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   1060篇
  免费   114篇
  国内免费   22篇
耳鼻咽喉   3篇
儿科学   8篇
妇产科学   18篇
基础医学   108篇
口腔科学   24篇
临床医学   58篇
内科学   147篇
皮肤病学   78篇
神经病学   28篇
特种医学   96篇
外科学   30篇
综合类   93篇
预防医学   185篇
眼科学   14篇
药学   150篇
中国医学   103篇
肿瘤学   53篇
  2023年   13篇
  2022年   36篇
  2021年   58篇
  2020年   32篇
  2019年   49篇
  2018年   40篇
  2017年   50篇
  2016年   41篇
  2015年   36篇
  2014年   48篇
  2013年   98篇
  2012年   49篇
  2011年   58篇
  2010年   53篇
  2009年   57篇
  2008年   49篇
  2007年   57篇
  2006年   50篇
  2005年   46篇
  2004年   25篇
  2003年   34篇
  2002年   32篇
  2001年   19篇
  2000年   10篇
  1999年   12篇
  1998年   18篇
  1997年   19篇
  1996年   9篇
  1995年   10篇
  1994年   10篇
  1993年   8篇
  1992年   11篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   2篇
  1987年   7篇
  1986年   5篇
  1985年   6篇
  1984年   6篇
  1983年   2篇
  1982年   3篇
  1979年   1篇
  1978年   2篇
  1977年   3篇
  1975年   2篇
  1973年   1篇
排序方式: 共有1196条查询结果,搜索用时 15 毫秒
1.
2.
Cytochemical analysis of leukemic blasts from 46 patients with acute myeloblastic M2 leukemia (according to the FAB classification) was performed before and after cytostatic therapy, and compared with findings obtained in 20 age- and sex-matched control subjects. Cytochemical findings for myeloperoxidase (MPO), Sudan black B, acid phosphatase and alpha-naphthyl-acetate esterase (ANAE) were related to the achievement of the first complete remission (CR),i.e. data were compared after the patients had been divided into CR and non-CR groups. The analysis clearly showed that a high proportion of myeloperoxidase- and, to a lesser extent, Sudan black B-positive blasts before treatment may have constituted a significantly unfavourable prognostic factor.  相似文献   
3.
BACKGROUND: Recent hospital and cancer registry data show increasing prostate cancer incidence in Nigeria, which was previously regarded as a low incidence region. This study investigates the prevalence of prostate cancer risk in a previously unscreened cohort of rural Nigerians. METHODS: Rural Nigerian men, 40 years and older, were screened by serum prostate-specific antigen (PSA) and digital rectal examination (DRE) and those with PSA >/= 4 ng/mL and/or abnormal DRE were referred for prostate biopsy. RESULTS: Of 200 consecutive men invited, 151 (75.5%) presented for screening, the mean age was 56.45 + 15.1 and 95 (61.6%) were >/= 50 years of age. Of the 140 who consented to a blood test, PSA correlated with age (r = 0.3, P < 0.01), 14 (10.0%) had abnormal PSA >/= 4 ng/mL, increasing from 3 (3.6%) in men < 60 years to 4 (50%) in men >/= 80 years. The rate was 13 (15.7%) for men >/= 50 years and there was no evidence of increased incidence of prostatitis in the community. Mean (median) PSA in ng/mL increased from 1.17 (0.60) in the youngest to 13.75 (4.45) in the oldest cohort. Of those who accepted DRE, 38 (29.0%) had an enlarged prostate, including two who had nodular prostate, one-third with symptoms, increasing from 4 (5.4%) in those < 50 years to 6 (75.0%) in men >/= 80 years. The proportion of men with PSA >/= 4 ng/mL among those with enlarged vs normal prostate is 27.0 to 3.4%, P < 0.001, and the pattern was similar for men >/= 60 years and those < 60 years of age. The 40 (32.0%) men referred for prostate biopsy defaulted mainly because they did not fully understand the need for further investigation because they were symptom free or afraid of the possible side-effects of the procedure or diagnosis of cancer. CONCLUSION: The proportion of men with PSA >/= 4 ng/mL is comparable to that of previously unscreened populations with high incidence of prostate cancer such as African-American men. A larger study is required to confirm these findings and intensify efforts to determine the prostate cancer detection rate by biopsy in this population. A prostate cancer awareness and education campaign will be useful in this community.  相似文献   
4.
研究了LDPE/CPE/炭黑三相复合导电体系的导性能和电流-电压特性。实验结果表明复合体系具有明显的导电渗滤效应,在共混比LDPE/CPE>50/50时,导电性能随CPE含量增加而显著提高,这主要是由于炭黑粒子在LDPE和CPE两组分分中的分布不均匀性所致。  相似文献   
5.
Hospital discharge data from New Jersey were used to identify cases of asbestosis for the 8 years 1979-1986. Multiple admissions were deleted so that each individual was counted once at the time of his/her first hospitalization with an asbestosis diagnosis. White males had the highest age-adjusted average annual discharge rate of 19.3 cases/100,000 population, followed by black males (12.3 cases/100,000) and white females (1.2 cases/100,000). The discharge rate was positively associated with age in each race/sex category. The relationship between rates for black males and white males depended on age: under 65 years, the rates were almost equal, and at 65 years and older, the white rates were nearly twice the black rates. There were two areas of the state where the rates were highest: the north-central and southwest regions. These two areas represent manufacturing and shipbuilding applications of asbestos, respectively. During the years 1979-1986, the annual percentage increase in asbestosis rates was 20% for white males, 17% for black males, and 8% for white females. Continued surveillance will reveal when the rates for asbestosis stop increasing.  相似文献   
6.
Fluid Flow through Filtering Appendages of Insects   总被引:4,自引:0,他引:4  
Many organisms use structures composed of arrays of cylindersto capture particulate food or molecules form the water or airaround them. The performance of such filters depends on thevelocity of fluid movement through them; hence, mathematicalmodels of flow through fibrous structures can provide insightsabout the functional morphology of biological filters. In thispaper, the authors address the case of feather-like biologicalfilters of finite width and assess several possible models forfluid motion through them by comparing model predictions withobservational data. Two examples of insect appendages are considered:the cephalic fans of black fly aquatic larvae that capture particulatefood and the antennae of adult male moths that catch sex-attractantmolecules released by female moths. The results suggest thatflow through such structures can be much slower than ambientcurrents, that the finest hairs in the structure are the morphologicalfeatures with the greatest effect on leakiness, and that thevelocity of movement (or of ambient flow), as well as the morphologyof such filters, can be critical in determining their performance.  相似文献   
7.
目的:对云南地区习用的藁本品种进行考证。方法:文献调研,实地考察。对文献中记地匠“藁本”进行比较分析,在云南几个主产区、集散地进行实地考察,结合生药鉴定做出评价。结果:通过研究,发现云南地区用的藁本是黄蒿本和黑藁本两个品种,黄藁本的基源是伞形科滇芹属植物滇芹Sinodielsia yunnanensis Wolff和藁本属植物丽江藁本Ligusticum delavayi Franch.,黑藁本的其源是伞形科藁本属植物蕨叶藁本L.pteridophyllum Franch,。结论为现代研究及临床用药提供依据。  相似文献   
8.
Laparoscopic resection for a left adrenal black adenoma   总被引:2,自引:0,他引:2  
Adrenalblackadenoma (pigmentedadenoma)isquiterare Recently,weperformedalaparoscopicresectionforafunctioningadrenalblackadenoma Wereportthecasehere CASEREPORTA 2 1 year oldfemalewasadmittedtoourhospitalbecauseofamenorrheaandobesity ShepresentedwithtypicalCus…  相似文献   
9.
Adrenal black adenoma (pigmented adenoma) is quite rare. Recently, we performed a laparoscopic resection for a functioning adrenal black adenoma. We report the case here.  相似文献   
10.
目的:通过体内外实验探讨荷叶大豆调脂的活性部位及其作用特点,方法:以急性高脂血症小鼠为整体模型观察药物对血清胆固醇及甘油三酯的影响,体外给药观察药物对肝细胞合成胆固醇的影响。结果:荷叶大豆的水提取部分及其生物碱和黄酮均有调脂作用,大豆黄酮对体外肝细胞合成胆固醇有抑制的趋势。结论:荷叶和大豆均有调脂作用,其主要活性部位在黄酮和生物碱,其作用特点在于促进胆固醇的代谢方面。  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