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   2079篇
  免费   118篇
  国内免费   2篇
耳鼻咽喉   58篇
儿科学   159篇
妇产科学   23篇
基础医学   248篇
口腔科学   32篇
临床医学   271篇
内科学   411篇
皮肤病学   45篇
神经病学   276篇
特种医学   133篇
外国民族医学   5篇
外科学   152篇
综合类   13篇
预防医学   133篇
眼科学   22篇
药学   117篇
中国医学   1篇
肿瘤学   100篇
  2022年   14篇
  2021年   26篇
  2020年   21篇
  2019年   29篇
  2018年   36篇
  2017年   33篇
  2016年   22篇
  2015年   37篇
  2014年   48篇
  2013年   80篇
  2012年   83篇
  2011年   66篇
  2010年   61篇
  2009年   57篇
  2008年   66篇
  2007年   80篇
  2006年   45篇
  2005年   66篇
  2004年   59篇
  2003年   54篇
  2002年   51篇
  2001年   60篇
  2000年   75篇
  1999年   79篇
  1998年   42篇
  1997年   47篇
  1996年   46篇
  1995年   48篇
  1994年   34篇
  1993年   50篇
  1992年   43篇
  1991年   49篇
  1990年   57篇
  1989年   54篇
  1988年   47篇
  1987年   44篇
  1986年   47篇
  1985年   42篇
  1984年   36篇
  1983年   23篇
  1982年   12篇
  1981年   25篇
  1980年   12篇
  1979年   23篇
  1978年   12篇
  1977年   18篇
  1976年   20篇
  1974年   13篇
  1972年   19篇
  1970年   15篇
排序方式: 共有2199条查询结果,搜索用时 15 毫秒
1.
Cidofovir is an acyclic nucleoside phosphonate with broad-spectrum activity against DNA viruses, including human papilloma virus (HPV). However, data on the efficacy of cidofovir in an immunosuppressive setting remain contradictory. We report for the first time on the promotion of the healing of recalcitrant warts in a patient with myelodysplastic syndrome with intravenous cidofovir treatment.  相似文献   
2.
This study reports the purification and characterization of a high molecular weight human breast cancer-associated antigen identified by a previously described (1,2) murine monoclonal antibody, BCD-B4. Immunohistochemical analysis indicated that BCD-B4 recognizes an antigen expressed in an altered form on the human breast carcinoma cell line, BT-20, compared to the non-malignant human mammary epithelial cell line, HBL-100. Chemical treatments and enzymatic digestions suggested that the recognized moiety was a protein. The antigenic determinant was resistant to neuraminidase and periodate treatments but was sensitive to trypsin and proteinase K. The antigen was purified by affinity chromatography and its molecular weight, determined by SDS-PAGE analysis under non-reducing conditions, was proven to be 250 Kd. Under reducing conditions, the molecule dissociated into two polypeptides of 125 and 45 Kd, respectively. Both subunits could be isolated from normal HBL-100 and neoplastic BT-20 cellular protein extracts by affinity chromatography. The higher molecular weight subunit showed; however, qualitative and quantitative differences between the two cell lines: it was expressed in greater quantity on BT-20 cells and its molecular weight was 15 Kd higher. Both subunits could also be identified by immunoblots of BT-20 cells.  相似文献   
3.
After a brief review of the embryology, the authors present the features of the principal anomalies of the renal and infrarenal segments of the inferior vena cava.  相似文献   
4.
We report the assessment by MRI of a lumbosacral lymphomatous localization of adult T-cell leukemia/lymphoma (ATLL) with human T-cell lymphotropic virus-1 infection in an African patient. Brain MRI detected associated multifocal lesions of increased signal intensity in the subcortical white matter. These MRI abnormalities are compatible with reported necropsy findings in cases of ATLL with neurological complications.  相似文献   
5.
6.
Background Cosmetic changes are to be expected after radiotherapy for skin tumours. Objectives This study aimed to answer the questions: How frequent are cosmetic changes after soft X‐ray therapy? Do treatment parameters, tumour thickness, localization and size of the irradiated field have a major influence? Were patients irritated by the visual appearance of the irradiated field? Methods In total, 2474 examinations of 1149 irradiated fields were performed. Results Hypopigmentation was found in 64.7% of examinations more than 90 days after therapy, teleangiectases in 43.1%, erythema in 24.8%, and hyperpigmentation in 16.8%. The frequency of hypopigmentation, teleangiectases and hyperpigmentation increased with time from X‐ray exposure; more than 4 years after therapy hypopigmentation was diagnosed in 91.8% and teleangiectases in 82.2% of examinations. Total dose, the time–dose–fractionation factor (TDF), field size and dose per fraction were significantly related to the frequency of cosmetic changes. Incidence rates of cosmetic changes differed by less than 15% if different treatment conditions were compared: thicker vs. thinner tumours, larger vs. smaller fields, higher vs. lower total doses, doses per fraction, and TDF. Frequencies of hypopigmentation, teleangiectases, erythema and hyperpigmentation differed by more than 15% between some localizations on the head. Women reported irritation by the visual appearance of the irradiated field in 12.6% of 1116 interviews, and men in 4.4% of 1284 interviews. Conclusions Cosmetic changes after soft X‐ray therapy are relatively frequent. Treatment parameters, tumour thickness and field size have only a minor influence. Few patients, but more women than men, were irritated by the visual appearance of the irradiated field.  相似文献   
7.
8.
We have cloned an infectious genome of the Junonia coenia densonucleosis virus (JcDNV) into the bacterial plasmid pBR322. The viral genome could be rescued from the recombinant plasmid pBRJ by transfection of pBRJ DNA to sensitive Spodoptera littoralis larvae. pBRJ DNA produced a typical viral infection and a comparable percentage of larvae became infected following inoculation of equivalent amounts of purified virion DNA or cloned viral DNA. Virions extracted from transfected larvae were indistinguishable from wild-type (wt) virions with regard to their biophysical and biological properties. In particular, rescued virions were as infectious as wt virions and showed identical restriction profiles of their genome. In contrast, subcloning of JcDNV DNA deleted at both extremities of a sequence of ca 250 or ca 100 bp resulted in the inability of the recombinant plasmids to initiate a viral infection. These data suggest that, as for vertebrate parvoviruses, the inverted terminal repeats display essential functions in the rescue process and replicative cycle of densoviruses. This is the first report of the molecular cloning of the infectious genome from an insect parvovirus, and more generally from an invertebrate virus. pBRJ should provide an efficient tool to further define the organization of the JcDNV genome and compare it to other parvoviruses.  相似文献   
9.
We conducted 2 studies to (a) establish the usefulness of the construct of home chaos, (b) investigate its correlates, and (c) determine the validity of the Confusion, Hubbub, and Order Scale (CHAOS) used to measure the construct in each study. Study 1 relied on a sample of European American preschoolers and their mothers and Study 2 on a sample of African American school-age children and their caregivers. Home chaos was associated with less effective parental discipline; elevated behavior problems, limited attentional focusing, and reduced ability to understand and respond to social cues in children; and reduced accuracy and efficiency in a cooperative parent-child interactional task, after controlling for potential confounds. It is concluded that (a) home chaos is not a proxy for adverse social or psychological circumstances but a useful construct in its own right; (b) home chaos is associated with multiple detrimental correlates in parents and children; and (c) the CHAOS scale provides an adequate and economical measure of home confusion and disorganization that should prove useful in clinical research with diverse populations.  相似文献   
10.
A cDNA library was generated in the expression vector lambda GT11 from rat brain poly(A)+ RNAs and screened with a GAD antiserum. Two clones reacted positively. One of them was shown to express a GAD activity which was specifically trapped on anti-GAD immunogel and was inhibited by gamma-acetylenic-GABA. Blot hybridization analysis of RNAs from rat brain revealed a single 4 kilobases band. Preliminary in situ hybridizations showed numerous cells labelled by the GAD probe such as the Purkinje and stellate cells in the cerebellar cortex and the cells of the reticular thalamic nucleus.  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