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11.
Amy M. LaFountain Shannon Cawley Steven J. Schwartz Richard O. Prum 《Archives of biochemistry and biophysics》2010,504(1):142-153
Recent advances in the fields of chromatography, mass spectrometry, and chemical analysis have greatly improved the efficiency with which carotenoids can be extracted and analyzed from avian plumage. Prior to these technological developments, Brush (1968) [1] concluded that the burgundy-colored plumage of the male pompadour Cotinga Xipholena punicea is produced by a combination of blue structural color and red carotenoids, including astaxanthin, canthaxanthin, isozeaxanthin, and a fourth unidentified, polar carotenoid. However, X. punicea does not in fact exhibit any structural coloration. This work aims to elucidate the carotenoid pigments of the burgundy color of X. punicea plumage using advanced analytical methodology. Feathers were collected from two burgundy male specimens and from a third aberrant orange-colored specimen. Pigments were extracted using a previously published technique (McGraw et al. (2005) [2]), separated by high-performance liquid chromatography (HPLC), and analyzed by UV/Vis absorption spectroscopy, chemical analysis, mass spectrometry, nuclear magnetic resonance (NMR), and comparison with direct synthetic products. Our investigation revealed the presence of eight ketocarotenoids, including astaxanthin and canthaxanthin as reported previously by Brush (1968) [1]. Six of the ketocarotenoids contained methoxyl groups, which is rare for naturally-occurring carotenoids and a novel finding in birds. Interestingly, the carotenoid composition was the same in both the burgundy and orange feathers, indicating that feather coloration in X. punicea is determined not only by the presence of carotenoids, but also by interactions between the bound carotenoid pigments and their protein environment in the barb rami and barbules. This paper presents the first evidence of metabolically-derived methoxy-carotenoids in birds. 相似文献
12.
13.
Z Z Chen G P Schwartz L Zong G T Burke J D Chanley P G Katsoyannis 《Biochemistry》1988,27(16):6105-6111
A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins. 相似文献
14.
15.
M Schwartz 《CRC critical reviews in biochemistry》1987,22(2):89-110
Injury of an axon leads to at least four independent events, summarized in Figure 1: first, deprivation of the nerve cell body from target-derived or mediated substances, which leads to a derepressed or a permissive state; second, disruption of anterograde transport, with a resultant accumulation of anterogradely transported molecules; third, environmental response with possible consequent changes in constituents of the extracellular matrix and substances secreted from the surrounding cells; and fourth, appearance of growth inhibitors and modified protease activity. It seems that the first three of these events are obligatory, but not sufficient, i.e., they lead to a growth state only if the cell body is able to respond to the injury-induced signals from the environment (a and b). The regenerative state is characterized by alterations in protein synthesis and axonal transport and by sprouting activity. The subsequent elongation of the growing fibers depends on a continuous supply of appropriate growth factors. These factors are presumably anchored to the appropriate extracellular matrix that serves as a substratum for elongating fibers. It should be mentioned that the proliferating nonneuronal cells have a conducive effect on regeneration by forming a scaffold for the growing fibers. Accordingly, the lack of regeneration may stem from a deficiency in the ability of glial cells to provide the appropriate soluble components or from insufficient formation of extracellular matrix. In this respect, one may consider regeneration of an injured axon as a process which involves regeneration of both the nonneuronal cells and the supported axons. The regeneration of glial cells may fulfill the rules which are applied to regeneration of any other proliferating tissue. Furthermore, the processes of regeneration in the axon and the glial cells are mutually dependent. Perhaps the triggering factors provided by the nonneuronal cells affect the nonneuronal cells themselves by modulating their postlesion gliosis and thereby inducing their appropriate activation. In such a case, regeneration of nonneuronal cells may resemble an autocrine type of regulation that exists also during ontogeny. The growth regulation is shifted back to the paracrine type upon neuronal maturation or cessation of axonal growth. When the elongating fibers reach the vicinity of the target organ, they are under the influence of the target-derived factors, which guide the fibers and eventually cease their elongation. 相似文献
16.
Populations of the vernal cladoceranDaphniopsis ephemeralis are found in woodland ponds throughout southern Ontario. The species reproduces by cyclic parthenogenesis, and genotype frequencies
at allozyme loci are ordinarily in good agreement with Hardy-Weinberg expectations. Occasional heterozygote deficiencies are
apparently the consequence of admixture of ephippial hatchlings produced in temporally separated bouts of sexual reproduction.
Considerable heterogeneity in genotypic frequencies exists among local populations in southwestern Ontario, indicating that
gene flow among populations is restricted. Inbreeding coefficients suggest that populations receive an average of 0.3 migrants
per generation. The completion of a sexual life cycle is made possible despite the brief persistence of populations by the
emergence of males from ephippial eggs and by the production of equal numbers of male and female progeny in the first parthenogenetic
brood. 相似文献
17.
Characterization of Erwinia chrysanthemi extracellular proteases: cloning and expression of the protease genes in Escherichia coli. 总被引:19,自引:11,他引:8 下载免费PDF全文
Erwinia chrysanthemi, a phytopathogenic enterobacterium, secretes three antigenically and structurally distinct proteases, A, B, and C and produces a protease inhibitor, a low-molecular-weight, heat-stable protein which remains mostly intracellular and which binds specifically to the A, B, and C proteases. The structural genes for proteases A, B, and C and for the inhibitor are clustered on a ca. 40-kilobase DNA fragment present in cosmid pEW4. Escherichia coli strains harboring pEW4 secrete the three proteases into the medium during the exponential phase of growth, without intracellular accumulation and in the absence of detectable cell lysis. An 8.5-kilobase EcoRI fragment derived from the cosmid encodes proteases B and C and the inhibitor as well as functions involved in the synthesis or secretion (or both) of the proteases. The inhibitor is not required for protease synthesis or secretion. 相似文献
18.
Co-purification and characterization of ATP-sulfurylase and adenosine-5'-phosphosulfate kinase from rat chondrosarcoma 总被引:1,自引:0,他引:1
D H Geller J G Henry J Belch N B Schwartz 《The Journal of biological chemistry》1987,262(15):7374-7382
The two sulfate-activating enzymes, ATP-sulfurylase (EC 2.7.7.4) and adenosine-5'-phosphosulfate kinase (adenylylsulfate kinase, EC 2.7.1.25), were each purified about 2000-fold from crude rat chondrosarcoma homogenate. Throughout a purification protocol which included Sephacryl S-300 gel filtration, DEAE-Sephadex ion exchange, hydroxylapatite, and ATP-agarose affinity chromatography, these two activities consistently co-purified. ATP-sulfurylase and adenosine-5'-phosphosulfate kinase each showed a pH optima of 7.0-7.4 and a bimodal temperature optima of 46 and 52-54 degrees C. Both activities preferred Mg2+ as their divalent cation source over Mn2+, Co2+, or Zn2+. The apparent Km values determined for adenosine 5'-phosphosulfate in both assays was 1-5 microM; the Km for pyrophosphate in the sulfurylase reaction was 40 microM and for ATP in the kinase reaction was 5 mM. Gel electrophoresis indicated major bands at Mr = 160,000 in nondenaturing systems and 35,000-37,000 and 60,000 under dissociative conditions, whereas gel filtration of the most highly purified fractions yielded a coincident peak in the molecular weight range 260,000. 相似文献
19.
S M Goldstein C E Kaempfer D Proud L B Schwartz A M Irani B U Wintroub 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(8):2724-2729
Using a high performance liquid chromatography assay that detects the cleavage of the C-terminal leucine from angiotensin I, we have identified a carboxypeptidase activity in mast cells from human lung and in dispersed mast cell preparations from human skin. The enzyme activity was detected in a preparation of dispersed human mast cells from lung of greater than 99% purity and was released with histamine after stimulation with goat anti-human IgE. In nine preparations of dispersed human mast cells from lung of 10 to 99% purity, net percentage of release of carboxypeptidase correlated with the release of histamine, localizing carboxypeptidase to mast cell secretory granules. The enzyme activity was also detected in preparations of dispersed human mast cells from skin and in extracts of whole skin. The inhibitor profile and m.w. of carboxypeptidase activity from preparations of dispersed mast cells from skin was similar to that from dispersed mast cells from lung. Mast cell carboxypeptidase had a m.w. on gel filtration of 30,000 to 35,000. The enzyme in crude lysates of dispersed mast cell preparations had optimal activity between pH 8.5 and 9.5 and was inhibited by potato inhibitor, which distinguished it from carboxypeptidase in cultured human foreskin keratinocytes and adult fibroblasts, and from other proteolytic mast cell enzymes. The enzyme activity was also inhibited by EDTA, o-phenanthroline, and, to a small extent, by 8-OH quinoline, but not by Captopril, soybean trypsin inhibitor, or pepstatin. These findings demonstrate that human mast cell secretory granules contain carboxypeptidase in addition to tryptase and chymase. It appears that mast cells from skin may have a higher content of carboxypeptidase than do mast cells from lung. 相似文献
20.
Summary The activated dimonophosphate of 3-deoxyadenosine (cordycepin) undergoes oligomerization to produce a new family of pyrophosphate-linked oligomers in which the average repeating unit involves a nine-atom structural group. The presence of a poly(U) template increase the relative yields of higher oligomers, although the template-free reaction is itself extremely efficient.For the previous paper in this series see Schwartz et al. (1987) 相似文献