全文获取类型
收费全文 | 788篇 |
免费 | 45篇 |
国内免费 | 105篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 21篇 |
2019年 | 20篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 29篇 |
2015年 | 26篇 |
2014年 | 39篇 |
2013年 | 47篇 |
2012年 | 32篇 |
2011年 | 40篇 |
2010年 | 35篇 |
2009年 | 54篇 |
2008年 | 59篇 |
2007年 | 55篇 |
2006年 | 43篇 |
2005年 | 55篇 |
2004年 | 46篇 |
2003年 | 28篇 |
2002年 | 15篇 |
2001年 | 18篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 8篇 |
1972年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有938条查询结果,搜索用时 15 毫秒
11.
L. Bokenes J. B. Mercer 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(4):255-267
The function of the supra-orbital salt gland was studied in the common eider duck (Somateria mollissima). The maximum salt-secreting capacity was determined in (1) wild ducks which had been living in a marine environment, (2) ducks reared in captivity on fresh water, and (3) ducks from group 2 adapted to salt water. The maximum secreting capacity was found by infusing a solution of NaCl (1000 mosmol·kg-1) at increasing rates, from 0.691 to 1.671 mosmol·min-1. Freshwater-adapted ducks secreted at a maximum rate of 0.785 mosmol·min-1 (1500 mosmol·kg-1). Adapted to salt water they increased their capacity, and the best duck secreted at a rate of 1215 mosmol·min-1 (1600 mosmol·kg-1). The best wild duck secreted at a rate of 1516 mosmol·min-1. Ducks in group 3 were used to examine the response to a hyperosmotic or an isoosmotic infusion. The amount of salt (NaCl) given per unit time was the same. Given a hyperosmotic solution their salt glands secreted at a high rate: 30 min after the infusion had stopped the ducks had excreted 94% of the sodium infused, 92.9% via the salt gland. Given an isoosmotic solution they secreted at a rate about half the infusion rate: 30 min after cessation of infusion they had excreted 73% of the sodium, 42.9% via the salt gland and the rest by the kidneys.Abbreviations
A II
angiotensin II
-
AV I
arginine vasotocin
-
ED
freshwater-adapted ducks
-
FW
fresh water
-
SD
saltwater-adapted ducks
-
SW
sea water
-
WD
wild ducks 相似文献
12.
Turkey poults were given either of two different dosages of two different gliotoxin-producing strains ofAspergillus fumigatus. Infected lung tissue was examined postmortem for the presence of gliotoxin. Gliotoxin was found in lung tissue of ten poults infected with one strain and in seven of ten poults infected with the other strain. Concentrations of gliotoxin in the tissue exceeded 6 ppm in some of the infected tissues. The concentration of gliotoxin found in infected tissue did not appear to be correlated with the dosage of organism given. Considering the pathologic changes observed in turkey poults with aspergillosis and the production of gliotoxin during the pathogenic state in turkey poults, gliotoxin is considered likely to be involved in avian aspergillosis.
Disclaimer: Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 相似文献
13.
Summary Structures identified as annulate lamellae, lamellar bodies and subsurface cisternae were found in neurons of the hyperstriatum accessorium of the avian forebrain. Annulate lamellar arrays with up to six lamellae were present in the larger somata. The lamellae were made up of fused smooth-surfaced cisternae forming pores or annuli and were surrounded by a dense filamentous to granular material. Stacks of nonfenestrated, parallel, regularly spaced cisternae, designated as lamellar bodies, also appeared in the cytoplasm. When flattened they were reminiscent of the electron dense subsurface cisternae. Continuity could be demonstrated between peripherally located subsurface cisternae and lamellar bodies. The dense filamentous to finely granular substance was also located between these structures. Annulate lamellae, lamellar bodies and subsurface cisternae were always observed in conjunction with the rough endoplasmic reticulum. The functional significance of these structural associations is considered. 相似文献
14.
Ashwini Kumar M. M. Husain Hasan Mukhtar C. R. Krishna Murti 《Journal of biosciences》1980,2(3):181-189
Glutathione-S-transferase (EC 2.5.1.18) activity was assayed in hepatic and extra-hepatic tissues of pigeons using l-chloro-2,4-dinitrobenzene
and 1,2-dichloro-4-nitrobenzene as substrates. Gluthathione-S-transferase activity towards 1-chloro-2,4-dinitrobenzene in
pigeon was in the order: kidney > liver > testes > brain > lung> heart. The enzyme activity with 1-chloro-2,4-dinitrobenzene
as substrate was 40–44 times higher in pigeon liver and kidney than that observed with 1,2-dichloro-4-dinitrobenzene as substrate.K
m values of hepatic and renal glutathione transferase with l-chloro-2,4-dinitrobenzene as substrate were 2.5 and 3 mM respectively.
Double reciprocal plots with varying reduced gluthathione concentrations resulted in biphasic curves with twoK
m values (liver 0.31 mM and 4mM; kidney 0.36 mM and 1.3 mM). The enzyme activity was inhibited by oxidized gluthathione in
a dose-dependent pattern. 3-Methylcholanthrene elicited about 50% induction of hepatic glutathione transferase activity whereas
phénobarbital was ineffective. 相似文献
15.
Henry Hurd Rusby (1855–1940) is one of the outstanding personalities in the history of the New York Botanical Garden (NYBG).
He played a significant role, not only in the founding of NYBG in 1891, but also in establishing a strong precedent of research
and exploration in the field of economic botany at the new institution. As a result of Rusby’s influence and activity, the
study of useful plants formed an important part of NYBG’s original mandate, an institutional commitment that was rejuvenated
nearly a century later, with the formation of the Institute of Economic Botany. An indefatigable researcher both in the field
and in the herbarium, Rusby left behind a voluminous corpus of published work in systematic and economic botany that is a
legacy for modern botanists and pharmacologists. 相似文献
16.
S. A. BARNETT RHONDDA G. DICKSON KATHY G. WARTH 《Zoological Journal of the Linnean Society》1980,70(4):421-430
Scent marking by deposition of urine, and the preputial glands, of adult, male, wild house mice, Mus mmmlus L., were studied and compared with those of an outbred domestic strain. The preputial glands of dominant wild mice were always heavier than those of subordinates. No dominance relationships could be established among the domestic mice. For study of scent marking each mouse was observed singly in a residential maze. Dominant wild mice marked more than the subordinates. The domestic mice scent-marked much less even than the subordinate wild mice. Subordinate wild mice spent less time than the dominant wild mice outside the nest; but the number of excursions outside the nest made by the subordinates resembled that of the dominants. Hence social status influenced the pattern of movements in a structured environment. 相似文献
17.
Summary The possibility that the somatostatin cells are derived from the neurectoderm has been questioned in avian embryos. Isotopic and isochronic transplantations of the neural primordium from quail into chick embryos were made at the vagal level (somites 1 to 7). Quail and chick cells can be distinguished by the structure of their nucleus. The somatostatin cells were characterized immunocytochemically. In no case did quail cells showing the immunological reaction originate from the neural crest. 相似文献
18.
19.
20.