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   1982篇
  免费   167篇
  国内免费   57篇
耳鼻咽喉   43篇
儿科学   43篇
妇产科学   19篇
基础医学   210篇
口腔科学   29篇
临床医学   184篇
内科学   384篇
皮肤病学   24篇
神经病学   115篇
特种医学   65篇
外国民族医学   1篇
外科学   306篇
综合类   189篇
现状与发展   3篇
预防医学   148篇
眼科学   30篇
药学   190篇
  2篇
中国医学   63篇
肿瘤学   158篇
  2024年   7篇
  2023年   28篇
  2022年   46篇
  2021年   67篇
  2020年   60篇
  2019年   44篇
  2018年   47篇
  2017年   47篇
  2016年   49篇
  2015年   66篇
  2014年   78篇
  2013年   82篇
  2012年   106篇
  2011年   151篇
  2010年   93篇
  2009年   71篇
  2008年   89篇
  2007年   100篇
  2006年   93篇
  2005年   114篇
  2004年   68篇
  2003年   101篇
  2002年   85篇
  2001年   72篇
  2000年   51篇
  1999年   60篇
  1998年   38篇
  1997年   27篇
  1996年   29篇
  1995年   16篇
  1994年   20篇
  1993年   7篇
  1992年   22篇
  1991年   23篇
  1990年   25篇
  1989年   24篇
  1988年   9篇
  1987年   16篇
  1986年   11篇
  1985年   6篇
  1983年   4篇
  1975年   4篇
  1974年   3篇
  1972年   5篇
  1971年   3篇
  1970年   3篇
  1969年   4篇
  1968年   8篇
  1967年   3篇
  1966年   3篇
排序方式: 共有2206条查询结果,搜索用时 15 毫秒
11.
12.
The antigenic sites on the major allergen from yellow mustard (Sinapis alba L.) seeds were studied using murine (BALB/c) monoclonal antibodies (mAb) and human IgE antibodies. Ten IgG1 (K) mAb from two fusions were analyzed. Competition and complementation studies performed with peroxidase labeled mAb reveal the existence of two main antigenic sites in Sin a I. All the described mAb failed to recognize the unordered carboxyamidomethylated polypeptide chains, with the single exception of 2B3, which binds the alkylated large chain. However, this mAB cannot react with the tetranitromethane-modified protein which retains the native conformation. This fact suggests that the only tyrosine of Sin a I, located in the large chain, may be part of a sequential epitope of the allergen. This chemical modification also alters the binding of the mAb 4A11 and 3F3 to the allergen, besides 2B3. The three mAb belong to the same complementation group. Specific IgE binding cannot be inhibited either by the large or small carboxyamidomethylated polypeptide chains, while the nitrated allergen shows a weaker inhibitory activity than the native Sin a I. 4A11, which is a tyrosine-dependent mAb, causes the greatest binding inhibition of the tested mAb on human IgE from atopic individuals, as determined from a reverse enzyme immunoassay, suggesting an important role played by tyrosine in the immunochemical recognition of Sin a I.  相似文献   
13.
We have previously demonstrated that it is possible to induce a consistent and strong cytolytic T lymphocyte (CTL) response to synthetic peptides, corresponding to poorly immunogenic malaria CTL epitopes, by co-injecting them with peptides representing defined T helper (Th) epitopes in incomplete Freund's adjuvant (IFA). In this study we have tested different immunization protocols to improve further the elicitation of the CTL response. We show that the CTL response to a mixture of Th + CTL peptides administered in IFA was further enhanced by a previous injection of the Th epitope peptide in IFA. Moreover, we found that the response could be significantly augmented by a pre-injection of IFA alone. This enhancement was observed only if the Th epitope was also present in the second injection. The number of lymph node cells recovered was 2–3-fold higher in mice pre-injected with IFA, but the increase in specific CTL activity, expressed as lytic units per animal, by pre-injection of IFA was at least 10–20-fold. Thus, pre-injection of IFA clearly increases the magnitude of a subsequent CTL response.  相似文献   
14.
High levels of growth factors and their receptors have been demonstrated in human tumors. Gliomas and meningiomas are characterized by overexpression of epidermal growth factor receptor (EGF-R). Ior egf/r3, is a neutralizing murine monoclonal antibody (MAb) against EGF-R, and was generated at the Cuban Institute of Oncology. The antibody recognizes EGF-R with high affinity, inhibiting tyrosine kinase activation. A clinical trial was conducted in brain tumor patients to evaluate toxicity, immunogenicity, and clinical benefit of escalating doses of the antibody. Nine patients with histologically confirmed gliomas or meningiomas, who had active or recurrent disease after receiving conventional treatment, received four intravenous doses of ior egf/r3. Total dosages ranged from 160 to 480 mg. As inclusion criteria, radioimmunoscintigraphy with the same MAb labeled with 99mTechnetium (99mTc) was performed. Immune response against the murine antibody was also evaluated. After four doses of ior egf/r3 MAb, no significant toxicity was found, except in one patient who developed a grade 4 allergic adverse event. This reaction was probably related with previous sensitization to the same MAb and the development of human anti-mouse antibodies (HAMA) response. Despite no major objective antitumor responses, eight patients had stable disease on the 6-month evaluation, and two patients remain alive after four years of MAb therapy.  相似文献   
15.
Taurine increases in brain extracellular space due to glutamate agonists were studied in vivo in the rat hippocampus using a dialysis technique, both in the absence and in the presence of glutamate receptor antagonists. Extracellular taurine levels increased during perfusions of agonists, listed in descending order of potency: kainate (KA), N-methyl-D-aspartate (NMDA), and quisqualate (QA). While taurine increases due to KA or QA perfusions were inhibited by 6,7-dinitro-quinoxaline-2,3-dione (DNQX), those induced by NMDA were abolished in the presence of 3-(carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). These results indicate that increases in extracellular taurine levels evoked by NMDA, KA or QA in the rat hippocampus are caused by activation of their specific receptors. Field potentials, concomitantly recorded, were quickly abolished during NMDA or KA perfusions (0.1 mM), while QA (0.25 mM) induced the appearance of bicuculline-like evoked responses. Since taurine has been proposed as an osmoregulatory substance in the rat brain, and cell swelling is known to be an early component of glutamate agonists neurotoxicity, the increases in extracellular taurine reported here could be due to taurine released through an osmoregulatory process, counteracting the neurotoxic cellular oedema induced by glutamate agonists.  相似文献   
16.
Constitutional mutations in the RB1 gene predispose to retinoblastoma development. Hence genetic screening of retinoblastoma patients and relatives is important for genetic counseling purposes. In addition, RB1 gene mutation studies may help decipher the molecular mechanisms leading to tumors with different degrees of penetrance or expressivity. In the course of genetically screening of 107 hereditary and non-hereditary retinoblastoma patients (11 familiar bilateral, 4 familiar unilateral, 49 sporadic bilateral and 43 sporadic unilateral) and kindred from Spain, Colombia and Cuba, using direct PCR sequencing, we observed 45 distinct mutations and four RB1 deletions in 53 patients (9 familiar bilateral, 2 familiar unilateral, 31 sporadic bilateral and 11 sporadic unilateral). Most of these mutations (26/45, 57%) have not been reported before. In 32 patients, the predisposing mutations correspond to nonsense (mainly CpG transitions) and small insertions or deletions whose expected outcome is a truncated Rb protein that lacks the functional pockets and tail. Five single aminoacid replacements and seventeen mutations affecting splicing sites were also observed in retinoblastoma patients. Two of these sixteen mutations are of unclear pathogenic nature.  相似文献   
17.
BACKGROUND: This study was conducted on human cervical mucus using light microscopy (LM) and scanning electron microscopy (SEM). The objective was the morphological characterization of the different mucus types, with samples taken from the lumen of the cervix and from the different secretory zones of the cervical mucosa. METHODS: A total of 230 samples from 195 women were spread out on slides and air dried. The phenomenon of 'ferning' was observed and assessed in these samples using both LM and SEM. Further samples from the lumen of the cervix and the different secretory crypts were spread out on cover slips and fixed with glutaraldehyde (2.5%) to be studied by SEM. RESULTS: The results show the presence of four different morphological mucus types, namely L, S, P and G, in both types of sample using dried and fixed techniques. CONCLUSIONS: Mucus from the lumen of the cervix appears to be a morphologically heterogeneous entity. It contains different types of secretions, the proportions of which vary throughout the menstrual cycle. The different mucosal types show different types of crystallization, different patterns of ultrastructure (probably related to the arrangement of the glycoprotein network) and are produced in different secretory zones of the crypts in the cervix.  相似文献   
18.
The ERAS guidelines are intended to identify, disseminate and promote the implementation of the best, scientific evidence-based actions to decrease variability in clinical practice. The implementation of these practices in the global clinical process will promote better outcomes and the shortening of hospital and critical care unit stays, thereby resulting in a reduction in costs and in greater efficiency. After completing a systematic review at each of the points of the perioperative process in cardiac surgery, recommendations have been developed based on the best scientific evidence currently available with the consensus of the scientific societies involved.  相似文献   
19.
健脑安治疗血管性痴呆肾虚痰浊证的单盲对照研究   总被引:2,自引:0,他引:2  
目的 评价健脑安治疗血管性痴呆肾虚痰浊证的临床疗效,论证补肾降浊法是否为治疗血管性痴呆的一种有效疗法。方法 6周随机单盲对照临床试验。40例轻中度VD病人,治疗组25例,对照组15例。治疗组给予口服复方中药制剂健脑安片,1片/次,3次/d。对照组给予口服都可喜片,40mg/次,2次/d。结果 健脑安能显改善血管性痴呆肾虚痰浊证,并且其改善肾虚痰浊证的疗效显优于都可喜(P<0.05)。结论 健脑安对血管性痴呆患肾虚痰浊证的疗效显优于都可喜。补肾降浊法为治疗血管性痴呆的有效治法,具有指导临床治疗痴呆用药和进一步临床研究的价值。  相似文献   
20.
Urinary infection due to urea splitting bacteria leads to a rise in urinary pH, favouring the precipitation of calcium salts and struvita crystals. If deposited on the surface of a bladder with chronic inflammation or some other previous lesion, may produce an alkaline encrusted cystitis, now a rare condition. In the case here presented, occurred in a 69-year-old male. Corynebacterium urealyticum grown in the urine, and some foci of malakoplakia were found in the area of encrustation endoscopically excised. This case seems to be the third example of alkaline encrusted cystitis associated with malakoplakia reported in the bibliography. These two conditions share similar clinical signs and may probably have a common aetiopathogenesis.  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