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   1297篇
  免费   61篇
  国内免费   11篇
耳鼻咽喉   6篇
儿科学   41篇
妇产科学   17篇
基础医学   155篇
口腔科学   5篇
临床医学   64篇
内科学   435篇
皮肤病学   4篇
神经病学   70篇
特种医学   70篇
外科学   166篇
综合类   4篇
预防医学   46篇
眼科学   44篇
药学   64篇
中国医学   4篇
肿瘤学   174篇
  2023年   11篇
  2022年   16篇
  2021年   37篇
  2020年   14篇
  2019年   22篇
  2018年   40篇
  2017年   33篇
  2016年   27篇
  2015年   37篇
  2014年   38篇
  2013年   39篇
  2012年   70篇
  2011年   88篇
  2010年   43篇
  2009年   42篇
  2008年   62篇
  2007年   63篇
  2006年   55篇
  2005年   68篇
  2004年   58篇
  2003年   50篇
  2002年   49篇
  2001年   15篇
  2000年   11篇
  1999年   17篇
  1998年   22篇
  1997年   16篇
  1996年   16篇
  1995年   16篇
  1994年   15篇
  1993年   14篇
  1992年   9篇
  1991年   11篇
  1990年   9篇
  1989年   23篇
  1988年   21篇
  1987年   18篇
  1986年   20篇
  1985年   21篇
  1984年   19篇
  1983年   14篇
  1981年   8篇
  1980年   7篇
  1979年   16篇
  1978年   20篇
  1977年   5篇
  1976年   7篇
  1969年   4篇
  1968年   6篇
  1966年   7篇
排序方式: 共有1369条查询结果,搜索用时 15 毫秒
1.
A variant of the HL-60 cell line, HL-60/MCSFR4D2, has been found to express twice the amount of PTP1C as compared to the parental HL-60 cell line by immunoblotting and immunoprecipitation. Differentiation of the variant cells after phorbol 12-myristate 13-acetate (PMA) treatment was examined by the appearance of adherence. In 1% fetal calf serum (FCS), 20% of HL-60/MCSFR4D2 cells exhibited adherence after treatment with 0.5 ng/ml PMA for 48 h, 60% exhibited adherence after treatment with 1.0 ng/ml PMA and 80% exhibited adherence after treatment with 5.0 ng/ml PMA, while HL-60 cells exhibited only a slight response. Furthermore, antisense PTP1C oligonucleotides decreased the PMA-induced adherence of HL-60/MCSFR4D2 cells. These results suggest that the high-expression of PTP1C in HL-60 cells may be involved in the enhancement of susceptibility to macrophage-like differentiation by PMA.  相似文献   
2.
Multi-center clinical trial of 123I-metaiodobenzylguanidine (123I-MIBG) was carried out to assess its utility as a scintigraphic imaging agent reflecting sympathetic neuronal function in cardiovascular field. Studies were performed on patients with heart diseases of three categories, myocardial infarction, angina pectoris and cardiomyopathy. Scintigraphic images, reflecting sympathetic neuronal function were obtained with 123I-MIBG from all of those categories of patients and the efficacy of the imaging was revealed in 781 (95.0%) out of 822 patients. In some patients abnormality was suggested in sympathetic neuronal function with 123I-MIBG imaging, in spite of normal findings with myocardial perfusion scintigraphy by 201TlCl. In all 981 patients studied with 123I-MIBG, there have been no severe adverse reactions, except complaints of burning on injection site of the agent or nausea, etc. from 4 patients. We conclude that 123I-MIBG imaging is one of the effective tools for diagnostic use reflecting topical sympathetic neuronal function in the heart, judging from its safety and efficacy.  相似文献   
3.
Chick embryonic retina was examined in order to investigate morphological changes of the apical portion of retinal pigment epithelial (RPE) cells. Whole retina and RPE sheets were observed by fluorescence microscopy (rhodamine-phalloidin preparation) and transmission electron microscopy. Photoreceptor cells had no inner and outer segments on the 8th day in ovo. The inner segments have been formed on the 15th day and the outer segments on the 19th day. RPE sheets had short and blunt apical processes on the 8th day, elongated and slender ones on the 15th day, and well-developed and melanin-containing processes on the 19th day. RPE of the 19th day had numerous bundles of actin filaments associated with melanin pigments in the basal portion of the apical processes and in the apical cytoplasm. In rhodamine-phalloidin preparations, intense fluorescence was localized in the RPE apical processes and cytoplasm on the 19th day. We concluded that RPE apical processes develop in accordance with the photoreceptor development.  相似文献   
4.
MR appearance of parasymphyseal insufficiency fractures of the os pubis   总被引:1,自引:0,他引:1  
Objective. To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. Design and patients. MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast T1-weighted imaging was also done in three patients. Results and conclusions. MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant disease, so as not to misinterpret it as a chondroid tumor or bone metastasis.  相似文献   
5.
6.
7.
To evaluate the development of renal hypoxia during hemorrhagic shock, fourteen dogs were induced in this study. The animals were divided equally into a group in which mean arterial pressure (MAP) was kept at 50mmHg (group 1), and into another where MAP was kept at 40mmHg for 180mim (group 2). Renal tissue gas tensions were determined by a mass spectrometer. In the 50-mmHg group, renal tissue oxygen tension (PrO 2) dropped for 15min following hemorrhage, remained constant for 90min, then fell further for 150min before a plateau was established. In the 40-mmHg group, the PrO 2 dropped for 90min before reaching a plateau. The second PrO 2 decline occurred at the same level in both the 50-mmHg group and the 40-mmHg group. The point at which the same PrO 2 level occurred for each group suggests the cessation of oxygen consumption and the conditions of renal hypoxia. It is assumed that renal hypoxia occurs in 120min at a MAP of 50-mmHg and in 60min at a MAP of 40mmHg.(Murakawa K, Izumi R, Kobayashi A: Renal tissue gas tentions during hemorrhagic shock. J Anesth 3: 10–15, 1989)  相似文献   
8.
Most gastric mucosa-associated lymphoid tissue (MALT) lymphomas are caused by Helicobacter pylori (H. pylori) infection. We previously reported that acquired lymphoid follicles with germinal centers were induced by H. pylori infection in neonatally thymectomized (nTx) mice. In the present study, we developed gastric MALT lymphoma-like lesions in nTx mice by long-term H. pylori infection, and performed immunogenetic analyses. BALB/c mice were thymectomized on the 3rd day after birth. At 6 weeks of age, mice were orally infected with 10(8) H. pylori and serially killed 2, 4, 6, and 12 months later. Normal BALB/c and noninfected nTx mice served as controls. Follicle formation occurred after 2 months of H. pylori infection in the nTx mice. Follicle formation and infiltration of intraepithelial lymphocytes progressed in a time-dependent manner. Lymphoepithelial lesions, a characteristic feature of MALT lymphoma, also occurred in a time-dependent manner (100% at 12 months). Serum immunoelectrophoresis revealed a monoclonal band (M-protein) in 30% (3/10) of mice 6 months after infection. M-protein-positive mice had amplification of one or two IgM and/or IgG heavy-chain genes in the gastric B lymphocytes, as determined with polymerase chain reaction, suggesting mono- or oligoclonality. Overexpression of Bcl-X(L) protein was immunohistologically observed in the infiltrating B lymphocytes and in some follicular B lymphocytes in 80% (8/10) of the cases at 12 months. Thus, H. pylori infection is involved in the development of gastric MALT lymphoma-like lesions in nTx mice. Our mouse model is useful for clarifying the pathogenetic mechanism of gastric MALT lymphoma by H. pylori infection.  相似文献   
9.
A new commercial rapid 10-min one-step immunochromatography (IC) test, SAS RSV test, was compared to another IC test, Directigen EZ RSV, employing RT-PCR as the "gold standard" for detecting respiratory syncytial virus. Of 102 clinical samples, 79 were positive by RT-PCR, 66 (82.5%) were positive with the SAS RSV test, and 55 (69.6%) were positive with Directigen EZ RSV. The specificity of the new test was 91.3% (21 of 23), similar to that of Directigen EZ RSV (100% [23 of 23]). This test performs well enough to be used for patient care.  相似文献   
10.
Stargardt disease 1 (STGD1) is the most prevalent retinal dystrophy caused by pathogenic biallelic ABCA4 variants. Forty‐two unrelated patients mostly originating from Western China were recruited. Comprehensive ophthalmological examinations, including visual acuity measurements (subjective function), fundus autofluorescence (retinal imaging), and full‐field electroretinography (objective function), were performed. Next‐generation sequencing (target/whole exome) and direct sequencing were conducted. Genotype grouping was performed based on the presence of deleterious variants. The median age of onset/age was 10.0 (5–52)/29.5 (12–72) years, and the median visual acuity in the right/left eye was 1.30 (0.15–2.28)/1.30 (0.15–2.28) in the logarithm of the minimum angle of resolution unit. Ten patients (10/38, 27.0%) showed confined macular dysfunction, and 27 (27/37, 73.7%) had generalized retinal dysfunction. Fifty‐eight pathogenic/likely pathogenic ABCA4 variants, including 14 novel variants, were identified. Eight patients (8/35, 22.8%) harbored multiple deleterious variants, and 17 (17/35, 48.6%) had a single deleterious variant. Significant associations were revealed between subjective functional, retinal imaging, and objective functional groups, identifying a significant genotype–phenotype association. This study illustrates a large phenotypic/genotypic spectrum in a large well‐characterized STGD1 cohort. A distinct genetic background of the Chinese population from the Caucasian population was identified; meanwhile, a genotype–phenotype association was similarly represented.  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