全文获取类型
收费全文 | 3396篇 |
免费 | 198篇 |
专业分类
3594篇 |
出版年
2022年 | 18篇 |
2021年 | 38篇 |
2020年 | 25篇 |
2019年 | 31篇 |
2018年 | 43篇 |
2017年 | 39篇 |
2016年 | 57篇 |
2015年 | 91篇 |
2014年 | 111篇 |
2013年 | 244篇 |
2012年 | 152篇 |
2011年 | 199篇 |
2010年 | 111篇 |
2009年 | 129篇 |
2008年 | 182篇 |
2007年 | 199篇 |
2006年 | 193篇 |
2005年 | 184篇 |
2004年 | 179篇 |
2003年 | 210篇 |
2002年 | 163篇 |
2001年 | 83篇 |
2000年 | 100篇 |
1999年 | 82篇 |
1998年 | 53篇 |
1997年 | 41篇 |
1996年 | 31篇 |
1995年 | 32篇 |
1994年 | 35篇 |
1993年 | 28篇 |
1992年 | 39篇 |
1991年 | 37篇 |
1990年 | 35篇 |
1989年 | 36篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 26篇 |
1985年 | 35篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1978年 | 21篇 |
1977年 | 15篇 |
1975年 | 24篇 |
1974年 | 13篇 |
1973年 | 17篇 |
1972年 | 13篇 |
1966年 | 9篇 |
排序方式: 共有3594条查询结果,搜索用时 0 毫秒
91.
Nei T Urano S Motoi N Takizawa J Kaneko C Kanazawa H Tazawa R Nakagaki K Akagawa KS Akasaka K Ichiwata T Azuma A Nakata K 《American journal of physiology. Lung cellular and molecular physiology》2012,302(9):L959-L964
The granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibody (GMAb) is the causative agent underlying autoimmune pulmonary alveolar proteinosis (aPAP). It consists primarily of the IgG isotype. At present, information on other isotypes of the autoantibody is limited. We detected serum the IgM isotype of GMAb (IgM-GMAb) in more than 80% of patients with aPAP and 22% of healthy subjects, suggesting that a continuous antigen pressure may be present in most patients. Levels of the IgM isotype were weakly correlated with IgG-GMAb levels but not IgA-GMAb, suggesting that its production may be associated with that of IgG-GMAb. The mean binding avidity to GM-CSF of the IgM isotype was 100-fold lower than the IgG-GMAb isotype, whereas the IC(50) value for neutralizing capacity was 20,000-fold higher than that of IgG-GMAb, indicating that IgM-GMAb is only a very weak neutralizer of GM-CSF. In bronchoalveolar lavage fluid from nine patients, IgG-GMAb was consistently detected, but IgM-GMAb was under the detection limit in most patients, confirming that IgM-GMAb is functionally a bystander in the pathogenesis of aPAP. It rather may be involved in the mechanism for development of IgG-GMAb in vivo. 相似文献
92.
Asai Takami Kaneita Yoshitaka Uchiyama Makoto Takemura Shinji Asai Satoshi Yokoyama Eise Miyake Takeo Harano Satoru Suzuki Kenshu Ibuka Eiji Kaneko Akiyo Tsutsui Takako Ohida Takashi 《Sleep and biological rhythms》2006,4(1):55-62
Sleep and Biological Rhythms - There have been only a few studies on the relationship between sleep disturbances and somatic and psychological complaints in Japanese people. In this study, we... 相似文献
93.
Somfai T Ozawa M Noguchi J Kaneko H Karja NW Fahrudin M Nakai M Maedomari N Dinnyés A Nagai T Kikuchi K 《Animal reproduction science》2008,107(1-2):131-147
Embryo development during in vitro culture of polyspermic porcine oocytes was investigated in the present study. After in vitro fertilization (IVF) of in vitro matured oocytes, putative zygotes were centrifuged to visualize pronuclei. Two pronuclear (2PN) and poly-pronuclear (PPN) zygotes were selected and cultured in vitro. Their development to the blastocyst stage and total cell numbers, dead cell rates and ploidy at the blastocyst stage and morphology of resultant embryos after first cleavage were compared. A cleavage rate of PPN embryos was lower than that of 2PN (61.3% and 82.2%, respectively), however, the ability of cleaved embryos to develop to the blastocyst stage did not differ between the PPN and the 2PN groups (22.4% and 32.9%, respectively). Also there was no difference in total cell numbers and rates of dead cells between PPN and 2PN blastocysts. The majority of blastocysts in 2PN group were found to be diploid. In contrast, blastocysts in PPN group showed heterogeneous status in their ploidy including polyploidy and mixoploidy, whereas a remarkable proportion (31.3%) of them was found to be diploid. After the first cleavage (at 36 h after IVF), there was no difference in the number of nuclei/embryo between the two groups, nevertheless embryos in PPN group had significantly higher numbers of blastomeres than that of embryos in 2PN group, mainly due to an increased frequency of anuclear blastomeres. The present results indicate that correction of embryo ploidy in polyspermic embryos can occur during IVC. Nevertheless the frequency of partial fragmentation in polyspermic embryos is increased. 相似文献
94.
A flavone glucoside, luteolin-7-O-glucoside (luteolin-7-G) inhibited the formation of pentyl and 7-carboxyheptyl radicals in the reaction of 13-hydroperoxy-9,11-octadecadienoic (13-HPODE) acid with iron(II) ions. The inhibitory effect of luteolin-7-G was diminished in the presence of EDTA. These results indicated that the inhibitory effects of luteolin-7-G occur partly through the chelation of iron ions. Measurement of visible spectra also showed that luteolin-7-G chelates iron ions. On the other hand, luteolin-7-G did not inhibit the reaction under anaerobic conditions, suggesting that oxygen molecules participate in the inhibition. Oxygen consumption measurements showed that the luteolin-7-G/iron ion complexes react with oxygen molecules in competition with 13-HPODE acid, and free iron ions exclusively react with 13-HPODE acid. The reaction of luteolin-7-G/iron ion complexes with oxygen molecules possibly diminishes the formation of pentyl and 7-carboxyheptyl radicals. 相似文献
95.
Molecular Characterization of a Deep-Sea Methanotrophic Mussel Symbiont that Carries a RuBisCO Gene 总被引:1,自引:0,他引:1
In our previous investigation on the genes of 1,5-ribulose bisphosphate carboxylase/oxygenase (RuBisCO; EC 4.1.1.39) in deep-sea
chemoautotrophic and methanotrophic endosymbioses, the gene encoding the large subunit of RuBisCO form I (cbbL) had been detected in the gill of a mussel belonging to the genus Bathymodiolus from a western Pacific back-arc hydrothermal vent. This study further examined the symbiont source of the RuBisCO cbbL gene along with the genes of 16S ribosomal RNA (16S rDNA) and particulate methane monooxygenase (EC 1.14.13.25; pmoA) and probed for the presence of the ATP sulfurylase gene (EC 2.7.7.4; sopT). The 16S rDNA sequence analysis indicated that the mussel harbors a monospecific methanotrophic Gammaproteobacterium. This
was confirmed by amplification and sequencing of the methanotrophic pmoA, while thiotrophic sopT was not amplified from the same symbiotic genome DNA. Fluorescence in situ hybridization demonstrated simultaneous occurrence of the symbiont-specific 16S rDNA, cbbL and pmoA, but not sopT, in the mussel gill. This is the first molecular and visual evidence for a methanotrophic bacterial endosymbiont that bears
the RuBisCO cbbL gene relevant to autotrophic CO2 fixation. 相似文献
96.
Leuschner F Dutta P Gorbatov R Novobrantseva TI Donahoe JS Courties G Lee KM Kim JI Markmann JF Marinelli B Panizzi P Lee WW Iwamoto Y Milstein S Epstein-Barash H Cantley W Wong J Cortez-Retamozo V Newton A Love K Libby P Pittet MJ Swirski FK Koteliansky V Langer R Weissleder R Anderson DG Nahrendorf M 《Nature biotechnology》2011,29(11):1005-1010
Excessive and prolonged activity of inflammatory monocytes is a hallmark of many diseases with an inflammatory component. In such conditions, precise targeting of these cells could be therapeutically beneficial while sparing many essential functions of the innate immune system, thus limiting unwanted effects. Inflammatory monocytes-but not the noninflammatory subset-depend on the chemokine receptor CCR2 for localization to injured tissue. Here we present an optimized lipid nanoparticle and a CCR2-silencing short interfering RNA that, when administered systemically in mice, show rapid blood clearance, accumulate in spleen and bone marrow, and localize to monocytes. Efficient degradation of CCR2 mRNA in monocytes prevents their accumulation in sites of inflammation. Specifically, the treatment attenuates their number in atherosclerotic plaques, reduces infarct size after coronary artery occlusion, prolongs normoglycemia in diabetic mice after pancreatic islet transplantation, and results in reduced tumor volumes and lower numbers of tumor-associated macrophages. 相似文献
97.
98.
99.
Banno Y Nemoto S Murakami M Kimura M Ueno Y Ohguchi K Hara A Okano Y Kitade Y Onozuka M Murate T Nozawa Y 《Journal of neurochemistry》2008,104(5):1372-1386
The present study examined the role of phospholipase D2 (PLD2) in the regulation of depolarization-induced neurite outgrowth and the expression of growth-associated protein-43 (GAP-43) and synapsin I in rat pheochromocytoma (PC12) cells. Depolarization of PC12 cells with 50 mmol/L KCl increased neurite outgrowth and elevated mRNA and protein expression of GAP-43 and synapsin I. These increases were suppressed by inhibition of Ca2+ -calmodulin-dependent protein kinase II (CaMKII), PLD, or mitogen-activated protein kinase kinase (MEK). Knockdown of PLD2 by small interfering RNA (siRNA) suppressed the depolarization-induced neurite outgrowth, and the increase in GAP-43 and synapsin I expression. Depolarization evoked a Ca2+ rise that activated various signaling enzymes and the cAMP response element-binding protein (CREB). Silencing CaMKIIδ by siRNA blocked KCl-induced phosphorylation of proline-rich protein tyrosine kinase 2 (Pyk2), Src kinase, and extracellular signal-regulated kinase (ERK). Inhibition of Src or MEK abolished phosphorylation of ERK and CREB. Furthermore, phosphorylation of Pyk2, ERK, and CREB was suppressed by the PLD inhibitor, 1-butanol and transfection of PLD2 siRNA, whereas it was enhanced by over-expression of wild-type PLD2. Depolarization-induced PLD2 activation was suppressed by CaMKII and Src inhibitors, but not by MEK or protein kinase A inhibitors. These results suggest that the signaling pathway of depolarization-induced PLD2 activation was downstream of CaMKIIδ and Src, and upstream of Pyk2(Y881) and ERK/CREB, but independent of the protein kinase A. This is the first demonstration that PLD2 activation is involved in GAP-43 and synapsin I expression during depolarization-induced neuronal differentiation in PC12 cells. 相似文献
100.
Simple sequence repeat (SSR) markers were developed in the water lotus (Nelumbo nucifera Gaertn.) from an SSR-enriched genomic library. Of the SSR markers tested, 11 primer pairs produced clearly distinguishable DNA banding patterns. Forty-three alleles were detected with the 11 markers. The allele number per locus ranged from 2 to 5 with an average of 3.9. Polymorphism values ranged from 0.11 to 0.66 with an average of 0.51. These primers were also applicable to another Nelumbo species, Nelumbo lutea (Willd.) Pers. (American lotus) and hybrids between N. nucifera and N. lutea. These results indicate that the SSR markers developed in this study are informative and will be useful for genetic analysis in Nelumbo species. 相似文献