全文获取类型
收费全文 | 492篇 |
免费 | 65篇 |
专业分类
557篇 |
出版年
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 24篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 27篇 |
2011年 | 27篇 |
2010年 | 24篇 |
2009年 | 9篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 19篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 19篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 9篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1958年 | 7篇 |
1955年 | 3篇 |
1954年 | 5篇 |
1953年 | 5篇 |
1952年 | 4篇 |
排序方式: 共有557条查询结果,搜索用时 15 毫秒
31.
K H Roux J M Kilpatrick J E Volanakis J F Kearney 《Journal of immunology (Baltimore, Md. : 1950)》1983,131(5):2411-2415
C-reactive protein (CRP) was reacted with monoclonal IgG antibody or Fab antibody fragments directed against the phosphocholine- (PC) binding site or a second unrelated site. The resulting immune complexes were viewed by a negative stain immunoelectron microscopy technique. Monoclonal anti-PC-binding site antibody bound to a single epitope on each of the five CRP subunits. The orientation of the PC-binding sites was determined to be slightly medial to one of the planar faces (A-face) of the molecule. The second monoclonal antibody, which was not PC-binding site related, bound to epitopes (one per CRP subunit) that were located slightly lateral to the other planar face (B-face) of the CRP molecule, i.e., opposite of the PC-binding site. Thus, the PC-binding site and the non-PC-binding site are oriented nearly perpendicular but on opposite sides with respect to the plane of the CRP molecule. The functional significance of this configuration is discussed. 相似文献
32.
33.
Md. Ashraful Alam Milan Skalicky Muhammad Rezaul Kabir Md. Monwar Hossain Md. Abdul Hakim Md. Siddikun Nabi Mandal Rabiul Islam Md. Babul Anwar Akbar Hossain Fahmy Hassan Amaal Mohammadein Muhammad Aamir Iqbal Marian Brestic Mohammad Anwar Hossain Khalid Rehman Hakeem Ayman EL Sabagh 《Phyton》2021,90(4):1301-1320
Globally among biotic stresses, diseases like blight, rust and blast constitute prime constraints for reducing wheat
productivity especially in Bangladesh. For sustainable productivity, the development of disease-resistant lines and
high yielding varieties is vital and necessary. This study was conducted using 122 advanced breeding lines of
wheat including 21 varieties developed by Bangladesh Wheat and Maize Research Institute (BAMRI) with aims
to identify genotypes having high yield potential and resistance to leaf blight, leaf rust and blast diseases. These
genotypes were evaluated for resistance against leaf blight and leaf rust at Dinajpur and wheat blast at Jashore
under field condition. Out of 122 genotypes tested, 20 lines were selected as resistant to leaf blight based on
the area under the diseases progress curve (AUDPC) under both irrigated timely sown (ITS) and irrigated late
sown (ILS) conditions. Forty-two genotypes were found completely free from leaf rust infection, 59 genotypes
were identified as resistant, and 13 genotypes were identified as moderately resistant to leaf rust. Eighteen genotypes were immune against wheat blast, 42 genotypes were categorized as resistant, and 26 genotypes were identified as moderately resistant to wheat blast. Molecular data revealed that the 16 genotypes showed a positive 2NS
segment among the 18 immune genotypes selected against wheat blast under field conditions. The genotypes
BAW 1322, BAW 1295, and BAW 1203 can be used as earlier maturing genotypes and the genotypes BAW
1372, BAW 1373, BAW 1297 and BAW 1364 can be used for lodging tolerant due to short plant height. The genotypes WMRI Gom 1, BAW 1349 and BAW 1350 can be selected for bold grain and the genotypes WMRI Gom 1,
BAW 1297, BAW 1377 can be used as high yielder for optimum seeding condition but genotypes BAW 1377
and BAW 1366 can be used for late sown condition. The selected resistant genotypes against specific diseases can be used in the further breeding program to develop wheat varieties having higher disease resistance and
yield potential. 相似文献
34.
M. I. El Gohary A. A. Salama A. A. EL Saeid T. M. El Sayed H. Sh. Kotb 《Cell biochemistry and biophysics》2013,67(3):929-933
The aim of the present work is to evaluate the effect of caffeine, the world’s most popular psychoactive drug, on the electric activity of the rat’s brain that exposed to extremely low-frequency magnetic field (ELF-MF), during 15 days. The obtained results showed that administration of caffeine in a group of rats by dose of 10 mg/kg (equivalent to human daily consumption) caused a reduction in the mean power amplitude of electroencephalogram (EEG) trace for almost all frequency bands especially α (8–12 Hz). It was observed that the influence of caffeine was more evident in motor cortex than in visual cortex. While the exposure of another group to ELF-MF of intensity 0.2 mT during the same period caused an enhancement in the mean power amplitude of most EEG frequency bands; this was more observed in the right hemisphere of the brain than that of the left hemisphere. The administration of caffeine while rats were exposed to ELF-MF, led, after 5 days of exposure, to a great increase in the mean power amplitude of α band at all places of recording electrodes. It may be concluded that caffeine administration was more effective in reducing the hazardous of ELF-MF in motor cortex than in visual cortex. 相似文献
35.
Pedro M. D. Moreno Sylvain Geny Y. Vladimir Pabon Helen Bergquist Eman M. Zaghloul Cristina S. J. Rocha Iulian I. Oprea Burcu Bestas Samir EL Andaloussi Per T. J?rgensen Erik B. Pedersen Karin E. Lundin Rula Zain Jesper Wengel C. I. Edvard Smith 《Nucleic acids research》2013,41(5):3257-3273
In spite of the many developments in synthetic oligonucleotide (ON) chemistry and design, invasion into double-stranded DNA (DSI) under physiological salt and pH conditions remains a challenge. In this work, we provide a new ON tool based on locked nucleic acids (LNAs), designed for strand invasion into duplex DNA (DSI). We thus report on the development of a clamp type of LNA ON—bisLNA—with capacity to bind and invade into supercoiled double-stranded DNA. The bisLNA links a triplex-forming, Hoogsteen-binding, targeting arm with a strand-invading Watson–Crick binding arm. Optimization was carried out by varying the number and location of LNA nucleotides and the length of the triplex-forming versus strand-invading arms. Single-strand regions in target duplex DNA were mapped using chemical probing. By combining design and increase in LNA content, it was possible to achieve a 100-fold increase in potency with 30% DSI at 450 nM using a bisLNA to plasmid ratio of only 21:1. Although this first conceptual report does not address the utility of bisLNA for the targeting of DNA in a chromosomal context, it shows bisLNA as a promising candidate for interfering also with cellular genes. 相似文献
36.
The objective of this study was to elucidate the effect of soybean oil (SbO) and sesame oil (SO) supplemented diets on bone biomarkers changes in OVX (ovariectomized) rats. The current data exhibited significant decrease in BMD (bone mineral density), accompanied with marked depletion in the level of Ca, P and Mg in both serum and bone of OVX rats. Also, serum estrogen, total protein, HDL-C (high density lipoprotein cholesterol), bone NO levels were decreased in OVX rats. However, a significant increase in the level of serum TL (total lipids), TC (total cholesterol), TG (triglycerides), LDL-C (low density lipoprotein cholesterol), VLDL-C (very low density lipoprotein cholesterol), urine minerals (Ca, P, Mg), as well as serum, bone and urine ALP (alkaline phosphatase) and ACP (acid phosphatase) activity were recorded in OVX rats. Further changes were also detected by the increased level of urine hydroxyproline, serum parathyroid hormone and osteocalcin, as well as urea and creatinine level in both serum and urine. On the other hand, when OVX rats were fed on SbO (soy bean oil) (15 % w/w) or SO (sesame oil) (10 % w/w) supplemented diets, the data recorded a significant improvement in all the above mentioned parameters. So, it can be concluded that consumption of SbO or SO supplemented diets might be considered as a functional food for retarding risks of osteoporosis associated with estrogen deficiency in OVX states. 相似文献
37.
38.
39.
HENRY SILVERMAN BABIKER AHMED SAMAR AJEILET SUMAIA AL‐FADIL SUHAIL AL‐AMAD HADIR EL‐DESSOUKY IBRAHIM EL‐GENDY MOHAMED EL‐GUINDI MUSTAFA EL‐NIMEIRI RANA MUZAFFAR AZZA SALEH 《Developing world bioethics》2010,10(2):70-77
To help ensure the ethical conduct of research, many have recommended educational efforts in research ethics to investigators and members of research ethics committees (RECs). One type of education activity involves multi‐day workshops in research ethics. To be effective, such workshops should contain the appropriate content and teaching techniques geared towards the learning styles of the targeted audiences. To ensure consistency in content and quality, we describe the development of a curriculum guide, core competencies and associated learning objectives and activities to help educators organize research ethics workshops in their respective institutions. The curriculum guide is divided into modular units to enable planners to develop workshops of different lengths and choose content materials that match the needs, abilities, and prior experiences of the target audiences. The content material in the curriculum guide is relevant for audiences in the Middle East, because individuals from the Middle East who participated in a Certificate Program in research ethics selected and developed the training materials (e.g., articles, powerpoint slides, case studies, protocols). Also, many of the activities incorporate active‐learning methods, consisting of group work activities analyzing case studies and reviewing protocols. The development of such a workshop training curriculum guide represents a sustainable educational resource to enhance research ethics capacity in the Middle East. 相似文献
40.