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   33922篇
  免费   2740篇
  国内免费   2846篇
  2024年   61篇
  2023年   420篇
  2022年   1042篇
  2021年   1832篇
  2020年   1317篇
  2019年   1579篇
  2018年   1445篇
  2017年   1089篇
  2016年   1505篇
  2015年   2174篇
  2014年   2534篇
  2013年   2694篇
  2012年   3176篇
  2011年   2735篇
  2010年   1694篇
  2009年   1535篇
  2008年   1726篇
  2007年   1429篇
  2006年   1300篇
  2005年   1104篇
  2004年   902篇
  2003年   850篇
  2002年   749篇
  2001年   609篇
  2000年   535篇
  1999年   538篇
  1998年   330篇
  1997年   325篇
  1996年   306篇
  1995年   270篇
  1994年   230篇
  1993年   192篇
  1992年   227篇
  1991年   183篇
  1990年   173篇
  1989年   119篇
  1988年   104篇
  1987年   92篇
  1986年   75篇
  1985年   76篇
  1984年   49篇
  1983年   40篇
  1982年   26篇
  1981年   11篇
  1980年   14篇
  1979年   17篇
  1978年   7篇
  1977年   13篇
  1976年   9篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
911.
Guo  Wenfang  Li  Gangqiang  Wang  Nan  Yang  Caifeng  Zhao  Yanan  Peng  Huakang  Liu  Dehu  Chen  Sanfeng 《Plant molecular biology》2020,102(4-5):553-567
Plant Molecular Biology - Overexpression of K2-NhaD in transgenic cotton resulted in phenotypes with strong salinity and drought tolerance in greenhouse and field experiments, increased expression...  相似文献   
912.
Biological Trace Element Research - Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus, presented as a major teratogenic cause worldwide. This study discussed...  相似文献   
913.
Radix Paeoniae Alba is widely used in Chinese traditional medicine to treat various diseases such as gastrointestinal disorders, immunomodulatory, cancer, and other diseases. In this paper, a novel acidic polysaccharide RPAPS purified from Radix Paeoniae Alba was evaluated for its structural features and potential of immunomodulatory and antioxidant activities. RPAPS (molecular weight: 1.0× 105 Da) was mainly composed of α-(1 → 4)-Glcp, α-Arap, α-Galp, α-Rhap, β-D-Glcp, α-(1 → 6)-linked Glcp and GalA. Immunological tests indicated that RPAPS could improve RAW264.7 phagocytic activity and LPS-induced splenocyte proliferation. For antioxidant activities, RPAPS showed reducing power and DPPH scavenging activity in dose dependent. Moreover, RPAPS could significantly protect the PC12 cells from H2O2 damage. These data implied polysaccharides RPAPS had the potential to be novel natural antioxidative and immunopotentiating agents for using in functional foods or medicine.  相似文献   
914.
Huang  Haiyue  Liu  Su  Du  Jiayan  Lin  Jianghui  Liang  Quntao  Liu  Shutao  Wei  Zheng 《Glycoconjugate journal》2020,37(2):201-207
Glycoconjugate Journal - Colla corii asini (CCA) made from donkey-hide has been widely used as a traditional animal-based Chinese medicine. Chondroitin sulfate (CS), dermatan sulfate (DS) and...  相似文献   
915.
Beiging of white adipose tissue (WAT) has beneficial effects on metabolism. Although it is known that beige adipocytes are active in lipid catabolism and thermogenesis, how they are regulated deserves more explorations. In this study, we demonstrate that stearoyl-CoA desaturase 1 (SCD1) in subcutaneous WAT (scWAT) responded to cold stimulation and was able to promote mobilization of triacylglycerol [TAG (triglyceride)]. In vitro studies showed that SCD1 promoted lipolysis in C3H10T1/2 white adipocytes. The lipolytic effect was contributed by one of SCD1’s products, oleic acid (OA). OA upregulated adipose TAG lipase and hormone-sensitive lipase expression. When SCD1 was overexpressed in the scWAT of mice, lipolysis was enhanced, and oxygen consumption and heat generation were increased. These effects were also demonstrated by the SCD1 knockdown experiments in mice. In conclusion, our study suggests that SCD1, known as an enzyme for lipid synthesis, plays a role in upregulating lipid mobilization through its desaturation product, OA.  相似文献   
916.
917.
Vertical farming using light-emitting diode offers potential for the early production phase (few weeks) of young ornamental plants. However, once transferred to the greenhouse, the photosynthetic acclimation of these young plants might depend on this initial light regime. To obtain insight about this acclimatization, Chrysanthemum (sun species) and Spathiphyllum (shade species) were preconditioned in growth chambers for 4 weeks under four light qualities: blue (B), red (R), red/blue (RB, 60% R) and white (W) at 100 μmol m−2 s−1. Monochromatic light (R and B) limited leaf development of both species, which resulted in a lower leaf mass per area when compared to multispectral light (RB for Chrysanthemum, RB and W for Spathiphyllum). R-developed leaves had a lower photosynthetic efficiency in both species. After the light quality pretreatment, plants were transferred to the greenhouse with high-intensity natural light conditions. On the first day of transfer, R and B preconditioned leaves of both species had an inhibited photosynthesis. After 1 week in natural light condition, rapid light curve parameters of Chrysanthemum leaves that developed under B acclimated to sunlight had a similar level than RB-developed leaves unlike R-leaves. Spathiphyllum leaves showed a decrease in maximum electron transport rate and this was most pronounced for the R pretreatment. After 1 month, R-preconditioned Chrysanthemum had the lowest dry mass, while no effects on the dry weight of Spathiphyllum with respect to the pretreatments were observed. Light quality during preconditioning affected the leaf ability to acclimate to natural high light intensities in greenhouse environment.  相似文献   
918.
In order to study how exogenous hormones in C. lanceolata (gymnosperm) regulate somatic embryogenesis, we measured the endogenous phytohormones of two genotypes with different somatic embryogenesis efficiency and found that an increase in endogenous concentrations of IAA and ABA may be correlated to more efficient somatic embryogenesis. By applying exogenous spermidine, we found that exogenous hormones may affect somatic embryogenesis efficiency through affecting the endogenous phytohormone content. Based on these results, further studies can be conducted whereby the concentration of exogenous hormones or the levels of endogenous phytohormones by molecular methods are regulated to promote somatic embryogenesis. Our research may benefit the long-term economic output of the forestry industry and lays the foundation to studying the molecular mechanism that controls somatic embryogenesis efficiency.  相似文献   
919.
Rice blast disease is one of the most devastating diseases of rice (Oryza sativa L.) caused by the fungus Magnaporthe oryzae (M. oryzae), and neck blast is the most destructive phase of this illness. The underlying molecular mechanisms of rice blast resistance are not well known. Thus, we collected 150 rice varieties from different ecotypes in China and assessed the rice blast resistances under the natural conditions that favoured disease development in Jining, Shandong Province, China in 2017. Results showed that 92 (61.3%) and 58 (38.7%) rice varieties were resistant and susceptible to M. oryzae, respectively. Among the 150 rice varieties screened for the presence of 13 major blast resistance (R) genes against M. oryzae by using functional markers, 147 contained one to eight R genes. The relationship between R genes and disease response was discussed by analysing the phenotype and genotype of functional markers. The results showed that the rice blast resistance gene Pita was significantly correlated with rice blast resistance. Our results provided a basis for the further understanding of the distribution of 13 major R genes of rice blast in the germplasm resources of the tested rice varieties, and were meaningful for rice disease resistance breeding.  相似文献   
920.
Activin A belongs to the superfamily of transforming growth factor-β and plays an important role in hormone regulation and tissue development. However, few research studies have been conducted on the effect of activin A on feeding organs in fish. In this study, the zebrafish (Danio rerio) larvae were treated with 1 ng ml–1 activin A for 8 days continuously. The haematoxylin and eosin (H&E) staining section results revealed that the transverse inner diameter of the pharynx and oesophagus significantly increased on the third and eighth days after treatment compared with the control group (P < 0.05). On the eighth day, the cross-sectional area of the pharyngeal muscle increased by 8638 μm2 compared to the control group (P < 0.05). The RNA in situ hybridization results also showed that the expression of skeletal muscle-specific genes (myog and myod) was significantly increased in pharyngeal muscle on the eighth day. Furthermore, the qRT-PCR results showed the expression of gh gene was significantly increased on the eighth day (P < 0.05). At the same time, more larvae in activin A group were able to feed larger brine shrimp (Artemia) than in the control group on the eighth day. In conclusion, activin A could affect feeding by promoting the inner diameter and muscle development of the pharynx and oesophagus in zebrafish larvae. This study is the first to report that the development of the pharynx and oesophagus can directly affect food intake in fish larvae, which provides a theoretical basis for the study of food intake of fish at an early stage.  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