全文获取类型
收费全文 | 759篇 |
免费 | 70篇 |
国内免费 | 2篇 |
专业分类
831篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2016年 | 16篇 |
2015年 | 28篇 |
2014年 | 41篇 |
2013年 | 58篇 |
2012年 | 71篇 |
2011年 | 78篇 |
2010年 | 40篇 |
2009年 | 32篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 69篇 |
2005年 | 74篇 |
2004年 | 31篇 |
2003年 | 18篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有831条查询结果,搜索用时 15 毫秒
61.
Ruehland C Reichel C Neugebauer M Strich S Bertling WM Reiser CO Hess J 《Biotechnology journal》2006,1(6):625-632
This paper describes a novel antibody-based livestock movement control tool and method of meat allocation, both in livestock husbandry as well as during the meat-processing chain. Immuno Track fulfills diverse prerequisites and meets regulatory demands which are substantial for a successful monitoring technology: (i) the induction of long-lasting antibody responses detectable onsite throughout the whole mast period of pigs, (ii) a single immunization injection with protein derivatives is sufficient to evoke a strong epitope-specific antibody response, and (iii) the complete degradation of the protein markers after the antibody response has been triggered in meatproducing animals such as cattle or pigs. There are diverse fields of application for the Immuno-Track marker technology, such as in quality meat programs, as compliance markers for animal vaccines or as a tool for verification of origin. Combination of this monitoring technology with the husbandry and identification databases for cattle and pigs within the European Community will lead to greater transparency in meat production, thereby regaining consumers' trust in concomitant structures of the meat-producing industry. 相似文献
62.
Juergen Geist 《Hydrobiologia》2010,644(1):69-88
Freshwater pearl mussels (Margartifera margaritifera L.) are among the most critically threatened freshwater bivalves worldwide. The pearl mussel simultaneously fulfils criteria
of indicator, flagship, keystone and umbrella species and can thus be considered an ideal target species for the process conservation
of aquatic ecosystem functioning. The development of conservation strategies for freshwater pearl mussels and for other bivalve
species faces many challenges, including the selection of priority populations for conservation and strategic decisions on
habitat restoration and/or captive breeding. This article summarises the current information about the species’ systematics
and phylogeny, its distribution and status as well as about its life history strategy and genetic population structure. Based
on this information, integrative conservation strategies for freshwater mollusc species which combine genetic and ecological
information are discussed. Holistic conservation strategies for pearl mussels require the integration of Conservation Genetics
and Conservation Ecology actions at various spatial scales, from the individual and population level to global biodiversity
conservation strategies. The availability of high resolution genetic markers for the species and the knowledge of the critical
stages in the life cycle, particularly of the most sensitive post-parasitic phase, are important prerequisites for conservation.
Effective adaptive conservation management also requires an evaluation of previous actions and management decisions. As with
other freshwater bivalves, an integrative conservation approach that identifies and sustains ecological processes and evolutionary
lineages is urgently needed to protect and manage freshwater pearl mussel diversity. Such research is important for the conservation
of free-living populations, as well as for artificial culturing and breeding techniques, which have recently been or which
are currently being established for freshwater pearl mussels in several countries. 相似文献
63.
64.
Zhao W Weber C Zhang CL Romanek CS King GM Mills G Sokolova T Wiegel J 《Extremophiles : life under extreme conditions》2006,10(4):337-345
A novel thermophilic, alkali-tolerant, and CO-tolerant strain JW/WZ-YB58T was isolated from green mat samples obtained from the Zarvarzin II hot spring in the Uzon Caldera, Kamchatka (Far East Russia). Cells were Gram-type and Gram stain-positive, strictly aerobic, 0.7–0.8 μm in width and 5.5–12 μm in length and produced terminal spherical spores of 1.2–1.6 μm in diameter with the mother cell swelling around 2 μm in diameter (drumstick-type morphology). Cells grew optimally at pH25°C 8.2–8.4 and temperature 50–52°C and tolerated maximally 6% (w/v) NaCl. They were strict heterotrophs and could not use either CO or CO2 (both with or without H2) as sole carbon source, but tolerated up to 90% (v/v) CO in the headspace. The isolate grew on various complex substrates such as yeast extract, on carbohydrates, and organic acids, which included starch, d-galactose, d-mannose, glutamate, fumarate and acetate. Catalase reaction was negative. The membrane polar lipids were dominated by branched saturated fatty acids, which included iso-15:0 (24.5%), anteiso-15:0 (18.3%), iso-16:0 (9.9%), iso-17:0 (17.5%) and anteiso-17:0 (9.7%) as major constituents. The DNA G+C content of the strain is 45 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain JW/WZ-YB58T is distantly (<93% similarity) related to members of Bacillaceae. On the basis of 16S rRNA gene sequence, physiological and phenotypic characteristics, the isolate JW/WZ-YB58T (ATCC BAA-1258; DSM 17740) is proposed to be the type strain for the type species of the new taxa within the family Bacillaceae, Thermalkalibacillus uzoniensis gen. nov. sp. nov. The Genbank accession number for the 16S rRNA gene sequence is DQ221694.The Genbank accession number for the 16S rRNA gene sequence of strain JW/WZ-YB58T is DQ221694. 相似文献
65.
Walker K Pakhomova ON Kolb J Schoenbach KS Stuck BE Murphy MR Pakhomov AG 《Bioelectromagnetics》2006,27(3):221-225
The study explored the effect of ambient oxygen on mammalian cell survival after exposure to 10 ns duration, high voltage electrical pulses (nsEP, 80-90 or 120-130 kV/cm; 200-400 pulses per exposure). Cell samples were equilibrated with pure nitrogen, atmospheric air, or pure oxygen prior to the nsEP treatment and were returned to the incubator (air + 5% CO2) shortly after the exposure. The experiments established that survival of hypoxic Jurkat and U937 cells exceeded that of air-equilibrated controls about twofold (P < .01). Conversely, saturation of the medium with oxygen prior to exposure decreased Jurkat cell survival about 1.5 times, P < .01. Attenuation of the cytotoxic effect under hypoxic conditions resembled a well-known effect of oxygen on cell killing by sparsely ionizing radiations and may be indicative of the similarity of underlying cell damage mechanisms. 相似文献
66.
Modeling and experimental studies have shown that pulsed electric fields of nanosecond duration and megavolt per meter amplitude affect subcellular structures but do not lead to the formation of large pores in the outer membrane. This "intracellular electromanipulation" requires the use of pulse generators which provide extremely high power but low energy pulses. In this study, we describe the concept of the required pulsed power sources, their design, operation, and the necessary diagnostics. Two types of pulse generators based on the Blumlein line principle have been developed and are described here. One system is designed to treat a large number of cells in cuvettes holding volumes from 0.1 to 0.8 ml. Pulses of up to 40 kV amplitude, with a duration of 10 ns and a rise time close to 1 ns can be applied to the cuvette. For an electrode gap of 1 mm this voltage corresponds to an average electric field of 40 MV/m. The second system allows for real time observation of individual cells under a microscope. It generates pulses of 10-300 ns duration with a rise time of 3.5 ns and voltage amplitudes up to 1 kV. Connected to a microreactor with an electrode gap of 100 microm, electric fields up to 10 MV/m are applied. 相似文献
67.
This paper discusses translocation features of the 20S proteasome in order to explain typical proteasome length distributions.
We assume that the protein transport depends significantly on the fragment length with some optimal length which is transported
most efficiently. By means of a simple one-channel model, we show that this hypothesis can explain both the one- and the three-peak
length distributions found in experiments. A possible mechanism of such translocation is provided by so-called fluctuation-driven
transport. 相似文献
68.
Nuccitelli R Pliquett U Chen X Ford W James Swanson R Beebe SJ Kolb JF Schoenbach KH 《Biochemical and biophysical research communications》2006,343(2):351-360
We have discovered a new, drug-free therapy for treating solid skin tumors. Pulsed electric fields greater than 20 kV/cm with rise times of 30 ns and durations of 300 ns penetrate into the interior of tumor cells and cause tumor cell nuclei to rapidly shrink and tumor blood flow to stop. Melanomas shrink by 90% within two weeks following a cumulative field exposure time of 120 micros. A second treatment at this time can result in complete remission. This new technique provides a highly localized targeting of tumor cells with only minor effects on overlying skin. Each pulse deposits 0.2 J and 100 pulses increase the temperature of the treated region by only 3 degrees C, ten degrees lower than the minimum temperature for hyperthermia effects. 相似文献
69.
The formation of chloro- and bromohydrins from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine following incubation with myeloperoxidase or eosinophil peroxidase in the presence of hydrogen peroxide, chloride and/or bromide was analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. These products were only formed below a certain pH threshold value, that increased with increasing halide concentration. Thermodynamic considerations on halide and pH dependencies of reduction potentials of all redox couples showed that the formation of a given reactive halide species in halide oxidation coupled with the reduction of compound I of heme peroxidases is only possible below a certain pH threshold that depends on halide concentration. The comparison of experimentally derived and calculated data revealed that Cl(2), Br(2), or BrCl will primarily be formed by the myeloperoxidase-H(2)O(2)-halide system. However, the eosinophil peroxidase-H(2)O(2)-halide system forms directly HOCl and HOBr. 相似文献
70.
Schreiber A Shulhevich Y Geraci S Hesser J Stsepankou D Neudecker S Koenig S Heinrich R Hoecklin F Pill J Friedemann J Schweda F Gretz N Schock-Kusch D 《American journal of physiology. Renal physiology》2012,303(5):F783-F788
Determination of glomerular filtration rate (GFR) in conscious mice is cumbersome for the experimenter and stressful for the animals. Here we report on a simple new technique allowing the transcutaneous measurement of GFR in conscious mice. This approach extends our previously developed technique for rats to mice. The technique relies on a miniaturized device equipped with an internal memory that permits the transcutaneous measurement of the elimination kinetics of the fluorescent renal marker FITC-sinistrin. This device is described and validated compared with FITC-sinistrin plasma clearance in healthy, unilaterally nephrectomized and pcy mice. In summary, we describe a technique allowing the measurement of renal function in freely moving mice independent of blood or urine sampling as well as of laboratory assays. 相似文献