全文获取类型
收费全文 | 2146篇 |
免费 | 54篇 |
国内免费 | 77篇 |
出版年
2022年 | 21篇 |
2021年 | 37篇 |
2020年 | 21篇 |
2019年 | 35篇 |
2018年 | 50篇 |
2017年 | 31篇 |
2016年 | 42篇 |
2015年 | 40篇 |
2014年 | 80篇 |
2013年 | 101篇 |
2012年 | 114篇 |
2011年 | 149篇 |
2010年 | 120篇 |
2009年 | 80篇 |
2008年 | 81篇 |
2007年 | 98篇 |
2006年 | 90篇 |
2005年 | 74篇 |
2004年 | 75篇 |
2003年 | 62篇 |
2002年 | 90篇 |
2001年 | 93篇 |
2000年 | 71篇 |
1999年 | 41篇 |
1998年 | 20篇 |
1997年 | 10篇 |
1994年 | 11篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 29篇 |
1989年 | 28篇 |
1988年 | 29篇 |
1987年 | 31篇 |
1986年 | 26篇 |
1985年 | 29篇 |
1984年 | 27篇 |
1983年 | 22篇 |
1979年 | 15篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 22篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1972年 | 17篇 |
1971年 | 17篇 |
1970年 | 15篇 |
1968年 | 18篇 |
1967年 | 13篇 |
1966年 | 11篇 |
1965年 | 9篇 |
排序方式: 共有2277条查询结果,搜索用时 78 毫秒
101.
102.
A new subspecies of entomopathogenic nematode, Steinernema feltiae protense subsp. n., isolated from Yakutia grasslands is described. These nematodes demonstrate a high invasion activity to insect-hosts at 6 degrees C, maximum infestation of insect-hosts was registered at 13-21 degrees C. 相似文献
103.
Budantsev AIu Iarkov AIu Ivanova IuV 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1999,49(6):962-970
Physostigmine (0.7-0.8 mg/kg, i.p.) decreased and pentobarbital (13.4-14.6 mg/kg) increased the locomotor and emotional activity of rats in the "open field". Both drugs induced the reversible amnesia to a conditioned reaction in a double T-maze with positive (nutritional) reinforcement. These changes in behavioral activity were correlated with dissociated learning of rats after the injection of the drugs: physostigmine largely decreased the number of errors during learning as compared with pentobarbital. However, in both cases rats reached the learning criterion sooner than the control animals due to the shorter reaction latency (physostigmine) and increase in general motor activity (pentobarbital). 相似文献
104.
105.
The immobilisation efficiency of the complexes of oligonucleotide/poly(L-lysine) on two polymeric carboxy-rich surfaces, i.e. poly(styrene/maleic acid) (PSMA) and poly(styrene/maleic anhydride) (PSMAA), has been investigated using X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and fluorescence-based measurements of DNA attachment. A molecularly thin layer of either electrostatically or covalently (via amide bond) bound poly(L-lysine) allows the 'switching' from COOH-based to NH(2)-based surface functionality. The results indicate that approximately 54-57% and 55-62% of the applied oligonucleotides bind to polymeric surfaces via the route of electrostatic adsorption of poly(L-lysine) and covalent bonding of poly(L-lysine), respectively. This system can be applied conveniently for the detection of nucleic acids in both disposable and reusable biosensors. 相似文献
106.
Entomopathogenic nematodes are widely used as biological insecticides for agricultural and horticultural pests. In the vast majority of cases, commercial products contain nematodes partially dehydrated on to inert solid carriers. Nematode survival in these products is generally poor, they are difficult to handle and are not suitable for use with all nematode species. We have developed a non-viscous, non-adhesive and non-toxic liquid formulation for nematode storage and transport based on neutral density colloidal silica suspensions. Survival and virulence of nematodes stored in this formulation without aeration was superior to nematodes stored in aerated quarter strength Ringer's solution. 相似文献
107.
Vasil'eva SV Abramova TV Ivanova TM Shishkin GV Silnikov V N 《Bioorganicheskaia khimiia》2004,30(3):264-272
A convenient preparative synthesis of 2'-amino-2'-deoxyuridine was developed. Starting from 2'-amino-2'-deoxyuridine and 2'-amino-2'-deoxycytidine, monomers for the phosphoamidite oligonucleotide synthesis were obtained that carry a linker with methoxyoxalamide groups in position 2'. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 3; see also http://www.maik.ru. 相似文献
108.
109.
Mironova NL Boutorine YI Pyshnyi DV Ivanova EM Zenkova MA Vlassov VV 《Nucleosides, nucleotides & nucleic acids》2004,23(6-7):885-890
RNA cleaving conjugates have been prepared by attachment of oligodeoxyribonucleotide TTTT to peptides containing arginine, leucine, proline and serine residues. The highest activity was displayed by the conjugates containing peptides with alternating arginine and leucine residues (LR)4G-amide. Ribonuclease activity of the conjugates pep-T4 decreases in the order T4-(LR)4G > T4-(LR)2G > T4-(LLRR)2G > T4-(LR)2PRLRG > S2R3-Hmda-T4 > or = R5 double dagger (LR)3. According to CD spectra, the free peptide (LR)4G-amide in water solution at neutral pH and physiological ionic strength has no pronounced secondary structure whereas conjugated to oligonucleotide it acquires a folding similar to alpha-helix. 相似文献
110.
Shishimorova M. S. Ivanova L. B. Ryabykh V. P. 《Russian Journal of Developmental Biology》2004,35(5):316-318
We studied the influence of combined microinjection of a gene engineering construct and site-specific endonuclease SalIin the pronucleus on preimplantation development of (CBA × C57BL)F1 mouse embryos in vitro. The rate of survival of the embryos was estimated according to their capacity to develop until the blastocyst stage and hatch from zona pellucida. The results obtained suggest that the microinjection of exogenous DNA jointly with endonuclease SalI at concentrations from 0.1 to 0.01 U/l decreased reliably the rate of survival, as compared to the control (p < 0.05 and p < 0.01, respectively). However, a decrease of endonuclease SalI concentration in the injection mixture to 0.01 U/l enhanced the capacity of mouse embryos to develop until the blastocyst stage and hatch from zona pellucida, as compared to the embryos microinjected with exogenous DNA and endonuclease SalI at a higher concentration. 相似文献