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   1881篇
  免费   138篇
  国内免费   9篇
耳鼻咽喉   36篇
儿科学   126篇
妇产科学   59篇
基础医学   274篇
口腔科学   26篇
临床医学   153篇
内科学   411篇
皮肤病学   45篇
神经病学   88篇
特种医学   54篇
外科学   196篇
综合类   68篇
一般理论   1篇
预防医学   98篇
眼科学   75篇
药学   145篇
中国医学   5篇
肿瘤学   168篇
  2024年   5篇
  2023年   24篇
  2022年   33篇
  2021年   93篇
  2020年   59篇
  2019年   51篇
  2018年   90篇
  2017年   51篇
  2016年   79篇
  2015年   75篇
  2014年   104篇
  2013年   92篇
  2012年   167篇
  2011年   146篇
  2010年   79篇
  2009年   60篇
  2008年   112篇
  2007年   136篇
  2006年   98篇
  2005年   90篇
  2004年   79篇
  2003年   61篇
  2002年   54篇
  2001年   14篇
  2000年   10篇
  1999年   26篇
  1998年   15篇
  1997年   11篇
  1996年   11篇
  1995年   4篇
  1994年   5篇
  1993年   4篇
  1992年   10篇
  1991年   19篇
  1990年   11篇
  1989年   10篇
  1988年   7篇
  1987年   5篇
  1986年   3篇
  1985年   4篇
  1984年   5篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
  1942年   1篇
排序方式: 共有2028条查询结果,搜索用时 328 毫秒
1.
Background Transarterial chemoemobolization (TACE) is commonly used to treat metastatic carcinoid tumors; however, the management of progressive disease is less clear. We sought to determine if patients with disease progression after TACE would benefit from repeat TACE. Methods The records of 27 patients undergoing repeat TACE for radiologic or symptomatic progression after TACE for metastatic carcinoid were reviewed and compared to 122 undergoing first TACE. Overall and progression-free survivals were estimated by the Kaplan–Meier method. Results Mean disease-free interval after first TACE was 11.8 months. Radiologic response was observed in 61% compared to 82% after first TACE (p = 0.058); hormone response in 64% compared to 80% (p = 0.159); and symptomatic response in 77% compared to 92% (p = 0.053). The complication rate after repeat TACE was lower than after first TACE (p = 0.03). Median overall survival was similar after repeat (28.1 months) and first TACE (33.3 months) (p = 0.53). Progression-free survival was shorter after repeat TACE but not significantly so. No factor examined could predict survival after repeat TACE. Conclusion Repeat TACE for patients with hepatic carcinoid metastases failing first TACE or having evidence of disease progression is safe and offers a viable treatment option. Presented at the 48th Annual Meeting of The Society for Surgery of the Alimentary Tract, Washington, DC, May, 2007.  相似文献   
2.
3.
4.
Sturge-Weber syndrome is a rare neurocutaneous disorder characterized by a facial nevus flammeus and extensive angiomatous changes involving the leptomeninges, the dura, and vessels of the gray and white matter. Oculodermal melanocytosis is characterized by hyperpigmentation of the facial skin in the distribution of the ophthalmic, maxillary, and occasionally mandibular division of the trigeminal nerve.  相似文献   
5.
PurposeNoroviruses are common viral agents in acute diarrhea in all age groups worldwide. Norovirus has been classified into 10 genogroups, GI to GX with over 48 genotypes among them the GII.4 genotype has evolved over time with a clear pattern of periodic variant replacement. Immunity is strain or genotype specific with little or no protection conferred across genogroups. The present study was aimed to determine the epidemiology, prevalent genotypes of norovirus in children below five years of age in the Hyderabad region, India.MethodsThe stool samples and clinical data were collected from 458 children below 5 years of age comprising of cases with acute gastroenteritis (n ?= ?366) and a control group (n ?= ?92) admitted to the pediatric ward. All the samples were tested for Norovirus by ELISA and RT-PCR. Sequencing was done for predominant strains.Results10.3% (n ?= ?38) of cases and 3.2% (n ?= ?3) of the control group were found to be Norovirus positive. Predominant genotypes were GII-82.5% followed by GI-12.5%.ConclusionSequencing and Phylogenetic analyses of 20 GII.4 strains was done. All of the isolates are clustered away from published the GII.4 variants thus suggesting the appearance of a new variant.  相似文献   
6.
We recently reported that a chimeric simian/human immunodeficiency virus (SHIVKU-1) developed in our laboratory caused progressive depletion of CD4+T lymphocytes and AIDS within 6 months of inoculation into pig-tailed macaques (M.nemestrina). None of the pig-tailed macaques showed productive SHIV infection in the central nervous system (CNS). In this report, we show that by further passage of the pathogenic virus in rhesus macaques [M. mulatta], we have derived a new strain of SHIV (SHIVKU-2) that has caused AIDS and productive CNS infection in 3 of 5 rhesus macaques infected with the virus. Productive replication of SHIV in the CNS was clearly shown by high infectivity titers and p27 protein levels in brain homogenates, and in 2 of the 3 rhesus macaques this was associated with disseminated, nodular, demyelinating lesions, including focal multinucleated giant cell reaction, largely confined to the white matter. These findings were reminiscent of HIV-1 associated neurological disease, and our immunohistochemical and in situ hybridization data indicated that the neuropathological lesions were associated with the presence of SHIV-specific viral antigens and nucleic acid respectively. However, the concomitant reactivation of opportunistic infections in these macaques suggested that such pathogens may have influenced the replication of SHIV in the CNS, or modified the neuropathological sequelae of SHIV infection in the rhesus species, but not in pig-tailed macaques. Our findings in the two species of macaques highlight the complexities of lentiviral neuropathogenesis, the precise mechanisms of which are still elusive.  相似文献   
7.
Kamath S  Sahni S  Ranka S  Li J  Palta J 《Medical physics》2004,31(12):3314-3323
The multileaf travel range limitations on some linear accelerators require the splitting of a large intensity-modulated field into two or more adjacent abutting intensity-modulated subfields. The abutting subfields are then delivered as separate treatment fields. This workaround not only increases the treatment delivery time but it also increases the total monitor units (MU) delivered to the patient for a given prescribed dose. It is imperative that the cumulative intensity map of the subfields is exactly the same as the intensity map of the large field generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. In this work, we describe field splitting algorithms that split a large intensity-modulated field into two or more intensity-modulated subfields with and without feathering, with optimal MU efficiency while satisfying the hardware constraints. Compared to a field splitting technique (without feathering) used in a commercial planning system, our field splitting algorithm (without feathering) shows a decrease in total MU of up to 26% on clinical cases and up to 63% on synthetic cases.  相似文献   
8.
Branches of the splenic artery and splenic arterial segments   总被引:2,自引:0,他引:2  
In 200 adult autopsy specimens, the arterial supply to the pancreas and spleen was studied radiologically and by manual dissection. The splenic artery divided into two or three lobar arteries, which supplied its corresponding lobe; each lobar artery subsequently divided into two to four lobular branches. Six to twelve lobular branches were observed entering the splenic substance at the hilum. Lobar arteries did not anastomose with each other, hence, the lobes of the spleen are also termed segments. The lobules, however, were not found to be independent segments and the arteries of one lobule anastomosed with those of other lobules. The branching pattern of the splenic artery varied from one specimen to another, so much so that a prevailing pattern could not be identified. Polar arteries, particularly to the superior pole, arose quite proximal to the hilum in 51% of cases and were occasionally missed. In 45% of males and 40% of females, the posterior gastric artery arose from about the middle of the splenic artery. The splenic artery was not found to be tortuous in fetuses, newborns, and young children. Tortuosity was seen in only 10% of adults; thus, the characteristic tortuosity of the splenic artery appears to develop with age.  相似文献   
9.
10.
Hematological profile of HIV positive patients   总被引:4,自引:0,他引:4  
A series of 500 HIV positive patients referred to our centre for CD4 and CD8 cell enumeration are included in this study. The following parameters were studied in each of these patients: Hb, RBC indicates, WBC count, platelet count, three part differential count, absolute CD4 and CD8 counts. Male:Female ratio of 4.9:1 was noted 30.8% patients has anemia (Hb<10 gm%), with an average Hb value of 8.1 gm%. The anemia was normochromic, normocytic in 61% of patients, microcytic in 33% and macrocytic in 6% patients. The absolute CD4 count was less than 200 ul in 50.2% patients with an average value of 92/ul. Thrombocytopenia was seen in 13% patients with average platelet count 0.92x10(3)/ul.  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