全文获取类型
收费全文 | 2305篇 |
免费 | 159篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 42篇 |
2020年 | 27篇 |
2019年 | 39篇 |
2018年 | 41篇 |
2017年 | 40篇 |
2016年 | 71篇 |
2015年 | 97篇 |
2014年 | 102篇 |
2013年 | 148篇 |
2012年 | 163篇 |
2011年 | 174篇 |
2010年 | 106篇 |
2009年 | 85篇 |
2008年 | 127篇 |
2007年 | 133篇 |
2006年 | 132篇 |
2005年 | 126篇 |
2004年 | 119篇 |
2003年 | 118篇 |
2002年 | 115篇 |
2001年 | 22篇 |
2000年 | 32篇 |
1999年 | 26篇 |
1998年 | 21篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 21篇 |
1991年 | 31篇 |
1990年 | 19篇 |
1989年 | 16篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1981年 | 8篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 13篇 |
1971年 | 9篇 |
1970年 | 8篇 |
1968年 | 6篇 |
排序方式: 共有2464条查询结果,搜索用时 140 毫秒
1.
Maria V. Sergeeva Vadim V. Mozhaev Joseph O. Rich Yuri L. Khmelnitsky 《Biotechnology letters》2000,22(17):1419-1422
A novel biocatalytic reaction of transamidation of non-activated amides with amines is reported. Among 45 different lipolytic and proteolytic enzymes tested, only the lipase from Candida antarcticawas able to catalyze this reaction. The reaction proceeded with up to ca. 80% conversion in anhydrous methyl tert-butyl ether and worked with both N-substituted and unsubstituted amides. The biocatalytic transamidation is an equilibrium process and, therefore, higher conversions to the desired amide were achieved by using increased concentrations of the amine nucleophile. 相似文献
2.
Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time. 相似文献
3.
P V Sergeev A S Dukhanin A V Seme?kin 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(12):678-681
In has been shown that cortisol immobilized on polyvinylpyrrolidone (PVP-GC) affects cyclic AMP production stimulated by adenosine and isoproterenol in rat thymocytes. This effect of PVP-GC is specific for cortisol: antiglucocorticoid progesterone (at a concentration of 10(-5) M) inhibited completely the action of PVP-GC on the intracellular cAMP level. It is suggested that cortisol effect on cAMP production is one of the mechanisms of glucocorticoid hormone action in target cells. 相似文献
4.
N A Medvedeva T C Vo I Iu Sergeev I M Rodionov 《Biulleten' eksperimental'no? biologii i meditsiny》1987,103(5):517-520
Neuromediated behaviour of feline caudal femoral arteries was studied in vitro. Transmural stimulation of arteries, previously constricted by noradrenaline, caused an up to 58% relaxation of the induced tone. Atropine (10(-5) g/ml) blocked this response by 93%. The removal of endothelium did not affect the magnitude of the response. It is suggested that the caudal femoral artery is an example of a blood vessel which has muscarinic receptors located directly on its smooth muscles. 相似文献
5.
A. Yu. Tsibulevsky T. K. Dubovaya A. I. Shchegolev A. I. Sergeev A. V. Bykov Kh. K. Gadzhieva 《Biology Bulletin》2005,32(6):590-596
Intoxication with bacterial lipopolysaccharide (endotoxin) is accompanied by considerable rearrangements in the systems of blood microcirculation and water metabolism of the liver. These rearrangements are manifested as increased sinusoid area, changed total area of the cytoplasm and nuclei as well as the nucleocytoplasmic ratio in hepatocytes, increased content of total water in the organ, and changed magnetic relaxation properties (spin-lattice and spin-spin relaxation times). Preliminary parasympathetic denervation of the liver (vagotomy) changes the pattern of the organ response to bacterial endotoxin poisoning as indicated by the kinetics of studied morphological and biophysical parameters. 相似文献
6.
N G Kalina S I Elkina V V Sergeev 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1984,(12):107-110
The stimulating influence of glucose-containing muramyldipeptide (GMDP) on the nonspecific resistance of mice was shown to depend on the features of the pathogenesis of the infection. Thus, the intraperitoneal injection of GMDP increased the survival rate of mice infected with Escherichia coli, but had no stimulating effect on the resistance of the animals to Salmonella typhimurium natural infection in whose pathogenesis macrophages played an essential role. Experiments demonstrated that GMDP was capable of enhancing the ingestive function of macrophages, but did not increase their bactericidal activity with respect to this infection. 相似文献
7.
A A Sergeev Iu G Chernukha K L Shakhanina Z A Gol'denshte?n E Ia Potashnikova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1989,(7):66-71
The possibility of using the enzyme-linked immunosorbent assay (ELISA) for the diagnosis of leptospirosis has been shown. This method has proved to be more simple and sensitive than the leptospiral microagglutination and lysis test. The data on obtaining genus-specific leptospiral antigens are presented. As revealed in this study, the antigens obtained by the complex treatment of microbial cells with ultrasound and detergents show the maximum activity in ELISA. The optimum parameters of the ELISA system for the diagnosis of leptospirosis have been established. 相似文献
8.
Daphniopsis australis, a new species of cladoceran in Australian salt lakes, is described, and some brief comments on its distribution are given. 相似文献
9.
Yoko Yamauchi Hikari Kimoto Xianyu Yang Sergey Filkin Yuri Utkin Tai Kubo 《Bioscience, biotechnology, and biochemistry》2016,80(1):158-161
Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α2βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity. 相似文献
10.
Examination of 933 schoolchildren in the Kyurdamir district of Azerbaijan for the carriage of abnormal variants of serum cholinesterase (EC 3.1.1.8.) revealed high biochemical polymorphism of the enzyme. This was conditioned by high frequencies of mutant alleles of the E1-E1a and E1s loci responsible for atypical and "silent" enzyme variants. The cases of confusions of phenotypes of different heterozygotes are being analyzed using the material on pedigrees. Two types of the normal alleles (E1u)--E1u1 and E1u2--were shown to be present in the population analyzed. 相似文献