全文获取类型
收费全文 | 2148篇 |
免费 | 161篇 |
国内免费 | 1篇 |
出版年
2022年 | 11篇 |
2021年 | 34篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 40篇 |
2015年 | 59篇 |
2014年 | 94篇 |
2013年 | 110篇 |
2012年 | 123篇 |
2011年 | 120篇 |
2010年 | 83篇 |
2009年 | 70篇 |
2008年 | 121篇 |
2007年 | 109篇 |
2006年 | 98篇 |
2005年 | 107篇 |
2004年 | 78篇 |
2003年 | 125篇 |
2002年 | 90篇 |
2001年 | 29篇 |
2000年 | 27篇 |
1999年 | 36篇 |
1998年 | 46篇 |
1997年 | 27篇 |
1996年 | 35篇 |
1995年 | 32篇 |
1994年 | 24篇 |
1993年 | 37篇 |
1992年 | 38篇 |
1991年 | 30篇 |
1990年 | 33篇 |
1989年 | 27篇 |
1988年 | 19篇 |
1987年 | 25篇 |
1986年 | 14篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 25篇 |
1981年 | 18篇 |
1980年 | 23篇 |
1979年 | 25篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1973年 | 11篇 |
排序方式: 共有2310条查询结果,搜索用时 15 毫秒
141.
Seddiki T Delpal S Aubourg A Durand G Ollivier-Bousquet M 《Biology of the cell / under the auspices of the European Cell Biology Organization》2002,94(3):173-185
Plasma-borne prolactin is carried from blood to milk by transcytosis across the mammary epithelial cell through the endocytic and secretory pathways. To determine the precise route of prolactin endocytosis, intracellular transport of biotinylated prolactin was monitored, in parallel with endocytosis of fluorescein isothiocyanate-conjugated dextran and IgG, by using pulse-chase experiments in lactating mammary fragments and in enzymatically dissociated acini. Biotinylated prolactin was sorted to vesiculo-tubular organelles whereas dextran was very rapidly carried to the lumen and IgG remained accumulated in the basal region of cells. To determine whether prolactin uses routes into and across the Golgi and trans-Golgi network, localisation of biotinylated prolactin was combined with the immunofluorescence detection of caseins and, respectively, p58 and TGN38. Biotinylated prolactin strongly colocalised with caseins during a chase but not all or only very little with p58 and TGN38. To characterise the organelles involved in transcytosis, gold-labelled prolactin, experimentally accumulated in late endosomes and which recovered a normal transport, was localised by electron microscopy. In mammary fragments incubated at low temperature, and in mammary fragments from rats fed with a lipid-deprived diet, transport of gold-labelled prolactin was restored by increasing the temperature and by adding arachidonic acid, respectively. These data demonstrate that a sorting occurs very rapidly between prolactin, dextran and IgG. They suggest that prolactin may reach the biosynthetic pathway after direct fusion between multivesicular bodies and secretory vesicles. 相似文献
142.
Secretion of alpha-amylase from Pseudoalteromonas haloplanktis TAB23: two different pathways in different hosts 下载免费PDF全文
Tutino ML Parrilli E Giaquinto L Duilio A Sannia G Feller G Marino G 《Journal of bacteriology》2002,184(20):5814-5817
Secretion of cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis TAB23 was studied in three Antarctic bacteria. We demonstrated that the enzyme is specifically secreted in the psychrophilic hosts even in the absence of a protein domain that has been previously reported to be necessary for alpha-amylase secretion in Escherichia coli. The occurrence of two different secretion pathways in different hosts is proposed. 相似文献
143.
Active form of Notch imposes T cell fate in human progenitor cells 总被引:14,自引:0,他引:14
De Smedt M Reynvoet K Kerre T Taghon T Verhasselt B Vandekerckhove B Leclercq G Plum J 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(6):3021-3029
The crucial role of Notch signaling in cell fate decisions in hematopoietic lineage and T lymphocyte development has been well established in mice. Overexpression of the intracellular domain of Notch mediates signal transduction of the protein. By retroviral transduction of this constitutively active truncated intracellular domain in human CD34+ umbilical cord blood progenitor cells, we were able to show that, in coculture with the stromal MS-5 cell line, depending on the cytokines added, the differentiation toward CD19+ B lymphocytes was blocked, the differentiation toward CD14+ monocytes was inhibited, and the differentiation toward CD56+ NK cells was favored. The number of CD7+cyCD3+ cells, a phenotype similar to T/NK progenitor cells, was also markedly increased. In fetal thymus organ culture, transduced CD34+ progenitor cells from umbilical cord blood cells or from thymus consistently generated more TCR-gammadelta T cells, whereas the other T cell subpopulations were largely unaffected. Interestingly, when injected in vivo in SCID-nonobese diabetic mice, the transduced cells generated ectopically human CD4+CD8+ TCR-alphabeta cells in the bone marrow, cells that are normally only present in the thymus, and lacked B cell differentiation potential. Our results show unequivocally that, in human, Notch signaling inhibits the monocyte and B cell fate, promotes the T cell fate, and alters the normal T cell differentiation pathway compatible with a pretumoral state. 相似文献
144.
145.
146.
147.
Ortega D Raynal M Laudié M Llauro C Cooke R Devic M Genestier S Picard G Abad P Contard P Sarrobert C Nussaume L Bechtold N Horlow C Pelletier G Delseny M 《Comptes rendus biologies》2002,325(7):773-780
Eight hundred and fifty Arabidopsis thaliana T-DNA insertion lines have been selected on a phenotypic basis. The T-DNA flanking sequences (FST) have been isolated using a PCR amplification procedure and sequenced. Seven hundred plant DNA sequences have been obtained revealing a T-DNA insertion in, or in the immediate vicinity of 482 annotated genes. Limited deletions of plant DNA have been observed at the site of insertion of T-DNA as well as in its left (LB) and right (RB) T-DNA signal sequences. The distribution of the T-DNA insertions along the chromosomes shows that they are essentially absent from the centrometric and pericentrometric regions. 相似文献
148.
Global Positioning System (GPS) is an important new technology for spatio-temporal behaviour studies of animals. Differential correction improves location accuracy. Previously, it mostly removed partially the influence of Selective Availability (SA). SA was deactivated in May 2000. The aim of this study was to quantify the influence of SA cancellation on location accuracy of various GPS receivers. We tested the accuracy of locations obtained from non-differential and differential GPS animal collars before and after SA removal. We found a significant improvement in accuracy for both types of GPS collars. However, differential GPS still provides more accurate locations. 相似文献
149.
Genetic diversity and molecular detection of three toxic dinoflagellate genera (Alexandrium,Dinophysis, and Karenia) from French coasts 总被引:6,自引:0,他引:6
Guillou L Nézan E Cueff V Erard-Le Denn E Cambon-Bonavita MA Gentien P Barbier G 《Protist》2002,153(3):223-238
The objectives of this study were 1) to study the genetic diversity of the Alexandrium, Dinophysis and Karenia genera along the French coasts in order to design probes targeting specific DNA regions, and 2) to apply PCR-based detection to detect these three toxic dinoflagellate genera in natural samples. Genetic diversity of these toxic taxa was first studied from either cultures or cells isolated from Lugol-fixed field samples. By this way, partial sequences of the large ribosomal subunit (LSU rDNA) including the variable domains D1 and D2 of A. minutum, Alexandrium species inside the tamarensis complex, the D. acuminata complex and K. mikimotoi were obtained. Next, specific primers were designed for a selection of toxic algae and used during semi-nested PCR detection. This method was tested over a 3-month period on water samples from the Bay of Concarneau (Brittany, France) and on sediment from the Antifer harbor (The English Channel, France). Specificity and sensitivity of this molecular detection were evaluated using the occurrence of target taxa reported by the IFREMER (Institut Fran?ais de Recherche pour l'Exploitation de la Mer) monitoring network based on conventional microscopic examination. This work presents the first results obtained on the biogeographical distribution of genotypes of these three toxic genera along the French coasts. 相似文献
150.
Caufriez A Moreno-Reyes R Leproult R Vertongen F Van Cauter E Copinschi G 《American journal of physiology. Endocrinology and metabolism》2002,282(5):E1147-E1153
To investigate the adaptation of plasma cortisol profiles to an abrupt phase advance of the rest-activity cycle, eight normal young subjects were submitted in a sleep laboratory to an 8-h advance shift of their sleep-wake and dark-light cycles. The shift was achieved by advancing bedtimes from 2300-0700 to 1500-2300. Blood samples were obtained at 20-min intervals for 68 consecutive hours. The shift resulted within 6-9 h in a 3- to 4-h advance of timings of the nadir of the cortisol profile and of the end of the quiescent period but had no immediate effect on the timing of cortisol acrophase. The quiescent period of cortisol secretion was shortened and fragmented. Thus a major advance shift achieved without enforcing sleep deprivation results in a rapid partial adaptation of the temporal profiles of cortisol but also in a marked disruption of the cortisol quiescent period. Sleep onset was consistently followed by a decrease in cortisol concentrations. Conversely, both sleep-wake and dark-light transitions were consistently associated with cortisol secretory pulses. 相似文献