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   17025篇
  免费   854篇
  国内免费   114篇
耳鼻咽喉   126篇
儿科学   341篇
妇产科学   201篇
基础医学   1748篇
口腔科学   363篇
临床医学   1201篇
内科学   4516篇
皮肤病学   244篇
神经病学   1159篇
特种医学   693篇
外国民族医学   1篇
外科学   3548篇
综合类   90篇
预防医学   404篇
眼科学   237篇
药学   1096篇
中国医学   25篇
肿瘤学   2000篇
  2023年   116篇
  2022年   218篇
  2021年   386篇
  2020年   231篇
  2019年   305篇
  2018年   356篇
  2017年   315篇
  2016年   357篇
  2015年   399篇
  2014年   487篇
  2013年   566篇
  2012年   969篇
  2011年   979篇
  2010年   574篇
  2009年   478篇
  2008年   842篇
  2007年   849篇
  2006年   907篇
  2005年   925篇
  2004年   861篇
  2003年   860篇
  2002年   883篇
  2001年   386篇
  2000年   379篇
  1999年   375篇
  1998年   190篇
  1997年   161篇
  1996年   135篇
  1995年   126篇
  1994年   132篇
  1993年   107篇
  1992年   256篇
  1991年   305篇
  1990年   252篇
  1989年   246篇
  1988年   243篇
  1987年   218篇
  1986年   175篇
  1985年   170篇
  1984年   143篇
  1983年   131篇
  1982年   63篇
  1979年   108篇
  1978年   64篇
  1975年   57篇
  1973年   51篇
  1971年   64篇
  1969年   67篇
  1968年   61篇
  1966年   67篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A 61 year-old right-handed man, a president of a company fell downstairs and was found unconscious on January 1, 1985. He was admitted to a hospital and he had been unresponsive for 10 days. As he recovered from the consciousness disturbance, he complained of difficulties in discrimination of common objects and in recognition of familiar faces. The patient was admitted to our hospital for the closer examination on July 29, 1985. There was no abnormality in the general physical examination on admission. Neurological examinations revealed no significant deficits except visual field disturbance. In the results of WAIS, the verbal IQ was 108, but the performance IQ was unmeasurable because of a presence of object agnosia. His spontaneous speech was fluent without paraphasia, perseveration or dysprosody. His auditory comprehension of spoken language and repetition were spared. Neuropsychological examinations revealed an impairment in the recent verbal memory, alexia, agraphia, object agnosia, color naming difficulty, prosopagnosia and visuospatial constructional disability. The patient exhibited three major neuropsychological characteristics. Firstly, the recognition of the objects which were presented by the photograph or line drawing was more severely impaired than the real objects. Secondly, the object naming difficulty was more pronounced in the presentation at an unusual angle than in the free presentation. Thirdly, the patient made poor performance in reproduction of the models by photographic presentation as compared with the presentation of the real models in the three-dimensional block construction test. The CT scan performed on January 4, 1985 demonstrated subcortical hematomas with surrounding edema in the temporo-occipital regions of both hemispheres.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
72.
We measured the serum levels of manganese-superoxide dismutase (Mn-SOD) in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Serum Mn-SOD level for normal subjects was 94.1 +/- 23.5 ng/ml (mean +/- S.D.), the levels for AML and ALL patients were 159.6 +/- 77.1 ng/ml and 154.4 +/- 77.0 ng/ml, respectively. The serum Mn-SOD levels were unrelated to individual intracellular Mn-SOD levels, but correlated well with serum lactate dehydrogenase values. Regression of the leukemia was accompanied by decrease in the serum level of Mn-SOD. Serum Mn-SOD may thus serve as a measure of the activity of the disease.  相似文献   
73.
Many asthmatic children have experienced atopic dermatitis in their younger days. As it is very difficult to cure childhood asthma we attempted to determine the anti-allergic drug effects in preventing the development of asthma by using ketotifen on atopic dermatitis patients. The study was designed as a placebo controlled double blind trial of 128 atopic dermatitis patients aged from 2-34 months. 91 patients were given complete analysis in the study, 33 patients were given only a safety rate and 4 patients were dropped. The 91 patients were followed for 52 weeks. Our primary finding was that the development of bronchial asthma was inhibited in the ketotifen group compared to the placebo controlled group with a statistically significant degree (p less than 0.001). We also found that clinical symptoms of atopic dermatitis were significantly improved in the ketotifen group (p less than 0.001). Only 5 patients complained of mild side effects.  相似文献   
74.
Background The purpose of this study was to examine the effects of bacterial suporantigens, which can derange the immune response and contribute to the renal lesions of immunoglobulin A (lgA) nephropathy. Methods Twenty-five micrograms of a bacterial superantigen, staphylococcal enterotoxin B (SEB), was injected into IgA nephropathy-prone ddY mice intrathymically when they reached 6 weeks of age. Evaluation included measurement of albumin excretion in urine, immunoglobulin concentration, and lymphokine production in vitro, as well as analysis of T-cell receptor expression in splenic T-cell subsets and examination of renal histology by light and fluorescence microscopy. Results At 40 weeks of age, the serum level of IgA in these mice was substantially increased and the number of Vβ8+ CD4+splenic T-cells was significantly decreased compared with measurements in untreated controls. Both control and SEB-treated mice excreted less than 30 μg/mL of urinary albumin. In mice given SEB, the amount of interleukin 2 (IL-2) and tumor necrosis factor-α (T helper 1 [Th1]-type cytokines) produced by the in vitro-stimulated lymphocytes significantly decreased. whereas that of interleukin 4 (IL-4) and interleukin 6 (IL-6) (Th2-type cytokines) markedly increased compared with measurements in control mice. At 40 weeks of age, mice given SEB showed marked glomerular hypercellularity and enhanced glomerular C3 deposition by renal histology, compared with control mice. Conclusion These results suggest that bacterial superantigen SEB may modify glomerular lesions through activating Th2 cells, while inducing deletion of Th1 cells in this experimental model.  相似文献   
75.
Testicular development was studied in prepubertal boys with retractile testes. Testicular volume, the diameter of the seminiferous tubules and the number of spermatogonia in the tubules were decreased in cases of unilateral retractile testis, when compared with values for the contralateral normally descended testis. On the other hand, in patients with a unilateral retractile testis and contralateral inguinal testis, there was no difference in the developmental parameters between the two testes. These results suggest that the retractile testis has developmental failures characteristic of a cryptorchid testis and therefore requires orchiopexy.  相似文献   
76.
Clinical evaluation of cefmenoxime (CMX, Bestcall) was performed against infections associated with hematological, respiratory tract and other disorders. Clinical effectiveness of CMX against severe infections with hematological disorders including sepsis, pneumonia, pyelitis and so on was 74.4% for good responses and against the respiratory tract infections, 96.2% for good responses was obtained. Neither objective or subjective side effects nor extreme abnormalities in laboratory tests were observed in these patients. It can be concluded, therefore, that CMX is one of the most useful drugs against infectious diseases associated with hematological disorders, respiratory tract and other disorders.  相似文献   
77.
Using differential radiation sensitivity of components of mouse embryonal thymus, an in vitro method for studying T-cell differentiation from hemopoietic stem cells (HSCs) in the G0 phase was established. Intrathymic T-cell precursors present in embryonal thymus were found to be quite radioresistant (up to 20 Gy), and consequently 25-Gy-irradiated embryonal thymic lobes were used. Thymic lobes (25-Gy irradiated) taken from mouse fetuses (gestation day 15) were placed in Millipore-HA culture plates supported on squares of gelatin foam sponge in 24-well culture plates in which neonatal thymus stromal cells were cultured. HSCs (10(5) cells per well) in the G0 phase were added to these thymic lobes and cocultured at 37 degrees C in a 5% CO2/95% air incubator. Half the culture medium was changed every week. After 3 weeks, a large number of colonies had formed. Immunohistochemical studies and fluorescence-activated cell sorter analyses revealed that the colonizing cells regularly develop and exhibit surface markers characteristic of T cells (Thy-1, IL-2R, L3T4, Lyt-2, etc.). In situ hybridization analyses revealed that mRNA expression for T-cell receptor (TCR) beta chains occurred within colonizing cells. Using a monoclonal antibody (F23.1), expression of TCR beta-chain variable domain (V beta 8) on the surface of these developing T cells was demonstrated. These cells responded to interleukin 2 and/or anti-CD3 monoclonal antibody, indicating functional T cells. This method will be useful in studying T-cell differentiation pathways from pluripotent HSCs and in clarifying the mechanisms involved in negative and positive selection of T cells within the thymus.  相似文献   
78.
79.
Eosinophilic bronchitis without asthma can cause a persistent non-productive cough which is resistant to bronchodilator therapy. To understand the mechanism of the cough in this disorder, an animal model of eosinophilic bronchitis was developed. Guinea-pigs were treated with transnasal administration of polymyxin B or saline twice a week for 3 weeks. The number of eosinophils in bronchoalveolar lavage fluid increased in polymyxin B-treated animals when compared with those treated with saline. In addition, histological examination showed that the number of eosinophils infiltrated into the tracheal epithelium increased; injury to the tracheal epithelium was greater in polymyxin B-treated animals. The numbers of coughs induced by saline and each concentration of capsaicin (10–18, 10–16, 10–14M) were greater in the polymyxin B-treated animals. FK-224 (a neurokinin receptor antagonist) decreased the heightened cough reflex in this animal model of eosinophilic bronchitis. These findings suggest that neuropeptides, and particularly neurokinins, are involved in the heightened cough receptor sensitivity in eosinophilic bronchitis without asthma. This has implications for better understanding of this disorder and its treatment.  相似文献   
80.
A 31-year-old adult with an aortico-left ventricular tunnel (ALVT) arising from the right aortic sinus is reported. Preoperative transesophageal echocardiography demonstrated a ruptured sinus of Valsalva with severe aortic valve regurgitation which originated from the right coronary sinus entering the outlet portion of the left ventricular outflow tract. Operation revealed the aortic entrance of the tunnel was above the right coronary sinus. Direct closure of the orifice of the tunnel using three stitches of 4-0 polypropylene with felt and aortic valve replacement (AVR) was performed. At 10-month follow-up the patient is asymptomatic and receiving no oral medications except anticoagulants. We believe this to be the oldest case of ALVT managed with AVR.  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