全文获取类型
收费全文 | 2606篇 |
免费 | 130篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 37篇 |
2021年 | 71篇 |
2020年 | 49篇 |
2019年 | 76篇 |
2018年 | 105篇 |
2017年 | 75篇 |
2016年 | 126篇 |
2015年 | 157篇 |
2014年 | 159篇 |
2013年 | 218篇 |
2012年 | 242篇 |
2011年 | 227篇 |
2010年 | 140篇 |
2009年 | 98篇 |
2008年 | 175篇 |
2007年 | 179篇 |
2006年 | 155篇 |
2005年 | 106篇 |
2004年 | 80篇 |
2003年 | 101篇 |
2002年 | 68篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有2736条查询结果,搜索用时 15 毫秒
121.
Kiraga-Motoszko K Stepinski J Niedzwiecka A Jemielity J Wszelaka-Rylik M Stolarski R Zielenkiewicz W Darzynkiewicz E 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):1711-1714
Measurements of interaction of 7-methyl-GTP eIF4E from S. cerevisiae were performed by means of two methods: Isothermal Titration Calorimetry (ITC) and fluorescence titration. The equilibrium association constants (Kas) derived from the two methods show significantly different affinity of yeast eIF4E for the mRNA 5' cap than those of the murine and human proteins. The observed differences in the Kas values and the enthalpy changes of the association (deltaH(o)) suggest some dissimilarity in the mode of binding and stabilization of cap in the complexes with eIF4E from various sources. 相似文献
122.
Grzyb K Rychłowski M Biegniewska A Skorkowski EF 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2003,134(2):207-213
Creatine kinase (CK, ATP creatine phosphotransferase, EC 2.7.3.2) is an enzyme participating in ATP regeneration, which is the primary source of energy in living organisms. We demonstrated that CK from herring spermatozoa has high activity ( approximately 452 micromol/min/g of fresh semen) and has a different electrophoretic mobility from isoenzymes present in skeletal muscle. In our study, we investigated toxic effect of tributyltin (TBT) on herring spermatozoa using a specific sperm viability kit to observe live and dead sperm cells with a confocal microscope. Treatment of herring spermatozoa with TBT caused a time-dependent decrease of viability: 35% nonviable cells with 5 microM TBT and more than 90% nonviable cells with 10 microM TBT after 6 h exposure. We also monitored CK release from damaged spermatozoa into surrounding medium containing different concentrations of TBT. The higher concentration of TBT was used the more CK release from spermatozoa was observed. We suggest that CK could be a good biomarker of sperm cell membranes degradation in the case when lactate dehydrogenase release from permeabilized cells is not possible for rapid determination of the effect of TBT. 相似文献
123.
124.
Komorowski S Szczepanska K Maleszewski M 《The International journal of developmental biology》2003,47(1):65-69
Fertilization of a mouse egg results in modification of the cytoplasmatic membrane (oolemma) which makes fusion with additional sperm impossible. CD9 is a transmembrane protein reported to be responsible for gamete fusion. Since the molecular mechanism of zygote membrane modification after fertilization remains unknown, we were interested to check whether lack of CD9 is the reason for non-penetrability of zona-free zygotes. We wanted also to determine the effect of different methods of zona pellucida removal on the presence of CD9 on the surface of unfertilized eggs and their ability to be fertilized afterwards. We demonstrated that CD9 is present on the surface of both zygotes and parthenogenotes. We showed also that the treatment of eggs with pronase completely removes CD9 from the membrane of eggs making them infertile. Eggs treated with chymotrypsin and acid Tyrode still posses CD9 on their surface and remain fertile. The results of our experiments indicate that modification of the zygote oolemma does not involve a lack of CD9. We cannot exclude however, that the amount of CD9 decreases after fertilization. In addition, our studies indicate that the previously reported infertility of eggs treated with different proteases may result from the decrease or removal of CD9 and probably other proteins responsible for gamete fusion from the surface of eggs. 相似文献
125.
Milowska K Gabryelak T Dudala J Labieniec M Slobozhanina E 《Zeitschrift für Naturforschung. C, Journal of biosciences》2003,58(11-12):867-872
Many chlorinated phenols and their derivatives are used extensively as insecticides, fungicides and herbicides by industrial and agricultural users throughout the world. Among these substances, pentachlorophenol (PCP) is a broad-spectrum biocide, which is still used as a wood preservative. In this paper, the digestive gland cells were used to assess the effect of PCP in the range of concentrations 3.75-75 microM (0.01-0.2 ppm) on oxidative DNA damage, fluidity changes and peroxidation activity in the plasma membrane. The toxic property of PCP on DNA strand breakage was studied using the comet assay. The results showed that pentachlorophenol in the range of 37.5-75 microM contributed to these lesions. To demonstrate the changes in the fluidity of plasma membrane we used the spectrofluorimetric method using two fluorescence probes: 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 12-(9-anthroyloxy) stearic acid (12-AS). It was shown that PC did not influence the surface of plasma membrane but contributed to the increase in the fluidity of the internal region of the lipid bilayer in the range of concentrations 18.75-75 microM (0.05-0.2 ppm). We also examined the effect of PCP on the lipid peroxidation. To imply its peroxidation properties the spectrophotometry method was used to measure the level of malondialdehyde (MDA), one of the endpoints of the peroxidation of polyunsaturated fatty acids. The obtained results showed that PCP in the used doses did not initiate the formation of lipid peroxides. Thus, our investigation indicates that PCP can behave as a prooxidant agent but its action depends on the used doses and parameters chosen for the research. 相似文献
126.
Total aluminum, chromium, copper, iron, manganese, and nickel were determined in black tea, green tea, Hibiscus sabdariffa, and Ilex paraguariensis (mate) by electrothermal atomic absorption spectrometry after nitric/perchloric acid digestion. In each case, one ground
sample of commercially available leafy material was prepared and three 0.5-g subsamples were run in parallel. The infusions
were also analyzed and the percentage of each element leached into the liquor was evaluated. The obtained results indicated
that hibiscus and mate contained lower levels of aluminum (272±19 μg/g and 369±22 μg/g, respectively) as referred to black
tea (759±31 μg/g) or green tea (919±29 μg/g) and suggested that mate drinking could be a good dietary source of essential
micronutrient manganese (total content 2223±110 μg/g, 48.1% leached to the infusion). It was also found that the infusion
of hibiscus could supply greater amounts of iron (111±5 μg/g total, 40.5% leached) and copper (5.9±0.3 μg/g total, 93.4% leached)
as compared to other infusions. Moreover, it was found that the percentage of element leached to the infusion was strongly
related to the tannins content in the beverage (correlation coefficients >0.82 with the exception for nickel); for lower tannins
level, better leaching was observed. 相似文献
127.
To fully realize its potential, distributed supercomputing requires abstractions and environments facilitating development
of efficient applications. In this paper we present PARDIS, a system which addresses this demand by providing support for
interoperability of PARallel DIStributed applications. The design of PARDIS is based on the Common Object Request Broker Architecture
(CORBA). Like CORBA, it provides interoperability between heterogeneous components by specifying their interfaces in a meta-language,
the CORBA IDL, which can be translated into the language of interacting components. However, PARDIS extends the CORBA object
model by introducing SPMD objects representing data-parallel computations. This extension allows us to build interactions
involving data-parallel components, which exchange distributed data structures whose definitions are captured by distributed
sequences. We present microbenchmark results which evaluate the performance potential of SPMD objects for data structures
of diverse complexity and different network configurations. Based on these results, we conclude that while encapsulating the
existence of multiple interactions SPMD objects also allow their efficient utilization, and therefore constitute a useful
abstraction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
128.
Katarzyna Danis-Wlodarczyk Tomasz Olszak Michal Arabski Slawomir Wasik Grazyna Majkowska-Skrobek Daria Augustyniak Grzegorz Gula Yves Briers Ho Bin Jang Dieter Vandenheuvel Katarzyna Anna Duda Rob Lavigne Zuzanna Drulis-Kawa 《PloS one》2015,10(5)
We here describe two novel lytic phages, KT28 and KTN6, infecting Pseudomonas aeruginosa, isolated from a sewage sample from an irrigated field near Wroclaw, in Poland. Both viruses show characteristic features of Pbunalikevirus genus within the Myoviridae family with respect to shape and size of head/tail, as well as LPS host receptor recognition. Genome analysis confirmed the similarity to other PB1-related phages, ranging between 48 and 96%. Pseudomonas phage KT28 has a genome size of 66,381 bp and KTN6 of 65,994 bp. The latent period, burst size, stability and host range was determined for both viruses under standard laboratory conditions. Biofilm eradication efficacy was tested on peg-lid plate assay and PET membrane surface. Significant reduction of colony forming units was observed (70-90%) in 24 h to 72 h old Pseudomonas aeruginosa PAO1 biofilm cultures for both phages. Furthermore, a pyocyanin and pyoverdin reduction tests reveal that tested phages lowers the amount of both secreted dyes in 48-72 h old biofilms. Diffusion and goniometry experiments revealed the increase of diffusion rate through the biofilm matrix after phage application. These characteristics indicate these phages could be used to prevent Pseudomonas aeruginosa infections and biofilm formation. It was also shown, that PB1-related phage treatment of biofilm caused the emergence of stable phage-resistant mutants growing as small colony variants. 相似文献
129.
Wies?awa Klimek-Piotrowska Mateusz Koziej Mateusz K. Ho?da Katarzyna Pi?tek Karolina Wszo?ek Anna Tyszka Elizabeth Kmiotek Mateusz Pliczko Aleksandra ?liwińska Klaudia Krauss Marcin Miszczyk Jerzy Walocha 《PloS one》2015,10(3)