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   81197篇
  免费   6267篇
  国内免费   158篇
耳鼻咽喉   920篇
儿科学   2404篇
妇产科学   1822篇
基础医学   12768篇
口腔科学   1675篇
临床医学   8628篇
内科学   16087篇
皮肤病学   1865篇
神经病学   8959篇
特种医学   2845篇
外国民族医学   6篇
外科学   10543篇
综合类   437篇
一般理论   29篇
预防医学   6283篇
眼科学   1106篇
药学   5802篇
中国医学   113篇
肿瘤学   5330篇
  2023年   633篇
  2022年   646篇
  2021年   1459篇
  2020年   1300篇
  2019年   1717篇
  2018年   2300篇
  2017年   2006篇
  2016年   2195篇
  2015年   2140篇
  2014年   2508篇
  2013年   3807篇
  2012年   5125篇
  2011年   5128篇
  2010年   2833篇
  2009年   2329篇
  2008年   4457篇
  2007年   4425篇
  2006年   4196篇
  2005年   3946篇
  2004年   3768篇
  2003年   3630篇
  2002年   3593篇
  2001年   2251篇
  2000年   2386篇
  1999年   1840篇
  1998年   869篇
  1997年   685篇
  1996年   547篇
  1995年   510篇
  1994年   486篇
  1993年   431篇
  1992年   786篇
  1991年   822篇
  1990年   799篇
  1989年   751篇
  1988年   682篇
  1987年   658篇
  1986年   614篇
  1985年   656篇
  1984年   568篇
  1983年   469篇
  1982年   360篇
  1981年   315篇
  1980年   275篇
  1979年   432篇
  1978年   332篇
  1977年   288篇
  1975年   282篇
  1974年   254篇
  1973年   242篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
BACKGROUND: The role of large colony streptococci groups C or G as pathogen agents in sore throat has been questioned. AIM: To analyse clinical features of patients with large colony streptococci groups C or G compared with patients with group A streptococci (GAS) and with negative cultures. DESIGN OF STUDY: Prospective study of patients with sore throat. SETTING: Two Norwegian general practices in Stokke and Kongsberg communities with 6500 patients.METHOD: Frequency of clinical features in the three patient categories including the four Centor criteria (fever, anterior cervical lymphadenopathy, tonsillar exudates, and lack of cough), degree of pain on swallowing, pharyngeal rubor, C-reactive protein (CRP) values, patient age between 3 and 14 years, and duration of symptoms before seeing the doctor. A logistic regression analysis to find independent predictors was performed. RESULTS: Out of 306 patients with a sore throat, 244 were adults and 62 were children under 10 years old; 40% were men. One hundred and twenty-seven had GAS, 33 had streptococci groups C or G, and 146 had negative throat cultures. Forty-eight per cent of the GAS patients and 45% of the C or G patients met three or four of the Centor criteria. The logistic regression revealed that in patients with GAS considerable pain on swallowing, an age of 3-14 years and a duration of symptoms of < or =3 days or less were significantly associated with GAS infection in addition to the Centor criteria. The same results were found when all streptococci were analysed together, in addition elevated CRP was significant. In patients with streptococci group C or G an elevated CRP-value was significantly associated. CONCLUSION: Patients with tonsillitis caused by streptococcus groups C or G have, to a large extent, the same clinical picture as patients with GAS. Large colony streptococci groups C and G should be considered as throat pathogens in line with GAS.  相似文献   
113.
114.
A cytomorphometric analysis of superficial vaginal cells inwomen in three groups of different types of hormonal concentrationwas made. There were 15 women in each group. Group I was studiedduring a natural cycle, group II under oral contraceptive therapyand group III during an in-vitro fertilization (IVF) stimulationprotocol. Morphometric parameters were measured on an imageanalyser. The area, perimeter and several form factors weremeasured separately for nuclei and cytoplasm. The nucleus:cytoplasmicratio was also determined. The cytoplasmic area was significantlyreduced in group II and was associated with a statisticallysignificant reduction of the nuclear area. The nucleus:cytoplasmicratio appeared significantly increased in group II and reducedin group III. Low oestradiol impregnation obtained with an oralminidosed contraceptive interfered with vaginal cell maturation.High oestradiol concentrations obtained during IVF protocolsinduced marked nuclear pycnosis but did not induce supra-physiologicalcell enlargement. Maximal cell size is genetically regulatedaccording to Driesch's law of volume invariance and hormonalover-stimulation has no effect on cell size. The nucleus:cytoplasmicratio appears to be a powerful parameter reflecting the oppositeeffects of hormones on cell compartments.  相似文献   
115.
The effects of scopolamine, an anticholinergic drug, of trimipramine, a tricyclic antidepressant with both anticholinergic and sedative properties, of diazepam and a placebo, on explicit memory and repetition priming were assessed using a free-recall task and a word-stem completion task. Forty-eight healthy volunteers took part in this double-blind study. Diazepam provoked a dissociation between free recall, which was profoundly impaired, and word completion, which was spared. No significant changes in memory performances were observed in the scopolamine group; however, a significant correlation between explicit and implicit memory performances was observed in this group. At the low dose used, the effects of trimipramine on memory were mild. The results suggest that the cholinergic system is involved in the priming effect.  相似文献   
116.
117.
Experimental composites using either bisGMA/TEGDMA or UEDMA/ TEGDMA matrices, quartz or barium glass fillers, and 2 different filler silanization methods were evaluated regarding monomer leachability in distilled water. The leached amount was detected and quantified using gas chromatography. The results showed that twice as much TEGDMA is leached from a bisGMA/TEGDMA based composite than from an UEDMA/ TEGDMA based composite, when both contain 50 wt% TEGDMA. The hypothesis suggested that the higher degree of cure of UEDMA/TEGDMA based composites would be reflected in a lower monomer leaching value, and this hypothesis was supported by the findings. Whether such a correlation exists within groups of UEDMA/TEGDMA based matrices having different degrees of cure was not determined and needs to be investigated in future studies. Variables such as filler composition and silane treatment did not affect the leaching values of TEGDMA in water. That finding suggests that future studies should target differences in matrices, and that the need for considering effects of filler composition and silane treatment methods should not receive the same priority.  相似文献   
118.
119.
The hypothesis that differences in drug effects of risperidone and haloperidol on negative symptoms in schizophrenia are secondary to effects on positive, extrapyramidal, and depressive symptoms was investigated by means of an analysis of the data from the USA-Canada risperidone double-blind randomized clinical trial of 523 chronic schizophrenic patients. Regression analyses in the total sample and within treatment groups confirmed a strong relationship between changes in negative symptoms and the other variables studied (R2=0.50–0.51,p<0.001). Only depressive symptoms did not contribute significantly to these results (p>0.10). Path analysis showed that the greater mean change (p<0.05) of negative symptoms with risperidone compared to haloperidol could not be fully explained by correlations with favourable effects on positive and extrapyramidal symptoms. The relationship between shift in extrapyramidal symptoms and shift in negative symptoms failed to reach statistical significance; however, there was a clear tendency in the expected direction in both treatment groups.  相似文献   
120.
Liver transplantation in HBsAg positive patients   总被引:1,自引:0,他引:1  
  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