全文获取类型
收费全文 | 7263篇 |
免费 | 517篇 |
专业分类
7780篇 |
出版年
2021年 | 60篇 |
2019年 | 68篇 |
2018年 | 76篇 |
2017年 | 61篇 |
2016年 | 96篇 |
2015年 | 153篇 |
2014年 | 172篇 |
2013年 | 365篇 |
2012年 | 321篇 |
2011年 | 336篇 |
2010年 | 180篇 |
2009年 | 196篇 |
2008年 | 340篇 |
2007年 | 311篇 |
2006年 | 337篇 |
2005年 | 333篇 |
2004年 | 315篇 |
2003年 | 317篇 |
2002年 | 319篇 |
2001年 | 297篇 |
2000年 | 292篇 |
1999年 | 237篇 |
1998年 | 94篇 |
1997年 | 84篇 |
1996年 | 72篇 |
1995年 | 73篇 |
1994年 | 64篇 |
1993年 | 76篇 |
1992年 | 163篇 |
1991年 | 172篇 |
1990年 | 157篇 |
1989年 | 148篇 |
1988年 | 146篇 |
1987年 | 127篇 |
1986年 | 102篇 |
1985年 | 82篇 |
1984年 | 103篇 |
1983年 | 83篇 |
1982年 | 49篇 |
1981年 | 47篇 |
1980年 | 58篇 |
1979年 | 96篇 |
1978年 | 69篇 |
1977年 | 75篇 |
1976年 | 41篇 |
1975年 | 41篇 |
1974年 | 43篇 |
1973年 | 45篇 |
1972年 | 43篇 |
1968年 | 34篇 |
排序方式: 共有7780条查询结果,搜索用时 0 毫秒
11.
12.
Masanori Shinzato Mikihiro Shamoto Satoru Hosokawa Chiyuki Kaneko Akido Osada Miyuki Shimizu Asako Yoshida 《Biotechnic & histochemistry》1995,70(3):114-118
The present study shows that Langerhans cells can be differentiated from Interdigitating cells at the light microscopic level. Superficial lymph nodes and skin taken from necropsies and the lymph nodes of dermatopathic lymphadenopathy (DPL) were used for this experiment. Sections of lymph node and skin were embedded using the acetone, methyl benzoate and xylene (AMeX) method and dendritic cells were immunostained with anti S-100 protein antibody (S-100, and OKT-6 (CD1a) using the restaining method. Langerhans cells in the skin were positive for both CD1a and S-100. Dendritic cells positive for both CD1a and S-100, and dendritic cells positive for S-100, but not for CD1a were observed in superficial lymph nodes. In normal superficial lymph nodes, there were more interdigitating cells than Langerhans cells. The majority of the dendritic cells in the DPL were Langerhans cells. We conclude that the S-100 and CD1a positive cells are Langerhans cells, and the S-100 positive-CD1a negative cells are interdigitating cells. 相似文献
13.
K Yoshida T Sakurada H Kitaoka H Fukazawa N Kaise K Kaise M Yamamoto S Saito K Yoshinaga 《Endocrinologia japonica》1983,30(2):211-217
Monodeiodination of T4 to T3 and rT3 in the intact cells of dog renal tubuli and glomeruli was investigated. The tubuli and glomeruli were obtained by a sieve method. T4 (2 micrograms/ml) was incubated in Tris-HCl buffer, pH 7.5, with renal cells (180 micrograms protein/ml) and 5 mM DTT for 1 h at 37 degrees C and the T3 and rT3 generated during incubation were measured by specific radioimmunoassays. In order of decreasing activity, dog renal cortical tubuli, cortical homogenate, glomeruli and medullary tubuli were capable of converting T4 to T3. Net rT3 production from T4 in cortical tubuli was also greater than that in cortical homogenate. The conversion of T4 to T3 and also to rT3 in cortical tubuli was enzymatic in nature, since the reactions showed dependence on time and protein concentration; instability to heating; temperature and pH optimum. The production of T3 and rT3 from T4 was maximum at pH 6.5 and at pH 9.5, respectively, indicating that two different enzymic systems, a 5- and a 5'-monodeiodinase, might be involved in the deiodination of the tyrosyl and the phenolic ring of T4 in dog kidney. 相似文献
14.
15.
16.
M Sobue J Takeuchi T Fukatsu T Nagasaka N Nakashima T Ogura T Katoh K Yoshida 《Stain technology》1989,64(1):43-47
Dermatan sulfate proteoglycan chains were detected in tissue sections treated with chondroitin B-lyase (0.01 units/ml) in 20 mM Tris-HCl (pH 8.0) for 1 hr, followed by staining with antibody 9A2 specific for unsaturated uronic acid coupled to N-acetylgalactosamine-4 sulfate. In contrast, after treatment with chondroitin B-lyase, no positive staining was observed with antibodies 3B3 and 1B5 which react to the unsaturated uronic acid coupled to N-acetylgalactosamine 6-sulfate and unsaturated uronic acid coupled to N-acetylgalactosamine, respectively. The distribution of dermatan sulfate thus revealed was confirmed by comparison with that found by monoclonal antibody 6B6 which reacts with small proteoglycans carrying dermatan sulfate side chains. The localization of positive staining in fibrous connective tissues was almost identical with these two procedures. 相似文献
17.
Isolation and partial characterization of a novel form of low molecular weight kininogen from guinea pig plasma 总被引:1,自引:0,他引:1
Two kinds of low molecular weight kininogen (termed LK1 and LK2) were isolated from pooled plasma of guinea pigs. When polyclonal antisera raised against the individual proteins were used, immunological cross-reactions were observed between LK1 and high molecular weight kininogen (HK), but not either between LK1 and LK2 or between LK2 and HK. After tissue injury, plasma level of LK1 doubled while those of LK2 and HK remained relatively unchanged. 相似文献
18.
We found that the incidence of spontaneous myeloid leukemia in C3H/He male mice was less than 1%, but it could be increased considerably by total-body X irradiation. The induction of myeloid leukemia was seen to increase after doses from 0.47 Gy (3%) to 2.84 Gy (23.9%), and then decrease after a dose of 4.73 Gy (13.6%). The administration of prednisolone acetate (synthesized glucocorticoid) after irradiation resulted in a significant increase in the incidence of myeloid leukemia from 23.9 to 38.5% after a dose of 2.84 Gy; however, corticosterone, a glucocorticoid secreted by cells, did not have such an enhancing effect. 相似文献
19.
Bacillus subtilis inositol dehydrogenase-encoding gene (idh): sequence and expression in Escherichia coli. 总被引:2,自引:0,他引:2
The Bacillus subtilis inositol dehydrogenase (Idh)-encoding gene (idh) was cloned in the B. subtilis temperate phage, rho 11, and then in Escherichia coli plasmids (pBR322 and pUC118). The nucleotide sequence of the idh gene, which consists of 344 codons and whose product has an Mr of 38,351, was determined. E. coli, bearing pIOL05d15, in which expression of the idh gene is under the control of the lac promoter of pUC118, overproduced an active Idh to approx. 20% of total protein upon addition of isopropyl-beta-D-thiogalactopyranoside. This overproduced enzyme cross-reacted with an anti-Idh antibody, and exhibited the same Mr and substrate specificity as those of the B. subtilis enzyme. 相似文献
20.
New preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for fatty acids and derivatives 总被引:6,自引:0,他引:6
A preparation method for 9-anthryldiazomethane (ADAM) as a fluorescent labeling reagent for carboxylic acids is described. 9-Anthraldehyde hydrazone is oxidized with an organic oxidant, N-chlorosuccinimide, in an organic solvent such as ethyl acetate to give ADAM, and then the reaction mixture is directly used as the reagent solution for the derivatization of carboxylic acids. Both the oxidation and the derivatization reaction are carried out at room temperature, and an aliquot of the derivatization mixture is directly injected into a chromatograph. 9-Anthrylmethyl ester derivatives formed from ADAM and various carboxylic acids are sufficiently separated on a reversed-phase column and are sensitively detected fluorometrically. The present method was applied to the high-performance liquid chromatographic determination of long and short chain fatty acids, keto acids, and hydroxy acids. 相似文献