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   4876篇
  免费   204篇
  国内免费   30篇
耳鼻咽喉   47篇
儿科学   66篇
妇产科学   27篇
基础医学   558篇
口腔科学   84篇
临床医学   278篇
内科学   1243篇
皮肤病学   62篇
神经病学   262篇
特种医学   208篇
外科学   970篇
综合类   60篇
预防医学   180篇
眼科学   126篇
药学   247篇
中国医学   33篇
肿瘤学   659篇
  2024年   4篇
  2023年   35篇
  2022年   99篇
  2021年   168篇
  2020年   71篇
  2019年   81篇
  2018年   105篇
  2017年   82篇
  2016年   124篇
  2015年   118篇
  2014年   164篇
  2013年   219篇
  2012年   328篇
  2011年   341篇
  2010年   205篇
  2009年   182篇
  2008年   292篇
  2007年   340篇
  2006年   291篇
  2005年   289篇
  2004年   320篇
  2003年   308篇
  2002年   287篇
  2001年   50篇
  2000年   44篇
  1999年   46篇
  1998年   72篇
  1997年   70篇
  1996年   57篇
  1995年   40篇
  1994年   39篇
  1993年   32篇
  1992年   26篇
  1991年   20篇
  1990年   15篇
  1989年   11篇
  1988年   11篇
  1987年   20篇
  1986年   8篇
  1985年   17篇
  1984年   11篇
  1983年   4篇
  1982年   12篇
  1981年   9篇
  1980年   7篇
  1979年   6篇
  1978年   5篇
  1977年   7篇
  1976年   5篇
  1957年   2篇
排序方式: 共有5110条查询结果,搜索用时 15 毫秒
981.
982.
983.
Lung cancer is the leading cause of cancer-related death worldwide. Small-cell lung cancer (SCLC) accounts for approximately 15% of all lung cancers. It is characterized by rapid tumor growth and early metastasis to multiple organs. Response to initial chemotherapy is generally good; however, the majority of patients develop recurrence and the prognosis of such patients is reportedly 2–4 months. Evolution of the treatment for SCLC has stagnated, and cisplatin + etoposide has been the standard chemotherapy for decades. Meanwhile, the combination of cisplatin + irinotecan has demonstrated equivalent efficacy to cisplatin + etoposide. Recently, maintenance chemotherapy has been extensively investigated in non-small-cell lung cancer (NSCLC), and is currently recommended as a standard treatment in clinical guidelines. On the contrary, a maintenance strategy has not been established for SCLC. Here, we describe an SCLC patient who received maintenance chemotherapy with irinotecan for more than 2 years after induction chemotherapy with cisplatin + irinotecan, and survived long term with no recurrence.Key Words: Small-cell lung cancer, Irinotecan, Maintenance, Long survivor, Extensive disease  相似文献   
984.
985.
A carbon paste of SiO2/Nb2O5 material was used as the electrode in the development of a dissolved dioxygen sensor in 1.0 mol l?1 KCl solution at pH 6.2. The material was prepared by the sol–gel method. In the investigation of its electrochemical properties, linear and cyclic voltammetric and chronoamperometric techniques were employed. Dioxygen reduction, which was diffusion controlled, occurred at ?280 mV vs. SCE by a two electron mechanism, producing peroxide. A linear response between the cathodic peak current intensity and the dissolved O2 concentration was obtained for the region between 1.0 and 13.6 mg l?1. The stability proved to be very good over successive voltammetric cycles. The electrode response time was about 5 s. The electron transfer reactions were explained as being to an n-type semiconductor of niobia dispersed in the silica surface.  相似文献   
986.
We investigated the frequency, site, amount, and direction of facial asymmetry in human adults with mandibular prognathism and examined if these characteristics were associated postnatally with cardinal clinical signs that may indicate a predisposition to facial asymmetry. Two hundred twenty young Japanese adults (69 men and 151 women) who exhibited skeletal Class III malocclusions were selected. The sample was divided into a Postnatal Factor Group and a Nonpostnatal Factor Group. The former group included those who had: (1) received orthodontic treatment using a chin cap; (2) exhibited clinical symptoms of temporomandibular joint (TMJ) disorder; (3) reported a history of maxillofacial trauma; or (4) radiographic abnormality of the condyles. Subjects with a deviation of more than 2 mm from the facial midline associated with any of the 4 landmarks (ANS, U1, L1 and Me) were classified as asymmetric and the asymmetry was measured on a postero-anterior (P-A) cephalogram. Radiographic facial asymmetry was found frequently (70%-85%, for Menton), and most obviously in the lower jaw (P < .05). Lateral displacement toward the left side of the face occurred more often than right-sided deviation (P < .001, for Menton). However, the Postnatal Factor Group showed a higher proportion of subjects with lateral deviation toward the right side (P = .0031) and a greater amount (P < .0001) of chin deviation. This was due to the fact that the subjects having TMJ problems as a postnatal factor showed no directional uniqueness in jaw deviation and exhibited a longer distance of deviation.  相似文献   
987.
The purpose of this study was to measure the tensile and shear bond strength of resin-reinforced glass ionomer cement (RGIC) to glazed porcelain, to evaluate the durability of RGIC by thermal cycling, and to examine the RGIC remaining on the surface of the porcelain after the bond strength test to evaluate bonding conditions. Three adhesives were used in this study: Concise (CO) as a chemically cured composite resin, Fuji ORTHO (FO) as a chemically cured RGIC, and Fuji ORTHO LC (FOLC) as a light-cured RGIC. Tensile and shear bond strengths were measured 24 hours after bonding orthodontic brackets and also after thermal cycling. Tensile bond strength after 24 hours was 6.6 +/- 3.2 MPa in CO, 7.3 +/- 1.4 MPa in FO, and 8.6 +/- 1.9 MPa in FOLC, and the strength significantly decreased after the thermal cycling test. Shear bond strength after 24 hours was 32.5 +/- 8.9 MPa in CO, 23.3 +/- 6.8 MPa in FO, and 24.7 +/- 6.5 MPa in FOLC, and in contrast to tensile bond strength, no decreases in the strength were detected after the thermal cycling test. CO showed significantly higher shear bond strength than did FO and FOLC. When using the shear bond strength test and CO, destruction of porcelain surfaces frequently occurred after 24 hours and was observed in every specimen after the thermal cycling. RGIC was found to be an advantageous alternative to resin adhesive for bracket bonding to porcelain and to enamel.  相似文献   
988.
A mini-implant for orthodontic anchorage in a deep overbite case   总被引:4,自引:0,他引:4  
This article describes the orthodontic treatment of a 19-year-old female patient with anterior crowding. There was a moderate arch length discrepancy in the lower dental arch, a significant deep overbite, and a "gummy smile." We inserted an orthodontic mini-implant as anchorage for the intrusion of the upper incisor segment, followed by alignment of the upper and lower dental arches with an edgewise appliance without tooth extraction. The overbite was corrected from +7.2 mm to +1.7 mm by upper incisor intrusion, and the gummy smile was improved. Good occlusion and facial esthetics were achieved, and these results have been maintained for two years after completion of the active treatment.  相似文献   
989.
目的:分析研究革叶山姜叶挥发油的主要成分及其抗肿瘤活性。方法:采取水蒸气蒸馏法从革叶山姜叶中提取挥发油,利用GC-MS对其化学成分进行分析。采用MTT法检测革叶山姜叶挥发油对细胞Hela、A549的增殖抑制作用。结果 :共分离出39个峰,鉴定出31个化学成分,占挥发油总量的94.81%。其主要成分为芳樟醇(34.91%)、橙花叔醇(18.23%)和桉叶油醇(14.48%)。抑制肿瘤细胞增殖的活性结果表明革叶山姜叶挥发油对2种肿瘤细胞株均有一定的抑制活性,其中对人肺腺癌细胞A549的抑制活性相对较好,其IC50值为14.01μg·m L-1。结论:该实验为革叶山姜的进一步开发研究提供可靠的科学依据。  相似文献   
990.
OBJECTIVE: In this report, the orthodontic treatment combined with rigid external distraction osteogenesis in a 5.5-year-old girl with midfacial hypoplasia and oligodontia is described. PATIENT: The child presented with a reduced maxilla, protruding lower lip, skeletal Class III jaw relationship with a low mandibular plane angle, a short and flattened nose, anterior crossbite, and aplasia of 16 permanent teeth. The patient was treated with rigid external maxillary distraction osteogenesis, maxillary protraction headgear, and Class III elastics. Following treatment, the maxilla was displaced in a forward direction with new bone formation at the tuberosities and the mandible rotated backward in relation to the anterior cranial base. The anterior crossbite was corrected, and the skeletal jaw relationship changed from a Class III to a Class I skeletal pattern. The soft tissue facial profile showed that the nasal projection had been increased, the nasolabial angle increased, and the lower lip protrusion was reduced. Postoperative treatment results were acceptable. CONCLUSION: This report documents that early maxillary advancement with rigid external osteogenesis offers a promising treatment alternative for a very young patient with maxillary hypoplasia and oligodontia.  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