全文获取类型
收费全文 | 476篇 |
免费 | 23篇 |
国内免费 | 23篇 |
专业分类
522篇 |
出版年
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 24篇 |
2012年 | 33篇 |
2011年 | 33篇 |
2010年 | 26篇 |
2009年 | 18篇 |
2008年 | 36篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1997年 | 3篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 7篇 |
1968年 | 5篇 |
1965年 | 2篇 |
1900年 | 2篇 |
排序方式: 共有522条查询结果,搜索用时 0 毫秒
471.
V Seliger M Mácek O Skranc J Horák M Piric P Handzo J Rous Z Jirka 《Physiologia Bohemoslovaca》1979,28(1):57-64
In loading test of a representative sample of the Czechoslovak population aged 12--55 years, the authors, examined the reaction of the pulse rate and blood pressure (in watts--W) to loading on a bicycle ergometer. On increasing the submaximal load, the pulse rate rose linearly with age--more gradually in the phase of growth and along an approximately the same trend from the age of 18. The course in adult women corresponded to the course in boys aged about 13. The maximum pulse rate fell linearly in correlation to age, by about 4--5 beats for every 10 years, from 195/min in 12-year-old boys and 198/min in girls. The working capacity at pulse rate 170 (W 170) attained the maximum at 25 years (men 198, women 112 W). The systolic pressure rose non-linearly with loading. It increased more rapidly at lower loads. Children had the smallest pressure reaction and the oldest subjects the greatest. Diastolic pressure fell gradually and non-linearly with loading. The maximum blood pressure values, according to age, rose from 138/56 torr in the oldest males and from 139/57 to 182/84 torr in females. 相似文献
472.
473.
474.
J Rubes L Borkovec Z Horínová J Urbanová I Proroková L Kulíková 《Mutation research》1992,283(3):199-210
Cytogenetic examinations were carried out in 13 cattle farms, two herds of horses, one stag farm and 13 pig farms in areas with different levels of environmental contamination. The frequency of aberrant cells per 100 mitoses was 3.67 +/- 1.89 in pigs (n = 260) and 4.16 +/- 2.4 in herbivores (n = 497). This is a significant difference (p < 0.01). Ten times higher frequencies of chromatid exchanges were found in pigs. The examined herds were classified into three groups by the level of environmental contamination (satisfactory, impaired and severely impaired environment). Significant differences in aberrant cell counts were recorded between the groups of herbivorous animals. Significant differences in pigs were recorded only between herds in satisfactory and severely impaired environments. Significantly higher frequencies of aberrant cells were found in farms of herbivorous animals in the industrial area of Pardubice compared with findings in the South Moravian agricultural area (4.7% and 3.1% respectively). The effect of local contamination sources on farm environment was also investigated. A cattle farm located in the vicinity of a large chemical plant was examined five times at 6-month intervals. An autumn examination revealed significantly higher frequencies of aberrant cells compared with the spring examination. 相似文献
475.
O St?pánek J Jindrichová J Horácek V Krpata 《Journal of hygiene, epidemiology, microbiology, and immunology》1983,27(4):445-459
In the Pardubice area, the systematic examinations for Chlamydia-specific antibodies in cattle were started in 1967. In the years 1967-1978 the detectable levels of antibody to Chlamydia were demonstrated in 16.1% of 38,394 sera from cattle and in 18.6% of 5,244 sera from slinking cows. In the year 1979 the percentage of seropositivity in cattle increased significantly to 23.5% of the 4,197 sera examined. Examinations in 1980 revealed that 23.1% of 4,042 sera from cattle, 34.4% of 319 sera from slinking cows and 17.9% of 209 sera from calves were found antibody positive. Over the period from 1974 to 1978 isolates of Chlamydia organisms were obtained from 11.7% of 452 bovine slinks and from 10% of 271 dead or prematurely slaughtered calves. In the years 1979-1981 a total of 775 individuals were subjected to medical and serological examinations for Chlamydia infection using the BIOVETA group antigen. The first group of examinees included 307 farm personnel, attendants to healthy breeds of cattle. Detectable levels of antibody to Chlamydia were recorded in 1.3% of clinically healthy individuals and in 12% of the 75 healthy, randomly selected cows taken care of by this group of personnel. The second group included 280 individuals who were in charge of slinking cows or calves with chlamydial pneumonia, or who were employed in a rendering plant. A total of 7.5% of antibody-positive individuals was found in this group of examinees. Of the 439 calves attended 17.9% had serologic evidence of infection and the 30 dead calves examined were isolate-positive: sera from 176 slinking cows showed positivity in 23.8% of cases. In the third group of 188 persons serving as controls 5.3% had serologic evidence of chlamydial infection. The statistical analysis of deviations from the Gaussian variance normal curve showed neither sex-related nor inter-group differences. At the time of serologic examinations of humans the epidemiologic situation in the given area was extremely favorable. The importance of a close cooperation between the public health and veterinary service personnel (notification of abortions in cattle) and the need of a due attention of gynecologists, dermatologists and urologists are emphasized. 相似文献
476.
Jan Hejátko Hojin Ryu Gyung-Tae Kim Romana Dobe?ová Sunhwa Choi Sang Mi Choi P?emysl Sou?ek Jakub Horák Blanka Pekárová Klaus Palme B?etislav Brzobohaty Ildoo Hwang 《The Plant cell》2009,21(7):2008-2021
The development and activity of the procambium and cambium, which ensure vascular tissue formation, is critical for overall plant architecture and growth. However, little is known about the molecular factors affecting the activity of vascular meristems and vascular tissue formation. Here, we show that the His kinase CYTOKININ-INDEPENDENT1 (CKI1) and the cytokinin receptors ARABIOPSIS HISTIDINE KINASE2 (AHK2) and AHK3 are important regulators of vascular tissue development in Arabidopsis thaliana shoots. Genetic modifications of CKI1 activity in Arabidopsis cause dysfunction of the two-component signaling pathway and defects in procambial cell maintenance. CKI1 overexpression in protoplasts leads to cytokinin-independent activation of the two-component phosphorelay, and intracellular domains are responsible for the cytokinin-independent activity of CKI1. CKI1 expression is observed in vascular tissues of inflorescence stems, and CKI1 forms homodimers both in vitro and in planta. Loss-of-function ahk2 and ahk3 mutants and plants with reduced levels of endogenous cytokinins show defects in procambium proliferation and an absence of secondary growth. CKI1 overexpression partially rescues ahk2 ahk3 phenotypes in vascular tissue, while the negative mutation CKI1H405Q further accentuates mutant phenotypes. These results indicate that the cytokinin-independent activity of CKI1 and cytokinin-induced AHK2 and AHK3 are important for vascular bundle formation in Arabidopsis. 相似文献
477.
J. Horák 《Folia microbiologica》1991,36(1):3-34
Many newly synthesized proteins must be translocated across one or more membranes to reach their destination in the individual organelles or membrane systems. Translocation, mostly requiring an energy source, a signal on the protein itself, loose conformation of the protein and the presence of cytosolic and/or membrane receptor-like proteins, is often accompanied by covalent modifications of transported proteins. In this review I discuss these aspects of protein transport via the classical secretory pathway and/or special translocation mechanisms in the unicellular eukaryotic organism Saccharomyces cerevisiae. 相似文献
478.
Jin-Hui Hor Munirah Mohamad Santosa Valerie Jing Wen Lim Beatrice Xuan Ho Amy Taylor Zi Jian Khong John Ravits Yong Fan Yih-Cherng Liou Boon-Seng Soh Shi-Yan Ng 《Cell death and differentiation》2021,28(4):1379
Motor neurons (MNs) are highly energetic cells and recent studies suggest that altered energy metabolism precede MN loss in amyotrophic lateral sclerosis (ALS), an age-onset neurodegenerative disease. However, clear mechanistic insights linking altered metabolism and MN death are still missing. In this study, induced pluripotent stem cells from healthy controls, familial ALS, and sporadic ALS patients were differentiated toward spinal MNs, cortical neurons, and cardiomyocytes. Metabolic flux analyses reveal an MN-specific deficiency in mitochondrial respiration in ALS. Intriguingly, all forms of familial and sporadic ALS MNs tested in our study exhibited similar defective metabolic profiles, which were attributed to hyper-acetylation of mitochondrial proteins. In the mitochondria, Sirtuin-3 (SIRT3) functions as a mitochondrial deacetylase to maintain mitochondrial function and integrity. We found that activating SIRT3 using nicotinamide or a small molecule activator reversed the defective metabolic profiles in all our ALS MNs, as well as correct a constellation of ALS-associated phenotypes.Subject terms: Neuroscience, Pathogenesis 相似文献
479.
480.
Z Straková M Barancík D Lukácová R Angyal L Slosarcíková K Horáková 《General physiology and biophysics》1991,10(1):63-70
Monoclonal antibody against light chains of human cardiac myosin (MLC) was labelled with horseradish peroxidase. The conjugation was performed by two different methods with glutaraldehyde and periodate respectively. The binding activities of the conjugates were tested by enzyme linked immunosorbent assay (ELISA) on the microtitration plates with immobilized MLC (1-1000 ng per well). A comparison of both methods revealed their universal suitability for the preparation of conjugates as well as their applicability. The use of conjugates shortens the time needed and improves the ELISA method for MLC estimation. Specific advantages of the glutaraldehyde and the periodate method concern diverse details. 相似文献