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   895篇
  免费   60篇
  2021年   5篇
  2019年   6篇
  2018年   6篇
  2017年   6篇
  2016年   6篇
  2015年   23篇
  2014年   22篇
  2013年   68篇
  2012年   42篇
  2011年   37篇
  2010年   35篇
  2009年   28篇
  2008年   32篇
  2007年   41篇
  2006年   26篇
  2005年   25篇
  2004年   32篇
  2003年   45篇
  2002年   31篇
  2001年   36篇
  2000年   28篇
  1999年   22篇
  1998年   8篇
  1997年   6篇
  1995年   8篇
  1994年   9篇
  1993年   19篇
  1992年   33篇
  1991年   17篇
  1990年   27篇
  1989年   19篇
  1988年   17篇
  1987年   18篇
  1986年   21篇
  1985年   18篇
  1984年   15篇
  1983年   10篇
  1982年   17篇
  1981年   4篇
  1980年   5篇
  1979年   11篇
  1978年   6篇
  1977年   6篇
  1976年   11篇
  1975年   6篇
  1974年   4篇
  1971年   7篇
  1969年   4篇
  1967年   3篇
  1965年   3篇
排序方式: 共有955条查询结果,搜索用时 812 毫秒
921.
The purpose of this study is to examine the basic data useful for more comfortable folk clothes of Korean women, with respect to their thermal insulation effect. The result of this study is summarized as follows, by comparing the calculated thermal insulation effect of Korean women's folk clothes with that of the western style clothes. 1. The thermal insulation effect of the Korean women's folk clothes showed that summer clothes accounted for 0.67-0.93 Clo, while spring and autumn clothes showed 1.09-1.20 Clo. 2. Air layer had more effect on the thermal insulation of the Korean women's folk clothes than one of their material properties. 3. The thermal insulation of the Korean women's folk clothes features higher effect in the lower part of the body as compared with one the western style clothes, which act as an important factor in the thermal insulation.  相似文献   
922.

Dutch researchers were among the first to perform clinical studies in bare metal coronary stents, the use of which was initially limited by a high incidence of in-stent restenosis. This problem was greatly solved by the introduction of drug-eluting stents (DES). Nevertheless, enthusiasm about first-generation DES was subdued by discussions about a higher risk of very-late stent thrombosis and mortality, which stimulated the development, refinement, and rapid adoption of new DES with more biocompatible durable polymer coatings, biodegradable polymer coatings, or no coating at all. In terms of clinical DES research, the 2010s were characterised by numerous large-scale randomised trials in all-comers and patients with minimal exclusion criteria. Bioresorbable scaffolds (BRS) were developed and investigated. The Igaki-Tamai scaffold without drug elution was clinically tested in the Netherlands in 1999, followed by an everolimus-eluting BRS (Absorb) which showed favourable imaging and clinical results. Afterwards, multiple clinical trials comparing Absorb and its metallic counterpart were performed, revealing an increased rate of scaffold thrombosis during follow-up. Based on these studies, the commercialisation of the device was subsequently halted. Novel technologies are being developed to overcome shortcomings of first-generation BRS. In this narrative review, we look back on numerous devices and on the DES and BRS trials reported by Dutch researchers.

  相似文献   
923.
924.
We transfected rat pheochromocytoma (PC12) cells with a cDNA encoding chicken integrin beta 1 subunit. The chicken integrin beta 1 subunit produced in stable transfectants associated with two major alpha subunits of rat integrins to form interspecific chimeric receptors. These receptors mediated cell spreading and initial neurite outgrowth on laminin as did corresponding endogenous integrins, although they were slightly less effective in inducing cell adhesion to laminin. These results indicate that chicken integrin beta 1 may functionally substitute for beta 1 subunit of rat integrins in PC12 cells. Apparently, the structure of the integrin beta 1 subunit is highly conserved in the evolution of these species.  相似文献   
925.
The intergenic spacer (IGS) region, which is located between the 3′ end of 26S ribosomal DNA (rDNA) and the 5′ end of 5S rDNA, of sixArmillaria species from Hokkaido was investigated using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Restriction with onlyAlu I could distinguishA. mellea subsp.nipponica from the other species. WithAlu I andDde I,A. ostoyae andA. gallica could be distinguished from the other species. Digestion withAlu I resulted in two patterns (types A and B) ofA. singula and three patterns (types A, B, and C) ofA. jezoensis. One pattern (type B) of the former species and two patterns (types B and C) of the latter species were each different from those of the other species.Armillaria sinapina gave only oneAlu I digestion pattern, which was identical to that ofA. jezoensis (type A) andA. singula (type A). However, by digestion withDde I,A. singula (type A) could be distinguished fromA. jezoensis (type A) andA. sinapina.  相似文献   
926.
Sleep and Biological Rhythms - Narcolepsy is a chronic sleep disorder, and dysfunction in hypocretinergic neurotransmission has been shown to underlie the pathophysiology of this disorder....  相似文献   
927.
928.
Calcium-activated neutral proteases (CANPs) with high sensitivity (microCANP) and low sensitivity (mCANP) to calcium ions were purified individually from rabbit skeletal muscle and rabbit lung and compared as to their electrophoretic properties, calcium requirements and peptide mapping of fragments produced by S. aureus V8 protease digestion of separated subunits. All of the results suggested that there is no difference between the microCANPs as well as between the mCANPs obtained from the two tissues, with respect to the chemical and enzymatic properties. However, the contents of CANPs in these tissues were different.  相似文献   
929.
Neural lobe function in male rats of the Wistar/Tw strain was studied at 3, 7 and 16-18 months of age. A significant rise in the serum arginine vasopressin (AVP) level was noted in 16-18-month-old rats showing polydipsia and polyuria. The content and concentration of AVP in the neural lobe of aged rats were significantly less than those of younger animals (3 and 7 months). These results point out an enhancement of AVP release from the neural lobe of aged rats. The reduction in urinary volume in aged rats subjected to 24 hours of water deprivation was less than those in younger animals. No increase in urinary sodium, potassium and chloride concentrations was observed in aged rats, and the decrease in electrolyte excretion from urine during the dehydration period was less in aged rats than younger ones. These results suggest that the antidiuretic response to osmotic stimuli was reduced in aged rats. The administration of AVP to aged rats resulted in a significant decrease in water intake and urinary volume, but AVP administration did not induce any change in the electrolyte balance. Therefore, it is concluded that the main cause of the development of polydipsia and polyuria is the decline in renal function but not in neurosecretory activity, although exogenous AVP can effectively reduce water intake and urinary output in aged rats.  相似文献   
930.
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