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   461篇
  免费   35篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   10篇
妇产科学   22篇
基础医学   85篇
口腔科学   5篇
临床医学   39篇
内科学   81篇
皮肤病学   12篇
神经病学   49篇
特种医学   6篇
外科学   78篇
综合类   6篇
预防医学   22篇
眼科学   13篇
药学   32篇
中国医学   6篇
肿瘤学   25篇
  2023年   8篇
  2022年   35篇
  2021年   24篇
  2020年   8篇
  2019年   26篇
  2018年   26篇
  2017年   13篇
  2016年   21篇
  2015年   21篇
  2014年   24篇
  2013年   28篇
  2012年   38篇
  2011年   27篇
  2010年   20篇
  2009年   11篇
  2008年   21篇
  2007年   19篇
  2006年   20篇
  2005年   19篇
  2004年   16篇
  2003年   14篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   6篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   5篇
  1991年   1篇
  1990年   4篇
  1989年   3篇
  1988年   1篇
  1987年   3篇
  1986年   5篇
  1985年   1篇
  1984年   2篇
  1981年   1篇
  1979年   1篇
排序方式: 共有497条查询结果,搜索用时 15 毫秒
101.
102.
In the present study, 12 indigenous diesel‐oil‐degrading bacteria were isolated from the petroleum‐contaminated soils of the Changqing oil field (Xi’an, China). Measurement of the diesel‐oil degradation rates of these strains by the gravimetric method revealed that they ranged from 42% to 66% within 2 weeks. The highest degradation rates were observed from strains CQ8‐1 (66%), CQ8‐2 (62.6%), and CQ11 (59%), which were identified as Bacillus thuringiensis, Ochrobactrum anthropi, and Bordetella bronchialis, respectively, based on their 16S rDNA sequences. Moreover, the physiological and biochemical properties of these three strains were analyzed by Gram staining, catalase, oxidase, and Voges–Proskauer tests. Transmission electron microscopy showed that all three strains were rod shaped with flagella. Gas chromatography and mass spectrometric analyses indicated that medium‐ and long‐chain n‐alkanes in diesel oil (C11–C29) were degraded to different degrees by B. thuringiensis, O. anthropi, and B. bronchialis, and the degradation rates gradually decreased as the carbon numbers increased. Overall, the results of this study indicate strains CQ8‐1, CQ8‐2, and CQ11 might be useful for environmentally friendly and cost‐effective bioremediation of oil‐contaminated soils.  相似文献   
103.
Respiratory infections, especially those of the lower respiratory tract, remain a foremost cause of mortality and morbidity of children greater than 5 years in developing countries including Pakistan. Ignoring these acute‐level infections may lead to complications. Particularly in Pakistan, respiratory infections account for 20% to 30% of all deaths of children. Even though these infections are common, insufficiency of accessible data hinders development of a comprehensive summary of the problem. The purpose of this study was to determine the prevalence rate in various regions of Pakistan and also to recognize the existing viral strains responsible for viral respiratory infections through published data. Respiratory viruses are detected more frequently among rural dwellers in Pakistan. Lower tract infections are found to be more lethal. The associated pathogens comprise respiratory syncytial virus (RSV), human metapneumovirus (HMPV), coronavirus, enterovirus/rhinovirus, influenza virus, parainfluenza virus, adenovirus, and human bocavirus. RSV is more dominant and can be subtyped as RSV‐A and RSV‐B (BA‐9, BA‐10, and BA‐13). Influenza A (H1N1, H5N1, H3N2, and H1N1pdm09) and Influenza B are common among the Pakistani population. Generally, these strains are detected in a seasonal pattern with a high incidence during spring and winter time. The data presented include pneumonia, bronchiolitis, and influenza. This paper aims to emphasise the need for standard methods to record the incidence and etiology of associated pathogens in order to provide effective treatment against viral infections of the respiratory tract and to reduce death rates.  相似文献   
104.
The population explosion and unintended pregnancies, sexually transmitted diseases including human immunodeficiency virus, and cervical cancer, are major challenges to health worldwide. Their prevention might be achieved through vaccination-based approaches to activate specific immunity against pathogen- or fertility-associated antigens in the female genital tract (FGT). This article aims to review methodologies for enhancing adaptive immunity in the FGT to maximize the response to vaccination. Most components of the adaptive and innate mucosal immune system are present in the FGT and several features are common with the nasopharynx/bronchial and gastrointestinal tracts. In contrast to other mucosal sites, the FGT has minimal local lymphoid tissue. Other sites primarily produce IgA and IgM while in the FGT, especially the vaginocervix, IgG is the predominant immunoglobulin secreted. In rodents, data exist to substantiate a common mucosal immune system interconnecting the nasal/bronchial, gastrointestinal, and female genital tracts. The intranasal route seems the most efficacious to induce an immunity in the FGT especially when combined with a systemic or parenteral route. In humans, for induction of secretory IgA and IgG antibodies in the FGT, immunization by the nasal or the vaginal route is effective. In vaginal immunization, a strong and consistent antibody response is best achieved following vaccination during the follicular phase of the menstrual cycle. Antibodies administered systemically percolate into the FGT and can provide immunoprotection against target molecules or cells. Thus, as well as active immunization using selected routes, the passive immunization approach may provide a viable alternative to vaccinology for future development.  相似文献   
105.
Recently, the authors reported a novel dodecamer peptide sequence, designated as YLP12 on human sperm, that is involved in binding to zona pellucida (ZP) of human oocyte [10]. This unique sequence is present on the acrosomal region of the human sperm cell and is expressed only in human testis/ sperm. The aim of the present study was to examine whether YLP12 sequence is involved in capacitation/acrosome reaction. Swim-up sperm were capacitated with anti-YLP12 Fab' antibodies or control Fab's (40 and 85 microg/mL) and then the acrosome reaction was induced with calcium ionophore. An average of 64-73% sperm underwent acrosome reaction when they were capacitated in the presence of 40-85 microg/mL of bovine serum albumin or control Fab's. A significant (p < .01 to < .001) reduction (58-75%) in the percentage of acrosome-reacted sperm was observed when the sperm were capacitated in the presence of YLP12 Fab's. These data indicate that the YLP12 peptide sequence is involved in sperm capacitation / acrosome reaction, and may find clinical applications in the diagnosis and treatment of male infertility and immunocontraception.  相似文献   
106.
107.
108.
Journal of Assisted Reproduction and Genetics - The present study was conducted to investigate the expression and possible role of the c-mycprotooncogene in preimplantation embryos by using...  相似文献   
109.
Sperm samples were collected from male partners of fertile and infertile couples having unexplained and male factor infertility and analyzed for morphological abnormalities. After a staining procedure, sperm samples of these infertile men showed a variety of abnormalities. The sperm samples were also studied for their binding with the Abs directed against protamine (the nuclear protein), fertilization antigen (FA-1, sperm surface antigen), and the lithium diiodosalicylate- (LIS-) solubilized sperm preparation, and the binding was correlated with the percentage of morphologically abnormal sperm in the sample. Abs used in the present study were raised in female rabbits and had high titers (ELISA titers, 1:4096 to 1:8196), and recognized no band (anti-protamine), one 49,000- +/- 2000-dalton band (anti-FA-1), and at least 8 bands of various molecular identities in the 14,000- to 92,000-dalton range (anti-LIS sperm) on the Western blot of LIS-solubilized human sperm. The affinity-purified Fab' antibodies were iodinated and used in a radioimmunobindingassay for testing their binding with the sperm cells. Anti-protamine Fab's showed minimal binding and the binding activity (cpm bound/10 x 10(6) sperm cells) did not correlate (head defect, r = .12; midpiece defect, r = .07; tail defect, r = .11) significantly with percentage of abnormal cells in the sample. The binding of the anti-FA-1 Fab's also did not show a significant correlation (head defect, r = .29; midpiece defect, r = .48; tail defect, r = .23), though a positive trend (p = .05) was observed with the midpiece defect. In contrast, the binding of anti-LIS sperm Fab's demonstrated a significant correlation with the percentage of abnormal sperm cells in the sample (head defect, r = .51, p = .04; midpiece defect, r = .80, p less than .0001; tail defect, r = .23, p = .039). With an increased percentage of abnormal sperm cells, especially those with midpiece defect, there was an increased binding of anti-LIS sperm Fab's. These results suggest that with an increase in percentage of abnormal sperm, there is a change in antigenicity of the sperm cells. An increase in structural abnormality may enhance antibody binding to an abnormal sperm cell, thus causing a further decrease in its fertilizing capacity.  相似文献   
110.
Objective: In female cancer survivors, the accelerated loss of primordial follicles may lead to premature ovarian failure. We investigated the protective effects of bone marrow derived mesenchymal stem cells (BMMSC) and gonadotropin releasing hormone analogue (GnRHa) against chemotherapeutic-induced ovarian toxicity in a rat model.

Material and methods: Forty-eight Wistar albino female rats were divided into four groups. Group 1 was composed of rats that were given 200?mg/kg cyclophosphamide injection for each cycle (two cycles for each rat). Both cyclophosphamide and 0.4?µg GnRHa were administered to Group 2. Cyclophosphamide and 4 million/kg BMMSC were administered to Group 3. Cyclophosphamide, GnRHa, and BMMSC were administered to Group 4. Germ cell apoptosis, DNA fragmentation and primordial follicular count were investigated with Cleave Caspase-9 and TUNEL analysis. The presence of the SRY gene on the Y chromosome in the ovary of the recipient female rats was checked with PCR.

Results: Immunohistochemical staining (IHS) of Caspase-9 and TUNEL was higher in Group 1 than in Group 3 (p?p?SRY gene was detected in Groups 3 and 4 with the PCR analysis. The mean primordal follicle count was lowest in Group 1 and the mean primordial follicle counts were higher in Groups 2 and 3 than in Group 1. The difference between Group 1 and Group 4 was not significant.

Conclusion: BMMSC therapy was found to be protective from germ cell apoptosis and DNA damage when it was used with chemotherapy regimens including alkylating agents.  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