全文获取类型
收费全文 | 3262篇 |
免费 | 188篇 |
国内免费 | 1篇 |
出版年
2021年 | 35篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 59篇 |
2015年 | 102篇 |
2014年 | 133篇 |
2013年 | 163篇 |
2012年 | 172篇 |
2011年 | 177篇 |
2010年 | 106篇 |
2009年 | 127篇 |
2008年 | 196篇 |
2007年 | 169篇 |
2006年 | 166篇 |
2005年 | 200篇 |
2004年 | 180篇 |
2003年 | 151篇 |
2002年 | 157篇 |
2001年 | 107篇 |
2000年 | 94篇 |
1999年 | 80篇 |
1998年 | 31篇 |
1997年 | 41篇 |
1996年 | 28篇 |
1995年 | 28篇 |
1994年 | 36篇 |
1993年 | 30篇 |
1992年 | 51篇 |
1991年 | 51篇 |
1990年 | 38篇 |
1989年 | 46篇 |
1988年 | 36篇 |
1987年 | 34篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 28篇 |
1981年 | 19篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1975年 | 13篇 |
1974年 | 22篇 |
1973年 | 10篇 |
1971年 | 11篇 |
1969年 | 10篇 |
1968年 | 14篇 |
1965年 | 9篇 |
排序方式: 共有3451条查询结果,搜索用时 78 毫秒
31.
Akiko Tomaru Ryota Sasaki Hidekazu Miyahara Akitoshi Okino Nobuhiro Ogawa Koji Hamasaki 《PloS one》2014,9(1)
It has been reported that planula larvae of some jellyfish prefer artificial substrates for settlement. This research focused on the relationship between the settlement of planulae and the wettability of artificial substrate surfaces. We used atmospheric plasmas to change the wettability of the surfaces of polycarbonate (PC) plates because plasma treatment has no chemical side effects. The treatment made the surfaces hydrophilic, as evidenced by the decrease of contact angle from 85° to 35°. X-ray photoelectron spectroscopy revealed that the change of wettability of the PC plates could be attributed to N2, which was probably ionized in the air above the plates. Scanning electron microscopy revealed no difference in the surface morphology of the plates before and after plasma treatment. Results of bioassays using treated PC plates showed that planulae tended to preferentially settle on hydrophobic surfaces. 相似文献
32.
33.
34.
A method for quantitative expression of the hardness of agar plate medium was studied. As the method for expressing the hardness by using real values of the load which an agar plate medium could sustain for a certain length of time was found to be inaccurate, we proposed a method to express the hardness by utilizing the frequency with which various loads were sustained for a given period of time and the obtained value is referred to as 'gel solidity' (GS). The GS value within a certain range was found to be statistically useful because it linearly reflected the changes in variables in experimental conditions in respect to agar, such as agar concentration, thickness of the agar layer and the temperature of the environment, and especially because it can provide a quantitative as well as reproducible value for the hardness of agar plate medium. On the other hand, GS was little, if at all, affected by variables unrelated to agar. 相似文献
35.
F Furuyama Y Ishida M Furuyama T Hashitani Y Isobe H Sato K Ohara H Nishino 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1989,94(1):133-138
1. The relationship between thermal salivation (TS) and thermoregulation was studied in anesthetized rats. 2. Of the 6 anesthetics used, ketamine-anesthetized rats secreted the largest amount of saliva. Salivation, however, was thermal and not induced by ketamine itself. 3. Ketamine-anesthetized rats readily secreted saliva at core temperatures less than 40 degrees C but TS was remarkably enhanced by hyperthermia of 40-42.5 degrees C. 4. The equilibrium phase in the triphasic heat response of core temperature was a consequence of equilibrium between heat gain and heat loss by salivation. 相似文献
36.
Kunisuke Nagamatsu Yasumasa Kido Tadao Terao Takashi Ishida Satoshi Toki 《Life sciences》1982,30(13):1121-1127
The ability of sulfhydryl compounds to provide protection against the acute toxicity of morphinone was investigated in mice. Subcutaneous administration of morphinone produced a reduction of hepatic non-protein sulfhydryl concentration. Pretreatments of mice with glutathione or cysteine significantly increased the survival rate of mice given a lethal dose of morphinone, whereas morphinone lethality was markedly potentiated by diethyl maleate. On the other hand, the administration of morphine produced a dose dependent reduction of hepatic non-protein sulfhydryl contents. However, neither glutathione nor cysteine protected mice from the acute toxicity of morphine. A possible explanation for these observations was proposed as follows: morphine is oxidized by morphine 6-dehydrogenase to morphinone, and the morphinone thus produced decreases the sulfhydryl contents in the liver. This mechanism is supported by the fact that morphinone reacts easily with glutathione and cysteine . 相似文献
37.
T Ishida K Yamamoto T Shotake K Nozawa M Hayami Y Hinuma 《Microbiology and immunology》1986,30(4):315-321
African non-human primates were surveyed seroepidemiologically for natural infection of human T-cell leukemia virus type I (ATLV/HTLV-I) or its closely related virus(es). Materials from three genera (Cercopithecus, Papio, and Theropithecus), four species (grivet monkey, Anubis baboon, Hamadryas baboon, and gelada), totalling 983 animals under natural conditions, were obtained in a field study in Ethiopia. Virus infection was determined by the indirect immunofluorescence test using HTLV-I specific antigens. Animals seropositive for HTLV-I were found among grivet monkeys and Anubis baboons including the hybrid offspring between Anubis and Hamadryas baboons but not pure-Hamadryas baboons and geladas. From these results, the HTLV-I family was proved to be widespread on the African continent and was regarded as a common retrovirus among catarrhines. 相似文献
38.
A rapid identification method of glucose nonfermentative gram-negative rods was established and 320 strains isolated were divided into five groups according to their characteristics in pigmentation, acid from glucose, cytochrome oxidase activity and motility. Further characterization of the strains in each group resulted in the identification that the strains in group I were Pseudomonas aeruginosa, strains in group II, P. aeruginosa and Pseudomonas putida. Achromogenic strains of P. aeruginosa were classified into group III, Pseudomonas maltophilia, Pseudomonas alcaligenes and Alcaligenes faecalis into group IV and Acinetobacter calcoaceticus (Acinetobacter anitratus and Achromobacter lwoffii) in group V. When fluorescent pigment production was taken as a standard, 259 out of 263 chromogenic strains were identified as P. aeruginosa and the remaining four were P. putida. Whereas forty-five achromogenic strains included twenty-four A. calcoaceticus, eight P. aeruginosa, six A. faecalis, five P. maltophilia and two P. alcaligenes. From May 1970 to June 1971, 368 strains of glucose nonfermentative rods were isolated from clinical specimens sent to the Central Laboratories of Tohoku University Hospital and three fourth (286/368) of the isolates were P. aeruginosa 相似文献
39.
Cleavage of the C-Co bond of sterically hindered alkylcobalamins bearing neither an adenine moiety nor functional groups, such as isobutylcobalamin, neopentylcobalamin, and cyclohexylcobalamin, was markedly accelerated by their interaction with apoprotein of diol dehydrase, although these cobalamins do not function as coenzyme. Acceleration of the conversion of alkylcobalamins to enzyme-bound hydroxocobalamin was stoichiometric and obeyed first-order reaction kinetics. These results, together with strong competitive inhibition by these alkylcobalamins with respect to adenosylcobalamin, indicate that acceleration of the C-Co bond cleavage by the apoenzyme is due to labilization of their C-Co bond by binding to the active site of the enzyme. This labilization is considered to be caused by a steric distortion of the corrin ring which is induced by specific tight interaction of the cobalamin moiety with apoprotein. The importance of such a labilizing effect for activation of the C-Co bond of adenosylcobalamin in enzymatic reactions is discussed. 相似文献
40.
T Yamaguchi Y Kuroda M Saito T Ebina F Hoshino N Ishida 《Microbiology and immunology》1984,28(5):601-610
In mouse spleen cell cultures, TH69, a live Streptococcus faecalis (ATCC 31663) preparation, at a concentration of 20 micrograms/ml induced immune interferon (IFN gamma) with molecular weight ranging from 20,000 to 40,000 daltons together with a small amount of IFN alpha/beta. By using nonsensitized mouse spleen cells, the fact that both T-cells and macrophages are required for this IFN production was established. When these spleen cells were obtained from mice sensitized 12 days earlier with 4 mg of TH69, twice as much IFN was produced than in cells obtained from nonsensitized mice. This increase was explained by the presence of both sensitized macrophages and T-cells in a reconstitution experiment. 相似文献