全文获取类型
收费全文 | 3267篇 |
免费 | 193篇 |
国内免费 | 11篇 |
专业分类
3471篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 51篇 |
2020年 | 21篇 |
2019年 | 24篇 |
2018年 | 40篇 |
2017年 | 23篇 |
2016年 | 55篇 |
2015年 | 103篇 |
2014年 | 130篇 |
2013年 | 189篇 |
2012年 | 224篇 |
2011年 | 222篇 |
2010年 | 133篇 |
2009年 | 145篇 |
2008年 | 228篇 |
2007年 | 226篇 |
2006年 | 239篇 |
2005年 | 236篇 |
2004年 | 290篇 |
2003年 | 230篇 |
2002年 | 211篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 31篇 |
1998年 | 50篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 28篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1969年 | 2篇 |
排序方式: 共有3471条查询结果,搜索用时 17 毫秒
991.
Thota A Karajgikar M Duan W Gabril MY Chan FL Wong YC Sakai H Chin JL Moussa M Xuan JW 《Journal of cellular biochemistry》2003,88(5):999-1011
Prostate tissue-specific gene expression is crucial for driving potentially therapeutic genes to target specifically to the prostate. Prostate secretory protein of 94 amino acids (PSP94), also known as beta-MSP (microseminoprotein), is one of the three most abundant secretory proteins of the prostate gland, and is generally considered to be prostate tissue-specific. We have previously demonstrated that the expression of the rat PSP94 gene is strictly prostate tissue-specific by an antibody against a recombinant rat PSP94. In order to study prostate targeting utilizing the PSP94 gene in a mouse pre-clinical experimental model, we need to establish antibodies against mouse PSP94 to confirm if it is prostate tissue-specific as well. In this study, firstly we raised a polyclonal antibody against a recombinant glutathione-S-transferase- (GST-) mouse mature form of PSP94. However, it showed very poor immunoreactivity against prostate tissue PSP94 as tested in Western blotting experiments. Neither antibodies against rat PSP94 nor mouse PSP94 showed significant cross-reactivity. Thus a second antibody was established against a recombinant mouse mature PSP94 containing N-terminal polyhistidines, and stronger immunoreactivity against mouse prostate tissue PSP94 was identified in Western blotting experiments. Both of these antibodies showed immunohistochemical reactivity, while the latter showed stronger reactivity in IHC when tested with different fixatives. By studying tissue distribution, we demonstrated that, as with rat PSP94, mouse PSP94 is strictly prostate tissue-specific in experiments of both Western blotting and immunohistochemistry (IHC). This conclusion was also derived from a comparison among antibodies against human, rat, and mouse PSP94, showing very different immunoreactivities in Western blotting and IHC. Finally, a competitive assay between different species was performed. We demonstrated that antibodies against PSP94 from different species (human, primate, rodents) have poor cross-reactivities. These observations also indicate that the PSP94 gene is a rapidly evolving gene in all species. Results from this study have led to the possibility of utilizing PSP94 as a targeting agent specifically to the prostate in a mouse experimental model. 相似文献
992.
A single nucleotide polymorphism (SNP) within the transforming growth factor-beta1 (TGF-beta1) gene was detected by hybridization-based method using bacterial magnetic particles (BMPs). TGF-beta1 is commonly associated with a single base change resulting in a Leu(10)-->Pro (T(869)-->C) polymorphism and is a genetic marker for susceptibility to osteoporosis. Short (9 bases) and specific probes were designed to detect SNP in TGF-beta1. Detection probes were immobilized on BMPs using cross-linking reagents. TGF-beta1 PCR products (139 bp) were labeled with the fluorescent dye coumarin and hybridized with detection probes on BMPs. Complementary hybridized targets gave over four times higher fluorescent intensities, compared with one base mismatched hybridizations. The SNP genotype was successfully discriminated using this technique. 相似文献
993.
Kubota H Kakefuda A Watanabe T Taguchi Y Ishii N Masuda N Sakamoto S Tsukamoto Si 《Bioorganic & medicinal chemistry letters》2003,13(13):2155-2158
A series of (+/-)-2-(3-piperidyl)-1,2,3,4-tetrahydroisoquinolines were prepared and their bradycardic activities were examined in isolated guinea-pigs' right atria and in anesthetized rats. Modifications on the benzyl moiety of the parent compound, 1, led to the identification of compound 11e as a potent and specific bradycardic agent. 相似文献
994.
Urbahns K Härter M Vaupel A Albers M Schmidt D Brüggemeier U Stelte-Ludwig B Gerdes C Tsujishita H 《Bioorganic & medicinal chemistry letters》2003,13(6):1071-1074
Vitronectin receptor (alpha(V)beta(3)) antagonism has been implicated in a variety of disease states, like restenosis, osteoporosis and cancer. In this work, we present the development of a novel class of biphenyl vitronectin receptor antagonists. Identified from a focused combinatorial library based on para-bromo phenylalanine, these compounds show nanomolar affinity to the vitronectin receptor and display unprecedented SAR. Their binding mode can be rationalized by computational docking studies using the X-ray structure of alpha(V)beta(3). 相似文献
995.
Yaoya S Kanho H Mikami Y Itani T Umehara K Kuroyanagi M 《Bioscience, biotechnology, and biochemistry》2004,68(9):1837-1841
Hairy root cultures of Pharbitis nil treated with CuSO4 and methyl jasmonate (MeJA) produced umbelliferone (1) and scopoletin (2) in the culture medium, and skimmin (3), a beta-D-glucopyranoside of 1, was isolated from the hairy roots. While 1 in the medium increased and reached a maximal level 16 h after the treatment with CuSO4, the amount of 3 in the hairy roots decreased, reaching a minimal level after 8 h, before recovering to a level higher than the basal level after 24 h and then continuously increasing. These observations suggest that 1 was released by the hydrolysis of 3. Umbelliferone (1) inhibited hairy root growth, while skimmin (3) did not. This result suggests that, after the release of 1 as a phytoalexin, the hairy roots glycosylated 1 for the detoxification and re-use of 3 as a source of phytoalexin. 相似文献
996.
Itoh M Oh-Ishi S Hatao H Leeuwenburgh C Selman C Ohno H Kizaki T Nakamura H Matsuoka T 《American journal of physiology. Regulatory, integrative and comparative physiology》2004,287(1):R33-R38
Calcium deficiency is considered to increase intracellular calcium level; thus the aim of the current study was to elucidate whether dietary calcium restriction enhanced exercise-induced oxidative stress in rat diaphragm. Twenty male Wistar rats were randomly assigned to either a control group or a group subjected to 1 mo of calcium restriction. In addition, each group was subsequently subdivided into rested or acutely exercised group. Dietary calcium restriction significantly (P < 0.05) upregulated the activities of manganese-superoxide dismutase (Mn-SOD), copper-zinc-superoxide dismutase (Cu-Zn-SOD), and glutathione peroxidase (Gpx) but not catalase. Acute exercise, in addition to calcium restriction, decreased both SOD isoenzymes in the diaphragm of calcium-restricted rats (P < 0.05). On the other hand, calcium restriction resulted in increased Gpx mRNA expression (P < 0.05). In control rats, acute exercise significantly (P < 0.05) increased the expressions of both SOD mRNAs, whereas in the calcium-restricted rats, it increased that of Mn-SOD mRNA (P < 0.05) but decreased that of Gpx mRNA (P < 0.05). Furthermore, reactive carbonyl derivative, a marker of protein oxidation, was significantly greater in the calcium-restricted rats than in the control rats after acute exercise (P < 0.05). The results suggest that antioxidant enzymes in rat diaphragm were upregulated in response to an increased oxidative stress by dietary calcium restriction but that upregulation is not enough to cope with exercise-induced further increase of oxidative stress. 相似文献
997.
998.
Ueno T Tokunaga K Sawa H Maeda M Chiba J Kojima A Hasegawa H Shoya Y Sata T Kurata T Takahashi H 《Microbiology and immunology》2004,48(2):111-118
Gag proteins of human immunodeficiency virus type 1 (HIV-1) play a pivotal role in the budding of the virion, in which the zinc finger motifs of the gag proteins recognize the packaging signal of genomic RNA. Nucleolin, an RNA-binding protein, is identified as a cellular protein that binds to murine leukemia virus (MuLV) gag proteins and regulates the viral budding, suggesting that HIV-1 gag proteins, the packaging signal, psi and nucleolin affect the budding of HIV-1. Here we report that nucleolin enhances the release of HIV-1 virions which contain psi. Furthermore, nucleolin and gag proteins form a complex incorporated into virions, and nucleolin promotes the infectivity of HIV-1. Our results suggest that an empty particle which contains neither nucleolin nor the genomic RNA is eliminated during the budding process, and this mechanism is beneficial for escape from the host immune response against HIV-1. 相似文献
999.
Acute administration of typical and atypical antipsychotics has been reported to induce regionally distinct patterns of c-Fos expression in the rat forebrain. Furthermore, atypical index, the difference in the extent of increased Fos-like immunoreactivity (Fos-LI) in the nucleus accumbens (NAc) shell versus the dorsolateral striatum (DLSt), has been proposed to classify antipsychotics into typical or atypical antipsychotics. The present study was conducted to investigate the atypical properties of 24 antipsychotics that are used in Japan and blonanserin, a novel 5-HT2A and D2 receptor antagonist. We systematically examined the effects of the drugs on Fos-LI in the NAc and DLSt in the rat brain using immunohistochemistry and calculated the atypical index, comparing with those of haloperidol and clozapine. Floropipamide, oxypertine, nemonapride, pimozide and mosapramine, as well as clozapine, olanzapine, quetiapine and risperidone, showed high positive atypical index. Zotepine, perospirone, sulpiride, moperone, sultopride, thioridazine, carpipramine, clocapramine and blonanserin showed moderate ones. In contrast, fluphenazine, bromperidol, timiperone, spiperone, propericiazine, perphenazine, chlorpromazine and levomepromazine had negative atypical index like haloperidol. These results suggest that not only so-called atypical antipsychotics, but also several conventional drugs, possess atypical properties. 相似文献
1000.
Preneoplastic or precancerous lesions in the large bowel have been characterized in terms of morphology and histochemical phenotype. However, the detailed histogenesis and relation of particular lesions to malignancies has not yet to be unequivocally clarified. Aberrant crypt foci (ACF), identified in whole-mount preparations of colonic mucosa in rodents and also recognized in human colon, are now frequently used as effective surrogate biomarkers for experimentally detection of chemopreventive agents against colorectal cancers, but the preneoplastic or precancerous nature of ACF in rodents and humans still remains inconclusive. Relatively recently, early appearing beta-catenin accumulated crypts (BCAC) have been described in en face preparations of colonic mucosa in rodents which differ from ACF in many features. BCAC are suggested to be premalignant rather than preneoplastic. The pathological significance of both lesions, including their advantages and disadvantages as surrogate end points for large bowel neoplasms, and roles in colorectal carcinogenesis are discussed here. 相似文献