全文获取类型
收费全文 | 1356篇 |
免费 | 92篇 |
出版年
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 35篇 |
2014年 | 55篇 |
2013年 | 97篇 |
2012年 | 78篇 |
2011年 | 92篇 |
2010年 | 53篇 |
2009年 | 52篇 |
2008年 | 86篇 |
2007年 | 103篇 |
2006年 | 82篇 |
2005年 | 78篇 |
2004年 | 88篇 |
2003年 | 83篇 |
2002年 | 97篇 |
2001年 | 8篇 |
2000年 | 24篇 |
1999年 | 19篇 |
1998年 | 26篇 |
1997年 | 20篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1962年 | 2篇 |
1961年 | 3篇 |
排序方式: 共有1448条查询结果,搜索用时 15 毫秒
71.
Concerted changes in the YB2/RYB-a protein and protamine 2 messenger RNA in the mouse testis under heat stress 总被引:2,自引:0,他引:2
Translation of a number of mRNAs is under strict regulation via RNA-binding proteins in the spermatogenic cells of testes. A family of Y-box binding proteins represents promising candidates for these presently uncharacterized RNA-binding proteins. The effects of heat stress on the expression of a Y-box binding protein, YB2/RYB-a, and mouse protamine 2 (mP2) were investigated in cultured spermatogenic cells and mouse testes by immunoblot and Northern blot analyses. Localization and alterations in the expression of the YB2/RYB-a protein and the mP2 mRNA in heat-stressed testes were examined by immunohistochemistry and in situ hybridization, respectively. Levels of the YB2/RYB-a protein in spermatogenic cells decreased rapidly as the result of exposure to higher temperature, 37 degrees C or 43 degrees C, compared with the scrotal temperature, 32.5 degrees C, under the culture conditions used. In experimental cryptorchidism, levels of the YB2/RYB-a protein were decreased after Day 10, while the mRNA levels were affected only slightly. The levels of the mP2 mRNA were also decreased and about comparable with those of the YB2/RYB-a protein. Exposure of the lower abdomen to a high temperature, 43 degrees C for 15 min, also damaged the testis and led to a decrease in YB2/RYB-a protein and the mP2 mRNA levels in a coordinated manner. Because YB2/RYB-a is proposed to function as a stabilizer of mP2 mRNA, the perturbation of YB2/RYB-a by heat stress could account for the decline of the mP2 mRNA in elongated spermatids. 相似文献
72.
Strictly polyphosphate-dependent glucokinase in a polyphosphate-accumulating bacterium,Microlunatus phosphovorus
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tanaka S Lee SO Hamaoka K Kato J Takiguchi N Nakamura K Ohtake H Kuroda A 《Journal of bacteriology》2003,185(18):5654-5656
ATP-dependent glucokinase is suggested to have evolved from a hypothetical polyphosphate (polyP)-dependent glucokinase (polyP-GK) via a bifunctional polyP/ATP glucokinase (polyP/ATP-GK). Here we showed that polyP-GK is present in a polyP-accumulating bacterium, Microlunatus phosphovorus. The polyP-GK produced glucose-6-P(i) from glucose and polyP, but it could not phosphorylate glucose with ATP. The polyP-GK was most closely related to the polyP/ATP-GK of Mycobacterium tuberculosis. 相似文献
73.
Weiming Zheng Junichi Izaki Shuichi Furusawa Yukinori Yoshimura 《Biological procedures online》2001,3(1):1-7
We established a sensitive non-radioactive in situ hybridization (ISH) method for the detection of chicken IgG γ-chain mRNA in paraffin sections. RNA probes were transcribed
in vitro fromcloned chicken IgG CH1 nucleotide sequences with SP6/T7 RNA polymerases in the presence of DIG-UTP. These probes
were used for hybridization and were immunodetected using anti-DIG antibodies conjugated to horseradish peroxidase. The immunoreactive
products were visualized with DAB-H2O2. IgG γ-chain mRNA-expressing cells were localized in both the spleen and oviductal tissues. This method demonstrated an excellent
sensitivity since the ISH signal was clear and the background was negligible. We found that in the spleen IgG γ-chain mRNA-expressing
cells were present mainly in the red pulp, whereas in the oviduct they appeared mainly in the mucosal stroma and not in the
mucosal epithelium.
Published: May 14, 2001. 相似文献
74.
With recent advances in genetic engineering, tumor biology, and immunology, gene therapy has been recognized as a promising new treatment option for various cancers, including prostate cancer. Several clinical trials of prostate cancer gene therapy, using therapeutic genes which include suicide genes, immunomodulatory genes, tumor suppressor genes, and anti-oncogenes, are under way and preliminary reports have emerged. Although gene therapy for prostate cancer is still at an early stage and requires additional technological breakthroughs, new insights obtained from recent clinical trials indicate a promising potential for prostate cancer gene therapy. In this report, general concepts, current progress, and future prospects in prostate cancer gene therapy are summarized. 相似文献
75.
Watanabe K Murakami K Maeda K Fujioka T Nasu M Nishizono A 《Microbiology and immunology》2002,46(7):441-447
During Helicobacter pylori infection, T cell response is critical in the development of active gastritis and in protective immunity against infection. We studied gastric inflammation and T cell response in H. pylori-challenged mice following an intraperitoneal immunization, using whole H. pylori lysate (HpAg) in the absence of adjuvants. H. pylori-challenged mice without immunization developed moderate to severe gastric inflammation, and splenocytes from these mice produced Th1 polarizing cytokines in response to HpAg and Con A during the acute infection. On the other hand, immunized-challenged mice (those inoculated with H. pylori following immunization) had little or no gastric inflammation despite persistent H. pylori colonization. Our immunization primed splenocytes to produce IL-2, IFN-gamma, and IL-4 in response to HpAg and Con A before infection. However, these cells became hyporesponsive to both stimulants immediately after live bacterial challenge in terms of the production of these cytokines, especially IL-2 and IFN-gamma. CTLA-4 has been documented to be a negative regulator of IL-2 production and lymphoproliferation that induces peripheral tolerance and functions 24-72 hr after the initiation of T cell activation. Compared with challenged mice, T cells from immunized-challenged mice showed higher levels of CTLA-4 expression at 72 hr after oral challenge. These data suggested that our immunization inhibited the development of H. pylori-associated gastritis and induced T cell hyporesponsiveness to H. pylori infection, which might be mediated by the early induction of CTLA-4 following challenge. 相似文献
76.
Morohoshi T Maruo T Shirai Y Kato J Ikeda T Takiguchi N Ohtake H Kuroda A 《Applied and environmental microbiology》2002,68(8):4107-4110
The biological process for phosphate (P(i)) removal is based on the use of bacteria capable of accumulating inorganic polyphosphate (polyP). We obtained Escherichia coli mutants which accumulate a large amount of polyP. The polyP accumulation in these mutants was ascribed to a mutation of the phoU gene that encodes a negative regulator of the P(i) regulon. Insertional inactivation of the phoU gene also elevated the intracellular level of polyP in Synechocystis sp. strain PCC6803. The mutant could remove fourfold more P(i) from the medium than the wild-type strain removed. 相似文献
77.
Essential role of the adhesion receptor LFA-1 for T cell-dependent fulminant hepatitis 总被引:6,自引:0,他引:6
Matsumoto G Tsunematsu S Tsukinoki K Ohmi Y Iwamiya M Oliveira-dos-Santos A Tone D Shindo J Penninger JM 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(12):7087-7096
Viral hepatitis affects more than 2 billion people worldwide. In particular, no effective treatment exists to abrogate death and liver damage in fulminant hepatitis. Activation of T cells is an initial and critical event in the pathogenesis of liver damage in autoimmune and viral hepatitis. The precise molecular mechanisms that induce T cell-mediated hepatocyte injury remain largely unclear. In mice, T cell-dependent hepatitis and acute liver damage can be modeled using ConA. In this study, we examined the role of the adhesion receptor LFA-1 in ConA-induced acute hepatic damage using LFA-1(-/-) (CD11a) mice. Massive liver cell apoptosis and metabolic liver damage were observed in LFA-1(+/+) mice following ConA injection. By contrast, LFA-1(-/-) mice were completely resistant to ConA-induced hepatitis and none of the LFA-1(-/-) mice showed any hepatic damage. Whereas activated hepatic T cells remained in the liver in LFA-1(+/+) mice, activated T cells were rapidly cleared from the livers of LFA-1(-/-) mice. Mechanistically, T cells from LFA-1(-/-) mice showed markedly reduced cytotoxicity toward liver cells as a result of impaired, activation-dependent adhesion. Importantly, adoptive transfer of hepatic T cells from LFA-1(+/+) mice, but not from LFA-1(-/-) mice, sensitized LFA-1(-/-) mice to ConA-induced hepatitis. Thus, LFA-1 expression on T cells is necessary and sufficient for T cell-mediated liver damage in vivo. These results provide the first genetic evidence on an adhesion receptor, LFA-1, that has a crucial role in fulminant hepatitis. These genetic data identify LFA-1 as a potential key target for the treatment of T cell-mediated hepatitis and the prevention of liver damage. 相似文献
78.
We conducted a chromosome walk to obtain a DNA fragment downstream of lysJ and found an argE homolog in a putative operon composed of lysJ-orfC-orfD-argE homologs. A knockout mutant of the argE homolog showed significantly slow growth on a minimal medium, and the growth was markedly improved by addition of lysine. We therefore termed this gene lysK. Purified LysK protein has deacetylating activities for both N(2)-acetyllysine and N(2)-acetylornithine at almost equal efficiency. These results suggest that lysK which may share an ancestor with argE functions not only for the lysine biosynthesis, but also for arginine biosynthesis in Thermus thermophilus. 相似文献
79.
Molecular characterization of mammalian dicarbonyl/L-xylulose reductase and its localization in kidney 总被引:6,自引:0,他引:6
Nakagawa J Ishikura S Asami J Isaji T Usami N Hara A Sakurai T Tsuritani K Oda K Takahashi M Yoshimoto M Otsuka N Kitamura K 《The Journal of biological chemistry》2002,277(20):17883-17891
In this report, we first cloned a cDNA for a protein that is highly expressed in mouse kidney and then isolated its counterparts in human, rat hamster, and guinea pig by polymerase chain reaction-based cloning. The cDNAs of the five species encoded polypeptides of 244 amino acids, which shared more than 85% identity with each other and showed high identity with a human sperm 34-kDa protein, P34H, as well as a murine lung-specific carbonyl reductase of the short-chain dehydrogenase/reductase superfamily. In particular, the human protein is identical to P34H, except for one amino acid substitution. The purified recombinant proteins of the five species were about 100-kDa homotetramers with NADPH-linked reductase activity for alpha-dicarbonyl compounds, catalyzed the oxidoreduction between xylitol and l-xylulose, and were inhibited competitively by n-butyric acid. Therefore, the proteins are designated as dicarbonyl/l-xylulose reductases (DCXRs). The substrate specificity and kinetic constants of DCXRs for dicarbonyl compounds and sugars are similar to those of mammalian diacetyl reductase and l-xylulose reductase, respectively, and the identity of the DCXRs with these two enzymes was demonstrated by their co-purification from hamster and guinea pig livers and by protein sequencing of the hepatic enzymes. Both DCXR and its mRNA are highly expressed in kidney and liver of human and rodent tissues, and the protein was localized primarily to the inner membranes of the proximal renal tubules in murine kidneys. The results imply that P34H and diacetyl reductase (EC ) are identical to l-xylulose reductase (EC ), which is involved in the uronate cycle of glucose metabolism, and the unique localization of the enzyme in kidney suggests that it has a role other than in general carbohydrate metabolism. 相似文献
80.
Filamentous bacteriophages of vibrios are integrated into the dif-like site of the host chromosome 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Iida T Makino K Nasu H Yokoyama K Tagomori K Hattori A Okuno T Shinagawa H Honda T 《Journal of bacteriology》2002,184(17):4933-4935
The dif site is located in the replication terminus region of bacterial chromosomes, having a function of resolving dimeric chromosomes formed during replication. We demonstrate that filamentous bacteriophages of vibrios, such as f237 (Vibrio parahaemolyticus) and CTXphi (V. cholerae), are integrated into the dif-like site of host chromosome. 相似文献