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271.
Overproduction of dihydrofolate reductase and gene amplification in methotrexate-resistant Chinese hamster ovary cells. 总被引:1,自引:7,他引:1 下载免费PDF全文
W F Flintoff M K Weber C R Nagainis A K Essani D Robertson W Salser 《Molecular and cellular biology》1982,2(3):275-285
Stable isolates of Chinese hamster ovary cells that are highly resistant to methotrexate have been selected in a multistep selection process. Quantitative immunoprecipitations have indicated that these isolates synthesize dihydrofolate reductase at an elevated rate over its synthesis in sensitive cells. Restriction enzyme and Southern blot analyses with a murine reductase cDNA probe indicate that the highly resistant isolates contain amplifications of the dihydrofolate reductase gene number. Depending upon the parenteral line used to select these resistant cells, they overproduce either a wild-type enzyme or a structurally altered enzyme. Karyotype analysis shows that some of these isolates contain chromosomes with homogeneously staining regions whereas others do not contain such chromosomes. 相似文献
272.
Ciumasu IM Krämer PM Weber CM Kolb G Tiemann D Windisch S Frese I Kettrup AA 《Biosensors & bioelectronics》2005,21(2):354-364
This paper presents a new, versatile, portable miniaturized flow-injection immunosensor which is designed for field analysis. The temperature-controlled field prototype can run for 6h without external power supply. The bio-recognition element is an analyte-specific antibody immobilized on a gold surface of pyramidal structures inside an exchangeable single-use chip, which hosts also the enzyme-tracer and the sample reservoirs. The competition between the enzyme-tracer and the analyte for the antigen-binding sites of the antibodies yields in the final step a chemiluminescence signal that is inversely proportional to the concentration of analyte in the given range of detection. A proof of principle is shown for nitroaromatics and pesticides. The detection limits (DL; IC20) reached with the field prototype in the laboratory was below 0.1 microg l(-1) for 2,4,6-trinitrotoluene (TNT), and about 0.2 microg l(-1) for diuron and atrazine, respectively. Important aspects in this development were the design of the competition between analyte and enzyme-tracer, the unspecific signal due to unspecific binding and/or luminescence background signal, and the flow pattern inside the chip. 相似文献
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野生与笼养绿孔雀种群的随机扩增多态DNA研究 总被引:4,自引:1,他引:4
利用随机扩增多态DNA(RAPD)技术对野生14只和笼养18只绿孔雀(Pavo muticus)个体进行了种群遗传多样性分析。用23个随机引物,野生与笼养绿孔雀分别获得161和166个扩增片段,计算发现野生与笼养绿孔雀的种群内平均相对遗传距离分别是0.0555和0.1355,两种群间的为0.1635;两种群的Shannon多样性指数平均分别是0.4348和1.0163,有显著性差异。以上分析都显示野生绿孔雀的遗传多样性很低。用UPGMA法聚类显示两个种群都是分别来源于两个家系,可据此进行繁育管理。
Abstract:Random-amplified polymorphic DNA(RAPD) was used to investigate the genetic diversity of the population of 14 wild green peafowl and 18 captive green peafowl(pavo muticus).Total of 161 and 166 bands were obtained respectively,and 23 random primers were used to amplify the genomic DNA of the wild and captive green peafowls.The average relative hereditary distance of the wild and captive green peafowls is 0.0555 and 0.1355 respectively;and the Shannon diversity index is 0.4348 and 1.0163 respectively.There is a prominent differentia between the two populations by T-Test of HO.All the analyses above show that the genetic diversity is very low in wild green peafowl.It tells us that the two populations come from two families by using UPGMA,which can be useful in the breeding management in the future. 相似文献
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对我国52种微茎类吸虫的18项成虫形态学特征进行主成分分析,结果表明:卵巢位置、子宫延伸位置等7项性状对第一主成分贡献较大,提示描述器官位置的指标是重要的分类依据。52个虫种在前三个主成分上的排序图显示应将其划分成4个亚科。 相似文献
278.
维生素C·Cu·菲咯啉系统对DNA的定位损伤 总被引:4,自引:0,他引:4
维生素C·Cu·菲咯啉系统对DNA的定位损伤柯德森,王爱国,罗广华(中国科学院华南植物研究所,广州510650)关键词活性氧;DNA;定位损伤活性氧对DNA的损伤已经被很多工作所证实”””,这种伤害是由0B”直接作用于DNA所引起的”’“。但是OH’... 相似文献
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Molecular Phylogeny of Metazoan Intermediate Filament Proteins 总被引:7,自引:0,他引:7
Andreas Erber Dieter Riemer Marc Bovenschulte Klaus Weber 《Journal of molecular evolution》1998,47(6):751-762
We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes,
the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported
here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha,
Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of data on IF proteins of vertebrates
and the results on IF proteins of Cephalochordata, Mollusca, Annelida, and Nematoda, two IF prototypes emerge. The L-type,
which includes 35 sequences from 11 protostomic phyla, shares with the nuclear lamins the long version of the coil 1b subdomain
and, in most cases, a homology segment of some 120 residues in the carboxyterminal tail domain. The S-type, which includes
all four subfamilies (types I to IV) of vertebrate IF proteins, lacks 42 residues in the coil 1b subdomain and the carboxyterminal
lamin homology segment. Since IF proteins from all three phyla of the chordates have the 42-residue deletion, this deletion
arose in a progenitor prior to the divergence of the chordates into the urochordate, cephalochordate, and vertebrate lineages,
possibly already at the origin of the deuterostomic branch. Four phyla recently placed into the protostomia on grounds of
their 18S rDNA sequences (Brachiopoda, Nemertea, Phoronida, and Platyhelminthes) show IF proteins of the L-type and fit by
sequence identity criteria into the lophotrochozoic branch of the protostomia.
Received: 2 April 1998 / Accepted: 19 June 1998 相似文献