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   20760篇
  免费   1175篇
  国内免费   77篇
耳鼻咽喉   222篇
儿科学   556篇
妇产科学   379篇
基础医学   2559篇
口腔科学   742篇
临床医学   1640篇
内科学   4657篇
皮肤病学   590篇
神经病学   2175篇
特种医学   657篇
外国民族医学   3篇
外科学   3003篇
综合类   141篇
一般理论   4篇
预防医学   1361篇
眼科学   432篇
药学   1355篇
中国医学   84篇
肿瘤学   1452篇
  2023年   114篇
  2022年   203篇
  2021年   581篇
  2020年   311篇
  2019年   428篇
  2018年   518篇
  2017年   344篇
  2016年   417篇
  2015年   477篇
  2014年   671篇
  2013年   825篇
  2012年   1422篇
  2011年   1408篇
  2010年   806篇
  2009年   691篇
  2008年   1238篇
  2007年   1229篇
  2006年   1137篇
  2005年   1166篇
  2004年   1039篇
  2003年   932篇
  2002年   881篇
  2001年   521篇
  2000年   528篇
  1999年   438篇
  1998年   174篇
  1997年   144篇
  1996年   155篇
  1995年   130篇
  1994年   132篇
  1993年   108篇
  1992年   318篇
  1991年   255篇
  1990年   242篇
  1989年   208篇
  1988年   176篇
  1987年   161篇
  1986年   168篇
  1985年   157篇
  1984年   121篇
  1983年   88篇
  1982年   67篇
  1981年   65篇
  1980年   56篇
  1979年   102篇
  1978年   53篇
  1974年   52篇
  1973年   52篇
  1972年   70篇
  1971年   51篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Classical Kaposi sarcoma (KS) usually appears on lower extremities accompanied or preceded by local lymphedema. However, the development in areas of chronic lymphedema of the arms following mastectomy, mimicking a Stewart–Treves syndrome, has rarely been described. We report an 81‐year‐old woman who developed multiple, erythematous to purple tumors, located on areas of post mastectomy lymphedema. Histopathological examination evidenced several dermal nodules formed by spindle‐shaped cells that delimitated slit‐like vascular spaces with some red cell extravasation. Immunohistochemically, the human herpesvirus type 8 (HHV‐8) latent nuclear antigen‐1 was detected in the nuclei of most tumoral cells confirming the diagnosis of KS. Lymphedema could promote the development of certain tumors by altering immunocompetence. Although angiosarcoma (AS) is the most frequent neoplasia arising in the setting of chronic lymphedema, other tumors such as benign lymphangiomatous papules (BLAP) or KS can also develop in lymphedematous limbs. It is important to establish the difference between AS and KS because their prognosis and treatment are very different. Identification by immunohistochemistry of HHV‐8 is useful for the distinction between KS and AS or BLAP.  相似文献   
2.
3.
Journal of Digital Imaging - Vertebral Compression Fracture (VCF) occurs when the vertebral body partially collapses under the action of compressive forces. Non-traumatic VCFs can be secondary to...  相似文献   
4.
5.
6.
7.
IntroductionPeople with Down syndrome (DS) have high respiratory morbidity, evaluating their respiratory health with standardized, objective tests is desirable. Thus, the objective of this study was to evaluate the technical quality of Pulmonary Function Tests (PFTs) to determine which ones are most suitable for this population.MethodsParticipants included children, teenagers and adults with DS, 5 years of age or older (n = 302). The technical quality of the impulse oscillometry system (IOS), forced spirometry, lung-diffusing capacity for carbon monoxide (DLCO), and 6-min walk test (6MWT) were analyzed by age group. Capnography and pulse oximetry were included in the study. Technical quality was determined on the basis of current international PFTs standards.ResultsFifty-one percent of participants were males. A total of 184 participants (71%) who completed the IOS fulfilled the quality criteria, while 210 (70%) completed the 6MWT. Performance on forced spirometry and DLCO was poor. All pulse oximetries and 96% percent heart rates obtained had good quality, but exhaled carbon dioxide (PetCO2) and respiratory rate (RR) showed deficient repeatability.ConclusionsIOS appears to be the most reliable instrument for evaluating lung mechanics in individuals with DS.  相似文献   
8.
9.
10.
Placenta is an important source of leptin during pregnancy that contributes to the high plasma leptin levels in pregnant women. Leptin and its functional receptors are synthesized in trophoblast cells that, in turn, secrete gestational hormones supporting a paracrine or autocrine role for leptin in the endocrine activity of the placenta. In the present study we examined the effect of leptin on in vitro release of gestational hormones (human chorionic gonadotropin (hCG), human placental lactogen (hPL), progesterone, estrogens and testosterone) by human term placental cells in culture. Placentas at term were obtained immediately after delivery from mothers with uncomplicated pregnancies. Progesterone, hCG, hPL, estradiol, estrone, estriol and testosterone levels were measured by different assays in culture media of cells maintained in monolayer culture after incubation for 12, 24, 48 or 72 h with leptin or placebo. Incubation with leptin did not modify hCG, hPL, progesterone, estriol and estrone secretion for any of the doses and times assayed. However, leptin led to a dose-dependent decrease in estradiol release. This effect was observed when treatment with recombinant human leptin spanned from 12 to 72 h. At this time an increase in testosterone levels was observed in leptin-treated cells versus placebo. These results indicate that leptin can be considered a gestational hormone implied in the endocrine function of the placenta, with an important role in control of the production of steroid reproductive hormones in placental cells in vitro.  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