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   1825篇
  免费   101篇
  国内免费   10篇
耳鼻咽喉   8篇
儿科学   53篇
妇产科学   50篇
基础医学   206篇
口腔科学   22篇
临床医学   149篇
内科学   368篇
皮肤病学   8篇
神经病学   194篇
特种医学   63篇
外科学   308篇
综合类   19篇
预防医学   114篇
眼科学   72篇
药学   109篇
中国医学   7篇
肿瘤学   186篇
  2023年   18篇
  2022年   35篇
  2021年   45篇
  2020年   22篇
  2019年   30篇
  2018年   40篇
  2017年   26篇
  2016年   40篇
  2015年   36篇
  2014年   40篇
  2013年   66篇
  2012年   101篇
  2011年   109篇
  2010年   60篇
  2009年   68篇
  2008年   86篇
  2007年   100篇
  2006年   102篇
  2005年   100篇
  2004年   82篇
  2003年   79篇
  2002年   66篇
  2001年   52篇
  2000年   58篇
  1999年   54篇
  1998年   15篇
  1997年   12篇
  1996年   13篇
  1995年   15篇
  1994年   12篇
  1993年   6篇
  1992年   33篇
  1991年   34篇
  1990年   32篇
  1989年   34篇
  1988年   31篇
  1987年   24篇
  1986年   16篇
  1985年   22篇
  1984年   19篇
  1983年   12篇
  1982年   5篇
  1980年   12篇
  1979年   13篇
  1978年   5篇
  1973年   10篇
  1971年   5篇
  1967年   5篇
  1966年   4篇
  1965年   4篇
排序方式: 共有1936条查询结果,搜索用时 15 毫秒
91.
92.
The aim of the present study was to investigate the antibody response to oral poliovirus immunization, and to evaluate the infection morbidity in a group of infants with a positive family history of atopy who were soy-protein-formula fed during the first 6 months of life. We have selected and followed from birth to 4 yr, 107 babies, 18 of whom were exclusively soy-protein-formula fed during the first 6 months of life. All infants were seen at our clinic at the ages of 1, 3, 6, 9, and 12 months, and once-a-year afterwards. They regularly received the oral vaccine against polioviruses at the ages of 3, 5 and 12 months. At age 6, 12 and 24 months, poliovirus type 1, 2 and 3 antibodies were detected. There was no significant difference of seroconversion in the babies, breast, soy or breast and soy fed. Furthermore, no increase in infection morbidity was observed in the soy-protein-formula fed infants. Our data shows that soy-protein-formula feeding in the first 6 months of life does not induce any abnormal antibody response to the oral poliovirus vaccination, as well as no increase in infection morbidity.  相似文献   
93.
Mammary epithelial cells (MECs) were isolated and cultured from mammary glands of healthy women undergoing reduction mammoplasty. Normal MECs were infected with the transforming hybrid virus adeno-5/SV40. Two transformed epithelial cell lines, M1 and M2, were obtained, characterised phenotypically and studied for the production of and the response to cytokines and growth regulators. In both cell lines, expression of the SV40 large T antigen was associated with loss of interleukin 6 (IL-6) production and responsiveness as well as with down-regulation of IL-8 and transforming growth factor (TGF)-alpha production. Both M1 and M2 cell lines were capable of forming colonies in semisolid media, but upon injection into severe combined immunodeficient (SCID) mice only M2 cells were tumorigenic. DNA synthesis in M1 cells was partially inhibited by serum or TNF-alpha and weakly stimulated by hydrocortisone (HC) and IL-8. In contrast, M2 cells were totally unresponsive to a variety of growth regulators. Both lines overexpressed the p53 protein at levels about 20-fold higher than those observed in primary MEC cultures, but no mutations of the p53 gene could be detected. The date confirm the view that the expression in human mammary cells of different oncogenes - including the SV40 T antigen - is frequently associated with alterations of cytokine production and responsiveness.  相似文献   
94.
95.
It is now known that with the use of antiretroviral prophylaxis with zidovudine, elective caesarean section delivery and refraining from breastfeeding the rate of mother-child transmission of HIV infection can be reduced to less than 2%.  相似文献   
96.
The authors report a case of a 10-year-old girl with early involvement of the thyroid gland by non-Hodgkin's lymphoma, an uncommon site of presentation of childhood lymphomas. In pediatrics, thyroid enlargement is more often caused by lymphocytic thyroiditis. The good response to therapy, in spite of the advanced stage of the disease, is noted.  相似文献   
97.
98.
PURPOSE: To investigate in vivo whether ubiquinone Q10 together with vitamin E protects rabbit corneas from keratocyte apoptosis after excimer laser irradiation. METHODS: Photorefractive keratectomy (PRK) was performed in both eyes of three New Zealand white rabbits. During 3 days before surgery, each right eye received four-times-daily instillation of an eye-drop solution containing ubiquinone Q10 0.20% and vitamin E 0.04%; each left eye was treated with a solution that did not contain ubiquinone or vitamin E. The central cornea was analyzed after surgery using the in situ end labelling (ISEL) technique of nicked DNA to detect DNA fragmentation. To determine the number of ISEL positive nuclei, an average of 70 random microscopic fields (five for each de-epithelialized tissue section) of 138,000 mu2 were examined in the right and left cornea samples at 250X by two different observers. RESULTS: Light microscopic examination of the sections from corneas treated before PRK showed that cells committed to apoptosis by PRK were about 50% compared to those of untreated controls. CONCLUSION: Treatment of rabbit eyes before PRK with ubiquinone Q10 lowered the number of apoptotic events.  相似文献   
99.
Multi-unit activity recorded from two electrodes positioned at a distance on a nerve may be analysed by cross-correlation, but units similar in direction and velocity of propagation cannot be distinguished and separately evaluated by this method. To overcome this limit, we added two features, represented by the impulse amplitudes of the paired recordings, to the dimension given by the impulse delay. The analysis was fractionated according to the new dimensions. In experimental recordings from the locomotor appendage of the lobster Homarus americanus, the fractionated analysis proved capable of identifying the contributions of single active units, even if these were superimposed and indiscernible in the global cross-correlation histogram. Up to 5 motor and 10 sensory units could be identified. The shape of the paired impulses was evaluated by an averaging procedure. Analogous evaluations on simulated recordings made it possible to estimate the influences exerted on performance by variations in noise level and in the number and firing rate of active units. The global signal could be resolved into single units even under the worst conditions. Accuracy in evaluating the amount of unit activity varied, exceeding 90% in about half of the cases tested; a similar performance was attained by evaluation of the impulse shapes.  相似文献   
100.
Brain function in the vegetative state   总被引:5,自引:0,他引:5  
Positron emission tomography (PET) techniques represent a useful tool to better understand the residual brain function in vegetative state patients. It has been shown that overall cerebral metabolic rates for glucose are massively reduced in this condition. However, the recovery of consciousness from vegetative state is not always associated with substantial changes in global metabolism. This finding led us to hypothesize that some vegetative patients are unconscious not just because of a global loss of neuronal function, but rather due to an altered activity in some critical brain regions and to the abolished functional connections between them. We used voxel-based Statistical Parametric Mapping (SPM) approaches to characterize the functional neuroanatomy of the vegetative state. The most dysfunctional brain regions were bilateral frontal and parieto-temporal associative cortices. Despite the metabolic impairment, external stimulation still induced a significant neuronal activation (i.e., change in blood flow) in vegetative patients as shown by both auditory click stimuli and noxious somatosensory stimuli. However, this activation was limited to primary cortices and dissociated from higher-order associative cortices, thought to be necessary for conscious perception. Finally, we demonstrated that vegetative patients have impaired functional connections between distant cortical areas and between the thalami and the cortex and, more importantly, that recovery of consciousness is paralleled by a restoration of this cortico-thalamo-cortical interaction.  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