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   1012篇
  免费   70篇
  国内免费   10篇
耳鼻咽喉   9篇
儿科学   57篇
妇产科学   38篇
基础医学   107篇
口腔科学   25篇
临床医学   102篇
内科学   269篇
皮肤病学   27篇
神经病学   36篇
特种医学   43篇
外国民族医学   1篇
外科学   116篇
综合类   27篇
预防医学   47篇
眼科学   35篇
药学   88篇
中国医学   3篇
肿瘤学   62篇
  2024年   2篇
  2023年   16篇
  2022年   41篇
  2021年   72篇
  2020年   59篇
  2019年   55篇
  2018年   63篇
  2017年   48篇
  2016年   42篇
  2015年   31篇
  2014年   48篇
  2013年   71篇
  2012年   90篇
  2011年   67篇
  2010年   36篇
  2009年   35篇
  2008年   39篇
  2007年   46篇
  2006年   38篇
  2005年   27篇
  2004年   20篇
  2003年   24篇
  2002年   17篇
  2001年   19篇
  2000年   13篇
  1999年   6篇
  1998年   5篇
  1997年   2篇
  1992年   4篇
  1990年   3篇
  1989年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1981年   1篇
  1979年   4篇
  1978年   2篇
  1977年   1篇
  1976年   5篇
  1975年   2篇
  1974年   1篇
  1973年   3篇
  1972年   3篇
  1971年   4篇
  1970年   3篇
  1969年   3篇
  1968年   4篇
  1967年   7篇
  1966年   1篇
  1964年   1篇
排序方式: 共有1092条查询结果,搜索用时 31 毫秒
1.
Dysgerminoma is a rare germ cell tumor of the ovary. It constitutes about 0.5% of all ovarian malignancies. During a 12-year period (1978-1989), 22 patients were treated at the National Cancer Institute, Cairo, Egypt. According to the FIGO classification system, 4 patients were allocated to Stage I, 2 were Stage II, 13 were Stage III, and 3 were Stage IV. The 5-year actuarial survival rate for all patients was 76%. Conservative treatment in addition to retrieval therapy upon recurrence could achieve 100% survival rate in Stage I patients. Surgery followed by irradiation resulted in a 66% 5-year actuarial survival rate in Stage III and 67% in Stage IV. Retroperitoneal lymph nodes seemed to have a better survival than peritoneal tumor extension. The adoption of an elective irradiation policy to the mediastinum and supraclavicular area seemed to have a good influence on prognosis. However, the extent of surgery performed could not be shown to affect survival.  相似文献   
2.
Venous thrombosis is rare in children. It can be either acquired or of constitutional origin. Thrombosis during non-Hodgkin lymphoma remains exceptional and is usually locally associated to the tumoral process, raising the issue of its tumoral or cruoric nature. The treatment is based on anticoagulation concomitantly to chemotherapy. We report on a 4-year-old boy admitted for mediastinal non-Hodgkin lymphoma, who developed a thrombosis of the superior vena cava associated to protein S-deficiency. The mechanism of thrombosis may have been multifactorial: associated protein S-deficiency, vascular compression, tumoral process and chemotherapy.  相似文献   
3.
The WIMSD4 code was used to calculate the fast neutron flux spectrum and the fast neutron fission cross-sections for (238)U, using six energy groups ranging from 0.5 to 10 MeV. These results, with the measured radioactivities of the (140)Ba, (131)I, (103)Ru, (95)Zr and (97)Zr fission products emerging from the fission of the (238)U foil covered with a cadmium filter, were used to measure the fast neutron flux in the Syrian Miniature Neutron Source Reactor inner irradiation site.  相似文献   
4.
Francisella tularensis, the causative agent of tularemia, is a highly infectious gram-negative coccobacillus. Due to its high infectivity it is of major concern to public health officials as a possible biological weapon. Although accidental exposure can occur through arthropod bites, handling infected animals, or breathing in aerosols, cases are usually isolated and contained. In the event of an intentional exposure such as in a bioterrorist attack, inhalation of aerosols can result in devastating consequences with much causality. Although a vaccine is available, sufficient quantities may not be readily accessible in an actual attack. Therefore, it is very important for both medical professionals and public health officials to be prepared to contain and control the situation should it actually occur.  相似文献   
5.
6.
Little is known about hepatitis C virus (HCV) breakthrough during antiviral therapy, although it would help in understanding HCV resistance to current antiviral treatments. To analyse the implication of virological factors and the vigour of humoral immune responses in this phenomenon, we studied nine chronic hepatitis C patients with a viral breakthrough during IFN/ribavirin combination therapy, as well as five responders and five non-responders. The IRES and regions coding for the capsid protein, the PePHD domain of envelope glycoprotein E2 and the NS5A and 5B proteins were amplified by RT-PCR before treatment, before and during breakthrough, and after treatment. The major variant sequence was obtained by direct sequencing. The heterogeneity of quasispecies was studied by SSCP in all patients and sequencing after cloning in seven genotype 1b-infected patients. Humoral responses against HCV epitopes were also analysed. The major sequences of IRES, PePHD, and NS5B remained stable during treatment, regardless of the treatment response. However, the capsid protein and the regions flanking PePHD showed sequence variations in breakthrough patients, although no specific mutation was identified. The variable V3 region of NS5A, but not the PKR-binding domain and the ISDR, seemed to be associated with differences in response to treatment. The analysis of HCV quasispecies revealed no characteristic pattern during treatment in breakthrough patients, whose HCV genome profiles looked most similar to that of non-responders. The humoral response was similar between groups. In conclusion, viral breakthrough does not seem to be due to selection of resistant strains with signature mutations.  相似文献   
7.
Retinoblastoma is an ocular tumor that occurs in young children, in either heritable or sporadic manner. The relative rarity of retinoblastoma, and the need for expensive equipment, anesthesia, and pediatric ophthalmologic expertise, are barriers for effective treatment in developing countries. Also, with an average age‐adjusted incidence of two to five cases per million children, patient number limits development of local expertise in countries with small populations. Lebanon is a small country with a population of approximately 4.5 million. In 2012, a comprehensive retinoblastoma program was formalized at the Children's Cancer Institute (CCI) at the American University of Beirut Medical Center, and resources were allocated for efficient interdisciplinary coordination to attract patients from neighboring countries such as Syria and Iraq, where such specialized therapy is also lacking. Through this program, care was coordinated across hospitals and borders such that patients would receive scheduled chemotherapy at their institution, and monthly retinal examinations and focal laser therapy at the CCI in Lebanon. Our results show the feasibility of successful collaboration across borders, with excellent patient and physician adherence to treatment plans. This was accompanied by an increase in patient referrals, which enables continued expertise development. However, the majority of patients presented with advanced intraocular disease, necessitating enucleation in 90% of eyes in unilateral cases, and more than 50% of eyes in bilateral cases. Future efforts need to focus on expanding the program that reaches to additional hospitals in both countries, and promoting early diagnosis, for further improvement of globe salvage rates.  相似文献   
8.
Nickel (Ni+2) accumulation in wastewater treatment sludge poses a potential environmental risk with biosolids-land application. An incubation experiment was conducted to evaluate the effect of nanoparticles of zero-valent iron (nZVI) on Ni+2 sorption in biosolids-treated agricultural soils. Two application rates of biosolids (0, 5%, w/w) and four treatment levels (0, 1, 5, and 10 g/kg) of nZVI were examined, either separately or interactively. The results of this study showed significant differences in Ni+2 sorption capacity between different nZVI treatments. The initial Ni+2 concentration in biosolids-amended soil significantly affected Ni sorption in the soil treated with nZVI. The “H-shape” of sorption isotherm in nZVI-treated soil reflects strong interaction between the Ni concentration and the nZVI treatment, while the C-shape of sorption isotherm in biosolids-amended soil without the nZVI treatment indicates intermediate affinity for Ni+2 sorption. Nickel retention in soil was increased with the increase of nZVI levels. The removal efficiency of Ni+2 by nZVI from solution was increased with the increase of pH from 5 to 11 and reached a maximum of 99.56% at pH 11 and nZVI treatment of 10 g/kg. The Ni+2 desorption rate decreased from 92 to 7, 4, and 1% with increasing nZVI treatment levels from 0 to 1, 5, and 10 g/kg, respectively, with a soil Ni+2 concentration of 50 mg/L. The maximum adsorption capacity (𝑞max) of 10 g/kg nZVI-treated soil was 333.3 mg/g, which was much higher than those from the other treatments of 0 (5 mg/g), 1 (25 mg/g), and 5 g/kg (125 mg/g). The underlying mechanism for Ni+2 immobilization using nZVI in an aquatic environment is controlled by a sorption process, reduction of metal ion to zero-valent metal, as well as (co)precipitation. Moreover, increasing the nZVI treatment level in biosolids-amended soil significantly decreased bioavailable Ni+2 concentrations in the soil.  相似文献   
9.
10.
Clinical Oral Investigations - There is significant evidence that articaine and lidocaine buccal injections alone are sufficient for painless extraction of maxillary teeth. The aim of this study...  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