CI, 1.1 to 2.8) for grasses. After accounting for the independent effects of trees and ozone, the combination of the 2 was associated with an additional 0.22% increase in admissions averaged across cities (P <.05). CONCLUSION: These findings provide evidence for the hypothesis that aeroallergens are an important cause of severe asthma morbidity across Canada, and in some situations there might be a modest synergistic adverse effect of ozone and aeroallergens combined.  相似文献   
3.
目的 了解医学生对标准化病人(SP)应用于临床医学专业执业医师技能考核的认知及满意度评价情况,为加强医学人才培养、推动安徽省医学教育改革提供参考依据。方法 2021年5月以问卷调查的方式收集546名参加安徽省某高校2021年临床执业医师技能考核的学生对SP认知情况及满意度评价情况,同时开展临床执业医师技能考核,收集学生考核通过情况。采用χ2检验对SP应用于临床技能考核的认知情况及满意度评价情况进行分析。结果 546名医学生的临床执业医师技能考核合格率为84.80%。调查对象知晓SP教学或考核的比例为88.64%,接受过SP教学或考核的比例为17.77%。调查对象对SP临床技能考核的满意率为89.38%,五个层面的满意率从高到低依次为剧本内容(94.32%)、场所设施(93.77%)、时间安排(89.93%)、试题难度(88.64%)、角色表现(85.35%)。不同学制、不同SP临床技能考核通过情况的调查对象在SP应用于临床专业执业医师技能考核认知情况及满意度评价方面存在差异(P<0.05)。结论 SP临床技能考核的应用情况和满意度评价情况需进一步提升,建议卫生教育主管部门明确使用...  相似文献   
4.
Patchy connections were traced in the visual and auditory cortexof the echidna (Tachyglossus aculeatus). Labeled neurons andclusters of axon collaterals were distributed in regular arraysafter the application of a small crystal (100–300 µmdiameter) of the carbocyanine dye Dil (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocart)ocyaninepar-chlorate) into the upper cortical layers. In general, theanterograde and retrograde labels were in register, but whereasthe anterograde label was distributed throughout all six layers,the retrogradely filled neurons were absent from layer 1 andthe highest density of labeled cells was in layers 5 and 6.The cells contained within the patches were all pyramidal orpyramid-like and contained long spines on their dendrites. Therefore,despite their unusual location within the lateral posteriorcortex, the internal structure of the echidna visual and auditorycortices resembled that of eutherian mammals in containing aregular columnar array of connections that may represent thecorti-cocortical projections.  相似文献   
5.
Summary A series of 96 diarylamidine (and diarylimidazoline) derivatives were evaluated for their inhibitory effects on the growth and DNA synthesis of murine leukemia L1210 cells. The amidino- and imidazolino-substituted aryl moieties of the compounds consisted of phenyl, indole, indene, benzofuran, benzo[b]thiophene or benzimidazole. Several of these compounds were found to inhibit L1210 cell proliferation with an ID50 (50% inhibitory dose) of 1 g/ml or lower. Structure-function analysis revealed that the antitumor cell activity of the diarylamidines depended on the planarity of the molecule, the presence of amidino- (or, preferably, imidazolino-) groups on both aryl moieties, the nature of the bridge connecting the two aryl moieties (preferably no bridge at all, phenoxy or ethene) and, finally, the nature of the aryl moieties (preferably, benzofuran or benzo[b]thiophene). Hence, compound 20 (6-(2-imidazolin-2-yl)-2-[4-(2-imidazolin-2-yl)phenyl] benzo[b]thiophene) emerged as the most potent inhibitor of L1210 cell growth (ID50: 0.21 g/ml). Its inhibitory potency was similar to that of the well-known trypanocidal drug ethidium bromide (compound 98). For all diarylamidine derivatives taken together, some correlation (r = 0.612) was noted between the log ID50 for L1210 cell proliferation and the log ID50 for L1210 cell DNA synthesis (as monitored by [methyl 3H]dThd incorporation). These findings suggest that the inhibitory effects of the diarylamidines on L1210 cell proliferation may at least partially reside in an inhibition of DNA synthesis. Compound 41 (2,2-vinylenedi-1-benzofuran-5-carboxamidine), that exhibited a potent antitumor activity in vitro (ID50: 1.5 g/ml), was further evaluated for its antitumor efficacy in vivo and found to increase the median survival time of L1210 cell-inoculated BDF1 mice up to 204%, if administered at a dose of 200 mg/kg.  相似文献   
6.
对发展中国家改善用药的10点建议   总被引:2,自引:0,他引:2  
唐镜波  龚丽娴 《中国药师》2005,8(10):865-868
WHO建议改善药品管理的工作要在国家药物政策保障之下.在许多国家,执行国家药物政策的机制是实施国家基本药物计划,其要点是强调公共领域的药品选择、采购、流通与使用的合理性.不适当的处方使医疗质量降低并导致资源浪费.本文以探讨在国家药物政策范畴内鼓励更合理地使用药品的问题为重点,在已有证据的基础上,详细阐明基本药物计划内容中的合理用药问题.本文评述了在发展中国家改善用药状况的有效策略及最新知识,并为决策者与管理者提出达到改善用药目标的建议.  相似文献   
7.
Differences in survival by histologic type of pancreatic cancer.   总被引:3,自引:0,他引:3  
OBJECTIVE: Although pancreatic cancer has an extremely high case fatality rate, little is known about differences in mortality by histologic types. We examined median survival and risk of mortality for endocrine pancreatic tumors and two types of exocrine tumors, adenocarcinomas, and mucinous tumors. METHOD: This analysis included 35,276 pancreatic cancer cases reported to the nine population-based cancer registries participating in the Surveillance, Epidemiology, and End Results program from 1973 to 2000. Survival among cases with pancreatic adenocarcinomas, mucinous tumors, and endocrine tumors were compared using Kaplan-Meier plots. Comparative risks of mortality were evaluated using multivariate adjusted Cox regression models. RESULTS: Endocrine pancreatic cancer cases had a median survival of 27 months compared with a median survival of 4 months for adenocarcinoma and mucinous tumor cases. Compared with adenocarcinoma cases, endocrine tumor cases had a 0.28-fold lower risk of mortality [95% confidence interval (95% CI), 0.26-0.30], and mucinous tumor cases had a 0.88-fold lower risk (95% CI, 0.84-0.91). These results were similar for men and women. Within histologic types, advanced tumor stage, older diagnosis age, surgery, and Black race were associated with increased risks of mortality, whereas female sex and more recent year of diagnosis were associated with decreased risks. CONCLUSION: This study confirms the clinical observation that patients with endocrine pancreatic cancer survive longer than patients with exocrine tumors. A better understanding of these differences could contribute to identifying the underlying causes of pancreatic cancer and to improving survival rates across all histologic types.  相似文献   
8.
9.
10.
Alteration of the TAL1 locus is the most common nonrandom genetic defect in childhood T-cell acute lymphoblastic leukemia (T-ALL). To determine if rearrangements of the TAL1 proto-oncogene confer a distinct leukemic phenotype, we studied leukemic peripheral blood or bone marrow samples from 182 children with newly diagnosed T-ALL enrolled on Pediatric Oncology Group treatment protocols. Forty-eight (26%) of the samples had a local rearrangement of the TAL1 locus. Demographic and clinical features were compared for patient subgroups with and without TAL1 rearrangements. The only clinical correlates that were significantly associated with TAL1 gene rearrangements were higher white blood cell count (P = .017) and higher hemoglobin (P = .007) at diagnosis. Immunophenotypically, samples with altered TAL1 were more likely to be CD2+ (P = .001) and lack CD10 (cALLa) expression (P = .007) than those without the rearrangement. There was a trend toward improved event-free survival (EFS) in patients with TAL1 rearrangements (4-year EFS was 44% +/- 7% for patients without the rearrangements v 59% +/- 11% for those with rearrangements), but the difference was not significant (P = .34). The role of TAL1 in leukemogenesis has yet to be clearly defined, and the prognostic significance of TAL1 gene rearrangements in T-ALL deserves further study.  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