全文获取类型
收费全文 | 876篇 |
免费 | 52篇 |
国内免费 | 14篇 |
出版年
2021年 | 17篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 30篇 |
2014年 | 29篇 |
2013年 | 47篇 |
2012年 | 22篇 |
2011年 | 28篇 |
2010年 | 27篇 |
2009年 | 49篇 |
2008年 | 36篇 |
2007年 | 21篇 |
2006年 | 43篇 |
2005年 | 28篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 22篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 16篇 |
1986年 | 6篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 13篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 15篇 |
1970年 | 5篇 |
排序方式: 共有942条查询结果,搜索用时 15 毫秒
31.
Summary In submandibular glands of rabbits both adrenergic and cholinergic axons are intimately associated with parenchymal cells of the intercalary ducts and the granular tubules, lying beneath the basement membrane and often in the space between the parenchymal cell and an associated myoepithelial cell. The submandibular acini receive a less intimate and less plentiful innervation by adrenergic and cholinergic axons which remain outside the basement membrane and are still associated with Schwann cells. Occasional axons of both adrenergic and cholinergic type occur beneath the basement membrane of submandibular striated ducts in intimate association with basal parts of the cells.In the parotid glands numerous adrenergic and cholinergic axons are found beneath the basement membrane of acini and intercalary ducts in intimate association with the cells.This work has been helped by the technical assistance of Mr. P.S.A. Rowley 相似文献
32.
33.
Opsonizing effect of serum and albumin gland extracts on the elimination of human erythrocytes from the circulation of Helix pomatia 总被引:3,自引:0,他引:3
The removal of human erythrocytes of the A1 and B types from the circulation of the gastropod Helix pomatia follows an exponential curve. The elimination of the nonself particles is apparently dependent on serum opsonins as preincubation of A1 and B erythrocytes in Helix serum increases the rate of their clearance. This conclusion is supported by our finding that secondary doses of nonsensitized A1 erythrocytes injected 12–19 hr after a similar primary dose are cleared very slowly; however, the clearance rate returns to normal if erythrocytes comprising the second dose are preincubated with Helix serum. Furthermore, the elimination of second-dose A1 erythrocytes is strongly enhanced after their pretreatment with agglutinating extracts of the albumin glands from H. pomatia and Cepaea (Helix) nemoralis. On the other hand, no opsonizing effect was obtained by pre-incubating A1 erythrocytes in the agglutinating extract of the sponge Aaptos papillata. 相似文献
34.
C. ALLAN CHILD 《Zoological Journal of the Linnean Society》1978,63(1-2):133-144
A large sample of the pycriogonid Anoplodactylus portus , collected from the Pacific side of the Panama Canal Zone, contains a high percentage of gynandromorphs. The literature on aquatic arthropod gynandromorphs is outlined. The nature and variations of the sexual mosaic population are described and discussed. The several morphological differences between normal and mosaic members of the population are illustrated, and the possible origin of these gynandromorphs is discussed. 相似文献
35.
Digital image processing of the pH-sensitive dye BCECF was used to examine the effects of high [K] media on cytoplasmic pH (pHi) of individual cells within isolated rabbit gastric glands. When cells were acidified to pHi 6.5 from the resting pHi of 7.2-7.3 and then exposed to solution containing 77 mM K plus amiloride (to block Na/H exchange), recovery to pHi 7.0 was observed. This K-induced alkalinization occurred in all cell types of the gland, including cells within antral glands that were devoid of parietal cells (PC). This process was independent of extracellular Na and Cl and was unaffected by: 5 mM Ba or 200 microM bumetanide, or acute treatment with either 500 microM ouabain or 100 microM cimetidine, histamine or carbachol. SCH28080, which inhibits the PC H/K-ATPase when used in the low microM range of concentrations, blocked the K effect on pHi at 100 microM but was ineffective at 1 microM. A similar pHi recovery was also stimulated by Li, Cs (both 72 mM), and Tl (10 mM), in the order Li greater than K greater than Cs greater than Tl (all in the presence of amiloride), and these alkalinizations were also blocked by 100 microM SCH28080. Parallel experiments were performed to test the effect of these ions on 14[C]-aminopyrine accumulation, an index of acid secretion by the H/K-ATPase at the lumenal membrane of the PC. There was no correlation between the rates of cation-induced pHi recovery from an acid load and H secretion as measured by the accumulation of aminopyrine. We conclude that the K- (and Cs- and Li-) dependent pHi recovery is mediated by a novel cation/H exchange mechanism that is distinct from the PC H/K-ATPase. 相似文献
36.
37.
Teresa M. Szopa 《Journal of insect physiology》1981,27(7):441-446
Allatectomy of adult female Schistocerca gregaria prevents the normal development of the accessory reproductive glands and no secretion is produced. Development of the glands can be restored by the administration of synthetic juvenile hormone and the response is dose-dependent. A continuous supply of hormone is required for maintenance of secretory activity. In the normal developmental sequence the total protein content of the glands remains constant until the time at which vitellogenesis occurs in the terminal oöcytes. As maturation proceeds there is a linear increase in protein content of the glands. The initial increase occurs as a result of cellular changes in the glands and is then followed by an increase due to an accumulation of secretion in the lumina. 相似文献
38.
Microsurgical suppression of presumptive endocrine areas in very young embryos of Clitumnus resulted in an arrest in development, which occurred at different stages according to the operation. In most cases however. the duration of embryonic life was not reduced significanly. The repercussions of each operation type on the ecdysteroid content of the embryos were determined using a radioimmunoassay technique.Consideration of the experimental results provides some indication on the part played by each endocrine formation during the last part of embryonic development that is between dorsal closure and hatching time. Our experiments offer original evidence that the corpora allata of the embyro are of utmost importance at the stage VII3t, in initiating the normal expression of larval characteristics. 相似文献
39.
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
40.
Knopf P. M. and Soliman M. 1980. Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni. International Journal for Parasitology, 10: 197–204. The capacity of Schistosoma mansoni to complete its life cycle was compared in CD-1 mice (permissive hosts) and Sprague-Dawley rats (nonpermissive hosts) from which the pituitary gland had been removed prior to infection with cercariae. Except for a modest decrease in egg burden, none of the parameters of worm life cycle assessed were affected in hypophysectomized mice. In contrast, all these parameters were affected in hypophysectomized rats, e.g. onset of adult worm elimination was delayed, worm development improved, oviposition increased and miracidia developed. Effects of removal from rats of the thyroid/parathyroid glands on the parasite life cycle were similar to hypophysectomy; adrenalectomy or gonadectomy were without affect. Differences between thyroidectomized and thymectomized rats are discussed. It is concluded that host hormones contribute to the nonpermissive status of rats to Schistosoma mansoni infections. 相似文献