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61.
迷宫漏斗蛛Agelena labyrinthica的染色体(蜘蛛目:漏斗蛛科) 总被引:2,自引:0,他引:2
报告迷宫漏斗蛛的染色体数目、形态结构和性染色体组成。结果表明,迷宫漏斗蛛体细胞染色体数目是:雄性2n=42,雌性2n=44,性别决定机制属X_1X_2O型。X染色体是全部染色体中最长的和最短的2个(对)。染色体似乎均为端或亚端着丝粒染色体,这由C-显带标本分析所证实,没有亚中着丝粒染色体的证据。C-带标本分析表明,常染色体中,各条染色体的C-带纹,其大小和染色深浅无明显差异,但X_2染色体上有明显宽的C-带纹。C-显带处理没有得到稳定的有重复性的带纹。 相似文献
62.
朱砂叶螨羧酸脂酶最优测试条件的选择 总被引:1,自引:0,他引:1
应用二次回归通用旋转组合设计,对朱砂叶螨离体羧酸酯酶测试过程中所需缓冲液pH值、恒温时间、反应温度及底物浓度,设立4因子5水平试验,在考虑4个因子主效应和互作效应的情况下,筛选测试羧酸酯酶的最优条件组合。 相似文献
63.
从人良性增生前列腺组织中经硫酸铵沉淀和肝素-琼脂糖凝胶层析纯化出人前列腺生长因子(hPGF),纯化倍数约1000倍,SDS-PAGE和等电聚焦电泳示分子量约为17kD、等电点同标准bFGF,利用分离培养的人前列腺间质成纤维细胞进行活性鉴定,发现以1.3~1.7mol/LNaCl洗脱部分为hPGF,活性最高,对间质成纤维细胞有显著刺激增殖作用。 相似文献
64.
Magnesium Adenosine 5[prime]-Triphosphate-Energized Transport of Glutathione-S-Conjugates by Plant Vacuolar Membrane Vesicles 总被引:5,自引:3,他引:2 下载免费PDF全文
By characterization of the uptake of glutathione-S-conjugates, principally dinitrophenyl-S-glutathione (DNP-GS), by vacuolar membrane vesicles, we demonstrate that a subset of energy-dependent transport processes in plants are not H+-coupled but instead are directly energized by MgATP. The most salient features of this transport pathway are: (a) its specific, obligate requirement for MgATP as energy source; (b) the necessity for hydrolysis of the [gamma]-phosphate of MgATP for uptake; (c) the insensitivity of uptake to uncouplers of the transtonoplast H+ gradient (carbonylcyanide 4-trifluoromethoxyphenylhydrazone, gramicidin-D, and NH4Cl); (d) its pronounced sensitivity to vanadate and partial inhibition by vinblastine and verapamil; (e) the lack of chemical modification of DNP-GS either during or after transport; (f) the capacity of S-conjugates of chloroacetanilide herbicides, such as metolachlor-GS, but not free herbicide, to inhibit uptake; and (g) the ability of vacuolar membrane vesicles purified from a broad range of plant species, including Arabidopsis, Beta, Vigna, and Zea, to mediate MgATP-dependent, H+-electrochemical potential difference-independent DNP-GS uptake. On the basis of these findings it is proposed that the transport of DNP-GS across the vacuolar membrane of plant cells is catalyzed by a glutathione-conjugate transporter that directly employs MgATP rather than the energy contained in the transtonoplast H+-electrochemical potential difference to drive uptake. The broad distribution of the vacuolar DNP-GS transporter and its inhibition by metolachlor-GS are consistent with the notion that it plays a general role in the vacuolar sequestration of glutathione-conjugable cytotoxic agents. 相似文献
65.
A series of compounds (DAP-AA) composed of an amino acid (AA) and a dialkyl phosphoryl group (DAP) is the basic elements of life chemistry. Self-catalysis of DAP-AA gives the self-assembly oligopeptides, even in aqueous medium at 38°C. The oligo-nucleotides could also be assembled from nucleosides' phosphorylation by DAP-AA. DAP-AA acts as the energy source as well as the phosphoryl donor for the synthesis of nuclic Acids and protein. A general expression for the self assembly system is proposed. 相似文献
66.
J. F. M. L. Seegers W. J. J. Meijer G. Venema S. Bron A. C. Zhao S. A. Khan 《Molecular & general genetics : MGG》1995,249(1):43-50
The single-strand origin (SSO) of the rolling-circle (RC), broad-host-range lactococcal plasmid pWVO1 was functionally characterized. The activity of this SSO in the conversion of single-stranded DNA to double-stranded DNA was tested both in vivo and in vitro. In addition, the effect of this SSO on plasmid maintenance was determined. The functional pWVO1 SSO comprises a 250 by region, containing two inverted repeats (IRs). The activity of each IR was tested, separately and in combination, in a plasmid derivative that was otherwise completely devoid of structures that might function as SSO. One of the IRs (IR 1) showed some homology with other previously described SSOs of the SSOA type, as well as with the conversion signal of the Escherichia coli phage X174. This IR was shown to have a partial, RNA polymerise-independent activity in complementary strand synthesis, both in vivo and in vitro. The second IR, which had no activity of its own, was required for full SSO activity, both in vivo and in vitro. The conversion of single-stranded DNA to the double-stranded form by the complete SSO was only partly sensitive to inhibition by rifampicin, indicating the existence of an RNA polymerase-independent pathway for this event. The results suggest that the pWVO1 SSO can be activated by two different routes: an RNA polymerise-dependent one (requiring the entire SSO), and an RNA polymerase-independent one (requiring only IR I). 相似文献
67.
Jinyuan Liu Chikage Hara Masaaki Umeda Yuan Zhao Thomas W. Okita Hirofumi Uchimiya 《Plant molecular biology》1995,29(4):685-689
Using a cDNA library prepared from poly(A)+ RNA from 10-day-old rice endosperm, partial nucleotide sequences of randomly isolated clones were analyzed. A total of 153 (30.6%) out of 500 cDNA clones showed high amino acid identity to previously identified genes. There was significant redundancy in cDNAs encoding prolamine and glutelin. About 21.0% of the cDNA clones were found to code for seed storage protein genes. Consequently, 37 independent genes were identified. Using cDNA clones encoding glutelin, prolamine, seed allergen, -1,4-glucan branching enzyme, glycine-rich RNA binding protein, metallothionein, non-specific lipid-transfer protein and ubiquitin conjugating enzyme the accumulation of mRNA during rice seed development was compared. Genes associated with seed storage protein and starch biosynthesis were expressed according to expected developmental stages. Glycinerich RNA binding protein genes as well as metallothionein-like protein genes were highly expressed in developing seeds, but low in leaves of whole plants. 相似文献
68.
Zhao Yan-Xiu Philip J. C. Harris Yao Dun-Yi 《Plant Cell, Tissue and Organ Culture》1995,40(2):119-123
Protoplasts were isolated from cotyledons of Sesbania bispinosa (Jacq.) W.F. Wight. In a liquid-over-agar culture system with Murashige and Skoog (MS) medium supplemented with 1 mg l-1 2,4-dichlorophenoxyacetic acid (2,4-d, 2 mg l-1 benzyladenine (BA), 1 mg l-1 glutamine and 0.5 and formed callus. The first division occurred after 3–4 days. Callus formed from the protoplasts differentiated shoots by organogenesis on MS medium with 1 mg l-1 indolebutyric acid (IBA) and 1 mg l-1 BA. These shoots developed into complete plantlets when excised and cultured on MS medium with 0.5 mg l-1 IBA. 相似文献
69.
Proteus mirabilis amino acid deaminase: cloning, nucleotide sequence, and characterization of aad. 总被引:2,自引:0,他引:2 下载免费PDF全文
Proteus, Providencia, and Morganella species produce deaminases that generate alpha-keto acids from amino acids. The alpha-keto acid products are detected by the formation of colored iron complexes, raising the possibility that the enzyme functions to secure iron for these species, which do not produce traditional siderophores. A gene encoding an amino acid deaminase of uropathogenic Proteus mirabilis was identified by screening a genomic library hosted in Escherichia coli DH5 alpha for amino acid deaminase activity. The deaminase gene, localized on a cosmid clone by subcloning and Tn5::751 mutagenesis, was subjected to nucleotide sequencing. A single open reading frame, designated aad (amino acid deaminase), which appears to be both necessary and sufficient for deaminase activity, predicts a 473-amino-acid polypeptide (51,151 Da) encoded within an area mapped by transposon mutagenesis. The predicted amino acid sequence of Aad did not share significant amino acid sequence similarity with any other polypeptide in the PIR or SwissProt database. Amino acid deaminase activity in both P. mirabilis and E. coli transformed with aad-encoding plasmids was not affected by medium iron concentration or expression of genes in multicopy in fur, cya, or crp E. coli backgrounds. Enzyme expression was negatively affected by growth with glucose or glycerol as the sole carbon source but was not consistent with catabolite repression. 相似文献
70.
Sequence requirements for the termination of rolling-circle replication of plasmid pT181 总被引:3,自引:0,他引:3
Most small multicopy plasmids of Gram-positive bacteria and many in Gram-negative bacteria replicate by a rolling-circle (RC) mechanism. The replication initiator proteins encoded by the RC plasmids and single-stranded bacteriophages of Escherichia coli have origin-specific nicking-closing activities that are required for the initiation and termination of RC replication. We have investigated the sequence requirements for termination of RC replication of plasmid pT181. The initiator nick site is located in the loop of a hairpin region (IRII) within the pT181 origin of replication. By mutational analysis, we have found that several nucleotides within the stem of IRII which are critical for the initiation activity are dispensable for termination of replication. We also demonstrate that nucleotides in the right arm of IRII, but not the left arm, are absolutely required for termination of RC replication. We have also identified specific nucleotides in IRII that are critical for its termination activity. The sequence of the right arm of the hairpin must be located downstream of the initiator nick site for termination, suggesting that termination requires a specific orientation of the initiator protein at the origin. 相似文献