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   965篇
  免费   74篇
  2023年   9篇
  2022年   17篇
  2021年   25篇
  2020年   19篇
  2019年   14篇
  2018年   12篇
  2017年   28篇
  2016年   30篇
  2015年   29篇
  2014年   52篇
  2013年   55篇
  2012年   62篇
  2011年   66篇
  2010年   38篇
  2009年   35篇
  2008年   48篇
  2007年   42篇
  2006年   36篇
  2005年   28篇
  2004年   48篇
  2003年   29篇
  2002年   21篇
  2001年   19篇
  2000年   28篇
  1999年   30篇
  1998年   13篇
  1996年   8篇
  1995年   9篇
  1994年   6篇
  1993年   7篇
  1992年   7篇
  1991年   13篇
  1990年   6篇
  1989年   7篇
  1988年   11篇
  1987年   10篇
  1986年   6篇
  1984年   7篇
  1983年   9篇
  1982年   7篇
  1981年   6篇
  1979年   10篇
  1977年   5篇
  1976年   7篇
  1975年   10篇
  1974年   13篇
  1972年   4篇
  1971年   3篇
  1970年   7篇
  1969年   3篇
排序方式: 共有1039条查询结果,搜索用时 31 毫秒
51.
52.
Journal of Ichthyology - The present study reports the first record of the rearfin flying fish, Cypselurus opisthopus (Bleeker, 1865), in the south-eastern Arabian Sea based on a single specimen...  相似文献   
53.
Coral Reefs - Epilithic algae are a ubiquitous component of coral reefs. Components of the epilithic algal matrix (EAM) can have a significant influence on coral settlement and benthic feeding by...  相似文献   
54.
Background:This study correlates the serum levels of sCD95 & TNF-α with a simple cell-based assay to evaluate the capacity of the serum sample to induce apoptosis in Jurkat cells. Interlinking of these parameters can be explored to design a minimum invasive diagnostic strategy for cervical cancer (CC).Methods:Sera samples were assessed to induce apoptosis in Jurkat cells through FACS. Serum levels of sCD95 and TNF-α were measured by ELISA. JNK phosphorylation was evaluated in sera incubated Jurkat cells. Data was scrutinized through statistical analysis.Results:Significantly higher serum levels of sCD95 and lower TNF-α levels were observed in CC patients; their sera samples inhibited induction of apoptosis in Jurkat cells through reduced JNK phosphorylation. Statistical analysis linked these three parameters for the early screening of CC.Conclusion:Distinct sera levels of sCD95 & TNF-α in CC patients showed an anti-apoptotic effect, which can be considered for early detection of CC.Key Words: Apoptosis, sCD95, Jurkat Cells, Tumor Necrosis Factor-alpha, Uterine Cervical Neoplasms  相似文献   
55.
In this review, we present our current understanding of peripartum cardiomyopathy (PPCM) based on reports of the incidence, diagnosis and current treatment options. We summarise opinions on whether PPCM is triggered by vascular and/or hormonal causes and examine the influence of comorbidities such as preeclampsia. Two articles published in 2021 strongly support the hypothesis that PPCM may be a familial disease. Using large cohorts of PPCM patients, they summarised the available genomic DNA sequence data that are expressed in human cardiomyocytes. While PPCM is considered a disease predominately affecting the left ventricle, there are data to suggest that some cases also involve right ventricular failure. Finally, we conclude that there is sufficient evidence to warrant an RNAseq investigation and that this would be most informative if performed at the cardiomyocytes level rather than analysing genomic DNA from the peripheral circulation. Given the rarity of PPCM, the combined resources of international human heart tissue biobanks have assembled 30 ventricular tissue samples from PPCM patients, and we are actively seeking to enlarge this patient base by collaborating with human heart tissue banks and research laboratories who would like to join this endeavour.  相似文献   
56.
Plant Ecology - Volatile compounds from leaf litter of invasive alien Ageratina adenophora are known to inhibit growth of native species in sub-tropical Asia, but there is not...  相似文献   
57.
In a bid to characterize the antigens and immunization mechanisms which may be used to produce a protective response against L. donovani, role of lipid associated polysaccharide (LPS) antigen and whole antigen was evaluated. BALB/C mice were immunized with whole or LPS antigen in combination with one of three putative adjuvents (anti CD-2 antibody/FIA/0.85% Saline). LPS antigen emulsified in anti CD-2 antibody was found to induce significant antibodies in mice on day 28 against challenge with lethal dose of L. donovani. Immunoprophylactic properties of LPS and whole antigen was investigated on day 40 through cytokine elicitation (IL-2), MIF) in culture supernatants of spleen cells, but before that MHC-II expressed on macrophage was studied. The LPS antigen in combination with anti CD-2 antibody was found to be most immuno-reactive inducing higher MHC-II expression on macrophages which was associated with substantial rise in the level of MIF and IL-2. It coincided with decline in antibody titre in 100% mice immunized with LPS antigen while Leishmania injected as whole antigen failed to induce specific macrophage and T-cell response with all the above formulations. We surmise from our data that lipid associated polysaccharide antigen linked to anti CD-2 antibody has potential for eliciting protective immunity against Leishmania.  相似文献   
58.
Molecular and phylogenetic characterisation of Cryptosporidium from birds   总被引:4,自引:0,他引:4  
Avian isolates of Cryptosporidium species from different geographic locations were sequenced at two loci, the 18S rRNA gene and the heat shock gene (HSP-70). Phylogenetic analysis of the sequence data provided support for the existence of a new avian species of Cryptosporidium infecting finches and a second species infecting a black duck. The identity of Cryptosporidium baileyi and Cryptosporidium meleagridis as valid species was confirmed. Also, C. baileyi was identified in a number of isolates from the brown quail extending the host range of this species.  相似文献   
59.
Abderrazak, S. B., Oury, B, Lal, A. A., Bosseno, M.-F., Force-Barge, P., Dujardin, J.-P., Fandeur, T., Molez, J.-F., Kjellberg, F., Ayala, F. J., and Tibayrenc, M. 1999. Plasmodium falciparum: Population genetic analysis by multilocus enzyme electrophoresis and other molecular markers. Experimental Parasitology 92, 232-238. The population structure of Plasmodium falciparum, the agent of malignant malaria, is uncertain. We have analyzed multilocus enzyme electrophoresis (MLEE) polymorphisms at 7-12 gene loci in each of four populations (two populations in Burkina Faso, one in Sudan, one in Congo), plus one "cosmopolitan" sample consisting of parasite cultures from 15 distant localities in four different continents. We have also performed random amplified polymorphic DNA analysis (RAPD) and restriction fragment length polymorphism (RFLP) and characterized gene varia tion at four antigen genes in the Congo population. All genetic assays show abundant genetic variability in all populations analyzed. With the isoenzyme assays, strong linkage disequilibrium is apparent in at least two local populations, the Congo population and one population from Burkina Faso, as well as in the cosmopolitan sample, and less definitely in the other Burkina Faso population. However, no linkage disequilibrium is detected in the Congo population with the molecular assays. We failed to detect any nonrandom association between the different kinds of genetic markers; that is, MLEE with RAPD or RFLP, RAPD with RFLP, and so on. Although isoenzyme data show statistical departures from panmictic expectations, these results suggest that in the areas under survey, P. falciparum populations do not undergo predominant clonal evolution and show no clear-cut subdivisions, un like Trypanosoma cruzi, Leishmania sp., and other major parasitic species. We discuss the epidemiological and taxonomical significance of these results.  相似文献   
60.
A hydrocarbon degrading Acinetobacter baumannii S30 strain, isolated from crude oil-contaminated soil, was inserted with the lux gene from the luciferase gene cassette luxCDABE. Soil microcosms were designed to study the degradation efficacy for total petroleum hydrocarbon (TPH) of crude oil by lux-tagged A. baumannii S30 pJES. Bioaugmentation of a TPH-contaminated microcosm with A baumannii S30 pJES showed that TPH levels were reduced from 89.3 to 53.9 g/kg soil in 90 days. Biodegradation of TPH by A baumannii S30 pJES was also monitored in shake flask conditions, which showed a reduction of initial TPH levels by over 50% at the end of 120 h. A lux-PCR-based approach along with the standard dilution plating with selective antibiotics was successfully utilized to monitor the survivability of the lux-tagged strain A. baumannii S30 pJES in soil microcosms and stability of the lux insert in the host strain A. baumannii S30. The selective plating technique indicated the population of A. baumannii S30 pJES to be 6.5+/-0.13 x 10(8) CFU/g at day zero (just after bioaugmentation) and 2.09+/-0.08 x 10(8) CFU/g of soil after 90 days of incubation. lux-PCR confirmed the stability of the insert in all the randomly selected colonies of A. baumannii strains from the antibiotic plates. The lux insert was stable after 50 generations in Luria Bertini broth and storage at -70 degrees C as glycerol stocks for over a year. These results revealed that the lux insert was stable and lux-tagged A. baumannii S30 strain could survive in a TPH-contaminated soil microcosm and could degrade TPH in the soil microcosm conditions. It can be used as an effective marker to monitor the survival of augmented strains at a bioremediation site.  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