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941.
The coding and 3-downstream regions of the gene encoding the high mobility group protein HMG-I/Y from pea have been isolated, sequenced and characterised. A 795 bp pea genomic fragment containing the coding region of the pea HMG-I/Y gene with a single intron of 201 bp was isolated by PCR. The gene encodes a protein of 197 amino acid residues with four copies of the AT-hook DNA-binding motif encoded by exon 2. Southern blot analysis on genomic DNA revealed the presence of a single copy of the HMG-I/Y gene in the haploid genome. The pea HMG-I/Y gene is expressed in all organs of pea including roots, stems, leaves, flowers, tendrils and developing seeds, as determined by northern blot analysis. 相似文献
942.
Charlotte Gray 《CMAJ》1996,154(4):541-543
All parts of Canada''s health care system are facing fiscal pressures these days, but they are particularly great at Canada''s medical schools. However, Dr. David Hawkins of the Association of Canadian Medical Colleges is optimistic that all 16 of Canada''s medical schools will remain open, mainly because of the huge impact they have on health care in their local communities. “We don''t just turn out students — we raise the standard of health care in a whole community,” he says. 相似文献
943.
Charlotte Gray 《CMAJ》1996,154(8):1241-1243
When Beryl Gaffney, a Liberal member of Parliament, was told she had a brain tumour, she decided to take control of her own life. Instead of allowing the first doctor she saw to rush her to hospital, she travelled to Montreal and London, Ont., to get a second and third opinion. Then she showed neurologists in Atlanta her test results and asked which of the three options for treatment she had received coincided with their treatment recommendation. Today, she is back in the House of Commons, where she spends much of her time debating health care issues. 相似文献
944.
Super-CHO—A cell line capable of autocrine growth under fully defined protein-free conditions 总被引:1,自引:0,他引:1
Chinese Hamster Ovary (CHO) cells are widely used for the large scale production of recombinant biopharmaceuticals. Growth of the CHO-K1 cell line has been demonstrated in serum-free medium containing insulin, transferrin and selenium. In an attempt to get autocrine growth in protein-free medium, DNA coding for insulin and transferrin production was transfected into CHO-K1 cells. Transferrin was expressed well, with clones secreting approximately 1000 ng/106 cells/24h. Insulin was poorly expressed, with rates peaking at 5 ng/106 cells/24h. Characterisation of the secreted insulin indicated that the CHO cells were incompletely processing the insulin molecule. Site-directed mutagenesis was used to introduce a furin (prohormone converting enzyme) recognition sequence into the insulin molecule, allowing the production of active insulin. However, the levels were still too low to support autocrine growth. Further investigations revealed insulin degrading activity (presumably due to the presence of insulin degrading enzymes) in the cytoplasm of CHO cells. To overcome these problems insulin-like growth factor I (instead of insulin) was transfected into the cells. IGF-1 was completely processed and expressed at rates greater than 500 ng/106cells/24h. In this paper we report autonomous growth of the transfected CHO-K1 cell line expressing transferrin and IGF-1 in protein-free medium without the addition of exogenous growth factors. Growth rates and final cell densities of these cells were identical to that of the parent cell line CHO-K1 growing in insulin, transferrin, and selenium supplemented serum-free media. 相似文献
945.
Ralf Langen Jorge L. Colón Danilo R. Casimiro Timothy B. Karpishin Jay R. Winkler H. B. Gray 《Journal of biological inorganic chemistry》1996,1(3):221-225
Analysis of electron-transfer (ET) kinetics data obtained from experiments on Ru-modified proteins (azurin, cytochrome c, myoglobin) and the bacterial photosynthetic reaction center reveals that distant donor-acceptor electronic couplings depend upon the secondary structure of the intervening polypeptide matrix. The β-sheet azurin structure efficiently and isotropically mediates coupling with an exponential distance-decay constant of 1.1?Å–1. The experimentally derived distance-decay constant of 1.4?Å–1 for long-range ET in myoglobin and the reaction center suggests that hydrogen-bond couplings are weaker through α helices than across β sheets. The donor-acceptor interactions of systems with comparable tunneling energies fall into two coupling zones: the β zone (bounded by distance-decay constants of 0.9?and 1.15 Å–1) includes all the β-sheet (azurin) couplings and all but one coupling in cytochrome c; the α zone (boundaries: 1.25 and 1.6?Å–1) includes less strongly coupled donor-acceptor pairs in myoglobin and the reaction center as well as a relatively weakly coupled pair in cytochrome c. 相似文献
946.
C. Immoos Michael G. Hill Donita Sanders James A. Fee Claire E. Slutter John H. Richards Harry B. Gray 《Journal of biological inorganic chemistry》1996,1(6):529-531
The electrochemistry of a water-soluble fragment from the CuA domain of Thermus thermophilus cytochrome ba
3
has been investigated. At 25 °C, CuA exhibits a reversible reduction at a pyridine-4-aldehydesemicarbazone-modified gold electrode (0.1 M Tris, pH 8) with E° = 0.24 V vs NHE. Thermodynamic parameters for the [Cu(Cys)2Cu]+/0 electrode reaction were determined by variable-temperature electrochemistry (ΔS°rc = –5.4(12) eu, ΔS° = –21.0(12) eu, ΔH° = –11.9(4) kcal/mol;ΔG° = –5.6 (11) kcal/mol). The relatively small reaction entropy is consistent with a low reorganization energy for [Cu(Cys)2Cu]+/0 electron transfer. An irreversible oxidation of [Cu(Cys)2Cu]+ at 1 V vs NHE confirms that the CuII:CuII state of CuA is significantly destabilized relative to the CuII state of analogous blue-copper proteins.
Received: 3 June 1996 / Accepted: 26 August 1996 相似文献
947.
Evaluation of 3-ethoxy-1,2,4-dithiazoline-5-one (EDITH) as a new sulfurizing reagent in combination with labile exocyclic amino protecting groups for solid-phase oligonucleotide synthesis. 下载免费PDF全文
M Y Ma J C Dignam G W Fong L Li S H Gray B Jacob-Samuel S T George 《Nucleic acids research》1997,25(18):3590-3593
3-ethoxy-1,2,4-dithiazoline-5-one (EDITH) was recently introduced as an efficient sulfurizing reagent for solid-phase oligonucleotide synthesis. The successful syntheses were performed using standard base protecting groups (i.e. benzoyl for A and C, isobutyryl for G), which required deprotection in concentrated ammonium hydroxide at 55 degrees C for 15-18 h. We have explored the possibility of using EDITH in combination with fast deprotection chemistry(e.g. Expedite Chemistry using tert -butylphenoxy acetyl as a base protecting group). Surprisingly, poor synthesis performance was observed when syntheses were conducted with EDITH, Expedite Chemistry and standard synthesis cycle (i.e. Coupling-Thio-Cap). Potential G modification seemed to be the source of incompatibility since sequences containing no G or carrying isobutyryl- protected G residues could be synthesized with high efficiency. However, the deleterious G modification can be readily eliminated by inserting a capping step before the sulfurization reaction. Oligomers prepared with the Coupling-Cap-Thio-Cap cycle contained few phosphodiester contaminants as measured by31P-NMR, anion-exchange HPLC and MALDI-TOF mass spectrometry. In addition to reducing deprotection time, this new combination also provides a mild method for the preparation of certain phosphorothioate oligomers that may be sensitive to prolonged ammonia treatment (e.g. thioated RNAs). 相似文献
948.
DNA markers linked to a T10 loose smut resistance gene in wheat (Triticum aestivum L.). 总被引:2,自引:0,他引:2
Screening for loose smut resistance in wheat is difficult. Selecting lines with DNA markers linked to loose smut resistance would be more reliable and less costly. Molecular markers linked to a race T10 loose smut resistance gene were identified using a F6 single seed descent segregating population. A RAPD marker and a RFLP marker were located on opposite flanks of the resistance gene and were shown to be loosely linked. The RAPD marker was converted to a user friendly polymorphic SCAR marker that represented a single genetically defined locus in hexaploid wheat. Using these two bracketing markers simultaneously, the error rate for T10 resistance selection due to crossing-over was reduced to 4%. These markers can be used for a faster and more reliable selection of T10 resistant plants than previous conventional loose smut ratings. 相似文献
949.
Insulin-like growth factor I has similar mitogenic effects to insulin, a growth factor required by most cells in culture,
and it can replace insulin in serum-free formulations for some cells. Chinese Hamster Ovary cells grow well in serum-free
medium with insulin and transferrin as the only exogenous growth factors. An alternative approach to addition of exogenous
growth factors to serum-free medium is transfection of host cells with growth factor-encoding genes, permitting autocrine
growth. Taking this approach, we constructed an IGF-I heterologous gene driven by the cytomegalovirus promoter, introduced
it into Chinese Hamster Ovary cells and examined the growth characteristics of Insulin-like growth factor I-expressing clonal
cells in the absence of the exogenous factor. The transfected cells secreted up to 500 ng/106 cells/day of mature Insulin-like growth factor I into the conditioned medium and as a result they grew autonomously in serum-free
medium containing transferrin as the only added growth factor. This growth-stimulating effect, observed under both small and
large scale culture conditions, was maximal since no further improvement was observed in the presence of exogenous insulin.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
950.
Katherine A. Coerver S. M. Gray James E. Barnes Dawna L. Armstrong E. R. B. McCabe 《Histochemistry and cell biology》1997,109(1):75-86
Mammalian hexokinase types one and three (HK1 and HK3) are 100 kDa isozymes that phosphorylate glucose to glucose-6-phosphate.
HK1 is present in most tissues but is especially prominent in brain and kidney. HK3 is less well studied, but may be most
prominent in the spleen and lymphocytes. In this study, we determined the ontogeny of the expression of these isoforms in
the rat. Using immunohistochemistry, we identified HK1 and HK3 immunoreactivity in the brain, heart, kidney, liver, skeletal
muscle and spleen from gestational day 14 (E14) to 45 days after birth (P45). With the exception of the liver and spleen,
we observed a similar age- and cell-dependent staining pattern for both isoforms in all organs studied. The brain and spleen
were analyzed in more detail to identify specific regions of immunoreactivity during maturation. A transient expression of
HK1 and HK3 was noted in the cell bodies of mature neurons, including layers V and VI of the cerebral cortex and the cerebellar
Purkinje cells followed by localization to the white matter of the cerebrum and cerebellum. In the spleen, HK3 immunoreactivity
was detected postnatally and appeared to track with the infiltration of B cells. Our demonstration of changing patterns of
immunoreactivity for HK1 and HK3 in fetal and postnatal organs suggests that these HK isoforms are involved the process of
development. We speculate that HK1 and HK3 share a complex interaction during development of these organs and regulate glucose
metabolism at multiple levels during development.
Accepted: 16 May 1997 相似文献