全文获取类型
收费全文 | 716篇 |
免费 | 21篇 |
专业分类
737篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 20篇 |
2014年 | 29篇 |
2013年 | 42篇 |
2012年 | 33篇 |
2011年 | 40篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 36篇 |
2007年 | 32篇 |
2006年 | 38篇 |
2005年 | 42篇 |
2004年 | 53篇 |
2003年 | 48篇 |
2002年 | 44篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 19篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1967年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有737条查询结果,搜索用时 15 毫秒
1.
Anaerobic biodegradability of polyvinyl alcohol 总被引:4,自引:0,他引:4
Summary Biodegradability of polyvinyl alcohol (PVA) under anaerobic conditions was demonstrated using anaerobic river sediments and anaerobically treated activated sludge from a sewage treatment plant. PVA having molecular weights of 2000 and 14000 was over 60% biodegraded as determined by TOC. 相似文献
2.
Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats An immunohistochemical study 总被引:1,自引:0,他引:1
Dr. Shinji Tamura Sumio Kawata Mitsuhiro Okamoto Seiichiro Tarui 《Cell and tissue research》1988,252(2):397-401
Summary Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa. 相似文献
3.
Mamoru Tsukuda Izumi Mochimatsu Miki Sakumoto Yasukazu Mikami Seiichiro Yuyama Shunsuke Yanoma 《Biotherapy》1993,6(3):167-174
Interleukin-7 (IL-7) has an ability to stimulate the proliferation of pre-B cells. It has been shown that IL-7 can also activate T lymphocytes. We here demonstrate that IL-7 in combination with interleukin-2 (IL-2) can drive cell proliferation and enhance the autologous tumor cell lysis by peripheral blood mononuclear cells (PBMC) and autologous mixed lymphocyte tumor cell culture (MLTC)-derived effector cells (MLTC cells). These synergistic effects of IL-2 and IL-7 on the proliferation and the augmentation of autologous tumor cell lysis were found for both effector cells. These effects were inhibited by neutralizing antibodies to IL-2 or IL-7, and by a combination of both antibodies, significantly. In terms of phenotypical expression, CD3 positive cells comprised the vast majority of MLTC cells after culture in medium containing IL-2 and IL-7 with an increase of IL-2 receptor positive cells.Abbreviations CD
cluster differentiation
- IFN
interferon
- IL
interleukin
- JRU
Japanese Reference Unit
- LAK
lymphokine activated killer
- mAb
monoclonal antibody
- MLTC
mixed lymphocyte tumor cell culture
- PBMC
peripheral blood mononuclear cells
- TILs
tumor infiltrating lymphocytes 相似文献
4.
The association of absorbed aluminium (Al) with nuclei in Alaskapea roots was shown by zonal centrifugation of isolated nuclei.In nuclei, 73% of the total incorporated Al was detected inthe DNP fraction. Furthermore, Al in DNP was found to be boundspecifically to DNA by gel filtration of dissociated DNP. (Received March 19, 1977; ) 相似文献
5.
To investigate the biological effects of exposure to feeble high frequency electromagnetism, skin surface temperature, blood vessel (arterioles and venules) diameter were examined, using infrared thermography, a laser doppler flowmeter, and a video microscope, respectively, in the ear of rabbits. After exposing the ear of rabbits to high frequency electromagnetism value of 9 MHz for 15 minutes, continued rising of local temperature was demonstrated. Though dilatation of arterioles was not seen. In addition, venules tended to dilate and blood flow also to increase, and microcirculation was accelerated at the site where electromagnetism was exposed. Hazardous effects of long term exposures of high frequency electromagnetism (9 MHz for 30 days, 8 hours/day) on guinea pigs were not observed in their behavior, food consumption, body and organ weights, hematological and biochemical values, macroscopic and microscopic findings on autopsy. 相似文献
6.
T Suzuki K Tamai Y Kodama A O Asita A Matsuoka T Sofuni M Kurita H Ohtsuki T Hiwatashi M Hayashi 《Mutation research》1992,278(2-3):169-173
Micronucleus assays using mouse peripheral blood stained vitally on acridine orange (AO)-coated slides were evaluated at two laboratories with 7,12-dimethylbenz[a]anthracene (DMBA) and compared with the standard bone marrow assay. DMBA was administered by single intraperitoneal injection to CD-1 mice at doses ranging from 5 to 80 mg/kg, then 5 microliters of peripheral blood was sampled from a tail vein at 24, 48, 72, 96, and 120 h after treatment. Similar incidences of micronucleated young erythrocytes were observed in peripheral blood reticulocytes and bone marrow polychromatic erythrocytes. The dose response of micronucleated reticulocytes was delayed compared to that of micronucleated polychromatic erythrocytes. The dose-response curves after treatment with DMBA differed depending on the sampling times, which revealed the difficulty of obtaining accurate dose-response relations in the micronucleus assay. The present result demonstrated that the simple and rapid AO supravital staining method is a valuable and easier method for obtaining dose- and time-response data for quantification of micronucleus induction by chemicals. 相似文献
7.
Lettuce hypocotyl elongation caused by gibberellic acid wasstrongly inhibited by coumarin and dichlobenil, known inhibitorsof cellulose biosyndiesis. Stress-relaxation analysis of thecell wall revealed that gibberellic acid induces a decreasein both minimum relaxation time (To) and relaxation rate (b)and an increase in maximum relaxation time (Tm), when gibberellicacid stimulates hypocotyl elongation. Both coumarin and dichlobenilnullified the effect of gibberellic acid on changes in To, Tmand b values. The content of pectic, hemicellulosic and cellulosic substancesin the cell wall increased per hypocotyl but decreased per unithypocotyl length, in response to gibberellic acid treatment.Particularly, gibberellic acid caused a substantial increasein cellulose content per hypocotyl but a decrease per unit length.A good correlation existed between the decrease in To and thedecrease in hemicellulose content per unit lengdi of the cellwall. The increase in Tm was correlated with the decrease incellulose content per unit length of the cell wall. The decreasein b was correlated with the decrease in the content of bothcellulose and hemicellulose per unit length. Based on these results, we discuss the role of polysaccharidemetabolism of the cell wall in gibberellic acid-induced lettucehypocotyl elongation and the nature of gibberellic acid-inducedbiochemical modifications of the cell wall, which are representedby changes in stress-relaxation properties of the cell wall.
1Present address: Department of Anatomy, Aichi Medical University,Nagakutecho, Aichigun, Aichi 480-11, Japan. (Received September 22, 1975; ) 相似文献
8.
The mechanism by which dihydroconiferyl alcohol (DCA) stimulatesindole-3-acetic acid (IAA)-induced elongation of cucumber hypocotylsections was studied. Although DCA did not affect the uptakeof IAA-5-3H by hypocotyl sections, the endogenous level of IAA-5-3Hin DCA-treated sections was much higher than in DCA untreatedones. IAA-5-3H in the incubation medium was degraded in thepresence of hypocotyl sections, and this degradation of IAAwas inhibited by DCA. An in vitro experiment with horseradishperoxidase revealed that DCA inhibited the IAA degrading activityof the oxidase, as did caffeic acid and ferulic acid. Theseresults suggested that DCA enhances IAA-induced cucumber hypocotylelongation by acting as an antioxidant of IAA. (Received June 4, 1975; ) 相似文献
9.
Susumu Miyata Yonezo Suzuki Seiichiro Kamisaka Yoshio Masuda 《Physiologia plantarum》1981,51(4):402-406
Indole-3-acetaldehyde oxidase was partially purified from the epicotyl of Pisum satiyum seedlings by column chromatography using CM-Sephadex and Sephadex G-150. The enzyme was only active in the presence of molecular oxygen. The activity was maximal at pH 8.0, and the Km value for indole-3-acetaldehyde was 1.4 × 10−3 M . The enzyme was inhibited strongly by p -hydroxymercuribenzoate, cyanide and hydroxylamine, suggesting that it contains sulfhydryl group(s) and a metal component such as iron. 相似文献
10.
Björkbom A Róg T Kankaanpää P Lindroos D Kaszuba K Kurita M Yamaguchi S Yamamoto T Jaikishan S Paavolainen L Päivärinne J Nyholm TK Katsumura S Vattulainen I Slotte JP 《Biochimica et biophysica acta》2011,1808(4):1179-1186
We have prepared palmitoyl sphingomyelin (PSM) analogs in which either the 2-NH was methylated to NMe, the 3-OH was methylated to OMe, or both were methylated simultaneously. The aim of the study was to determine how such modifications in the membrane interfacial region of the molecules affected interlipid interactions in bilayer membranes. Measuring DPH anisotropy in vesicle membranes prepared from the SM analogs, we observed that methylation decreased gel-phase stability and increased fluid phase disorder, when compared to PSM. Methylation of the 2-NH had the largest effect on gel-phase instability (T(m) was lowered by ~7°C). Atomistic molecular dynamics simulations showed that fluid phase bilayers with methylated SM analogs were more expanded but thinner compared to PSM bilayers. It was further revealed that 3-OH methylation dramatically attenuated hydrogen bonding also via the amide nitrogen, whereas 2-NH methylation did not similarly affect hydrogen bonding via the 3-OH. The interactions of sterols with the methylated SM analogs were markedly affected. 3-OH methylation almost completely eliminated the capacity of the SM analog to form sterol-enriched ordered domains, whereas the 2-NH methylated SM analog formed sterol-enriched domains but these were less thermostable (and thus less ordered) than the domains formed by PSM. Cholestatrienol affinity to bilayers containing methylated SM analogs was also markedly reduced as compared to its affinity for bilayers containing PSM. Molecular dynamics simulations revealed further that cholesterol's bilayer location was deeper in PSM bilayers as compared to the location in bilayers made from methylated SM analogs. This study shows that the interfacial properties of SMs are very important for interlipid interactions and the formation of laterally ordered domains in complex bilayers. 相似文献