全文获取类型
收费全文 | 5270篇 |
免费 | 365篇 |
国内免费 | 4篇 |
出版年
2023年 | 44篇 |
2022年 | 79篇 |
2021年 | 166篇 |
2020年 | 87篇 |
2019年 | 100篇 |
2018年 | 151篇 |
2017年 | 131篇 |
2016年 | 165篇 |
2015年 | 227篇 |
2014年 | 244篇 |
2013年 | 376篇 |
2012年 | 402篇 |
2011年 | 349篇 |
2010年 | 237篇 |
2009年 | 180篇 |
2008年 | 234篇 |
2007年 | 234篇 |
2006年 | 213篇 |
2005年 | 198篇 |
2004年 | 156篇 |
2003年 | 153篇 |
2002年 | 134篇 |
2001年 | 83篇 |
2000年 | 59篇 |
1999年 | 66篇 |
1998年 | 32篇 |
1997年 | 43篇 |
1996年 | 31篇 |
1995年 | 31篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 56篇 |
1991年 | 55篇 |
1990年 | 60篇 |
1989年 | 53篇 |
1988年 | 43篇 |
1987年 | 42篇 |
1986年 | 56篇 |
1985年 | 49篇 |
1984年 | 56篇 |
1983年 | 39篇 |
1982年 | 39篇 |
1981年 | 34篇 |
1979年 | 39篇 |
1978年 | 23篇 |
1977年 | 34篇 |
1976年 | 34篇 |
1975年 | 39篇 |
1974年 | 38篇 |
1972年 | 24篇 |
排序方式: 共有5639条查询结果,搜索用时 171 毫秒
141.
Multiple immunoreplica Technique: screening for specific proteins with a series of different antibodies using one polyacrylamide gel 总被引:12,自引:0,他引:12
A simple method for immunological identification of proteins resolved electrophoretically is presented. Proteins from one polyacrylamide gel can be subjected to a series of electrophoretic transfers to nitrocellulose paper (partial “western-blots”), providing several replicas of the gel. Each replica can be reacted with a series of different antisera (at least three), where the preceding antibody is removed by treatment with pH 2.2. The antigen-antibody complexes are visualized using 125I-Protein A. Reactivity and antigenic specificity of proteins immobilized on nitrocellulose paper is not affected by repeated incubations and low pH treatments. Identical size of the replicas and superimposable profiles of proteins detected by antibodies allow a precise localization of particular polypeptides in the original gel. 相似文献
142.
A new technique for studying the effect of insulin on protein degradation is reported. The method is based on measuring the parallel release of a reutilizable and a nonreutilizable amino acid from muscle protein. Animals are prelabeled in vivo with [Me-3H]methionine which labels both the nonreutilizable 3-methylhistidine and the reutilizable methionine of tissue protein. The data presented show that insulin has only a trivial effect on the loss of 3-methylhistidine from muscle protein, while it substantially diminishes the efflux of methionine. The analysis of muscle protein confirms the observation that insulin causes the reincorporation of methionine and has a minimum effect on the loss of 3-methylhistidine. This supports the view that the major inhibitory effect of insulin on gluconeogenesis is the diversion of the flow of amino acids away from the gluconeogenesis pathway back toward protein synthesis. 相似文献
143.
A new antifungal antibiotic named acmycin was isolated from a soil streptomycete. Detailed comparative taxonomic studies showed
that the organism differed from three related species of streptomycetes. The organism was referred to asStreptomyces sp. AC2. The isolated antibiotic appears to be of polyene nature. 相似文献
144.
A soil actinomycete hydrolyzed collagen extracted from bovine Achilles tendon, calf skin, carp swim-bladder and rat tail tendon.
Glucose, mannose, aspartic acid and asparagine increased its collagenolytic activity which was optimum at 28 °C and at pH
7.2 – 7.5. Metallic ions, NaEDTA, cysteine, 4-chloromercuribenzoate, glutathione and sodium azide were inhibitory. 相似文献
145.
FBJ murine osteosarcoma virus: identification and molecular cloning of biologically active proviral DNA 总被引:125,自引:8,他引:117 下载免费PDF全文
A 12.0-kilobase EcoRI restriction fragment containing FBJ murine osteosarcoma virus (FBJ-MSV) proviral DNA was identified in FBJ-MSV-transformed nonproducer rat cells and molecularly cloned in bacteriophage Charon 30 (lambda FBJ-1). A 5.8-kb HindIII fragment containing the entire FBJ-MSV proviral DNA was isolated from lambda FBJ-1 and subsequently subcloned in plasmid pBR322 (pFBJ-2). The DNA from recombinant plasmid pFBJ-2 was able to induce morphological transformation of rat fibroblasts in tissue culture. Transfected cells contained the p55 and p39 antigens specific for cells transformed by FBJ-MSV (T. Curran and N. M. Teich, J. Virol. 42:114-122, 1982). The organization of the FBJ-MSV provirus was analyzed by restriction endonuclease mapping, and a region of nonhomology with the helper virus was delineated. Sequences specific for this region (presumably the viral fos gene) were subcloned and used as a probe to identify related sequences present in the normal genomes of cells from a variety of mammalian species (cellular fos). A single-size (3.4 kilobases long) class of RNA hybridizing to the viral fos probe was identified in FBJ-MSV-transformed cells. 相似文献
146.
Analysis of the env gene of a molecularly cloned and biologically active Moloney mink cell focus-forming proviral DNA. 总被引:42,自引:35,他引:7 下载免费PDF全文
A biologically active molecular clone of BALB/Moloney mink cell focus-forming (Mo-MCF) proviral DNA has been reconstructed in vitro. It contains the 5' half of BALB/Moloney murine leukemia virus (Mo-MuLV) DNA and the 3' half of BALB/Mo-MCF DNA. The complete nucleotide sequence of the env gene and the 3' long terminal repeat (LTR) of the cloned Mo-MCF DNA has been determined and compared with the sequence of the corresponding region of parental Mo-MuLV DNA. The substitution in the Mo-MCF DNA encompasses 1,159 base pairs, beginning in the carboxyl terminus of the pol gene and extending to the middle of the env gene. The Mo-MCF env gene product is predicted to be 29 amino acids shorter than the parental Mo-MuLV env gene product. The portion of the env gene encoding the p15E peptide is identical in both viral DNAs. There is an additional A residue in the Mo-MCF viral DNA in a region just preceding the 3' LTR. The nucleotide sequence of the 3' LTR of Mo-MCF DNA is similar to that of the 5' LTR of BALB/Mo-MuLV DNA with the exception of two single base substitutions. We conclude that the sequence substitution in the env gene is responsible for the dual-tropic properties of Mo-MCF viruses. 相似文献
147.
Girish Chandra 《BioControl》1980,25(2):187-192
Three new techniques of rearing dryinids parasitising rice hoppers were developed, namely, laboratory rearing technique for
detailed observations, device for transporting and rearing field-collected hoppers to estimate percentage parasitism and a
breeding technique.
Résumé Trois nouvelles techniques d’élevage de dryiinides parasites des cicadelles du riz ont été mises au point. L’une pour l’élevage en laboratoire en vue d’observations précises, un système pour le transport et l’élevage de cicadelles récoltées dans la nature afin d’évaluer le pourcentage de parasitisme et une technique d’élevage permanent.相似文献
148.
Mureins were isolated from two strains ofXanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70–95 % and the amino acid and amino sugar components (glutamic acid, alanine, meso-diaminopimelic acid, muramio acid and glucosamine) were present at the molar ratio of 1: 1.9: 1: 1.12: 0.85. The bacterium secreted a copious amount of slime which masked its surface structure. The slime was composed of densely interwoven network of filamentous material originating from the cell surface and extended into the medium without any discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formation of bacterial cells. 相似文献
149.
150.