首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   850篇
  免费   65篇
  2023年   4篇
  2022年   6篇
  2021年   11篇
  2020年   11篇
  2019年   15篇
  2018年   12篇
  2017年   24篇
  2016年   22篇
  2015年   31篇
  2014年   31篇
  2013年   60篇
  2012年   61篇
  2011年   67篇
  2010年   34篇
  2009年   33篇
  2008年   61篇
  2007年   59篇
  2006年   53篇
  2005年   61篇
  2004年   39篇
  2003年   47篇
  2002年   43篇
  2001年   17篇
  2000年   4篇
  1999年   11篇
  1998年   12篇
  1997年   9篇
  1996年   8篇
  1995年   1篇
  1994年   4篇
  1993年   2篇
  1992年   10篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   7篇
  1987年   3篇
  1986年   3篇
  1985年   8篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
  1969年   1篇
排序方式: 共有915条查询结果,搜索用时 812 毫秒
1.
2.
Pre- and postoperative intradermal administration of OK-432 enhanced the SU-PS skin reaction in patients with gastric cancer, but failed to prevent a fall in the NK activity induced by the operation.The change in NK activity was not associated with a change in the proportion of Leu 7-positive cells, but was related to Leu 11a-positive cells. Intradermal injection of OK-432 increased the proportion of Leu 7-positive cells in the patients in whom they accounted for less than 20% of lymphocyte population. The case was the same with Leu 11a-positive cells.Intravenous injection of OK-432 tended to increase suppressor-inducer T cells (CD4+2HA+ cells), B cells and Leu 7-positive cells. Particularly, the proportions of OK-M1-positive cells and MHC class II antigen-positive cells increased in all patients. Immunotherapy with OK-432 given intravenously at a dose of 0.1 KE appeared to be safe because no side effects were essentially observed.  相似文献   
3.
Observations on granulocyte peroxidase of 123 teleosts are reported and correlated with previous studies to put occurrence of fish granulocyte peroxidase in a phylogenetic perspective. Eosinophil peroxidase occurs in archaic groups such as lungfish and sturgeons, but is usually weak and infrequently observed in chondrichthyans, and in teleosts occurs in some elopomorphs, is consistently observed in stomiiforms, is rarely observed and usually weak in acanthopterygians and absent from salmoniforms, scopelomorphs and paracanthopterygians. Peroxidase is absent from lungfish and sturgeon neutrophils, is present in neutrophils of some elopomorphs and clupeimorphs. both of which are basal teleost groups, but in salmoniforms and higher teleosts is consistently observed in neutrophils. although often weak in pleuronectiforms.
Loss of eosinophil peroxidase and development of neutrophil peroxidase in teleosts may be due to inefficient phagocytosis and loss of peroxidase with degranulation in eosinophils, being superseded by concentration of peroxidase in phagosomes in neutrophils.  相似文献   
4.
A new plasmid-mediated beta-lactamase (FPM-1) with an isoelectric point of 7.2 and a molecular weight of 26,000 was found in a cefuroxime-resistant clinical isolate of Proteus mirabilis strain 6003. FPM-1 can be classified as a type I oxyimino-cephalosporinase on the basis of its substrate specificity and inhibition pattern by clavulanic acid etc., and its conferred resistance on both the strain and transconjugants against most oxyme-type cephalosporins as well as the older ones but not against cefamycins and a few exceptional oxyme-type cephalosporins such as ceftizoxime, ceftazidime and cefixime. In a murine systemic infection model, only these FPM-1-stable drugs exhibited protective activity against the FPM-1-producing P. mirabilis 6003 similar to that against a nonproducing derivative strain. The FPM-1-mediated cefuroxime resistance in P. mirabilis 6003 was transferred to co-infected Escherichia coli 7004 at frequencies between 3.8 x 10(-3) and 4.0 x 10(-2) in a murine ascending urinary tract infection model. In the same infection model due to the FPM-1-producing E. coli transconjugant, FPM-1-stable cefixime was significantly more effective than FPM-1-labile cefteram pivoxil, although both drugs had similar therapeutic effect against its FPM-1-nonproducing counterpart strain.  相似文献   
5.
We have developed a liquid chromatographic method which uses electrochemical detection for the simultaneous quantitation of histamine and N tau-methylhistamine in rat brain. The amines are derivatized with the water-soluble Bolton-Hunter reagent (sulfo B-H). Perchloric acid extracts of rat brains are chromatographed on a strong cation-exchange resin. The eluate is evaporated and allowed to react with sulfo B-H at pH 9.8 at room temperature. The derivatization is complete after 30 s vortexing. The derivatives are purified using a cellulose-phosphate fibrous cation exchanger. They are quantified with an electrochemical detector at a potential of 0.56 V after preoxidizing the sample at 0.47 V. The derivatives of histamine, N tau-methylhistamine, and N alpha-methylhistamine are completely separated without interfering peaks. Since no N alpha-methylhistamine was detected in rat brain it was used as an internal standard. The detection limits are 0.1 pmol of histamine and 0.2 pmol of N tau-methylhistamine. The precision of this method is high, with within-run and between-run coefficients of variation of 2-7% and linearity of 0.999. Both histamine and N tau-methylhistamine peak heights increased significantly and selectively after treatment with pargyline. Because of the high sensitivity, accuracy, and precision, the histamine and N tau-methylhistamine contents of single nuclei of the rat hypothalamus can be routinely quantified.  相似文献   
6.
Virchows Archiv B Cell Pathology - Paget cells from cases of mammary and extramammary Paget’s disease were examined for carcinoembryonic antigen (CEA) and CEA-related antigens by the...  相似文献   
7.
Abstract: In this study, we immunohistochemically examined the several constituents of senile plaques (SPs) and cerebral amyloid angiopathy (CAA) in aged cynomolgus monkeys. Apolipoprotein E (apoE) deposited in all mature plaques and CAA, and in half of the diffuse plaques. Alpha-1-antichymotripsin (αACT) deposited in half of the mature plaques and in one third of the CAA. Amyloid precursor protein (APP), ubiquitin (Ub), and microtubule-associated protein-2 (MAP-2) accumulated in the swollen neurites of mature plaques. Glial fibrillary acidic protein (GFAP) was detected in the astrocytes and their processes surrounding the mature plaques. Tau was detected in neither the SPs nor CAA. Therefore, mature plaques involved extracellular Aβ, apoE, and αACT, and also astrocytes and swollen neurites. However, diffuse plaques involved only extracellular Aβ and apoE. Since these features, except for tau, were consistent with those in humans, this animal model will be useful for studying the pathogenesis of cerebral amyloid deposition.  相似文献   
8.
A genomic clone encoding an auxin-binding protein (ABP) fromthe endoplasmic reticulum was isolated from Arabidopsis thaliana.The ABP gene consisted of 5 exons and 4 introns and encodeda polypeptide of 198 residues. A gene encoding the 7SL RNA ofthe signal recognition particle was located downstream of theABP gene. 4Recipient of a scholarship from the National Education Commission,People's Republic of China.  相似文献   
9.
10.
Abstract: We previously reported that an endogenous activating substance different from bovine serum albumin, phospholipids and heparin, exists in the extract from bovine pineal glands and that this substance interacts with tryptophan-5-monooxygenase under reducing conditions with sulfhydryl reagents, to stimulate monooxygenase activity. The present paper reports that the activating substance is of peptide nature; that it is sensitive to trypsin-digestion; and that it does not change the apparent K m's for substrates, L-tryptophan and oxygen, and coenzyme, reduced biopterin or DMPH4: but that it increases the V max 1.5- to 2.3-fold. These results suggest that an activating protein, present in some particles of the cell structure, activates tryptophan-5-monooxygenase under the regulation of a sulfhydryl compound. The apparent K m's for reduced biopterin and DMPH4 were 77.2μM and 294 μM, respectively. The apparent K m's for L-tryptophan and oxygen with reduced biopterin were 15.0 μM and 4.7%, respectively: with DMPH4, they were 11.0 μM and 8.5%, respectively. Significant inhibition of both L-tryptophan and oxygen was observed with reduced biopterin, but not with DMPH4 (at the tested concentrations of up to 0.5 MM and 20%, respectively).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号