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   1840篇
  免费   110篇
  国内免费   4篇
耳鼻咽喉   14篇
儿科学   40篇
妇产科学   92篇
基础医学   264篇
口腔科学   34篇
临床医学   154篇
内科学   578篇
皮肤病学   49篇
神经病学   153篇
特种医学   44篇
外科学   194篇
预防医学   109篇
眼科学   6篇
药学   113篇
肿瘤学   110篇
  2023年   12篇
  2022年   9篇
  2021年   41篇
  2020年   16篇
  2019年   31篇
  2018年   42篇
  2017年   28篇
  2016年   33篇
  2015年   36篇
  2014年   52篇
  2013年   65篇
  2012年   117篇
  2011年   121篇
  2010年   62篇
  2009年   74篇
  2008年   120篇
  2007年   121篇
  2006年   129篇
  2005年   123篇
  2004年   100篇
  2003年   89篇
  2002年   92篇
  2001年   45篇
  2000年   37篇
  1999年   31篇
  1998年   24篇
  1997年   15篇
  1996年   19篇
  1995年   10篇
  1994年   12篇
  1993年   13篇
  1992年   25篇
  1991年   26篇
  1990年   17篇
  1989年   13篇
  1988年   20篇
  1987年   17篇
  1986年   12篇
  1985年   18篇
  1984年   12篇
  1983年   16篇
  1982年   9篇
  1981年   6篇
  1980年   8篇
  1979年   5篇
  1977年   3篇
  1975年   3篇
  1971年   3篇
  1966年   3篇
  1896年   2篇
排序方式: 共有1954条查询结果,搜索用时 31 毫秒
1.
Problem reporting rates of 180 persons with cancer (PWC) were compared with those of their closest in age same sex cancer-free siblings living outside their households for the same time periods. PWC had significantly higher reporting rates for physical, activities of daily living, nutrition, and emotional problems and a significantly lower rate for family problems. Sibling problem reporting rates, which indicate the likelihood that PWC would have experienced similar problems without a diagnosis of cancer, were highest for physical, emotional, employment, and family problems suggesting that noncancer factors are especially likely to play a role in those types of problems. Regression analyses showed that female and younger PWCs tended to report more problems than their siblings suggesting that they were more affected by cancer and its treatments than were other types of PWC.  相似文献   
2.
The distribution of blood flow in skeletal muscle stimulated to rhythmic isotonic contractions was studied by injections of radioactive microspheres into the arterial supply in 8 gastrocnemius muscles (mean weight 84 g) of 6 anesthetized dogs (20-25 kg body weight). The distribution of 10 micron microspheres in regions of about 0.5 g was very similar to that of the standard 15 micron microspheres, whereas that of 25 micron microspheres was more uneven. The coefficient of variation (CV = SD/mean) of the ratio of simultaneously injected 10 micron and 15 micron microspheres, 0.12, was taken as the inherent scatter of the method. The average spatial distribution inequality of 10-15 micron microspheres corresponded to a CV of 0.45 and the specific local blood flow inhomogeneity to a CV = 0.43 ( = square root 0.45(2) - 0.12(2], but there were marked differences between muscles. At equal blood flow levels, the inhomogeneity during reactive hyperemia was similar to that observed during stimulation. The temporal variability of blood flow in individual muscle pieces was obtained from the comparison of fractional trapping of 4 to 5 differently labeled microspheres injected at intervals of 2 min into steadily stimulated muscles. The mean CV for the variations in time was 0.23 and that corrected for methodological scatter, 0.19, but the differences in the extent of temporal blood flow changes among muscle pieces within a muscle and between different muscles were large. The presence of considerable spatial and temporal variations of blood flow in exercising muscle during apparent steady state may be important in limiting and/or modulating tissue O2 supply.  相似文献   
3.
Stapled hemorrhoidopexy is widely accepted to treat hemorrhoids, but serious complications have been reported. In this prospective audit, we correlated clinical outcome with pathological findings. From January 2003 to April 2007, 94 patients underwent hemorrhoidopexy. Macroscopic appearance of the specimen (shape, size, and depth) was recorded. Microscopically, the presence of columnar, transitional, and squamous epithelium, the involvement of circular/longitudinal smooth muscle, and features of mucosal prolapse were assessed. Clinical outcome was evaluated by a validated questionnaire. Postoperative pain, secretion, and bleeding durations were 12.7 +/− 10.6, 5.6 +/− 9.6, and 6.3 +/− 8.4 days. Patient’s return to work averaged 16.7 +/− 10.7 days. Fissure, skin tags, and anal strictures were observed in 23.4%. Seven patients experienced pain for a significantly longer period of time. All specimens contained columnar mucosa, but 29.8% contained columnar and transitional epithelium and 12.8% contained columnar, anal transitional, and stratified squamous epithelium. Smooth muscle was observed in 62.7%. Pain was significantly increased if transitional epithelium was present in the specimen. No correlation or differences were observed if smooth muscle was present, although postoperative bleeding was more frequent. Hemorrhoidopexy is safe and effective. The specimen should always be sent for pathology examination. Only columnar epithelium should be present and, although the presence of smooth muscle does not influence the outcome in terms of functional results, its presence may play a role in postoperative bleeding. Presented as poster at the Digestive Disease Week, May 2007, Washington, USA  相似文献   
4.
Background Recently, it has been demonstrated that surgical treatment of hemorrhoids in a day-care basis is possible and safe. The aim of this study was to compare the Longo stapled hemorrhoidopexy (SH) and the Milligan–Morgan hemorrhoidectomy (MMH). Methods One hundred seventy one patients (95 cases in SH group and 76 cases in MMH group) entered the study: 83 cases were III degree hemorrhoids, 88 IV degree. A priori and a post hoc power analysis were performed. Results, prospectively collected, were compared using chi squared test and student t test. Visual analog scale was used for pain evaluation. Postoperative pain, duration of pain, wound secretion, bleeding, resumption of a normal lifestyle, and postoperative complication were evaluated. Results Surgical time was 28.41 ± 10.78 for MMH and 28.30 ± 13.28 min in SH (P = 0.94). Postoperative pain was not different between MMH and SH during the first two postoperative days (4.73 ± 2.91 vs 5.1 ± 3.048; P = 0.4), during the following 6 days, patients treated with SH had less pain (4.63 ± 2.04 in MMH vs 3.60 ± 2.35 in SH; P = 0.006). In the SH group, seven patients needed further hospital stay for complicated course. SH showed higher incidence of anal fissure compared with MMH (6.3% vs 0%; P = 0.025) but no differences in urinary retention, anal stricture, urgency, or anal hemorrhage. Conclusions This study confirms that SH is associated with less postoperative pain and shorter postoperative symptoms, compared with MMH. SH may be a viable addition to the therapy for hemorrhoids with some advantages in early postoperative pain and some disadvantages in postoperative complications and costs.  相似文献   
5.
We report the collaboration between the First Postgraduate School of Obstetrics and Gynecology at the University of Milan, Italy, and the nongovernmental organization “Emergency” that operates through its own hospitals in countries devastated by armed conflicts. The collaboration was centered on the maternity clinic that Emergency opened in 2003 in northern Afghanistan. After a woman resident spent 5 months on-site, the collaboration is now extended to all residents with a group with four areas of intervention: guidelines, clinical records and data collection, drugs and medical devices, and teaching material. In addition, it offers consultation by e-mail for any clinical issue that might arise.  相似文献   
6.
In this study, a replicative fowl adenovirus serotype 1 (CELO) recombinant expressing chicken interferon-gamma (ChIFN-gamma) was constructed. In the engineered recombinant, the ChIFN-gamma gene was placed under the control of cytomegalovirus (CMV) promoter. The ChIFN-gamma expression cassette was inserted in the right end of the CELO genome (D fragment), which was able to carry the largest insertion of foreign DNA without affecting the replication functions of the vector. The recombinant ChIFN-gamma (rChIFN-gamma) produced in the CELO-virus expression system was characterized by comparing its biologic activities with that of rChIFN-gamma produced via the baculovirus expression system (Bac-ChIFN-gamma). CELO-ChIFN-gamma inhibited the replication of cytolytic virus in chicken embryo fibroblasts (CEFs) and activated macrophages in a better manner than did Bac-ChIFN-gamma . Moreover, the in vitro and in vivo stability of the CELO-derived rChIFN-gamma was considerably higher than that of the Bac-ChIFN-gamma. The CELO-ChIFN-gamma recombinant vector was able to replicate in vitro in the loghorn male hepatoma (LMH) hepatocyte cell line and to produce detectable levels of recombinant cytokine in supernatant as early as 90 min post-infection. Therefore, the CELO-virus expression system is an appropriate system for high-level expression of biologically active and stable ChIFN-gamma.  相似文献   
7.
Summary An epidemiological survey of hereditary ataxias and paraplegias was conducted in Molise, a region of Italy (335, 211 inhabitants on 1 January 1989). Total prevalence was 7.5 x 10–5 inhabitants (95% confidence limits 4.8–11.1). There were 7 patients with Friedreich's disease, 5 with early onset cerebellar ataxia with retained tendon reflexes, 4 with ataxia-telangiectasia, 9 with hereditary spastic paraplegias (2 autosomal dominant and 7 autosomal recessive cases). There was no patient with autosomal dominant cerebellar ataxia.  相似文献   
8.
Immune evasion by Lyme spirochetes is a multifactorial process involving numerous mechanisms. The OspE protein family undergoes antigenic variation during infection and binds factor H (fH) and possibly FHL-1/reconectin. In Borrelia burgdorferi B31MI, the OspE family consists of three paralogs: BBL39 (ErpA), BBP38, and BBN38 (ErpP). BBL39 and BBP38 are identical and therefore are referred to here as BBL39. The goals of this study were to assess the specificity of the antibody (Ab) response to the OspE paralogs and to identify the domains or determinants of OspE that are required for the binding of fH and OspE-targeting Abs that develop during infection. Here we demonstrate that at least some of the anti-OspE Abs produced during infection are paralog specific and that Ab binding requires conformational determinants whose formation requires both the N- and C-terminal domains of OspE. The binding of fH to OspE was also found to be dependent on conformational determinants. It is also demonstrated here that all of the OspE paralogs expressed by B. burgdorferi B31MI are capable of binding fH. The binding of fH to members of the OspF protein family was also assessed. In contrast to an earlier report, no binding of BBO39 or BBR42 to human fH was detected. Lastly, a series of competitive binding enzyme-linked immunosorbent assay analyses, designed to determine if fH and infection serum Abs bind to the same sites on OspE, revealed that these ligands interact with different regions of OspE.  相似文献   
9.
The limb-girdle muscular dystrophies are a clinically and geneticallyheterogeneous group of disorders. We have ostudied two largeinbred families of different ethnic origin and excluded linkageto LGMD2 on chromosome 15q and SCARMD on chromosome 13. Proceedingto a genomic linkage search, we have now identified linkageto markers D2S134 and D2S136 on chromosome 2p (maximum lod score3.57 at zero recombination). The phenotype in the two familieswas similar, with onset in the pelvic girdle musculature inthe late teens and usually relatively slow progression. Thiswork Identifies a second locus for autosomal recessive limb-girdlemuscular dystrophy.  相似文献   
10.
Treponema denticola is an important contributor to periodontal disease. In this study we investigated the ability of T. denticola to bind the complement regulatory proteins factor H and factor H-like protein 1 (FHL-1). The binding of these proteins has been demonstrated to facilitate evasion of the alternative complement cascade and/or to play a role in adherence and invasion. Here we demonstrate that T. denticola specifically binds FHL-1 via a 14-kDa, surface-exposed protein that we designated FhbB. Consistent with its FHL-1 binding specificity, FhbB binds only to factor H recombinant fragments spanning short consensus repeats (SCRs) 1 to 7 (H7 construct) and not to SCR constructs spanning SCRs 8 to 15 and 16 to 20. Binding of H7 to FhbB was inhibited by heparin. The specific involvement of SCR 7 in the interaction was demonstrated using an H7 mutant (H7AB) in which specific charged residues in SCR 7 were replaced by alanine. This construct lost FhbB binding ability. Analyses of the ability of FHL-1 bound to the surface of T. denticola to serve as a cofactor for factor I-mediated cleavage of C3b revealed that C3b is cleaved in an FHL-1/factor I-independent manner, perhaps by an unidentified protease. Based on the data presented here, we hypothesize that the primary function of FHL-1 binding by T. denticola might be to facilitate adherence to FHL-1 present on anchorage-dependent cells and in the extracellular matrix.  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