全文获取类型
收费全文 | 2357篇 |
免费 | 119篇 |
国内免费 | 11篇 |
专业分类
2487篇 |
出版年
2024年 | 7篇 |
2023年 | 47篇 |
2022年 | 42篇 |
2021年 | 64篇 |
2020年 | 48篇 |
2019年 | 49篇 |
2018年 | 93篇 |
2017年 | 75篇 |
2016年 | 109篇 |
2015年 | 75篇 |
2014年 | 110篇 |
2013年 | 180篇 |
2012年 | 140篇 |
2011年 | 179篇 |
2010年 | 107篇 |
2009年 | 85篇 |
2008年 | 109篇 |
2007年 | 103篇 |
2006年 | 106篇 |
2005年 | 121篇 |
2004年 | 123篇 |
2003年 | 141篇 |
2002年 | 72篇 |
2001年 | 64篇 |
2000年 | 62篇 |
1999年 | 49篇 |
1998年 | 8篇 |
1997年 | 16篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1966年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有2487条查询结果,搜索用时 11 毫秒
61.
The protective effects of spermine (SPM) and putrescine (PUT) against paraquat (PQ), a herbicide in agriculture and oxidative
stress inducer, were investigated in the leaves of maize. Maize leaves were pretreated to SPM and PUT at concentrations of
0.2 and 1 mM and treated with PQ afterwards. Pretreatment with 1 mM of SPM and PUT significantly prevented the losses in chlorophyll
and carotenoid levels induced by PQ. Ascorbic acid content in the leaves pretreated with both polyamines was found to be higher
than those of the leaves pretreated with water. Also, pretreatment with SPM and PUT was determined to have some effects on
the activities of superoxide dismutase (SOD) and peroxidase (POD). 1 mM of SPM increased SOD activity, but PUT has no significant
effect on SOD activity. On the other hand, POD activity was recorded to increase slightly in response to both concentrations
of SPM and 1 mM of PUT. The results showed that such polyamine pretreated plants may become more tolerant to oxidative stress
due to increases in the antioxidative enzymes and antioxidants. 相似文献
62.
Sekendiz B Cuğ M Korkusuz F 《Journal of strength and conditioning research / National Strength & Conditioning Association》2010,24(11):3032-3040
The purpose of this study was to investigate the effects of Swiss-ball core strength training on trunk extensor (abdominal)/flexor (lower back) and lower limb extensor (quadriceps)/flexor (hamstring) muscular strength, abdominal, lower back and leg endurance, flexibility and dynamic balance in sedentary women (n = 21; age = 34 ± 8.09; height = 1.63 ± 6.91 cm; weight = 64 ± 8.69 kg) trained for 45 minutes, 3 d·wk-1 for 12 weeks. Results of multivariate analysis revealed significant difference (p ≤ 0.05) between pre and postmeasures of 60 and 90° s trunk flexion/extension, 60 and 240° s-1 lower limb flexion/extension (Biodex Isokinetic Dynamometer), abdominal endurance (curl-up test), lower back muscular endurance (modified Sorensen test), lower limb endurance (repetitive squat test), lower back flexibility (sit and reach test), and dynamic balance (functional reach test). The results support the fact that Swiss-ball core strength training exercises can be used to provide improvement in the aforementioned measures in sedentary women. In conclusion, this study provides practical implications for sedentary individuals, physiotherapists, strength and conditioning specialists who can benefit from core strength training with Swiss balls. 相似文献
63.
64.
Granulocyte–macrophage colony-stimulating factor (GM-CSF) is a cytokine used in the treatment of serious conditions resulting
from chemotherapy and bone marrow transplantation such as neutropenia and aplastic anemia. Despite these effects, GM-CSF has
a very short biological half-life, and it requires frequent injection during the treatment. Therefore, the cytokine production
is possible in the body with plasmid-encoded GM-CSF (pGM-CSF) coding for cytokine administered to the body. However, the selection
of the proper delivery system for the plasmid is important. In this study, two different delivery systems, encapsulated plasmid
such as fucoidan–chitosan (fucosphere) and chitosan microspheres, were prepared and the particle physicochemical properties
evaluated. Fucospheres and chitosan microspheres size ranges are 151–401 and 376–681 nm. The zeta potential values of the
microspheres were changed between 8.3–17.1 mV (fucosphere) and +21.9–28.9 mV (chitosan microspheres). The encapsulation capacity
of fucospheres changed between 84.2% and 94.7% depending on the chitosan molecular weight used in the formulation. In vitro plasmid DNA release from both delivery systems exhibited slower profiles of approximately 90–140 days. Integrity of released
samples was checked by agarose gel electrophoresis, and any additional band was not seen. All formulations were analyzed kinetically.
The calculated regression coefficients showed a higher r
2 value with zero-order kinetics. In conclusion, the characterizations of the microspheres can be modulated by changing the
formulation variables, and it can be concluded that fucospheres might be a potential carrier system for the controlled delivery
of GM-CSF encoding plasmid DNA. 相似文献
65.
Kadriye Çağlayan Kivilcim Ördek Mona Gazel Eminur Elçi Vahid Roumi Janja Lamovšek Irena Mavrič Pleško 《The Annals of applied biology》2023,183(3):209-219
Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy. 相似文献
66.
Demir Ersin Nedzvetsky Viktor S. Ağca Can Ali Kirici Mahinur 《Neurochemical research》2020,45(10):2385-2397
Neurochemical Research - Diabetes mellitus is a prevalent metabolic disorder associated with multiple complications including neuropathy, memory loss and cognitive decline. Despite a long history... 相似文献
67.
The development, survival and reproduction of the cabbage aphid, Brevicoryne brassicae (L.) were evaluated at three constant temperatures (20, 25 and 30°C) on cabbage, cauliflower, red cabbage, turnip and radish. The development periods of immature stages ranged from 10.7 d at 20°C to 7.60 d at 30°C for red cabbage. Total percentages of survivorship of immature stages varied from 39.40 and 82.50 within the temperature range of 25–30°C on radish. The average progeny per female was 31.15, 28.95 and 23.77 at 20, 25 and 30°C on cabbage. 相似文献
68.
Koçer U Aksoy HM Tiftikcioğlu YO Cöloğlu H Karaaslan O 《Genetic counseling (Geneva, Switzerland)》2001,12(4):341-346
Report of two cases with Van der Woude syndrome: a child and her mother: Congenital pits of the lower lip are rare malformations. They are closely associated with cleft lip (CL), cleft lip/palate (CL/CP) or isolated cleft palate (CP) and if so this condition is known as Van der Woude syndrome, which is inherited in an autosomal dominant fashion with high penetrance. Two individuals, one with lower lip pits and cleft palate and the other with isolated lower lip pit from the same family are described. Autosomal dominant pattern of inheritance was observed in this family and treatment consisted of complete removal of sinus tracts in one patient. Pathological features of sinus tracts consisted of stratified nonkeratinized squamous epithelium and a lamina propria of dense connective tissue. Importance of genetic counseling is emphasized as at least half of gene carriers have some kind of clefting. 相似文献
69.
Y H Gulcan N Duman A Kumral B Sa?olLebe S Kavuk?u D Er?al M Celilo?lu H Ozkan 《Genetic counseling (Geneva, Switzerland)》2001,12(3):263-267
Cerebrohepatorenal malformation is a rare familial disorder characterized by typical renal lesions combined with Dandy-Walker malformation, and congenital hepatic fibrosis. In this case report, a male premie with the diagnosis of cerebrorenal syndrome or so called Goldston syndrome is presented. Besides the rarity of this syndrome, this case is the second reported patient diagnosed prenatally. 相似文献
70.
To evaluate whether bombesin treatment has a facilitatory effect on the healing of chronic gastric ulcer, following the induction of ulcer by serosal application of acetic acid, rats were given bombesin (30 microg/kg/day; subcutaneously) or vehicle three times a day for 7, 14 or 21 days until they were decapitated. Neither food intake nor gastric emptying rate in either vehicle-treated or bombesin-treated groups was not statistically different from control rats. Similarly, ulcer indices and gastric myeloperoxidase (MPO) activities at the first and second weeks of injury were not different among the groups. However, in the 3-week ulcer group, bombesin treatment reduced tissue MPO level significantly back to control levels. Moreover, the analysis of the surface epithelium by scanning electron and light microscopy demonstrated a significant reduction in the severity of ulcers by bombesin treatment. Pretreatment with CCK antagonists (L-364,718 or L365,260; 25 micromol/kg/day) before bombesin treatment showed that neither of the CCK antagonists had a significant effect on the bombesin-mediated healing process, suggesting that CCK receptors are not involved in the action of bombesin. In accordance with the previous studies that show its acute gastroprotective effects, bombesin is also effective in promoting the healing process of chronic gastric ulcer in rats. 相似文献