全文获取类型
收费全文 | 4895篇 |
免费 | 337篇 |
国内免费 | 1篇 |
出版年
2021年 | 39篇 |
2020年 | 25篇 |
2019年 | 36篇 |
2018年 | 50篇 |
2017年 | 47篇 |
2016年 | 83篇 |
2015年 | 104篇 |
2014年 | 118篇 |
2013年 | 326篇 |
2012年 | 221篇 |
2011年 | 252篇 |
2010年 | 144篇 |
2009年 | 149篇 |
2008年 | 229篇 |
2007年 | 215篇 |
2006年 | 245篇 |
2005年 | 184篇 |
2004年 | 249篇 |
2003年 | 245篇 |
2002年 | 211篇 |
2001年 | 133篇 |
2000年 | 135篇 |
1999年 | 115篇 |
1998年 | 72篇 |
1997年 | 58篇 |
1996年 | 62篇 |
1995年 | 54篇 |
1994年 | 43篇 |
1993年 | 42篇 |
1992年 | 112篇 |
1991年 | 107篇 |
1990年 | 91篇 |
1989年 | 97篇 |
1988年 | 95篇 |
1987年 | 67篇 |
1986年 | 54篇 |
1985年 | 56篇 |
1984年 | 55篇 |
1983年 | 43篇 |
1982年 | 55篇 |
1981年 | 47篇 |
1980年 | 35篇 |
1979年 | 64篇 |
1978年 | 38篇 |
1977年 | 40篇 |
1976年 | 25篇 |
1975年 | 35篇 |
1974年 | 36篇 |
1973年 | 27篇 |
1972年 | 25篇 |
排序方式: 共有5233条查询结果,搜索用时 62 毫秒
101.
In Vitro Bleaching of Hardwood Kraft Pulp by Extracellular Enzymes Excreted from White Rot Fungi in a Cultivation System Using a Membrane Filter 总被引:6,自引:4,他引:2
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
To clarify the role of excreted extracellular enzymes during long-term incubation in a pulp biobleaching system with white rot fungi, we developed a cultivation system in which a membrane filter is used; this membrane filter can prevent direct contact between hyphae and kraft pulp, but allows extracellular enzymes to attack the kraft pulp. Phanerochaete sordida YK-624 brightened the pulp 21.4 points to 54.0% brightness after a 5-day in vitro treatment; this value was significantly higher than the values obtained with Phanerochaete chrysosporium and Coriolus versicolor after a 7-day treatment. Our results indicate that cell-free, membrane-filtered components from the in vitro bleaching system are capable of delignifying unbleached kraft pulp. Obvious candidates for filterable reagents capable of delignifying and bleaching kraft pulp are peroxidase and phenoloxidase proteins. The level of secreted manganese peroxidase activity in the filterable components was substantial during strain YK-624 in vitro bleaching. A positive correlation between the level of manganese peroxidase and brightening of the pulp was observed. 相似文献
102.
Antioxidant Properties of Bromocriptine, a Dopamine Agonist 总被引:3,自引:1,他引:2
Toshikazu Yoshikawa† Yukiko Minamiyama Yuji Naito Motoharu Kondo 《Journal of neurochemistry》1994,62(3):1034-1038
Abstract: It has been suggested that free radicals may adversely influence the pathogenesis of Parkinson's disease. We conducted this study to determine whether bro-mocriptine, an agent widely used for treating parkinsonism, possesses antioxidant effects. Bromocriptine scavenged superoxide produced from a superoxide generating system (hypoxanthine-xanthine oxidase) by the spin-trapping method using electron spin resonance. Bromocriptine had a strong scavenging effect on the 5,5-dimethyl-1-pyrroline- N -oxide hydroxide signal produced from Fenton's reaction. Bromocriptine also attenuated the stable free radical diphenyl- p -picrylhydrazyl signal. This drug inhibited the autooxidation of rat brain homogenates in a dose-dependent manner in vitro. Autooxidation of brain homogenates collected from rats treated with bromocriptine (2.5 mg/kg, i.p., daily for 3 days) was significantly reduced as compared with values in untreated rat homogenates. These observations suggest that bromocriptine is a free radical scavenger and a potent antioxidant. 相似文献
103.
Soh Chang-Ho; Kamiya Yuji; Yoshida Shigeo; Yamane Hisakazu; Takahashi Nobutaka 《Plant & cell physiology》1994,35(7):1037-1042
Oryzains, cysteine proteinases of rice seeds, are induced byGA3 in germinating rice seeds [Abe et al. (1987) Agric. Biol.Chem. 51: 1509]. The effects of GA1, GA3, GA4, GA9, and GA20on the production of oryzain and -amylase were investigatedin embryoless half- and whole-seeds of rice (cv. Nipponbare).When gibberellins (GAs) were incubated with embryoless half-seeds,GA1, GA3 and GA4 induced oryzain and -amylase, but GA9, andGA20 did not. GA9 and GAM induced oryzain and -amylase productionin whole seeds, but this production was inhibited by the simultaneousapplication of prohexadione, an inhibitor of 2ß- and3ß-hydroxylation of GAs. Prohexadione did not inhibitthe activities of oryzain and -amylase induced by GA1. Theseresults suggest that GAs possessing the 3ß-hydroxylgroup induce activities of oryzain and -amylase in rice seedsand that GA9 and GA20 have activity only after they are convertedmetabolically to active GAs, probably GA4 and GA1, respectively.GA1, was more active than GA4 in both half seeds and wholeseeds incubation. Oryzain and -amylase activities induced byGA4 were significantly inhibited in the presence of 104M prohexadione. This suggests that the conversion of GA1, toGA4 (13-hydroxylation) might be inhibited at a high dose ofprohexadione in whole seeds.
4Present address: Institute of Food Development, Kyung Hee University,Suwon 449-701, Korea 相似文献
104.
Kazuhito Hisatsune Takehiro Iguchi Yuji Haishima Norihiko Tamura Seiichi Kondo 《Microbiology and immunology》1993,37(2):143-147
The chemical properties of a lipopolysaccharide (LPS) isolated from a new O-antigenic form (O13) of Vibrio parahaemolyticus were investigated. The LPS contained glucose, galactose, L -glycero-D -manno-heptose and glucosamine. 2-Keto-3-deoxy-octonate (KDO) was not detected in the LPS by the periodate-thiobarbituric acid test (Weissbach's reaction) under conventional hydrolysis conditions. Instead, phosphorylated KDO (X1 and X2) was found in its strong-acid hydrolysate. This sugar composition was identical to that of V. parahaemolyticus O3, O5 and O11 LPS, indicating that, based on the sugar composition, O13 LPS belongs to Chemotype III to which O3, O5 and O11 belong. In addition, structural study demonstrated the presence of KDO 4-phosphate in its inner-core region. 相似文献
105.
To understand force generation under a wide range of loads, the stepping of single kinesin molecules was measured at loads from −20 to 42 pN by optical tweezers with high temporal resolution. The optical trap has been improved to halve positional noise and increase bandwidth by using 200-nm beads. The step size of the forward and backward steps was 8.2 nm even over a wide range of loads. Histograms of the dwell times of backward steps and detachment fit well to two independent exponential equations with fast (~0.4 ms) and slow (>3 ms) time constants, indicating the existence of a fast step in addition to the conventional slow step. The dwell times of the fast steps were almost independent of the load and ATP concentration, while those of the slow backward steps and detachment depended on those. We constructed the kinetic model to explain the fast and slow steps under a wide range of loads. 相似文献
106.
Koiwai Keiichiro Kondo Hidehiro Hirono Ikuo 《Marine biotechnology (New York, N.Y.)》2023,25(3):488-502
Marine Biotechnology - The classification of cells in non-model organisms has lagged behind the classification of cells in model organisms that have established cluster of differentiation marker... 相似文献
107.
M. Kondo W. E. Finkbeiner J. H. Widdicombe 《In vitro cellular & developmental biology. Animal》1993,29(1):19-24
Summary Tracheal epithelial cells were grown on Nuclepore filters coated with human placental collagen. When grown immersed in medium
containing fetal bovine serum, cells displayed an undifferentiated ultrastructure (no cilia and a cell height of ∼ 10 μm).
Short-circuit current (Isc) was approximately 1/10 that of the native epithelium. By contrast, when grown in hormonally defined, serum-free medium with
an air interface, cells showed Isc equal to or greater than the original tissue, possessed cilia, and had a cell height of ∼ 50 μm. Responses in Isc to mediators were similar to those of the original tissue, but differed from those of dog or human tracheal epithelium. Given
the ready availability and low cost of the native tissues, bovine tracheal cultures grown in serum-free medium with an air
interface should prove useful in studies of airway epithelial physiology. 相似文献
108.
Jo Kitawaki Shigeo Inoue Takaya Tamura Takara Yamamoto Hideo Honjo Tadayoshi Higashiyama Yoshio Osawa Hiroji Okada 《The Journal of steroid biochemistry and molecular biology》1993,45(6):485-491
To clarify whether cigarette smoking during pregnancy causes an organic alteration in placental estrogen producing ability, we determined the catalytic activity of aromatase by the tritiated water assay, and tissue level of aromatase cytochrome P-450 (P-450arom) by the specific enzyme-linked immunosorbent assay, in placental samples from nonsmokers and smokers. As pregnancy progressed, both aromatase activity and P-450arom concentration increased in placentas from nonsmokers and smokers. However, the gradient of the increase was significantly less in heavy smokers (20 cigarettes a day) than in normal and moderate smokers (<20 cigarettes a day). At term, the mean aromatase activity and P-450arom concentration in placentas from heavy smokers were significantly lower than in nonsmokers and moderate smokers, while aromatase activity per P-450arom (turnover rate) and the mean placental weight were comparable among the three groups. In contrast, the ratio of aryl hydrocarbon hydroxylase activity to aromatase activity was higher in placentas from heavy smokers. Immunohistochemical studies showed that P-450arom was localized in the cytoplasm of syncytiotrophoblasts of chorionic villi in placentas from both nonsmokers and smokers. These results suggest that the induction of placental P-450arom during gestation is suppressed by maternal smoking, resulting in a reduction in estrogen producing ability, while placental xenobiotic P-450 is induced. 相似文献
109.
Kyosuke Mushiake Fumiaki Motoyoshi Naomi Kondo Hiroyuki Shimizu Tadao Orii 《Biotherapy》1993,7(2):101-107
Five patients with common variable immunodeficiency treated in our hospital between December 1979 and December 1990 were given six kinds of intravenous immunoglobulin preparations (pepsin treated, S-sulfonated, polyethylene glycol treated, pH4 treated, alkylated, and pH4.25 formulation preparation) for replacement therapy. Duration of the therapy ranged from 7.6 to 11 years. Incidences of fever and acute infections were variable among patients, but no significant differences were seen in the incidences among periods given each preparation. Three cases revealed abnormal pulmonary functions in tests. Adverse reactions were rarely seen in our study periods, and no severe reactions were observed. No significant differences were seen in incidences of adverse reactions. Postinfusion levels of serum complement slightly decreased from preinfusion levels. However, the decrease in complement was not related to any adverse reaction. No long-term complications such as transmission of hepatitis have been observed. Our data suggest that no obvious differences exist between the efficacy and safety of each IVIG preparation. Differences of efficacy of IVIG replacement therapy may be due to the variable pathophysiology of each patient.Abbreviations CVID
common variable immunodeficiency
- IVIG
intravenous immunoglobulin 相似文献
110.