全文获取类型
收费全文 | 4560篇 |
免费 | 231篇 |
出版年
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 62篇 |
2020年 | 27篇 |
2019年 | 27篇 |
2018年 | 65篇 |
2017年 | 52篇 |
2016年 | 81篇 |
2015年 | 161篇 |
2014年 | 186篇 |
2013年 | 278篇 |
2012年 | 301篇 |
2011年 | 319篇 |
2010年 | 186篇 |
2009年 | 185篇 |
2008年 | 283篇 |
2007年 | 297篇 |
2006年 | 276篇 |
2005年 | 261篇 |
2004年 | 269篇 |
2003年 | 275篇 |
2002年 | 266篇 |
2001年 | 61篇 |
2000年 | 67篇 |
1999年 | 71篇 |
1998年 | 46篇 |
1997年 | 49篇 |
1996年 | 35篇 |
1995年 | 45篇 |
1994年 | 26篇 |
1993年 | 28篇 |
1992年 | 52篇 |
1991年 | 43篇 |
1990年 | 67篇 |
1989年 | 32篇 |
1988年 | 29篇 |
1987年 | 39篇 |
1986年 | 25篇 |
1985年 | 30篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1977年 | 5篇 |
1975年 | 5篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有4791条查询结果,搜索用时 750 毫秒
971.
Human orosomucoid polymorphism: molecular basis of the three common ORM1 alleles, ORM1*F1, ORM1*F2, and ORM1*S 总被引:3,自引:0,他引:3
I. Yuasa Kazuo Umetsu Ulrike Vogt Hiroaki Nakamura Eiji Nanba Nobuto Tamaki Yoshito Irizawa 《Human genetics》1997,99(3):393-398
The human orosomucoid (ORM) is controlled by two closely linked loci, ORM1 and ORM2, and two tandem genes, AGP1 and AGP2,
encoding the proteins produced by the two loci, have been cloned. In this study the molecular basis of ORM1 polymorphism was
investigated. For the detection of mutations the products of the six exons of each gene, amplified by the polymerase chain
reaction (PCR), were screened by single-strand conformation polymorphism analysis. Subsequently, the exons with an altered
migration pattern were gene-specifically amplified by nested PCR. Sequencing of the gene-specific PCR products showed that
the three common ORM1 alleles result from A→G transitions at the codons for amino acid positions 20 in exon 1 and 156 in exon
5 of the AGP1 gene: ORM1*F1 was characterized by CAG (Gln) and GTG (Val), ORM1*F2, by CAG (Gln) and ATG (Met), and ORM1*S,
by CGG (Arg) and GTG (Val). The phylogenesis of the genes encoding these three ORM1 alleles is discussed.
Received: 5 September 1996 相似文献
972.
Glutamate synthase (GOGAT) is a key enzyme in the assimilation of inorganic nitrogen in photosynthetic organisms. We found that, like higher plants, the facultative heterotrophic cyanobacterium Plectonema boryanum had ferredoxin (Fd)- and NADH-dependent GOGATs. The genes glsF, gltB, and gltD were cloned, and structural analyses and target mutageneses demonstrated that glsF encoded Fd-GOGAT and that gltB and gltD encoded the two subunits of NADH-GOGAT. All three mutants lacking one of the GOGAT genes were able to grow photosynthetically and heterotrophically. However, the Fd-GOGAT mutant exhibited a phenotype of marked nitrogen deficiency when grown under conditions of saturating illumination and CO2 supply. In these conditions the rate of the ammonia uptake from the culture medium was slower in the Fd-GOGAT mutant than in the wild type or in the NADH-GOGAT mutant, but no significant differences were found in the rate of the CO2 fixation-dependent O2 evolution among these strains. Our results suggest that, although both Fd- and NADH-GOGATs were operative in the cells growing in light, the contribution of Fd-GOGAT, which directly utilizes photoreducing power for the catalytic reaction, is essential for balancing photosynthetic nitrogen and carbon assimilation. 相似文献
973.
Tetsuro Muraoka Tadashi Muramatsu Tetsuo Fukunaga Hiroaki Kanehisa 《Journal of applied physiology》2005,99(2):665-669
The purpose of this study was to investigate whether the mechanical properties of the Achilles tendon were correlated to muscle strength in the triceps surae in humans. Twenty-four men and twelve women exerted maximal voluntary isometric plantar flexion (MVIP) torque. The elongation (DeltaX) and strain of the Achilles tendon (epsilon), the proximal part of which is the composite of the gastrocnemius tendon and the soleus aponeurosis, at MVIP were determined from the displacement of the distal myotendinous junction of the medial gastrocnemius using ultrasonography. The Achilles tendon force at MVIP (F) was calculated from the MVIP torque and the Achilles tendon moment arm. There were no significant differences in either the F-DeltaX or F-epsilon relationships between men and women. DeltaX and epsilon were 9.8 +/- 2.6 mm and 5.3 +/- 1.6%, respectively, and were positively correlated to F (r = 0.39, P < 0.05; r = 0.39, P < 0.05), which meant that subjects with greater muscle strength could store more elastic energy in the tendon. The regression y-intercepts for the F-DeltaX (P < 0.01) and F-epsilon (P < 0.05) relationship were significantly positive. These results might indicate that the Achilles tendon was stiffer in subjects with greater muscle strength, which may play a role in reducing the probability of tendon strain injuries. It was suggested that the Achilles tendon of subjects with greater muscle strength did not impair the potential for storing elastic energy in tendons and may be able to deliver the greater force supplied from a stronger muscle more efficiently. Furthermore, the difference in the Achilles tendon mechanical properties between men and women seemed to be correlated to the difference in muscle strength rather than gender. 相似文献
974.
Atsushi Watanabe Hiroaki Uemoto Masahiko Morisa Shin Saitoh Rika Yoshizaki 《Biological Sciences in Space》2004,18(3):142-143
To control nitrogen such as ammonia in a rearing water of aquatic animals, we developed new bioreactor capable of both nitrification and denitrification. It was consisted of gel-plate immobilized microorganisms and a biodegradable plastic plate composed of three kind of poly(lactic acid) as an energy source of denitrification. When batch treatment experiment by the bioreactor was continuously carried out with an artificial rearing water containing ammonia, nitrogen-removal rate of the bioreactor was approximately 3 g-N/d/m2-gel surface and the activity was maintained for over 3 month without additional energy source. Therefore, the bioreactor would be effective to control nitrogen concentration in rearing water of a closed water circulating system for aquatic animals. 相似文献
975.
Hiroaki Kawano Yasuo Suzaki Junko Fukuchi Kaoru Nakasone Fumiyoshi Abe Chiaki Kato Yasuhiko Yoshida Ron Usami Koki Horikoshi 《DNA sequence》2004,15(2):118-122
We have cloned the rpoZ gene, encoding RNA polymerase omega protein, by PCR approach from the deep-sea piezophilic and psychrophilic bacterium, Shewanella violacea strain DSS12. The cloned gene, 285bp in length, was found to encode a protein consisting of 94 amino acid residues with a molecular mass of 10,327 Da. Significant homology was evident comparing the RpoZ protein of S. violacea with that of Shewanella oneidensis (69% identity), Vibrio cholerae (65% identity), Escherichia coli K-12 (64% identity) and Haemophilus influenzae (61% identity). From the Northern blot analysis, S. violacea rpoZ gene was expressed constitutively under pressure conditions of 0.1, 30 and 50MPa. We constructed expression plasmid to overproduce the RpoZ protein and transformed into E. coli JM109 as a host of overproduction. Upon induction, the recombinant protein encoded by plasmid pQrpoZ was overexpressed and purified using Ni2+ affinity column. 相似文献
976.
977.
Peng Li Qing-Li Zhao Paras Jawaid Mati Ur Rehman Hiroaki Sakurai Takashi Kondo 《Cell stress & chaperones》2016,21(5):873-881
KRAS mutant lung cancers have long been considered as untreatable with drugs. Transforming growth factor-β-activated kinase 1 (TAK1) appears to play an anti-apoptotic role in response to multiple stresses and has been reported to be a responsive kinase that regulates cell survival in KRAS-dependent cells. In this study, in order to find a useful approach to treat KRAS mutant lung cancer, we focused on the combined effects of 5Z-7-oxozeaenol, a TAK1 inhibitor, with hyperthermia (HT) in KRAS mutant lung cancer cell line A549. Annexin V-FITC/PI assay, cell cycle analysis, and colony formation assay revealed a significant enhancement in apoptosis induced by HT treatment, when the cells were pre-incubated with 5Z-7-oxozeaenol in a dose-dependent manner. The enhanced apoptosis by 5Z-7-oxozeaenol was accompanied by a significant increase in reactive oxygen species (ROS) generation and loss of mitochondrial membrane potential (MMP). In addition, western blot showed that 5Z-7-oxozeaenol enhanced HT-induced expressions of cleaved caspase-3, cleaved caspase-8, and HSP70 and decreased HT-induced expressions of Bcl-2, p-p38, p-JNK, and LC3. Moreover, 5Z-7-oxozeaenol pre-treatment resulted in a marked elevation of intracellular calcium level which might be associated with endoplasmic reticulum (ER) stress-related pathway. Taken together, our data provides further insights of the mechanism of action of 5Z-7-oxozeaenol and HT treatment, and their potential application as a novel approache to treat patients with KRAS mutant lung cancer. 相似文献
978.
979.
Sachiko Hojo Mikiko Tokiya Masami Mizuki Mikio Miyata Kumiko T. Kanatani Airi Takagi Naomi Tsurikisawa Setsuko Kame Takahiko Katoh Takuya Tsujiuchi Hiroaki Kumano 《Bioelectromagnetics》2016,37(6):353-372
The purpose of the present study was to evaluate the validity and reliability of a Japanese version of an electromagnetic hypersensitivity (EHS) questionnaire, originally developed by Eltiti et al. in the United Kingdom. Using this Japanese EHS questionnaire, surveys were conducted on 1306 controls and 127 self‐selected EHS subjects in Japan. Principal component analysis of controls revealed eight principal symptom groups, namely, nervous, skin‐related, head‐related, auditory and vestibular, musculoskeletal, allergy‐related, sensory, and heart/chest‐related. The reliability of the Japanese EHS questionnaire was confirmed by high to moderate intraclass correlation coefficients in a test–retest analysis, and high Cronbach's α coefficients (0.853–0.953) from each subscale. A comparison of scores of each subscale between self‐selected EHS subjects and age‐ and sex‐matched controls using bivariate logistic regression analysis, Mann–Whitney U‐ and χ2 tests, verified the validity of the questionnaire. This study demonstrated that the Japanese EHS questionnaire is reliable and valid, and can be used for surveillance of EHS individuals in Japan. Furthermore, based on multiple logistic regression and receiver operating characteristic analyses, we propose specific preliminary criteria for screening EHS individuals in Japan. Bioelectromagnetics. 37:353–372, 2016. © 2016 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc. 相似文献
980.