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   245篇
  免费   16篇
  2022年   3篇
  2021年   2篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   7篇
  2014年   12篇
  2013年   12篇
  2012年   18篇
  2011年   7篇
  2010年   15篇
  2009年   7篇
  2008年   15篇
  2007年   16篇
  2006年   17篇
  2005年   14篇
  2004年   9篇
  2003年   5篇
  2002年   6篇
  2001年   4篇
  2000年   5篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1995年   2篇
  1994年   4篇
  1993年   5篇
  1992年   3篇
  1991年   5篇
  1990年   10篇
  1989年   2篇
  1988年   2篇
  1987年   4篇
  1986年   1篇
  1983年   1篇
  1980年   5篇
  1979年   2篇
  1978年   2篇
  1977年   8篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1972年   3篇
  1971年   2篇
  1969年   2篇
  1966年   1篇
  1964年   2篇
排序方式: 共有261条查询结果,搜索用时 62 毫秒
251.
252.
253.
Blood pressure ambulatory monitoring has provided numerous and interesting informations on the clinical as well as investigational setting of arterial hypertension. The vast majority of data have been obtained registering blood pressure during the normal daily activities of the patients and surprisingly few studies have been undertaken to evaluate blood pressure behaviour in inpatients. We observed the 24 hours pattern of blood pressure in hypertensive and normotensive inpatients, using an automated sphygmomanometer (Omega 1400), whose performance was previously evaluated by us. The results demonstrate that blood pressure monitoring in inpatients could be a useful tool in managing hypertensive patients.  相似文献   
254.
Stress ulcers are characterized by difficult management and poor prognosis. They currently represent a complication in the clinical course of other conditions, mainly shock states. The pathogenesis of stress ulcers is not well understood although the role of hypovolemia leading to energetic deprivation and insaturation of anaerobic cellular metabolism have been carefully studied. Somatostatin has been found to reduce the incidence of experimental stress ulcers. In the clinic, patients with duodenal ulcers were found to exhibit a low number of antral D cells and a significant decrease in tissue somatostatin. In a multicenter trial, patients with bleeding peptic or stress ulcers were treated with somatostatin or cimetidine plus pirenzepine. Results were favorable to the former substance on account of the time required to stop the hemorrhage and the demands for blood replacement. Thus, medical management of bleeding ulcers with somatostatin may represent an alternative to more radical surgical intervention.  相似文献   
255.
256.
Cotton (Gossypium hirsutum L.) cotyledon tissues have been efficiently transformed and plants have been regenerated. Cotyledon pieces from 12-day-old aseptically germinated seedlings were inoculated with Agrobacterium tumefaciens strains containing avirulent Ti (tumor-inducing) plasmids with a chimeric gene encoding kanamycin resistance. After three days cocultivation, the cotyledon pieces were placed on a callus initiation medium containing kanamycin for selection. High frequencies of transformed kanamycin-resistant calli were produced, more than 80% of which were induced to form somatic embryos. Somatic embryos were germinated, and plants were regenerated and transferred to soil. Transformation was confirmed by opine production, kanamycin resistance, immunoassay, and DNA blot hybridization. This process for producing transgenic cotton plants facilitates transfer of genes of economic importance to cotton.  相似文献   
257.
258.
The aim of this study was to reproductively assess the clinical and hormonal effects of a GnRH agonist (AG) and an antagonist (AN) administered during the postnatal period in domestic cats. Forty-eight male and female postnatal kittens were randomly assigned to deslorelin acetate 1.6 mg subcutaneous (AG; n = 16), acyline 33 μg/100 g subcutaneous weekly for 3 months (AN; n = 16), or control (CO; n = 16) which remained untreated. The cats were followed up (behavioral observation, physical examination, fecal sexual steroid determinations, mating test, and pregnancy diagnosis) up to puberty. Puberty was delayed (weeks) in the AG animals (62.9 ± 3.5; P < 0.01) but not in the AN (15.5 ± 1.7; P > 0.05) when they were compared with CO kittens (13.4 ± 0.4). Fifteen (15/16) of the AN and CO animals, and only 11 of 16 cats of the AG group were fertile (P > 0.1). No differences were found in body weight (P > 0.1) and measurements (P > 0.1), libido (P > 0.1) and in the appearance of side effects (P > 0.1; except a pyometra in an AG female) among groups. In both AG- and AN-treated males (testosterone; P < 0.01) and females (estradiol-17β; P < 0.01) fecal hormone concentrations were lower than in CO group during the first five postnatal weeks but not later. It is concluded that the neonatal administration of these AG and AN decreased fecal sexual steroids during the first postnatal weeks causing, the agonists but not the antagonist, a significant, reversible delay in puberty appearance.  相似文献   
259.
24 hour pressure monitoring is a newly developing technique potentially yielding important informations in hypertensive patients. Numerous automated devices are available whose performance characteristics are poorly documented. To evaluate an automated sphygmomanometer commonly used in our Division (Omega 1400, Invivo Research Laboratories), we performed a series of measurements, simultaneously recording blood pressure in the opposite arm with a common sphygmomanometer. Each measure was then repeated reversing the position of the two devices (manual and automated), thus abolishing possible differences between the two arms. We observed a mean underestimation of 1.90 mmHg of systolic pressure and of 4.82 mmHg of diastolic blood pressure by the automated device. We conclude that the device by us evaluated is not advisable in the basal blood pressure evaluation, but useful in monitoring inpatients.  相似文献   
260.
Iberian gypsum outcrops are highly fragmented and ecologically challenging environments for plant colonization. As gypsophytes occur exclusively in such habitats, they are ideal models for the study of both the effects of habitat fragmentation and selection on population genetic diversity and structure. In this study, we used amplified fragment length polymorphism (AFLP) and plastid DNA sequences to investigate the phylogeographical history of the Iberian plant Gypsophila struthium (Caryophyllaceae), a widespread endemic restricted to Iberian gypsum outcrops. Gypsophila struthium consists of two subspecies that differ in the architecture of their inflorescence and have mostly allopatric ranges. Gypsophila struthium subsp. struthium occurs in central, eastern and south‐eastern Iberia, whereas G. struthium subsp. hispanica occurs in northern and eastern areas. AFLPs revealed low but significant genetic differentiation between the subspecies, probably as a result of a recent diversification during the Pliocene–Pleistocene. In the geographical contact zone between the taxa, the Bayesian analyses revealed populations with mixed ancestries and genetic clusters predominantly of one or the other subspecies, indicating incomplete reproductive barriers between them. Plastid DNA haplotypes revealed strong geographical structure and testified to processes of isolation by distance and continuous range expansion for some haplotype clades. The Bayesian analyses of the population structure of AFLP data and nested clade phylogeographical analysis (NCPA) of plastid haplotypes revealed that the putative ancestral range corresponded to central and eastern populations of G. struthium subsp. struthium, with those lineages contributing through more recent expansion to increased genetic diversity and structure of the south‐eastern and eastern ranges of this subspecies and to the diversification of G. struthium subsp. hispanica in northern and eastern gypsum outcrops. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 654–675.  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