全文获取类型
收费全文 | 170篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
儿科学 | 4篇 |
基础医学 | 56篇 |
口腔科学 | 2篇 |
临床医学 | 4篇 |
内科学 | 20篇 |
皮肤病学 | 1篇 |
神经病学 | 8篇 |
外科学 | 67篇 |
预防医学 | 1篇 |
药学 | 7篇 |
肿瘤学 | 3篇 |
出版年
2022年 | 2篇 |
2021年 | 11篇 |
2019年 | 2篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
2.
The cardiac neural crest is located in a transitional area on the neuraxis between trunk and cephalic regions and gives rise to both the dorsolateral and ventrolateral crest cell populations. Around stage 18 of chick development, a mass of E/C8+ cells surrounds the postotic pharyngeal arches and forms a crescent-shaped arch, termed the circumpharyngeal ridge. Using immunohistochemistry and quail-chick chimeras, it was determined that the E/C8+ cell mass located in the circumpharyngeal ridge derives from the dorsolateral component of the cardiac neural crest. The ventrolateral cell population of the cardiac crest is located more medially and shows long-persistent HNK-1 immunoreactivity dorsolateral to the foregut. The crest cells that populate the gut arise from the caudal portion of the circumpharyngeal crest and are always located caudal to the caudalmost pharyngeal ectomesenchyme. Circumpharyngeal crest cells continuously populate the pharyngeal arch ectomesenchyme and enteric nervous system on the lateral side of the foregut wall, as well as the hypoglossal pathway which develops within the ventral portion of the circumpharyngeal ridge. E/C8 and HNK-1 immunoreactivity are associated with the cells migrating via the dorsolateral (circumpharyngeal) and ventrolateral pathways, respectively, with one exception: there is a population of putative crest cells along the proximal course of the vagal intestinal branch that shows both immunoreactivities around stage 20. Dil labeling of the cells in the circumpharyngeal ridge suggests that the cells are contributed from the circumpharyngeal ridge to this population. Thus, the distribution of the circumpharyngeal crest cells and their derivatives coincides with the peripheral branch distribution of the cranial nerves IX, X, and XII, whose development is selectively affected in the absence of the cardiac neural crest, the source of the circumpharyngeal crest.© Willey-Liss, Inc. 相似文献
3.
Hiroshi Nagashima Katsuhisa Uchida Keiko Yamamoto Shigehiro Kuraku Ryo Usuda Shigeru Kuratani 《Developmental dynamics》2005,232(1):149-161
Turtles have a body plan unique among vertebrates in that their ribs have shifted topographically to a superficial layer of the body and the trunk muscles are greatly reduced. Identifying the developmental factors that cause this pattern would further our understanding of the evolutionary origin of the turtles. As the first step in addressing this question, we replaced newly developed epithelial somites of the chicken at the thoracic level with those of the Chinese soft-shelled turtle Pelodiscus sinensis (P. sinensis somites into a chicken host) and observed the developmental patterning of the grafted somites in the chimera. The P. sinensis somites differentiated normally in the chicken embryonic environment into sclerotomes and dermomyotomes, and the myotomes differentiated further into the epaxial and hypaxial muscles with histological morphology similar to that of normal P. sinensis embryos and not to that of the chicken. Epaxial dermis also arose from the graft. Skeletal components, however, did not differentiate from the P. sinensis sclerotome, except for small fragments of cartilage associated with the host centrum and neural arches. We conclude that chicken and P. sinensis share the developmental programs necessary for the early differentiation of somites and that turtle-specific traits in muscle patterning arise mainly through a cell-autonomous developmental process in the somites per se. However, the mechanism for turtle-specific cartilage patterning, including that of the ribs, is not supported by the chicken embryonic environment. 相似文献
4.
Yoko Suda Isao Matsuo Shigeru Kuratani & Shinichi Aizawa 《Genes to cells : devoted to molecular & cellular mechanisms》1996,1(11):1031-1044
Background: We previously reported that the homozygous mutation of Otx2 gene, a mouse cognate of the Drosophila head gap gene orthodenticle , causes failure in the development of the rostral head anterior to rhombomere 3, which may correspond to earlier Otx2 expression in cells destined for the anterior mesoendoderm. At the same time, the Otx2 heterozygous mutation displayed a phenotype characterized as otocephaly, probably related to expression in the anterior neuroectoderm at the subsequent pharyngula stage. Defects were characteristic in the most anterior and posterior regions of Otx2 expression where Otx1 , another mouse cognate of orthodenticle , is not or weakly expressed. They were not found in the region where Otx1 is expressed.
Results: In the present work, Otx1 null mutant mice were generated by gene targeting in embryonic stem cells. No defects were apparent in the regionalization of the early embryonic rostral brain. The newborn brain defects were subtle and most likely related to later Otx1 -unique expression. Otx1 and Otx2 double heterozygous mutant brains, however, exhibited marked defects throughout the fore- and midbrains, where defects were not apparent with a single mutation alone.
Conclusions: Otx1 and Otx2 play synergistic roles in the development of the forebrain and midbrain where both genes are expressed. 相似文献
Results: In the present work, Otx1 null mutant mice were generated by gene targeting in embryonic stem cells. No defects were apparent in the regionalization of the early embryonic rostral brain. The newborn brain defects were subtle and most likely related to later Otx1 -unique expression. Otx1 and Otx2 double heterozygous mutant brains, however, exhibited marked defects throughout the fore- and midbrains, where defects were not apparent with a single mutation alone.
Conclusions: Otx1 and Otx2 play synergistic roles in the development of the forebrain and midbrain where both genes are expressed. 相似文献
5.
6.
Background We developed and evaluated the clinical usefulness of a scoring system that subclassified type Vi pit patterns.
Methods We studied 119 colon cancer lesions (pTis, n = 26; pT1, n = 93) and 22 tubular adenoma lesions with severe atypia in which a type Vi pit pattern was visible under a stereomicroscope. Four type Vi pit pattern formation appearances (existing pits, marginal irregularities of the gland duct, narrowing of the gland duct
lumen, and unclear outline of the gland duct) were defined, and the relationship between each appearance and the invasive
depth of the cancer was evaluated.
Results When the four type Vi pit pattern appearances were considered in a logistic regression analysis, the odds of a more invasive submucosal cancer
were significantly increased by the appearance of marginal irregularities, a narrowed lumen, and an unclear outline. In the
logistic regression analysis results, when 0.63 was used as the cutoff score for prediction of a more invasive submucosal
cancer, 80 cases in the less invasive group were classified correctly (specificity, 1.0), whereas 53 (86.9%) of the 61 cases
in the more invasive group were classified correctly (sensitivity, 0.869).
Conclusions It is important first to understand the usability and limitations of objective scoring of type V pit pattern findings and
then to apply this score to the determination of cancer depth in order to accurately identify lesions suitable for endoscopic
treatment. 相似文献
7.
The evolutionary origin of the diaphragm remains unclear, due to the lack of a comparable structure in other extant taxa. However, recent researches into the developmental mechanism of this structure have yielded new insights into its origin. Here we summarize current understanding regarding the development of the diaphragm, and present a possible scenario for the evolutionary acquisition of this uniquely mammalian structure. Recent developmental analyses indicate that the diaphragm and forelimb muscles are derived from a shared cell population during embryonic development. Therefore, the embryonic positions of forelimb muscle progenitors, which correspond to the position of the brachial plexus, likely played an important role in the evolution of the diaphragm. We surveyed the literature to reexamine the position of the brachial plexus among living amniotes and confirmed that the cervico‐thoracic transition in ribs reflects the brachial plexus position. Using this osteological correlate, we concluded that the anterior borders of the brachial plexuses in the stem synapsids were positioned at the level of the fourth spinal nerve, suggesting that the forelimb buds were laid in close proximity of the infrahyoid muscles. The topology of the phrenic and suprascapular nerves of mammals is similar to that of subscapular and supracoracoid nerves, respectively, of the other amniotes, suggesting that the diaphragm evolved from a muscle positioned medial to the pectoral girdle (cf. subscapular muscle). We hypothesize that the diaphragm was acquired in two steps: first, forelimb muscle cells were incorporated into tissues to form a primitive diaphragm in the stem synapsid grade, and second, the diaphragm in cynodonts became entrapped in the region controlled by pulmonary development. 相似文献
8.
Shigeru Kuratani Noritaka Adachi Naoyuki Wada Yasuhiro Oisi Fumiaki Sugahara 《Journal of anatomy》2013,222(1):41-55
The cephalic neural crest produces streams of migrating cells that populate pharyngeal arches and a more rostral, premandibular domain, to give rise to an extensive ectomesenchyme in the embryonic vertebrate head. The crest cells forming the trigeminal stream are the major source of the craniofacial skeleton; however, there is no clear distinction between the mandibular arch and the premandibular domain in this ectomesenchyme. The question regarding the evolution of the gnathostome jaw is, in part, a question about the differentiation of the mandibular arch, the rostralmost component of the pharynx, and in part a question about the developmental fate of the premandibular domain. We address the developmental definition of the mandibular arch in connection with the developmental origin of the trabeculae, paired cartilaginous elements generally believed to develop in the premandibular domain, and also of enigmatic cartilaginous elements called polar cartilages. Based on comparative embryology, we propose that the mandibular arch ectomesenchyme in gnathostomes can be defined as a Dlx1-positive domain, and that the polar cartilages, which develop from the Dlx1-negative premandibular ectomesenchyme, would represent merely posterior parts of the trabeculae. We also show, in the lamprey embryo, early migration of mandibular arch mesenchyme into the premandibular domain, and propose an updated version of the heterotopy theory on the origin of the jaw. 相似文献
9.
Masuda Hirotada Miyagawa Shigeru Sugiura Seiryo Washio Takumi Okada Jun-ichi Ueno Takayoshi Toda Koichi Kuratani Toru Hisada Toshiaki Sawa Yoshiki 《Journal of artificial organs》2021,24(3):351-357
Journal of Artificial Organs - Despite advancements in preoperative prediction of patient outcomes, determination of the most appropriate surgical treatments for patients with severely impaired... 相似文献
10.
Watanabe Takuji Ueno Takayoshi Tominaga Yuji Araki Kanta Kanaya Tomomitsu Taira Masaki Toda Koichi Kuratani Toru Sawa Yoshiki 《Journal of artificial organs》2021,24(2):258-260
Journal of Artificial Organs - A 45-year-old woman with repaired complex congenital heart disease, who underwent placement of Jarvik 2000, a ventricular assist device (VAD) for 4 years,... 相似文献