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991.
Molla F. Mengist Dan Milbourne Sheila Alves Mike J. McLaughlin Peter W. Jones Denis Griffin 《Plant and Soil》2018,427(1-2):139-148
Aims
We investigated whether density fractionation can be used to determine the distribution of organic phosphorus (OP) between free and mineral-associated soil organic matter (SOM).Methods
We performed density fractionations using sodium polytungstate solution (specific gravity 1.6 g cm?3) on 20 soils from UK semi-natural and pasture ecosystems, to obtain a light fraction (LF) and a heavy fraction (HF) for each soil. The fractions were quantified by weight, and analysed for organic carbon (OC), total N (TN), total P (TP), inorganic P (IP), and OP (by difference).Results
Good recoveries of soil mass (96%), OC and TN (both ~ 90%) were obtained, but recovery of OP only averaged 56%. The average P:C ratio of HF SOM exceeded that of LF SOM by a factor of six, greater than the factor of two obtained for TN:OC. For the soils studied, the elements of SOM were predominantly in the HF, with averages of 75% for C, 82% for N, and 90% for P.Conclusions
The incomplete recovery of OP demands further work. Nonetheless, the results show that HF SOM is much richer in P than LF SOM.992.
Selective base excision repair of DNA damage by the non‐base‐flipping DNA glycosylase AlkC 下载免费PDF全文
Rongxin Shi Elwood A Mullins Xing‐Xing Shen Kori T Lay Philip K Yuen Sheila S David Antonis Rokas Brandt F Eichman 《The EMBO journal》2018,37(1):63-74
DNA glycosylases preserve genome integrity and define the specificity of the base excision repair pathway for discreet, detrimental modifications, and thus, the mechanisms by which glycosylases locate DNA damage are of particular interest. Bacterial AlkC and AlkD are specific for cationic alkylated nucleobases and have a distinctive HEAT‐like repeat (HLR) fold. AlkD uses a unique non‐base‐flipping mechanism that enables excision of bulky lesions more commonly associated with nucleotide excision repair. In contrast, AlkC has a much narrower specificity for small lesions, principally N3‐methyladenine (3mA). Here, we describe how AlkC selects for and excises 3mA using a non‐base‐flipping strategy distinct from that of AlkD. A crystal structure resembling a catalytic intermediate complex shows how AlkC uses unique HLR and immunoglobulin‐like domains to induce a sharp kink in the DNA, exposing the damaged nucleobase to active site residues that project into the DNA. This active site can accommodate and excise N3‐methylcytosine (3mC) and N1‐methyladenine (1mA), which are also repaired by AlkB‐catalyzed oxidative demethylation, providing a potential alternative mechanism for repair of these lesions in bacteria. 相似文献
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995.
Elevation of body temperature by 2–3°C induces a 2.7 kilobase hsp70 mRNA species in the rabbit retina within 1 hr. In situ hybridization with thin sections derived from plastic-embedded tissue permitted a higher level of resolution of retinal cell types compared to procedures which involved the use of frozen tissue sections. A prominent induction of hsp70 mRNA in retinal ganglion cells was observed when an hsp70 riboprobe was utilized for in situ hybridization. These results indicate that this neuronal cell type responds rapidly to fever-like body temperatures by inducing one of the major heat shock genes. 相似文献
996.
John R Bradley David B Evans Sheila M Gore Alan J Cowley 《BMJ (Clinical research ed.)》1988,296(6637):1634-1637
The role of peripheral vascular tone in the development of hypotension induced by dialysis was investigated in eight patients undergoing haemodialysis with acetate or bicarbonate buffered fluid. Each patient had two sessions of dialysis with acetate fluid and two with bicarbonate fluid in the order acetate, bicarbonate, bicarbonate, acetate or bicarbonate, acetate, acetate, bicarbonate. Mean arterial blood pressure fell at a mean rate of 3·9 mm Hg/hour during dialysis with acetate fluid and 1·4 mm Hg/hour during dialysis with bicarbonate fluid. The rate of fall was significantly greater during dialysis with acetate fluid compared with bicarbonate fluid. Heart rate increased by a mean rate of 2·6 beats/min/hour during dialysis with both acetate and bicarbonate fluid. Vascular resistance in the forearm increased at a rate of 3·6 units/hour during dialysis with acetate fluid and 4·5 units/hour during dialysis with bicarbonate fluid, but the venous bed of the forearm dilated. The index of venous tone rose at a mean rate of 0·23 ml/100 dl over 40 mm Hg/hour during dialysis with acetate fluid and 0·20 ml/dl over 40 mm Hg/hour during dialysis with bicarbonate fluid.Inappropriate peripheral venodilatation may be important in the development of hypotension induced by dialysis. 相似文献
997.
N. C. Bhattacharya P. P. Ghosh Sheila Bhattacharya D. R Hileman P. K. Biswas 《Biologia Plantarum》1988,30(3):204-209
Ten centimeter long stem cuttings of sweet potato (Ipomoea batatas L. cv. Georgia Jet) with intact apex and leaves were cultured in distilled water as well as in varying concentrations of
abscisic acid (ABA) in open top chambers at 364, 438 and 666 cm3 m{-3}CO2. Low concentration of ABA promoted rooting and elongation of roots at 364 cm3 m{-3} CO2 while rooting was suppressed at enriched levels of CO2. However, biomass production in shoots and roots was higher in 666 than in 364 cm3 m-3 CO2. 相似文献
998.
Frank J. Penedo Betina Yanez Sheila F. Casta?eda Linda Gallo Katy Wortman Natalia Gouskova Melissa Simon William Arguelles Maria Llabre Lisa Sanchez-Johnsen Carrie Brintz Patricia Gonzalez Linda Van Horn Alfred W. Rademaker Amelie G. Ramirez 《PloS one》2016,11(1)
Cancer has surpassed heart disease as the leading cause of death among Hispanics in the U.S., yet data on cancer prevalence and risk factors in Hispanics in regard to ancestry remain scarce. This study sought to describe (a) the prevalence of cancer among Hispanics from four major U.S. metropolitan areas, (b) cancer prevalence across Hispanic ancestry, and (c) identify correlates of self-reported cancer prevalence. Participants were 16,415 individuals from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), who self-identified as Cuban, Dominican, Mexican, Puerto Rican, Central or South American. All data were collected at a single time point during the HCHS/SOL baseline clinic visit. The overall self-reported prevalence rate of cancer for the population was 4%. The rates varied by Hispanic ancestry group, with individuals of Cuban and Puerto Rican ancestry reporting the highest cancer prevalence. For the entire population, older age (OR = 1.47, p < .001, 95% CI, 1.26–1.71) and having health insurance (OR = 1.93, p < .001, 95% CI, 1.42–2.62) were all significantly associated with greater prevalence, whereas male sex was associated with lower prevalence (OR = 0.56, p < .01, 95% CI, .40-.79). Associations between study covariates and cancer prevalence also varied by Hispanic ancestry. Findings underscore the importance of sociodemographic factors and health insurance in relation to cancer prevalence for Hispanics and highlight variations in cancer prevalence across Hispanic ancestry groups. Characterizing differences in cancer prevalence rates and their correlates is critical to the development and implementation of effective prevention strategies across distinct Hispanic ancestry groups. 相似文献
999.
The Ssr protein (T1E_1405) from Pseudomonas putida DOT‐T1E enables oligonucleotide‐based recombineering in platform strain P. putida EM42 下载免费PDF全文
Tomás Aparicio Sheila I. Jensen Alex T. Nielsen Victor de Lorenzo Esteban Martínez‐García 《Biotechnology journal》2016,11(10):1309-1319
Some strains of the soil bacterium Pseudomonas putida have become in recent years platforms of choice for hosting biotransformations of industrial interest. Despite availability of many genetic tools for this microorganism, genomic editing of the cell factory P. putida EM42 (a derivative of reference strain KT2440) is still a time‐consuming endeavor. In this work we have investigated the in vivo activity of the Ssr protein encoded by the open reading frame T1E_1405 from Pseudomonas putida DOT‐T1E, a plausible functional homologue of the β protein of the Red recombination system of λ phage of Escherichia coli. A test based on the phenotypes of pyrF mutants of P. putida (the yeast's URA3 ortholog) was developed for quantifying the ability of Ssr to promote invasion of the genomic DNA replication fork by synthetic oligonucleotides. The efficiency of the process was measured by monitoring the inheritance of the changes entered into pyrF by oligonucleotides bearing mutated sequences. Ssr fostered short and long genomic deletions/insertions at considerable frequencies as well as single‐base swaps not affected by mismatch repair. These results not only demonstrate the feasibility of recombineering in P. putida, but they also enable a suite of multiplexed genomic manipulations in this biotechnologically important bacterium. 相似文献
1000.
Silvana Gomes Benzecry Márcia Almeida Alexandre Sheila Vítor-Silva Jorge Luis Salinas Gisely Cardoso de Melo Helyde Albuquerque Marinho ?ngela Tavares Paes André Machado de Siqueira Wuelton Marcelo Monteiro Marcus Vinícius Guimar?es Lacerda Heitor Pons Leite 《PloS one》2016,11(3)