全文获取类型
收费全文 | 1316篇 |
免费 | 143篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 29篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 58篇 |
2014年 | 60篇 |
2013年 | 61篇 |
2012年 | 91篇 |
2011年 | 103篇 |
2010年 | 61篇 |
2009年 | 50篇 |
2008年 | 79篇 |
2007年 | 75篇 |
2006年 | 64篇 |
2005年 | 79篇 |
2004年 | 71篇 |
2003年 | 74篇 |
2002年 | 56篇 |
2001年 | 30篇 |
2000年 | 19篇 |
1999年 | 17篇 |
1998年 | 20篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1967年 | 4篇 |
排序方式: 共有1459条查询结果,搜索用时 15 毫秒
1.
Three Approaches to the Study of Language and Gender 总被引:1,自引:0,他引:1
Bonnie McElhinny 《American anthropologist》2003,105(4):848-852
Gender across Languages: The Linguistic Representation of Women and Men. Vol. 2. Marlis Hellinger and Hadumod Bußmann eds. Amsterdam: John Benjamins, 2002. 348 pp.
Gender Identity and Discourse Analysis. Lia Litosseliti and Jane Sunderland eds. Amsterdam: John Benjamins, 2002. 335 pp.
Talking Gender and Sexuality. Paul McIlvenny. ed. Amsterdam: John Benjamins, 2002. 327 pp. 相似文献
Gender Identity and Discourse Analysis. Lia Litosseliti and Jane Sunderland eds. Amsterdam: John Benjamins, 2002. 335 pp.
Talking Gender and Sexuality. Paul McIlvenny. ed. Amsterdam: John Benjamins, 2002. 327 pp. 相似文献
2.
Melinda Bonnie Fagan 《Biology & philosophy》2012,27(2):179-213
Stem cell biology and systems biology are two prominent new approaches to studying cell development. In stem cell biology,
the predominant method is experimental manipulation of concrete cells and tissues. Systems biology, in contrast, emphasizes
mathematical modeling of cellular systems. For scientists and philosophers interested in development, an important question
arises: how should the two approaches relate? This essay proposes an answer, using the model of Waddington’s landscape to
triangulate between stem cell and systems approaches. This simple abstract model represents development as an undulating surface
of hills and valleys. Originally constructed by C. H. Waddington to visually explicate an integrated theory of genetics, development
and evolution, the landscape model can play an updated unificatory role. I examine this model’s structure, representational
assumptions, and uses in all three contexts, and argue that explanations of cell development require both mathematical models
and concrete experiments. On this view, the two approaches are interdependent, with mathematical models playing a crucial
but circumscribed role in explanations of cell development. 相似文献
3.
4.
Human λ light chain locus: Organization and DNA sequences of three genomicJ regions 总被引:14,自引:0,他引:14
Evidence for the genomic organization of human lambda light chain joining (J) region gene segments is presented. A mouse J probe was used in Southern hybridizations to localize joining region sequences in a cosmid clone containing the genomic cluster of six human lambda constant (C) region gene segments. The results of these hybridizations suggest the presence of at least one J gene segment upstream from each constant region gene segment. The DNA sequences indicate that the human JI, J2, and J3 gene segments have consensus nonamer and heptamer sequences, proposed to be involved in V-J joining, are capable of encoding the known amino acid sequences for the respective J peptides, and have a sequence which could give functional RNA splice site at the end of their coding regions. Our data show that a single functional J is located 1.3 or 1.6 kb upstream of each of the C gene segments known to encode the Mcg, Kern– Oz–, and Kern–Oz+ isotypes. Therefore, the gene organization of this region of the human lambda locus is J1 CI -J2C2-J3C3. The DNA sequences ofJ
1,J
2, andJ
3 presented in this paper establish that a singleJ
gene segment precedes each expressed C gene segment, and support a model for the evolution of the human JC clusters where JICI andJ2C2-J3C3. arose from different ancestral JC units. 相似文献
5.
Raymond R. Wilson Jr Joseph F. Siebenaller Bonnie J. Davis 《Biochemical Systematics and Ecology》1990,18(7-8):565-572
The heart-type lactate dehydrogenase (LDH-B4) homologs of two species of Nezumia and eight species of Coryphaenoides are isomobile on two commonly used electrophoretic buffer systems. To test the hypothesis that the homologs possess the same primary structures, the allozymes from N. bairdii and four species of Coryphaenoides were purified by affinity chromatography on an oxamate aminohexyl Sepharose column and digested with trypsin. The resulting peptide mixtures were then mapped using reversed-phase high-performance liquid chromatography. The peptide maps of the enzyme homologs indicate that the overall similarity of the homologs is high, but unique peptides in each species indicate that the allozymes are not identical in primary structure. 相似文献
6.
The occurrence of polyenoic very long chain fatty acids with greater than 32 carbon atoms in molecular species of phosphatidylcholine in normal and peroxisome-deficient (Zellweger''s syndrome) brain. 总被引:6,自引:1,他引:5
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The n-6 tetra- and pentaenoic fatty acids with carbon chain lengths greater than 32 found in normal brain are located predominantly in a separable species of phosphatidylcholine. A similar phospholipid is found in increased amounts in the brain of peroxisome-deficient (Zellweger's syndrome) patients, but the fatty acid composition differs in that penta- and hexaenoic derivatives predominate. Our data strongly suggest that the polyenoic very long chain fatty acids are confined to the sn-1 position of the glycerol moiety, while the sn-2 position is enriched in saturated, monounsaturated and polyunsaturated fatty acids with less than 24 carbon atoms. It is postulated that these unusual molecular species of phosphatidylcholine may play some, as yet undefined, role in brain physiology. 相似文献
7.
The response of a bumblebee goby,Brachygobius sabanus,to chemical stimuli from injured conspecifics 总被引:1,自引:0,他引:1
Synopsis
Brachygobius sabanus move less often and spend less time swimming when they detect chemicals released from injured conspecifics. This resembles the alarm response found in ostariophysan fishes, darters, and at least one other gobiid. Chemicals from injured Poecilia reticulata do not induce an alarm response in B. sabanus. 相似文献
8.
The crystal structure of Pseudomonas putida cytochrome P-450cam in the substrate-free form has been refined at 2.20-A resolution and compared to the substrate-bound form of the enzyme. In the absence of the substrate camphor, the P-450cam heme iron atom is hexacoordinate with the sulfur atom of Cys-357 providing one axial heme ligand and a water molecule or hydroxide ion providing the other axial ligand. A network of hydrogen-bonded solvent molecules occupies the substrate pocket in addition to the iron-linked aqua ligand. When a camphor molecule binds, the active site waters including the aqua ligand are displaced, resulting in a pentacoordinate high-spin heme iron atom. Analysis of the Fno camphor - F camphor difference Fourier and a quantitative comparison of the two refined structures reveal that no detectable conformational change results from camphor binding other than a small repositioning of a phenylalanine side chain that contacts the camphor molecule. However, large decreases in the mean temperature factors of three separate segments of the protein centered on Tyr-96, Thr-185, and Asp-251 result from camphor binding. This indicates that camphor binding decreases the flexibility in these three regions of the P-450cam molecule without altering the mean position of the atoms involved. 相似文献
9.
Patsy M. Brannon Bonnie M. Orrison Norman Kretchmer 《In vitro cellular & developmental biology. Plant》1985,21(1):6-14
Summary Rat pancreatic acinar cells were isolated and cultured in Ham's F12 medium with 15% bovine calf serum. Caerulein, insulin,
somatostatin, and dexamethasone (DEX) had no effect on intracellular or secreted amylase in these cultured cells. A serum-free
medium, using Waymouth's MB 752/1 supplemented with albumin, epidermal growth factor (EGF), DEX, and HEPES, was then developed
to avoid serum factors that might mask hormonal effects. In this SF medium, pancreatic acinar, cells maintained the morphological
and ultrastructural characteristics of freshly isolated cells and secreted amylase in response to the secretagogue, carbamyl
choline. Insulin, at a concentration of 1 μg/ml, significantly increased intracellular and secreted amylase activity after
3 d. This model cell system can be used to study the regulation of the synthesis of amylase and other pancreatic enzymes in
vitro. 相似文献
10.
Detection of a homologous series of C26-C38 polyenoic fatty acids in the brain of patients without peroxisomes (Zellweger''s syndrome). 总被引:2,自引:1,他引:1
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A Poulos P Sharp H Singh D Johnson A Fellenberg A Pollard 《The Biochemical journal》1986,235(2):607-610
The brains of patients with inherited abnormalities in peroxisomal structure and function contain greatly increased proportions of a homologous series of unique polyenoic fatty acids with carbon chain lengths ranging from 26 to 38. Based on evidence by chemical ionization and electron impact mass spectrometry before and after catalytic hydrogenation, and argentation t.l.c., these lipids have been tentatively identified as 26:5, 28:5, 30:5, 30:6, 30:7, 32:5, 32:6, 32:7, 34:5 and 34:6 fatty acids. A further two fatty acids eluting at very high temperatures from gas chromatography columns have been tentatively identified on the basis of their chemical ionization mass spectra as 36:6 and 38:6 fatty acids. 相似文献