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   1278685篇
  免费   92976篇
  国内免费   1997篇
耳鼻咽喉   18255篇
儿科学   42287篇
妇产科学   37857篇
基础医学   187315篇
口腔科学   35554篇
临床医学   108274篇
内科学   251996篇
皮肤病学   26535篇
神经病学   99415篇
特种医学   50010篇
外国民族医学   366篇
外科学   197740篇
综合类   26522篇
现状与发展   1篇
一般理论   300篇
预防医学   92759篇
眼科学   29107篇
药学   97946篇
  1篇
中国医学   2517篇
肿瘤学   68901篇
  2018年   11903篇
  2015年   11684篇
  2014年   16118篇
  2013年   24517篇
  2012年   33738篇
  2011年   36164篇
  2010年   21287篇
  2009年   20093篇
  2008年   35115篇
  2007年   38074篇
  2006年   38626篇
  2005年   37893篇
  2004年   36469篇
  2003年   35444篇
  2002年   34972篇
  2001年   58106篇
  2000年   59593篇
  1999年   50695篇
  1998年   14236篇
  1997年   12813篇
  1996年   13074篇
  1995年   12353篇
  1994年   11758篇
  1993年   10861篇
  1992年   40991篇
  1991年   40359篇
  1990年   39888篇
  1989年   38707篇
  1988年   36112篇
  1987年   35351篇
  1986年   33724篇
  1985年   32137篇
  1984年   23923篇
  1983年   20819篇
  1982年   12377篇
  1981年   10928篇
  1980年   10206篇
  1979年   22641篇
  1978年   15878篇
  1977年   13734篇
  1976年   12972篇
  1975年   14201篇
  1974年   16682篇
  1973年   16077篇
  1972年   15320篇
  1971年   14230篇
  1970年   13215篇
  1969年   12735篇
  1968年   11979篇
  1967年   10481篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Eleven children with Pseudomonas aeruginosa infection complicating foot puncture wounds were reviewed. Delay in presentation (mean 2 days) and diagnosis (mean 9 days) due to a paucity of clinical signs of deep infection was characteristic of this condition. Septic arthritis (5 patients) and osteomyelitis (3 patients) were frequent complications. Treatment involved multiple surgical debridements and prolonged intravenous antibiotic therapy. The clinical outcome was good although long-term radiographic changes were common.  相似文献   
993.
在蟾蜍离体坐骨神经-缝匠肌制备的肌细胞终板进行细胞内记录,研究了雌酮对神经-肌接头传递的影响。结果表明:雌酮加于浸浴液能增加10μg筒箭毒处理组和10mmol/L MgCl2处理组制备的终板电位振幅,但前者的增加更显著;雌酮加入浸浴液30分钟后引起小终板电位的振幅和频率明显增加,但波形不改变,静息膜电位也不改变。这些结果提示,雌酮能增加神经-肌接头传递,且主要通过突触前机理的作用。  相似文献   
994.
995.
The aim of this study was to evaluate the cerebral synthesis of eicosanoids in the asphyctic newborn and to investigate the relation between the prostanoid profiles in cerebrospinal fluid (CSF) and the appearance and severity of hypoxic-ischaemic encephalopathy (HIE). Levels of 6-keto-PGF 1-α, TXB2, PGE2 and PGF2-α in CSF were measured in 40 full term newborns during the first day of life. Thirty of these newborns had birth asphyxia and were divided into three groups: 10 without HIE, 12 with mild HIE and 8 with moderate-severe HIE. They were compared to a control group of 10 non-hypoxic newborns. Determinations of the metabolites in CSF were performed by RIA and expressed as pg/ml (mean ± SD). The CSF TXB2 (thromboxane A2 metabolite) in asphyxiated newborns was always higher than in the control group (28.12 ± 10.6), and related to the severity of HIE ( p = 0:005): without HIE (50.84 ± 16.4; p = 0:02), mild HIE (80.65 ± 12.64; p ± 0:01) and moderate-severe HIE (178.14 ± 20.5; p < 0:01). The CSF 6-keto-PGF 1-α (prostacyclin metabolite) in asphyxiated newborns was always higher than in the control group (80.55 ± 12.56), but indirectly related to the severity of HIE: without HIE (240.95 ± 28.12; p < 0:01), mild HIE (183.65 ± 30.1; p < 0:01) and moderate-severe HIE (140.55 ± 25.12; p < 0:01). In the moderate-severe HIE group, the increase in TXB2 was higher than the rise in 6-keto-PGF 1-α.  相似文献   
996.
997.
We report the results of administration of danazol after suspension of gonadotrophin-releasing hormone analogue (GnRHa) therapy for uterine myomas. A total of 21 women with uterine myomas was treated with 100 mg danazol for 6 months after GnRHa therapy. Uterine volume and endocrine status were monitored monthly by ultrasound and assay of plasma gonadotrophins, oestradiol and progesterone. The results show a rebound of uterine volume about 30% less than in controls at the end of danazol therapy. Menstrual cyclicity returned after 65 +/- 3 days in 16 subjects and five patients remained amenorrhoeic. Hormone assays confirmed renewed ovarian function in the women whose menstrual periods returned. Bone mineral content was substantially reduced during GnRHa treatment but improved significantly during danazol therapy even in the women who remained amenorrhoeic. These results show the utility of danazol in prolonging the therapeutic effects of GnRHa. The mechanism by which danazol inhibits rebound of uterine volume may be due to its antiprogesterone effects on uterine myomas.   相似文献   
998.
Species-level identification of Acanthamoeba isolates is difficult and gives little or no indication of the isolate's pathogenicity. We identified two amplification-based genetic markers that were highly correlated with pathogenicity in Acanthamoeba spp. One marker, designed to amplify a 485-bp fragment of the small-subunit ribosomal RNA gene (ssrDNA), was preferentially amplified from the nonpathogenic strains; amplifications from the pathogenic strains yielded anomalous fragments of 650 and 900?bp. A second marker was developed on the basis of the anomalous 650-bp fragment. Primers to this sequence preferentially amplified a noncoding locus (called Ac6) only from the pathogenic strains. These two genetic markers may be useful for identification of pathogenic Acanthamoeba spp. strains.  相似文献   
999.
Aims : Adenocarcinomas account for about 60% of metastatic cancers of unknown primary (CUP) site. In such a clinical CUP situation, histopathologists are challenged to differentiate renal cell carcinomas (RCC) from other adenocarcinomas with similar immunophenotypes, especially chemotherapeutically treatable mammary and ovarian carcinomas. Methods and results : Recently, we produced a monoclonal antibody (mAb), designated 138H11, against human gamma-glutamyltransferase (γGT), which stained over 98% primary clear cell and chromophilic RCC on frozen sections. The 138H11 epitope could not be stained using conventional techniques in most paraffin-embedded sections of the same origin, due to destruction by formalin fixation below the detection level. Here, we demonstrate that mAb 138H11 can specifically stain γGT in paraffin-embedded primary and metastatic RCC after enhancement with an ultrasensitive immunohistochemical method. We analysed a selected subgroup of adenocarcinomas with immunophenotypes which would not allow a differentiation from RCC in a CUP situation. We found a predominantly membranous expression of the 138H11 target antigen in 26/51 primary RCC and 15/34 metastatic RCC. In contrast, all 43/43 primary ovarian and bronchial carcinomas as well as 54/54 metastases of ovarian, mammary, bronchial and gastric carcinomas were negative for mAb 138H11. Conclusions : The data suggest that mAb 138H11 is useful for the immunohistochemical differentiation of RCC from other metastatic adenocarcinomas if the primary site of the tumour is not known.  相似文献   
1000.
 Immunocytochemically detectable MT and p53 have been found more commonly in comedo DCIS of the breast with high-grade cytology. The aim of this study is to confirm these findings and to investigate the relationship between MT and p53 in a single large series of cases of DCIS of the breast. To this end, 127 cases of DCIS were classified histologically according to architecture, cytonuclear differentiation (grade), presence and extent of intraduct necrosis, and using the Van Nuys system. Sections were immunostained for p53 and MT (E9) using established techniques, and the extent and intensity of staining were assessed semi-quantitively. The results confirmed that there was generally more MT and p53 positivity in poorly differentiated (grade 3) DCIS with extensive necrosis and that MT expression was greater in grade 2 lesions than p53 expression. However, overall there was no statistically significant correlation between p53 and MT staining. The results indicate that MT and p53 overexpression may arise from independent mechanisms in early breast neoplasia. Received: 3 July 1996 / Accepted: 5 November 1996  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