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951.
不同浓度的NO^—3和NH^+4对小麦根谷氨酰胺合成酶及其相关酶的影响 总被引:15,自引:0,他引:15
利用酶活性测定和 Northern分子杂交等技术 ,研究了小麦幼苗根在不同浓度的 Na NO3 和(NH4) 2 SO4的供应下 ,其谷氨酰胺合成酶 (GS)、天冬酰胺合成酶 (AS)、谷氨酸脱氢酶 (GDH)、硝酸还原酶 (NR)以及 GS- m RNA的变化。结果表明 :NH 4 处理的小麦 ,其根部 GS活性比 NO-3 处理的高 ;高浓度处理的比低浓度处理的高 ;Northern杂交结果说明 GS- m RNA转录量与 GS活性一致 ;3mmol/ L NO-3促进了 AS的活性。AS酶活性变化与 GS酶活性变化无明显依赖关系。在实验的条件下 ,没能测出 GDH的活性 ,不同浓度的 NO-3 和 NH 4 处理对 NR活性没有明显的规律。 相似文献
952.
Ingrid Moeller Rebecca A. Lew Frederick A. O. Mendelsohn A. Ian Smith Michelle E. Brennan Timothy J. Tetaz Siew Yeen Chai 《Journal of neurochemistry》1997,68(6):2530-2537
Abstract: Angiotensin IV (Val-Tyr-Ile-His-Pro-Phe) has been reported to interact with specific high-affinity receptors to increase memory retrieval, enhance dopamine-induced stereotypy behavior, and induce c- fos expression in several brain nuclei. We have isolated a decapeptide (Leu-Val-Val-Tyr-Pro-Trp-Thr-Gln-Arg-Phe) from sheep brain that binds with high affinity to the angiotensin IV receptor. The peptide was isolated using 125 I-angiotensin IV binding to bovine adrenal membranes to assay receptor binding activity. This peptide is identical to the amino acid sequence 30–39 of sheep βA - and βB -globins and has previously been named LVV-hemorphin-7. Pharmacological studies demonstrated that LVV-hemorphin-7 and angiotensin IV were equipotent in competing for 125 I-angiotensin IV binding to sheep cerebellar membranes and displayed full cross-displacement. Using in vitro receptor autoradiography, 125 I-LVV-hemorphin-7 binding to sheep brain sections was identical to 125 I-angiotensin IV binding in its pattern of distribution and binding specificity. This study reveals the presence of a globin fragment in the sheep brain that exhibits a high affinity for, and displays an identical receptor distribution with, the angiotensin IV receptor. This globin fragment, LVV-hemorphin-7, may therefore represent an endogenous ligand for the angiotensin IV receptor in the CNS. 相似文献
953.
Many enteric pathogens are thought to enter a viable but nonculturable state when deprived of nutrients. Virulent strains of the enteric pathogen Vibrio parahaemolyticus are rarely isolated from their low-nutrient aquatic environments, possibly due to their nonculturability. Host factors such as bile may trigger release from dormancy and increase virulence in these strains. In this study, the addition of bile or the bile acid deoxycholic acid to estuarine water-cultured bacteria led to an increase in the direct viable count and colony counts among the virulent strains. This effect was not demonstrated in the nonvirulent strains, and it was reversed by extraction of bile acids with cholestyramine. Bile-treated V. parahaemolyticus had lower levels of intracellular calcium than untreated cells, and this effect coincided with an increase in the number of metabolically active cells. Chelation of intracellular calcium with BAPTA/AM (R. Y. Tsien, Biochemistry 19:2396-2402, 1980) produced similar results. Addition of bile to V. parahaemolyticus cultures in laboratory medium enhanced factors associated with virulence such as Congo red binding, bacterial capsule size, and adherence to epithelial cells. These results suggest that a bile acid-containing environment such as that found in the human host favors growth of virulent strains of V. parahaemolyticus and that bile acids enhance the expression of virulence factors. These effects seem to be mediated by a decrease in intracellular calcium. 相似文献
954.
It was identified that there were 4 St chromosomes derived from Th.intermedium in common wheat-Th.intermedium alien additional line TAI-27 by in situ hybridization.Two St chromosomes added to wheat chromosome in TAI-27 as well as two of them replaced two of 42 in wheat chromosomes.This indicates that TAI-27 is not only an alien additional line,but also a replacing line.The additional chromosomes in TAI-27 were microdissected and a microcloning library was constructed.A special probe of Th.intermedium was obtained from a microcloning library.The sequence analysis indicated that there were no homology with Genebank data.This makes it possible to screen genes with the disease-resistance,adversity-tolerance and fine character from Th.intermedium. 相似文献
955.
956.
运用分子力学方法研究了 2 0个双分子三螺旋DNA ,其嘧啶链序列是 5′- dTTCTTTTC- L1TTTL5 -CTTTTCTT -3′,划线的 5个核苷酸组成loop环 ,L1和L5可以是任意的核苷酸 ;嘌呤链的序列是 5′- GAAAAGAA 3′和 5′- AAGAAAAG -3′ ;2条链方向相反 .对 2 0个不同loop序列双分子三螺旋DNA稳定性的研究结果表明 ,5′- loop三螺旋比相应的 3′- loop三螺旋更稳定 ,嘌呤比嘧啶与相邻碱基的堆积作用大 .2 0个三螺旋DNA的相对稳定性主要是由loop环上L1和L5碱基组成不同决定的 相似文献
957.
在克隆人类遗传病致病基因的过程中,寻找染色体特定区段的转录序列成为主要的限速步骤.早期的努力集中在筛选cDNA文库,找寻进化上保守的DNA序列,以及Northern杂交.最近几年,在人类基因组计划的推动下,发展了数种有效的寻找基因的新方法.这些方法不但扩展了寻找新基因的染色体区段,而且能在不依赖基因表达的情况下进行筛选.文中综述新旧几种寻找基因的方法,并讨论它们各自的优点与局限. 相似文献
958.
Mohammad Ali Li-Yuan Chai Hai-Ying Wang Chong-Jian Tang Xiao-Bo Min Xu Yan Cong Peng Yu-Xia Song Ping Zheng 《Biodegradation》2016,27(2-3):131-144
The short-cut nitrification (SCN) performance of an airlift reactor (ALR) was investigated under increasing bicarbonate condition. The sequential increase of bicarbonate from 2.5 to 7.0 g/L accelerated the nitrite accumulation and improved the NAP to 99 %. With the increase of bicarbonate dose to 11 g/L, the ammonium removal efficiency and the ammonium removal rate (ARR) were improved to 95.1 % and 0.57 kg/m3/day, respectively. However, the elevation of bicarbonate concentration from 11.0 to 14.0 g/L gradually depreciated the nitrite accumulation percentage to 62.5 %. Then, the reactor was operated in increasing ammonium strategy to increase the nitrogen loading rate (NLR) to 1.1 kg/m3/day under 700 mg/L influent ammonium concentration. The ARR and nitrite production rate were elevated to 1.1 and 0.9 kg/m3/day, respectively. The SCN performance was improved to 1.8 kg/m3/day (NLR) by the subsequent progressive shortening of HRT to 4.8 h at ammonium concentration of 350 mg/L, which was 1.6 times higher than that of the increasing ammonium strategy. Chemical analysis with EDS, FTIR and XRD confirmed the presence of CaCO3 precipitates on biomass surface during the long-term operation under high bicarbonate conditions. The attachment of precipitates to the SCN sludge helped to improve the biomass settleability and finally enhanced the SCN performance of the ALR. 相似文献
959.
960.