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   123篇
  免费   9篇
  2023年   3篇
  2022年   6篇
  2021年   5篇
  2020年   5篇
  2019年   8篇
  2018年   3篇
  2017年   4篇
  2016年   5篇
  2015年   2篇
  2014年   4篇
  2013年   4篇
  2012年   3篇
  2011年   9篇
  2009年   3篇
  2008年   11篇
  2007年   5篇
  2006年   5篇
  2005年   6篇
  2004年   5篇
  2003年   1篇
  2002年   4篇
  2001年   5篇
  2000年   1篇
  1999年   3篇
  1997年   1篇
  1992年   4篇
  1991年   1篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   5篇
  1983年   3篇
排序方式: 共有132条查询结果,搜索用时 15 毫秒
11.
The aim of the study was a cross-cultural comparison of personality traits between individuals from two very different cultures and refugees who resettled several years before from one to the other. Four hundred forty four Swedish individuals of the normal population; and 100 Iranian refugees in Sweden, and a group of 335 individuals from Tehran, capital of Iran, were investigated by means of the Temperament and Character Inventory, a questionnaire to assess temperament and character Iranians are those that are most frequently correctly classified followed by the Swedish based on temperament scores by means of a Discriminance analyses. Iranian refugees in Sweden were classified to about 50 per cent as Swedish and to slightly more then one-third as Iranians. Especially concerning character, 4 per cent only could be correctly classified as refugees. The results give some perspective on the adaptation process and personality changes in refugees several years after resettlement in another country with a complete different culture.  相似文献   
12.
A series of 1,2,4-triazolylchromanone oxime ethers were synthesized and tested for in vitro antifungal activity. Many of these derivatives exhibit high activity against Candida albicans, Saccharomyces cerevisiae, Aspergillus niger and Microsporum gypseum.  相似文献   
13.
Two types of xylanase gene, XYN11A (XYL1) and XYN11B (XYL2), were amplified by PCR and partially sequenced in four phytopathogenic species of the ascomycete fungal genus Cochliobolus (anamorph genus Bipolaris). Three of the species, C. heterostrophus (B. maydis), C. sativus (B. sorokiniana), and Bipolaris sorghicola (no teleomorph known), are interrelated; the fourth, C. spicifer (B. spicifera), was found, through analysis of the 5.8S RNA and internal transcribed spacer (ITS) sequences of its ribosomal DNA, to be more distantly related to the other three. Isolates from all four species contain orthologous XYN11A and XYN11B genes, but a set of laboratory strains of C. heterostrophus gave no product corresponding to the XYN11B gene. The patterns of evolution of the two xylanase genes and ribosomal DNA sequences are mutually consistent; the results indicate that the two genes were present in the common ancestor of all Cochliobolus species and are evolving independently of each other. Received: 12 July 2001 / Accepted: 6 March 2002  相似文献   
14.
The effect of cadmium on induction of oxidative stress in rat submandibular saliva and protective role of increasing intracellular cAMP and cGMP by use of specific phosphodiesterase inhibitors, theophylline and sildenafil were investigated. Pure submandibular saliva was collected intraorally by micro polyethylene cannula from anaesthetized rats using pilocarpine as secretagogue. Acute administration of cadmium (10 mg/kg) caused significant oxidative stress by increasing lipid peroxidation by-products (thiobarbituric reactive substances, TBARS) and decreasing total thiols and total antioxidant power of the saliva. Concurrent therapy of rats by theophylline (25 mg/kg) and sildenafil (5 mg/kg) prevented cadmium-induced oxidative stress in saliva. Theophylline and sildenafil inhibited cadmium-induced increase in lipid peroxidation and decrease in total thiols and antioxidant power. It is concluded that cadmium administration results in oxidative stress in rat submandibular saliva, which can be protected by concurrent administration of specific cyclic nucleotide phosphodiesterase inhibitors.  相似文献   
15.
A series of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl) derivatives of piperazinyl quinolones was synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit high activity against Gram-positive bacteria; Staphylococcus aureus and Staphylococcus epidermidis, comparable or more potent than their parent N-piperazinyl quinolones norfloxacin and ciprofloxacin as reference drugs. The SAR of this series indicates that both the structure of the benzyl unit and the S or SO(2) linker dramatically impact antibacterial activity.  相似文献   
16.
The parasitoids associated with the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, were investigated at three pistachio plantations in Rafsanjan, Iran. Of the 6504 wasps emerging from mummified psyllids, 46% were the primary parasitoid Psyllaephagus pistaciae Ferrière, and the remaining 54% represented six species of hymenopterous hyperparasitoids, including Chartocerus kurdjumovi (Nikol’skaja), Marietta picta (André), Pachyneuron aphidis (Bouché), Pachyneuron muscarum (Linnaeus), Psyllaphycus diaphorinae (Hayat), and Syrphophagus aphidivorus (Mayr). Lysiphlebus fabarum Marshall, the parasitoid of Aphis gossypii Glover and Aphis craccivora Koch present on weeds, was found to be an alternative host for three major hyperparasitoids of A. pistaciae. The most abundant hyperparasitoid was S. aphidivorus, appearing during the growing season in all trial locations on psyllids and aphids in pistachio orchards. The weed-infesting aphids, along with their primary parasitoid, can act as a reservoir of A. pistaciae secondary parasitoids. Therefore, parasitized aphids allow populations of secondary parasitoids to increase and consequently to apply higher pressure on P. pistaciae. We detected that two primary parasitoid species, including P. pistaciae and L. fabarum, attacking different species of hosts interact indirectly through shared secondary parasitism. It is suggested that the community structure of A. pistaciae may be influenced by apparent competition, although more work is needed to provide firm evidence.  相似文献   
17.
Trefoil factors (TFFs) are protease-resistant peptides that promote epithelial cell migration and mucosal restitution during inflammatory conditions and wound healing in the gastrointestinal tract. To date, the molecular mechanism of TFFs action and their possible role in tumor progression are unclear. In the present study, we observed that premalignant human colonic PC/AA/C1 and canine kidney MDCK epithelial cells are not competent to invade collagen gels in response to exogenously added TFFs (pS2, spasmolytic polypeptide, and intestinal trefoil factor). In contrast, activated src and RhoA exert permissive induction of invasion by the TFFs that produce similar parallel dose-response curves in src-transformed MDCKts.src and PCmsrc cells (EC50=20-40 nM). Cell scattering is also induced by TFFs in MDCKts.src cells. Stable expression of the pS2 cDNA promotes constitutive invasiveness in MDCKts.src-pS2 cells and human colonic HCT8/S11-pS2 cells established from a sporadic tumor. Furthermore, we found that TFF-mediated cellular invasion is dependent of several signaling pathways implicated in cell transformation and survival, including phosphoinositide PI3'-kinase, phospholipase C, protein kinase C, and the rapamycin target TOR. Constitutive and intense expression of pS2 was revealed by Western blot analyses and immunohistochemistry in human colorectal tumors and their adjacent control mucosa during the neoplastic progression, from the adenoma to the liver metastases. Our studies indicated that TFFs can be involved in cell scattering and tumor invasion via autocrine loops and may serve as potential targets in the control of colon cancer progression.  相似文献   
18.
A Prost  S Emami  C Gespach 《FEBS letters》1984,177(2):227-230
Short-term treatment of cultured HGT-1 cells with histamine produced a time-dependent (half-life: 20 min) and homologous desensitization of histamine H2 receptor activity mediating cAMP generation in HGT-1 cells and gastric acid secretion in normal gastric mucosa. Histamine treatment resulted in loss of response of the adenylate cyclase to histamine in purified plasma membranes, but had no effect on basal, vasoactive intestinal peptide (VIP)- or NaF-stimulated enzyme activities. We propose that the desensitization of gastric histamine H2 receptor by histamine evidenced in cellular or subcellular preparations from HGT-1 cells could be involved in the physiological regulation and pharmacological control of gastric cell function in man.  相似文献   
19.
20.
An association between a hypercoagulable state and Mendelian susceptibility to mycobacterial disease (MSMD) has been established in a few studies; resultant thrombosis is considered rare. In a case‐control study, the prevalence of factor V Leiden, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) C677T, A1298C mutations were investigated in mycobacterium‐infected patients. The study comprised 30 patients with mycobacterial infections (invasive, disseminated and/or recurrent infections with Bacille Calmette–Guerin or non‐tuberculosis mycobacteria and Mycobacterium Tuberculosis with positive results for acid‐fast bacilli and tuberculin skin tests) and 30 normal healthy controls. Forty female (66.7%) and 20 male subjects (33.3%) aged from 3 to 70 years were recruited into this study. Genotyping of targeted genes was performed by RT‐PCR and cytokine TNF‐α concentrations were quantified using a commercially available ELISA kit. Significant associations between mycobacterial infection and TNF‐α production after stimulating peripheral blood mononuclear cells with LPS alone and with IFN‐γ plus LPS were identified. Moreover, genotyping analysis in the studied population revealed a significant association between MTHFR c.677C>T (OR, 3.28; 95% CI, 1.35–7.92; P < 0.05), MTHFR c.1298A>C (OR, 2.33; 95% CI, 1.10–4.93; P < 0.05) and mycobacterial infection in affected patients, indicating susceptibility to venous thromboembolism according to previous studies. Additionally, mycobacterium‐infected patients had a significantly greater prevalence of MTHFR C677T and A1298C mutations than controls.  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