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   496篇
  免费   38篇
  国内免费   26篇
  2023年   5篇
  2022年   5篇
  2021年   10篇
  2020年   9篇
  2019年   14篇
  2018年   13篇
  2017年   11篇
  2016年   21篇
  2015年   29篇
  2014年   21篇
  2013年   37篇
  2012年   35篇
  2011年   21篇
  2010年   28篇
  2009年   15篇
  2008年   22篇
  2007年   20篇
  2006年   12篇
  2005年   16篇
  2004年   14篇
  2003年   12篇
  2002年   7篇
  2001年   12篇
  2000年   8篇
  1999年   21篇
  1998年   7篇
  1997年   4篇
  1996年   4篇
  1995年   5篇
  1994年   4篇
  1993年   10篇
  1992年   5篇
  1991年   5篇
  1990年   7篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   6篇
  1983年   6篇
  1981年   7篇
  1980年   3篇
  1979年   6篇
  1978年   4篇
  1977年   5篇
  1976年   7篇
  1975年   7篇
  1973年   3篇
  1971年   8篇
  1969年   5篇
  1966年   4篇
排序方式: 共有560条查询结果,搜索用时 15 毫秒
231.
Blood samples from healthy adult Atlantic salmon fed an optimal diet in net sea pens were collected at intervals from October to May. Haematological determinations and biochemical serum analyses were carried out on 20 fish in each of seven samples. The ranges of haemato-logical values for sample means were: haematocrit 44–49%, haemoglobin 8.9–10.4 g 100ml−1, red blood cell count 0.85–1.10 × 1012 l−1, MCV 441–553 × 10−15 1, MCH 94–106 × 10−6 g, MCHC 19.4–21.7 g 100ml−1 and leucocrit 0.43–0.96%. The ranges of enzyme activities in serum, for sample means, were: alkaline phosphatase 647–988Ul−1, aspartate aminotrans-ferase 202–351 Ul−1 and alanine aminotransferase 4–8 Ul−1. The ranges of the other parameters analyzed in serum were: total protein 41.6–56.6 gl−1, albumin 18.3–24.3 gl−1, albumin/total protein ratio 39.3–44.0%, creatinine 26–46 μmol, triglycerides 2.53–4.98 μmol and cholesterol 9.3–12.8 μmol. These values are considered to be the normal ranges in healthy fish. Variations due to seasonal changes, and the clinical significance of the selected parameters, are discussed. Data showing the reproducibility of the biochemical analyses in serum are presented.  相似文献   
232.
The seasonal and chronological distributions of birth dates of 820 patients with congenital hypothyroidism due to thyroid dysgenesis were analysed in eight areas in the world. The incidence had some seasonal variations in certain areas. These observations suggest that some environmental factors cause this disease.  相似文献   
233.
This is a discussion of the reaction to the recent research article publication in the journal Protein & Cell by a group of scientists at Sun Yat‐sen University using the CRISPR/Cas9 technique on editing non‐viable human zygotes. Many commentators condemned the Chinese scientists for overstepping ethical boundaries long accepted in Western countries and accused China of having lax regulations on genomic research in general. We argue that not only did this research follow strict ethical standards and fully comply with current regulations, but China also has a well‐developed regulatory framework governing such research comparable to many developed countries. We see the reactions among Western commentators as a misunderstanding of the current situation and an expression of a lack of willingness to acknowledge China as an equal partner in the international debate about proper limits to the development of new biotechnologies.  相似文献   
234.
BackgroundThe prevalence of depressive and anxiety symptoms and their associated factors in bladder and renal cancer patients are not well evaluated in China. Given the growing attention to positive psychological constructs in the field of oncology, it is necessary to explore the effects of these constructs on depressive and anxiety symptoms. This study aims to explore the associations of psychological stress with depressive and anxiety symptoms among Chinese bladder and renal cancer patients and the mediating role of resilience in these relationships.MethodsA cross-sectional study was conducted at the First Affiliated Hospital of China Medical University in Liaoning province. 327 bladder cancer patients and 268 renal cancer patients completed questionnaires on demographic variables, the Center for Epidemiologic Studies Depression Scale, Zung Self-Rating Anxiety Scale, Resilience Scale-14, and Perceived Stress Scale-10 during the period from July 2013 to July 2014. Hierarchical linear regression analyses were performed to explore the mediating role of resilience.ResultsThe prevalence of depressive and anxiety symptoms was 78.0% and 71.3% in bladder cancer patients, and 77.6% and 68.3% in renal cancer patients. Psychological stress was positively related to depressive and anxiety symptoms, while resilience was negatively related to these symptoms. Resilience partially mediated the relations of psychological stress with depressive and anxiety symptoms.ConclusionsThe high prevalence of depressive and anxiety symptoms among Chinese bladder and renal cancer patients should receive more attention from medical institutions and government agencies. In addition to reducing depressive and anxiety symptoms, resilience development should be included in depression and anxiety prevention and treatment strategies in China.  相似文献   
235.
Combination of a 3-D scaffold with the emerging RNA interference (RNAi) technique represents the latest paradigm of regenerative medicine. In our recent paper “RNAi functionalized collagen-chitosan/silicone membrane bilayer dermal equivalent for full-thickness skin regeneration with inhibited scarring” in the journal Biomaterials, we not only demonstrated a 3-D system for siRNA sustained delivery, but also presented a comprehensive in vivo study by targeting a vital problem in skin regeneration: scarring. It is expected that further development of this kind of RNAi functionalized scaffold can provide a better platform for directing cell fates by integrating the “down-regulating” biomolecular cues into the cellular microenvironment, leading to the complete functional regeneration of skin.  相似文献   
236.

Background  

The aim of this work was to study how evenly detoxifying genes are transcribed spatially in liver tissue of fish. Ten Atlantic salmon Salmo salar were intraperitoneally injected with 50 mg/kg of the strong CYP1A inducer β-naphthoflavone and liver tissue harvested seven days later. The liver from 10 control and 10 exposed fish were split into eight sections, RNA extracted and three reference (β-actin, elongation factor 1AB (EF1AB)) and two detoxifying genes (CYP1A and GST) quantified with real-time RT-PCR. The cellular localization of the EF1AB and CYP1A mRNA in the liver of control and β-naphthoflavone treated fish was then determined by in situ hybridization (ISH) using EF1AB and CYP1A biotinylated oligonucleotide probes.  相似文献   
237.
Fifty-nine genotypes representing six genera of the True Citrus Fruit Trees Group (Aurantioideae, Rutaceae) were analyzed using AFLP technique to study their taxonomic and phylogenetic relationships. Fifteen primer combinations (out of 64 screened) were selected based on the polymorphism and quality of the bands produced by the primer and used in the present study. A total of 312 bands were obtained, of which 305 (97.8%) were polymorphic. The UPGMA tree of all genotypes was constructed based on the AFLP data using PAUP* beta version 4.0b8 software. Our AFLP molecular tree clearly confirms that the True Citrus Fruit Trees Group is monophyletic and supports the division of the group into genera mainly based on morphological characters, except that the genus Fortunella was nested within the genus Citrus cluster (as a monophyletic sub-branch). The subdivision of the genus Citrus into subgen. Papeda and subgen. Eucitrus as suggested by W. T. Swingle based on morphological characters and the point of view that C. medica, C. grandis and C. reticulata are the three basic species of the subgen. Eucitrus were also supported by our molecular data. In addition, contrary to the expectation based on morphological data, however, our molecular data demonstrated that C. ichangensis is more closely related to C. junos of the subgen. Eucitrus than to the C. hystrix of the subgen. Papeda. Furthermore, our study provided the first evidence that C. mangshanensis is basal to all the loose-skin citrus types. Finally, the taxonomic and phylogenetic relationships among the six genera and the important genotypes of the genus Citrus were dis-cussed in detail.  相似文献   
238.
T. A. Lie 《Plant and Soil》1981,61(1-2):125-134
Summary Pisum sativum ecotype fulvum forms ineffective nodules with Rhizobium strains, isolated from effective nodules of the cultivated pea in Europe. Rhizobium strains isolated from nodules of fulvum peas in Israel are fully effective on this host plant, but in association with the cultivated pea they induce nodules of poor N2-fixing activity. The distribution of these fulvum-specific Rhizobium strains is restricted to regions where the fulvum pea occurs naturally. Rhizobium strains from other geographical regions induce mainly ineffective, or partially effective nodules on fulvum plants.A wide genetic variation, with regard to symbiotic response to a standard set of Rhizobium strains, was demonstrated in the fulvum plants collected in Israel. Based on variation in N2-fixation three groups of plants can be distinguished. These plants offer the possibility for the study of host-genetic control on symbiotic nitrogen fixation.  相似文献   
239.
Red cell acid phosphatase polymorphism in Norway   总被引:1,自引:0,他引:1  
H Lie  P Teisberg 《Human heredity》1973,23(3):257-262
  相似文献   
240.
T. A. Lie 《Plant and Soil》1984,82(3):415-425
Summary Using primitive and wild pea plants from Afghanistan, Iran and Turkey, three host genes were detected, which confer resistance to nodulation by Rhizobium strains of cultivated peas from Europe. A dominant gene Sym 1 controls temperature-sensitive nodulation in pea cv. Iran. Another gene Sym 2 confers general resistance to a large number of European Rhizobium strains at all temperatures used. The degree of dominance of the latter gene is dependent on the Rhizobium strain used. A third gene Sym 4 is responsible for specific resistance to a single Rhizobium strain.  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