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   119篇
  免费   23篇
  国内免费   4篇
  2023年   3篇
  2021年   3篇
  2020年   6篇
  2019年   5篇
  2018年   4篇
  2017年   5篇
  2015年   2篇
  2014年   8篇
  2013年   5篇
  2012年   9篇
  2011年   7篇
  2010年   1篇
  2009年   3篇
  2008年   1篇
  2007年   7篇
  2006年   4篇
  2005年   4篇
  2004年   5篇
  2003年   7篇
  2001年   3篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   4篇
  1996年   5篇
  1995年   3篇
  1994年   9篇
  1993年   1篇
  1991年   2篇
  1990年   4篇
  1989年   2篇
  1988年   4篇
  1987年   3篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1976年   2篇
  1974年   1篇
  1971年   1篇
  1970年   1篇
排序方式: 共有146条查询结果,搜索用时 31 毫秒
101.
The cytoskeleton, capsule and cell ultrastructure were studied during the cell cycle of Cryptococcus laurentii. In an encapsulated strain, cytoplasmic microtubules and a mitotic spindle were detected. Mitosis was preceded by migration of the nucleus into the bud. F-actin failed to be visualised by rhodamine-phalloidin (RhPh) in encapsulated cells and therefore an acapsular strain was used. The following actin structures were found: actin dots, actin cables and cytokinetic ring. Ultrastructural studies showed the presence of a nucleus in the bud before mitosis. A collar-shaped structure was seen at the base of bud emergence. A lamellar cell wall and a rough outer surface of the cells were detected. Cytoskeletal structures found in C. laurentii are similar to those in Cryptococcus neoformans, which is a serious human pathogen.  相似文献   
102.
The seed-feeding jewel bug, Agonosoma trilineatum (F.), is an introduced biological control agent for bellyache bush, Jatropha gossypiifolia L. To quantify the damage potential of this agent, shadehouse experiments were conducted with individual bellyache bush plants exposed to a range of jewel bug densities (0, 6 or 24 jewel bugs/plant). The level of abortion of both immature and mature seed capsules and impacts on seed weight and seed viability were recorded in an initial short-term study. The ability of the jewel bug to survive and cause sustained damage was then investigated by measuring seed production, the survival of adults and nymph density across three 6-month cycles. The level of seed capsule abortion caused by the jewel bug was significantly affected by the maturity status of capsules and the density of insects present. Immature capsules were most susceptible and capsule abortion increased with jewel bug density. Similarly, on average, the insects reduced the viability of bellyache bush seeds by 79% and 89% at low and high densities, respectively. However, sustaining jewel bug populations for prolonged periods proved difficult. Adult survival at the end of three 6-month cycles averaged 11% and associated reductions in viable seed production ranged between 55% and 77%. These results suggest that the jewel bug has the potential to reduce the number of viable seeds entering the soil seed bank provided populations can be established and maintained at sufficiently high densities.  相似文献   
103.
目的:探讨红金消结胶囊联合米非司酮治疗子宫肌瘤的疗效及对血清血管生成素-2(Ang-2)、表皮生长因子(EGF)、核因子-κBp65(NF-κBp65)水平的影响。方法:选择我院2017年5月至2018年5月接诊的103例子宫肌瘤患者,通过随机数表法将其分为观察组53例和对照组50例。对照组给予米非司酮治疗,观察组在对照组基础上联合红金消结胶囊治疗,两组患者在月经期间停药,均连续治疗3个月。比较两组的临床疗效、治疗前后血清Ang-2、EGF、NF-κBp65、卵泡雌激素(FSH)、促黄体生成素(LH)、雌二醇(E2)水平、子宫体积与瘤体情况的变化及不良反应的发生情况。结果:治疗后,观察组临床疗效总有效率为94.34%,显著高于对照组78%,P0.05),血清Ang-2、EGF、NF-κBp65、FSH、LH、E2水平均显著低于对照组(P0.05),子宫体积和子宫肌瘤体积均小于对照组(P0.05)。两组不良反应发生率比较差异无统计学意义(P0.05)。结论:红金消结胶囊联合米非司酮治疗子宫肌瘤的临床疗效显著优于单用米非司酮治疗,其可更显著改善患者性激素水平,缩小子宫和子宫肌瘤的体积,这可能与降低血清Ang-2、EGF、NF-κBp65水平有关。  相似文献   
104.
An experimental oil adjuvant vaccine was developed against haemorrhagic septicaemia, a disease of cattle and buffalo caused by Pasteurella multocida serotype B and E. Mineral oil, Mercol 52, was used as adjuvant together with Span 85 and Tween 85 as emulsifiers. The vaccine was evaluated by single dose intramuscular immunisation of 1–2 year old buffalo calves. IgG and IgM class antibodies were determined by ELISA. The group of animals immunised with the experimental oil adjuvant vaccine showed a high titre of the IgG class of antibodies measured at 300 days post vaccination. To compare the protective efficacy of the vaccine with the commonly used broth bacterin, another group of buffalo calves was immunised by broth bacterin. This group showed a low level of IgG antibodies. Protection was assessed by challenge with 109 viable bacteria of P. multocida type B:2,5 administered subcutaneously, 250 days post vaccination. Animals vaccinated with the experimental oil adjuvant vaccine were fully protected. The other groups of animals, vaccinated with broth bacterin or used as control (non-vaccinated), developed symptoms of haemorrhagic septicaemia. A strong relationship between IgG but not IgM class antibody level and resistance to challenge was observed. The experiment demonstrated that the experimental oil adjuvant vaccine was superior to broth bacterin in providing protection against experimental haemorrhagic septicaemia in young buffalo calves beyond 250 days.  相似文献   
105.
Representatives of many plant and animal taxa enclose their embryos within some form of protective structure. Inter- and intraspecific differences in the morphology of these egg coverings may have profound effects on the development and survival of encapsulated embryos, yet in many taxa little is known about the causes or potential consequences of this variation. Comparisons of capsule morphology among populations of the rocky shore gastropod, Nucella emarginata, revealed significant variation in the thickness of capsule walls, the only barrier separating developing embryos from the external environment. Laboratory experiments demonstrated that thicker-walled capsules were more resistant to predation by a co-occurring isopod, Gnorimosphaeroma oregonense, than were thinner-walled capsules. Control experiments confirmed that these differences in vulnerability were not caused by differences in the palatability of the capsule wall or attractiveness of the capsule contents. The actual mechanism by which thick-walled capsules differentially protect developing embryos remains unclear, although decreased vulnerability of thick-walled capsules to these isopods may simply result from increased handling time by predators. Subtle differences in capsule morphology thus appear to have substantial effects on the survival of encapsulated embryos. Hence, predators may have played an important role in selecting for the production of thick-walled capsules among populations of N. emarginata.  相似文献   
106.
Summary Oogenesis has been followed with the electron microscope in 2 strains of the malaria mosquito Anopheles gambiae, from the emergence of the adult (oocytes at leptonema) till shortly before the oocytes are ready for oviposition. After pachynema the chromosomes form a karyosphere and a fibrous capsule develops around it. Work on other mosquitoes suggests that the capsule may be related to the synaptonemal complexes. Both Anopheles strains contain at some time an extrachromosomal (not DNA-containing) body comparable to the karyosphere in size. Clusters of granules are present at the surface of the nucleolus and free in the nucleoplasm. Tentative results indicate that they may contain DNA. During oogenesis the nucleolus becomes very large, mainly because of proliferation of the nucleolonema. Towards the end of oocyte development the nucleus assumes the large canoe-shape also seen in Aedes and Culex. Nucleolonema traverse the entire nucleus, and modified granular clusters are found throughout.  相似文献   
107.
The shape and the mode of dehiscence of the capsule had been regarded as good differential characters betweenAcanthophyllum and related genera.—Studies of these characters, including the shape of the ovary, in species ofAcanthophyllum, Diaphanoptera, Ochotonophila andScleranthopsis show, however, that they cannot be used as differential characters for the genusAcanthophyllum. Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.  相似文献   
108.
摘要 目的:研究芪苈强心胶囊联合左卡尼汀注射液对慢性心力衰竭的疗效。方法:选择2016年1月~2019年1月我院收治的85例慢性心力衰竭患者,随机分为两组。对照组静脉滴注左卡尼汀注射液,观察组联合口服芪苈强心胶囊。检测两组治疗前后的心功能、心室重构、血浆脑钠素 N 端前体肽(N-terminal pro peptide of brain natriuretic peptide,NT-pro BNP)、高敏 C 反应蛋白(High sensitive C-reactive protein,hs-CRP)水平。结果:观察组治疗的总有效率为88.09 %(37/42),明显高于对照组的67.44%(29/43)(P<0.05)。治疗前,两组的左心室舒张末期内径(End diastolic diameter of left ventricle,LVEDd)、心率(heart rate,HR)、左心室收缩末内径(Left ventricular end systolic diameter,LVESd)、左室射血分数(Left ventricular ejection fraction,LVEF)、心排血量(Cardiac output,CO)和E峰/A峰的比值(E peak /A peak,E/A)均无显著差异(P>0.05);治疗后,两组的LVEDd、HR和LVESd均明显降低(P<0.05),LVEF、CO和E/A均明显升高(P<0.05),且观察组上述指标明显优于对照组(P<0.05)。治疗前,两组的血浆NT- pro BNP、hs- CRP水平比较无差异(P>0.05);治疗后,两组的血浆NT- pro BNP、hs- CRP水平均明显降低(P<0.05),且观察组明显低于对照组(P<0.05)。对照组发生胃肠道反应3例,头痛3例,不良反应的发生率为13.95 %;观察组发生胃肠道反应4例,头痛3例,不良反应的发生率为16.67 %。两组不良发应的发生情况无统计学意义(P>0.05)。结论:芪苈强心胶囊联合左卡尼汀注射液能改善慢性心力衰竭患者的心室重构及心功能,降低炎症标志物和神经内分泌激素水平,值得进行推广。  相似文献   
109.
摘要 目的:探讨超声造影对甲状腺癌包膜侵犯、淋巴结转移的诊断价值及其与血清高迁移率族蛋白1(HMGB-1)、可溶性白细胞介素-2受体(sIL-2R)相关性研究。方法:选取2019年2月至2020年8月本院收治的156例甲状腺结节患者作为研究对象。所有患者均经病理证实,根据病理结果提示包膜侵犯情况可分为侵犯组(86例,55.13%)与未侵犯组(70例,44.87%);另外根据病理结果提示淋巴结转移情况也分为转移组(92例,58.97%)与未转移组(64例,41.03%)。术前均行常规超声、超声造影以及血清HMGB-1、sIL-2R水平检测。比较常规超声、超声造影诊断甲状腺包膜侵犯、淋巴结转移的诊断效能,并分析其与血清HMGB-1、sIL-2R水平的相关性。结果:常规超声、超声造影对甲状腺癌包膜侵犯、淋巴结转移的诊断结果差异均具有统计学意义(P<0.05)。超声造影诊断甲状腺癌包膜侵犯的准确性、敏感度显著高于常规超声(P<0.05),而两种检查方式之间特异度、阳性预测值以及阴性预测值的差异无统计学意义(P>0.05);超声造影诊断甲状腺癌淋巴结转移的准确性、敏感度、特异度、阳性预测值以及阴性预测值均显著高于常规超声(P<0.05)。甲状腺癌包膜侵犯组、淋巴结转移组的血清HMGB-1、sIL-2R水平分别显著高于未侵犯组、未转移组(P<0.05)。结论:超声造影对甲状腺癌包膜侵犯、淋巴结转移具有一定诊断价值,而与血清HMGB1、sIL-2R水平具有相关性。因此,术前行超声造影检查以及血清HMGB1、sIL-2R水平检测对甲状腺癌患者包膜侵犯、淋巴结转移有一定提示作用,可对对临床治疗方案的选择具有重要价值。  相似文献   
110.
Poor survival of cryopreservation by equine expanded blastocysts may involve low penetration of the embryonic capsule by cryoprotective agents (CPAs). This study characterized the permeation and accumulation rates of the CPAs ethylene glycol (EG) and glycerol (GLY) across isolated capsule in vitro, using a dual-chambered Valia-Chien permeation apparatus. Pieces of Days 14 to 18 ±1 capsules separated media in the “donor” chamber containing either 1.5 M EG (n = 6), 0.74 M EG (n = 5), 0.87 M GLY (n = 7), or 0.15 M NaCl (saline, SAL) (n = 6), from the “recipient” chamber. Concentrations of CPA, determined by gas chromatography, allowed calculation of the capsule's apparent permeability (Papp) to those CPAs. Permeation of capsule by 1.5 M EG was significantly more rapid than by 0.87 M GLY, or 0.74 M EG; permeation by both CPAs was significantly slower than by SAL. Accumulation of CPA in the recipient chamber depended more on initial donor chamber concentration, rather than type, of CPA. Accumulation rates for CPAs and SAL were linear only when capsule was present, demonstrating that their permeation through capsule was more complex than simple diffusion. Successful cryopreservation of equine expanded blastocysts has been previously linked to lengths of step-wise exposures to CPAs. Based on the present results, we inferred that alternative CPAs, more capable of permeating the capsule, or alternative methods of ensuring CPA entry into the cells, may also be required.  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