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61.
Brown RP 《Genetica》1997,101(1):67-74
Heterogeneous phenotypic correlations may be suggestive of underlying changes in genetic covariance among life-history, morphology,
and behavioural traits, and their detection is therefore relevant to many biological studies. Two new statistical tests are
proposed and their performances compared with existing methods. Of all tests considered, the existing approximate test of
homogeneity of product-moment correlations provides the greatest power to detect heterogeneous correlations, when based on
Hotelling's z*-transformation. The use of this transformation and test is recommended under conditions of bivariate normality.
A new distribution-free randomisation test of homogeneity of Spearman's rank correlations is described and recommended for
use when the bivariate samples are taken from populations with non-normal or unknown distributions. An alternative randomisation
test of homogeneity of product-moment correlations is shown to be a useful compromise between the approximate tests and the
randomisation tests on Spearman's rank correlations: it is not as sensitive to departures from normality as the approximate
tests, but has greater power than the rank correlation test. An example is provided that shows how choice of test will have
a considerable influence on the conclusions of a particular study.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
62.
This study describes the development of a simple, rapid and reproducible microassay for determining the intracellular LDH activity of rat hepatocytes present in a co-culture system with other cells. The procedure involves treatment of cellular homogenates with an anti-LDH antiserum that specifically inhibits the LDH activity of rat hepatocytes. The assay is performed in 96-well plates and LDH activity can be measured directly in the same wells using a colorimetric method. The difference in LDH activity values measured before and after antiserum incubation reflects the LDH content of the hepatocytes in the sample. The advantages of this method are the small number of cells required, a reduction in sample handling and the possibility of differentiating LDH activity in hepatic and non-hepatic cells. The possible applications of this technique as a parameter for biochemical data and as a test for cytotoxicity studies in co-cultures are also discussed. 相似文献
63.
Tests for departure from normality: Comparison of powers 总被引:5,自引:0,他引:5
64.
The purpose of this study was to employ the Salmonella/microsomal assay (Ames test) to investigate the mutagenic potential of a thermostable exotoxin of Bacillus thuringiensis subsp. morrisoni. Bacteria are ideal for the detection of infrequently occurring point mutations because the large number of organisms (200 to 400 million bacteria per plate) exposed to the mutagen at any one time increases the possibility of observing a random mutational event. The exotoxin used in this study was produced using the shaker flask fermentation procedure with mineral casein broth. A Petri dish method of bioassay using fresh bovine feces was used to determine the efficacy of the exotoxin against horn flies. The LD50 was found to be 5.35 μl/g of feces. Five bacterial tester strains were identified and characterized for the genetic markers described by Ames et al. (B. N. Ames et al., 1975, Mutat. Res., 31, 347–364). Appropriate doses of the B. thuringiensis supernatant, solvent or positive control were added to agar plates. The supernatant was tested at five dose levels against all five strains of bacteria. Controls of bacteria only were included for spontaneous reversions. All treatments were performed in triplicate. The numbers of revertant colonies from each set of triplicate plates were averaged and the standard deviation calculated and compared to that found with the solvent control. The negative controls, positive controls, and sterility controls all fulfilled requirements for determination of a valid test. No detectable mutagenic activity was found for the thermostable exotoxin of B. thuringiensis morrisoni. 相似文献
65.
Analysis of contingency tables under cluster sampling 总被引:2,自引:0,他引:2
66.
67.
M. Anastassova-Kristeva H. Nicoloff S. Georgiev 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1978,53(5):229-231
Summary Six varieties of Triticum monococcum were analysed by means of the nucleolar test; i.e., estimation of the maximum number of primary nucleoli per nucleus. All of the varieties exhibited 4 primary nucleoli in telophase and early interphase. Following detailed karyological analysis four SAT chromosomes in all six karyotypes were found in accordance with the maximum nucleolar number. Secondary constrictions and microsatellites were localised on the short arms of chromosome pairs 3 and 5. A new order of the chromosomes in the idiogram of Tr. monococcum is proposed. 相似文献
68.
Radial estimates and the test for sphericity 总被引:1,自引:0,他引:1
69.
Robust properties of likelihood ratio tests 总被引:2,自引:0,他引:2
70.
Tadayo Hashimoto 《Journal of microbiological methods》1983,1(2):89-98
A micromethod for the quantitative determination of the viability of Candida albicans hypae was devised which takes advantage of the dimorphic nature of C. albicans which grows exclusively in the yeast form when incubated aerobically on Sabouraud dextrose agar at 30°C. When tested by thisd method, all viable, C. albicans hyphae were recognized as microcolonies consisting of one hypha surrounded by several yeast form progeny. In contrast to this, no yeast form progeny emerged from nonviable hypae. By counting appropriate total numbers (200–400) of microcolony-forming hypae and infertile hyphae, it was possible to determine the ratio of viable to nonviable cells in a given hyphal suspension. This micromethod may be used for quantitative assessment of the candidacidal effects of various antimycotic agents or phagocytes C. albicans hyphae whose viability could not have been determined by the conventional plating technique because of the species' high propensity to clump. 相似文献