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961.
A preference for bushy evergreen undergrowth determines both the local and the general distribution of Cossypha natalensis. The lack of such undergrowth makes equatorial rain-forests unsuitable. Tropical and subtropical evergreen forests provide excellent conditions from this point of view, and they are thus the main habitat type from which C. natalensis has secondarily extended into tropical and subtropical deciduous forests with evergreen undergrowth.
Adult birds remain in or close to their territories throughout the year. First-year birds undertake longer movements during the winter. Breeding territories are relatively small, from 2,500 up to (exceptionally) 10,000 square yards (2,100-8,400 sq. m).
Breeding begins in October. Both sexes build the nest, but only the female incubates. In southern Africa there is one brood a year, and the care of the offspring is protracted. The juvenile moult begins in the third and ends in the sixth month; adults have only one (post-breeding) moult a year.
The begging behaviour of the young is somewhat different from that of most other turdine birds, and is considered to be more primitive. The ontogeny of the adult displays is described as observed in young birds kept in captivity.
The development of vocal behaviour is described. Special attention is given to the different functional forms of the song, and to two of its special features, imitation and a tonal quality termed vox humana. 相似文献
Adult birds remain in or close to their territories throughout the year. First-year birds undertake longer movements during the winter. Breeding territories are relatively small, from 2,500 up to (exceptionally) 10,000 square yards (2,100-8,400 sq. m).
Breeding begins in October. Both sexes build the nest, but only the female incubates. In southern Africa there is one brood a year, and the care of the offspring is protracted. The juvenile moult begins in the third and ends in the sixth month; adults have only one (post-breeding) moult a year.
The begging behaviour of the young is somewhat different from that of most other turdine birds, and is considered to be more primitive. The ontogeny of the adult displays is described as observed in young birds kept in captivity.
The development of vocal behaviour is described. Special attention is given to the different functional forms of the song, and to two of its special features, imitation and a tonal quality termed vox humana. 相似文献
962.
Dr. Tibor Rajhathy 《Chromosoma》1971,35(2):206-216
The same karyotype which was described previously in A. ventricosa plants from Oran, Algeria was found in plants from Cyprus and in most of the plants from the Apsheron Peninsula, U.S.S.R. This karyotype, which consists of subterminal chromosomes, was designated C
v
1
. In the karyotype of about one-third of the Apsheron plants a single pair of submedian chromosomes replaced a pair of long subterminals. This karyotype was designated C
v
2
. The chromosomes formed 7II at meiosis in both C
v
1
C
v
1
and C
v
1
C
v
2
hybrids regardless of geographic origin. A heteromorphic bivalent was apparent in PMCs in the C
v
1
C
v
2
hybrids. A pericentric inversion was postulated as the origin of the submedian pair, the C
v
2
C
v
2
karyotype being the inversion homozygote. The absence of duplication-deficiency gametes was inferred from the good fertility of the heterozygote. Members of the heteromorphic pair were transmitted in equal proportion and the segregates C
v
1
C
v
1
, C
v
1
C
v
2
and C
v
2
C
v
2
were equally fertile; thus the inversion did not handicap reproduction. The small contemporary colonies of A. ventricosa, with peripheral locations and vast distances between them, because of the full homology and interfertility, are considered remnants of a formerly large central population.Contribution No 282 from the Research Station, Central Experimental Farm, Ottawa, Ontario.This paper is dedicated to the memory of Dr. Barna Györffy, whose untimely death on August 5, 1970 ended a distinguished career that was an example of integrity and scholarship to a troubled generation of Hungarian geneticists. 相似文献
963.
964.
965.
966.
Tibor Kmeť 《Bulletin of mathematical biology》1996,58(5):957-982
A mathematical model of the nitrogen transformation cycle in an aquatic environment is studied. Using Pontryagin's maximum
principle, a preferential utilization of ammonium to nitrate by phytoplankton is explained and verified by experimental data.
A multiparameter bifurcation is given. The model was found to have four types of equilibrium sets. It is shown that a Hopf
bifurcation may occur. 相似文献
967.
Tibor Hartel 《Biologia》2008,63(3):439-443
This study presents long-term fluctuation, within pond distribution and mortality of egg masses in a population of Rana dalmatina reproducing in a permanent semi-natural pond in Romania. The average number of egg masses per year was 410 (SD = 114.56,
min.-max. = 265–581). The mean spawning duration (days) was 26.72 (SD = 5.53). The egg mass distribution was not constant
during the years. The long-term change in the distribution of egg masses can be related to changes in the reed cover (pond
variable) and landscape structure, i.e. the presence of the forest and a pasture between the pond and the forest. There was
a reduction in the number of dead egg masses during the study period. We suggest that the maintenance of the connectivity
with the forest and the variable amount of reed assure the main aquatic and terrestrial habitats for the agile frogs. This
will allow agile frogs to shift breeding habitats in this area according to their ecological needs and find safe terrestrial
habitats for summering and wintering. 相似文献
968.
969.
J. A. Werner Stefan Gottschlich Benedikt J. Folz Tibor Goeroegh Burkard M. Lippert J.-D. Maass Heinrich Rudert 《Cancer immunology, immunotherapy : CII》1997,44(2):112-116
p53 antibodies are a new serological parameter of unknown potential in patients with malignancies. Their occurrence has been
described in various types of cancer patients. The mechanism underlying the immunization process is still unclear. We investigated
the incidence of p53 serum antibodies in 143 head and neck cancer patients with an enzyme-linked immunosorbent assay. The
post-therapy course of two matched study groups (n = 38 each), one p53-antibody-seropositive and one p53-antibody-seronegative, was followed up for 24 months. Thirty-nine head
and neck cancer patients (27.3%) were seropositive for p53 antibodies. During the follow-up, the p53-antibody-seropositive
patients accounted for more local tumor recurrences (n = 12 versus n = 8) and more tumor-related deaths (n = 11 versus n = 5) than did seronegative patients, and second primary tumors (n = 9 versus n = 0) occurred exclusively in seropositive patients. In total, therapy failures (recurrences, tumor-related deaths,
second primaries) were observed in 17/38 cases (44.7%) in the p53-antibody-seropositive group and in 8/38 cases (21.1%) in
the p53-antibody-seronegative group. These results, after a follow-up of 2 years, seem to indicate a prognostic value of p53
serum antibodies for therapy failure in patients with head and neck cancer.
Received: 5 December 1996 / Accepted: 4 January 1997 相似文献
970.