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111.
Wilkes H Rabus R Fischer T Armstroff A Behrends A Widdel F 《Archives of microbiology》2002,177(3):235-243
The anaerobic degradation pathway of the saturated hydrocarbon n-hexane in a denitrifying strain (HxN1) was examined by gas chromatography-mass spectrometry of derivatized extracts from cultures grown with unlabeled and deuterated substrate; several authentic standard compounds were included for comparison. The study was focused on possible reaction steps that follow the initial formation of (1-methylpentyl)succinate from n-hexane and fumarate. 4-Methyloctanoic, 4-methyloct-2-enoic, 2-methylhexanoic, 2-methylhex-2-enoic and 3-hydroxy-2-methylhexanoic acids (in addition to a few other methyl-branched acids) were detected in n-hexane-grown but not in n-hexanoate-grown cultures. Labeling indicated preservation of the original carbon chain of n-hexane in these acids. Tracing of the deuterium label of 3- d1-(1-methylpentyl)succinate in tentative subsequent products indicated a deuterium/carboxyl carbon exchange in the succinate moiety. This suggests that the metabolism of (1-methylpentyl)succinate employs reactions analogous to those in the established conversion of succinyl-CoA via methylmalonyl-CoA to propionyl-CoA. Accordingly, a pathway is proposed in which (1-methylpentyl)succinate is converted to the CoA-thioester, rearranged to (2-methylhexyl)malonyl-CoA and decarboxylated (perhaps by a transcarboxylase) to 4-methyloctanoyl-CoA. The other identified fatty acids match with a further degradation of 4-methyloctanoyl-CoA via rounds of conventional beta-oxidation. Such a pathway would also allow regeneration of fumarate (for n-hexane activation) from propionyl-CoA formed as intermediate and hence present a cyclic process. 相似文献
112.
113.
Buton X Hervé P Kubelt J Tannert A Burger KN Fellmann P Müller P Herrmann A Seigneuret M Devaux PF 《Biochemistry》2002,41(43):13106-13115
The transbilayer movement of glycosphingolipids has been characterized in Golgi, ER, plasma, and model membranes using spin-labeled and fluorescent analogues of the monohexosylsphingolipids glucosylceramide and galactosylceramide and of the dihexosylsphingolipid lactosylceramide. In large unilamellar lipid vesicles, monohexosylsphingolipids underwent a slow transbilayer diffusion (half-time between 2 and 5 h at 20 degrees C). Similarly, the inward redistribution of these sphingolipids in the plasma membrane of the hepatocyte-like cell line HepG2 and of erythrocytes was slow. However, in rat liver ER and Golgi membranes, we found a rapid transbilayer movement of spin-labeled monohexosylsphingolipids (half-time of approximately 3 min at 20 degrees C), which suggests the existence of a monohexosylsphingolipid flippase. The transbilayer movement of glucosylceramide in the Golgi and the ER displayed a saturable behavior, was inhibited by proteolysis, did not require Mg-ATP, and occurs in both directions. Treatment with DIDS inhibited the flip-flop of glucosylceramide but not that of phosphatidylcholine. These data suggest that the transbilayer movement of monoglucosylceramide in the ER and in the Golgi involves a protein that could be distinct from that previously evidenced for glycerophospholipids in the ER. In vivo, transbilayer diffusion should promote a symmetric distribution of monohexosylsphingolipids which are synthesized in the cytosolic leaflet. This should allow glucosylceramide rapid access to the lumenal leaflet where it is converted to lactosylceramide. No significant transbilayer movement of lactosylceramide occurred in both artificial and natural membranes over 1 h. Thus, lactosylceramide, in turn, is unable to diffuse to the cytosolic leaflet and remains at the lumenal leaflet where it undergoes the subsequent glycosylations. 相似文献
114.
Lysophosphatidic acid is a bioactive mediator in ovarian cancer 总被引:14,自引:0,他引:14
Fang X Schummer M Mao M Yu S Tabassam FH Swaby R Hasegawa Y Tanyi JL LaPushin R Eder A Jaffe R Erickson J Mills GB 《Biochimica et biophysica acta》2002,1582(1-3):257-264
Lysophosphatidic acid (LPA) is a naturally occurring phospholipid that exhibits pleiotrophic biological activities, ranging from rapid morphological changes to long-term cellular effects such as induction of gene expression and stimulation of cell proliferation and survival on a wide spectrum of cell types. LPA binds and activates distinct members of the Edg/LP subfamily of G protein-coupled receptors that link to multiple G proteins including Gi, Gq and G12/13 to elicit cellular responses. LPA plays a critical role as a general growth, survival and pro-angiogenic factor, in the regulation of physiological and pathophysiological processes in vivo and in vitro. Our previous work indicates that abnormalities in LPA metabolism and function in ovarian cancer patients may contribute to the initiation and progression of the disease. Thus, LPA could be a potential target for cancer therapy. This review summarizes evidence that implicates LPA in the pathophysiology of human ovarian cancer and likely other types of human malignancies. 相似文献
115.
Marsche G Hammer A Oskolkova O Kozarsky KF Sattler W Malle E 《The Journal of biological chemistry》2002,277(35):32172-32179
Hypochlorous acid/hypochlorite (HOCl/OCl(-)), a potent oxidant generated in vivo by the myeloperoxidase-H(2)O(2)-chloride system of activated phagocytes, alters the physiological properties of high density lipoprotein (HDL) by generating a proatherogenic lipoprotein particle. On endothelial cells lectin-like oxidized low density lipoprotein receptor 1 (LOX-1) and scavenger receptor class B, type I (SR-BI), act in concert by mediating the holoparticle of and selective cholesteryl ester uptake from HOCl-HDL. We therefore investigated the ligand specificity of HOCl-HDL to SR-BI-overexpressing Chinese hamster ovary cells. Binding of HOCl-HDL was saturable, and the degree of HOCl modification was the determining factor for increased binding affinity to SR-BI. Competition experiments further confirmed that HOCl-HDL binds with increased affinity to the same or overlapping domain(s) of SR-BI as does native HDL. Furthermore, SR-BI-mediated selective HDL-cholesteryl ester association as well as time- and concentration-dependent cholesterol efflux from SR-BI overexpressing Chinese hamster ovary cells were, depending on the degree of HOCl modification of HDL, markedly impaired. The most significant findings of this study were that the presence of very low concentrations of HOCl-HDL severely impaired SR-BI-mediated bidirectional cholesterol flux mediated by native HDL. The colocalization of immunoreactive HOCl-modified epitopes with apolipoprotein A-I along with deposits of lipids in serial sections of human atheroma shown here indicates that the myeloperoxidase-H(2)O(2)-halide system contributes to oxidative damage of HDL in vivo. 相似文献
116.
The availability of safe and reliable, banked tissues in India has enabled the use of human bone allografts as a viable alternative to autografts in reconstructive surgery. Lyophilised, irradiated bone grafts were used in 2 cases of rhinoplasty, a case of hemifacial atrophy, and as a chin implant.In the patient with revision rhinoplasty the rib graft was resorbed. The patient with hemifacial atrophy developed seroma and infection in the zygomatic and infraorbital area and the rib graft had to be removed. The graft from the same rib that was placed over the mandible was retained well and incorporated completely. The iliac crest cortico-cancellous grafts did well in the second case of augmentation rhinoplasty and in the augmentation of chin.The primary objective of reconstructive surgery in the treatment of burns, non-healing wounds and pressure sores is to remove the dead tissue and restore the continuity of the skin without delay. Lyophilised, irradiated, human amnion is a temporary biological dressing conveniently available off-the-shelf. It was used in twenty four patients with burns, eight patients with bedsores and six patients with non-healing ulcers mainly on the foot. The total surface areas of burns sustained were from 2% to 40%. The burns ranged from second degree to deep third degree burns. Amnion was not used in patients with infected third degree burns.The amnion provided good biological cover in all the patients. It was easy to handle and apply, and provided pain relief. The duration of healing varied depending on the extent and depth of the wound and the amount of exudate. The superficial bedsores healed with a single application of amnion. Reduced exudate, healthy granulation tissue and enhanced epithelisation were observed following application of amnion. 相似文献
117.
One of the great strengths of the Framingham Heart Study data, provided for the Genetic Analysis Workshop 13, is the long-term survey of phenotypic data. We used this unique data to create new phenotypes representing the pattern of longitudinal change of the provided phenotypes, especially systolic blood pressure and body weight. We performed a linear regression of body weight and systolic blood pressure on age and took the slopes as new phenotypes for quantitative trait linkage analysis using the SOLAR package. There was no evidence for heritability of systolic blood pressure change. Heritability was estimated as 0.15 for adult life "body weight change", measured as the regression slope, and "body weight gain" (including only individuals with a positive regression slope), and as 0.22 for body weight "change up to 50" (regression slope of weight on age up to an age of 50). With multipoint analysis, two regions on the long arm of chromosome 8 showed the highest LOD scores of 1.6 at 152 cM for "body weight change" and of >1.9 around location 102 cM for "body weight gain" and "change up to 50". The latter two LOD scores almost reach the threshold for suggestive linkage. We conclude that the chromosome 8 region may harbor a gene acting on long-term body weight regulation, thereby contributing to the development of the metabolic syndrome. 相似文献
118.
Bj?rn?Audun?Ris?y Truls?Raastad Jostein?Hallén Knut?T?Lappeg?rd Kjersti?B?verfjord Astrid?Kravdal Else?Marie?Siebke Haakon?B?BenestadEmail author 《BMC physiology》2003,3(1):14
Background
During infections, polymorphonuclear neutrophilic granulocytes (PMN) are mobilized from their bone marrow stores, travel with blood to the affected tissue, and kill invading microbes there. The signal(s) from the inflammatory site to the marrow are unknown, even though a number of humoral factors that can mobilize PMN, are well known. We have employed a standardized, non-infectious human model to elucidate relevant PMN mobilizers. Well-trained athletes performed a 60-min strenuous strength workout of leg muscles. Blood samples were drawn before, during and just after exercise, and then repeatedly during the following day. Cortisol, GH, ACTH, complement factors, high-sensitive CRP (muCRP), IL-6, G-CSF, IL-8 (CXCL8) and MIP-1β (CCL4) were measured in blood samples. PMN chemotaxins in test plasma was assessed with a micropore membrane technique. 相似文献119.
Heterogeneity of microvascular endothelial cells isolated from human term placenta and macrovascular umbilical vein endothelial cells 总被引:6,自引:0,他引:6
Lang I Pabst MA Hiden U Blaschitz A Dohr G Hahn T Desoye G 《European journal of cell biology》2003,82(4):163-173
The present study compares some phenotypic and physiologic characteristics of microvascular and macrovascular endothelial cells from within one human organ. To this end microvascular endothelial cells from human full-term placenta (PLEC) were isolated using a new method and compared with macrovascular human umbilical vein endothelial cells (HUVEC) and an SV40-transformed placental venous endothelial cell line (HPEC-A2). PLEC were isolated by enzymatic perfusion of small placental vessels, purified on a density gradient and cultured subsequently. Histological sections of the enzyme-treated vessels showed a selective removal of the endothelial lining in the perfused placental cotyledons. The endothelial identity of the cells was confirmed by staining with the endothelial markers anti-von Willebrand factor, Ulex europaeus lectin and anti-QBEND10. The cells internalized acetylated low-density lipoprotein and did not show immunoreactivity with markers for macrophages, smooth muscle cells and fibroblasts. The spindle-shaped PLEC grew in swirling patterns similar to that described for venous placental endothelial cells. However, scanning electron microscopic examination clearly showed that PLEC remained elongated at the confluent state, in contrast to the more polygonal phenotype of HPEC-A2 and HUVEC that were studied in parallel. The amount of vasoactive substances (endothelin-1,2, thromboxane, angiotensin II, prostacyclin) released into the culture medium and the proliferative response to cytokines was more similar to human dermal microvessels (MIEC) derived from non-fetal tissue than to HUVEC. Potent mitogens such as vascular endothelial growth factors (VEGF121, VEGF165) and basic fibroblast growth factor (FGF-2) induced proliferation of all endothelial cell types. Placental growth factors PIGF-1 and PIGF-2 effectively stimulated cell proliferation on PLEC (142 +/- 7% and 173 +/- 10%) and MIEC (160 +/- 20% and 143 +/- 28%) in contrast to HUVEC (9 +/- 8% and 15 +/- 20%) and HPEC-A2 (15 +/- 7% and 24 +/- 6%) after 48 h incubation time under serum-free conditions. These data support evidence for (1) the microvascular identity of the isolated PLEC described in this study, and (2) the phenotypic and physiologic heterogeneity of micro- and macrovascular endothelial cells within one human organ. 相似文献
120.