全文获取类型
收费全文 | 1812篇 |
免费 | 168篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 39篇 |
2020年 | 21篇 |
2019年 | 28篇 |
2018年 | 18篇 |
2017年 | 34篇 |
2016年 | 54篇 |
2015年 | 77篇 |
2014年 | 92篇 |
2013年 | 105篇 |
2012年 | 122篇 |
2011年 | 120篇 |
2010年 | 73篇 |
2009年 | 63篇 |
2008年 | 77篇 |
2007年 | 90篇 |
2006年 | 86篇 |
2005年 | 79篇 |
2004年 | 81篇 |
2003年 | 78篇 |
2002年 | 74篇 |
2001年 | 45篇 |
2000年 | 38篇 |
1999年 | 42篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 27篇 |
1989年 | 23篇 |
1988年 | 27篇 |
1987年 | 17篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1975年 | 10篇 |
1972年 | 7篇 |
1966年 | 6篇 |
排序方式: 共有1980条查询结果,搜索用时 500 毫秒
41.
Yaoyu Ren Timo Danner Alexandra Moy Martin Finsterbusch Tanner Hamann Jan Dippell Till Fuchs Marius Müller Ricky Hoft André Weber Larry A. Curtiss Peter Zapol Matthew Klenk Anh T. Ngo Pallab Barai Brandon C. Wood Rongpei Shi Liwen F. Wan Tae Wook Heo Martin Engels Jagjit Nanda Felix H. Richter Arnulf Latz Venkat Srinivasan Jürgen Janek Jeff Sakamoto Eric D. Wachsman Dina Fattakhova-Rohlfing 《Liver Transplantation》2023,13(1):2201939
The garnet-type phase Li7La3Zr2O12 (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid-state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all-solid-state LLZO-based battery that delivers safety, durability, and pack-level performance characteristics that are unobtainable with state-of-the-art Li-ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo- and heteroionic interfaces in a pure oxide-based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces during processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO-based SSBs. 相似文献
42.
Effects of bovine colostrum supplementation on serum IGF-I, IgG, hormone, and saliva IgA during training 总被引:2,自引:0,他引:2
Mero Antti; Miikkulainen Heidi; Riski Jarmo; Pakkanen Raimo; Aalto Jouni; Takala Timo 《Journal of applied physiology》1997,83(4):1144-1151
Mero, Antti, Heidi Miikkulainen, Jarmo Riski, RaimoPakkanen, Jouni Aalto, and Timo Takala. Effects of bovinecolostrum supplementation on serum IGF-I, IgG, hormone, and saliva IgAduring training. J. Appl. Physiol.83(4): 1144-1151, 1997.The purpose of this study was to examinethe effects of bovine colostrum supplementation (Bioenervi) on seruminsulin-like growth factor I (IGF-I), immunoglobulin G, hormone, andamino acid and saliva immunoglobulin A concentrations during a strengthand speed training period. Nine male sprinters and jumpersunderwent three randomized experimental training treatments of 8 daysseparated by 13 days. The only difference in the treatments was thedrink of 125 ml consumed per day. Posttraining increases were noticedfor serum IGF-I in the 25-ml Bioenervi treatment (125 ml contained 25 ml Bioenervi) and especially in the 125-ml Bioenervi treatment (125 mlcontained 125 ml Bioenervi) compared with the placebo (normal milkwhey) treatment (P < 0.05). The change in IGF-I concentration during the 8-day periods correlated positively with the change in insulin concentration during the sameperiods with 25-ml Bioenervi treatment(r = 0.68;P = 0.045) and with 125-ml Bioenervitreatment (r = 0.69;P = 0.038). Serum immunoglobulin G,hormone, and amino acid and saliva immunoglobulin A responses weresimilar during the three treatments. It appears that a bovine colostrumsupplement (Bioenervi) may increase serum IGF-I concentration inathletes during strength and speed training. 相似文献
43.
The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 °C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed. 相似文献
44.
Louis M. Kunkel Paul G. Heltne Digamber S. Borgaonkar 《International journal of primatology》1980,1(3):223-232
Karyotypes are reported from 21 spider monkeys distributed among five taxa of the genus Ateles.G- and C- banding techniques revealed variations between taxa. Two variants were discovered for chromosome 5, for chromosome
7, and for the Y chromosome. Four forms of chromosome 6 were seen. The variations are all probably pericentric inversions.
One individual was heteromorphic at position 6. The data are compared with prebanding reports of Ateleschromosomes and reports of five animals studied with banding techniques. The variation in Ateleschromosomes is similar in degree to that found in other ceboid genera. The variants may be related to forest refugia formed
during the Plio-Pleistocene. Karyotyping of many New World primates is required to ensure a homogeneous experimental group. 相似文献
45.
46.
Kalevi Kurkijrvi Raimo Raunio Timo Korpela 《International journal of biological macromolecules》1981,3(6):389-394
Electron absorption and equilibrium of the Schiffs bases prepared between pyridoxal 5′-phosphate (PLP) and dodecylamine (DODA) or some other shorter chain amines have been studied in nonionic and cationic micellar solutions with various pH of the bulk solution. In the presence of the nonionic (Triton X-100) micelles the Schiffs bases formed between PLP and DODA were embedded into the micelles because the absorption occured at 335 nm, indicative of the nonpolar milieu. This absorption was constant at pH 5–10. At pH 3–5, the tautomeric form absorbing at 415 nm appeared. This resembles the titration of glycogen phosphorylate or that of Schiffs bases in methanol. Short chain amines absorbed at 415 nm, which is typical of Schiffs bases in aqueous solutions. Tryptophan also absorbed first at 415 nm but the absorption changed to 325 nm with a half-time of ~20 min. This was interpreted as being due to formation of the cyclic structure catalysed by micelles. The pH-dependent equilibrium constant of the reaction between PLP and DODA in Triton X-100 solution had a maximum at pH9, the value being 3500 M?1, about ten times greater than the value of ethylamine at the same pH. Spectral properties of PLP-DODA imines in the cationic micelles (cetyltrimethylammonium bromide) resembled those in the nonionic micelles, except that at low pH the absorption peak in the 415 nm region did not appear. The equilibrium constant of PLP-DODA had maximum at pH 9, the value being as high as 118000 M?1. Different properties of nonionic and cationic micelles and the design of micellar model systems of PLP enzymes are discussed. 相似文献
47.
Gray R. Kunkel Margarete Mehrabian Harold G. Martinson 《Molecular and cellular biochemistry》1981,34(1):3-13
Summary Contact-site cross-linking agents comprise a heterogeneous grouping of cross-linkers which share the common property of being
able to cross-link only very closely juxtaposed residues in macromolecular complexes. We have defined contact-site cross-linking
arbitrarily as the covalent joining of residues such that they are constrained to a distance which is equivalent to or less
than their closest possible steric approach prior to becoming linked (1). We recognize two classes of contact-site cross-linkers,
bridge type and zero-length type. The former, such as formaldehyde, become incorporated during cross-linking as one-atom bridges.
The latter, such as the carbodiimides, operate as condensing agents with the result that the cross-linked residues become
interjoined directly.
Contact-site cross-linkers have been used in several ways as specific probes of both the static and dynamic aspects of macromolecular
structure. They can yield precise structural information about macromolecular contacts when actual sites of cross-linking
are determined by peptide or nucleotide mapping techniques. In this way exact contacs between histones in the nucleosome,
between protein and RNA in the ribosome, and between RNA polymerase and DNA have been determined. Contact-site cross-linkers
have also been used to probe the perturbation of contacts following macromolecular conformational changes. Certain histonehistone
‘cross-linkable’ sites are rendered unreactive after induction of chromatin conformational changes thus serving to localize
sites of perturbation. 相似文献
48.
49.
The subcellular distribution of dystrophin in mouse skeletal, cardiac, and smooth muscle 总被引:21,自引:10,他引:11
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We use a highly specific and sensitive antibody to further characterize the distribution of dystrophin in skeletal, cardiac, and smooth muscle. No evidence for localization other than at the cell surface is apparent in skeletal muscle and no 427-kD dystrophin labeling was detected in sciatic nerve. An elevated concentration of dystrophin appears at the myotendinous junction and the neuromuscular junction, labeling in the latter being more intense specifically in the troughs of the synaptic folds. In cardiac muscle the distribution of dystrophin is limited to the surface plasma membrane but is notably absent from the membrane that overlays adherens junctions of the intercalated disks. In smooth muscle, the plasma membrane labeling is considerably less abundant than in cardiac or skeletal muscle and is found in areas of membrane underlain by membranous vesicles. As in cardiac muscle, smooth muscle dystrophin seems to be excluded from membrane above densities that mark adherens junctions. Dystrophin appears as a doublet on Western blots of skeletal and cardiac muscle, and as a single band of lower abundance in smooth muscle that corresponds most closely in molecular weight to the upper band of the striated muscle doublet. The lower band of the doublet in striated muscle appears to lack a portion of the carboxyl terminus and may represent a dystrophin isoform. Isoform differences and the presence of dystrophin on different specialized membrane surfaces imply multiple functional roles for the dystrophin protein. 相似文献
50.
Mechanisms of food selection in Daphnia 总被引:1,自引:0,他引:1
A conceptual behavioural and mechanistic Holling-type model of food selection in Daphnia pulicaria is derived from SEM observations with animals feeding on mixtures of spherical-cylindrical diatoms, oblongate green algae, and filamentous cyanobacteria, as well as ultrafine particles. The algae used were Stephanodiscus hantzschii (<- 6 µm length), Monoraphidium setiforme ( 20 µm), and Oscillatoria aghardii (strands, >- 80 µm). Cell (strand) selection can occur at any or all of three stages: (i) interception from the feeding currents, (ii) collection and channeling to the food groove, and (iii) compaction and transport to the mouth. During each stage, given equal initial cell densities, elongate cells are more likely to escape collection than spherical cells and are more likely to be rejected. In addition, filaments require increased handling time at stages (ii) and (iii) and promote entanglement with limb 5 and the postabdominal claw. Food is collected primarily with the aid of limbs 3 (and 4), but limbs 1 and 2 also intervene. Neither the leaky sieve hypothesis alone nor any other single-process hypothesis explains the observations on examined in corpore positions, morphology, and derived movements of the feeding limbs. Attachment and mucus appear to be important for the ingestion of bacteria and ultrafine particles.The model is consistent with many experimental results of differential feeding by Daphnia pulicaria on mixtures of variously shaped algae and other observations on Daphnia feeding behaviour. The paradigm of invariate, nonselective feeding by Daphnia is rejected. 相似文献