全文获取类型
收费全文 | 2895篇 |
免费 | 150篇 |
出版年
2023年 | 3篇 |
2022年 | 14篇 |
2021年 | 32篇 |
2020年 | 16篇 |
2019年 | 29篇 |
2018年 | 33篇 |
2017年 | 34篇 |
2016年 | 58篇 |
2015年 | 89篇 |
2014年 | 109篇 |
2013年 | 145篇 |
2012年 | 194篇 |
2011年 | 200篇 |
2010年 | 121篇 |
2009年 | 109篇 |
2008年 | 167篇 |
2007年 | 204篇 |
2006年 | 171篇 |
2005年 | 189篇 |
2004年 | 182篇 |
2003年 | 170篇 |
2002年 | 169篇 |
2001年 | 51篇 |
2000年 | 40篇 |
1999年 | 53篇 |
1998年 | 30篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 38篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 38篇 |
1991年 | 37篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 7篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有3045条查询结果,搜索用时 15 毫秒
71.
Release of eicosanoids is an important response of macrophages to inflammation and bacterial infection. At low concentrations, bacterial lipopolysaccharide (1-2 micrograms/ml) fails to stimulate eicosanoid release in resident peritoneal macrophages but primes the macrophages for a greatly enhanced release of eicosanoids on stimulation with the calcium ionophore A23187 (0.1 microM) or with phorbol 12-myristate 13-acetate (50 nM), an activator of protein kinase C. Incubation of macrophages with Bordetella pertussis toxin, prior to priming with lipopolysaccharide, inhibited the release of both cyclooxygenase and lipoxygenase products upon A23187 stimulation. Pertussis toxin treatment of macrophages had no effect on eicosanoid release when the stimulus was phorbol 12-myristate 13-acetate. The presence of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an effective inhibitor of protein kinase C, during lipopolysaccharide priming and subsequent stimulation significantly inhibited eicosanoid release when phorbol 12-myristate 13-acetate was the stimulus, but did not affect eicosanoid release stimulated by A23187. Based on these results, at least two mechanisms, distinguished by apparent differences in sensitivity to pertussis-toxin-sensitive, guanine-nucleotide-binding proteins and protein kinase C, are involved in eicosanoid secretion by lipopolysaccharide-activated macrophages in response to A23187 and phorbol 12-myristate 13-acetate. 相似文献
72.
J S Allen K Matsunaga T Nakamura F Kitamura T Furukawa S S Hacisalihzade V M Sarich L Stark 《Human biology; an international record of research》1990,62(3):337-352
Smooth-pursuit eye-tracking dysfunction is a putative genetic trait marker for schizophrenia. In this study 88 Japanese schizophrenics from Kyushu and Okinawa were examined for the marker using precise high-resolution instrumentation: 76% of the schizophrenics from Kyushu and 89% of those from Okinawa had pursuit dysfunction. The presence of the culture-neutral smooth-pursuit marker for schizophrenia in Japan demonstrates that the etic concept "schizophrenia" is cross-culturally valid. Furthermore, the ubiquity of the marker in biologically and culturally diverse populations may indicate a limit on the extent of meaningful heterogeneity likely to be discovered within the condition. 相似文献
73.
Structure of cloned delta-globin genes from a normal subject and a patient with delta-thalassemia; sequence polymorphisms found in the delta-globin gene region of Japanese individuals. 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A Kimura E Matsunaga Y Ohta T Fujiyoshi T Matsuo T Nakamura T Imamura T Yanase Y Takagi 《Nucleic acids research》1982,10(19):5725-5732
The delta-globin genes of a normal Japanese and a Japanese patient with homozygous delta-thalassemia were cloned, and the nucleotide sequence of a region including the gene was determined. Comparison of the nucleotide sequences of these two individuals with that of pH delta 1, delta-globin clone from the gene library constructed by Maniatis et al., showed differences in the large intervening sequence (IVS 2), at positions 137, 151, 186, 188, 291, 292 and 540 as one base substitutions, at 339 and 823 as one base additions, at 548 as a one base deletion, and a 9 bp duplication between positions 651 and 659, and differences in the 3'-flanking sequence at 51 and 98 nucleotides 3' to the AATAAA sequence. However, in the region studied, no differences was observed in the nucleotide sequences of the normal subject and the patient with delta-thalassemia. Therefore, these differences may represent polymorphisms of the delta-globin gene present in Japanese individuals. These data suggest that IVS 2 is more divergent than other regions, and that a DNA region(s) other than the globin gene may affect expression of the gene. 相似文献
74.
Ei Matsunaga 《Human genetics》1980,54(1):127-128
Summary Centrometric fission of chromosome 10 is reported in a 25-year-old psychiatric patient and his 51/2-year-old normal daughter. The relevant literature on this subject is briefly reviewed. 相似文献
75.
Naoko Kawamura 《Chromosoma》1979,74(2):179-188
Mosaic silkworms were induced when the hybrid eggs of two strains with different egg color and larval markings were exposed to low temperature. Cytological studies were conducted to find out the relation between mosaic larval pattern and ploidy in reproductive cells along with demonstration of chromosomes in the mosaic embryos. — Mosaic eggs eith the characters of both the father and the hybrid were two types, one with large serosa nuclei (LN-mosaic) and the other with small serosa nuclei (SN-mosaic). The cytological studies demonstrated that LN-mosaic individuals were 2n/4n, while SN-mosaic ones were n/2n. In both types of silkworms, cell ploidy level in nuclei of synkaryon origin was two times that of androgenic ones. — From the results obtained in the present studies as well as in the previous studies, a possible mechanism of induction of mosaicism in silkworms by cold shock is contemplated. 相似文献
76.
An endo-(1→6)-β-D-glucanase (EC 3.2.1), isolated from the culture filtrate of Mucor hiemalis, was purified by ammonium sulphate fractionation and gel filtration. The homogeneity of the enzyme was confirmed by disc electrophoresis. The enzyme had a wide range of temperature and pH stability, high substrate specificity, and an action pattern of the endo-type. 相似文献
77.
M Fukushima Y Suzuki Y Toira I Matsunaga K Ochi H Nagano 《Biochemical and biophysical research communications》1975,66(2):632-638
The metabolism of 1α-hydroxyvitamin D3 (1α-OH-D3) was studied in rat liver perfused with [3H]-1α-OH-D3. [3H]-1α-OH-D3 was converted very rapidly to a more polar metabolite, which was identified as 1α,25-dihydroxy-vitamin D3 [1α,25-(OH)2-D3] by co-chromatography with synthetic 1α,25-(OH)2-D3 as well as by gas chromatography-mass spectrometry. [3H]-1α,25-(OH)2-D3 appeared in the perfusate as early as 20 min after addition of [3H]-1α-OH-D3, and its level in the perfusate increased linearly for at least 120 min. These data strongly indicate that 1α-OH-D3 is metabolized to 1α,25-(OH)2-D3, which exerts biological effects on bone and intestine. 相似文献
78.
A molecular species of sialic acid was isolated in a free form from cerumen of the wet type, but not of the dry type, by an ion-exchange column chromatography and preparative high-performance liquid chromatography. Structural analysis of this sialic acid was performed by gas-liquid chromatography/mass spectrometry with chemical ionization (CI) and electron ionization (EI). In the CI mass spectra, the protonated molecular ion of the trimethylsilyl derivative was observed at m/z 580. and that of the methyl ester-trimethylsilyl derivative was at m/z 522. In the EI mass spectrum, the methyl ester-trimethylsilyl derivative gave characteristic ions at m/z 506, 462, 418, 416, 328, 316, 238, 228, 205, 186, and 173. This mass spectrum was identical with that of 2,7-anhydro-N-acetylneuraminic acid, which was reported by Lifely and Cottee (Carbohydr. Res. 107, 187-197, 1982) as the mass spectrum of a by-product prepared from N-acetylneuraminic acid by methanolysis. These results indicate that the compound in the wet cerumen is 2,7-anhydro-N-acetylneuraminic acid. Since this sialic acid species could not be detected in cerumens of the dry type, its formation in the wet type may be controlled by an autosomal dominant gene. 相似文献
79.
80.
Summary Chromosome variants were evaluated on the basis of their DNA-replication pattern (LBA). The size of late-replicating centromeric heterochromatin of chromosomes 2, 5, 6, 7, 8, 10, 11, 12, 17, 18, 19, and 20, i.e., pairs without Q or C (qh) variants, was measured by means of a microdensitometer. The results were expressed in area, related to that of a euchromatic segment of a given chromosome, and were assigned into five classes based on the difference in standard deviation from an average relative size. LBA variants in each of 12 pairs were found in 29%–42% of the chromosomes. 相似文献