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981.
Robert B. Kirkpatrick Zahida Parveen Presley F. Martin 《Genesis (New York, N.Y. : 2000)》1994,15(2):188-200
A transient expression assay has been used to investigate the cause of a tissuespecific position effect on Adh expression from a transgene insertion in Drosophila. A 15.4-kb genomic clone containing the 3.2-kb Adh insert along with flanking regions of genomic DNA is expressed in this assay in a tissue-specific pattern resembling the abnormal expression pattern of the position effect. The 3.2-kb Adh insert is expressed normally without the flanking sequences. A silencer element is located upstream of the Adh gene within a 2-kb fragment that acts in both orientations and at a distance of at least 6.5 kb from the larval Adh promoter to suppress ADH expression in a nontissue specific fashion. The DNA sequence of the 2-kb fragment indicates that it is a noncoding region. A 17-bp sequence is repeated within this region and may be associated with the silencer activity, since subclones from the 2-kb fragment, each containing one of the repeated regions, both retain full silencer activity. This silencer fails to suppress expression from an α1-tubulin promoter-LacZ fusion construct or an hsp70 promoter-Ach fusion construct. In addition to the silencer, another element is located downstream of the Adh gene that produces a higher level of anterior than posterior midgut expression. These results suggest that the 5′ silencer and the 3′ element act together to create the tissue specific pcsition effect characteristic of the GC-1 line. © 1994 Wiley-Liss, Inc. 相似文献
982.
Brian F. Thomas A. Robert Jeffcoat Mary W. Myers James M. Mathews C. Edgar Cook 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1994,655(2)
A method is described for the simultaneous determination of l-α-acetylmethadol (LAAM) and its N-demethylated metabolites, l-α-noracetylmethadol (norLAAM) and l-α-dinoracetylmethadol (dinorLAAM), in plasma by gas chromatography—chemical ionization mass spectrometry. Deuterated internal standards for each analyte serve as carriers and control for recovery during sample purification on a solid-phase extraction column (C18), and subsequent separation and analysis on a DB-17 capillary column. With this method, we have determined levels of LAAM, norLAAM, and dinorLAAM in small volumes of plasma (100 μl). The limit of quantitation for all analytes was approximately 1.0 ng/g plasma and the limit of detection was approximately 0.5 ng/g plasma. An experimental application is also described where these analytes are quantitated in plasma obtained from rats before, during, and after chronic administration of LAAM-HCl. Since this technique affords a selective and sensitive means of detection of LAAM and its active, N-demethylated metabolites in small samples of blood, it may enable patient compliance to be more easily assessed by allowing samples to be collected by a simple finger-prick technique. 相似文献
983.
William D. Figg Herman J.C. Yeh Alain Thibault James M. Pluda Fumio Itoh Robert Yarchoan Michael R. Cooper 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1994,652(2)
This paper describes a reversed-phase, high-performance liquid chromatographic (HPLC) method for the isolation, detection, and quantification of TNP-470 (I) and one of its active metabolites, AGM-1883 (II), from plasma. These compounds are initially extracted from plasma with an organic solvent and then separated from one another on a C18 column. Those fractions eluting from the C18 column and containing either I or II are then derivatized through their epoxide moieties with sodium 8-quinolinethiolate (SQT). This derivatization produces fluorescent species that are isolated and quantified by a second reversed-phase HPLC analysis. The assay yields a lower limit of reliable quantification of 2.5 ng/ml and is linear to a concentration at least as high as 160 ng/ml. The inter-assay percent coefficient of variation is less than 18%. 相似文献
984.
985.
986.
Hiro Mori Robert E. Palmer Paul W. Sternberg 《Molecular genetics and genomics : MGG》1994,245(6):781-786
We have identified a Caenorhabditis elegans homolog of p34cdc2 kinase. The C. elegans homolog, ncc-1, is ~-60% identical to p34cdc2 of Homo sapiens. When expressed from a constitutive yeast promoter, ncc-1 is capable of complementing a conditional lethal mutation in the CDC28 gene of Saccharomyces cerevisiae, indicating that this C. elegans homolog can properly regulate the cell cycle. 相似文献
987.
Karen A. Kernper Roger G. Sargent J. Wanzer Drane Robert E Valois James R. Hussey 《Obesity (Silver Spring, Md.)》1994,2(2):117-126
Different cultural norms and standards for appropriate female body size might contribute to the disparity in obesity rates between black and white adult females (46.0% and 24.6% respectively). The purpose of this study was to measure adolescents' perceptions of ideal size and social norms regarding female body size as well as adolescents' perceptions of significant others' evaluation and expectations of the adolescents' body size. Subjects included 437 adolescent girls (247 white and 190 black) aged 13 to 19 (x=44.9, SD=.979) from six randomly selected public schools. The subjects, heights and weights were measured. Responses to a body image questionnaire and a series of nine female body drawings (arranged ordinally, 1 to 9, from thinnest to heaviest) were analyzed using the General Linear Model and Logistic Regression. The female body size considered ideal by black females was significantly larger than the size selected as ideal by white females (x= 3.47 and x= 3.13 respectively, p< 0.001). Black females were two times more likely than white females to describe themselves as thinner than other girls their age (O.R. = 2.01, 95% C.I.1.34, 3.01) and seven times as likely to say that they were not overweight (O.R. = 7.08, 95% C.I. 3.72, 13.45). White females wanted to be a smaller size than they currently were and felt encouraged by significant others to lose weight or reduce their size. Black females did not indicate as great a desire as whites to be smaller and they tended to feel that their size was considered satisfactory by significant others. Only subjects from the low SES group perceived that significant others wanted them to gain weight. The differences between black and white subjects' beliefs and perceptions about body size norms may explain, in part, why heavier body weights persist in some cultural groups. 相似文献
988.
While the majority of sympathetic neurons are noradrenergic, a minority population are cholinergic. At least one population of cholinergic sympathetic neurons arises during development by a target-dependent conversion from an initial noradrenergic phenotype. Evidence for retrograde specification has been obtained from transplantation studies in which sympathetic neurons that normally express a noradrenergic phenotype throughout life were induced to innervate sweat glands, a target normally innervated by cholinergic sympathetic neurons. This was accomplished by transplanting footpad skin containing sweat gland primordia from early postnatal donor rats to the hairy skin region of host rats. The sympathetic neurons innervating the novel target decreased their expression of noradrenergif traints and developed choline acetyltransferase (ChAT) activity. In addition, many sweat gland-associated fibers acquired acetylcholinesterase (AChE) staining and VIP immunoreactivity. These studies indicated that sympathetic neurons in vivo alter their neurotransmitter phenotype in response to novel envronmental signals and that sweat glands play a critical role in the cholinergic and peptidergic differentiation of the sympathetic neurons that innervate them. The sweat gland-derived cholinergic differentiation factor is distinct from leukemia inhibitory factor and ciliary neurotrophic factor, two well-characterized cytokines that alter the neurotransmitter properties of cultured sympathetic neurons in a similar fashion. Recent studies indicate that anterograde signalling is also important for the establishment of functional synapses in this system. We have found that the production of cholinergic differentiation activity by sweat glands required sympathetic innervation, and the acquisition and maintenance of secretory competence by sweat glands depends upon functional cholinergic innervation. 1994 John Wiley & Sons, Inc. 相似文献
989.
Colonies of honeybees (Apis mellifera L.) were established thatvaried in the proportions of their workers that were of Europeanand hybrid (Africanized x European) descent. Colony defensiveresponses increased with higher proportions of hybrid workers.Colonies consisting exclusively of hybrid workers did not differin their response from "pure" Africanized colonies, suggestingthat the strong defensive behavior of Africanized workers isgenetically dominant. European workers became more defensivein colonies that also contained hybrid workers, whereas hybridworkers became less defensive in the same mixed colonies. Inmixed colonies hybrid workers were individually more likelythan Europeans to sting a leather target but not more likelyto guard the entrance. 相似文献
990.
Zhijian Li Robert L. Jarret Roy N. Pittman James W. Demski 《In vitro cellular & developmental biology. Plant》1994,30(4):187-191
Summary Thidiazuron (TDZ) was utilized to induce adventitious shoot formation from the hypocotyl region of cultured seed explants
of peanut (Arachis hypogaea L.). Excision of the radicle from seed explants was more stimulatory to shoot initiation than removal of the epicotyl alone.
Removal of both the radicle and the epicotyl from seeds resulted in a 37-fold increase in the frequency of shoot production
when compared to intact seeds. Half seed explants with epicotyl and radicle removed produced the greatest number of shoots
per explant. Explants from mature seeds were more responsive to TDZ than immature seed-derived explants. A 1-wk exposure to
10 μM TDZ was sufficient to stimulate the initiation of adventitious shoots that subsequently developed into plants. High frequency
of shoot initiation was readily induced in a variety of genotypes ofA. hypogaea and a wild peanut (A. glabrata). Plants regenerated from shoots induced by TDZ were phenotypically normal and fertile. 相似文献