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   23746篇
  免费   1064篇
  国内免费   159篇
耳鼻咽喉   250篇
儿科学   657篇
妇产科学   455篇
基础医学   2843篇
口腔科学   726篇
临床医学   1714篇
内科学   6194篇
皮肤病学   316篇
神经病学   2157篇
特种医学   957篇
外科学   3867篇
综合类   87篇
一般理论   10篇
预防医学   1199篇
眼科学   271篇
药学   1357篇
中国医学   57篇
肿瘤学   1852篇
  2024年   19篇
  2023年   200篇
  2022年   435篇
  2021年   820篇
  2020年   443篇
  2019年   646篇
  2018年   858篇
  2017年   557篇
  2016年   627篇
  2015年   738篇
  2014年   981篇
  2013年   1178篇
  2012年   1944篇
  2011年   1866篇
  2010年   1133篇
  2009年   968篇
  2008年   1588篇
  2007年   1550篇
  2006年   1497篇
  2005年   1393篇
  2004年   1211篇
  2003年   1101篇
  2002年   1087篇
  2001年   131篇
  2000年   90篇
  1999年   143篇
  1998年   178篇
  1997年   149篇
  1996年   141篇
  1995年   143篇
  1994年   111篇
  1993年   107篇
  1992年   63篇
  1991年   50篇
  1990年   76篇
  1989年   54篇
  1988年   56篇
  1987年   33篇
  1986年   57篇
  1985年   37篇
  1984年   54篇
  1983年   46篇
  1982年   56篇
  1981年   40篇
  1980年   45篇
  1979年   27篇
  1978年   34篇
  1977年   22篇
  1973年   23篇
  1972年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
ObjectivesUterine adenosquamous carcinoma (ASC) is an uncommon, yet, one of the most aggressive cervical cancer subtype. The successful treatment of some tumors, such as gastrointestinal stromal tumors (GISTs), by anti-KIT inhibitors fosters the study of this receptor tyrosine kinase in other malignancies. In the present study, we intended to molecularly characterize KIT in ASC.MethodsIn a series of 30 cases, we studied KIT (CD117), KIT phosphorylated / activated form, as well as KIT ligand, stem cell factor (SCF), by immunohistochemistry. We further screened for KIT hotspot mutations (exon 9, 11, 13 and 17) by PCR-SSCP and for KIT gene amplification by Quantitative real-time PCR in CD117 positive cases.ResultsWe observed CD117 expression in ~ 13% of cases, with ~ 7% co-expressing SCF, which resulted in KIT phosphorylation/activation. No KIT activating mutations or gene amplification were found, despite the presence of 4q aneuploidy in one case.ConclusionsThis is the first study assessing KIT activation and molecular alterations in a large series of rare ASC. Our findings showed the absence of KIT molecular alterations and suggested the presence of KIT activation in a small proportion of cases through KIT/SCF co-expression.  相似文献   
104.

Objective

We aimed to study the cross-sectional area of levator ani muscle and the doppler velocimetric parameters of vessels its in premenopausal and postmenopausal women.

Study design

Sixty-four patients, divided into 3 groups, were assessed: group I (20 women—average age 28 years) premenopausal and nulliparous (control); group II (24 women—average age 38 years, vaginal delivery 1–4) premenopausal with vaginal deliveries; group III (20 women—average age 55 years, parity 0–4) postmenopausal without hormonal therapy. Doppler velocimetry of levator ani muscle vessels through resistance and pulsatility indices was used and the means of the groups compared by adjusting the weighed variance model with multiple comparisons, according to Tukey's method. Similarly, we measured the cross-sectional area of the muscle using ultrasonography.

Results

There was a significant increase in resistance and pulsatility indices in postmenopausal patients as compared to the other two groups. We also observed a significant decrease in the cross-sectional area of the muscle of postmenopausal patients when compared to those in premenopausal.

Conclusion

The obtained results allow us to conclude that levator ani muscle vascularization significantly decreases after menopause (age and/or hipoestrogenism) and that it can be assumed that vaginal delivery does not promote long-term alterations in levator ani muscle vascularization. We also observed a significant decrease in the cross-sectional area of the muscle in postmenopausal women when compared to those in premenopausal.  相似文献   
105.
Fertility preservation in young girls affected by malignancies has got growing relevance in the last decade due to the improved survival chance of these patients after oncostatic treatments. Most studies have focused on preserving ovarian follicles and avoiding premature ovarian failure, whereas only a few have evaluated the effects exerted by radiotherapy and chemotherapy on the uterus. It is self-evident that fertility preservation after oncostatic therapies must include the maintenance of a functional uterus, and a certain degree of uterine damage must be considered when estimating reproductive prognosis in previously treated, childhood cancer survivors. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader should be able to recall the growing number of children who survive oncostatic treatments, explain the possible effects on future reproductive endeavors, and summarize the possible ways to preserve fertility.  相似文献   
106.
107.
108.
109.
A macroscopic lithological study and physical (hardness, size, weight) investigations, coupled with laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) chemical analyses of three egg- and one pear-shaped polished black stones, exposed in the library of the child home of the famous poet Giacomo Leopardi, at Recanati (Italy), were carried out. They are characterized by different sizes: two with the same weight of 16.9 kg and the two smaller ones of 5.6 kg each, corresponding to multiples of standard roman weights (drachma and scrupulum). These features and the presence of some grooves on the rock artefacts, probably for grappling hooks, suggest an original use as counterweight for the four black stones herein classified as amphibole-bearing serpentinites whose lithologies are far away from Recanati (probably coming from geological outcrops in Tuscany). The four serpentinite stones closely match with the so-called Lapis Aequipondus used in antiquity by the Romans as counterweights. Due to the presence of lead rings or iron hooks in these stones, Lapis Aequipondus were also used for martyrdoms during the persecution of Christians in the Roman period, attached to the necks of martyrs that were then thrown in the wells or attached to the ankles of hanging bodies. This is the reason why these stones are also known as Lapis Martyrum, venerated with the relative martyrs, in several churches of Rome. The four black stones investigated probably arrived at Recanati from Rome after the middle of the 19th century. In the past, Christians also called Lapis Martyrum the “devil’s stones” (Lapis Diaboli). This could also be the reason for the popular belief that black stones cannot be touched by people, except those of the Leopardi dynasty. This work contributes to the cultural heritage of Leopardi’s child home, as the four black stones had never been investigated.  相似文献   
110.
Carinal re-resection for tumour recurrence is rarely performed due to increased difficulty in airway reconstruction. We reported a successful case of carinal resection and reconstruction for recurrent chondrosarcoma after previous distal tracheal resection. Due to the technical complexity of the reconstruction and the poor respiratory reserve of the patient, the veno-venous extracorporeal membrane oxygenation support was used.  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