全文获取类型
收费全文 | 204篇 |
免费 | 13篇 |
国内免费 | 3篇 |
专业分类
220篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 2篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 4篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
Summary The cytochemical localization of ATPase activity has been investigated in maize root cells using both lead and cerium-based capture methods. With both methods, staining at the plasma membrane was observed in all cells of the root, although the precipitate obtained with cerium was more uniform and granular than that with lead. Controls using no substrate or no magnesium, -glycerophosphate to replace ATP, vanadate or boiled tissue generally showed little or no staining. However, biochemical studies on purified plasma membrane fractions showed that ATPase activity was markedly inhibited by fixation, particularly by glutaraldehyde, and also by lead and cerium ions. Non-enzymic hydrolysis of ATP by cerium was greater than that by lead. The value and limitations of these procedures for the localization of plasma membrane H+-ATPase activity are summarized in relation to previous criticisms of these methods.Abbreviations DTT
dithiothreitol
- EDTA
ethylene diaminetetraacetic acid
- GP
B-glycerophosphate
- PCMBS
p-chloromercuribenzene sulphonic acid
- PMSF
phenylmethylsulphonyl fluoride 相似文献
2.
As fresh human cadaveric spine specimens for in vitro testing are hard to obtain and carry a potential risk of infection, the possibility of using embalmed spine specimens has been considered. The cross-linking effect of formalin fixation, however, raises uncertainties regarding the biomechanical likeness of preserved specimens. They have been reported to be stiffer, but no quantitative data exist.
The purpose of this study was to determine the biomechanical differences between fresh and formalin-fixed spine specimens, using L1–2 motion segments from six 16-week-old calf spines. The range of motion and neutral zone were determined in flexion-/extension, left/right axial rotation, and right/left lateral bending.
The range of motion decreased in the formalin fixed specimens by as much as 80%, and the neutral zone by as much as 96%. The results of this study therefore imply that, for biomechanical testing, formalin-fixed specimens are not representative of the in vivo conditions. 相似文献
3.
Andrea Casasco Marco Casasco Antonia Lcaro Cornaglia Marco Danova Monica Giordano Alberto Calligaro 《Biotechnic & histochemistry》1994,69(2):112-117
PC10 is a monoclonal antibody to proliferating cell nuclear antigen, a nuclear protein associated with the cell cycle. We have evaluated the effects of tissue fixation on PC10 immunoreactivity in sections of paraffin embedded rat tissues. Immunoreactivity was well preserved in tissues after fixation with alcohol-based solutions for 3-24 hr. Fewer PC10-positive cells were detectable in samples fixed with formaldehydecontaining solutions compared with samples fixed with alcohol for the same time. Loss of PC10 immunoreactivity in formaldehyde fixed tissues was progressive, and quantifiable as early as after 3 hr fixation. Consequently, alcohol-based fixatives are strongly recommended for any immunocytochemical prospective study using PC10 antibody. In contrast, loss of PC10-immunoreactivity is always predictable, but difficult to quantitate, using formaldehyde fixed specimens. This aspect should be considered when using PC10 antibody in retrospective studies with routinely-processed archival material. 相似文献
4.
VIP is present in the genitourinary system of man and animals. In man the highest concentrations are found in the penis, the uterus and vagina and in the urinary bladder. VIP nerves heavily innervate the erectile tissue of the male external genitalia, the uterine smooth muscle and blood vessels, the seromucous glands of the cervix, and the lamina propria and vaginal epithelium. In the urinary bladder, VIP nerves are located beneath the transitional epithelium, in the lamina propria and in the smooth muscle. Other areas well innervated by VIP nerves include the prostate, seminal vesicles and vasa deferentia. Chemical (phenol- and 6-OHDA) or surgical (hypogastric or pelvic nerve section) extrinsic denervation fail to deplete the genitourinary system of its VIP content, supporting the view that VIP-containing nerves originate from local ganglion cells. Indeed, neuronal cell bodies containing VIP are seen in the paracervical ganglia of the female genitalia, the para- or intramural bladder ganglia and scattered through the base of the cavernosum body, the neck of the bladder and the prostate. The finding of elevated levels of VIP in the local circulation after induced penile erection in man and mammals and the ability of VIP to relax the detrusor muscle of the bladder suggests that the peptide may be involved in penile erection and bladder relaxation, as does the marked VIP depletion in the penis or bladder in patients suffering from diabetic impotence or bladder instability. 相似文献
5.
Nitrogen-fixingAnabaena cylindrica cells are found to evolve hydrogen in high quantities in the presence of CO plus C2H2. Studies with the inhibitors dichlorophenyldimethylurea (DCMU), disalicylidenepropanediamine (DSPD), dibromothymoquinone (DBMIB), undecylbenzimidazole (UDB) and chloro-carbonyl-cyanide-phenylhydrazone (CCCP) and also withAnabaena grown on nitrate- and ammonia-nitrogen show that the H2-formation is due to the ATP-dependent H3O+-reduction catalysed by nitrogenase. In control experiments CO plus C2H2 inhibited the activities of a cell-free hydrogenase fromClostridium pasteurianum. It is concluded that Anabaena has a hydrogenase whose natural function is to recycle the H2 lost by the action of nitrogenase.Abbreviations Cl-CCP
m-chloro-carbonyl-cyanide-phenylhydrazone
- DSPD
disalicylidenepropanediamine(1–3)
- DBMIB
dibromothymoquinone
- DCMU
N-(3,4-dichlorophenyl) NN-dimethyl-urea
- UDB
2-undecyl-benzimidazole 相似文献
6.
M. I. Bajwa 《Plant and Soil》1981,62(2):299-303
Summary X-ray diffraction studies were made on soils with and without potassium fertility problems. All soils with clay fractions
containing dominant beidellite or vermiculite showed potassium deficiency and lack of response to potassium fertilizer applications.
All of the soils containing dominant montmorillonite or other clay minerals contained adequate potassium; on none of these,
poor potassium response was reported. Special management practices are needed on the beidellitic and vermiculitic soils to
increase potassium and ammonium fertilizer efficiency. Dominance of beidellite in the clay fraction should be reflected in
soil classification. Establishment of a ‘beidellite’ family differentiating criterion in the Soil Taxonomy is proposed for
this purpose. 相似文献
7.
Jacqueline Jollés FranÇOise Schoentgen Pierre Jollès Ellen M. Prager Allan C. Wilson 《Journal of molecular evolution》1976,8(1):59-78
Summary The amino acid sequence of lysozyme c from chachalaca egg white was determined. Like other bird lysozymes c, that of the chachalaca has 129 amino acid residues. It differs from other avian lysozymes c by 27 to 31 amino acid substitutions as well as by being devoid of phenylalanine. It contains substitutions at 9 positions which are invariant in the other 7 bird lysozymes of known sequence. Although the chachalaca is classified zoologically in the order Galliformes, which includes chickens and other pheasant-like birds, its lysozyme differs more from those of pheasant-like birds than do the lysozymes c of ducks. Phylogenetic analysis of the sequence comparisons confirms that the lineage leading to chachalaca lysozyme c separated from that leading to other galliform lysozymes c before the duck lysozyme c lineage did. This indicates a contrast between protein evolution and evolution at the organismal level. Immunological comparison of chachalacalysozyme c with other lysozymes of known sequence provides further support for the proposal that immunological cross-reactivity is strongly dependent on degree of sequence resemblance among bird lysozymes.103rd communication on lysozymes from the Laboratory of P. Jollès. Supported in part by grants from C.N.R.S. (ER 102), I.N.S.E.R.M. (Groupe de recherche U-116), N.S.F. (GB-42028X), and N.I.H. (GM-21509). 相似文献
8.
目的:评估不同类型的下颌骨骨折的手术入路及固定方法。方法:对于52例不同类型下颌骨骨折患者采用不同的口外或口内切口及相应的固定方法。结果:52例患者伤口全部一期愈合,51例咬合关系恢复到伤前咬合关系,1例出现咬合关系不良,X线检查骨折线队位良好。结论:对于不同部位的下颌骨骨折应采用相应的手术切口及固定方法,以获得最好的疗效。 相似文献
9.
PurposeSeveral magnetic resonance imaging (MRI) techniques exploit the difference in magnetic susceptibilities between tissues, but systematic measurements of tissue susceptibility are lacking. Furthermore, there is the question as to whether chemical fixation that is used for ex vivo MRI studies, affects the magnetic properties of the tissue. Here, we determined the magnetic susceptibility and water content of fresh and chemically fixed mouse tissue.MethodsMass susceptibility of brain, heart, liver and skeletal muscle samples were determined on a vibrating sample magnetometer at room temperature. Measurements at 50, 125, 200 and 295 K were performed to assess the temperature dependence of susceptibility. Moreover, we measured water content of fresh and fixed samples.ResultsAll samples show mass susceptibilities between −0.068 and −1.929 × 10−8 m3/kg, compared to −9.338 × 10−9 m3/kg of double distilled water. Heart tissue has a more diamagnetic susceptibility than the other tissues. Compared to fresh tissue, fixed tissue has a less diamagnetic susceptibility. Fixed tissue was not different in water content to fresh tissue and showed no consistent dependence of susceptibility with temperature, whereas fresh tissue shows a decrease to at least 125 K, indicative of a paramagnetic component.ConclusionsBiological tissues are diamagnetic in comparison to water, where the heart is more diamagnetic than the other tissues, with paramagnetic contributions. Fixation rendered tissue less diamagnetic compared to fresh tissue. Our measurements revealed differences in tissue susceptibility between VSM and QSM, inviting more research to compare susceptibility-based MRI methods with physical measurements of tissue susceptibility. 相似文献
10.
《Biotechnic & histochemistry》2013,88(2):112-113
PC10 is a monoclonal antibody to proliferating cell nuclear antigen, a nuclear protein associated with the cell cycle. We have evaluated the effects of tissue fixation on PC10 immunoreactivity in sections of paraffin embedded rat tissues. Immunoreactivity was well preserved in tissues after fixation with alcohol-based solutions for 3–24 hr. Fewer PC10-positive cells were detectable in samples fixed with formaldehydecontaining solutions compared with samples fixed with alcohol for the same time. Loss of PC10 immunoreactivity in formaldehyde fixed tissues was progressive, and quantifiable as early as after 3 hr fixation. Consequently, alcohol-based fixatives are strongly recommended for any immunocytochemical prospective study using PC10 antibody. In contrast, loss of PC10-immunoreactivity is always predictable, but difficult to quantitate, using formaldehyde fixed specimens. This aspect should be considered when using PC10 antibody in retrospective studies with routinely-processed archival material. 相似文献