全文获取类型
收费全文 | 4924篇 |
免费 | 432篇 |
国内免费 | 1篇 |
出版年
2022年 | 35篇 |
2021年 | 62篇 |
2020年 | 49篇 |
2019年 | 46篇 |
2018年 | 68篇 |
2017年 | 72篇 |
2016年 | 80篇 |
2015年 | 160篇 |
2014年 | 157篇 |
2013年 | 213篇 |
2012年 | 273篇 |
2011年 | 259篇 |
2010年 | 172篇 |
2009年 | 158篇 |
2008年 | 201篇 |
2007年 | 224篇 |
2006年 | 197篇 |
2005年 | 226篇 |
2004年 | 198篇 |
2003年 | 185篇 |
2002年 | 157篇 |
2001年 | 95篇 |
2000年 | 73篇 |
1999年 | 78篇 |
1998年 | 50篇 |
1997年 | 53篇 |
1996年 | 56篇 |
1995年 | 60篇 |
1994年 | 49篇 |
1993年 | 52篇 |
1992年 | 65篇 |
1991年 | 64篇 |
1990年 | 68篇 |
1989年 | 58篇 |
1988年 | 63篇 |
1987年 | 39篇 |
1986年 | 45篇 |
1985年 | 69篇 |
1984年 | 60篇 |
1983年 | 44篇 |
1982年 | 37篇 |
1981年 | 36篇 |
1980年 | 37篇 |
1979年 | 49篇 |
1978年 | 34篇 |
1977年 | 34篇 |
1976年 | 26篇 |
1974年 | 44篇 |
1973年 | 25篇 |
1971年 | 26篇 |
排序方式: 共有5357条查询结果,搜索用时 78 毫秒
11.
Acta Biotheoretica - Author continues the publication which appeared in the Acta Biotheoretica I, p. 113–132, regarding his results obtained in course of research work on superior... 相似文献
12.
Franz Frimmel 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1937,9(6-7):173-177
Ohne Zusammenfassung 相似文献
13.
Franz M. Wuketits 《Biology & philosophy》1986,1(2):191-206
Recently, biologist and philosophers have been much attracted by an evolutionary view of knowledge, so-called evolutionary epistemology. Developing this insight, the present paper argues that our cognitive abilities are the outcome of organic evolution, and that, conversely, evolution itself may be described as a cognition process. Furthermore, it is argued that the key to an adequate evolutionary epistemology lies in a system-theoretical approach to evolution which grows from, but goes beyond, Darwin's theory of natural selection. 相似文献
14.
Ulrike Rosenfellner Franz Zehetner Martin H. Gerzabek 《Soil & Sediment Contamination》2009,18(6):685-687
Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road. 相似文献
15.
Salmonella enterica serovar Typhimurium is a Gram-negative bacterium that has a significant impact on both human and animal health. It is one of the most common food-borne pathogens responsible for a self-limiting gastroenteritis in humans and a similar disease in pigs, cattle and chickens. In contrast, intravenous challenge with S. Typhimurium provides a valuable model for systemic infection, often causing a typhoid-like infection, with bacterial replication resulting in the destruction of the spleen and liver of infected animals. Resistance to systemic salmonellosis in chickens is partly genetically determined, with bacterial numbers at systemic sites in resistant lines being up to 1000-fold fewer than in susceptible lines. Identification of genes contributing to disease resistance will enable genetic selection of resistant lines that will reduce Salmonella levels in poultry flocks. We previously identified a novel resistance locus on Chromosome 5, designated SAL1 . Through the availability of high-density SNP panels in the chicken, combined with advanced back-crossing of the resistant and susceptible lines, we sought to refine the SAL1 locus and identify potential positional candidate genes. Using a 6th generation backcross mapping population, we have confirmed and refined the SAL1 locus as lying between 54.0 and 54.8 Mb on the long arm of Chromosome 5 ( F = 8.72, P = 0.00475). This region spans 14 genes, including two very striking functional candidates; CD27-binding protein ( Siva ) and the RAC -alpha serine/threonine protein kinase homolog , AKT1 ( protein kinase B , PKB ). 相似文献
16.
17.
The histologic properties of pleural adipose organs were studied in 14 newborns. These organs contain milky spots, in which lymphocytes, macrophages and plurivacuolated fat cells are present. The milky spots have a mesothelial covering, persist to the age of 9 months and seem to act as defence devices and a site of fluid exchange. 相似文献
18.
Franz Peter Fischer Christina Miltz Ingrid Singer Geoffrey A. Manley 《Journal of morphology》1992,213(2):225-240
The starling cochlea was studied with TEM at four locations along the basilar papilla to investigate gradients in morphological features over the papilla's length and width. Hair cell shape changes continuously from neural to abneural and from basal to apical. Unlike the situation in mammals, there are no distinct populations of hair cells; the previously described types (tall hair cells and short hair cells) are merely extremes in a continuum. Contacts between THC are a normal feature. Except at the base of the papilla, SHC have very large cuticular plates, suggesting a micromechanical function for these cells. In contrast to the THC, the SHC normally completely lack afferent innervation; this indicates that their function is restricted to within the basilar papilla itself. © 1992 Wiley-Liss, Inc. 相似文献
19.
Caroline S. Page Franz M. Matschinsky Paule E. Lacy Susan Conant 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,497(2):408-414
Electrophysiological studies of cultured rat pancreatic β-cells using intracellular microelectrodes show that exogenous insulin over the range of 0.1–10.0 μg/ml inhibits the electrical activity due to 27.8 mM glucose in a dose-related manner. This inhibitory effect is manifested by a mean increase of the membrane potential from about ?20 to ?30 mV and inhibition of the manner of cells impaled showing spike activity from 60 to less than 10%. The inhibitory influence of insulin is rapid occuring within 5 min for the highest level used. The results provide evidence for a negative feedback role of insulin in regulating its own release. 相似文献
20.
R Larisch K Kley S Nikolaus W Sitte M Franz H Hautzel W Tress H-W Müller 《Hormones et métabolisme》2004,36(9):650-653
Previous studies on hypothyroid subjects have indicated serious psychiatric symptoms affecting the patients' quality of life. The present prospective cross-sectional study's aim was to examine these symptoms in thyroid patients with different functional states. A total of 254 patients (age: 56 +/- 14 years [mean +/- standard deviation], 181 female, 73 male) referred to a hospital for radioiodine treatment of hyperthyroidism or for follow-up of differentiated thyroid cancer, respectively, were included. All patients underwent the twelve-item general health questionnaire, which is an instrument for detecting mood disturbances. Euthyroid and hyperthyroid patients did not differ significantly in their general health questionnaire score (11 +/- 5 vs. 11 +/- 7), nor did subclinical hyperthyroid (11 +/- 6) or subclinical hypothyroid subjects (12 +/- 5). In contrast, hypothyroid patients showed a significantly higher mean score (17 +/- 7, p < 0.001, ANOVA). Binary logistic regression revealed that hypothyroidism increases age and gender-adjusted risk for critical mood deterioration by seven-fold. Thus, hypothyroidism represents a widely underestimated functional condition that may severely affect mental health. 相似文献