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   322776篇
  免费   10902篇
  国内免费   771篇
耳鼻咽喉   2504篇
儿科学   10372篇
妇产科学   5698篇
基础医学   36460篇
口腔科学   4943篇
临床医学   26513篇
内科学   62648篇
皮肤病学   3516篇
神经病学   30677篇
特种医学   14733篇
外国民族医学   6篇
外科学   50861篇
综合类   4200篇
现状与发展   2篇
一般理论   139篇
预防医学   28555篇
眼科学   5839篇
药学   19647篇
  2篇
中国医学   868篇
肿瘤学   26266篇
  2023年   819篇
  2022年   1239篇
  2021年   2829篇
  2020年   1959篇
  2019年   2826篇
  2018年   24865篇
  2017年   19652篇
  2016年   22058篇
  2015年   4372篇
  2014年   5774篇
  2013年   7508篇
  2012年   17226篇
  2011年   31499篇
  2010年   24577篇
  2009年   17177篇
  2008年   28992篇
  2007年   31821篇
  2006年   10783篇
  2005年   12620篇
  2004年   13217篇
  2003年   13623篇
  2002年   11236篇
  2001年   1728篇
  2000年   1500篇
  1999年   1744篇
  1998年   2291篇
  1997年   1832篇
  1996年   1500篇
  1995年   1383篇
  1994年   1231篇
  1993年   1166篇
  1992年   809篇
  1991年   863篇
  1990年   728篇
  1989年   667篇
  1988年   606篇
  1987年   607篇
  1986年   527篇
  1985年   563篇
  1984年   654篇
  1983年   583篇
  1982年   782篇
  1981年   701篇
  1980年   641篇
  1979年   366篇
  1978年   383篇
  1977年   406篇
  1976年   350篇
  1975年   298篇
  1974年   267篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Bilateral ulnar agenesis is a rare abnormality. A total of 36 cases are analyzed: 35 of these are documented in the literature and 1 stillborn male is presented in this study. Most patients had one of the three conditions: Al-Awadi/Raas-Rothschild syndrome, syndrome of ulnar aplasia with split hand/split foot deformity, or the Brachmann—de Lange syndrome. Fifty percent of all cases with bilateral ulnar agenesis were associated with lower limb defects and these cases, for the most part, also belonged to the aforementioned syndromes. Nonskeletal, internal organ malformations were identified in 34% of all patients. Nine patients presented with isolated bilateral ulnar agenesis. The Al-Awadi/Raas-Rothschild syndrome and the split hand/split foot deformity are heritable disorders. There was no evidence for genetic etiology in most of the other cases. Bilateral ulnar agenesis in our fetus was part of the Brachmann—de Lange syndrome with associated cardiac defect, diaphragmatic hernia, and umbilical artery agenesis.  相似文献   
92.
93.
94.
95.
Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown etiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present study was to investigate the expression of c-erbB-2 protein in the keratinocytes of initial biopsies of oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia. and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using paraffin-embedded tissue sections. Five of the initial biopsies from patients with OMLP expressed the c-erhB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erhB-2 protein, and of the three OMSCC specimens from the patients with OMLP. two were negative and one expressed c-erbB-2 protein. The specimens from the control groups all expressed the c-erhB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.  相似文献   
96.
97.
We have developed a guar wholemeal bread and tested its physiological efficacy and sensory qualities. The objective of the study was to estimate the optimum concentration of guar in bread required to reduce postprandial glycaemia and insulinaemia without adversely affecting the quality of the bread. Following overnight fasts, 15 normal weight, non-diabetic subjects consumed meals of wholemeal bread alone (controls) and supplemented with guar at three different concentrations (5, 10 and 15% replacement of wheat flour). Blood samples for glucose and insulin analysis were taken preprandially, and at 30 and 60 min after the start of each meal. The acceptability of the wholemeal control and guar breads was assessed using a hedonic scaling method. A significantly lower blood glucose rise at 30 min was found after the 15% guar bread meal compared to the control. Plasma insulin responses at 30 and 60 min were significantly lower after the 10 and 15% guar bread meals compared to the controls. Hedonic scores indicated that the subjects found the 5 and 10% guar breads acceptable and in the case of the 5% variety the mean score was identical to the control. We suggest that a guar concentration of between 5 and 10% replacement of wheat flour (wholemeal or white) should be used for the baking of guar wholemeal bread but further work is needed to define the precise quantity of guar required.  相似文献   
98.
Treatment of non-seminomatous testicular cancer often leadsto infertility due to anejaculation/retrograde ejaculation andpoor sperm quality. In these men spermatozoa may be obtainedby transrectal electroejaculation (TE), but the optimal strategyfor assisted procreation in these couples is not known. Ouraim was to examine whether TE and conventional in-vitro fertilization(IVF) would be successful. A total of 10 couples, with long-standinginfertility due to anejaculation or retrograde ejaculation aftertreatment for testicular cancer 5–14 years earlier, werereferred to our unit. All men underwent diagnostic TE undergeneral anaesthesia. Spermatozoa were recovered in nine cases.The antegrade fraction was prepared and used for IVF. Spermquality was variable and conventional IVF was considered impossiblein three cases. Altogether six IVF treatment cycles in six couplesresulted in five pregnancies, of which four resulted in a deliveryand one resulted in a spontaneous abortion. One additional pregnancyis ongoing after transfer of cryopreserved embryos. The fertilizationrate was 54% (33/61) and the cleavage rate was 97% (32/33).No complications relating to the procedure have been encountered.  相似文献   
99.
Transitory increases of ultraviolet transmission on stimulation with light were recorded simultaneously with electroretinogram on and off effects from isolated vertebrate retina. The spectral distribution of the optical light responses coincided with that of NADH reduction. The correlation of the optical, or respiratory, responses and the electrical responses were very close within a wide range of stimulus parameters, suggesting an interpretation in terms of supply and demand of energy with a tight coupling between the two kinds of evoked activity. Prerequisite to the response behaviour was the preservation of synaptic signal transmission from first- to higher-order retinal neurons.  相似文献   
100.
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