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91.
Caroline E. G. Tutin Richard J. Parnell Lee J. T. White Michel Fernandez 《International journal of primatology》1995,16(2):53-76
We analyzed data from 373 fresh nest-sites (containing 2435 nests) of lowland gorillas (Gorilla g. gorilla)during a 4-year period in the Lopé Reserve, Gabon, to determine whether the observed variability in nest building was due
to environmental influences. We recognized and defined seven types of nest in terms of the degree of construction and the
raw materials used. Overall, nests built on the ground from herbaceous plants are the most common type (40%), followed by
tree nests (35%). Frequencies of the different nest-types vary significantly between eight habitat-types. In habitat-types
with high densities of understory herbs, ground nests predominated, but when herbs were rare, the majority of nests were in
trees. A general preference for sleeping in herbaceous ground nests is indicated since trees are abundant in all habitat-types,
except savanna. The frequency of nesting in trees shows a significant positive correlation with rainfall, but effects of climate
are confounded by seasonal variation in use of different habitat-types. When elephants were attracted to the same localized
food sources as gorillas, many tree nests were built even when herbs were available. We conclude that different nest-types
reflect a variety of solutions to maximize comfort, depending on available raw materials and the probability of rainfall or
disturbance by elephants or both factors. Nests are a powerful tool for population censuses and demographic studies of great
apes, but problems exist in interpreting data on lowland gorilla nests. Results from this analysis show that only a third
of nest-sites accurately reflects group size (of weaned individuals) and that 26% of all gorilla nest-sites could be mistaken
for those of chimpanzees, as all nests, or all those visible from a transect, were in trees. Gorilla nests at Lopé were nonrandomly
distributed with respect to habitat-types, and nest construction varied seasonally, thereby introducing sources of bias to
transect nest counts. We discuss these problems and ones related to assessing the decay rate of nest-sites and make recommendations
relevant to census work. 相似文献
92.
Subnucleolar location of fibrillarin and variation in its levels during the cell cycle and during differentiation of plant cells 总被引:5,自引:0,他引:5
The nucleolar protein fibrillarin has been studied in onion cells; it is detected as an Mr 37,000 protein by immunoblotting using a human autoimmune serum. Quantitative immunoelectron microscopy showed that most fibrillarin is localized in the transition zone between the fibrillar center (FC) and the dense fibrillar component (DFC) as well as in the priximal zone of the DFC, where the labeling shows a gradual decrease out-ward until it reaches insignificant levels in the distal zone of the DFC. Thus, fibrillarin is not uniformly distributed throughout the DFC of plant cells. This result supports the hypothesis that the morphologically homogeneous DFC may not be uniform in function; it is also in agreement with the hypothesized vectorial flow of ribosome biogenesis through the same compartments. Data are also presented showing that the amount of fibrillarin increase when nucleolar activity increases in G2, and probably decreases when nucleolar activity decreases during differentiation. 相似文献
93.
During early embryogenesis of the nematode Parascaris univalens (2n=2) the processes of chromatin diminution and segregation of the germ and somatic cell lineages take place simultaneously. In this study we analyzed the nucleolar cycle in early embryos, both in germinal and somatic blastomeres, by means of silver staining and antibodies against the nucleolar protein fibrillarin. We observed an identical nucleolar cycle in both types of blastomeres, hence, the chromatin diminution process has no effect on the nucleolar cycle of somatic blastomeres. We report the existence of outstanding differences between this cycle and those previously reported during early embryogenesis of other species. There is a true nucleolar cycle in early embryos that shows a peculiar nucleolar disorganization at prophase, and a preferential localization of prenucleolar bodies only on the euchromatic regions during nucleologenesis. Moreover, fibrillarin does not form a perichromosomal sheath in metaphase or anaphase holocentric chromosomes, probably owing to their special centromeric organization. The number and location of nucleolus organizer regions (NORs) in the chromosomal complement have been determined using silver impregnation, chromomycin A3/distamycin A staining, and fluorescent in situ hybridization using an rDNA probe. There are only two NORs, one per chromosome, and these are lost in blastomeres after chromatin diminution. Moreover, the constant presence of two nucleoli in somatic blastomeres suggests that NORs are not affected during the fragmentation of euchromatic regions when this process occurs. 相似文献
94.
95.
96.
Differential effects of five types of antipathogenic plant peptides on model membranes 总被引:2,自引:0,他引:2
Jos Manuel M. Caaveiro Antonio Molina Juan M. Gonzlez-Maas Pablo Rodríguez-Palenzuela Francisco García-Olmedo Flix M. Goi 《FEBS letters》1997,410(2-3)
The effects of five antipathogenic plant peptides, wheat α-thionin, potato PTH1 defensin, barley LTP2 lipid transfer protein, and potato tuber DL1 and DL2 defensins, have been tested against phospholipid vesicles (liposomes). Wheat thionin very actively induces aggregation and leakage of negatively charged vesicles. LTP2 displays the same activities, although to a limited extent. Under certain conditions PTH1 and DL2 induce vesicle aggregation, but not leakage. Potato defensin DL1 failed to show any effect on liposomes. The same peptides have been assayed against a plant pathogenic bacterium, both the membrane-active and -inactive compounds having efficient antibacterial action. 相似文献
97.
The mangroves of Kerala on the south-west coast of India are fast disappearing due to land reclamation and other anthropogenic
disturbances. There are very few ecosystem level studies made in these much threatened biotopes in Kerala. The present study
involves the measurement of heavy metals in the mangrove flora and sediments of three mangrove habitats along the Kerala coast.
Sampling was carried out for a period of one year at bi-monthly intervals, with concentrations of Fe, Mn, Cu,Zn,Pb and Co
analysed using atomic absorption spectrophotometry. An appreciable variation was observed in metal concentrations indifferent
mangrove species. Cu, Zn and Pb were found to be in higher concentrations in Avicennia officinalis whereas higher levels of
Fe, Mn and Co were observed in the species Barringtonia racemosa. The analysis of heavy metals indicated a high level of metal
pollutants such as Fe, Cu, Zn and Pb in the mangrove habitats of Quilon and Veli compared to the relatively uncontaminated
areas of Kumarakom.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
98.
Cecilia Ballaré Marcela Barrio Paula Portela Jose Mordoh 《Cancer immunology, immunotherapy : CII》1995,41(1):15-22
FC-2.15 is a murine IgM monoclonal antibody (mAb) that recognizes a cell-surface antigen (Ag2.15) expressed in most tumor-proliferating cells of human breast carcinomas and other neoplasias. In this study the cytotoxic ability of mAb FC-2.15, its cell-surface binding properties and endocytosis in Ag2.15-expressing (Ag2.15+) cells were investigated. A51Cr-release assay was used to test the FC-2.15-mediated cytotoxicity. When human serum was used as source of complement, FC-2.15 exerted a strong cytotoxic effect against human Ag2.15+ cells such as MCF-7 (breast cancer cell line), primary breast carcinoma cells, polymorphonuclear leukocytes and chronic myeloid leukemia cells. The mAb concentration range was 1–50 g/ml. Cytotoxicity was completely abolished when complement was inactivated. Only 3.8±2.9% of MCF-7 cells survived the treatment with FC-2.15 in the presence of human serum. A flow-cytometry assay was performed to study the Ag2.15 expression of the surviving cells and they were found to be Ag2.15–. FC-2.15 did not mediate antibody-dependent cell cytotoxicity when different effector cells were used. Scatchard analysis with125I-FC-2.15 on MCF-7 cells demonstrated an affinity constant of 6.9×107 M–1 and 2.8×106 antigenic sites/cell.125I-FC-2.15 was internalized to cytoplasmic vesicles reaching a maximum of 27% after 6 h incubation, followed by the release of labeled degradation products to the supernatant. FC-2.15 appears to exert its cytotoxic effect mainly in the presence of human complement, it reacts with intermediate affinity with a high-density surface antigen, and it is slowly internalized by Ag2.15+ cells. 相似文献
99.
The role of diet in personal health maintenance is important whether a person is trying to stay healthy or to treat diet-related diseases such as hypercholesterolemia, hypertension, diabetes mellitus or obesity. Dietary recommendations include limiting fat to 30% and protein to 20% of total calories, with the remaining 50% coming from carbohydrate. Maintaining dietary changes for long periods is very difficult for many persons. Specific self-management skills may ease the task. 相似文献
100.
Antonio P. Linares Stuart H. Cohen Elliot Goldstein Alan D. K. Kelley Toby K. Eisenstein 《The Western journal of medicine》1984,141(2):203-205
Salmonella thompson, a common pathogen of poultry, has received scant attention as a cause of human gastroenteritis. At least 45 persons were infected with S thompson in Sacramento, California, after eating at a chicken restaurant and 38 became symptomatic. Ten required admission to hospital, and all were treated with antibiotics and improved. In 19 cases cultures of stool specimens for S thompson over a 60-day period showed slower but statistically insignificant differences in salmonellal elimination in 7 patients who received antibiotics when compared with 12 who were untreated. We report this outbreak to increase awareness of the virulence and prevalence of gastroenteritis due to S thompson. 相似文献