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   877篇
  免费   39篇
  国内免费   12篇
耳鼻咽喉   10篇
儿科学   27篇
妇产科学   35篇
基础医学   117篇
口腔科学   6篇
临床医学   76篇
内科学   188篇
皮肤病学   68篇
神经病学   73篇
特种医学   41篇
外科学   72篇
综合类   14篇
一般理论   5篇
预防医学   45篇
眼科学   19篇
药学   78篇
中国医学   2篇
肿瘤学   52篇
  2023年   7篇
  2022年   10篇
  2021年   17篇
  2020年   8篇
  2019年   12篇
  2018年   20篇
  2017年   13篇
  2016年   21篇
  2015年   23篇
  2014年   37篇
  2013年   52篇
  2012年   42篇
  2011年   55篇
  2010年   41篇
  2009年   24篇
  2008年   52篇
  2007年   44篇
  2006年   58篇
  2005年   63篇
  2004年   44篇
  2003年   40篇
  2002年   43篇
  2001年   6篇
  2000年   9篇
  1999年   13篇
  1998年   13篇
  1997年   6篇
  1996年   4篇
  1995年   5篇
  1994年   9篇
  1993年   5篇
  1992年   7篇
  1991年   10篇
  1990年   11篇
  1989年   15篇
  1988年   11篇
  1987年   4篇
  1985年   11篇
  1984年   5篇
  1983年   5篇
  1981年   3篇
  1979年   6篇
  1977年   4篇
  1976年   5篇
  1975年   3篇
  1974年   2篇
  1973年   3篇
  1971年   2篇
  1967年   2篇
  1965年   3篇
排序方式: 共有928条查询结果,搜索用时 15 毫秒
51.
INTRODUCTION: The possibilities and limitations of fibrin glue (FG) usage in nephron-sparing surgery were studied. MATERIALS AND METHODS: A prospective experimental study was carried out in 50 pigs: 30 with polar resection, and 20 with mediorenal wedge resection of the kidney. Hemostatic sutures, FG, and FG with a muscle 'cup' in animals with polar resection of the kidney were compared. FG and sutures in animals with the wedge resection of the kidney were studied as well. Bleeding, hot ischemia time, complication rate, and additional scarring were also analyzed. RESULTS: Suture hemostasis is safe but with significant adverse effects in both polar and wedge resection of kidney. FG was not efficient as a sole hemostatic agent for polar resection. It was as efficient as hemostatic suture for wedge resection of the kidney. FG with a muscle 'cup' on a pole of the kidney achieved good results in animals with polar resection of the kidney. Histological analysis confirmed better results with FG because of both the less intense and smaller area of additional scarring. CONCLUSION: FG is a reliable and efficient hemostatic agent for nephron-sparing surgery whenever both sided gluing is possible.  相似文献   
52.
PURPOSE: We determined if vaccinia virus (VV) mediated delivery of human tumor suppressor p53 is safe and effective for bladder tumor therapy in an orthotopic murine model. MATERIALS AND METHODS: We used recombinant VV (rVV) vectors to express transgenes in murine bladder cancer MB-49 cells in culture and those growing orthotopically in syngeneic mice. Cultured MB-49 cells were infected with rVV expressing reporter genes (rVV-L15) or p53 (rVV-TK-53) to measure virus infection and apoptosis induction. Orthotopic MB-49 tumors in C57/Bl6 mice were treated with intravesical instillation of rVV, and the tumor incidence, survival and transgene expression were determined. RESULTS: Productive virus infection in vitro was observed in MB-49 cells, although at somewhat lower efficiency than in African Green Monkey kidney CV-1 cells (American Type Culture Collection, Manassas, Virginia). Expression of transgenes in vitro correlated with the virus dose. Cells infected with rVV underwent apoptosis with rVV-TK-53 inducing far greater cell death than rVV-L15. The rVV-L15 virus had no effect on tumor incidence but it increased mean survival compared with control. Instillation of rVV-TK-53 decreased the tumor incidence and 33% of mice survived treatment. At necropsy all nonsurviving mice had bladder tumor, whereas 2 survivors in the rVV-TK-53 treated group were tumor-free. Immunohistochemistry of tumors detected expression of the human p53 gene product in tumor cells. CONCLUSIONS: To our knowledge we report for the first time that recombinant vaccinia virus expressing human p53 can induce the death of MB-49 tumor cells in vivo, not only through the lytic effect of the virus, but also through expression of the death inducing p53 transgene. Further studies are needed to shed light on the mechanisms of rVV-TK-53 mediated tumor apoptosis and the antitumor immune response.  相似文献   
53.
A splice variant of cyclooxygenase-1 (COX-1), COX-1b (previously termed as COX-3), has been identified in canine tissues as an acetaminophen-sensitive isoform, but the sequence of COX-1b mRNA and the encoded protein are not known in rats. We cloned and sequenced rat COX-1b mRNA from cerebral endothelial cells. Sequence analysis indicated that the 98-base pair intron-1 of COX-1 gene remains unprocessed in the COX-1b mRNA, causing a frameshift mutation and a 127-amino acid open reading frame with no sequence similarity with known cyclooxygenases. Transient and permanent transfection of COS-7 cells with a vector containing the rat COX-1b cDNA resulted in synthesis of a protein of the expected size. We generated an affinity-purified polyclonal antibody against the rat COX-1b protein. Western blot analysis of rat tissues using this antibody demonstrated the likely existence of rat COX-1b protein in vivo with the highest expression in heart, kidney, and neuronal tissues. Our results on both stable and on transiently transfected COS-7 cells suggest that rat COX-1b does not have cyclooxygenase activity and does not have any effect on the inhibition of prostaglandin production by acetaminophen. Because this protein has a completely different amino acid sequence than COX-1 and COX-2 and it does not have cyclooxygenase activity, we suggest a name cyclooxygenase variant protein to distinguish it from the known prostaglandin-synthesizing cyclooxygenase isoforms.  相似文献   
54.
55.
OBJECTIVES: The aim of this study was to better understand suicides in children and adolescents using records from the Office of the Medical Examiner of Virginia from 1987 to 2003. MAIN FINDINGS, KEY DATA, AND STATISTICS: Suicide accounted for 16.8% of unnatural deaths. Suicide rates were highest for Caucasians. Guns were the most common method of death for suicides, followed by hanging and poisoning. Poisoning other than carbon monoxide accounted for 7.8% of suicides, with tricyclic antidepressants (TCAs) the most identifiable poison. Female youths were 10 times more likely to die from TCAs than male youths, after adjusting for race and age. CONCLUSIONS: Guns and hanging were the principal methods of suicide. Among the antidepressants, TCAs have been the most common poisons used in suicide. Increasing age was a powerful determinant of suicide. Some patients may have stockpiled their TCAs for a while before their TCA overdose. Other suicide victims may have used TCA supplies from family members. Hence, some of the suicide victims may not have taken TCAs on a regular basis before committing suicide. Further exploration of TCA-induced suicidal thoughts is needed. Conclusions cannot be made at the time about the precise role that TCAs played in TCA-induced suicide reported in our study.  相似文献   
56.
INTRODUCTION: Obesity is a major problem among children and adolescents suffering from chronic mental illness. State-of-the-art measures such as body mass index (BMI) and growth-related weight charts are now readily available to clinicians and investigators interested in psychotropic drug-associated weight gain in the pediatric population. However, no reports that utilize such measures in large series of children and adolescents with psychiatric disorders are available. METHODS: The authors employed the Nutstat module of the Centers for Disease Control and Prevention (CDC) Epi Info software to assess BMI in a psychiatry inpatient child and adolescent population in Central Virginia. The authors also developed a scoring system to relate psychotropic administration to BMI. RESULTS: Children and adolescents with chronic mental illness had greater BMI measurements than the general pediatric population. Our scoring system found a relationship between antipsychotic drug administration and increased BMI that almost reached a level of significance (p=0.062). CONCLUSIONS: The present methodology using absolute weight to assess psychotropic drug-associated increase in body weight for children and adolescents is unsatisfactory. The authors offer a new and convenient methodology to correct this problem.  相似文献   
57.
Srinath Reddy K  Shah B  Varghese C  Ramadoss A 《Lancet》2005,366(9498):1744-1749
At the present stage of India's health transition, chronic diseases contribute to an estimated 53% of deaths and 44% of disability-adjusted life-years lost. Cardiovascular diseases and diabetes are highly prevalent in urban areas. Tobacco-related cancers account for a large proportion of all cancers. Tobacco consumption, in diverse smoked and smokeless forms, is common, especially among the poor and rural population segments. Hypertension and dyslipidaemia, although common, are inadequately detected and treated. Demographic and socioeconomic factors are hastening the health transition, with sharp escalation of chronic disease burdens expected over the next 20 years. A national cancer control programme, initiated in 1975, has established 13 registries and increased the capacity for treatment. A comprehensive law for tobacco control was enacted in 2003. An integrated national programme for the prevention and control of cardiovascular diseases and diabetes is under development. There is a need to increase resource allocation, coordinate multisectoral policy interventions, and enhance the engagement of the health system in activities related to chronic disease prevention and control.  相似文献   
58.
"Flat" colorectal adenomas and adenocarcinomas are well documented in the Japanese literature but only sporadically reported in the English literature. The present study involved systematic morphological analysis of a large series of colorectal carcinomas (CRCs) to determine the frequency of these "flat" CRCs (FCRCs) and analyze their pathological characteristics and associated patient survival. The study group comprised 47 patients (19 females and 28 males) with primary CRC who underwent colorectal resection at the H. Lee Moffitt Cancer Center between 1997 and 2002. These cases were selected based on the gross appearance of the tumors and after review of all of the hematoxylin and eosin-stained tumor sections in a series of 190 consecutive colorectal resections for CRCs. Application of strict morphological criteria classified 22 tumors as FCRCs. For comparison, 25 "polypoid" CRCs (PCRCs) were also identified. Cases of ulcerative fungating annular CRCs and CRCs with mixed gross appearance were excluded from this analysis. Clinicopathologic data, including patient survival, were compared for FCRCS and PCRCs. Statistical analyses were carried out using the chi(2) or Fisher's exact test and log-rank tests. Overall, 22 of 190 CRCs (11%) were found to meet the morphological criteria of FCRCs. Mean patient age was 70.6 years (range, 55 to 87) for FCRCs versus 68.5 years (range, 54 to 91) for PCRCs, and mean tumor size was 4.7 cm (range, 1.6 to 9) for FCRCs versus 4.4 cm (range, 0.5 to 10) for PCRCs. None of the 22 FCRCs and only 1 of 25 (4%) PCRCs were well differentiated; 17 of 22 (77%) FCRCs and 23 of 25 (92%) PCRCs were moderately differentiated; and 5 of 22 (22%) FCRCs and 1 of 25 (4%) PCRCs were poorly differentiated (P = 0.0087). FCRC cases were staged as 0 stage T1, 3 (14%) stage T2, and 19 (86%) stage T3; PCRC cases, as 4 (16%) stage T1, 14 (56%) stage T2, and 7 (28%) stage 3 (P = 0.000031). Similarly, angiolymphatic invasion was identified in 12 of 22 (54%) FCRCs versus 4 of 25 (16%) PCRCs (P = 0.0123). Although some differences between FCRCs and PCRCs were observed on resection in terms of nodal status (N), presence of metastases (M), and perineural invasion, these differences were not statistically significant. In comparison with PCRCs, FCRCs were associated with significantly shorter postresection patient survival at 1 to 5 years (P = 0.028). We have demonstrated in this report that a proportion of primary CRCs resected at our institution were indeed "flat." Furthermore, these FCRCs exhibited higher histological grades, higher T stage, more frequent angiolymphatic invasion, and shorter patient survival compared with PCRCs. Based on these data, FCRC appears to be a worse subtype of colon cancer than PCRC. Further appraisal of FCRCs and additional studies to further elucidate the molecular mechanisms underlying their morphogenesis are warranted.  相似文献   
59.
The apoptosis-inducing activity of concentrated sediments of disinfected and non-disinfected water samples from the waterworks in Budapest, Hungary, was investigated using cultures of human peripherial blood lymphocytes. Chlorine-treated water and untreated (raw) water sediments were concentrated with the use of Amberlite XAD-2 resin columns. The concentrates were dissolved in dimethyl sulfoxide and added to cultures of human peripherial blood lymphocytes. Apoptotic index was determined in lymphocytes after treatment with the raw or disinfected concentrates by flow cytometry. Disinfected water concentrates of 100 microl/ml increased the apoptotic ratio of lymphocyte culture. The same amount of raw water concentrate also enhanced apoptosis. Both raw water and disinfected water contain substances that induced a significant rate of apoptosis in lymphocyte cultures.  相似文献   
60.
Verma B  Daga SR  Sawant D 《Indian pediatrics》2003,40(11):1081-1083
Leptospirosis has a broad spectrum of clinical manifestations varying, from inapparent influenza like illness to fulminant fatal disease with hepato-renal dysfunction and hemorrhagic phenomena. Our cases had fever, puffiness, respiratory distress and bleeding diathesis as leading manifestations. Leptospirosis was suspected in view of epidemic situation prevailing in the city. We report four cases here, three of which survived and one died.  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