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961.
962.
Summary Cell walls of Schizochytrium aggregatum and Thraustochytrium sp. were mechanically isolated and subjected to chemical analysis. On a dry weight basis the cell walls contain 21–36% carbohydrate and 30–43% protein. The principal sugar (>95%) of the Schizochytrium wall is l-galactose, while the Thraustochytrium cell wall contains l-galactose, d-galactose and xylose with l-galactose predominating. Ultrastructurally the cell walls of both organisms consist of a laminated structure which yields thin, flexible, nearly circular scales (0.5–1.1 in diameter) upon sonic disintegration. Structures presumed to be developing wall scales are found within cisternae of the Golgi apparatus in both organisms. The chemical composition and method of formation of the cell wall in these two protists is distinctly different from that found in the Saprolegniales (Oomycetes), the group with which these organisms have hitherto been aligned. 相似文献
963.
Iain M. Murray-Lyon M. O. Rake A. K. Marshall Roger Williams 《BMJ (Clinical research ed.)》1973,4(5895):770-771
Four patients with a malignant carcinoid tumour of the small bowel (three had the carcinoid syndrome) developed gangrene of the small intestine. Attention is drawn to this seldom recognized complication, as early surgery may be life saving. 相似文献
964.
Characterization of S-Adenosylmethionine: Ribosomal Ribonucleic Acid-Adenine (N6-) Methyltransferase of Escherichia coli Strain B 总被引:2,自引:1,他引:1
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Jerry E. Sipe W. Marshall Anderson Jr. Charles N. Remy Samuel H. Love 《Journal of bacteriology》1972,110(1):81-91
This study is concerned with the isolation and characterization of the enzyme, S-adenosylmethionine:ribosomal ribonucleic acid-adenine (N6−) methyl-transferase [rRNA-adenine (N6-) methylase] of Escherichia coli strain B, which is responsible for the formation of N6-methyladenine moieties in ribosomal ribonucleic acids (rRNA). A 1,500-fold purified preparation of the species-specific methyltransferase methylates a limited number of adenine moieties in heterologous rRNA (Micrococcus lysodeikticus and Bacillus subtilis) and methyl-deficient homologous rRNA. The site recognition mechanism does not require intact 16 or 23S rRNA. The enzyme does not utilize transfer ribonucleic acid as a methyl acceptor nor does it synthesize 2-methyladenine or N6-dimethyladenine moieties. Mg2+, spermine, K+, and Na+ increase the reaction rate but not the extent of methylation; elevated concentrations of the cations inhibit markedly. The purified preparations utilize 9-β-ribosyl-2,6-diaminopurine (DAPR) as a methyl acceptor with the synthesis of 9-β-ribosyl-6-amino-2-methylaminopurine. A comparison of the two activities demonstrated that one methyltransferase is responsible for the methylation of both DAPR and rRNA. This property provides a sensitive assay procedure unaffected by ribonucleases and independent of any specificity exhibited by rRNA methyl acceptors. 相似文献
965.
Pleomorphy inHyphomicrobium T37 was manipulated by the use of different carbon (C1) sources. Growth on methanol medium is characterized by the classical morphology as found inH. vulgare cells, accompanied by some cellular pleomorphy in the form of dichotomous lobing. Extensive cellular and colonial pleomorphy was observed on media containing methylamine.We thank Mrs. P. M. Scarborough and Mrs. J. Hardy for technical assistance. 相似文献
966.
967.
Linkage of cystic fibrosis locus and polymorphic DNA markers in 14 families 总被引:1,自引:0,他引:1
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![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Susan L. Naylor Don R. Barnett James M. Buchanan Jo Latimer Ken Wieder Scott Marshall Julie Gardner Carolyn R. Denning Muriel Gluckson Ricardo Pinero Henry Rendon L. Ivon Miranda Candace Kammerer Shelley M. Zansky Rose H. King Barbara H. Bowman Jean W. MacCluer 《American journal of human genetics》1986,39(6):707-712
Linkage relationships between the cystic fibrosis (CF) locus and three polymorphic DNA markers were examined in 14 families, five of which were of Hispanic origin. Tight linkage was found between the CF locus and MET (maximum lod score = 7.16 at theta = .001), and between CF and pJ3.11 (maximum lod score = 3.87 at theta = .001). We observed two recombinations between CF and collagen, yielding a maximum lod score of 0.359 at theta = .125, and one recombination in the cluster CF-MET-pJ3.11. Analysis by the seriation method indicates the order COL-pJ3.11-CF-MET. 相似文献
968.
The effect of interacting isolated rat adipocytes with small, unilammelar vesicles on insulin receptor internalization and processing was studied. Treatment of freshly isolated cells with vesicles containing phosphatidylcholine and phosphatidylserine followed by incubation in 35 mM Tris-containing buffer considerably reduced the chloroquine-induced increase in cell-associated 125I-insulin and significantly inhibited the time and insulin dependent loss of surface insulin receptors. The internal receptor pool, as measured by insulin binding to detergent solubilized adipocytes, was relatively smaller in vesicle-treated cells. Concomitant with a slower rate of receptor internalization, insulin-sensitive hexose uptake also demonstrated significantly slower kinetics of decreased response with time. These results support the conclusion that pretreatment of fat cells with phospholipid vesicles inhibits normal insulin receptor cycling. 相似文献
969.
The use of two-dimensional electrophoresis to detect mutations induced in mouse spermatogonia by ethylnitrosourea 总被引:1,自引:0,他引:1
R R Marshall A S Raj F J Grant J A Heddle 《Canadian journal of genetics and cytology》1983,25(5):457-466
Two-dimensional electrophoresis should, in theory, be a suitable method for the measurement of induced mutation rates in the germ cells of mice. Not only can the polypeptide products of a large number of genes be resolved on a single gel but the detection of mutations which lead to proteins with altered electrophoretic properties (but not necessarily altered function) is possible. Our attempts to apply two-dimensional electrophoresis to the detection of mutation in vivo have involved three stages: (i) the rapid production of gels of high resolution and reproducibility; (ii) the identification of eight interstrain protein variants and demonstration of their simple genetic basis; and (iii) a pilot experiment using the powerful germ-cell mutagen ethylnitrosourea. It was found that although interstrain protein variants could be detected and shown to be inherited in a codominant manner, induced variants were rarely detected even on high quality gels. Only 2 variants were detected among 67 offspring of male mice treated with 150 mg/kg ethylnitrosourea. This represented a mutation rate of 0.88 X 10(-4) mutations per locus per gamete. 相似文献
970.
Localisation of the human N-ras oncogene to chromosome 1cen - p21 by in situ hybridisation. 总被引:9,自引:1,他引:8
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![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The N-ras gene is a transforming gene isolated from a variety of human tumour cell lines and is a member of a family of related ras genes. Somatic cell hybrids have previously shown that the N-ras gene is located on chromosome 1. We have confirmed this localisation by in situ hybridisation to metaphase preparations of lymphocytes and localised the gene to the region 1cen - p21. A survey has found 47 reported cases of malignancy involving deletions in the short arm of chromosome 1. Fifteen of the 47 involved a deletion in this region. 相似文献