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   269篇
  免费   21篇
  290篇
  2022年   4篇
  2021年   3篇
  2020年   3篇
  2019年   4篇
  2018年   7篇
  2017年   5篇
  2016年   6篇
  2015年   10篇
  2014年   9篇
  2013年   9篇
  2012年   18篇
  2011年   14篇
  2010年   13篇
  2009年   20篇
  2008年   13篇
  2007年   14篇
  2006年   14篇
  2005年   14篇
  2004年   7篇
  2003年   10篇
  2002年   7篇
  2001年   9篇
  2000年   4篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1994年   2篇
  1989年   6篇
  1988年   2篇
  1986年   2篇
  1979年   2篇
  1976年   4篇
  1975年   2篇
  1974年   2篇
  1972年   2篇
  1970年   2篇
  1968年   3篇
  1967年   2篇
  1964年   2篇
  1960年   2篇
  1955年   3篇
  1954年   1篇
  1953年   1篇
  1952年   1篇
  1951年   3篇
  1945年   1篇
  1944年   1篇
  1943年   1篇
  1917年   1篇
  1904年   1篇
排序方式: 共有290条查询结果,搜索用时 0 毫秒
281.
The distribution of GYIRFamide immunoreactivity in the nervous system ofMacrostomum hystricinum marinum has been demonstrated by an indirect fluorescence technique in conjunction with confocal scanning laser microscopy (CSLM). Immunostaining was extensive in both the central (CNS) and peripheral (PNS) nervous systems, revealing detailed information on the microanatomy of the peptidergic nervous system of this free-living plathelminth. In the CNS, immunoreactive nerve cell bodies and nerve fibres occurred in the brain and along two pairs of longitudinal nerve cords: the main nerve cords and the ventral nerve cords. In the PNS, immunostaining was prevalent in nerve cells and fibres innervating the pharynx and the gut. The employed antibody is directed against a recently characterised FMRF-amide-related peptide (FaRP), GYIRFamide, isolated from two species of the Tricladida,Dugesia tigrina andBdelloura candida. Phylogenetically, GYIRFamide represents the most ancient neuropeptide thus far identified within the Bilateria  相似文献   
282.
Developmental changes in energy metabolism of primary hippocampal cell cultures from newborn rats were investigated during the first 3 weeks. These changes were measured by intensity of and number of cells exhibiting NAD(P)H fluorescence in response to NMDA-induced activation of neuronal activity. We observed gradual changes of stimulation-evoked NAD(P)H signaling over the first 3 weeks, such that at day 7 and 16, this stimulation is minimal, while at 5 and 12 days, it is maximal. These results describe a biphasic pattern that was similar to earlier findings from experiments investigating developmental changes in population spike amplitudes or glutamate release in young rats. Inhibition of mitochondrial respiration by KCN revealed that the NMDA-evoked stimulation of energy metabolism is mainly due to increased glycolytic activity.  相似文献   
283.
A case of primary small cell undifferentiated carcinoma (SCUC) of the parotid gland, diagnosed initially by fine needle aspiration (FNA) cytology and confirmed by histology, immunohistochemistry and transmission electron microscopy (TEM), is presented. The FNA cytologic features that enabled an accurate diagnosis of this rare salivary gland tumor included nuclear granularity and markedly angular nuclear molding of numerous small cells that were usually present as large syncytia in an inflammatory background. Numerous mitotic figures were also present in this vascular lesion. These features were also evident in the surgical specimens. Immunohistochemistry demonstrated neuron-specific enolase positivity while TEM demonstrated intracytoplasmic neurosecretory granules in this case, indicating a neuroendocrine derivation for this neoplasm instead of the more usual origin of salivary gland SCUCs in ductal epithelial or myoepithelial tissue.  相似文献   
284.
285.
Mucinous cystadenocarcinoma of the pancreas is among the few potentially curable malignancies of this organ; recognition of the differences between this and other pancreatic tumors is thus of paramount importance. A second example of mucinous cystadenocarcinoma of the pancreas diagnosed by fine needle aspiration, performed under ultrasonographic guidance, is presented, emphasizing both the radiographic distinction from other cystic lesions plus cytologic features not previously stressed. In essence, the cytodiagnosis relies less on cell morphology, which is characteristically bland and relatively monomorphic, than on the presence of extracellular mucin, which must be distinguished from amorphous background material and necrotic debris. The possibility of diagnosing benign mucinous and serous cystadenomas by imaging and cytology is addressed.  相似文献   
286.
D B?ttcher  K Hasler  A H Sutor  D Mair 《Blut》1976,33(1):33-40
A family is described in which 5 out of 8 children had a marked bleeding disorder. The children showed prolonged bleeding times, abnormal platelet retention upon passage of blood through a glass bead column, the Willebrand factor activity as measured by ristocetin in a washed platelet system was low. Factor VIII/von Willebrand factor protein levels were normal even so the factor VIII-procoagulant activity. Even the parents and one child without any bleeding tendency and normal bleeding times had a reduced Willebrand factor activity. In all these patients evidence of an abnormal protein was observed on crossed antigen-antibody electrophoresis indicating a qualitative defect of the factor VIII/von Willebrand factor protein.  相似文献   
287.
288.
Abstract

Purpose: The Fourth Universal Definition of Myocardial Infarction (MI) has highlighted the different pathophysiological mechanisms that may lead to ischaemic and non-ischaemic myocardial injury and has emphasised that the diagnosis of myocardial infarction requires the presence of acute myocardial ischaemia in the setting of acute myocardial injury. This case based review intends to illustrate basic principles on how to apply this new, revised definition in clinical practice.

Methods and Results: The distinction between different types of MIs (type 1 or type 2) and the delineation of MI from acute non-ischaemic myocardial injury may be challenging in individual patients, which is illustrated by presenting and discussing real-life routine cases.

Conclusions: Type 1?MI is a consequence of coronary plaque rupture or erosion with intracoronary thrombus formation that is usually apparent on coronary angiography. Plausible triggering mechanisms causing myocardial oxygen supply/demand mismatch must be identified for the diagnosis of type 2?MI and its treatment should focus initially on management of the underlying disease attributable to acute myocardial ischaemia.  相似文献   
289.
Livingand recently preserved postlarvae of Penaeus vannameiBoone, P. stylirostris Stimpson, P. californiensis (Holmes) and P. brevirostris Kingsley may be separated into species on chromatophore patterns and rostral lengths. These and other characters are illustrated and tabulated, and their usefulness and reliability are discussed.  相似文献   
290.
S Mair 《Acta cytologica》1989,33(6):903-906
Fine needle aspiration (FNA) of bilaterally enlarged submandibular salivary glands yielded both Curschmann's spirals and actinomycetes filaments in the FNA smears. Histologic study of specimens from the bilateral submandibulectomy confirmed the actinomycosis but failed to demonstrate the presence of spirals. The presence of Curschmann's spirals in FNA material is a finding not previously described in the English literature. Actinomycosis, although well documented in exfoliative cytology, has been rarely reported in fine needle aspirates. This unique case afforded the opportunity of illustrating the characteristic features of Curschmann's spirals and actinomycetes colonies, as well as reviewing the etiology and pathogenesis of Curschmann's spirals, in FNA material.  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